B

Brunop

Member
In assembling the Sensenich prop I'm not able to set the pitch from 1 to 5. Seems like it is restricted from 3 to 4.5.

Did I get something wrong? Wasn't able to figure the mistake by reading the manual.

Thanks in advance for your support,

Bruno
 
Bruno,
I believe that the RV-12 hub is set up per Van's request that way. I think it is a way to limit the top speed to keep it legal in the USA. Could be wrong though.
Paul LeDoux
RV120495
Forward fuselage
 
And then throw in the two blade vs three blade, and I am still lost in the fine points of it all.
IF Vans actually limits LSA qualifying speed with prop pitch, apparently they overdone it I guess?
 
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.
 
Now THAT is far more believeable.

Peterk said:
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.
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I learn something every day. Does anyone know if the modified pitch device is used on all Sensenich props that are installed on the Rotax engine? If not why not?:confused:
 
can't answer that one...they do have a pitch stop on all that keeps it in the 1 to 5 range. Van's probably had them put ours on as a service to us. sensenich does post on their website the different engines and propeller lengths available for this prop. they also state more than once to set the pitch where it avoids "overspeeding" the prop...exceeding the engine manufacturer's maximum recommended RPM. Your prop from Van's has a pitch stop that almost guarantees you won't.
 
E. D. Eliot said:
that Van's would offer a three bladed prop as part of the kit.:cool::cool::cool::cool::cool::cool::cool::cool:
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Flight testing was done of a three blade ground adjustable propeller supplied by Sensenich.
The propeller that was supplied, was found to have a significant enough performance reduction (compared to the two blade, on an RV-12) that the decision was made to not offer it.
 
Thanks, Scott

for the information - Mr Catto, are you listening and/or interested in helping Van's satisfy mu lust for a three bladed propeller?
 
Sensenich Props.

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!
 
Its all about the design!

Couple of things to thing about. When it come to Vans design they think about where the plane will be in 20 years. If built as an ELSA in the USA the Data Plate has Vans Inc as the builder. So they try to design the plane to last. Now think about who will have your 12 in 20 years. The next owner of your 12 might not have that personal knowledge of the build and set up that you would have. So the 12 design has to have reliability built into it. In other word keep it simple stupid. The infamous KISS principle. IMHO the prop setup tries to incorporate this principle. Its adjustable because an owner might live at sea level or he might live in the mountains at say 8000 feet msl. But it also limited on purpose so some owner 20 years from now doesn't fry his engine because hes not as informed to the limitations of the engine and design as the builder was.:confused: Furthermore because of the limitations of the design itself you really don't need anymore movement on the adjustment. Example, set pitch so that Static Runup RPM is not less than approx 4950 RPM and then the top RPM will be limited by your speed, which usually at standard temps and pressure at lower altitude will occure when you reach 120kts you will be at approx 5500 RPM. So increasing pitch drags the RPM down below Rotax suggested operating parameters on takeoff, decreasing pitch means reaching 5500 RPM before reaching 120kts. So there you are, no need for any more movement than Vans has it set for.;) Disclaimer; this all based on my own personal experience so far.:D
 
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splitty said:
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!
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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).
 
rvbuilder2002 said:
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).
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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!
 
I agree and like the way you think.

Peterk said:
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!
Click to expand...
 
Peterk said:
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!
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Peter, I of course agree that that (and reducing weight) is the best approach to increasing performance, but I am highly skeptical that any of the other drag reduction mods people have done, have actually produced a measurable speed increase.
Considering that the wheel fairings and nose leg fairing only increased speed about 4 kts combined (verified with some careful measuring), it is unlikely that the main gear intersection fairings do much for a measurable drag reduction (though I agree they look nice)
 
Performance and speed claims

What is lacking in all of these type of discussions (alternate engine/3-blade prop/fairings) is for someone who has done it, and there are a few, to fly the speed boxes and publish some actual data.

Bearing in mind, of course, that to remain an LSA the aircraft must continuously meet the LSA definitions ;).

Since the unmodified RV-12 already bumps up against the LSA speed limitiation, it seems logical to assume, since no actual data being published, most of these mods either would take the aircraft outside the LSA definitions or degrade the performance of the RV-12, or do not provide a measureable improvement.

Tony
 
The propeller on the Vans kit works just fine. It is light, easy to adjust, and makes the 12 perform well. Solo I have no problem exceeding 120 KTS before I hit 5500 RPM. A 3 blade may look sexy to some. Go for it! Scott has clearly stated the Sensenich 3 blade did not perform as well as the 2. I'd rather have a fast 2 blade than a slow 3 blade.

I am sure that with enough time and money, someone will come up with a prop that will out perform the stock one. I doubt that it will be Vans, for obvious reasons. Vans is trying to make an honest LSA that handles and performs well. They succeeded. Sure, there are always ways to improve any airplane. Heck, they are still trying different props on the C-130. Unless there is a solid market, the cost to develop a new prop for the RV-12 will be prohibitive.In the mean time, I will enjoy flying N815W and not care that with a new wonder prop I might go a bit faster.
 
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