March The EFO Officers 2011
Contents
1. http www allerc com hyperion eos sentry battery checker p 5701 html Rick Sawicki looks over Ken s An 2 tail model Ken Myers shared the progress on his An 2 He d never used planking for compound curves on fuselages and thought it was a good idea to once again practice the technique that he learned from Jim Young on RC Groups March 2011 the Ampeer Page 7 The Scale Builder s Workshop Video Tips July 2005 Planking Compound Curves http www rcgroups com forums showthread php t 395721 Ken also showed the video Jim is also an EFO member Jim has a lot of great tips and videos on RC Groups but you have to search carefully to find them A good search term to start with is Scale Builders Workshop Ken noted that he s not very good at the technique and has planned on changing the planking from 1 16 to 3 32 balsa since the sheeting got too thin on his model Ken also shared a very funny video about when the beginner shows up at the flying field to learn how to fly using his 100 mph ducted fan It is well worth the watch especially if you ve ever been an instructor http www youtube com watch v hx5Es0bnulM Ken also showed his new Scorpion S 4035 250 4963 250 465g that he purchased for the An 2 from AirCraft World in Japan since there were none available here in the US It came from Japan in six days with a shipping cost of only 6 88 http aircraft world com The meeting continued w2. necessary and second 2 digits are the case length in mm This is a somewhat common practice by some suppliers although other suppliers may add a dash between the first 2 digits and second 2 digits Other suppliers use the stator diameter and length in mm in a similar fashion From now on I will be using the exterior dimension 4 digit number a dash and then the given Kv followed by the weight in grams in the Ampeer so that motors can be compared directly More on motor naming conventions can be found here http homepage mac com kmyersefo e basics e basics htm MOTORS EFO Meeting WEDNESDAY March 9 The March meeting will once again be on a WEDNESDAY March 9 It will be at Ken Myers s house starting at 7 30 Everyone with an interest is welcome See you then Modern Power for a 48 Lazy Bee From Brian Amato Traverse City MI via email Hi Ken I had lost contact with you and The Ampeer glad to have it back Since you ve been so good about answering questions in the past here s one for you A guy named Andy Clancy designed and sold a light big winged model airplane he called the Lazy Bee I have one but haven t flown it yet Back when I built mine the only thing going was a big ol heavy geared motor and Nicad battery packs weighing a zillion ounces Since then there have been huge advances in motors props and especially batteries My questions to you are 1 Do you know any guys flying a 48 s
3. www gobrushless com shop index php app c cp0 amp ns catshow amp ref scorpion S2 30mm Castle Creations Thunderbird 36 Brushless ESC http www toddsmodels com Castle_Creations_Th underbird_36_Brushless_ESC_p tb36 htm Hyperion G3 CX 2100mAh 3S 25C 45C March 2011 the Ampeer Page 4 http www allerc com hyperion g3 cx 2100 mah 3s 11 1v 25c 45c lipoly pack p 4512 html Drive Calculator http www drivecalc de indicates the following Aeronaut E prop 9 5x6 10 69v 19 1 amps 204 5 watts in 9269 RPM APC 10x5E 10 66v 20 7 amps 220 3 watts in 9032 RPM Next I went to RC Groups to see what I could find on the Lazy Bee I actually wrote my reply before reading the following which appears in the Scorpion motor thread on RC Groups http www rcgroups com forums showpost php p 14893811 amp postcount 6643 You ll find the original post about halfway down the page This is from the Scorpion motor thread on RC Groups Quote Originally Posted by phillipduran I recently purchased a Scorpion SII 3008 1090KV motor and I m wondering what ESC and battery I should go with I m in about week two of learning electric power systems and I m still wandering through the woods The plane it s going on should end up around 40oz and has a 48 wingspan I m going to stick with Scorpion for the ESC and after a bit of research I m thinking a 35 amp ESC is what I need Could I get away with a 25 amp The plane is a Clancy Lazy Bee so gentle easy
