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I found that if I gripped the motor shaft with a pair of slip joint pliers a couple of times I could 'knurl' the shaft and make a nice tight fit which the glue would help.
Of course, Pat's solution is best, but, mine works when I'm at the field and only have 5 min epoxy to work with. You are welcome for the Al tube thing. charlie |
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Luke, sorry to hear of your troubles with the pinion gear. I guess that's why I almost exclusively use outrunner motors now. They are just simpler and generally give fewer problems. Unfortunately they and their controllers are more expensive than a brushed geared system, at least in the short run. Prices have come down a lot, though.
The motor in my Super Cub has well over 100 hours flying time on it now, without any problems, and is still going strong. It is harder to find the right outrunner motor that will turn a larger prop, so a geared system definitely has the advantage here, but outrunners with a higher wind and/or the ability to handle more amps are getting lighter, so it's easier to turn a big prop and stay within a reasonable weight with one than in the past. There are lots of good suggestions above as far as how to fix your pinion gear, and I'm almost sure you can get something to work. If you continue to have problems, then you might look into and outrunner motor. AmpAce |
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Well, I'm still having some troubles. Pat, I did as you suggested - I pulled the pinion off with a gear puller, cleaned off the shaft and inside the pinion real well, and soldered that sucker on real nice with Stay-Brite and flux. I cleaned out the solder-flecks from the gear teeth and polished the whole thing up. Then slathered it in grease. Back into the gearbox she goes, and plug in for a test. However, I'm afraid to say, the results were unchanged. A pretty mind-numbing rattling at higher throttle settings.
I took the motor back out of the gearbox and checked the pinion gear. My soldering job was a good one and the pinion was still on solid. So now I guess my problem is probably actually something else. The only thing that hasn't been replaced at this point is the Speed 400 motor itself, and the speed control. The motor seems fine to me but I suppose it's possible it has a bad bearing. I doubt the ESC is the problem. I'm kind of to my wits end on this one. I suppose it won't hurt me to buy another $9 motor and see what difference it makes. Perhaps I really should go to brushless... it's not an issue of money any more, but I just didn't want to be overpowered. I also really like the scale sound of the gearbox. But it does seem to be kind of a pain to maintain. Pat I know you used the same setup I have now for a very long time, but then finally switched. I can't remember what motor you switched to. But you obviously made the Speed 400 arrangement work for you, so I know it's possible. On the other hand, if you really prefer the brushless now that you have it, and if it doesn't turn our sedate Cub into a wild 3-D machine, then maybe that's the best route. What do you think? Amp, how about you, what motor are using? Luke |
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Luke, you may have allready posted this, but what size prop are you using/or want to use? As far as gearbox'es, there are some nice aftermarket, durable, alternatives to MPJ and GWS that will work with a sp-400 brushed motor.
E-flight makes some brushless motors in the 400 class and are a little cheaper than the big names, look for one with a LOW KV http://www.aeromicro.com/Catalog/e-f...kv_4218890.htm OR http://e-foamies.com/store/catalog/p...?products_id=1 The microdans are nice for a light weight set-up, you not hot-rodding, so with a 2-S batt., you could prop up to 11/7 and not overload the motor. Also, what you describe has got to be a out of balance prop, its painted right? Try another thats not painted / re-balance |
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Last edited by mike3976; Oct 15, 2006 at 08:13 AM.
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Luke, In the first 380 flights on my Cub I wore out 2 gearboxes, 1 motor and an ESC. BTW, there is such a thing as the shaft slipping in the armature inside the motor -- had one do that to me once.
Anyhow, the set-up I'm using now is the E-Flight 920 kv Park 400 with an 11-5.5 APC E prop and a Thunderbird 18 ESC with a Thunderpower 2100 2 cell battery. So far, it's going strong at about 80 flights. Also, don't forget about the $29.95 Motor ESC combo from www.rchotdeals.com . Stay with the lower KV and you'll be in good shape. Several of these units are in service around here and are all working great. In fact, that's what I'll be setting my new Super Cub up with. The ONLY downside to the system is that when you first power it up it sounds like the horn in Larry the Cable Guy's pick-up truck! And speaking of the Super Cub, the plans are done, will get the test parts ordered and the plans copied next week. Then it'll be time to build it!!! PAT |
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Luke, on my Super Cub, I'm using a Nippy Black 1812/100 running on 3S lipos with a Phoenix 25 controller. My Super Cub weighs 32 oz. ready to fly, and I suspect your Cub comes in significantly lighter, so this motor might be a bit much. For my Super Cub, it's just right giving performance very similar to one of the higher-powered Super Cubs. It is a light motor, weighing only 2.13 oz, so would be quite a bit lighter than your S-400 setup. You could try it or a similar motor on 2S lipos, and I'm sure it wouldn't be overpowered. I've recently switched from a GWS DD 10 X 5 to a 12 X 5 wood prop, and although the amp draw is a bit more than the motor is rated for, I've had no problems, and the motor/esc come down cool. I'm probably getting away with this because I use full throttle rather sparingly, and then only for short bursts. The 12 X 6 works a little better than the 10 X 5, performance-wise.
