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Hi Al, glad to hear you are making progress. It sounds like all of us go down the same path of initial testing, some adjustments and than more testing. I agree with Steve that you are lugging the engine. On take off I run the engine at 6500-7000 rpm. That's where the best power is, and the prop develops the most thrust. I know people are trying to get the same numbers as Lycoming guys, but we can do better with our engines. For initial testing I like the IVO prop much better since you can let the engine run at it's best rpm. Good that you have the water temps under control. I noticed if I go past 240F on mine the power starts dropping.
my plane also had slight roll to the left and I shimmed one wing, but have not flown it yet. I also have an electric roll trim that I like. You should start flying with the test pilot and get some feel for it. That's what I did.
Again, let the engine rev higher, since right now your performance numbers for the same weight are very close to my engine, and should be 50% higher?
Bulent "Buly" Aliev
FXE Ft lauderdale, FL
Making a new exhaust w/muffler
On Sep 16, 2006, at 7:42 AM, Steve Brooks wrote:
Al,
Great news on the flight.
I don't recall what you prop arrangement is, but the RPM's that you have listed sound pretty low. Even with a variable pitch prop, I'd think that you'd want 2250-2300 at the prop, in cruise.
I can definitely relate to the high oil temperatures. I fought with mine for quite a while before I finally added additional inlet area. In my case I was using the main NACA scoop for everything. Ended up installing 2 armpit scoops @ 25 SQ IN each. One for the oil cooler, and the other for the intercooler and engine inlet air.
I just wonder if higher RPMs wouldn't improve cooling by increased flow.
Steve Brooks
Cozy MKIV N75CZ
Turbo 13B
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On Behalf Of Al Gietzen
Sent: Friday, September 15, 2006 2:09 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Flight test
Finally got the proper alignment of the planets (basically test pilot schedule) for further flight of Velocity 755V – 20B. Plane was in the air for ˝ hour this time, basically at level cruise orbiting the airport. OAT was about 90F and flight was at DA of about 7000’.
Since the first flight when oil temps were high, I added a temporary ram scoop under the ‘wing root’ oil cooler inlet. Oil temp reached near 230 during climb but later stabilized at 200 - 205F. Coolant stabilized at 180-185F.
I have video recording of EM2 display, and this time the pilot remembered to push the page button, so I have lots of data. For ‘% power’ readout of 65-70%, engine rpm was 4450, prop 2050 rpm, IAS (according to pilot) was about 145 kts. TAS readout on EM2 was 165-170 kts, but my calcs indicate this is about 5 kts too high. Fuel burn was indicating 16-18 gph running rich of peak.
The in-cowl radiator is handling most of the cooling load; with the wing root rad being very ineffective. This is consistent with the first flight results on the oil temps with the matching wing root oil cooler. The scoop added for the OC improved the air flow, but it is still marginal, with oil delta T of about 20F and air delta T of about 100F. It is likely the main issue is with the exit fairings. At least now it flies stably, so I can do some other changes and see the effects – hopefully get a differential pressure measurement set up.
Takeoff roll of about 1500’ at 1900# weight is quite good considering fixed pitch prop. It accelerates from rolling start to 60-65 kts nose lift in 6-7 seconds. This with an 85” pitch prop. Something special about Catto props.
The thing looks and sounds great, and I have to be happy that it went up, stayed up for ˝ hr, and made a perfect landing. Main issues right now are on-going problem with EC2 data corruption; apparently unique to my installation, and possibly ‘noise’ related; and the need for right aileron input in order to go straight, suggesting a need for wing incidence adjustment.
Al
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