Motor for Trex 500 with 5 blade head

[EnstromPilot]

I am starting to get all of my parts to build a scale AH-6 Little Bird out of my Trex 500 ESP. I've seen several builds where people have changed out the motors on their helis to accommodate the lower head speeds of a five blade system. The popular motor seems to be the Scorpion 3026 -1210KV and a 12 tooth pinion. So, I ordered one from gobrushless.com, and received a message saying that there was an inventory error, and they didn't actually have any. Instead, they have offered me 2 Scorpion 3026-1000KV motors for the price I paid ($109) or a full refund. Is this a good deal? Will it run the 5 blade head fine or should go with another motor?

[goodhunting]

Do your math....
RPM = Kv x Volts x 0.9 x pinion tooth count / main gear tooth count

Thus will give you 100% RPM at the end of the flight...
Depending on the ESC you want to set up around 90%... so count that in the equatuon.

I don't have a 5 blade head but would figure that you want around 1300 RPM (someone please correct me if I'm off here) and go from there...

Gh

[Andy01]

I would think that 1300rpm for a 5 blade 500 size might be a bit low - better for a 5 blade 600 size.

I would suggest around 1600rpm as a starting point for a 5 blade 500, and try to get lower. I run my 2x 465mm UH-1N at 1700rpm, and it flies well.

RPM = 1000 x 22.2 x 0.9 x 12T / 162T = 1480rpm at 100%, so a bit low, but a 14T would give you 1726rpm at 100%, so governing to 1600rpm would be running the ESC at 93%, which is fine.

I would say get the 1000kV motor.

This assumes you have a 500 with a 162T main gear and straight cut Mod 0.6 pinion.

Colin

[EnstromPilot]

Thanks for the formula and the help! This is my first heli in which I haven't used the stock power system, so the calculation is new to me. I went ahead and got the 1000kv and a 14T pinion. Can't wait to get my Little Bird up and flying!

[JonU]

I'm having a hard time finding any of these motors for my Trex 500 scale project. Any body have an "in stock" source for motors in the 1000kv-1210kv range?
-Jon

[TACO88]

This is what I have on my UH-1 project installed on a Trex 500. It seems to be a good motor and does the job just right. Spinning 480mm Zeal blades with a 13T pinion.

http://www.savoxusa.com/Savox_BSM375...m3750p1200.htm

[JonU]

Thanks Taco88!! Looks like a pretty nice motor and the price isn't as bad as a Scorpion (IF they still made what I'm looking for).

How about the 4050 version below? I can't imagine that for scale, the additional $60 would be worth it.

http://www.savoxusa.com/Savox_BSM405...m4050p1200.htm

[TACO88]

I checked the specs of both motors and they have similar specs ,continuous 1800 watts, Current 99 amps and 1200kv. The cheaper BSM3750 should do just fine.