clovus

OK, here goes. A friend returned a favour to me by buying me a ARF plane with BL motor, BL esc and lipo. Very nice of him! Perusing the specs has made me wonder about the power system he chose and exposed a deficiency in my knowledge. I have only ever bought complete combo packages, thinking that the vendor has worked out the correct motor, batt, esc combo.

Now I have a bunch of bits and am unsure if they will provide optimal performance. My mate is a nitro flyer and said the recommended motor looked too small for the plane so he got a bigger one. The operating amps are 22 with a peak of 33. However, the lipo is a 3s with a normal current draw of 15. The esc is OK at 40A.

Would I notice an improvement in performance going to a higher a lipo,l ike a 20c? Is the motor underperforming?

Link to the motor: http://www.peakmodel.com/index.php?m...roducts_id=260
the lipo: http://www.peakmodel.com/index.php?m...products_id=93
and the plane:http://www.peakmodel.com/index.php?m...roducts_id=143

clovus

Fliprob17

It depends on what the capacity of the pack is. Take the mah rating of the pack, say 2100mah for example, divide it by 1000 to get to amps = 2.1 then multiply it by the C rating 15 = 31.5 amps continuous. So say that it also has a C rating of 20 for max. burst, which in this example would be 42 amps. So if you have a 2100mah pack you should be within range. Having an underated LiPo will cause the battery to get overstressed, hot, possibly swell up, and maybe even worse. With a motor pulling that many amps, you may need to look at a 20C battery. It depends on the capacity of the pack. If the LiPo is underated, you are not going to get to the full potential of the motor if your power source can not deliver adequate power/current.

Fliprob17

I just looked at the link to your batter, it is 2200mah, 15C continuous and 20C max. which would be 33 amps and 44 amps, respectively. So you should be well within the range of the motor. Just check the heat of the battery after some test flights.

clovus

Wow!
Thanks for such a quick reply! All this stuff is a learning experience. The more I can learn the better! Can't wait to build this one, the control surfaces look like they' ll have a FAIR bit of movement in them. Should be a good 3d ship, or at least something to throw around the sky.

clovus

clovus

Another question,

Whats the difference between an outrunner and a inrunner BL motor?

clovus

Fliprob17

The inrunners typical require a gearbox because they have a much higher rpm/kv rating. So you need the gearbox to slow them down, so you can throw a bigger prop on. The outrunners typically run lower rpm/kv ratings, therefore no gearbox required. They both mount differently as well. The outrunner typically is a stick mount, while the inrunners sit in more of a carrier so to speak.

Fliprob17

Also, the outrunners seem to have a higher power/weight ratio.

Herugrim

If the speed 400 Cap232 is the plane for this set up, you are running 240 continuous to 360 peak watts in a 21 ounce empty, say 2 pounds AUW plane; you are at 120 to 180 watts per pound. More power than i could manage properly;that is Very overpowered.

Fliprob17

Clovus, watts = volts x amps

A 3S LiPo will vary from 9.9 volts (low charge) to 12.6 volts (full charge), so for these examples I picked somewhere in the middle. Your plane will most likely be a little under 2 lbs, but that is the number that herugrim threw out there, so that is what we will use.

watts = 11.1 (mid. charge) x 22 amp continuous motor rating = 244 total watts / 32 oz (2lb) plane with everything in it = 122 watts per lb

watts = 11.1 (mid. charge) x 33 amp max. burst motor rating = 366 total watts / 32 oz (2lb) plane with everything in it = 183 watts per lb

For high performance and advanced aerobatics you need 110-130 watts per pound
For light 3D you need 130-150 watts per pound
For Unlimited performance you need 150-200+ watts per pound

So, with the estimated spec's above, you will have high performance/aerobatics avail. at a contiuous rating at all times, somewhere around 65%-75% throttle and be able to do 3D manuevers with a little more throttle. In my opinion, you will not be overpowered.

clovus

Thanks for running the numbers for me. 122-183 watts sounds OK. I thinkit should be quite nice with that, and I agree with you fliprob17, I feel it would be quite managable with good flight performance, and not too out there in the power stakes.

clovus

Fliprob17

Ya, I think it will really haul when you want it to [:-] , but will fly nice and steady when you want it to as well.

packyj

I too am building a peak model plane... with weather starting to turn south on me I'm kind of taking my time with it, they suggested to me the a22-20l for the extra 330L

pretty sure it will fly about the same with a little less peak amps, plane has gone together pretty well so far, had a broken wing out of the box which was replaced free of charge and very very quickly. Customer service seems to be above and beyond what i've dealt with even here in the states with the bigger companies.

clovus

Mine is in the queue, I've got two planes ahead of it. Please post a report as to how you like it (might hurry me up!!).

clovus