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EF-UK Issue 84 - British Electric Flight Association

1. Inside Front Cover Outside Back Cover Wings amp Wheels Model Spectacular 10 EF UK advertising rates are 25 per inside or outside cover page 20 per full page 10 per half page all per issue Contact the EF UK Editor for more details see page 4 66 E F U K FHNFHRE peu PLANS amp GOODS FOR ELECTRIC POWERED R C MODEL AIRCRAFT Morley Jet Elec Fan WeMoTec Micro Fan 280 300 330 WeMoTec Mini Fan 400 480 WeMoTec Midi Fan 540 600 930 MOTORS MPJet Brushless motors 9 motors outrunners inrunners amp geared 280 to 700 37 00 to 58 00 WEP Turbo 10 Fanfare Silver 16T amp 20T Fanfare Powermax 40T Speed 600 8 4v BB SP Speed 600 8 4v Race HE 380 Rocket 400 Speed 480 BB Pro 480 HS Pro 480 HS BB MAXCIM BRUSHLESS Max Neo 13Y 1430 rpm v Max Neo 13D 2470 rpm v Maxu 35D 21 Cell Controller 35C 25 Cell Controller Superbox 1 6 to 4 2811 50 00 Monsterbox 4 to 6 8 1 Motor Mount 160 00 160 00 140 00 CHARGERS Speed 1 Pulse Pk Det 4 8 cells Speed Ex Digital as above with discharge Simprop 25 cell Wheels Wire Servos Fuses Caps Powerpole 4mm amp 2mm gold conns MAIL ORDER SPORTS ELECTRIC FLIGHT FANS AND GEARBOXES www fanfare f9 co uk GEARBOXES Master Airscrew 25 3 3 5 1 2
2. Even after Jill takes over the Editor s position I wont be disappearing from the scene as I ve offered to read and provide comments on articles to help out I hope to be able to submit articles to Jill on the model building that I want to get on with I do hope to see a considerable number of you at the 3 BEFA fly ins Middle Wallop on 1 amp 2 July Leamington Spa on 67 August and Hayes on 3 September Those at the AGM will also be aware that I ve taken over the Secretary s post As the AGM agreed to the addition of the Welfare Officer post Dave Chinery elected I ve had to re jig the committee list to make more room I ve now grouped the positions held under each person to reduce the previous duplication of names Please continue to send me articles and photographs so that the content of EF UK remains varied and interesting As we near the start of the flying season why not send me a photograph and details of any models you ve built over the winter Regards Jan E F U K 5 New 2 U A Brief Round up of New Items of Interest If you are a manufacturer or retailer that has something new they want to share with the readers please send details to the Editor addresses on page 4 First up is a range of interesting new brushless outrunner motor incorporating a built in spinner from Robotbirds They each have a rear mounting flange which can be removed if desired There are 3 different sizes The 380 which is 1770 rpm v a
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4. I decided to get back into aeromodelling after a 20 year break due to the impending birth of our first child it was either now or wait several more years With this in mind I needed a model that was going to be quick to build reasonably priced and perform the task of trainer and performance flyer further down the line I guessed I wasn t going to have much time to build anything else After various discussions with fellow flyers I decided to try an electric glider as this would fly nice and slow during the learning phase and if chosen carefully should be a good performer in thermals once I was proficient enough to find them I chose the almost ready to fly Filip 600 made by RCM Pelikan and supplied by Puffin models My choice was based on recommendations from experienced flyers along with good reviews and write ups found on various web sites certainly recommend the web as an excellent source to research your intended purchase Puffin models also recommended a motor Permax 600 7 2V speed controller Rondo 600 pro and propeller Graupner folding 9 4 combination for the drive train and I purchased these with the model Building The kit arrived well packaged without any damage The wings are ready built along with the rudder and tailplane elevator assembly leaving the fuselage to be assembled to suit the radio gear etc to be fitted The build is straight forward and quite well detailed in the accompanying instructions I won
5. Beginning at the front of lobe 1 neatly wind on 13 turns of wire starting from the front Having completed the number of winds pass the wire then around the front of lobe 2 through the slot between 2 and 3 behind lobes 3 and 4 returning it through the slot between 4 and 5 Complete the winding of lobe 4 From the final wind on lobe 4 pass the wire in front of lobe 5 through the slot between 5 and 6 behind lobes 6 and 7 returning 1t through the gap between lobes 7 and 8 Complete the winding of lobe 7 The first phase is now wound Take a second length of wire and proceed with winding phase 2 Start by loosely twisting the start of this wire to the end wire at lobe 7 then wind lobes 8 2 and 5 in that order following the same plan as for phase 1 This is phase 2 successfully wound Now take the third length of wire for phase 3 and loosely twist 1t 1nto the end of phase 2 lobe 5 Wind lobes 6 9 and 3 The end wire of this phase will be connected to the start wire of phase 1 10 Almost Done The 3 pairs of wire ends have had the insulation scraped off and twisted together These have been fitted through the holes in the solder plate With the drill blank fitted slide the bearing tube over it and carefully fit the wound stator and solder connection plate over this Careful when it gets near the magnets they will grab it With the bearing tube fully into the motor can and the stator sitting 1n its magnetically ba
6. E F U K 55 really only designing for myself and subsequently the drawings 4 hers I made were good enough for me to build from but not really clear enough for anyone else to follow A few club mates have expressed interest in the models and they have then received better drawings with more detail and an attempted list of instructions but until now that 18 as far as the drawings have gone I was flying at the Walsall meet last August when I was approached by Mike Windo who expressed a desire for a set of drawings of the Mark 1 Sprite We got talking and I agreed to send him a set of drawings of the Mark II from which he could build from Having made the commitment the problem was then completing my drawings to a standard that another modeller could follow Mike living in Cheltenham and me in Milton Keynes meant that he could not just pop in to see how certain bits fitted or be able to see the model at the strip he would need to understand the drawings if he was to make a successful model It also transpired that Mike was a retired Drawing Engineer so knew a thing about plans and so forth I was self taught on AutoCAD I always did enjoy a challenge I am pleased to say that after a period of time the drawings were completed along with photographs of the construction and a detailed suggested build sequence for the model and although it took me longer than I expected not entirely helped by my day job situation I really did enjo
7. WANTED Member s Sales amp Wants The items below for sale by Trevor Wain contact at trevorwain tiscali co uk or on 01332 792 508 Puffin Models Elegant 2 6m glider electric glider Flown twice but other interests took over no equipment fitted Offers around 100 e Kontronik Smile 40 6 18 opto brushless speed controller 40A 6 24V with Kontronik 4mm silver connectors on the output and Schulze 3 5mm connectors on the input and has been used twice He would like to exchange for the same or very similar with BEC or sell for 65 Neil Stainton is selline the following items All are plus postage or can be picked up from Leamington Spa Contact Neil Stainton on 01926 314 011 or email him at Neil ITpartnership com e New Blade Runner indoor helicopter including 27Mhz R C LiPo battery amp charger 35 Hornet Helicopter FP VGC with carbon blades 20 Jim Horne has the following items for sale email Jim at HORNEGb aol com or phone 01388 819 638 WeMoTec Midi fan with 36 24 2 sensorless brushless motor 70 FVK RIVAL 2 8m span fitted with a Kontronik 480 brushless with 5 1 gearbox Hacker 70A ESC six new servos Schulze 8 channel receiver Carbon propeller amp spinner and comes with a 3300mAh flight battery 450 00 or vno or swap what have you got Neil Stainton wants a Highlight Electric Fuselage any condition Contact Neil at Neil ITpartnership com or on 01926 314 011
8. spending 20 on various fluxes I still could not solder onto the high alloy drill 48 E F U K blank I resorted to using brass collet soldered square to the front of the bush and the prop shaft would be held in place later with the grub screw 4 Cut to Size In the above photograph the collet can be seen soldered to the front bush I ground a small flat into the drill blank for the grub screw to locate against The new neodymium magnets will locate against the small dimples which are pressed into the can which can be seen close to the front face From the rear edge of these dimples measure back about 11 to 12mm This is the cut mark for reducing the can to size Using a bench mounted drill clamp the prop shaft of the motor in the chuck With the drill running use a junior hacksaw to slowly cut through the casing This gives a nice controlled and even cut It s best not to cut right through using the power drill but remove the motor casing from the chuck and finish the cut with the casing sitting in the jaws of a vice The results are quite good after the ragged edges have been smoothed off 5 Throw Away Some More Bits E F U K 49 Here the can is shown cut into 2 parts The rear portion and brush holder can now be discarded 6 Sort out the Sticky Magnets The neodymium magnets have to be arranged with their poles aligned N S N S etc and assembled into the motor can in that order Use a piece of steel to l
9. BEFA ElectroSlot and E400 League event at Pillerton Hersey OS Grid SP 4922 4918 For more information contact David Perrett 01455 272 297 or by email at d L perrett btinternet com October 2006 15th BMFA NW Area Indoor Fly in see 16th April for details November 2006 5th BEFA Technical Workshop amp Traders Fair Leamington Spa 19th BMFA NW Area Indoor Fly in see 16th April for details December 2006 17th BMFA NW Area Indoor Fly in see 16th April for details January 2007 21st NW Area Indoor Fly in see 16th April 2006 for details February 2007 18th BMFA NW Area Indoor Fly in see 16th April 2006 for details March 2007 Ath BEFA 2007 Annual General Meeting at Leamington Spa Warks 18th BMFA NW Area Indoor Fly in see 16th April 2006 for details E F U K 61 Southern Area Electric Fly In June 18th 10am 5pm Access off the A272 Winchester to Petersfield road Trophies for scale aircraft by popular vote and other trophies for outstanding models Barbecue Lovely site courtesy of Winchester MAC with large area of short mown grass Join us for a relaxing fly Non BMFA A certificate holders will need to be a qualified pilot we can assign one eigh All frequencies will be used Entry fee 3 per pilot For more information contact Andy Palmer at 92 Durley Ave Waterlooville Hants POS 817 Tel 023 92 253761 Email palmer99 tiscali co uk 62 E F U K f IFOR SALE
