Stuka Stunt Main Forum · 14 of 14 known posts recovered
When the character of a man is not clear to you, look at his friends.
Japanese Proverb
First of all, my engine doesn't say FSR on it anywhere. I'm basing the engine designation/type on a thread here in SSW that showed a photo of what I've got. Dual BB, etc. The experts called it an FSR. It is definitely pre-FP.
This engine makes some serious power for it's size. Mine is mounted in a SuperClown. Way more power than the plane needs. If I optimized it one way, it might make a great non-scale, no-class-to-race-in racer. Best detuning to match the S-Clown so far is to run extra head gaskets and 25-30% oil. (If you want to know the total shim height I'll have to check my notes tonight.) I'd also have to check to see what the OS venturi ID is; .262 sticks in my head. I'm using an OS needle valve assembly, which I believe is .135 diameter. I've been using 10% nitro because that's what the LHS had. It might be a lot smarter to start with 5%. I've been using an OS 762 stock muffler. I've tried regular vented tanks and uniflow. Regular seemed to work as good, and didn't have siphoning issues. I have consistently used muffler pressure with the fuel system. Last trip to the field I tried a Bruline air filter with the dual intent of restricting the venturi a bit and getting clean air in the bargain. I'm flying from an asphalt surface.
I'm still trying to get the fuel system sorted out again after a flameout trying to learn overhead eights. The fuel consumption of this setup is highly dependent on my initial setting. I might get eight minutes on a 3 oz. tank with the takeoff rpm's a little fast. Unfortunately, it can run out at 6 minutes if you set it a little rich -- but with enough power to "try out" a few manuevers. Hence, my bonehead. Before my last "incident," the engine was nearly tamed! Fast 4-stroke with a soft break. On my wish list is a tachometer, so I can perhaps gain some consistency....
I have run with wood (Zinger?) 9-5's, Master Airscrew 9-6 and 9-5's. I recently bought a Brodak BY&O 10-4 to try out. Hoping it will retain the line tension and slow the plane down a little. Haven't tried an APC 9-4 yet. Every time I ask, they are back-ordered. Not really anxious to start propping one of those anyway....
Let me know if there is any specific info you think would be helpful.
Dave
LA_Flyer
I guess I will have to hunt up some shims. I will be starting with 5% nitro, and see how it goes. Got a bunch of 9 and 10 inch props in the 4-5 pitch range. Even a cut down undercamber eather 3 blade, 3 3/4 pitch, that has worked on a couple Webras.
When the character of a man is not clear to you, look at his friends.
Japanese Proverb
I would certainly try the "let it scream" approach if you have a 10-4 or 10-3(?) prop to test. I simply haven't gotten that far. Trying to make one run slow and break predictably might always be second best. I haven't gotten far enough to know that. The one thing that I definitely lost with the "run fast" method is an engine rpm change that warns of pending fuel exhaustion. Since I've dinged mine twice now because of that, maybe that is affecting my approach....
I'll try to get the venturi and head shim measurements tonight. Although I am using an unmodified OS venturi, I wouldn't say that I am using the stock venturi, because this engine came with an RC carb. As has been pointed out many times by the SSW experts, even OS may not know what was standard on some engines....
Let me know how your setup works out. I can use the help!
Dave
LA_Flyer
PS-The engine you have wouldn't be the George Aldrich engine, would it? I really wanted another .25FSR to back up the one I have.
When the character of a man is not clear to you, look at his friends.
Japanese Proverb
Leonard Neumann
I confirmed last night by measurement that I have a .262" ID OS venturi in my .25FSR. After getting some input from Leonard previously, I was going to try to effectively reduce this by using the air cleaner. I don't have any conclusions there yet because something is wrong with my tank from my last "incident." Guess I'll have to open up the tank to figure it out. The first half runs just fine. I suspect that the pickup tube is bent away from the corner. The plane nearly quits, then alternately surges and idles for MANY laps. My first attempt to pop off the front of the tank was not sucessful....
I could not immediately put my hands on the total shim set thickness. It had one shim in it when I received it. (This was a crashed RC garage sale engine.) I know I added one or more that I made from ???? material. I'll keep looking....
Dave
LA_Flyer
Wow! Awesome website, thanks. Yep, that proves that what I have is an OS .25FSR. I didn't realize they came as -S or control line engines. Wish they posted specs for venturi size....
That FSR is gonna make your Streak really haul. If you decide to use a tamer motor, let me know. I'm looking for a backup for my .25FSR.
As far as time warps, I had no idea that the engine was that old! 1977!!! And since you mentioned Harleys, I found an early reference to a Steve Wittman homebuilt aircraft called the Hardly Ableson, powered by, I assume a thumping twin? Fits right in with Fox .35 nostalgia and vibration....
Dave
LA_Flyer
What he said in response was, 'You're taking a fourteen thousand dollar motorcycle, to make a two thousand dollar airplane.
Also, speed on your airplane is going to be determined by rpm and pitch. Prop it accordingly and it will not be any faster than anything else. Just because a Mack truck has a lot of power, doesn't mean it will move down the highway faster than your VW. It all depends on the gearing and the throttle.
Now, as to the homebuilt airplane, where do you get one of these for $2000? Even the price of components, much less the price of kits for even the least expensive of airplanes has gone through the roof.
Leonard Neumann
This was a few years ago.. and it was just a passing comment. But an airplane with a Harley engine, would you want to fly in one?
Well, a HD engine in a plane would probably either make what you got gray, or make the gray that you've got fall out....
Having purchased an NIB Lycoming O-320 for about $20k, buying a Harley for $14k and "throwing away" the bike wouldn't be out of the question, except that there aren't any really good airplane engines except for airplane engines...!
I can't see any reason to even try the v-twin due to the high vibration levels. And reliability.... It would be interesting to know just which engine Steve used. Remember, back then builders even thought that a cast iron Model A engine was workable. I'm amazed every time I look at my Dad's old Ford tractor with that same engine....
Didn't have time to find the shim records last night. Sorry.
Dave
LA_Flyer
You are catching on, a plane like this wouldn't be worth much, oh maybe about $2,000.