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difference in prop types
not sure if this is the right forum to put this in but what is the difference between all the different types of wooden props. I have seen type a, c, d, and e. I was wanting to order a new prop for my os 70 4 stroke and wasnt sure the difference between all the props.
thanks Jeff |
RE: difference in prop types
Not all props are created equal to put it simply. In general wide bladed props work best with 4 stroke engines while narrow blades work well with screaming 2 strokes. However it seems there are no hard rules, I prefer to grab a handful of props in the general size range and fly each one then decide.
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RE: difference in prop types
Try a 12x7 and 12x8 on the engine
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RE: difference in prop types
Have you looked up the manufacturers specifications to see what is a good starting point???
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RE: difference in prop types
Depending on the drag factor of the airframe the engine is to be used in, I prop about 700-1500 RPM less (static) than the maximum RPM of the engine.
If the engine is to be installed in a WW-I biplane start W/the smaller spec'ed props. If it's going into a P-51 Mustang, go W/the larger spec'ed props. |
RE: difference in prop types
I like a 13x6 Master Airscrew K Series on my 70 four stroke. As already stated, try a few to see what you like.
edit the K series is plastic, didn't read the original post very well |
RE: difference in prop types
Iuse 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines.
In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine. I allow slightly higher rpm limits on smaller 4S engines. |
RE: difference in prop types
ORIGINAL: jeffie8696 I use 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines. In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine. I allow slightly higher rpm limits on smaller 4S engines. My CDI fired Saito FA91S was spinning a 15 x 4 @ 10,300, a bit more than I liked. I went to a 15 x 5 & the revs dropped to 9,700, a bit more cushion against overreving in the air. |
RE: difference in prop types
ORIGINAL: SrTelemaster150 ORIGINAL: jeffie8696 I use 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines. In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine. I allow slightly higher rpm limits on smaller 4S engines. My CDI fired Saito FA91S was spinning a 15 x 4 @ 10,300, a bit more than I liked. I went to a 15 x 5 & the revs dropped to 9,700, a bit more cushion against overreving in the air. |
RE: difference in prop types
ORIGINAL: 1QwkSport2.5r ORIGINAL: SrTelemaster150 ORIGINAL: jeffie8696 I use 10,000 rpm as a limit for static rpms on any prop for mid sized 4S engines. In other words I ground test any prop I am interested in trying and if it turns over 10,000 static it might over rev the engine and cause wear, stress on the engine. I allow slightly higher rpm limits on smaller 4S engines. My CDI fired Saito FA91S was spinning a 15 x 4 @ 10,300, a bit more than I liked. I went to a 15 x 5 & the revs dropped to 9,700, a bit more cushion against overreving in the air. Mine idles @ 1700 RPM W/CDI firing things off 11* BTDC @ idle. Initial full advance timing setting is 35* BTDC. |
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