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
From: Al Gietzen <ALVentures@cox.net>
Subject: [FlyRotary] Static rpm
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Saturday, October 17, 2009, 10:13 AM
Only cuz it was mentioned....I usually do achieve about 6000 rpm static. I am using a 2nd gen turbo block with a medium street port. I am guessin' the street port brings my static up a bit. This is with a 2.17 B drive from Tracy and an Ivo in flight adjustable prop set at a fine pitch. When I go course, it drops about 200 rpm.
At some point you’ll want to consider a larger prop or more pitch. Typically your static rpm with cruise pitch should be in the neighborhood of 2450-2550 (so 5300 – 5500 on the engine). As it is ,you’ll find you can’t go WOT in flight without over-speeding your prop. Are you sure the IVO is going to full pitch?
I get about 5400 static, and can reach about 6300-6350 in flight. That’s a bit over 2900 on the Catto prop, which is speced for 3000 max. I’d guess the max on the IVO should be a bit less.
Anyway, you must be generating serious power. What are the specs on your prop?
Al G
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