4. flying is what the plane is made for As for batteries I don t have a clue so any suggestions would be appreciated Flight times of at least 10 minutes would be fine with me If that means I could go with a lighter battery and save weight which would be great Answer from Lucien Miller of Innov8tive Designs I think this motor might be a lot of power for this plane buts its built to handle up to a 20 size gasser so it s still going to end up lighter than it would with a glow power system Whenever you select an ESC for a motor you should choose one that is at least equal to the highest current that the motor is rated for even if you do not intend on running that much current The Scorpion SII 3008 1090 motor has a max current draw of 26 amps so I would go with the next standard size ESC available which is the 35 amp model One thing that people forget to take into account is the surge current that you get every time you advance the throttle Even though a motor may only pull 26 amps at full throttle you will see currents of 30 or 35 amps for brief periods of time every time you goose the throttle This is because the motor needs extra current to speed up but once it gets to the new higher RPM the current drops back down to the steady state value That is why it is a very good idea to have an ESC that is one size larger than you really need to be able to handle the current surges that you end up seeing That partic
5. I also got the plans and the original magazine I plan to convert it to electric but have not started it yet it is one of several items waiting for my attention in the workshop I am looking forward to future articles to see how you make out with your version Take care John Jackson Russell Ontario Some Good Advice on Trimming From Frank Gue via email Hi Ken I appreciate your sending me this material Always something good I find that some perhaps many of our electric flyers have little or no free flight background Mine goes back to 1942 when I was Junior Champ in Edmonton Alberta with rubber power in the likes of the Korda Wakefield I have been designing and building models ever since and hold patents as I may have told you When designing you must know the fundamentals of stability when flying you must know the fundamentals of trim and the difference between stability and trim Most chaps fly ARFs these days More than once I have watched a frustrated ARF flyer trying desperately to correct a stalling or diving aircraft without knowing what he was doing or perhaps relying on one of the several incorrect myths about trim With a new design I always test glide in high grass before applying power If it is a really radical design let s say a canard I may build a model of the model maybe one quarter size from 1 16 sheet as a glider to get the CG position right Cont on
6. ck series amp parallel pack at 70ish amps Figuring 75g per cell a 14 cell pack would weigh about 1050g or 37 oz For a 14S pack my Kv spreadsheet suggested a Kv of 146 at 40 amps when using an APC 20x13E prop The suggested Kv is plus or minus 10 so that would mean from about 130Kv to 160Kv A check of Scorpion motors shows its largest motor with a Kv that low It is the Scorpion S 5545 150 6589 150 1022g That is a bit heavy for our purposes http www gobrushless com shop index php app ccp0 amp ns catshow amp ref SC55 The Scorpion S 5535 160 6539 160 811g might work http www gobrushless com shop index php app ccp0 amp ns catshow amp ref SC55 Drive Calculator does not have an APC 20x13E prop in its database but Scorpion Calc does http www innov8tivedesigns com P10 Scorpion Calc predicts that an APC 19x12E would yield the 35ish amps Also Drive Calculator predicts that an APC 20x10 would yield the approximately 35 amps These are the numbers we are looking for For a 7S2P at 70ish amps my Kv spreadsheet suggests a Kv of 307 using an APC 20x13E It looks like a Kv of about 300 would work for 20 inch props with this battery The Scorpion S 4035 330 4963 330 442g is close to the suggested 300Kv http www gobrushless com shop index php app ccp0 amp ns catshow amp ref scorpion40 Scorpion Calc suggests that with this pack and the APC 20x13E the amp draw would be 70ish Drive Calculator also
7. eadsheet that I created I was verifying my numbers using the April 2011 Fly RC magazine When I took a preliminary look at the motor data for the ElectriFly Tiger Moth on p 77 I found the numbers didn t jive at all with what I was predicting for the Kv of an appropriate motor using a Great Planes 8x6 Power Flow Slo Flyer Electric Prop which the author noted only as an 8x6 slowfly prop When I noticed the reported RPM of 4450 it made me wonder I looked up the data for the Rimfire 250 outrunner and found it to weigh 20g and have a Kv of 1750 http www electrifly com motors gpmg4505 html When I learned that the motor has a reported Kv of 1750 I really began to wonder what was going on My spreadsheet was predicting a much lower number The author Jack Tracey noted the following motor ESC prop data RimFire 250 outrunner exterior dimensions1 Kv amp wt 2813 1750 20g 8 amp brushless ESC and 8x6 slowfly prop Full Throttle power 8 3 amps 48 watts in 96 watts in per lb 48 watts in 8 3 amps 5 78 volts into the ESC Vin 4 450 RPM 1750 Kv 2 54 volts out Vo The ratio of 2 54 Vo 5 78 Vin 0 44 The formula shows that only 44 of applied voltage to the ESC is turning the prop That is very poor but It is very hard to create a small mass 20g outrunner that is very efficient especially when trying to turn a relatively large diameter p
