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Build log: Redwing RC 76" MXS-R STOJANOVSKI SCHEME

Decal Dennis

Decal Dennis

TEAM EP&G
Well I do have 6s 5300mah packs for my Trex 700E FBL that I run in series, but those have 200 amp bullet connectors, my 6s 4000mah packs for my other heli's have deans, which I was planning on using deans in this plane. So I guess I'm trying to say...at this point in time, I can use the 4000mah packs.

I'll get you a weight on the plane, may have to go buy a scale tho.

If you guys think I really need to buy a different motor, I can do that, but will just put this plane on the back burner for awhile til I sell enough graphics to pay for it lol
 
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Aeroplayin

Aeroplayin

70cc twin V2
GYRO said:
He was talking about using two 6s4000 in parallel.

When I built the MXSR with a DLE30, it was about 11.4 lbs or so, and had heavy servos. I figure an electric setup wouldn't have less than 11lb AUW.

Btw, for reference this flight is on 6s5000, Motrofly 4330-400, 11lb AUW plane.
Click to expand...

Then this is fine, but the batteries are going to be a little stressed with a 20x10 on a 400 Kv. The best way to tell is the Amps and the RPMs because Watts is really not telling the power story at the prop shaft. If you are getting less than 110A and the RPMs are less than 6760, then you're sagging to less than 3.6 volts per cell at WOT, or the 400Kv is off a bit.

Anyway, at 400Kv and 3.6 volts per cell, the 20x10 should deliver 110A, and about 17.5 pounds of thrust in a pull-out. At 110A, the 4000mAh batteries will last about 5 minutes the way I fly, which is a 34C discharge rate. This may look more like 2390 Watts than 2600 Watts.

If you are getting 105A, then the voltage is down to about 3.52 volts per cell. This also means about 6610 RPMs, only 16.9 pounds, and a little more flight time. When I say "only" I'm being subjective, of course, but it is only 1.5-to-1 thrust to weight. I was getting almost 21 pounds of thrust from the 21x8 with the DM4330-206Kv on 2x 6S 3300's. and only 70A.

On my 10.8 pound Edge 540, I went with the A60-8S on 12S with the 21x10 Falcon, and some silly power. Now that I went to 12S, I can't imagine going any other way on planes this size. Just me, but the power is there if I want it, and when I don't, I just need to remember that the throttle is the stick on the left, and I don't have to push it as hard anymore unless I want to. :)
 
Decal Dennis

Decal Dennis

TEAM EP&G
I am at a point where I can power up what I got up with a 20x10 or 18x6 prop, hook up the watts up meter and see what I get.

Should I or would I be wasting my time?
 
Aeroplayin

Aeroplayin

70cc twin V2
I would try what I have first. If I had a 270Kv motor and 2x 4S batteries for an 8S configuration, then I would expect a 20x10 Xoar PJN to do 6510 RPMs on 3.7 volts per cell, which is about 72A and 16.5 pounds of thrust. With a 4000mAh capacity, I would expect at least 7 minutes of flight time. The pull out power is on the light side at 1.5-to-1 thrust to weight, but the pitch speed should be nice for big sky aerobatics. The 18x6 will be very disappointing on 8S, tho.
 
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Decal Dennis

Decal Dennis

TEAM EP&G
For sheets and giggles, I will test what I got and give you the data for analysis. Also the weight of the plane. Then hopefully we can come up with a good setup.

Again, I appreciate your help.
 
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