Constant speed prop on a gyro, anyone care to share the experience?

Barry M14

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I had a WarpDrive in flight adjustable and I found it almost completely useless below 2500 feet. Rotax recommends all day cruise setting to be 35 inches of manifold pressure at 5500 RPM. If I set the prop for 5700 RPM on full power takeoff which is only 100 RPM less than the 5800 max that Rotax recommends (for a climb setting ) for under 5 min. At that setting I can just get about 33.8 Inches of manifold pressure at 5500RPM in straight and level flight. I have a 914 So as I go to 3-5 thousand feet and higher is when I would wish for the option of an in flight adjustable prop especially because of the 914 is still making full power at high altitude. I have found that since I switched to gyros that scenario happens very little now so I got rid of it
The next time I go over New York at 9,500 ft. I will look at my manifold pressure gauge and see how high it will go at 5500 RPM. I am guessing it will be around 32 Inches of manifold pressure.
I would think a 912 would benefit far less than a 914.
 

ventana7

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Since gyros generally fly close to the ground (minimal difference between take-off and cruise altitude and minimal time spent climbing) and usually take-off from runways far longer than needed, for many there is often not a lot to be gained by being able to switch from fine to coarse pitch. But as others indicated in the West there might be other considerations. My home airport in Colorado is 7,500' and the passes on all sides of me require me to fly at up to 11,500' or more which in summer is a DA of 14,000'+. If I go to the plains east of me only 70 miles away near Denver I will be at 5,000'. Repitching is almost a necessity.

A few years ago when I flew to Oshkosh I had to stop and repitch my ground adjustable prop going each way because there just was no way I could use the same pitch at 1,000' as I had used at my home elevations.
 
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To give you guys more concrete details, I will do some cruise comparisons this weekend. I can fly with the propeller pitch fixed at the ground take-off value (same as it would be in a ground-adjustable prop) and check my cruise speed, then compare that in the same conditions and altitude with cruise speed with CS mode turned back on.
 

Resasi

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Apologies for bumping a 5-month-old thread but I disagree with Abid on this one. He is in Florida so he only flies at really low altitudes (probably never even gets to 1000'), but the thinner the air gets, the more critical a CS prop becomes. I initially had a ground-adjustable prop and replacing it with a DUC (French) CS prop and it made an enormous difference. (I only have a Rotax 912.)
Agreed.

If the area to be flown from is fairly flat, whether at sea level or 7000’ feet a ground adjustable prop, if set correctly for the commonly used home airfield alt, will cope with the variation in altitude commonly flown in gyros for a reasonable range from that field.

If however there will be quite large variations in terrain alt and density alt around the home airfield, that is when an inflight variable pitch prop comes into its own...or if on a long flight with a fixed pitch, then be prepared to fine tune along the way.
 

StanFoster

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Speaking from a little experience...I put an Ivo Magnum variable pitch prop on my SparrowHawk. That thing really made a difference on take off....
cruise...and top end. Its in one of my SparrowHawk threads in the archives here...but I recall gaining 8-10 mph.

I did have trouble with losing the electical connection once in awhile, an it was stuck at the pitch it was at. .

So when its working...I grade it an A. Overall a grade C with the fiddling I had to do with it.
 

GyroRon

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I am not a fan of the ivo prop in that the prop blades are held to the hub by friction between the inner and outer prop hub plates, with a knurled surface. If the prop ever gets loose in the hub it will get very loose very quickly, and can eject a blade, which obviously can have deadly consequences

But saying that, I had a Ivo prop with electric adjust on a plane I used to own, a titan Tornado II with a 80hp Rotax 912. It did allow a slightly better cruise speed than the warp drive fixed pitch prop I ended up putting on the plane. It really didn't make much difference on take off and climbout, but in cruise you could add in pitch and load the engine up and pick up a few mph.

The electric adust pitch on the ivo makes it illegal for sport pilots. BUT........ It is very simple to remove the electric adjust portion of the prop and just make the prop fixed pitch if you ever needed to make it Legal for SP. Another option would be to move the switch for adjustment to some area that would be considered not accessible in flight, and it could still be adjustable and be legal.
 

Smack

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Has anyone got any first-hand knowledge of a hydraulic adj prop used on a Rotax?
 
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Yes, the DUC prop I'm using is hydraulic, driven by an electric pump. So you never need to rebrush motors like you do with Ivo and others, and it's been 100% reliable in the nearly 3 years that I've had it, unlike the Ivo which I flew with once in Florida and which failed immediately (due to a loose wire preventing pitch adjustment).
 

fara

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I am not a fan of the ivo prop in that the prop blades are held to the hub by friction between the inner and outer prop hub plates, with a knurled surface. If the prop ever gets loose in the hub it will get very loose very quickly, and can eject a blade, which obviously can have deadly consequences

But saying that, I had a Ivo prop with electric adjust on a plane I used to own, a titan Tornado II with a 80hp Rotax 912. It did allow a slightly better cruise speed than the warp drive fixed pitch prop I ended up putting on the plane. It really didn't make much difference on take off and climbout, but in cruise you could add in pitch and load the engine up and pick up a few mph.

The electric adust pitch on the ivo makes it illegal for sport pilots. BUT........ It is very simple to remove the electric adjust portion of the prop and just make the prop fixed pitch if you ever needed to make it Legal for SP. Another option would be to move the switch for adjustment to some area that would be considered not accessible in flight, and it could still be adjustable and be legal.
Legally speaking once you install an in flight adjustable prop of any type on an aircraft it can never be again flown or sold to a Sport Pilot and fit under LSA definition. Personally I think that rule is downright stupid. One should be able to change the prop to a fixed pitch one and bring it back under LSA and fy it as a Sport Pilot
 

fara

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Yes, the DUC prop I'm using is hydraulic, driven by an electric pump. So you never need to rebrush motors like you do with Ivo and others, and it's been 100% reliable in the nearly 3 years that I've had it, unlike the Ivo which I flew with once in Florida and which failed immediately (due to a loose wire preventing pitch adjustment).
Well loose wire will fail any electric system including a fuel pump like in 914 or 915iS.
The trick with Ivo prop we found is to throw away the circuit breaker they give you and instead use a 5 amp Tyco circuit breaker. It pops before it allows your motor etc. to burn out. You can then simply reset the breaker and you are good to go
 

Smack

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Wasn't there some talk about changing the LSA rules to allow 'pitch adjustable' props?
Yes, I know that they talk about lots of things (weight increase, adding gyros, etc.), but I wouldn't let this "you can't sell it to a Sport Pilot" be the top of the argument or dissuade someone from this optimization.
 

All_In

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Legally speaking once you install an in flight adjustable prop of any type on an aircraft it can never be again flown or sold to a Sport Pilot and fit under LSA definition. Personally I think that rule is downright stupid. One should be able to change the prop to a fixed pitch one and bring it back under LSA and fy it as a Sport Pilot
I did not know you could not change it back.
 
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