8. ic wing loading is 10 5 4 Prop could be 20 max diameter I would like a Scorpion motor maybe 55xx xxx using 12s1p A123 batteries if possible I could charge with my Xtrema as 6s2p at 6500mAh 3 6v max and 3 3 nominal and reconnect to 12s1p when flying I would use a CC ICE HV 60 amp ESC with a separate Rx servo battery A target draw of 35 amps would be ideal Weight wise it looks like a draw when swapping out glow to electric fuel not included Thanks for your help Cheers Rich Hi Rich The two significant numbers are 14 pounds and a maximum prop diameter of 20 inches This is a sport plane which defines its mission As you noted it already has a wing cube loading of 10 5 oz cu ft That puts it into the Advanced Sport Plane category with wing cube loadings between 10 oz cu ft and 13 oz cu ft To figure the power loading and since you think the weight will be a wash then 1400 watts in would be appropriate for a power loading of 100 watts in per pound Using my sweet spot of 35 amps for A123 2300mAh cells that would be 14 cells or about 100 watts in per cell 1400 watts in suggests an outrunner motor weight of between 1400 watts in 3g of motor weight per watt in or 467g to 1400 watts in 1 75g of motor weight per watt in or 800g Using 14 A123 2300mAh cells provides two possible ways to achieve 1400 watts in It can either be a 14S series pack at 35ish amps or a 7S2P pa
9. iews posted Good News DSM starts hopping HORIZON CATCHES UP http www rcmodelreviews com You can learn more about this at http www horizonhobby com DSMX I m wondering if the X in DSMX stands for 10 Anyone know I had predicted this would happen for a long time Thanks to Bob Aberle and Warren Plohr for keeping me in the loop on this one Thanks for the February Ampeer From John Jackson via email Hi Ken Thanks for the newsletter great as always I enjoyed this issue more than usual for two reasons My first plane was a Leisure Playboy I can still remember how the other club members treated it as a Novelty and were offering condolences to my instructor for being stuck with the electric guy and having to make it fly Well it did fly but not that fast compared to the other gas planes of the day I recall one day where the head wind pretty much matched my maximum speed which made the plane stationary with respect to the runway Someone scrawled No Parking on the lid of a pizza box and stuck it on my pilot station Interestingly some of those hecklers now fancy themselves as 3D electric pilots Their selective memory prevents them from recalling the No Parking incident from twenty years ago The second item of interest is the AN 2 article A member of a nearby club passed away a while back and his widow held an estate sale I bought a framed up AN 2 built from Don Luck s set of plans
10. is correct As it turns out using the RimFire 300 exterior dimensions Kv amp wt 2822 1380 27g might be a better power system choice It weighs 7g more than the RimFire 250 and has a Kv of 1380 I used Drive Calculator DC and found two motors similar in weight and Kv to the RimFire 300 They are the Pulso X 2204 54 exterior dimensions Kv amp wt 2824 1375 27g and the AXI 2204 54 exterior dimensions Kv amp wt 2823 1400 26g DC shows that when used with an APC 8x4E prop and a 300mAh Li Poly these types of motors should pull a little less than 5 5 amps spin the prop at about 6600 RPM and have a drive efficiency of about 66 6600 RPM 1380Kv 4 78 Vo and if 6 75 is used for the input voltage 4 78Vo 6 75 Vin 0 71 or 71 of the voltage in is used to turn the prop at 6600 RPM That is a much better number and probably the best that can be achieved using this diameter prop with this small of an outrunner The motor ESC and battery at less than a 5 5 amp draw are all in a much safer range and the power out is actually the same or slightly better than using the RimFire 250 and the 8x6 slowfly prop but with an almost 1 3 reduction of amp draw The RimFire 250 outrunner with its 1750Kv would be better used in an application where an APC 7x4 sport prop could be used when using a 2S 300mAh Li Poly 1 Exterior dimensions first 2 digits are the diameter in mm rounded to the nearest mm if
