Hello Chuck,

    If I remember correctly you had a 20B in a Velocity, and if that is
correct you may be able to help me out quite a bit.  I have a Velocity SUV
myself, and it is using a 20B and Tracy's 6 pinion re-drive.  What I need
help with is the propeller dilemma.  I can't afford the $10,000 constant
speed prop so I'm basically down to the IVO as second runner up.  The trick
is to avoid going to the ugly 4 blade configuration (Scissors configuration
with the IVO.)  I would really like to stay with the 3 blade for aesthetics
if I can use a long enough high pitch blade to handle the 300+ HP range of
the 20B.  Can you tell me what the distance from your hub center to the
ground is on you airplane and give me some advice on how long a prop could
be used and still have adequate ground clearance for rotation and the
inevitable bounced landing now and then.

Thanks for the help,
Robin

Robin, the 3 blade IVO prop will work just fine for your application. Make
sure you get the deep pitch (50"-110") version. You'll need to have it
balanceed on the plane and then mark the blades and position. In my brief
testing to date, I've had it over 200 mph @ 4,500 rpm, so there's a lot
left to go.

I have a std Velocity and thus my grd clearance will accomodate only a 69"
diameter, although the factory suggests 68". I don't know what the heigth
restriction is on the SUV, but Duane or Scott will know. I actually flew it
with 72" diameter, but worried about a prop strike at takeoff which I
understand is the only concern. Mark Machado has flown a 76" on a std, but
that's way too much dia. .

Remember to re-torque every flight as it will loosen up until the knurling
is fully imbedded into the composite prop blade. Also, I tighten to 75
ft-lbs which is closer to the correct bolt torquing (85?) per the ASME
stds. Ivo said that he specs 65 because of some FAA/NTSB rule, but he said
75 was fine. It also seats the blades quicker. I assume your getting the
in-flight adjustable version.

In my last flight (when the oil cooler broke), one of the electric pitch
wires came loose, and I couldn't add pitch. Instead of t/o of 4,500 rpm
which is normal, I was at 5,500 rpm and only doing about 100 kts. I didn't
realize I was in low pitch and couldn't add pitch until I was airborne. In
the future, I've decided to take off with close to full pitch because the
turbo 20B has so much power that it doesn't matter. I've taken off this
several times at full pitch. You actually could use a fixed high pitch prop
because of the power.

During initial  run up testing, I tied down the plane (car tow straps tied
to the gear legs and tied to 1" steel bars 12" into concrete floor), used a
medium to low pitch and was able to run the engine at 4-5,000 rpm to see
how everything worked. It will probably over heat after about 5 mins, but
you can safely observe the engine/prop in flight conditions.

The IVO prop actually saved my fuselage on my crash landing (didn't get
main gear down) after the oil cooler failure and engine stoppage. The 2
blades on the bottom broke about a third from the end, but the remaining
blade were strong enough to carry the plane off the grd for over 500' until
I came to rest in the dirt. Only my wing tips touched the runway. Duane
looked at it and was amazed at how little damage there was, and so was the
FAA, who called it only an incident, instead of and accident, becaue there
was so little damage. Hope this helps.

Chuck H

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