Originally Posted by
airraptor
That is true but you need to match the right prop to the engine and airframe. If you come in to a forum asking for help then to take the advice given to you then do come and ask for help.
Again as three peopl have said that isnt the right prop for that engine and airframe. From what you stated in here it doesnt seem you dont know how to set up pipes for planes either. I am not trying to be mean to you but only help you.
Really? Clearly ALL 3 are wrong. I tried the 9x6 last weekend. It was in the air for about 2 minutes before I landed and took that thing off and tossed it. I knew my static test stand numbers were decent. That 9x6 didn't work on my club40 pylon racers and they damn sure don't work on this thing! Especially with the conditions we have been experiencing here in FL lately. With a 9x6 the thing is an absolute pig. Slow and the motor never pulls down in the turns nor will it gain rpm on a down line. In fact, it sounds like a boat that is cavitating the prop or like a race car with a slipping clutch. It never grabs the air and goes. It just cavitates, or so it sounds.
Put the 8.8 x 9.0 and everyone at the field agrees and can see plainly, it's MUCH faster, unloads nicely and the motor sounds (and runs) much better.
Yeah you're right.... what do I know about tuned pipes. Pressure waves, Port Timing, Expansion chambers, scavenging, port velocities and the like.... My little .40 was already turning a 9.0 pitch prop at 16,000 static before all the naysayers about my prop selection. Now I have tweaked on the motor more, hand worked the prop, changed the carb (other carb was having issues) and now it turns just over 16,500 with the 8.8 x 9.0. I am interested to see how many of you have a TT Pro .40 that is STOCK and club40 legal (sans pipe), turning 16,500 with a 9.0" prop on the bench. Seems to me that is one stout little engine.
I came on here asking about anything I should know about the maiden on the airplane, not whether or not my prop selection suited anyone else. And honestly, any respectable engine guru will tell you that without knowing the specifics of someones set-up, their elevation, atmospheric conditions, fuel, engine details and a myriad of other factors, to just throw out a blanket "That's not the right prop" is simply absurd.
The 9x6 is a pig on my ship. 3 people suggested it, why doesn't it run right? Oh I remember, I put a pylon prop on and thought it was a pylon plane!
Oh and to the reply about static thrust... ah.... well your calculator is off. I have the digital scale on my test bench that says it absolutely does. I test all my pylon planes. Pitch absolutely changes the thrust because changing pitch changes the numbers on that scale. And you are right, thrust is great for hovering, but we are talking high speed plane right? I am not interested in thrust at 8000rpm. I used the prop that creates the most thrust at the rpm where the engine runs the best, which seems to be around 16,000 or so. What was that prop you ask...? The 8.8 x 9.0 APC. That is why it's on the airplane. Of the 60 props I have for a .40/.46 did you really think I just randomly pulled that one out, without any idea of what it was capable of (or what I was doing) and stuck it on the there and yelled "Pylon Prop.... Pylon Plane.... Yeeeeee Haaaaaa"?