Tracy,

 

 My RV static RPM is 5350 - 5400 with my Warnke prop which seems pretty good. This is with a 2.17 ratio RD-1. When the prop unloads in level flight what should I expect to see for RPM at full power? Max RPM I've seen in level flight, full throttle, 8,000' was about 5700 - 5800 but I may not have given things enough time to settle out. What are people typically setting for cruise RPMs/MP? With the limited flight testing I've done so far my engine feels pretty comfortable at around 5,000 RPM and that has been a typical power setting for me to date. Still getting used to the different sounds and sight picture with the high RPMs and cheekless cowl.

 

 At higher power settings/RPM it feels "busy" - hard to describe and it may just be a comfort factor thing that I need to get used to.

 

Mike Wills

RV-4 N144MW

----- Original Message -----

From: Tracy Crook

To: Rotary motors in aircraft

Sent: Wednesday, March 11, 2009 8:48 AM

Subject: [FlyRotary] Re: IVO Prop

Yep, should have thought about pushers when I wrote that comment.  The IVO seems to work well on pushers since the stalled inner part of the blades is in turbulent air and doesn't cost them the drag that it does on tractors.  Tractors are pretty much stuck with high priced variable pitch stuff like MT to equal the performance of a well matched fixed pitch prop.

What is well matched?    If you are running an RD-1B the static rpm should be 5100 - 5500.   With the RD-1C it should be 5900 - 6300 rpm.    If you get less than that, it isn't a well matched prop.  This also assumes that the engine is performing up to par of course. The exact number depends on what you want to optomize, climb performance or cruise economy.

One more caveat:  If you are putting it on a plane with a cruise speed below ~ 150 MPH, the IVO also works on tractors as well.  On my RV-4 the IVO cut top speed about 15 mph. and around 10 mph from cruise compared to a well matched fixed pitch prop.

Tracy

On Wed, Mar 11, 2009 at 12:41 AM, John Slade <sladerj@sbcglobal.net> wrote:

>I didn't know anyone had ever had any success with an IVO. Tell me more.
What do you want to know? Its a very well engineered piece of equipment. The CF blades are hollow and have a steel rod running to the hub. Activating the motor via brushes twists the steel and thus twists the blades equally. The twist change is quite visible. There were problems with the individual blades slipping on the hub. This has been solved by providing a knurled hub, and not selling to guys with Lycomings. The IVO is available for rotary, subaru, Franklin 6 and other less "pulsy" engines. After the first 15 hours or so my blades have hardly taken any extra torque.

My performance is greatly enhanced compared to the fixed pitch Performance prop. Static with the wood prop was around 4500. With the IVO on full fine I get closer to 5400 which gives me access to a lot more power on take off. I've never done a "high speed" run with the IVO, but I've had 180 kts indicated at 2000' a few times without much effort, and without ever going to the full course setting. Another nice bonus is that throttled back on full fine for landing, the prop acts like a brake. Its much easier to land and stop than the fixed pitch that's pushing you along fairly well, even at idle.

I know a Velocity driver (Mike Watson) who also uses an IVO (Franklin 6) and is very happy with it after around 5 years of use.

The factory people are very easy to deal with and very helpful.

The Cozy Girrrls are installing an IVO. What better recommendation could you want? :)

Regards,
John Slade
Turbo Rotary Cozy IV, N96PM
98.1 Hrs.

Mike Wills wrote:

Mike Wills
RV-4 N144MW

----- Original Message ----- From: "John Slade" <sladerj@sbcglobal.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, March 10, 2009 10:30 AM
Subject: [FlyRotary] Re: Ground Testing

The IVO electric in-flight adjustable costs around $2350. I'm very pleased with mine. My "spare" is a $2700 fixed pitch wood prop thats a piece of art, but doesn't work anywhere near as well.
John

Tracy Crook wrote:
A variable pitch prop would be nice to get the best of both worlds but it's an expensive option and $10,000 buys a lot of gas.



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