IVO Prop Question

For any of you flying behind a IVO in-flight adjustable prop (help Ross!); I was wondering if you have any experience flying an RV behind a three blade Magnum with the lowe pitched prop. My blades don't have a "+" sign on the hub (which means) high pitch which makes sense I suppose since they were on a Glastar originally with the 13B engine I bought. Anyway, I was wondering if anyone had any experience of what kind of performance hit I could expect by flying with this prop initially. If it is too much then I suppose I might as well sell it and get on the waiting list for CATO prop, etc.

Thanks for any informationl.

Doug Lomheim
RV-9A, Mazda 13B, FWF
OK City, OK

Ivoprop experience

Setting the low pitch stop for your static RPM should tell you if you will need the high pitch blades. If you use more than a quarter of the pitch travel for the low pitch stop, then you could use the high pitch blades. They start at about this point in the pitch travel.

Absolutely place the tape between the blades and inspect the tape before every flight!

I have flown the standrard pitch and the high pitch Ivoprop Magnum blades on my RV-3. From a 3 blade 76" diameter to a 2 blade 66" diameter in 2" increments on the diameter.

Replacement blades were relatively inexpensive. About $220 each. I don't know what they are now, but the price of the propeller assembly hasn't increased by much.

I was one of Ivo's volunteer test pilots. About 150 hours TT.

Regards,
Jim Ayers

I think the low pitched 3 blade, 76 inch Magnum may not work well on an RV with over 150hp but this depends a bit on what rpm you are turning it. I turn mine at 2100 rpm for takeoff, climb and cruise- just adjust manifold pressure and pitch.

I am fully coarse in cruise at anything above 30 inches MAP and 10,000 feet to keep it at 2100 rpm and this is with the high pitched version. I make about 160hp at 38 inches and 4600 engine rpm with a 2.2 to 1 reduction ratio.

You will be turning quite a bit more rpm with your 13B probably and if you have a 2.17 ratio, prop rpm will probably be around 2700 so this takes a lot more power. You may be ok as far as absorbing power with the low pitched version but not sure about the speed department. I'd try it and see first. If you have to run much more than neutral pitch during your run up to stay below 2700 prop rpm, you probably won't have enough prop in cruise.

Like Jim said, new IVO blades are cheap. I think you may find takeoff and cruise somewhat uninspiring with a Catto and your 13B.