Sensenich has different pitch recommendations on THAT prop for different engines. If you put the pitch outside of the range set for the twelve (remove the restrictor) it becomes difficult to keep the RPM's under the 5800 limit, etc. It is an engine issue, not a cruise speed issue. The 5800 RPM limit set by Rotax is easily accessible in the air by setting your pitch per Van's recommendations...5000 static WOT on the ground.
that Van's would offer a three bladed prop as part of the kit.![]()
I'm sure you will find that the Reduction in blade adjustment is done on the RV -12 Purely for SLSA speed retention purposes..... Lets face it theres Heaps of other Rotax powered aircraft around that can cruise in the 160 MPH bracket...........Just a though..!! Yes Bob Catto seems to be able to make some fine High performance Probs for different Engine & Airframe combinations!
No, as Jet Guy already mentioned, it is to zero in on the range that will actually work on an RV-12.
The standard propeller (not the RV-12 specific one) as supplied has a range to make it usable on just about any airplane that uses a 912. If it happens to be a very draggy airplane, it would require much less pitch than the RV-12 does, but because of the high drag at higher speeds, the max RPM would still be held in check. Because the RV-12 is relatively low drag as LSA airplanes go, the ideal pitch setting for most RV-12's is using nearly all of the pitch that would be available in the standard issue prop. (between 4 - 4.25 in the 1-5 scale).
It is true that an RV-12 prop. could be pitch a bit higher to gain a little more speed, but then you will be back to flying an airplane with take-off and climb performance about the same as a C-150 (barely half as good as an RV-12 with the prop set correctly).
Yes it is...but like all planes, if you cover each of the tiny little drag opportunities in the 12 you will gain more cruise speed than you will with a higher pitch on the existing prop. Your take-off and climb will stay excellent. When you get close to 120kts at max gross, at sea level, at standard temp, at Rotax' max continuous rpm recommendation...stop!
Yes it is...but like all planes, if you cover each of the tiny little drag opportunities in the 12 you will gain more cruise speed than you will with a higher pitch on the existing prop. Your take-off and climb will stay excellent. When you get close to 120kts at max gross, at sea level, at standard temp, at Rotax' max continuous rpm recommendation...stop!