I did a static run of the new motor with the new ESC and within 3 minutes of running the motor began smoking and the RPM’s began to drastically drop. Another minute or so later and the battery was dead. It went through a newly charged pack in under 5 minutes and by the end the motor was smoking hot, and hot and smoking. I got out my IR thermometer and measured 190\u00c2\u00baF on the motor, just a tad on the high side of things. The heatsink on the new FET measured about 100\u00c2\u00baF and the batteries were about 125\u00c2\u00baF and so were the Tamiya plugs. The only thing that was within a safe operating temp was the newly outfitted FET in the speed controller! Figures, the weakest link in any electrical\/mechanical system is always the first to go. First it was the ESC, so we fixed that, and now it’s the motor. I suppose a veteran airplane guy would say, well duh the prop’s too big and the pitch is too steep. Unfortunately the 10×8 prop is the only one that fits on the stock gearbox without mods. Maybe I need to mod that and try out some different props?<\/p>\n
So in the end, the Graupner 480 BB Race motor isn’t the best choice of motors for the Super Cub, given the same prop, gearbox, batteries, radio and receiver\/ESC unit. The size of the prop is too big and\/or 3:1 gear ratio is too small. Getting the motor to work I think would take a new radio (to stop the glitching), a high-current li-po battery pack (to take the high current draw), and new ESC that can also handle the current, a gear box with a 4:1 or 5:1 gear ratio and props with less pitch and\/or props that are smaller. I’m not sure what it would take to get the exact optimum amount of usable thrust out of this motor for a plane this big. I’m thinking that this motor may actually be better suited towards smaller, lighter planes.<\/p>\n
So I’m putting back in the stock motor. But all is not lost, at least now I’ve got a super beefed-up speed controller that can easily handle a 3S li-po pack with its 11.1V or possibly even a 4S pack for a whopping 14.8V. And I learned a thing or two about putting a new motor into my Super Cub. For now the stock motor should last for a while, and when it finally dies maybe I’ll start looking again for an ideal brushed 480 replacement. Or finally go to a brushless out-runner and be done messing with the power plant in this plane. It might be time to try doing a custom aileron modification. The plane already has plenty of power with the stock motor and the 8-cell pack, I’m sure it’s even better with the 3S li-po. I was able to fly it later tonight, once it stopped raining, and I can still say that this plane is so much fun to fly. I think it flies way better with the stock motor anyway. But it was a bit windy so I did a few loops and brought it back in. It’s pretty cool flying into the wind at 1\/4 throttle and just watching the plane hover in one place. Anyway, back to the drawing board. <\/p>\n
For anyone interested, I ran a simulation of this setup in MotoCalc thought it was pretty funny when they predicted the motor temperature to reach an outrageous 334\u00c2\u00baF during full throttle! They weren’t far off, my motor was well on its way to trying to achieve that temperature. I remember seeing this long before I attempted the motor, but I thought, eh, it’s a simulation, it could be wrong? Well it wasn’t. There’s a pretty cool option called Opinion that spells out in “plane” English (lame pun, I know) how your proposed setup is going to perform (the 100+ graphs they give you just don’t mean much to someone who doesn’t know what he’s looking at, ooh, the pretty blue line goes up and the red one goes down, so is that good or bad?)<\/p>\n
Download the MotoCalc Simulation of the Super Cub with the 480 BB Race Motor. <\/a><\/p>\n Worth noting however is that if we drop the prop from a 10×8 to a 10×6 it appears as though we wouldn’t have the overheating issue and the plane wouldn’t suffer a huge hit on overall performance, although it states that it will be harder to fly and would be more suitable for more experienced pilots. So is that me, yet?<\/p>\n","protected":false},"excerpt":{"rendered":" I did a static run of the new motor with the new ESC and within 3 minutes of running the motor began smoking and the RPM’s began to drastically drop. Another minute or so later and the battery was dead. … Continue reading