10. NiMH cells It looks a bit agricultural at first glance but it is actually quite nicely made with good quality machining and powerful probably Neodymium magnets The only place it would lose out to say AXI is that it appears to have plain bearings rather than ballraces I haven t figured out how to get 1t apart so I can t be sure Then again Speed 400s have plain bearings and no one seems to worry too much about it It weighs a bit less than 20z 56g as you see it around oz 21g less than a Speed 400 The mounting bracket has a 3 81n square hole the same size as GWS stick mount motors and the shaft is 3mm to fit GWS propellers Spotted the target market yet gt The speed controller I got is labelled HM 15A dunno what the HM stands for but the 15A is self explanatory I notice that some of the twenty quid combinations come with only a 10A speed controller so maybe I didn t do so badly after all Once again it looks very nicely made The two thin wires coming out of the motor end of the controller go to a two pin plug fitted with a jumper that sets the low voltage cutoff LVC for the motor jumper on for 25 Lithium jumper off for 85 E F U K 19 It has the usual whizzo features we take for granted these days like automatic adjustment to match the throttle stick throw and not starting if your throttle is wide open when you plug the battery in If someone had told me about these when I
11. another but make a few modifications that I felt would improve the performance and the general convenience of the model The major change being the construction of plug in wings using 4 diameter Carbon Fibre rods 1n Aluminium tubes as opposed to the single wing bolted in to the fuselage 1n the usual style model as presented represents those changes and has more than achieved the design criteria set out in the beginning The current set up is now running on 2820 12 with 3S Hyperion 3700 mAh LiPo and they have taken another ounce off the AUW I am running a Master Wooden 11 x 7 propeller which I like very much but am thinking of experimenting with some of the electric propellers to get some better vertical performance I am only running at 286W on the ground so have some way to go with the motor before I get any problems so there is a vast scope to improve the vertical It will The Sprite on the ground resting E F U K 5 hold the vertical at the moment on full power for some time before falling off but I think the limiting factor is me and not the aeroplane Having gone this far I can now offer plans and a construction guide for 10 including UK postage amp packing to anyone who is interested in the model For more details contact John Bowerman at johnbowerman f2s com Editor I was so impressed with the Sprite already got my of the plan just need time to build it If you don t have i
12. fuselage before gluing the servo plate in place The whole build took me about four weeks I guess a competent builder with time on there hands would at least halve this Now I just had to wait for a good Wednesday afternoon for the maiden flight E X Here s the happy pilot Ewan in traditional pose with his Filip 600 Flying The wait was a lot longer than expected due to the appalling summer we had this year and in the end the maiden flight was in far from perfect conditions The wind was blowing at about 16 mph and was showing no signs of easing when my fellow flyer instructor Rob decided it was time to give it a go The Filip was given a good heave and climbed away on full power as steady as rock straight into the breeze Rob was very impressed with its performance and I had 12 E F U K Inside the nose showing the back of the motor speed controller is soldered directly to the terminals good choice of Power Pole connectors and Hitec HS81 servos a quick 10 minute flight with it myself just pointing it into the wind and slipping it left and right on the rudder Getting the Filip back to earth proved the hardest task and it took several approaches before Rob managed to get it on the ground It finally came to rest upside down but survived without any damage to fly another day Further flights have been limited this year by the weather and the need to decorate a nursery but I have been able to build up my experienc
13. motor construction will be even cheaper as I have some material left over and quicker to build Because the motor is a Speed 400 diameter and also because the wires exit the motor in a position where they cannot be rubbed by the rotating can it is ideal for the dozens of planes drawn up for Speed 400 s The Typhoon range for instance has similar performance characteristics but the diameter is much greater and the wires exit near the front mounting plate and usually have to be routed past the rotating can This increases the mounting diameter to an even greater extent 54 E F U K The Sprite by John Bowerman I have been designing my own models for about 8 years now ever since I went fully electric It started as a challenge because like many I guess what I wanted could not be bought commercially so in order to satisfy myself the only way was to design and build I have had few that could be best described as not that good but in truth not many and all have flown to a greater or lesser degree I started by drawing on to paper with large rulers set squares and compasses but eventually I was able to get hold a decent CAD package and then more importantly a decent sized plotter courtesy of E Bay These two factors have enabled me to really focus on both the aesthetics of the design and also the accuracy of all the fitted parts and have led to a continued stream of successful flying models An excellent shot of the Sprite
14. saw this unique biplane twin pusher model at the BMFA NW Area indoor meeting at Rochdale David Lloyd Jones had one and was passing the TX around for seemingly ages He had bought his from Maplin Electronics so a visit was made to the Leeds branch There was a pile of these models reduced in price from 29 95 to 19 95 FENY This includes the excellent TX which doubles as charger al MN for the Lithium battery built 7 into the model and all that is needed are six AA batteries Steering is by differential throttle on the Contra Rotating motors and so the Mode 2 TX has throttle on the left and steering on the right Wings and fuselage pod are a foam moulding with a tubular plastic boom and Depron tail feathers Four different spots on 27 MHz are available 1dentified by the colour schemes Wingspan is just under 9 220mm and weight 20g Charging is simple just plug the pigtail from under the transparent screen on the TX in the socket under the model and wait for the LED to go out The turning circle is not tight you would not fly this in your average living room which is probably why they were reduced in price but in a Gym there is plenty of space for figure 8s I have flown mine at full length of a 5 Badminton court hall without range problems and flown two on adjacent spots Passing shock flyers cause interesting gyrations due to turbulence but nothing 16 E F U K else The flight trim 15 near the
15. second batch I would be happy to try to answer technical questions anyone may have and can be contacted by email at marywayne giles150 freeserve co uk E F U K 45 Do It Yourself Brushless Motor by Rob Ireland All the parts which didn t break in the crash were too heavy This is my version of a DIY brushless 400 size motor from the article written by John Rutter in Q amp EFI Jan 2005 Why bother It s a good question The outrunner type of motor magnets revolving in the outer casing around a stationary core of windings is very simple to make and as a result there is now a vast choice of these brushless motors available There are dozens of manufacturers advertising this type of motor at reasonable prices There is a 10A motor including speed controller available for less than 20 There are probably 2 reasons to DIY One is the same as all other DIY subjects the strange pleasure which comes from fiddling with things we are not good at triumphing in the face of adversity The other is the ability to tune the motor to the application This can be done by altering the number of winds on the core fewer winds hotter motor more winds slower motor and bigger prop On this type of motor construction it can also be achieved by the length of the stator core laminations My motor I wanted to replace standard Speed 400 motors which are limited to about 10A and only 5596 efficient with a brushless mot
16. t go into the fine detail but it was within the talents of someone who hadn t picked up an exacto knife in over 20 years I was severely tempted to try to reinforce the wing and tail fixings but at the advice of a fellow flyer I decided to stick resolutely to the instructions I think I would have ended up adding too much weight which would only result in greater momentum during any impact The only modification I did make was to the battery mounting plate I added a small 1 8 balsa bulkhead on which the battery mounting rested instead of the small piece of spruce strip intended for the job I also added a small piano wire hook at the back of the battery mounting plate and a dowel peg at the front so that I could hold the battery pack in place with a sturdy rubber band The only other departure from the instructions was the canopy fixing I couldn t understand how the fixings supplied with the kit were supposed to work so I just use tape instead E F U K 11 There is a range quoted in the instructions for the position of the CG measured from the leading edge I positioned the battery pack and other components inside the fuselage so that I had the required adjustment over the CG by moving the battery alone I didn t want to add any lead to get the CG right later on The Hitec HS81 servos I used fit very neatly into the fuselage allowing plenty of space to move them around to align them perfectly with the control pushrods running up the
17. the design of loads which have an A C element in them I had investigated the possibility of measuring ESR last year and had gone as far as building a rig which operated on a pulsed principle and produced a DC output voltage equal to the difference between off load and on load voltages at a set current The ESR could then be calculated from these figures This was before my experience with the Protech Ultimate and the three 700mAh LiPo batteries It was this latter experience which set me to thinking that there must be a way of building an instrument which would produce the results we want to know directly Although the actual value of the ESR is academically interesting to us anoraks what the user wants to know 1s how efficient a particular setup is and how much power goes to the motor with a particular battery I had some wild idea about applying a linear current ramp load to the battery under test and reading the current level at which the battery voltage had fallen to E F U K 39 say 80 of its no load voltage This would then read out the current at which the battery would achieve an efficiency of 80 I was corresponding with Bob Smith about the problem at the time and he asked the question Why not turn it round start with the current for a particular fixed power train and make the instrument read out the efficiency This was obviously a much better way to proceed and it overcame a scaling problem caused by the square la
18. times its charge rate 100 or greater Less than this and you end up with either a battery too big and heavy for the model or a battery about the right size and weight but not enough power at full throttle for a good climb out Recent LiPo battery developments have broken this 10C barrier For brushless motors I am not sure what the rule of thumb figures are I have made some discoveries by experimenting with a couple of small brushless motors one geared and one direct drive outrunner I discovered that itis possible to get very good power to weight from a 2 cell 7 4 volt LiPo using a battery size matched to a motor where the current draw 1s equal to 10C at full throttle I have also found that with this power to weight ratio throttling back for cruise gets me the 10 minute flight There should be another figure concerning power to weight ratio to give a good safe rate of climb but I do not have a simple one here Editor You could use the rule of 50 or 100 That is 5077 16 for sport models and 100W Ib for aerobatic models This is a fairly crude system but this general rule works well for most models Having said this 1s our hobby all about calculating numbers Of course not it 1s about enjoying the look and feel of a good model in flight how it climbs how it sits in the air and exploring its virtues and vices 32 E F U K I will share with you some examples of how some models of mine have been transformed by
