Wasn't getting replies in the Pylon World forum...

So...pasted here...

Just curious on some non-competitive but super fast props for the GMS .47

I was getting 15,000rpms with an APC 11x5 on the ground.
Radared my Advance 40 at 110 level.

Sold the advance and looking to maybe put some speed to the old GMS.

Anyone flying a GMS .47 FAST??? Best prop???

Thanks!
CrazyHerb

Hi Herb,
It looks like you nav'nt had much luck in this forum either so I will try to point you in the right direction. I'm not real familiar with your engine but a good friend of mine who manufactures Ignition set-ups for all large displacement and whose plane he works on and pits for holds the top speed record can probably tell you anything you want to know.
His web page is www.rcignitions.com and his name is Ralph Cunningham. If you contact him at his web page I'm sure he will be a big help to you.

Herb,

All depends on the weight and drag of your airplane. Sometimes you will get more speed with a larger prop of same or less pitch.

Before switching to a Jett FIRE 50 I put quite a few flights on my Diamond Dust with an OS 46FX. Keep in mind it is only a 34" wingspan delta that weighs under 3 lbs but in my case I always went fastest with an APC 9X8 sport prop. I tried an 8X8 and turned more rpm with the same pitch but didn't go any faster because I didn't have enough thrust.

You will just have to experiment depending on the airplane will be flying but I would say with that engine 9 inch props would be a good starting point with smaller airplanes. For bigger planes you might have to take whatever you can get with a 10 inch prop.

Hi,

A good starting point is an APC 9x7

I run this prop on my pylon racers and it is plenty fast. A smaler prop will most likely not have enough "pull" unless you have a light and/or slick airframe

Stefan

Excellent,
Thanks guys...
I'm thinking about a slick little foam core delta..
I'll try one of each and go from there...your help is much appriciated!!

I'll post pics/speeds if I ever get it built...

CrazyHerb