I have a Tower Hobbies 40 trainer with a .46 engine. I currently have a 10x6 prop on it, which I've had on it since engine break-in (well, not exactly the same one, but the same size anyway )

The vertical performance kind of sucks right now - it slows down pretty quick if I try and do a large loop, even at full throttle.

I've only been flying for 4 months or so, so I'm not familiar with all the variables, but I understand the pitch on the prop has something to do with either speed or thrust?

I think 10x6 is probably at the small end for a .46. If I replace it with a 10x7, 10x8, or 11x5, will I get better thrust and therefore better vertical?

Thanks!

There is a couple of things that will boost your vertical, go to the spad forum and see how to make a mousse can pipe. It was good for 1100 rpm on my OS LA40. The other thing is to try a 11-4, or APC 12.25-3.75 prop. If you are trying to haul a 6 pound trainer straight up, get a WEBRA 50! The other tip is to set your high speed needle with only a couple of ozs in the tank, and with the nose pointed straight up, always, if you quickly pinch the fuel line the engine should not sag, but keep on in a clean scream.

The 12.25X3.75 and a typical .46 will take most .40 size trainers vertical unlimited. On a TT.46 pro... that size prop took my 7.25 lb "TameCat" (discontinued .40 to .60 trainer) vertical unlimited (buzzing the ground to just a dot in the sky) IF I was careful not to lose airspeed in the pull from max speed level flight.

You may run nto ground clearance problems with the 12.25 inch dia prop though... If so, try the 11X5. Yo will see improvement in vertical. But not as much as with the Fun-Fly/3D prop.

Some people will put an 11X6 or 11X7 on a .46.. Yes the 10X6 is a bit on the light side for it. (great for a .40)

I am running an 11x5 on an OS 46AX. And it will will do well vertically. I would not say its totally unlimited on my Avistar, but it will drag it up. And I am running rich. If I had it leaned out, it might be unlimited. An 11x4 works well too. I don't know how much ground clearance you have have but with my Avistar and a larger front landing gear, I am still mowing grass with an #11 prop. I guess you could bend the main gear and extend the front in order to put a 12x4 on it. But I am nose high as it is and can't run a #12 prop.

hey guys, it looks like you want to get more out of those trainers and I don't blame ya. I have a tower hobbies .40 size trainer and it was a blast. It had the tower hobbies .46. The engine is powerful but overall ran crappy. The plane had no problems doing loop after loop. The best thing I have done so far is spend 69.99 bucks on my World models "Skyraider Mach-2", which is a 40 size low wing aerobatic trainer. I put the OS .46AX on there and love it. I also now have a computer radio w/exponenial that makes landing so much easier. This plane has got to be perfect as a 2nd plane. So here is my 2 cents. Quite killing yourself on $4.00 props and running your engines lean and spend 69.99 on a new lighter ARF that will introduce you to a whole bunch more fun. HAPPY FLY'IN

The advice you got is first rate. I only want to clear up something. Remember Pitch=Speed, Length=Power, Get a long low pitch prop and have at it. BTW if you run out of room just get some bigger wheels. Sounds corny but it works.

Mark Shuman

Yep... the William's Brothers 4.5 inch WWI style wheels give little added aerodynamic drag... and an extra inch of ground clearance. (looks wierd to put 3 of these on a trainer...)