19. to be the most stressful aircraft to fly that I can remember but that 1s irrelevant to the present story I was using 700 Neodym which I had bought years ago and never used modelling syndrome and was determined not to waste Suitably over propped it drew 40A from a 15V supply so that I was looking for a suitable battery and considered 12 x Sanyo RC 3000HV cells or 493P Konions I tried the Sanyos first as they were the cheaper but the weight penalty later decided me to change to the Konions based on encouraging figures I had measured last year I took a set of figures from each pack and have extracted the figures at 40A to show the information they give The tests were carried out at 25 C which is important more of that later E F U K 41 Displayed Results Current Efficiency Motor Battery Loss Amps W W 12 x Sanyo 3000 40 83 3 537 108 4S3P x Konions 40 84 6 564 104 These are the figures read directly from the unit but other useful information can be derived from them ESR of the pack plus connectors is given by dividing the battery losses by the square ofthe current The on load voltage 18 given by dividing the load power by the current The off load voltage 1s given by dividing the on load voltage by the efficiency Calculated Results ESR OnLoad Load Power Weight mQ Volts Volts Watts Kg 12 x Sanyo 3000 67 5 13 42 16 13 706 x Konions 65 0 14 10 16 67 1029 The weights of the two packs we
20. to Electric Fight Start Here 65 Pillerton Hersey 2006 22 Dales iive te vt bertus 66 A Staggerwing Conversion 30 Advertisers Index 66 Cover Photo The cover photo is John Bowerman s Sprite aerobatic model It has a wing span of 52 132 cm and 1s designed for motor such as the AX1 2820 10 or 12 with 85 LiPo around 3700 mAh More details of the model including how to get the plan start on page 55 NEXT ISSUE The copy date for the Summer 2006 issue is 31 May 2006 with the magazine due for publication by 30 June 2006 DISCLAIMER B E F A and Electric Flight U K wish to point out that the content techniques and opinions expressed in this magazine are those of the individual authors and do not necessarily represent the views of either the Editor of this magazine or and its committee O All information in this magazine 1s copyright of the authors Any request to use information from this magazine is to be made to the editor contact details overleaf All reasonable care is taken in the preparation and compilation of the magazine but B E F A and its committee cannot be held liable for any error or omission in the content of this magazine or any subsequent damage or loss arising howsoever caused To allow proper appreciation of the photographs used colour copies of them will be posted on the B E F A website afte
21. wooden wheel axles The model came with a geared 280 brushed motor Flying with this and the 2 cell 640mAh 15C Kokam LiPo battery produced very marginal climb rate In went a 8 cell LiPo This was much better for about five minutes till the motor burnt out Since then I have bought a 280 geared brushless motor and HM 15A speed controller from RCM Direct This gives great climb performance with the 2 cell 640mAh LiPo 15C battery so I am in business with a practical flying machine How does it look and feel in flight Well the first thing I noticed was the difference turning left and right I imagine this is a bit like the real thing where the combination of a short stubby aircraft and large propeller gives a gyro effect Turns to the left model 1s rudder elevator controlled are docile and the model naturally climbs Turns to the right are very snappy the model whipping round to face in the opposite direction very handy when the Red Baron is on your tail Ground handling is surprisingly not bad The model can be flown in and out of a cricket pitch with little tendency for the tail to swing Cruising at half throttle between manoeuvres allows a 10 minute flight time The Pico Fli I have developed what I call a Pico Flu This is a Pico Stick with built up wings and ailerons in the style of a Fun Fl model Until recently this had the original geared brushed 150 motor The model in this form was reluctant to perform m
22. 18 00 Planetary 3 33 amp 3 8 1 400 Pro 480 28 00 MP Jet Planetary 3 33 8 3 8 1 Speed 480 28 00 MP Jet Planetary 3 33 amp 3 8 1 540 600 MP Jet Plastic BB 4 amp 5 1 280 300 MP Jet Plastic BB 3 3 5 amp 4 1 400 Pro 480 8 00 MP Jet Plastic BB 2 33 3 5 amp 4 1 Speed 480 10 00 MP Jet Plastic BB 1 75 2 33 amp 2 8 1 540 600 15 00 Mini Olympus Olympus Speed 400 FG3 SpeedGear 400 4 1 Inline SpeedGear 480 3 4511 55 00 SpeedGear 600 2 8 1 SpeedGear 700 2 7 1 9 6v SpeedGear 700 Neo Mini Olympus amp RE380 Olympus amp 540 Jamara 600 2 9 1 24 00 Jamara 650 2 9 1 26 00 M A Wood Electric 10x6 10x8 11x7 11x9 12x8 12x10 13x8 13x10 Carbon Folders Perkins 8x4 8x6 9x6 3 50 512 12 dia 23 to 4 13 20 dia 5 to 15 Slimprops APC Electric full range available Selection of Graupner amp Aeronaut folding amp fixed props FANFARE 18 HILLSIDE ROAD TANKERTON eWHITSTABLE KENT CT5 Sports Electric Helpline Phone Fax 01227 771331 E mail john swain1 virgin net Now online at www fanfare f9 co uk VERGA cG DAITE eae VISA mmn FEES Ferr 2 tional ai 1 F me PME Lat PLAN AN e z Scale Modeler
23. EFA event NO TEST FLIGHTS ON THE DAY Standing Events 1st Sunday of every month The Brighouse Vintage MAC have been using the small airfield at Tockwith near Wetherby Yorkshire for several years but have recently had noise problems The field 1s now all electric and any BMFA Member 58 E F U K is invited to fly there on the First Sunday in each month from 10 to 5pm for a small fee Do not be put off by the Vintage part they fly anything There is a concrete runway available and details of the site can be obtained from Derek Haviour on 01422 204 472 April 2006 8th 16th 16th May 2006 14th 21st 26th 27th June 2006 Ath 11th 11th North London MFC Indoor R C Meeting See 14th January BEFA ElectroSlot and E400 League event at Pillerton Hersey OS Grid SP 4922 4918 For more information contact David Perrett 01455 272 297 or by email at d L perrett btinternet com BMFA NW Area Indoor Fly in at the Springfield Sports Centre Rochdale Flying from 11am to 5pm 3 per person card must be shown For more information see www bmfa nw org or email KeithAtRochdale aol com The Tom Taylor Memorial All Electric Fly In at Phoenix MFC The Old rifle range off the 12 Pakefield Lowestoft The Tom Taylor memorial shield will be presented again to the best model amp flight combination of the day A certificate minimum to fly solo amp proof of BMFA insurance required Book in from 9 30 flying
24. ELECTRIC FLIGHT ux ISSUE No 84 SPRING 2006 4 THE MAGAZINE OF THE BRITISH ELECTRIC FLIGHT ASSOCIATION THE HOME OF Welcome to The E Zone The virtual home of electric flight M G A Z I FHEE Discussion forums Areas for all types of glider electric fuel planes plus car and boat modelers Galleries of hobby photos from modelers all over the world E Flight mailing list thousands of members world wide Classified ads Three Separate In depth Webzines Ezonemag com rcpowermag com liftzone com Regular columns and HOT NEW PRODUCT reviews 1 all areas of RC YEARS of articles archived www rcgroups com Electric Flight U K issue 84 Spring 2006 Encourage and Further all Aspects of Electric Model Flight in the British Isles and Elsewhere B E F A Constitution CONTENTS Committee 2005 6 4 Learning to Love LIPO S 92 Chairman s Chatter 5 Road Tsting Batteries 37 ER 5 Do It Yourself Brushless Motor 46 NOW test baee Pot 6 The DDEIU ci iced 55 First Steps in RC Electric Flight 11 Event Calendar 58 Cheap Indoor RC eee 16 For Sale Wanted 63 TLC from your TLO eene 18 New
25. Kg reel available from RS Components part no 357 738 If you don t want to experiment with windings smaller packs are available from C amp K Designs How to do it 1 Take Apart a Speed 400 File prise or grind off the lugs at the brush holder end of the motor can The brush holder can now be pulled free with the armature following next Remove the spring clip which retains the 2 magnets The clip magnets and armature can be discarded E F U K 47 Carefully close the magnet retention wings nice and flush with the can protrusion of these on the inside of the can will affect the seating of the new magnets 2 Drill out the Brass Bush This needs to be done carefully as this operation will dictate how co axial the outrunning magnets will be to the propeller shaft I used a 3 2mm drill in a hand brace Using the chuck the drill can be cut into the brass bushes quite easily Drill the rear bush in the brush holder first then temporarily reassemble the brush holder to the empty can Feed the drill in through the enlarged brush holder bush and carefully open out the front bush For some reason I have photographed this drilling operation back to front 3 Test Fit the Prop Shaft This shows the 0 125 drill blank temporarily fitted through the empty motor casing At this stage the drill blank was to be soldered to the front bush leaving about 10mm protruding onto which a standard prop adaptor would fit After
26. Peter Vivian would like to contact any others in his approximate area Camberley Surrey who are also new to Electric Flying with a view to mutual assistance and support Peter returned to model aircraft fairly recently after a 55 year break with an interest mainly in building and experimenting definitely NOT ARTF He would like to meet up with others having similar interests Contact Peter by email at PGLV aol com or on 01276 21 304 E F U K 63 Wanted by the Editor any of the following see page 4 for contact details 64 e General Technical Articles Hints amp Tips New Product notifications Product Reviews Photographs of your models Electric Flight Event Reports Any other item of interest to electric model aircraft flyers Please send colour Digital photos or photographic prints 6 x 4 or bigger to the editor If possible please do not send inkjet prints as too much quality 1s lost during the printing and scanning process If you have no way to email or write the files to a CD please contact the Editor for other options Photographic prints supplied will be returned unless specified otherwise as long as you give a return address Digital photos should be sent at the highest resolution possible in colour and preferably uncompressed Where compression is unavoidable the camera should ideally be set to the lowest compression possible and at the maximum resolution Digital ph
27. The power 1n Watts lost 1n the battery 1s equal to the voltage drop across the ESR multiplied by the current As the voltage drop 1s equal to the ESR multiplied by the current Ohms Law V IR then it follows as Power Voltage x Current that the power lost in the ESR 1s equal to ESR x Current x Current That is Power Lost I x ESR The real problem here is that the power wasted in heating the battery pack 1s a function of the square of the current Double the current and you are throwing away 4 x the power as heat in the battery All these laws of physics are beyond our control despite what the public relations men would have us to believe but we could have some control over the ESR value if only we knew which batteries had the lowest ESR Either by accident or design the manufacturers choose not to inform us If challenged no doubt they would say that the average user does not understand it or that it is not as simple as that The latter is true in a literal sense as battery impedance is made up of some pure resistance some more resistance with capacitance in parallel amp some small inductance The inductance is of no consequence to us and the parallel C R combination is only a minor part of our problem so that as far as the modeller is concerned it is the pure resistance which is the villain To be fair manufacturers have always quoted an impedance figure usually at 1 kHz which I have always assumed is to help with
