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rob2359

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OK 4 stroke. what prop & why? - 2007/01/02 01:14 Seems I am moving to 4 strokes.

That said, I just bought a Saito 72. Should be here end of the week. After I read everything. What prop should I look at & why.

I found an artical stating 12 X 8 to 14 X 8. The planes tested used the 13 X 8. No one says why and if I change from a 13 X 8 to 13 X 6, what am I gaining/giving up.

So for this engine on a 40 size stick or the 330 Extreme, what are you thought?

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davidchilds
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Re:OK 4 stroke. what prop & why? - 2007/01/02 16:08 Check the How to section for some info.

Dave

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Karl
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Re:OK 4 stroke. what prop & why? - 2007/01/02 23:33 Rob,

First off, you'll need to determine what kind of flying your going to do.

It had been suggested to me that for the 3D flying that I believe you are pursing as well, that a longer length, lower pitch wide prop would be preferable on my 70 OS FS.

With this engine, I tried the APC 14x4w which the OS will spin up to about 8750RPM. As you have seen, the UltraStick with the OS 70FS on it has pretty much unlimited vertical and I sure that if I ever develop the talent to be able to do more than a half rotation of a torque roll, the engine/prop combination would hang the plane there as long as I needed it to. One thing about the 14x4w props, when you chop the power, you need to have some airspeed or air space because they almost act like an airbrake. Fortunatly the 4strokes have the transition to get the plane moving again if you run out of either.

On the other hand, If you are looking to go for mach 3 passes of the field, I would recommend the 12x8, 13x8. This will give you the higher airspeed.

I have most of the props that you mentioned, 12x4, 12.75x3.75, 12x6, 12x7, 12x8, 13x4w, 14x4w that you can try out to see what the differences are.

Hope this helps.
Karl

Post edited by: Miller2149, at: 2007/01/02 23:35

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KevinKRC

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Re:OK 4 stroke. what prop & why? - 2007/02/14 12:49 When you get the engine read the manual.

There should be a recommended breakin prop. Then they will have a recommended range of prop sizes to work in.

If you overprop you can overheat and damage your engine so I would recommend sticking to the recommended range. Prop material will make a difference as well. Wood props are lighter than plastic but break easier on difficult landings. I like top flite wood and APC grey plastic props. But I have found that the APC 14x6 I bought for my Giles 202 and MAgnum 91 4 stroke will not fit on my prop shaft with the spinner I have, the hub is too thick so I have stuck with the Top Flite wood 14x6.

It's always something.

Kevin

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davidchilds
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Re:OK 4 stroke. what prop & why? - 2007/02/14 17:28 Gotta love buying a new prop, bringing it out to the field to test out only to find out you need to ream it out.