Hi Guys,
Wow!!!
This thread has expanded far beyond my original question so I guess I will add a few more comments.
First: In fairness to Mr. Wagner the reason he extended his intake was to project through a profile fuselage so he could choke the engine for hand starting and not to change the engine run characteristics. However, he did say the engine picked up a couple hundred rpm and that is what I quoted.
Years ago I saw a free flight engine with a long intake and I asked a CL speed engine guy about it.
He said that if you want a 2-4 break a short intake like a Fox 35 is best but if you are running a one-speed type of engine run, using a longer intake may help improve the consistency of your needle setting capability. However he also said if you make the intake too long you will lose power just like Randy Smith said.
A 4-stroke engine doesn't have a 2-4 break so a longer intake may not hurt the engine run but it also may not help that much either. I just don't know.
Second: Bob Reeves questioned the validity of flight test results from Mr Wagner bolting a Saito 56 to a Brodak Cardinal & I agree. The 56-62-72 can haul big heavy Strega size planes with no effort at all so using a Cardinal profile for flight tests would yeild somewhat doubtful results. The mental visual of bolting a Tigre 46 to a 1/2A Pinto comes to my mind.
Third: Milton, The results that the RC guru you mentioned was for using an intake stack for a throttled application but when you are using a non-throttled control line stunt application the guru's results may not apply or be true.
The best than can be said is that the result of using an intake stack for stunt is an Uknown and Unproven outcome.
This is comparing apples to unknown oranges without further results so it is at this time a moot point. That is unless you have already done the testing because I just remembered you said you had done a lot of testing with 4-strokes so you may already have test results. If so please share your results.
Anyway,to illustrate my point that 4-stroke stunt setups may suprise you look at Bob Reeves. He used a screw to reduce the intake size and it increased fuel consumption and improved power an engine run which is counter-intuitive to what "should work", but it worked for him.
So Milton, I look forward to your results for using intake stacks on a stunt setup to see what you discover.
Does it use less fuel? Does it effect prop turning power? Does it effect the engine run ? or could you increase the oil content of the fuel to compensate for using less fuel? I am just getting started with a Saito 62 so I would be very curious about your results.
Fourth: I started this thread because I saw the possibility of creating a compact and self contained (meaning attached only to the engine and not the fuselage) way to provide adjustment to the engine run the way Bob Reeves has been doing. In addition I want to adjust it without removing a cowl so an intake extension could be useful to provide easy access.
Yes,I do know that several flyers have acheived good 4-stroke engine runs without using any adjustable feature. However,one of the best features of a pipe-setup is the ability to adjust the engine run for the conditions. So the idea of having more adjustability for my Saito appealed to me. Bob is looking at another way to adjust the run so see his thread on venturi configuration.
I do find Randy Smith's idea of a ram-air-itake intriguing. I wonder if you could make it adjustable?? Humm-mm?
Anyway, Thanks guys this has been a most interesting thread,
Pat Robinson