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Brian,
I've attached a couple of poor quality images of a spreadsheet that I made. It calculates fuel system parameters from basic principles assuming a volumetric efficiency of 1 throughout. The blue cells are data that can be input and I've entered the best data I have for your system taken from your posts. The red cells are conditions that are not attainable due to either the staging threshold setting or pulse width limitations. The conditions for both tables are the same except for RPM. The 5000 RPM table shows what can happen if the primary injectors are too small for the staging threshold chosen. There is an intermediate region where the fuel flow required is more than the primaries can deliver at 5000 RPM although everything was fine at (arbitrarily chosen) 4000 RPM. It might be possible that tuning on the ground is alright, but when the RPM builds up in flight, the small primaries become a problem. I don't know if this is what is happening in your case, but it might be something to consider. If this were happening, fully opening the throttle in flight could result in operation within the attainable parameters again but above the staging threshold.
Steve
From: bktrub@aol.com
Subject: One more hour today
Date: Wed, 23 Mar 2011 20:06:26 -0400
To: flyrotary@lancaironline.net
Since we had a rare sunny day up here in Seattle, I went up flying for an hour after going through the mode 3, 6, then autotune and then a little touch up in mode 9, on the ground. It was running pretty smooth, but still does not like full throttle- maybe it's still a bit lean up there, but I'm thinking that maybe the Hushpower is too restrictive- I'm flying on 60% throttle, tuning with the mixture knob and the EGT is running around 1700, RPM is ~5000, MP- Damn, forgot to note- maybe 17"?. Funny thing, the coolant and oil is down around 110 f at these settings. Definitely need to block some of the cooling air. I don't know if the Dynon airspeed needs calibration, I did not have my GPS today, but was only getting about 110 MPH at that throttle setting. I did get one thing accomplished- I calibrated my AOA on the Dynon.
I'm starting to think about making my own very simple, robust muffler out of 321- pretty much a straight 2" tube within a 4" tube, with some holes and a few very firmly welded baffles. I'll try to get a drawing out and see what everyone thinks about it.
At least no one called the tower to report an aircraft in distress this time.
Brian Trubee
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