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Model Forum / Radio Controlled / Air Models / June 2004Speed-400 overheating and venting
I have a NSP Sandy electro-glider with S400-6V on 8-cell Sanyo-600AE with 3.8:1 planetary gearbox and aeronaut 11x7 folder. I installed the gearbox very recently but I am disappointed with low current draw. The above setup draws only 5A, while the same motor direct drive on 7-cells and 6x3 folder, drew 9A. I am suspecting that maybe I have overheated it at the end of last season and killed the magnets, because I do not have cooling vents. Would overheated magnets lower the current that much? What is the best size of intake and outflow fuselage vents for S400 motor? This glider has a small fiberglass fuselage. Are NACA intake scoops much more aerodynamic than round holes in the nose? Is NACA scoop worth doing if I won't build a duct underneath? I want to be careful choosing the vents as not to introduce too much drag. On another note, if I get a new S400-6V, will I get 7-8A with the above setup? What are good S400/480 motors with adjustable timing, 2.3mm shaft (for my gearbox) and which would work well for the above setup? How do I pull the pinion gear from the old motor? Thank You, Michal  Signatureu*x sys admin, programmer, aviation enthusiast, photographer Can't help you with the motor specifics, but GWS makes a nfty little pinion pulling tool for about 12 bucks. Carried by many eflight retailers. PCPhill > How do I pull the pinion gear from the old motor? > > Thank You, > > Michal Try http://www.hobby-lobby.com for all your speed 400 needs. A little airscoop is not going to change the aerodynamics of a regular electric glider. If you want cheap, use plastic spoons for intake and exhaust. You can buy a pinion puller but you may as well get a new pinion gear for U$5. And yes, a S400 6v with 3.8 gear and a 11x7 'should' draw around 9 amps. High heat tends to demagnetize the motor magnets and kill the efficiency. A new S400 is only U$10 or go for a Long Can 400 for U$16. Fritz > I have a NSP Sandy electro-glider with S400-6V on 8-cell Sanyo-600AE > with 3.8:1 planetary gearbox and aeronaut 11x7 folder. [quoted text clipped - 27 lines] > -- > u*x sys admin, programmer, aviation enthusiast, photographer -- 'Fritz the Cat' Blackburn VP-94 Techrep NAS New Orleans http://www.fritzthecat.info > Try > http://www.hobby-lobby.com [quoted text clipped - 7 lines] > High heat tends to demagnetize the motor magnets and kill the efficiency. A > new S400 is only U$10 or go for a Long Can 400 for U$16. I went ahead with the upgrade. The Rocket 400 motor has a plastic end-bell, so I was able to advance the timing. Unfortunately due to a softer steel can, I stripped the mounting threads. No problem, some 5min. epoxy to hold the mounting bolts solved that problem. On a fresh 8 cell Sanyo 600AE this motor with an Aeronaut 11x7 folder and 3.8:1 gearbox drew exactly 13.6A. Both EPEC and Motocalc predicted this value, so I'm happpy. For cooling vents, I made a triangular opening in the nose above the motor and three round exit holes at the bottom rear of the pod. Thrust is _waaaay_ up and it should easily climb at 45deg angle. I'll post flight results soon. Also the lighter trick to remove the pinion worked great. Thanks for everybodys input, Michal Signatureu*x sys admin, programmer, aviation enthusiast, photographer >>Try >>http://www.hobby-lobby.com [quoted text clipped - 23 lines] > > Thanks for everybodys input, You might care to try that motor on 3s LIPO power and down the prop to a draw similar or slightly lower current level (10-11A). Tentative theory predicts that it should net you about 25% more power out for the same heating. and probably slightly less all up weight, if you pick the right cells (suggest 3s 1800 Irate/Tanics) If you do, I'd be interested to hear any results. > Michal > I have a NSP Sandy electro-glider with S400-6V on 8-cell Sanyo-600AE > with 3.8:1 planetary gearbox and aeronaut 11x7 folder. [quoted text clipped - 6 lines] > > Would overheated magnets lower the current that much? No. Overheated magnets tends to increase current draw massively. > What is the best size of intake and outflow fuselage vents for S400 > motor? This glider has a small fiberglass fuselage. Are NACA intake [quoted text clipped - 4 lines] > On another note, if I get a new S400-6V, will I get 7-8A with the above > setup? Hmm. 3.8:1 and a 11x7? 7A seems somewhere about right. 5A seems lowish. Maybe you have a reverse timed motor..or a 7.2v motor... > What are good S400/480 motors with adjustable timing, 2.3mm shaft (for my > gearbox) and which would work well for the above setup? IF you get yourself a pack of 3s LIPO cells, it will totally transform the setup you have - should pull 8-9A at less weight and give you serious climb. 3s etech or Irate or Tanic 1100 cells will be good. If you sling in a long can 480, and go to 3s2p LIPO cells, you will have a 15A plus draw, and a climb rate that will have you drooling. > How do I pull the pinion gear from the old motor? Not sure. GWS pinion puller? Or maybe its got a set screw? heating brass pinion with small flame (cigarette lighter) should expand it off as well. > Thank You, > > Michal >> Would overheated magnets lower the current that much? >> > No. Overheated magnets tends to increase current draw massively. What about worn commutator? Wouldn't that decrease the current? >> On another note, if I get a new S400-6V, will I get 7-8A with the above >> setup? [quoted text clipped - 3 lines] > 7A seems somewhere about right. 5A seems lowish. Maybe you have a > reverse timed motor..or a 7.2v motor... I'm sure I have a 400-6v. The case says rs-380ph (which should be a 6v variant), and the motor drew correct current when I ran it new direct drive. > IF you get yourself a pack of 3s LIPO cells, it will totally transform > the setup you have - should pull 8-9A at less weight and give you > serious climb. 3s etech or Irate or Tanic 1100 cells will be good. > > If you sling in a long can 480, and go to 3s2p LIPO cells, you will have > a 15A plus draw, and a climb rate that will have you drooling. Unfortunately I don't have a LiPo charger, the packs are expensive and I already have Kan1050 cells for a new pack. I'm considering the Rocket400 4.8-6V motor that Hobby-Lobby sells. It has adjustable timing and should draw 13.5A from my setup. Hobby-Lobby suggests 14A, so it should be OK. Anyways, Could you suggest an air intake hole and diameter? thanks, Michal Signatureu*x sys admin, programmer, aviation enthusiast, photographer |
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