Stuka Stunt Main Forum · 9 of 9 known posts recovered
Dont worry about the mule going blind 'til you get the cart loaded!
Methinks it was merely a goof in typing 52.
Leonard Neumann
No... two different animals.
Doug was flying the OS 52 Surpass in the Blue and Red Bear (never was much of plane until the OS came along). The Bear is 58 oz and 650 squares with the 4 cycle installed.
Doug and I are liking what we are seeing. We are both pursuing something at 4 pitch and below. The RPMs are above 10,500 for just about everything we are trying. Basically, our venturis are at near WOT. Doug was burning 3.5 oz of 20/20 fuel.
Doug has an OS 26 Surpass on his P-force. Results are mixed, as this was a car motor converted over to airplane.
IN a nutshell, the tank arrangement is the same. The venturis are much bigger and the RPM's much higher than I published in my first Saito article. We are now finding the peak of the HP curve very quickly and the speed just "sits there" much better. It also appears that at the higher RPM's it is more important to have the engine somewhat under loaded, so it is allowed to "freewheel". Since the engine is finding the back side of the HP curve all by itself, there is no need to control the speed with load.
These are at least my first impressions. I am apprehensive to say we have it figured out BUT IMHO Doug's OS 52 was performing at near the top 1% of motor runs. It was indeed, at first glance, pipe like without the pipe. Very cool.
The City Smasher
Leonard Neumann
Alan
OS 26 is correct. Sorry.
The City Smasher
About the 26 car motor. Yes Len the motor is supposed to turn 17500 rpms in a car config., read that alot less drag and only 10-12% oil NO CASTOR fuel. It is made differently in the valve train with copper inserts in the bowls and springs designed for that rpm range. They also have a 40 setup the very same way. As far as timing goes I think it is pretty much the same. Once I got a prop on it it ran rpms comparible to the standard 26. The power feels to be the same and so on. But it seems to use more fuel. The cool thing is it likes the car tuned pipe. The pipe gives it a minor boost in power and big jump in RPM compared to just standard exhaust. Also the exhaust pipe is larger than on the standard 26. The conversion was just the crankshafts. The rest was left alone. The valve train is deffenently stronger. You can put on a 7" prop and it will go 15500 on the tach and no clatter or any strange noises. Just singing along so happy. I think the timing is not much of an issue since there is no real ignition. I think I need to replace the ring on the car motor, if it has one I cant remember. When I break it down I will measure the cycliders and see how much difference there is.
Also I have mine on a Venturi setup. The motor has a carb mount right on the head. I removed the carb and had John Grigsby at UHP turn down an FP 25 ventrui on the insert side until it slipped right in. I use the small OS 25FP NVA. Runs very smooth in this config..
Doug Moon
Dont worry about the mule going blind 'til you get the cart loaded!