By the way, for some reason, that 12 X 6 wood prop makes the most realistic noise. You can hear each prop stroke resonate through the fuselage. It is not noisy at all, but the noise it does make is very cool. I think Pat's suggestion of the RCHotdeals motor/controller would certainly be worth a look. For that price, you could hardly go wrong, since Pat knows of some of these working well in the Albuquerque area. There are no doubt similar other combinations available too. Just look for a low KV and somewhere around 50 to 70 watts per pound, and you should be fine. Pat, The Super Cub drawings look great, but I just have to inquire, what's up with the tandem wheels on the main gear? I think I recall seeing a picture of a Super Cub equipped like this somewhere, but that's really unique for a model! Anyway that is a feature that's easy to modify. I've used several different sizes of wheels on mine. Right now it is using 4 1/2" Trexlers which replicate the 31" Alaska bush wheels. AmpAce |
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Quote:
Thayer |
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Thayer, thanks! I realize by doing this, I'm running some risk of frying the ESC, but actuallly, I'm still within it's spec's. If I recall correctly, the 12 X 6 wood prop on 3S lipos is drawing around 23 amps static. The motor is rated fopr 18 amps continuous, but I can't recall the burst rating for it. I dont know how much this prop is unloading in the air, but it's bound to be a little at least. The guiding criteria I've been depending on is the motor and ESC temp when I land. On several of the setups on other planes that use Axi motors, the motor and ESC come down pretty warm, and they have all performed well for extended lengths of time, so I'm assuming that for this one it should be pretty safe. Probably a bad assumption?
I don't want to add any more weight to the plane, and so far haven't found a motor that is rated to turn the 12" prop, that wouldnt make the plane heavier, even with a 2S lipo pack. I also don't want to go smaller with the battery pack, since the pack costs about the same as the motor, and over drawing the pack is a sure way to ruin it. AmpAce |
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Amp, What's shown is the Whitaker Tandem landing gear arrangement. It uses 2 stock Cub wheels and pivits in the middle. I built one for the 1/4 scale Super Cub many years ago and it's been working great for rough fields. Actually, it will crawl over anything that doesn't hit the prop first. The drawings for making one will be included on the plans, set up for 2" wheels.
PAT |
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Last edited by P. Tritle; Oct 15, 2006 at 12:49 PM.
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I'm not saying it won't work, as many have demonstrated it can, just that you pay your money, and you take your chances. Operating outside the recommended parameters means you are working into whatever unknown overhead the designers included, if any, at an increased risk. I agree that temp is the best guide, and if all is cool, all is probably well.
Perhaps the best reason not to run electric power systems hot is that heat is simply wasted performance and duration. Interestingly, not all e-power setups unload in flight, and some do not unload nearly as much as you might expect. We have even seen some models that have an increase from the static load when flying at full power. I have just finished a review for a 2-meter electric sailplane. It is not a hotliner by any stretch, but my ZLog altimeter clocks it at a bit over 1200 fpm in an extended climb. The Eagle Tree Micro Logger shows that it only unloads about 8 or 9 percent in the air, not nearly as much as some guesses I have heard. Thayer |
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Mike, it's not an unbalanced prop, as I've both balanced the painted one on my Great Planes prop balancer, and I've tried other, unpainted props. So I think I've ruled that out.
Pat, that is an interesting observation about the shaft slipping inside the armature - guess there's no way to figure out if that's the problem without basically destroying the motor. I may just do it to find out. And I'll probably throw another Speed 400 in there just to see what happens - at 9 bucks it can't hurt. Still, the brushless option is sounding nicer, especially the RCHot deals combo. Boy, what a difference in price compared to some of the other setups! It makes me wonder if it's incredibly poor quality, but if others have been using them successfully then I can't argue with that. And it's not like I'm powering the space shuttle or anything. The lowest kV rating I could see on their cheap motors was 1000 kV. They have two versions; the only difference being one has a larger shaft. Do I need a longer shaft given the cowling on the Cub? Short Shaft - 2409-18SS Long Shaft - 2409-18 I just weighed the Cub ready-to-fly, and it comes in at 25 ounces almost exaclty. So a bit lighter than yours, Amp, but still heavier than Pat's prototype (must have been all those rib repairs we had to make ). Converting to brushless we'd probably save an ounce. Either way, the wing loading on this thing is less than most of the gliders I've flown! Can someone tell me what meaningful parameter I should associate kV ratings with? Does lower kV mean higher torque, or lower current draw, or what? I'm used to amps and volts but this new brushless stuff can be confusing - there's number of winds and Y vs Delta and and orangutans and breakfast cereals, and fruit-bats... I just need to spend a couple hours reading over in the motors forum. Luke |
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Lower Kv gives less RPM on the same voltage than a higher Kv. It does not relate directly to power, as that is a function of how many watts the motor can handle without burning up.
Think of Kv more as a gear ratio like in your car transmission. Low Kv, like a low gear, gives lots of pulling power but you won't go too fast. Good for slower draggy models like Cubs, biplanes, gliders, or grandpa's station wagon pulling a trailer up a hill. High Kvs are more appropriate for faster sport models, racers, hot liners, and tooling down the autobahn in something new from Stuttgart. Higher Kv does not mean more power, just more RPM, best suited to smaller props turning fast, rather than big ones going slowly. Thayer |
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