What size prop would be the best?

[Ryan Nau]

I just bought a Hacker B20-18L with the stock gearbox. What prop would be the best for the motor on 8x1300CP batteries?It has the 18jeti esc, so can;t draw over that in amps. I'm going to use it in a Kyosho Ferias.

[RD Blakeslee]

Ryan, problem is, not too many guys will be flying that particular airplane - motor combo.

I've found one of the best (and most fun) parts of getting into eflying was buying and using the MotoCalc program.

It gives you a way to explore the entire flight envelope of your model. Results aren't gospel, but are illuminating and useful.

[KOMET 44]

jube good words of wisedom. Ryan what props do you have rite now?What is the gear ratio?i use 3 tools
Calculator,Astro Watt meter,and a fishing scale.Also what kind of performance do you want? Flight length,or aerobatics? looking at the plane i think its just rud/elev control correct? If i had to guess i'd look at graupner slim prop9x6 these prop are very efficent.good luck,stefanP

[Ryan Nau]

Thanks for the help. I use that E-calc on the www.flydma.com site.
The ferias is a trainer type plane, but I really like flying it and want some more power for it. It is a 4.4:1 gearbox. Yes it is rudder/elevator, no ailerons. I'm looking for areobatics more then flight time. I have a few Graupner 9x6's and 9x5's, so I'll start out with them.

[steve lewin]

With that high a gear ratio I think you're going to want a bigger prop. 10 x 8 or even 11 x 8 looks more like it on Motocalc figures. Even those will draw less than 10A. A 9 x 5 will be nearer 5A, not a lot of power at all.

Steve

[KOMET 44]

Steve i was just guessing off the top of my head.Ryan with that gear box listen to steve's advise.At least a 10"prop.This is why its best to list all the components so others can help more efficently.good luck,stefanP

[vintage1]

12x8 or 13x8 looks like a good staring point according to Motocalc.

Pulling mid to high teens in amps.

[Ryan Nau]

I'll first try a 12x8. I have a bunch of them from my E3D. I still should have a little ground clearance.

[Azarr]

Originally posted by Ryan Nau
I'll first try a 12x8. I have a bunch of them from my E3D. I still should have a little ground clearance.

Ryan,

The gear ratio is actually 4:1, not 4.4:1. With a 12 x 8 you're going to be close to 19A, I'd try something smaller.

Azarr
www.ecubedrc.com