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Hi Dennis,
Yes, here's some snippets of the data I recorded on the trip
Static at take off was 6200 rpm (a bit higher due to the colder (32F) dense air - my nominal static is 6000). It is clear the prop (Performance 74dx88p) is stalled on take off roll as you can hear the "wop,wop" as it stalls/unstalls as the cowl/prop interaction occurs. After lift off the prop unstalls and loads-up pulling the rpm down to 5900-6000. During more nominal temperatures (50F on up) I do not notice the stalled effect.
Fully loaded max rate of climb I saw on trip after take off was 1600 fpm. Most were closer to 1400 fpm at gross weight. My take off weight fully loaded is 1750 lbs.
Here are a few of the data points I logged on the trip
5800 rpm and 8 GPH fuel burn gave a TAS of 164 MPH at 6500 MSL, Oil 175F Coolant 170F OAT 43F
6000 rpm and 9 GPH fuel burn gave a TAS of 175 MPH at 9600 MSL, Oil 160F Coolant 160F OAT 39F
6400 rpm and 10.3 GPH fuel burn gave a TAS of 191 MPH at 7500 MSL, Oil 175 Coolant 175 OAT 30F
Keep in mind that my heavy RV-6A is a bit on the draggy side with a overly large bottom cowl opening and two mufflers in the slip stream. I have an "older" 13B (91 turbo block) so do not produce quite the HPof the newer Rensis engine.
I wouldn't be too concerned about your static at this point, Dennis. Yes, it could stand to be a bit higher, but while I did have a 76dx88p prop initially,I later had 2" removed from the diameter to bring my static up from 5800 to 6000 rpm. Also I found with the 76 dia prop, the "P" factor, Prop Stream or whatever, I did not have enough rudder control on initial roll at WOT. Made for some exciting early take offs, also cutting the prop provided a bit more ground clearance.
It seems few folks get the static power they are looking for without some tinkering with the induction/exhaust. You may find that you are a bit over propped, but I certainly would not do anything to the prop at this point. My personal opinion.
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html
----- Original Message ----- From: "Dennis Haverlah" <clouduster@austin.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, November 07, 2006 9:59 AM
Subject: [FlyRotary] Normal Engine Paramaters
Ed:
Glad to hear you had an uneventful 1500 mile trip!! Would you post your nominal static rpm, cruse rpm and gph fuel burn. Also any cruise air speed numbers and altitudes would help. Are you still using an 88pX76dia prop? What max. climb rates are you getting?
I am about to start the auto-tune exercise on my ECM.. I've got the Catto 88X76 composite 2 blade prop using Tracy's 2.81 psru and so far have only been able to get 5400 rpm static. I hope to paint and assemble the A/C in the next 2 months.
Dennis H.
RV 7A, James Shark cowl
Tracy's ECM, EM, 2.8 psru
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