11. ith refreshments and electric plane talk It was a very nice evening An 2 Progress from the Middle of January to the Middle of February By Ken Myers I continued to rework the plans based on the top wing area model I created I reread Keith s article about building on the half shell and crutch The technique appears in Building and Flying Electric Sport Scale article This is a great builder s resource It is available in four linked Acrobat pdf files on the EFO Web site The downloads are found here http homepage mac com kmyersefo sitetoc html The Scorpion S 4035 250 arrived on January 22 and I used it to input the motor dimensions into my 2 D CAD program I started working on the drawings for the built up vertical stabilizer and rudder I once again reread Keith s article and decided that a crutch build was not going to work so I switched to the half shell method I spent quite a bit of time on the Internet trying to find a solution to the tail wheel rudder linking I decided that a control line elevator control horn should be used for the elevator I continued working on the horizontal stabilizer design I thought that I might have a problem with the angled h stab and rudder line and the rudder area that is in the vertical stabilizer I made a Foamboard model to check that it would be okay It worked fine On January 29 I had a major problem CADintosh crashed and would not let me do a
12. last page March 2011 the Ampeer Page 10 The Ampeer Ken Myers 1911 Bradshaw Ct Commerce Twp MI 48390 http homepage mac com kmyersefo The Next Monthly Meeting Date Wednesday March 9 2011 Time 7 30 p m Place Ken Myers s House see above kmyersefo mac com or 248 669 8124 Some Good Advice on Trimming cont With a proven design an ARF one should go through the procedure in the user manual or else the free flighter s procedure to get CG right and trim right If you want a few hundred words article on this much of which would start right out with the above give me a shout Word count and deadline Cheers Frank Gue Burlington ON Look for Frank s helpful information on this topic in an upcoming Ampeer KM Upcoming E vents March 9 Wednesday EFO monthly meeting at Ken Myers s house 7 30 p m Everyone with an interest is welcome April 1 3 57th Weak Signals Toledo RC Expo info at http www toledoshow com Don t Miss it June 4 amp 5 10th Annual Keith Shaw Birthday Party Fly in near Coldwater MI see this issue for more details July 9 amp 10 Mid America Electric Flies Midwest RC Society 7 Mile Rd Flying field Salem Township MI CDs Keith Shaw and Ken Myers Presented by the Ann Arbor Falcons Electric Flyers Only of Southeastern Michigan and the Midwest RC Society Info Contact Ken Myers
13. nymore drawing I spent a frustrating amount of time installing a newer version of the program It also changed all my CADintosh files to the newer version so I am stuck with it even though the problems continue including not being able to print tiles of the plan to tape together for the full size plans I continued to work on the whole tail area design with many many revisions I thought that I could use the double sided control arm from a DuBro tail wheel assembly for tail wheel and rudder hook up I found that the scale position for the rudder control was going to work okay as the servos would be located above the windows Rick Sawicki visited and brought a good selection of control line elevator control horns for me choose from and a Klett tail wheel assembly I decided to print the tail plans and build a model of the fuselage tail using Jim Young s planking video to learn the technique http www rcgroups com forums showthread php t 395721 That is when I found out that the program was NOT printing tiles correctly It took four days of working on and off to learn the tail planking technique I changed the plans as necessary when I found errors On February 6 Keith called and we talked about the progress on the Ant and he gave me some March 2011 the Ampeer Page 8 invaluable guidance on the control system rudder tail wheel hookup I found an article that showed how to hook up a T
14. pan Lazy Bee and if so what are they using successfully as a motor prop battery combination 2 If not can you tell by looking at the specs what would make a good lightweight combo for this aircraft March 2011 the Ampeer Page 3 Mine is the extended wing version and it will NOT be flown on floats at least for now http clancyaviation globalhobby com lazybee htm Thanks in advance Brian Amato Traverse City MI Hi Brian Yes I remember the Lazy Bee well The first thing I did was to check to see what kind of ground clearance it has I remembered it being a bit squat I found the plans on RC Groups http www rcgroups com forums showpost php p 10476900 amp postcount 12 I then imported an image of the front of the plans into my CAD program and drew just the essential lines and scaled them to determine the prop diameter Front with scaling completed Scaling showing a ground to center of motor shaft clearance of 5 763 inches Without repositioning the motor it looks like you can get by with a 10 diameter prop if you have pavement exceptionally short grass bare ground to take off from or if you use a hand launch A 9 5 diameter prop should give enough ground clearance for normal grass flying field takeoffs The plane s mission is to fly around gently as a floater With 638 sq in of wing area and a wing cube loading WCL of between 3 oz cu ft to 5 oz cu ft the ready to fly RTF weigh