28. anoeuvres Mainly I think this is due to a combination of the power to weight ratio and the large geared propeller having a braking effect almost immediately when you dive to pick up speed This model was definitely heading for the bring and buy sale I bought a small brushless outrunner bell motor and speed controller from All Electric RC at the BEFA Technical Workshop This I fitted with an 8 x 4 propeller and powered by a 640mAh 15C Kokam LiPo battery This has transformed the model which will now do stunts including consecutive climbing loops Again a 10 minute flight time is achieved by throttling well back between manoeuvres What Next I feel confident now to proceed with other scale higher wing loading Park Fly subjects such as the GWS World War II fighters I fancy a P 51 Mustang witha bell outrunner motor and 640mAh LiPo So I have learned to love LiPo s All motor battery and speed controller purchases met or very nearly met my rule of 20 per item stated at the beginning All of these combinations also achieve my rule of 10 minute flying time and now have good power to weight LiPo s have their well known foibles such as sensitivity to over or under charging and the tendency to go out of balance Editor Under charging is not a problem as it does no harm to the battery just to flying time However over discharging certainly is a problem and must be avoided at all costs Th
29. ay out the magnets side by side If the poles are opposing they will not sit as shown in the photograph When all 12 are arranged as shown mark them suitably 7 Assemble the Magnets into the Motor During the assembly of the motor I was able to ensure the prop shaft and stator would be accurately concentric with the revolving magnet casing The mounting of the shaft using the collet and grub screw now allowed the shaft to be withdrawn thus making the magnet placement much easier than otherwise To space out my magnets evenly I had to experiment with spacers which took a little time to do A strip of 1 32 ply was used onto which I stuck 2 or 3 layers of masking tape The resulting composite was cut into slivers which were placed one between each magnet not shown It is virtually impossible to place the magnets without spacers When all the magnets are in position the spacers can be very carefully removed relying on the balanced magnetic flux to keep all in position Initial fixing of the magnets can be done with some thin cyano This was followed by a mix of epoxy with the whole lot kept warm enough to let the epoxy flow nicely 50 E F U K If the magnets too hot to touch they will lose their strength Final cleaning up of the epoxy was done before it had fully set using methylated spirit 8 The Stator Shown above are the 2 stators each about 5mm thick They have been cyno d together with the lobes lined up an
30. battery heat clearly shows the square law take 30A and you throw away 40W in battery losses take 60A and the losses rocket up to 161W well over one third of the power going to the motor Also note that the first 10A of current delivers 97W of power to the motor wasting only 4W in the battery whereas the last 10A of current adds a mere 36W of motor power yet throws 66W away in battery heat I should point out that the cells in question are only intended for use at 40A or so but the figures demonstrate that taking excessive currents from a battery give little return In the case of Lithium batteries it also rapidly shortens their life I have used the unit to differentiate between Lithium packs with genuine 15C and 20C ratings from the pretenders The latter types stick out like a sore thumb The other variable we need to be aware of is temperature All batteries have a negative temperature coefficient of ESR so that they all work better at higher temperatures within limits However we need to be aware of how it affects results when comparing two battery packs particularly if comparing cells of different chemistry It appears that Lithium cells have the highest coefficient NiMH next and NiCd the lowest It follows therefore that Lithium are at the biggest disadvantage at low temperatures but what we are interested 1 1s how they compare under practical conditions I therefore try to ensure that packs are left to settle to the sa
31. d the bores concentric with the mounting tube In this case the mounting tube is a piece of aluminium alloy which will take a bearing race in each end of it About 35mm long 1s adequate for its purpose Carbon fibre tube 18 equally useful for this and 1s available with an outer diameter of 8mm which 1s an accurate match to the bore of the stator Fit the ball races into each end of the tube using the drill blank again to ensure that everything 1s running true Apply a small amount of cyano or epoxy to the outer race if necessary and allow to set 9 Winding the Stator Start by numbering each lobe of the stator with an indelible pen I will also consider this numbered face as the front and the opposite side will be the rear There are 3 separate pieces of wire which have to be wound onto the stator to produce the 3 phases Each wire will need to be wound round 3 lobes I had decided to build this motor with 13 winds in a delta connection the end wire of each phase 1s connected to the start wire of the next phase ot PHASE START T g d MASE START Ist PHASE END Zad PHASE 2 E F U K 51 The first phase is wound starting with stator lobe 1 and will progress onto lobe 4 then lobe 7 It is important to make all the winds in the same direction and to wind the same number of coils onto each lobe this is surprisingly difficult to do The stator can be held in one hand while winding which helps
32. d widely known within the industry I have never done any competition flying but assume that it would be useful for the competition flyer to be able to instantly find his best battery pack 44 E F U K Validity of Results Although the instrument allows us to measure high power performance of our batteries literally at the touch of a button the reader may wonder of the validity of the results I have calibrated the unit very carefully and tried to check results where possible The basic efficiency measurement which I originally set out to do simply expresses the on load voltage as a percentage of the off load voltage As the current is common to the battery and the motor then this percentage figure applies to the power also Avery encouraging fact is that the two power figures which are derived via a very different route from the efficiency always give the same result as the direct reading within about 0 5 Repeatability of results also suggests that the measurement system 18 valid I would add a word of caution in calculating ESR values As we use the Battery Losses power figure to calculate ESR it 1s wise to take the measurement at the highest practical current This 1s necessary because the reading 1s derived from a small difference between two large voltages which will magnify any errors Also any digital readout must or 1 count so that any reading of 9 or less cannot be better than 10 accurate The table o
33. e to the point where I can land the model myself in still conditions and fly circuits without too much help from my fellow flyers I can t stress enough how important it has been to have experienced flyers with me to take over when I ve got into difficulty The Filip would certainly not have survived the summer without them Asa trainer the Filip has been ideal The relatively slow speed of the model gives you plenty of time to correct mistakes and by flying with plenty of height stalls can be recovered easily The performance of the Filip 600 on a 7 cell 2200mAh NiCd pack is excellent I regularly get flights of 25 minutes On one occasion I managed to find thermals to circle in and the Filip climbed to the point where I was worried I d loose sight of 1t E F U K 13 Ready to launch Fly by 14 E F U K Fly Over this amazed me bearing in mind the model is carrying a 7 cell NiCd pack and 600 size motor sum up I would say I am very pleased with my choice of model to get back into the hobby The Filip 600 has proved a good trainer and has the promise of a good thermal soarer when I get more proficient at finding lift Numbers Radio gear Hitec HFS 04MI Receiver 2 off Hitec HS81 servos Measurements Fuselage length 115 cm Wing span 200 cm Wing Area 38 2 dm Weight all up 1300g RCM Pelikan s target is 1250 1300g E F U K 15 Cheap Indoor RC by John Thompson TANA We first
34. ese have not affected me yet in the six months I have owned my LiPo packs For me provided they last for 50 or so charge cycles another number rule I will be more than happy Any questions or comments I will be pleased to hear from you at sandra brianrawnsley freeserve co uk Road Testing Batteries by Wayne Giles I was intending to title this article Quantifying Battery Performance but changed to the present title because people tend to shy off from technical articles with formal titles As I have changed the formal title bit meet me half way and put up with the technical bit I will try to minimise it but if you fly electrically powered models then you must have something of a technical bent especially if you are interested enough to join the BEFA Background a life long modeller and a retired electronic engineer but only started flying electrically powered models about three years ago The reason for this is that up until brushless motors appeared I had the view that the average electrical model usually staggered round on the verge of a stall or else it was a flying house brick because the owner had put in enough NiCds to try to produce real performance I always felt slightly guilty about this having spent my working life in power electronics but with the latest advances in outrunners and Lithium batteries I am now aconvert and thoroughly convinced that electrically powered models can compete on a level playin
35. f 10A 80A results demonstrate this if you calculate the ESR at each current you will see that the first two readings are 1096 low and 6 low respectively whereas the results 30A upwards are consistent within 1 Asthe unit can measure losses from which we can calculate the ESR as described above then 1t 1s possible to measure the resistance of other connectors and or leads To prove this I took a nominal 22 milliohm resistor accurately measured its value with a high current and accurate instruments I then soldered it in series with a battery on test I calculated the ESR from the losses with the resistor in circuit and the ESR without it The difference in the two values was equal to the known value of the resistor within 0 4 I would not claim an accuracy of this level but it suggests that a claim of 2 would be reasonable As the efficiency is quoted as a percentage the voltage of the battery under test does not affect the result so that it is possible to compare a 3 cell Lithium battery with say a 14 cell battery the efficiency figures are directly comparable Only the power readings are affected by the different voltage and these can be quoted on a watts cell basis so that the performance of a battery made up of any number of cells can be forecast Since building the prototype three people have asked me to build one for them so I am in the process of making a batch of six units If there 1s enough interest I may consider a
