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Tri prop for OS FS70

Old 09-22-2003, 03:04 PM
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Default Tri prop for OS FS70

I am putting a OS 70 FS in a 40 size plane and i want it to look scale so i want to run a 3 bladed prop,its going in a Kyosho P-40,what size propeller should i run?
Thanks!
Old 09-22-2003, 04:45 PM
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Default RE: Tri prop for OS FS70

The OS manual says 11x7.

Andrew
Old 09-23-2003, 10:15 AM
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Default RE: Tri prop for OS FS70

What Andrew said.

Another point, any prop that will allow the engine to turn between 9,500 RPM and 10,500 RPM and fly your model the way you want is a "correct" propeller.

You may find that the best flying is with a 2-blade prop because you'll be better able to locate the proper pitch/diameter combination. That's OK. Most scale fliers use a 2-blade prop for flying and then attach a more scale-like propeller for display and judging. With the very limited number of 3-blade props available, it's not easy to get a 3-blade propeller that give you a good match between power, looks, and flight performance. The reason O.S. states that a 3-blade 11 x 7 prop can be used is because the engine will turn it at a reasonable RPM. That doesn't mean it's the right propeller for your airplane/engine combination.
Old 12-06-2003, 11:36 AM
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Default RE: Tri prop for OS FS70

I've just put a new FS70 into an LT-40 to break it in. I'm currently running a 12x7 APC.

When I switch this plane to skis, I'm going to lose some ground clearance. The LHS has a 10x6 4 blade. Would this be OK?
Old 12-08-2003, 10:50 AM
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Default RE: Tri prop for OS FS70

Again, you have to check the static RPM of the engine. If it's turning in the high 9,000's to low 10,000's, then the prop's not too much for the engine. A 6-inch pitch may not be enough at the RPM the engine turns, but the only way to find out is to try it. It may just turn out to be OK, especially since the 7-incy pitch prop you currently have is working all right.

The main thing is that the engine needs to run in its "favorite" RPM range to operate effectively and give you the best output.
Old 12-08-2003, 11:01 AM
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Default RE: Tri prop for OS FS70

For reference everyone.....

I ended up buying an APC 11x6 4-blade prop.... My FS70 turns it at over 11,000rpm on the ground...
A fellow club member suggested that the engine was revving a bit high and that I might need a bigger prop... fortunately, in this plane I don't really need full throttle...
I wasn't able to tach my 12x7 as my H9 DVT is unreliable, I borrowed a Glow Bee to get the reading on the 11x6 4 blader...
Old 12-08-2003, 04:18 PM
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Default RE: Tri prop for OS FS70

Tony,

11K isn't quite too much RPM for the FS-70 Surpass, but it's getting close. If your model flies well with the prop, and you don't spend a lot of time at full throttle, then there's no reason why you can't use that prop. Just limit the max RPM running, is all.

bax

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