Duane-RCU

My Feedback: (5)

I have a used Webra .40 (Speed .40 I think) with an Ultra-Thrust muffler. What prop would this like? I guess it will also want around 10% fuel?

Julian537

My Feedback: (9)

What plane are you putting the motor on?
Warbird or large airframe= 10x5-6
predator= 8.5x7.5 or 9x6-7

combatpigg

My Feedback: (3)

The old wooden RevUp 8.5x6.5 pylon props worked good. They had light high aspect blades. You can find carbon props of similar size and shape.

Duane-RCU

My Feedback: (5)

I just stuck it on the Rookie .40, with the TT .40Pro it went 103mph. If it won't go any faster with the U/T muffler than the .40Pro stock can pull it, the engine is for sale (again)
What rpm do these engines like? And is it going to turn more than the TT can? I stuck a 9x6 MA Simitar on it for now, might try a 10x5 APC too. I was just in a mood to do some motor swapping this weekend, took the .25 off the Q25 back-up Viper, stuck the TT .40 on the Viper (going to try to make some of the 424 races in Sept) Rookie got the Webra. Still have some other options to play with, MVVS .77, a Rossi Pylon .40, among lots of other stuff I don't seem to be putting to good use.

Julian537

My Feedback: (9)

If that Webra is on the rookie, try a 9x6 or 9x7. Not sure if 8x7 will have enough disk area for the rookie? the rookie has a pretty draggy airframe and thick wing cord.
What prop were you using on the TTpro on the rookie?

Duane-RCU

My Feedback: (5)

The 9x6 Simitar went around 16,500, a MA 10x6 went around 15,500, the 9x6 seemed pretty good, but I didn't have a 10x5 or 9x7 handy today. The TT on the Rookie was a 10x6 MA. The throttle pushrod started binding, cutting todays testing short. The Viper was going really good in 424 trim!

combatpigg

My Feedback: (3)

Any .36 to .40 sized "performance" engine in a well matched airframe should be propped to turn at least 18,000 rpm with a 6 pitch prop. That will get the plane barely into triple digits.