IVO pireps wanted.. high performance/high speed...

Dave S wrote in message thlink.net...
Ok.. question for those out there with some hands on experience with the
IVO Magnum series electric inflight-adjustable props.

What has been your experience with this product.. Any pro's or cons
based on your experience...

Has the product met your expectations...

Where I am coming from: working with a builder making a Mazda powered
Velocity. We have kicked around the idea of a controllable
pitch/quasi-constant speed propeller.

I have corresponded with Tracy Crook (www.rotaryaviation.com) who has a
flying RV-4 with a Mazda rotary. His experience was that he had a loss
of top end speed with the IVO product compared to a fixed pitch prop...
It was enough of a difference that he has chosen not to research using
the product any further in his later applications. I am not sure if this
is because the blades are unable to "twist" enough or what.

This is somewhat disheartening, because the IVO seemed like a cost
effective possibility. The electric MT is out of my price range, and I
cant seem to find any other electric actuated in-flight adjustable props
that can handle 200-250 hp.

I am curious if others have experienced similar outcomes using this
propeller in applications running in the 170-200 kt/200-250 hp range

Dave

This came over the Velocity mailing list --

=============================================

Carbureted/magneto Franklin, electric IVO.
Nothing special.

I wanted to get more data, but clouds below 5000 was a problem.

The best speed we saw was at 7500 feet altitude, full throttle, the first
altitude where we actually
achieved full open throttle.
182KTS TAS, 2520 RPM, 23.1 inches MAP, 12.4GPH.

I was more impressed however, with putting more pitch in the prop. At this
same altitude, I took data at progressively slower RPM's (same throttle).
174KTS TAS, 2300 RPM, 23.5 inches MAP, 10.8GPH.

We stabilized a climb through 8000 feet at 120 kts indicated, 144kts true at
700FPM rate.

Levelling at 9000, going through various MAP/RPM settings, I was impressed
by the economies achieved:
KTS TAS RPM MAP GPH
1 147 2370 19.7 9.5
2 180 2520 21.8 12
3 175 2400 21.9 11.2
4 162 2200 22.1 9.9

At line 1, this is at 120 kts indicated (where I started data collection),
147TAS. This is partial throttle operation. Not bad for 9.5GPH, but look
at line 4, full throttle, slower RPM. Faster speed, with just a little more
fuel flow. I find it surprising that pumping losses account for a 5%
penalty between lines 1 and 4. That's 15.5 nautical miles/gal and 16.4
nautical miles/gal for lines 1 and 4.

The most economical was at 7500 feet:
174KTS TAS 2300RPM 23.5MAP 10.8GPH, making that 16.1 nm/gallon. I don't
know why I didn't get at data point at 2200RPM. It would have been better
yet.
What this says to me is pick a MAP/RPM combo that is the economy setting you
want, then fly the altitude that will give you that power setting at WOT.

It was hot too. 95F on the ground, adding about 3000' for density altitude.