|Oct 04, 2012, 07:52 PM|
Power (systems) for the people!!!
I thought it might be a good idea to feature the systems I have used successfully in several of my aircraft. Power systems can have a huge impact on the performance of an RC aircraft; it is always nice when someone has sort of put all the pieces of the puzzle together, so I thought I'd share mine...
Below are some pictures and specifications of the RC Timer motors I use in my models. I started trying these out two seasons ago - they are similar to the Turnigy gold series, but they have different power ratings and some have different Kv values as well. I suspect that RC Timer sources (or is the source of) these motors out of China.
For models in the 15-19oz. range, I suggest the RCT 1400Kv motor OR the 2200Kv motor. Both offer significant power available over many stock motors on ARF types. (including E-Flites) The 1400Kv has more torque, but the 2200Kv can offer more "power at the prop" for those wanting a bit more aggressive flight envelope. Both weigh in at 50g, and are ideal for the 1lb. class models and are able to deliver in the 80-130W/lb. regime. I run either a MAS 8x6x3 blade, or 8x6 Eflite slowflier prop, or a GP Powerflow type 2-blade with these motors. Running 2S, the 2200 will draw into the 18-22Ap regime, dep. on prop type. The 1400 sits in the 14-16Ap range. Turnigy 30A ESCs are recommended to be certain you have lots of coverage! 2S, 1200mAh batteries can easily deliver over 11-12 minutes of flight time on general cruise, and aggressive aerobatics would run in the 8-10 minutes regime. NICE!
For models in the 26-35oz. range, the RCT 1120Kv and 3S is recommended. I use MAS 9x7x3-blade props, or again a good 9x6, 9x7, or even a 10x7 slow flier prop type like the Powerflow, or E-flite variety. Again, a 30A Turnigy or Eflite ESC are recommended. The 10x7 runs pretty close to the rails on WOT. A 40A may evven be a good idea, though I have never had issues to date.
In the 48-64oz. Category, or for more "scale" mid-70oz. weight ranges, the RCT 900Kv is superb. At 770W, this motor really performs well, and easily drives anything from 11-13 inches without issue. A 60-70A ESC (Eflite 60A Pro on 4S is excellent) or a 70A Turnigy ESC have both shown to handle things very well. Using a MAS 12x6x3-blade on my model 12 Pitts, I can get >70oz. static thrust for unlimited vertical on an almost 4lb. plane. I only run about 40-42Ap on WOT at 4S.
These motors are available on eBay or online at www.rctimer.com
The BC-series are the ones featured here, though a friend got one of the A-series heli motors (900Kv which runs the can stationary) and it was superb as well. The motors are very tough, well made, and VERY affordable! The 1400/2200Kv motors run around US$12 shipped, the 1120Kv is about $13, and the 900Kv about $25-27. But this is easily 1/3 what you'd pay at a LHS for a less powerful motor. An Eflite 450 motor is nowhere near the RCT1120 for the same weight and 1/3 price. It even outdoes a 480-class Eflite also by a bit. The 900Kv sits close to a Power 25 in performance, but at a significant reduction in cost and slightly less weight.
If there's any questions, please feel free to PM me. I'd be happy to help! I hope this information was useful, and will help you all find that sweet spot in a power system to work for your models!
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|Oct 05, 2012, 12:55 PM|
Hi there Wim!
No problem! I am always glad to help. I know many folks have a tough time finding good combinations of power systems to work with their planes, so I thought this blog post might help.
RCTimer is usually around 2 weeks or so - fastest has been 8 days on one order I did last year, slowest was 18 days. (which happened around Easter, so it was probably our Canada Post, not RCT's fault). If you order on eBay, I have seen free shipping or no more than ~$2US to North America. The packages are well packed, so the goodies are well-protected. I'm not sure what motor you're looking at, but I have run several of these in the size/power ranges mentioned, and these are sweet spots for the offerings. Esp. the 1120Kv and 900Kv motors.
What size plane were you considering to use these on? Just curious...
Have a great weekend.
|Oct 06, 2012, 09:18 PM|
Joined Jun 2001
40" span high wing sport model est. 650 grams ready to fly.
Looking for a motor as close to 300 watts as I can find in the 70 gram range.
Will use 3S and around a 10" prop. The B2836-7 looks the best so far.
Can you recommend an Ebay seller ?
|Oct 06, 2012, 11:06 PM|
If you look for a RC Timer motor 1120Kv is the one you want, just enter in the search. RCTimer has an Ebay store also.
The above link should get you to the site - $15 delivered. ($13 plus $2 shipping, same as his eStore).
You'll probably pull close to 300W with a 10" on that motor (mine does 310W on 3S with a 2200 battery). At 650g - you will probably get unlimited vertical on WOT: That plane should haul some serious butt! Run at least a 30-40A ESC. Let me know how you make out! FYI a 9x6 or 9x7x3-blade will also run well on that motor. I have run a 10x7 Powerflow with no problems. Ran about 28.5Ap on 3S with that prop.
|Oct 06, 2012, 11:35 PM|
You'll also find that at cruise, these motors, due to their extra torque (I find the 1120Kv 2836-7 model particularly good for this in its size/weight class) will really begin to "sip" power near 40-50% throttle settings or even lower. When I run my Lancair ES with this motor at cruise (9x7x3-blade MAS) I get around 18 minutes of flight time. When I run 60% throttle, it's still near 12-14, and 75% runs around 9-10. Prop choice will affect this to a degree, as loading of the motor will vary with the prop selection, of course. Even then, I am still only in the 1600mAh range consumed off a 2200 3S.
These numbers are with the 9x7x3-blade MAS prop. A buddy of mine put one of these 2836-7 1120Kv motors on his foam cub (the white ones from Hobby Zone, that weigh in at around 26oz.) in lieu of the brushed system, and put in a 40A ESC (RCTimer unit he had). WOW! This just flew like a crazy bird on fire. Pretty much unlimited vertical with a 2200 in there instead of a 1300 stock battery. I think it was close to 31 oz. AUW with the mods he did to the firewall and such.
He was getting over 15 minutes general flying time with his plane. (with some climbouts, loops etc.).
I think that this motor will be ideal for your plane. Should go very well. Good luck!
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