4-stroke

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Go with the Saito. If you, for some unknown reason, are still concerned about "reliability", add Perry pump(s)

I don't have any experience with the pumped O.S. four-stroke, but I do have several Saitos and one O.S. Surpass II. I'd say the pump is something that could REDUCE reliability....

I would not hesitate to fly a twin powered by two Saitos (or non-pumped O.S. four-strokes).

Good flying, desmobob

I would definitely add the Perry fuel pump on the Saitos. I have flown three of the Saitos and with the Perry pump, they are really solid. They do take a little time to break in, so I would run them for a couple of tanks on the ground or fly them in another plane for a bit before the first flight.

Bob

Thanks everyone.

I believe I will go with the OS pump.

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The Senior Pattern Association's most competitive and permitted engine is the OS FS-91 Surpass II/P (pump) engine. The fellows using them claim that they are the best powerplant for powering their planes (30% nitro fuel too!). These fellows are older modelers, on the average, and many are ex pattern pilots. If anyone is critical of an engine, it is pattern pilots, ex or otherwise.

I just bought two of them from Tower myself for SPA usage.

Ed Cregger

messagenews: snipped-for-privacy@corp.supernews.com...

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I am just repeating what I have been told. The claim is that throttling is significantly enhanced and the extra nitro lets them pull larger than normal props, although I wouldn't swear to it.

I did buy a case of 30% heli fuel just to try it for myself, after break-in, of course.

Ed Cregger

Ok,

I sorta agree with using 15% max.

So, 14x6 at 9400. I guess a 14x6 3-blade would get 9000.

So 4 os 91 pumps with 14x6 3 blade, 15% nitro 18% oil - common fuel.

I'll keep this group informed on building progress of the Don Smith B-24. Almost got the tail group complete.

PowerMaster fuel (18% caster/sysnthetic, 15% nitro is quite common in my neck of the woods). I don't think you can get 9000 rpm for a three bladed 14x6 prop and unless you're after looks why would you? If you need more static thrust you could try a 15x4 wide APC prop instead. I think a three bladed 14x6 prop will bring the rpm way down for the engine to be as effective as it needs to run in the 9000 rpm range.

Ed - please post your findings once you've taken data with the 30% nitro fuel that you have.

Yah,

I agree. I will do a static test on the right props.

Just thinking a three blade would look nice!!!! Actually 4 - 3 blades

I will be post>> Ok,