Peter_OZ

My Feedback: (1)

Folks,

thoughts on suitable 2 blade prop to go in GT-80 with standard mufflers going into a warbird. I would like RPM around 7500

Idea is to get the engine to unload when it is coming downhill.



thanks
cheers
Peter

STUKA BARRY

I'm swinging a Xoar 24X12 on my Fokker D-VIII 1/3 scale. Dont know exact rpms, but at 32lbs. she moves out. If your warbird is heavy metal, try a 24X12, that should get you moving.

Truckracer

My Feedback: (19)

I always used a Menz or Xoar 24-10 on the GT-80. This is a reasonable compromise between getting the engine to turn in an RPM range it likes and a prop big enough to pull the plane with authority. I doubt the 80 would pull a 24-12 in the RPM range you are looking for. You could go with a smaller diameter, higher pitch prop but then you will lose take off performance and the plane will be much harder to get down to a reasonable landing speed. Go with a larger diameter, less pitch and you lose speed. Its all a great compromise .... especially with this engine that likes to turn high RPMs.

When you say standard mufflers, do you mean the stock mufflers? If so these are extremely restrictive ... you may want to gut them or try something after market.

Now Ralph will probably chime in here about how the 80 will turn a racing prop at such and such RPM and the plane will go 190 MPH ... and he will be correct for his applications. Real world sport planes and warbirds won't perform well with these props though ... even though they will turn up in that high RPM range the GT-80 likes so well. Sorry Ralph, racing props are not for everyone and all applications.

Peter_OZ

My Feedback: (1)

thanks mate, mine is 42lbs

I might get a range of cheaper props to have a play with and see what ground RPMs are like

Pelle Gris

My GT80 on standard mufflers spun a Menz 24x10 2-blade at about 6800 rpm. Getting 7500 rpm on the ground would require either a lighter loading prop, like a Mejzlik or Engel carbonprop, or a smaller diameter or pitch.
Maybe a Menz 22x10 will get you 7500 rpm, but it will be noisy as h***. :-)

Antique

My Feedback: (4)

READ the instructions, 7000 rpm ON THE GROUND works well....
And change the stock mufflers for something less restrictive...
The things I post about racing are to illustrate the strength of the GT80s parts...

Truckracer

My Feedback: (19)

Several years ago, Menz had the Ultra series props .... not sure if they are still available or not. They had rather narrow blades and these props in the 24-10 size turned will into the 7000 range. These props didn't suit all applications but worked well for many.

Rcpilot

My Feedback: (78)

I don't think you can buy an Ultra prop anymore. Maybe, but I ain't been able to find one for a couple years.

Honestly, I would run a GT-80 on a 23-10 prop for break in. Thats a 2-blade that you can get from Mezlik or Xoar. That will get you up into the power band.

Now if you insist on a 3-blade, I'd be running a 22-10. You can get those from Xoar.

Truckracer

My Feedback: (19)

Somehow I can't quite imagine a 23 or 24 inch prop pulling around a 42 pound airplane with any great efficiency. Frankly, I would be looking for a larger engine or at least one that was happy turning a larger diameter prop. The GT-80 is a darn good engine but it is certainly not a great torquer!