36. figures It was therefore decided to use a single shot principle and store the results The three results are displayed on a 3 digit LCD display 3 way switch choosing the displayed parameter The current is preset in 10 steps by a 10 way rotary switch up to a maximum of 100A with a toggle switch adding 5A to give a range of O 100A in 5A increments In terms of voltage the unit will cope with 5 18 NiCd NiMH cells or 2 6 Lithium cells maximum power capacity being 2000W To operate the unit the battery 18 connected to it via two 4mm front panel sockets and the current switch set to the required value Pushing the Operate button will produce a reading 1n about one second 40 E F U K The display is automatically stored and held until the next reading is taken Any of the three parameters discussed can be displayed but it must be selected before taking a reading Operation is so quick and easy that it was possible to take all the results in the table shown ranging from 10A 80A in about 5 minutes The unit requires about 170mA at 12V de which is normally supplied by a plug type PSU but it will happily operate off any 10 16V DC supply Results and how to use them The best way to demonstrate the use of the unit 1s to look at the results taken from two comparable batteries and see how helpful conclusions can be reached I was looking to power a Graupner ASH 26 for some relaxed flying It turned out
37. first started this electric flight caper I would have laughed in their face progress truly has been remarkable Brake is enabled by default you can disable it by putting the throttle stick to max plugging in the drive battery listen for four beeps close the throttle and you will hear two beeps Itis stored in memory until you want to change it again It has a Battery Elimination Circuit BEC but the instructions have no recommendations on the maximum number of servos you can use I would err on the side of caution and not use more than three It has one feature I really don t like Instead of a discreet beep or two when you connect the drive battery 1t plays a daft tune that gets everyone patting their pockets thinking their mobiles are ringing There was no information on suitable propeller sizes so I did a bit of bench testing to get some idea of what to use The batteries I used were 25 and 3S 1500mAh Kokam LiPo Propeller 25 LiPo 3S LiPo 6 x 4 7 2V 51A 10 8 8 9A T x4 6 4A 10 6V 11 0A 8 x 4 3 6 6V 8 5A 9 8V 14 5A As you can see the numbers are comparable to Speed 400 motors except that the last high current one 1s way above what a Speed 400 could handle At no time did the speed controller feel hot and even the high voltage high current run didn t seem to bother the motor got no way to measure the efficiency but it s got to be better than Speed 400s that normally peak at 6096 Right let s nail i
38. fitting some of this new technology The Mercury Matador I have a vintage Mercury Matador built from the Ben Buckle kit I really built it as a tribute to my dad In the 1960 s when I was a boy my dad built one of these from the original Mercury kit He knew little about aircraft but loved electronics and radio I just liked planes Radio control equipment was a huge challenge at that time To afford it you had to build some yourself My dad built a Hill Mark 2 transmitter and receiver The transmitter was much too big and heavy to hold it sat on the ground The transmitter aerial was eight feet long an army surplus fighting vehicle antenna It carried a 120 volt 80 cell high tension dry battery The receiver sported two thermionic valves When switched on you could see these glowing through the cabin windows This receiver plus some heavy flight batteries made the model somewhat hefty even when built lightly and tissue covered This model lasted for one flight damaged due to hard impact with a ploughed field but it did fly and sat nicely in the air My new Matador was built in the early nineties for electric power The motor is an MFA Olympus 540 brushed motor with belt drive Covering is Litespan Control is rudder elevator and motor The battery was 1250mAh 7 cell NiCd E F U K 33 This combination produced many good flights but the model has always felt a bit heavy I never really reached that guided free
39. flight feeling Also the flights seemed to need full throttle all the time so were a bit short Recently I replaced this NiCd with a 2 cell 10C 2000 mAh LiPo battery from All Electric RC having established by measurement that the motor draws about 18A just below 10C which is 20 amps at full throttle when lightly propped with a 10 x 6 wood I also fitted Jamara LiPo Fly 25 speed controller This combination added several ounces of lightness and has noticeably changed the model s flight characteristics It now ambles in the air and can be trimmed for nice spiral climbs and descents a la free flight This model has been saved from the bring and buy sale I do not think I am at the end of the adding lightness road with the Matador I feel a small brushless outrunner motor matched with a smaller LiPo battery somehow held in the nose cowl to preserve Centre of Gravity could be worth a try The Sopwith Pup As an avid park flyer I have had many happy hours using a well tried combination of GWS models Pico Stick then Cub and Overlander 300 mAh 7 cell NiMH batteries I was getting to a stage where I wanted to try some more difficult scale subjects Also the NiMH batteries were getting very tired after several seasons and needed replacing The first difficult subject I tried was Kavan Sopwith Pup park flyer Thisisa very nice kit all pre coloured Depron Lots of wooden struts even
40. from 10 00 BBQ amp Raffle More at www phoenix mfc freeserve co uk BEFA ElectroSlot and E400 League event at Billesden For the location or more information contact David Perrett on 01455 272 297 or by email at d l perrett btinternet com 2006 Militky Cup Pfaffikon Switzerland Open International Non World Cup Event for F5B Motor Gliders and F5F 10 Cell Motor Gliders See www silentwings ch or contact Emil Giezendanner Feldstr 25b 8330 Pfaffikon Switzerland Tel 41 43 288 84 30 Fax 41 43 288 80 33 or emil giezendanner modellflugsport ch Hayes amp DMAC West London Fly in at Cranford Park Hayes Contact David Chinery at DavidDchinery aol com for more info BEFA ElectroSlot and E400 League event at Leamington Spa OS Grid SP 3187 6779 For more information contact David Perrett 01455 272 297 or by email at d L perrett btinternet com Rolls Royce Hucknall MAC electric fly in at Hucknall airfield near Nottingham M1 exit 26 Pilots and helpers only Proof of insurance and A Certificates required For further details call Neil Barnard on 01332 516 192 or Barry Parkinson on 0115 973 1954 E F U K 59 18th Southern Area Electric Fly In at the Winchester MAC site See poster on page 62 for more details 24th 25th Wings amp Wheels at North Weald Airfield Nr Epping Essex CM16 July 2006 1st 2nd 2nd Oth 23rd 23rd 6AA See page 10 for more details Middle Wallop Fl
41. g field One of my first models was an IFO which I can fly in my garden and was purchased when they first arrived here My recent I C flying had mostly been sport aerobatics with the usual Acro Wot OS 91 5 and scaled down versions Milli Wot with OS 26FS and a Micro Wot with an OS 15 Thus I am always looking for fairly high power weight ratio The IFO seemed rather underpowered and the agents were offering 7 8 and 9 cell battery packs so I uprated from the 8 to 9 cell pack with very little 1mprovement I investigated this problem and found that at full throttle the battery voltage was down to 6 4V an average cell voltage of just over 0 7 V The motor was a 280BB with a 3 7 1 gearbox and a 10 x 4 7 prop I further investigated and found that the cells used were quite inadequate in current delivery terms and substituted 8 x Sanyo 600AE cells which cured the problem I sent an email to the supplier pointing out the problem which was duly ignored but I noticed that they changed to 600AE cells shortly afterwards Last year I bought a Protech Ultimate Shock Flyer fitted it with an AXi 2212 34 and a 700 mAh 3S1P LiPo battery Unknown make but claimed to be 100 and found it flew well enough but felt it could do with more urge I bought another battery really because I needed two this time a Kokam 720 and found a pretty significant increase in performance E F U K 37 As I wanted couple of batteries of the same performa
42. ip Do an initial test run on the motor with no prop fitted It should run up smoothly and quietly with no vibration Direction of rotation is easily changed by un plugging any 2 of the 3 wires and swapping them over 13 Bench Testing One of the likely uses of this size of motor will be with 7 cells where 7 NiCds or NiMH compare favourably with 2 LiPo cells or 8 cells E F U K 53 To this end the testing was conducted using 7 cell and 8 cell NiCd pack with suitable propellers DIY BRUSHLESS OUTRUNNER 400 10 13 WIND ON A HACKER OPTO 40 3P SPEED CONTROLLER 8 Cells Propeller Current RPM Thrust Approx Speed A oz mph 5 5 Microspeed 9 6 15 000 10 3 75 5 x 3 Master Airscrew cropped 8 4 15 460 10 3 46 5 x 4 MA 8 0 15 400 9 1 62 6 x3 MA 9 6 14 780 12 5 44 6 x 8 5 9 6 14 520 11 4 51 6 x 4 8 9 14 730 10 3 59 T x 4 Graupner 15 0 11 800 13 7 41 7 Cells Propeller Current RPM Thrust Approx Speed A 07 mph 5 x 5 Microspeed 7 3 13 120 6 8 66 5 x 4 MA 6 3 13 700 6 8 55 6 x MA 7 6 13 400 9 1 40 6 x 3 MA 7 8 13 210 9 1 46 6 x 4 7 5 13 420 9 1 54 T x 4 Graupner 13 7 11 350 12 5 45 Conclusion The motor is fairly cheap to build and was certainly satisfying in the end result The 18 wind version seems suitable for what I need it for although I can easily rewind the stator to make changes later Any further
43. lanced position run some cyano between stator and bearing tube and between solder connection plate and bearing tube The completed stator can be carefully withdrawn and the wires soldered through the holes in the plate 11 A Slight Adjustment On trying to assemble the motor I found that the stator and rotor were rubbing This was rectified by mounting the stator assembly 1n the bench drill and filing 52 E F U K some material off the crests of the stator lobes Use magnets that are 1 5mm thick and you will avoid this problem 12 A Finished Motor Now running with satisfactory clearance the connection wires for the speed controller have been soldered onto the solder plate For small motors where the stator is only one section of 5mm length John indicates that the magnetic field alone is sufficient to counter the thrust at the propeller and prevent the motor pulling apart For this one with a 10mm stator I will cyano a 10mm length of brass tube to the rear end of the drill blank leaving a whisker of clearance between the tube and the rear ball race This will be permanently fixed but this motor can be disassembled from the front if the stator windings need to be modified at any time For mounting in a model carbon fibre tube can again be use With an inside diameter of 8mm and saw cut through the wall for distance of about 12mm in the CF tube can be clamped to the bearing tube with a small hose cl
44. me temperature as near as possible to 35 40 C before carrying out comparative tests The obvious mistake to avoid is to compare a just charged Lithium battery with a NiMH pack which has just been fast charged and is hot off the charger A good demonstration of the comparison of three notionally similar batteries 1s the results obtained from the three 700mAh lithium batteries which originally led to the instrument They are all 3S1P LiPo packs one of unknown make one a Kokam 720 and the last a Kokam 730 E F U K 43 Rather than table of results a comparative graph showing efficiency and the two power figures has been plotted for all three battery packs 100 All packs were 3S1P 90 ee Sete wes Kokam 740 Kokam 740 80 n Kokam 720 70 n Efficiency 2 Kokam 720 Po Power Output P Power Loss 60 n Unknown e Po Unknown P Unknown Efficiency cn P Kokam 720 oe 20 P Kokam 740 0 5 Current A 10 15 The above shows how the unit will compare any two packs the only problem is that you need to have both of them in your possession It is noticeable how widely the performance of Lithium batteries vary assumedly because the technology is new and some manufacturers have developed better techniques than others NiMH batteries on the other hand vary much less presumably because the manufacturing technology is more mature an