15. rop I wondered why Great Planes Tower Hobbies had recommended the prop they did since it over amps the ESC probably the motor and the recommend battery March 2011 the Ampeer Page 2 The power system is running very inefficiently at even less than 50 of the input power I checked the Tower Hobbies Web site and discovered that the recommended prop is the smallest Slo Flyer prop that Great Planes distributes Ah You cannot argue with success though It works with this plane according to the author In the Airborne section of the review the author notes It floats around at a gentle speed at about 1 4 throttle This indicates that it has more than enough power for its intended mission If I was going to use the same motor and ESC as used in the review and I saw the numbers presented in the article on my power meter the first thing I would have done would have been to try an APC 8x4E prop It draws less current than a slowfly 8x6 and in this case actually increases the power out An APC 8x3 8SF would not be a good choice as it would not decrease the current as much as the APC 8x4E The SF or slowfly type props are current hogs but useful in some applications In the caption of the picture showing the mounting of the motor on p 77 Jack notes The RimFire 250 is the best choice for the model It fits the cowl perfectly If fitting the cowl perfectly defines best choice then maybe that
16. suggests that an APC 20x10E is about 70ish amps Both of these systems should give the desired watts in of approximately 1400 while swinging 20 inch diameter props The 7S2P system with the S 4035 330 might work okay but it has a few drawbacks While the motor is rated for 2400 watts in a 65 amp maximum continuous amp draw is recommended so it would be pressing the motor a bit hard This was also noted by its lighter than minimum 467g weight Also it would require an ESC rated at 70 amps 1 25 inverse of 80 or an ESC rated for 87 5 amps or more A Castle Creations Phoenix ICE 100 http www castlecreations com products phoenix_ice html NOT the Lite or the Phoenix 80 http www castlecreations com products phoenix 80 html might be good choices The weight of the motor and battery pack would be about 1500g or 53 oz That is close to the weight of your S T 3000 engine system This setup would change the weight the least The 14S1P system with the Scorpion S 5535 160 will probably be a better solution It is slightly more efficient because it is a higher voltage and March 2011 the Ampeer Page 6 lower amps type system The motor is rated for 3600 watts in with an 85 amp maximum continuous amp draw recommended You would be under utilizing this system a lot It would require a high voltage ESC rated at 35 amps 1 25 inverse of 80 or about 43 75 amps or better A Castle Creations Phoenix HV ICE 60 http
17. t would be between 28 oz and 46 5 oz My guess is that it will come out right in the middle of that range or pretty close to 37 25 oz It certainly doesn t need more than 70 to 80 watts in per pound That means that about 175 watts in would be a good target If you use a 3S Li Poly then 175 watts in 11 1v about 15 75 amps The speed control should be 15 75 amps 1 25 the inverse of 80 which is about 20 amps The Li Poly can be a 3S 1500mAh type The motor should weigh between 175 watts in 3 watts per gram or 58g to 175 watts in 1 75 watts per gram or 100 g You really want to go with a motor that is at the heavier end of the weight range for balance reasons The original had a pretty hefty hunk of iron there The motor Kv using an Aeronaut 9 5x6 Electric Flight Prop http www hobby lobby com 9 5x6_electric_flight_prop_fiberglass_white_768_prd1 htm should be about 1050 If you go with an APC 10x5E prop then the motor Kv should be about 950 I would do it just a bit differently from those numbers even though the watts in would be more than necessary This design needs weight in the nose I would go with a heavy end motor and use the ubiquitous 3S 2100mAh 2200mAh Li Poly pack An outrunner motor will be mounted further forward than the old ferrite motor and I d get the pack as far forward as possible A setup that I would personally use Scorpion SII 3008 1090 95g 3834 1090 95g http
