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Model Forum / Radio Controlled / Air Models / March 2007ESC's for brushed need quick info.
Need to know what sized ESC I need for a 540 and 600 brushed motor, got the chance of a couple of 25A but not sure if they will do, anybody give me a quuick answer?, regards, Terry > Need to know what sized ESC I need for a 540 and 600 brushed motor, got > the chance of a couple of 25A but not sure if they will do, anybody give > me a quuick answer?, > > regards, Terry 25A is good. Only buggy motors and a few cobalts can draw more in that class. I tend to use 3s LIPO and prop for about 20A. The message <1175115275.16355.1@proxy01.news.clara.net> from The Natural Philosopher <a@b.c> contains these words: > 25A is good. Only buggy motors and a few cobalts can draw more in that > class. > I tend to use 3s LIPO and prop for about 20A. Thanks for that, have a chance of two at about $9 each so may grab them and even if they cook it isnt that great a financial loss....;-) regards, Terry > The message <1175115275.16355.1@proxy01.news.clara.net> > from The Natural Philosopher <a@b.c> contains these words: [quoted text clipped - 8 lines] > > regards, Terry Gear them though. The DD prop on 3s LIPO is impossibly small I've got a couple in 3.6:1 drives running 11x7 props that haul a pair of 5ft old timers around in a bumblingly antique sort of way. Run at about 16A. ALL day and forever. Barely ticking over. Need the noseweight ;) Opened up they haul these sub 3lb models up at a fair clip. Or cruise around for 40 minutes on half throttle. | Gear them though. Absolutely. | The DD prop on 3s LIPO is impossibly small A 2s LiPo would probably work better for direct drive, since these motors are generally designed for 6 cell NiCd packs. Yes, they're more efficient at 3s, but then you need to shrink the prop so much that it's only really appropriate for a pylon racer. In any event, there's a large number of planes out there, usually gliders, with direct drive speed 540 and 600 motors in them, and 6-7 cell NiCd sub-C car packs. They generally perform poorly, because the motor has too high of a Kv rating and so they have to use a little prop and so performance suffers. To improve performance, they use a slightly bigger prop, but then they're pushing the motor and batteries too hard and neither lasts long. Adding a gearbox allows you to use a larger prop (so the pitch speed is closer to the cruising speed of the plane) and more cells in your battery pack and not push the motor so hard, so everything works better. Of course, gearboxes are often expensive, and tend to be hard to find room for. Often you can buy a low Kv brushless motor for about the same amount of money as a gearbox will cost you.  SignatureDoug McLaren, dougmc@frenzied.us `Some guy hit my fender the other day, and I said unto him "Be fruitful and multiply". But not in those words ...' -Woody Allen > | Gear them though. > [quoted text clipped - 23 lines] > room for. Often you can buy a low Kv brushless motor for about the > same amount of money as a gearbox will cost you. You can indeed. I tend to use gearboxes more because the outrunners will not reliably deliver power at very low RPM. For flying scale subjects with scale diameter propellors, its seldom more than 3000 RPM. The message <1175184323.3074.2@damia.uk.clara.net> from The Natural Philosopher <a@b.c> contains these words: > You can indeed. I tend to use gearboxes more because the outrunners will > not reliably deliver power at very low RPM. For flying scale subjects > with scale diameter propellors, its seldom more than 3000 RPM. If I can find suitable gear sets for the job I can build my own boxes from PCB board and polycarbonate sheet, small sub-miniature bearings are easy to find on eBay and I have a couple of dozen 3mm bore in my box for later on when I have a play with building my own motors but they are just as usable for gearboxes and much cheaper than buying ready built boxes. I recently found a set of plans for Tupolev Tu095/142 Bear on eBay for pennies printed on three sheets/ five sides and on the sixth side unknown to me was a nice plan for the Global Flyer, problem is the G.F has such a slim fuse it would need to have the motors set well back with long shafts so I have been looking at a way around it by constructing a long very lightweight alloy frame with one double ended motor in the centre and long shafts in bronze bearings driving both props then wrap a fuselage around it, little engineering jobs like that interest me as I have the workshop for it, regards, Terry > The message <1175184323.3074.2@damia.uk.clara.net> > from The Natural Philosopher <a@b.c> contains these words: [quoted text clipped - 20 lines] > > regards, Terry You are a lucky man.. |
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