45. nce I tried to buy another but Alan Fry talked me into a Kokam 740 probably because he hadn t got any 720 s left This absolutely transformed the performance of the model This set me to thinking that there must be a way of objectively quantifying the widely varying performances of apparently similar batteries If you ask around for advice however well intended it is always subjective and must be distorted by other variable factors such as motor propeller aircraft weight or whether the advisor is actually trying to sell you batteries What I wanted was an objective instrument which would just read out performance I should make it clear here that I wanted to measure the ability of batteries to deliver current not their ability to store energy 1 e flight performance not flight time In car terms the intent would be to measure acceleration and top speed not m p g and tank capacity We are all aware that the ideal battery would have a completely stable output voltage capable of delivering infinite current without any voltage sag at all In our real world every cell whatever it s chemistry has some series resistance built into it ESR Equivalent or Effective Series Resistance and it is this which causes the voltage sag or drop at the battery pack terminals 38 E F U K It also results in the heating up of the battery pack by the wasted energy which we would much rather went to the motor We can quantify this
46. nd for 2 3 Lithium cells The spinner is 30mm diameter and the length is 43mm with a weight of 30g including the mount The maximum rating 18 for 30 seconds and the recommended model is 300 600g This motor is intended for 6 x 3 or 7 x 4 blades not included and costs 34 95 The 500 is 1200 rpm v and 1s also for 2 3 Lithium cells The spinner is 40mm diameter x 50mm long and weighs 51g including mount The maximum rating is 15A for 30 seconds and model weights 400 800g This motor is suitable for 7 x 4 8 x 4 or 9 x 5 blades The HCS C Compact 500 Spinner not included and costs 34 95 Outrunner Motor The 700 1s 1485 rpm v and 1s also for 2 3 Lithium cells The size 1s the same as the 500 and the weight 58g including the mount The maximum rating 1s 20A for 30 seconds and the recommended model is 600 12002 This motor 1s designed for 8 x 6 9 x 5 10 x 6 or 11 x 8 blades not included and costs 39 95 Also now available from Robotbirds are pair of light weight 25mm diameter plastic wheels complete with aluminium axles The wheels are solid plastic 1 e no tyre The axle part 1s designed to fit onto the end of a 2mm carbon rod making them an excellent solution for shock flyer type 1 E More information on these or other Robotbirds products can be found on their internet shop site at http robotbirds com catal
47. ngth were the motor and undercarriage plugs in and the foam 1s quite dense but light Removing the motor was not easy as it glued in with some silicon like substance The foam was then cut away to take the new motor ensuring the built in down thrust was retained 30 E F U K small LiPo capable controller was soldered on and then stuck to the fuselage wall with the battery connection out through a small hole just in front of the lower wing The RX is a tiny unit from All Electric RC at 15 which has a short thin aerial and was fitted just above the bottom wing A single Tower Pro SG 50 servo was tried in various positions to get the balance right and finished up just behind the TE of the top wing A short wire link was fitted to the tape hinged rudder The linkage could have been internal but is more accessible as itis The model was re assembled awaiting the delivery of a 281P 145mAh LiPo from Alan Fry During this time a longer undercarriage was made to give more ground clearance to the bigger propeller The propeller is 5 black plastic which features separate blades in a small hub The gearbox has a quite long built in propeller saver With this combination the current is only 0 4A but a reasonable draft is produced and it scuttles along the garage floor at a good rate A G nther prop was also tried but did not seem so good I fitted the 145mAh LiPo under the bottom wing with Velcro and the CofG came out on the LE of the t
48. nternet access contact me for how to get hold of John Also included with the 2 large plan sheets shown above are a comprehensive set of building instructions These include some photographs to assist in illustrating key points were required Specification Wing Span 52 0 1n 182 cm Wing Chord Root 13 5 1n 34 9 cm Wing Chord Tip 12 5 1n 31 8 cm Fuselage Length 50 0 1n 127 cm Wing Area 676 sq in 43 6 dm Dry Weight 26 oz 0 74 kg AUW Prototype 48 07 1 36 kg Wing Loading Prototype 10 2 oz sq ft 31 2g dm Electric Flight Calendar If you would like details of your event to appear 1n these pages please send full details to the Editor EF UK contact details on page 4 Please bear in mind that this magazine is quarterly so ensure that the details are sent in good time For last minute information on events please check out the events list on the website www befa org uk Dates times and even locations of events can change at the last minute You are strongly advised to check on events with the given contacts before setting out on your Journey to any event All BEFA flying events require proof of BMFA or equivalent insurance and an A Certificate to fly For fixed wing models any of the fixed wing A certificates are acceptable For helicopters a helicopter A certificate is required flying models must have been satisfactorily flown at least twice since build or repair before flying at a B
49. og 6 E F U K Aurorra Ltd have recently added 2 data logging devices to their range of products the DPR 50 and DPR 100 These are designed to be fitted to your model between the battery and controller to record current and voltage data in flight The specifications are Very small 1 2 x 1 6 80 x 40 mm Very lightweight approximately 0 9 oz 25g Accept a wide range of voltage inputs 7 to 30 Volts Digitally record up to 9 hours of flight data e Records and graphs in use o Current draw up to 50A DPR 50 or 100A DPR 100 Power output up to 1500W DPR 50 or 3000W DPR 100 o Amount of charge used o Battery efficiency voltage drop under load o Elapsed time of each mission o 2 independent temperatures using a dual probe sold separately Configurable o Data sampling rate o Recording trigger o Channels to record o Computer graph displays with provided software o Recording resolution Very easy to set up and use Each DPR package includes the Digital Power Recorder DPR 50 or DPR 100 a3 ft 1m USB A to Mini B interface cable and gt CD ROM with powerful DPR graphing amp software USB support files and soft version of the user s manual The DPR 50 is 70 00 the DPR 100 is 83 43 and the dual temperature probes 1s 10 58 Aurorra can be contacted at 108 Wheel Lane Grenoside Sheffield 535 8RY by telephone on 0114 257 0401 or through their website at w
50. ollowing pages are photographs of the best bits Many thanks to farmer John Lewthwaite and helpers for a lovely day out which is not to be missed I hope to see you all next year Richard Jones flew all of his EDF jets 22 E F U K p Above This Old Timer electric conversion flew well Below lovely Hawker biplane but the owner left before lunch after oly I flight Above David Orme s 8 span stunter Lancaster and Sea Fury mostly out of shot Below Tim Hooper 5 airforce with special Lysander ae Above Another view of Tim Hooper s airforce including an interesting Quadriplane Below Tim Hooper with his French 3 engined model y lt a i i j AY ASK 2 Above Nice line up of COVER powered RUE by TM Tong Below Bob Moseley s exotic German kit flting wing 9 span flew exceedingly well Above Richard Few amp Josh Spiers arrived early with their models Below Andrew Aske and his F 16 Above John Shorthorne brought his red Formula stunter Below A Lanzo Bomber built by Ray Haynes LLOVLE 92610 euoud MMM je opio a TTF Bz MOI 3215 duiejs oBejsod AG AS sjapow 4 4 JO 9 20 ajqeyings pue peeds 2 YDUNE esf uo2es Jad 0 sejduies p
51. only leads you should extend are the ones between the motor and the controller Don t forget to pull out the red wire on one of the receiver connectors or the two BEC circuits may start to fight each other with dire consequences The instructions warn against extending the leads between the controller and the battery to more than 200mm total The reasons are complex but basically long battery leads will let the smoke out of the controller So don t let the smoke out what d he p say PHUEWI Pulled Hard Up Elevator While Inverted think E F U K 21 Pillerton Hersey 2005 by Robin Andrew Once again we had nice weather although the forecast had not been good By lunch time 30 cars had eventually arrived This included new visitors Tim Hooper David Orme and John Shorthouse who used to be large petrol model flyers and Andrew Aske with his F 16 This made sure we had models flying all day Some exceptional gliding flights made by a 9 2 75m span flying wing built from a German kit Personally I love to see Old Rubber models converted to electric power and several turned and flew well I awarded my Scale Cup to Tim Hooper for 2 lovely flights with his Bristol Freighter He also flew other scale models that were in contention including a 3 engined French freighter Stalwarts Richard Jones EDF Richard Few Josh Spiers and Alf Andrews did their usual super flying displays On the f
52. op wing which luckily seems just right At an overall weight of 3 7ozs 105g I have a true wing loading of 2 4 oz sq ft 7 4 g dm The test flight was not a success with the model being underpowered I need to consider options for improving the power available Learning to Love LiPo s by Brian Rawnsley For the last two years or so the sport flying end of the electric flight scene has been revolutionised by two new innovations Trips to the BEFA technical workshop and a look round the trade stands convinced me of this The two new innovations in question are Lithium Polymer LiPo batteries and small affordable brushless motors and controllers The electric flight press and motor calculation programmes give many facts and figures about these devices For my own use I have boiled these down to some simple rules of 10 and 20 10 minutes is a good time of flight for a sport RC model This gives time to complete a number of manoeuvres circuits and bumps or whatever Then as a pilot I feel it is time to land chill out change the battery chat about the flight and prepare for the next one 20 pounds is an affordable price to pay for any individual piece of in flight electric or electronic equipment By individual piece of equipment here I mean a motor a speed controller a battery a receiver or a servo For LiPo batteries I think it boils down to having a battery capable of delivering current at ten