18. tail on a glider and I ll be using the method for the Ant tail I ran into a pretty big oops on the plans I realized that I had not reconciled the top and side views which came from different 3 views This took a lot of time to correct Shows tail strut wing struts and hinges During my Internet research I had found some photos of plastic models of the An 2 They showed the parts I used the tail strut detail to get the correct shape for it I made a tif of the tail strut that could be under laid in the CAD program drew it and size if for this model Image used in CAD program I will be pressing on even though my CADintosh program is still not printing tiles correctly and I m in constant contact with the developers which is eating up a lot of time Right now it is time to get an order into Tower Hobbies for the ICE HV 60 ESC and other items while they have free shipping Made my 369 order on Feb 16 arrived Feb 18 Free shipping Don Belfort s Nesmith Cougar Progress Update From Don Belfort via email Hi Ken The Nesmith Cougar is coming along We were out flying in 4F on Saturday morning 1 22 11 It made Sunday s 15F temperature seem warm March 2011 the Ampeer Page 9 Toledo is getting closer Don Spektrum Starts Hopping By Ken Myers Every morning I go through my email inboxes RC Groups and RC Model Reviews On the morning of Feb 3 I noticed that RC Model Rev
19. the March The EFO Officers 2011 President Vice President Secretary Treasurer Ken Myers Richard Utkan Rick Sawicki 1911 Bradshaw Ct 240 Cabinet 5089 Ledgewood Ct W Commerce Twp MI 48390 Milford MI 48381 Commerce Twp MI 48382 Phone 248 669 8124 Phone 248 685 1705 Phone 248 685 7056 Board of Director Board of Director Ampeer Editor David Stacer Arthur Deane Ken Myers 16575 Brookland Blvd 21690 Bedford Dr 1911 Bradshaw Ct Northville MI 48167 Northville MI 48167 Walled Lake MI 48390 Phone 248 924 2324 Phone 248 348 2058 Phone 248 669 8124 Ampeer subscriptions are The Next Meeting 15 a year US amp Canada Date Wednesday March 9 2011 Time 7 30 p m and 20 a year worldwide Place Ken Myers s house see address above What s In This Issue Do You Ever Think About What You Read Modern Power for a 48 Lazy Bee E Power for a 1 4 scale Spacewalker February EFO Meeting An 2 Progress Belfort s Nesmith Cougar Progress Spektrum Starts Hopping Thanks for the February Ampeer Some Good Advice on Trimming Upcoming E vents Do You Ever Think About What You Read By Ken Myers Well do you Last night at the February EFO meeting Arthur Deane asked a question about why the Kv was an important number I answered it somewhat but wanted to do a better job so I spent the morning playing with Kv While working with a spr
20. ular motor works very well with an APC 10x5 on 3 cells You will get around 40 ounces of thrust with a current draw of 20 amps at full throttle This is more than enough power for a Lazy Bee aircraft Most of the time you will find yourself flying at half throttle where you will only be pulling 9 10 amps of current If you run a 3 cell 2200mah battery this is only a 4 to 5C discharge rate and will give 12 15 minutes of flying time per charge at reduced throttle and 5 6 minutes of flying time at full throttle all the time If you want to save a little weight a 1500 or 1800mah battery can also be used with slightly shorter run times Lazy Bees are a popular topic on RC Groups Here is a link to one of the Bee threads http www rcgroups com forums showthread php t 1174275 I hope this information gets your Bee in the air this spring Ken E Power for a 1 4 scale Spacewalker Rich Sievert Midwest RC Society via email Hi Ken Would you please give me advice on converting my 1 4 scale Spacewalker from glow to electric The current model specifications are 1 1 4 scale 14 lbs RTF less fuel 24 oz tank built in 1994 2 S T 3000 engine 54 oz with muffler pump mount and tank Flies best with 18x8 14 prop 6300 RPM The kit recommends engines 90 1 20 2 stroke or 1 20 1 60 4 stroke March 2011 the Ampeer Page 5 3 Wing span is 84 wing area is 1110 sq wing loading is 29 06 oz sq and the cub
21. www castlecreations com products phoenix_ice_hv html or the Phoenix HV 45 http www castlecreations com products phoenix_hv_series html would be good candidates The weight of the motor and battery pack would be about 1850g or 65 oz That is heavier than the weight of your S T 3000 engine system by 11 ounces I don t believe that would make a huge difference The wing cube loading would go from 10 5 oz cu ft to 11 oz cu ft The power loading using the APC 19x12E at approximately 1425 watts in would still be about 97 watts in per pound Right now there is a shortage of Scorpion airplane motors here in the US I ordered my Scorpion S 4035 250 for my An 2 from Air Craft World in Japan http aircraft world com It arrived 6 days from when I ordered it and the shipping cost was a remarkably low 6 88 Hope this helps and I can t wait to see it fly Ken The February EFO Meeting The weather was okay for the March EFO meeting and it was held at Ken Myers house on February 9 as planned Roger Wilfong brought along several items to share He showed a mini catapult glider from Retro RC Roger is also into model rocketry and plans to power another version with a tiny rocket motor http www retro rc net home html He demonstrated the use of his Hyperion EOS Sentry Battery Checker He even showed how to measure the voltage of the popular single Li Poly cell used for indoor flight This is a very useful tool
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