How to dial in proper speed/load on a BL motor?

[slikrx]

I picked up 2 feigao brushless motors t o see which works better as a DD tail for my Frankencompychopper.

http://liteflyrc.com/Feigao%20motors/1/pic.htm

5200 kV motor, 5 amp max

and

http://liteflyrc.com/Feigao%20motors/0/pic.htm

4200 kV motor, 4 amp max

I also picked up an assortment of small (1 inch - 3.5 inch) propellers.

After some hassels getting the tail ESC to arm (thanks for the help making it easier, Gino!) I got one of them spun up. (don't know which motor, but using the propeller recommended by bladecprepair.com)

It got HOT (140+ - too hot to touch) after a couple minutes (less than 3) of spinning it up.

I know you don't want to run a motor with too little load or it will over rev, and I know you don't want to overload it either.

My question, is how do you "optimize" your prop size & pitch & duty cycle to make sure you're getting the most out of it, without hurting it?

[slikrx]

Also, my selection of props is:
part # size
EP 5030 5.0 x 3.0
EP 4530 4.5 x 3.0
EP 4025 4.0 x 2.5
EP 2510 2.5 x 1.0
EP 0330 3.0 x 3.0
EP 0320 3.0 x 2.0

(and I think 1 or 2 are reverse pitch)

Some of these have small shaft holes (1 or 1.5 mm), soI'll need to tweek them as well... :badair:

[smw]

I am not sure if this will help but I am running the same Feigao 5300 KV motor on a small delta wing (Stingray). I am using a 3020 prop on it with a 7.4 V Lipo. It also gets a bit warm but it is not excessive. Throttle is generally wide open.

[slikrx]

Definitely good to know!

My heli runs an 11.1V 3S Lipo, but this is for the tail motor, so it will (in theory) only see WOT on occasion.

Wait, this means your is running as a pusher? are you running ClockWise or CCW? (as looked at from the motor output shaft side)

I know they are intended as ducted fan replacements, but that doesn't help me much :oops: :dontknow

[txflyer]

i use the 3020 prop with my dd tail. the motor doesnt even really get warm. maybe alittle. i have i think 5 to 7 packs with that setup and not one problem.. i dont know if that will help with a brushless motor or not..also i use a 11.1v 3s pack and once the heli leaves the ground it doesnt touch it till the pack is done for.

[smw]

Wait, this means your is running as a pusher? are you running ClockWise or CCW? (as looked at from the motor output shaft side)

I know they are intended as ducted fan replacements, but that doesn't help me much :oops: :dontknow

Here's a picture. It's running as a pusher. It uses a wobbly prop adapter. I'm not sure how relevant this setup is to your tail drive, but it is run WOT most of the time (unless I am walking over to pick it up :D ).

[slikrx]

That pic is a big help, actually. I have to verify for sure, but I think I was spinning my motor in the opposite direction (without doing any timing changes) so that in and of itself could be a large part of the heat issue.

I'm thinking that if I run the correct direction :shock: , and run a slightly smaller )and lower mass) prop, but at the least, a 3020 should be fine... :thumbsup2:

Thanks guys!

[Skiddz]

See if you can mount the motor so T/R thrust blows back over the motor (tractor config vs. pusher config) which will help keep it cool. Also, a heatsink will help as well.

[Buzzkill]

Slikrx: I just tried this with that setup.

http://www.helifreak.com/viewtopic.php?t=35208

[slikrx]

See if you can mount the motor so T/R thrust blows back over the motor (tractor config vs. pusher config) which will help keep it cool. Also, a heatsink will help as well.
I was running it in tractor mode...

I hadn't put the heatsink on, but given how quickly it got hot and how hot it got, I'm not sure how usefult it would be...

I see in Buzzkill's pictures that he is running in pusher mode and isn't having troubles. AND he's running the large prop. (which I thought was part of my problem)

My concern is that themotor is designed to run as a pusher, and the timing might be wrong to spin in the other direction. I know I can reverse the ESC direction and change the timing (to some degree) so I may try that in tractor mode before I remount the tail for pusher...

:bomb: too many options! :(

[Buzzkill]

Slikrx: I tried the 3020 prop last night and had really good results. Less throw inhard manuevers. Less mass, so the motor spins at higher RPM so I dont know how your heat issue will be afected but I did a couple packs this morning outside and my tail motor was warm but not hot. Anyway, I think I'm switching to the 3020 seems to work better.

[slikrx]

sa-WEET!

That's kinda what I was hoping for.

I brought my heli to work so I can swap tail mounts and tweak a couple things, so with luck I'll be ready for a shakedown this weekend.