Answers to all the thoughts.
I run two styles of the Ivo. The regular Magnum series is the tapered one and perform better in acceleration and overall cruise speed. The real drawback is the leading edges are only protected by foil tape and that quickly degrades by sand,pebbles, other small stuff that gets sucked into it. The big issue is flying in the rain, which I like to do, mainly for giving the toy a bath. The rain drops eat away at that foil fast.
My second set is the Magnum Paddle series, the square tipped design and has leading edge protection using a this piece of stainless riveted to the blades. For backcountry/off airport flying it is ideal but performance is slightly degraded by maybe 5-8 %. The paddle blades run smoother mainly because of less tip flex over the regular magnum ones.
I fabricated my whole electric inflight adjustable set up and when machining the transfer rings that the brushes contact and ride on I polished them as much as I could, almost to a mirror finish. The first set of brushed lasted 40 hours or so, The second set made it 120 hours and I am on my 3rd set at 300 hours total time and they are about 1/2 gone so I am convinced the brushes do transfer and impregnate the ring surface with brush material and that adds to brush life for sure.
The ammeter idea for setting prop angle is at best suspect for the following reason. When traveling through the entire range the drive dogs that engage the planetary spool on the drive motor go from high stressed when in fine pitch to middle range where there is no stress at all to high stress at the full course pitch setting. As you move throughout the entire range the ammeter will show initially a high amp draw. then in the middle range almost no draw and then on the way to high pitch high draw again. Remembering where you are, ie am I on the range between fine and neutral, or nuetral to course ?? will be hard to predict with just an ammeter. I admit I do look at my ammeter gauge when traveling from any setting to fine pitch for landing and when the drive motor stalls or in the industry called "rotorlock" the amp gauge will show a big needle deflection. When I see that I know I am at the end range of the prop setting. YMMV and
IMHO... Sorry for the long winded comments guys.
Tailwinds
Ben
From: Kelly Troyer <keltro@att.net>
Subject: [FlyRotary] IVO Question (was) Static rpm
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Sunday, October 18, 2009, 6:31 AM
Stephen,
Impressive !!..................Love the V-8 sound...............I presume you have both
the "Ivo" 30 to 90 and 45 to 90 pitch blades..............With your hp I would also
presume the 45 to 90 are needed to hold back all that hp.................I also have the
electric "Ivo" (74", 30 to 90 pitch , 3 blades) for my estimated 180 hp 13B that has
yet to be run................Several of the Rotary group are currently flying both ahead
(and behind) the "Ivo" with varying blade lengths...............From your experience
with both pitch blades and with the ability to overpower them at will with shear brute
hp do you think that I will need the higher pitch 45 to 90 blades for my approx 180
hp 13B ??.................
Thanks,
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Original message from stephen haas <admin@haaspowerair.com>: --------------
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Hi Guys... Just to add some data to the conversation.
I run a Ivo prop and switch between two different blade designs. Both are 76" dia and both are set up for inflight adjustability.
facts.
my ignition has 4400 rpm chips in them. redrive ratio is 1.43-1. I usually run 4400 engine rpm on take off and climb. this gives a prop rpm of 3076 and at 50f temp that works out to tip speed of 695.5 and .922 mach. Prop pulls real strong at this rpm, anything over that and it starts to lay down. It appears my Ivo is pretty effecient till about .94 or so. I have not had the balls to pull the chips out and take it to 1.0 mach but...
the motor was just under the chip rpm or about 4350 or so. temp was 26f, prop rpm around 3000, close to mach .93. The plane pulls good and as you can hear the motor makes alot more noise then the prop does. I have several guys tell me no way that I can run the prop that fast but proof is hard to deny.
Ben
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