53. or having a capability of at least 15A at 8596 efficiency This makes the brushless motor over twice as good as the Speed 400 and it would also be lighter John s article indicated that a motor built from 2 stators stacked together would be about right for my requirements The finished weight was 1 602 half the weight of a Speed 400 Parts required You will need 1 A speed 400 motor new or used 2 Twelve Neodymium magnets 12x 4x 1 5mm These are available from George Mizzell Engineered Concepts 1836 Canyon Rd Birmingham AL 85216 USA www supermagnetman com These currently cost 60 cents each for up to 49 magnets with discounts for larger quantities and delivery 1s very fast Payment can be by PayPal credit card to fax 1 205 823 5607 of in US Dollars by cheque or cash 46 E F U K 3 Two stators 9 pole 22 7mm diameter at 85 each from C amp K Designs 14 Queen Elizabeth Dr Corringham Essex 5517 7TH www brushlessmotors co uk 4 Asolder connection plate This is not essential but makes the winding connections much neater 95p from C amp K Designs 5 Two ball races 0 125 x 0 250 RS Components part no 747 614 6 Adrill blank 0 125 diameter at about 1 12 available from Drill Service Horley Ltd Albert Road Horley RH6 7HR tel 01293 774911 www drill service co uk 7 Alength of 8mm OD tube carbon fibre or aluminium alloy 8 Insulated winding wire 0 4mm diameter suited my motor 0 5
54. ose with Internet access may visit the B E F A website at www befa org uk where you will find all the membership information you should require and a application form E F U K 65 B E F A Sales BEFA Round Coloured Rub down Decals Ultra thin amp light 50p each EF UK Back Issues Issues 71 to 73 and 75 to 88 are available to members at 3 00 each or 5 00 each to non members These prices include UK P amp P overseas rates on application Reprints of earlier issues may be available to special order at slightly higher cost contact the Editor for details see page 4 EF UK Index A comprehensive index of EF UK from issue 28 to date is available by sending a 1 coin to cover copying and postage cost Binders are available to hold 8 to 12 issues of Electric Flight U K Produced in dark blue with gold lettering on the spine these cost 4 50 each including U K postage Please add 1 for European postage and 2 for Worldwide postage Please send all orders to The Editor of EF UK at the address on page 4 Sweat Shirts amp Tee Shirts Stock of these 18 now almost all gone please contact Robert Mahoney regarding remaining stock sizes and prices PLEASE REMIT IN STERLING ONLY WITH ALL CHEQUES MADE PAYABLE TO B E F A Advertisers Index BERA Sale ROM 66 eT a LS Eos e E E Inside Back Cover MOI Aled Wanto 63 Hyper URC 29 NO 6 to 10 RC Groups E Zone
55. otographs can be emailed to the Editor at editor befa org uk Readers always like to know what equipment is fitted to models so they know what combinations work well or not so well Therefore please include as many details of the models in the photographs as possible but ideally at least wing span wing area motor s gearbox es propeller s or fan s battery pack s used amp the flight performance Where articles are produced on a word processor package please include an electronic copy it make the Editors job much easier and quicker Ideal formats are Microsoft Word any version Works word processor WordPad or Notepad Other formats can be accommodated but please contact the Editor first E F U K New to ELECTRIC FLIGHT START HERE You may be taking up Electric Flight for the first time or you may be converting from another discipline Whatever your situation help and advice is available BEFA has prepared an information sheet which details further sources of information which you may find useful when just joining the hobby To receive a copy please send a Stamped Addressed Envelope S A E to Robert Mahoney address on page 4 BEGINNER S GUIDE A Beginner s Guide to Electric Flight is available which explains many of the Mysteries of Electrics and will hopefully set you off on the right foot Please send 3 00 per copy required to The Editor of EF UK at the address on page 4 Please add 1 00 ext
56. r 3 bladed 10 x 5 These all give approx 175 200W at 25A 28A in flight 40A static 8 E F U K Editor I think the Aero Master would be excellent with a 8S LiPo pack more power and lighter weight at the same time When using a 3 bladed propeller with this model the Aero Naut 3 bladed precision hubs and spinners are an excellent choice The Aero Master should be available through all Aero Naut stockist at around 160 This issues final items are Aero Naut Precision Hubs amp Spinners mentioned above The 2 bladed version 15 available in 36mm 38mm 40mm 42mm amp 45mm spinner diameters for 4mm 5mm or 6mm shaft sizes They are supplied as a CNC machined Aluminium base plate a M8 collet a k Impact resistant plastic cap and retaining screw 7 In addition to the spinner a standard Aero Naut A folding propeller yolk to suit the spinner is required The price for the 2 bladed hubs should be approx 11 to 15 with the yolks being around 5 8 The 3 bladed version 1s available in 36mm 42mm or 65mm diameters also for 4mm 5mm or 6mm shaft sizes An Aero Naut 3 blade propeller yolk 1s also required The 65mm spinners are designed for use as a non folding sf propeller The 3 bladed spinners should be around 13 to 18 with the 3 bladed hubs being approx 10 12 E F U K 9 402 AAS PAHU E Sit ssi euo2 e
57. r publication of this magazine If you can check them out at www befa org uk E F U K 3 BEFA Committee 2006 7 Chairman Secretary EF UK Editor Webmaster South West Representative Treasurer Membership Secretary Northern Representative Events Co ordinator Competition Secretary Midlands Representative Welfare Officer Southern Representative Indoor amp Free Flight Rep Technical Liaison Officer Public Relations Officer Safety Adviser Robert Mahoney 123 Lane End Road High Wycombe Bucks HP12 4HF EMail befa rlmahoney co uk Jan Bassett 111 Plantagenet Chase Yeovil Somerset BA20 2PR Tel 01935 472743 Email secretary befa ef uk net or editor befa ef uk net Bob Smith 1 Lynwood Avenue Tollesby Middlesborough Cleveland TS5 7PD Email bob smith007 ntlworld com Terry Stuckey 31 Dysart Avenue Kingston upon Thames Surrey KT2 5QZ Email terrystuckey blueyonder co uk David Perrett 10 High Lees Sharnford Leicester 3PW Tel 01455 272297 Email d l perrett btinternet com Roger Winsor 14 Butler Gardens Market Harborough Leics LE16 9LY Email Rogerwinsor7 aol com Dave Chinery 251 Station Road Hayes Middx UB3 4JD Email DavidDchinery aol com Gordon Tarling 87 Cowley Mill Road Uxbridge Middx UB8 2QD Email gordon tarling ntlworld com Alan Bedingham 17 Highcliffe Close Wickford Essex SS11 8JZ Email bbba18333 blueyonder co uk John Thompson 19 Park Aven
58. ra for overseas postage and remit in Sterling Cheques should be made payable to BEFA TECHNICAL HELP SERVICE Technical help is now available again for the use of all members We regret that no telephone service is available but all questions in writing or email will be answered by our Technical Liaison Officer TLO Please refer your queries to our TLO to the postal or email address on page 4 If sent by post please ensure that you include an S A E for a reply CONNECTIONS SERVICE Requests are frequently received from members who wish to be put in contact with other members living in the same area The easiest method of doing this 1s to place a free wanted advert in the classified section of this magazine Alternatively a request may be made IN WRITING to the Membership Secretary who is allowed to divulge such information to members ONLY Please supply as much information about your location as possible and please remember to include an S A E for your reply B E F A MEMBERSHIP Membership of the Association 1s open to all Those who are not members of BMEA our national controlling body will have a subscription to EF UK membership with none of the other benefits Overseas members are very welcome and will be classed as full members if they belong to their own national controlling body CONTACT For full details please send an S A E to the Membership Secretary address on page 4 requesting a membership application form Th
59. re Sanyos 760g and Konions 548g Interpretation of Results The displayed results show that the two packs are very similar 1n performance both in efficiency and in delivered power This is because the ESR of the two packs 18 extremely close with a very similar off load voltage The calculated results show that the Konions have a 45 advantage in power weight ratio I also took figures at 40 C which is a more realistic operating temperature and they showed a 14W increase in power for the Sanyos and 20W for the Konions The reason for this 1s that the curve of the temperature coefficient of ESR 1s steeper for the Konions than it is for the Sanyos You might look at the above comparison and say So what as the figures are very close This is only coincidence in this particular case Comparing other batteries has thrown up differences of 2 1 with efficiencies dropping alarmingly at higher currents When you retrieve your model after a flight and notice that the batteries are up around 40 50 C you should think to yourself All that energy wasted which should have gone to the prop To quantify this I took results from an 8 cell pack of good quality Sub C NiMH cells from 10 80 and this is on the next page 42 E F U K Current Efficiency Motor Battery Loss Amps W W 10 95 4 97 4 20 91 0 186 17 30 86 6 267 40 40 82 2 337 72 50 77 9 399 112 60 73 5 452 161 70 69 3 497 219 80 65 0 533 285 Note that the power lost in
60. stall probably to ensure a tight turn The week after the word had got around and Maplin had sold out but we did get a few later at an even cheaper price when a toy chain was closing down Some have had problems with the tiny charging socket Recently I gave a lunchtime talk on electric flight to the local Rotary Club and finished off by flying mine around the dining room We have also flown them at the Pontefract and Dewsbury Club meetings Dewsbury Clubmate Doug Potter always the innovator has removed the guts and fitted them into a stick model with larger Depron wing In doing so he discovered the whole model is powered by ONE 145mAh LiPo His model needed quite a bit of tweaking before satisfactory turning was accomplished but eventually by lowering the pylon and towing the pusher motors out he has been successful E It would seem that a lot of thought has gone into this design the soft nose and pusher props make 1t safe The contra rotating helps to give direction stability and the short span of the biplane wing improves the turning rate Editor maybe we can get a plan for a future issue I ll see if I can arrange something 17 TLC from your By Alan Bedingham It s not often I have to eat my words and rarely so quickly You may remember a couple of issues back I was discussing different types of motors and when I got to brushless motors I suggested that 1t wasn t worth bu
61. t lieri gar Eganen UR ma ha N E MORE REVIEWS 1 N The Aircraft Plans and Construction Guide NOW 4 95 p amp llar se haie for zs y Hace 0 4 THIS IS ONLY A SMALL SELECTION OF THE PRODUCTS WE HAVE AVAILABLE CONTACT US TODAY FOR A FREE PRODUCTS CATALOGUE OR CHECK OUT OUR WEBSITE www traplet com a ps ima alg EIE AR subscriptions wii commence wel yn pee a s ba sn hag vu cha xi mani Toit per per plans
62. t to my poor battered old Picostick and fly it I started with a 28 1500mAh LiPo pack and a 7 x 4 propeller Pretty good performance actually it would climb quite briskly compared to the standard GWS geared motor touch and goes were a breeze on our grass field and the plane felt much more lively The only down side was that the wings were bending more than usual because of the extra weight In for a penny in for a pound let s try the 8 x 4 3 propeller Blimey never seen a Picostick go vertical before Loops were easy any size I liked I even got it to roll Then my luck ran out I was setting up a landing approach on the second flight 1n quite gusty conditions when one of the cane rods that holds the wing to the stick broke It went in from about six feet up and that was that All the expensive bits survived OK but it was RIP time for my Picostick Next step is to put it in my Nigel Hawk I need a different motor mount for this and I ve seen a bulkhead mount for 1 50 that ll be just the job ll let you know how I get on when the weather gets good enough to go flying I used to go flying in all weathers when I was working now I wait until it gets reasonably warm knowing I can fill my boots This retirement lark is the best job I never had Editor Go on then rub it in By the way if you re thinking of putting two of these in something like Twinstar remember you need a controller for each motor and the
63. te to fly For more information contact David Orme on 01543 686 230 11th FAI World Electric Flight F5B amp F5D Aeromodelling Championship organised by the Romanian Modelling Federation The contacts are Mihail Zanciu nzanciu modelism mceit ro and Marius Conu mconu modelism mcit ro Postal address OP6 CP 56 Bucuresti Romania Telephone 40 213 162 454 and Fax 40 213 162 454 E F U K 20th Woodspring E Fly 2006 at the Woodspring Wings Model Airfield in Yatton near Bristol As much a fly in with interested visitors rather than a show No entrance fee just 5 00 per car for parking For more see www woodspringwings co uk efly html or contact Bob Everitt on 01275 842 651 or email bobeveritt tiscali co uk September 2006 ard BEFA Hayes Fly In at Cranford Park Hayes Middlesex For more information contact David Chinery at DavidDchinery aol com 10th BEFA ElectroSlot and E400 League event at Billesden For the location or more information contact David Perrett on 01455 272 297 or by email at d l perrett btinternet com 16th 17th ASPACH at MFG Aspach e V 71546 Aspach Details by email from info mfg aspach de or internet www mfg aspach de You can also get more from Robert Mahoney at robert rlmahoney co uk 17th Pillerton Hersey Fly In Come and have some fun at this relaxed event All electric flyers welcome amp only 2 to fly proof of insurance required More details from John Lewthwaite on 01789 740 688 24th
64. ue Liversedge West Yorks WF15 7EQ Tel 01924 515 595 Eemail johnty99 ntlworld com David Beacor 34 Chestnut Close Brampton Huntingdon Cambs PE28 4TP Please enclose an SAE with all correspondence to the committee 4 E F U K Chairman s Chatter Dear members I must first start with a thank you for all the good wishes I received after my short illness I was at our AGM for a very short time 30 minutes to present John Lewthwaite with his life membership This was given to John for his support to Electric flight in the UK and to BEFA in letting us use his flying field for our competition events over many years The Middle Wallop fly in 1 amp 288 July will have all channels available on both days There will also be a free pilot s raffle on the Sunday for pilots who fly their models that day The 2006 membership renewal form should be enclosed with this issue if for some reason it is missing please download one from the website or contact Bob Smith I am sorry this 1s a short chairman s chatter this time KEEP THE WATTS UP Robert Mahoney Current Lines from the Editor Well this was to be my 20th and last issue however I ve been asked and agreed to do one more issue by the new Editor Jill Day is she 1s unable to take over the reins until June Due to this left my details against the post for this issue so that items are sent to me Jill s address to be substituted in the next issue
65. ue ejep 6 0 dn 5 m ydd 10 1no uo s ejdsip pue 5 104 ANV sna ay seonpoJjjul 029 E F U K Staggerwing Conversion by John Thompson CC Lee make a series of beautifully crafted foam electric free flight scale models for Perkins at around the 15 mark and reports say they all fly well Even the Spitfire 1s capable of Out Of Sight flight from a one minute charge of the internal battery I bought the 20 51 cm span Beech Staggerwing few years ago and the first free flight ended up in a tree about a half mile down wind Recently with the advent of cheap micro radio and the start of our indoor season an RC conversion was considered At the BEFA AGM I had bought a small planetary geared motor from Steve Metham s stand at about 12 and this would fit perfectly in the radial cowling The model comes ready to assemble and everything 15 attached with double sided tape The fuselage 1s a top and bottom moulding joined already with a trim tape and as I was concerned about spoiling the painted finish this was slit open with a sharp scalpel I should have been more careful hear as there are locating pegs and sockets inside On the inside were a direct drive motor three tiny cells and PC board with charging socket switch on it The mouldings are superb with extra stre
66. w applying to the battery losses Unit concept Although the unit would produce an efficiency figure for the chosen current it seemed to me that the other parameters of immediate interest to us would be the power going to the motor and to drive home the message about losses the power lost in heating up our batteries It was therefore decided to attempt to display these three figures for any chosen operating current Using the same techniques that I had used in the ESR meter I could derive both on load and off load voltages and put these 1nto memory Having an accurate analogue of the current used in the measurement it was therefore possible to multiply this by the on load voltage to give the power delivered to the motor and to also multiply 1t by the difference of the two voltage figures to give the power lost in the battery The current pulse applied to the battery has to be accurately controlled and independent of the battery voltage so that several large power FETs in parallel are used driven and controlled by an operational amplifier Experience with the ESR meter had demonstrated that all batteries have a significant temperature coefficient and it is therefore important that the testing itself does not heat up the battery The ESR meter operated on a repetitive pulse principle with the output voltage being updated every second Although this was a very small duty cycle 1t still eventually warmed the battery and distorted ESR
67. ww aurorra co uk E E F U K E Also now stocked by Aurorra is the FMA Direct ___ m OPTO4 4 channel opto isolator This unitis intended for use in models with long servo cables to ensure that any interference picked up in the servo lead is not transferred to the receiver It features twin battery inputs one for the receiver and one for the servos The unit is 1 95 60mm long weighs only 0 4 oz 12g and costs 35 25 Recently introduced by Aero Naut 1s the Aero Master which 1s a development of the highly successful Aerofly The new kit features a taller GRP fuselage which can now accommodate a much wider range of power systems as there 1s clearance for up to 10 diameter propellers The wings panels are supplied factory assembled and are of built up construction fully sheeted 1n balsa ready for covering or painting The modified MH 32 wing section allows a broad speed range The kit contains comprehensive building instructions general arrangement plan GRP fuselage ready made wing panels all wooden parts internal formers and miscellaneous items The wingspan is approx 2 5m 982 length 1 15 m 454 wing area 45 5 dm 705 sq in and weight with 8 Sub C cells is around 1 75 kg 61 oz The model is designed for Rudder Elevator and Motor control recommended motors for 8 Sub C cells are Actro C6 with 10 x 8 or 3 bladed 10 x 6 Actro CL5 with 3 bladed 10 x 8 or Actro CL4 with 10 x 7 o
68. y In Possibly the largest electric event in the UK This year there will not be a league event on the Saturday so all 35MHz frequencies will be available on both days Electric Flight traders are extremely welcome at this event Unfortunately 1t 1s not possible to camp on the site but there are camping sites in the local area For more details contact befa rlmahoney co uk Ebor Silent Flight meeting on the York Racecourse Chester Roodee Electric Fly In BEFA ElectroSlot and E400 League event at Leamington Spa OS Grid SP 3187 6779 For more information contact David Perrett on 01455 272 297 or by email at d l perrett btinternet com Bath SpaRCS Electric Fly In at RAF Colerne Wiltshire Airfield site with tarmac runways and grass No competitions Proof of BMFA insurance required Regret no facilities for spectators Pilots briefing at 1000 For more information contact Bob Partington 01225 891 441 or email bob partington ukonline co uk August 2006 6th 13th 13th 18th 26th 60 BEFA Leamington Spa Fly In contact secretary befa ef uk net for more information BEFA ElectroSlot and E400 League event at York OS Grid SE 6210 6030 For more information contact David Perrett on 01455 272 297 or by email at d l perrett btinternet com Fradley Airfield Electric Fly In just off the A38 between Lichfield and Alrewas 10am to 5pm Tarmac runway Electric Fixed Wing only and they require BMFA membership and A certifica
69. y the process It was interesting and enjoyable making sure that everything fitted exactly as 1t should and that the drawing made sense for some one else to follow The history of the Sprite started back in June 2002 after buying one of the then fairly new to the Market AXi 2820 10 motors I remember at the time reading a report on the Actro Motors and being very impressed with their performance and 56 E F U K equally as impressed with their cost Seeing the AXi on the Puffin Stand looked to be a good compromise and more suited to my pocket At that time the model was designed around 10 x 1700 cells and it performed well ona 10x 6 with an all up weight of about 3lb 6 ounces I had decided on a fairly mid fuselage position for the wing so that it was always a bit of a fiddle to get the wing 1n situ with all the wires protruding through for the battery hatch etc It was at Chester last year that I was tempted to purchase some of the Li poly s on offer by the All Electric RC Company stand as for 60 at the time for a 8 cell pack at 11 1 and 4000mAh seemed like too good a bargain to miss The financial controller was 1n agreement so money changed hands By substituting the 1700 with the Li poly made a huge difference to the performance of the model Shaving nearly 6 ounces off the original weight the performance and duration was really more than worth the cost of the batteries Having been so pleased with the performance I decided to make
70. ying little ones to replace Speed 400s because the cost for a big motor wasn t much different Well found a brushless outrunner and speed controller combination that will work in Speed 400 models and that you can get for around twenty quid I got mine from RCM Direct and I paid thirty quid of course mind that was a while ago Looking in the latest mags the price has dropped to around twenty quid just my luck How do they doit I know labour must be cheaper in China but I just can t work out how you can make these two for twenty quid let alone ship them halfway around the world and still make a profit I was in a florists the other day buying some flowers for er indoors got to keep on the right side of she who holds the purse strings you know and they were telling me that most of their flowers came from Colombia Colombia That s crazy how can it possibly be economic to ship perishables like flowers 5000 miles Am I the only one who s bewildered by it all Sorry down to business with a review of the little beast 18 E F U K The label says Bm2408 21 which I suspect can be translated as a brushless motor with a 24mm diameter and 8mm wide stator wound with 21 turns In other words the usual gibberish that s no use to us I would call it a 140 3 1 e 140W and 35 Lithium maximum 35 Lithium 1s for those of you who haven t been paying attention at the back there 3 series connected Lithium cells or about 9 NiCd

EF-UK Issue 84 - British Electric Flight Association

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