Sonex 1084

[sonex1084]

Sonex 1084 flew for the first time today. It was actually an accidental flight that started as a high speed taxi test. The airplane just didn't want to stay on the ground. It got light really fast and up I went. Once I broke ground I decided, "what the hell, I might as well keep going." Unfortunately the EGTs on the #2 and 4 cylinders quickly climbed into the yellow to 1318 degrees. I had to lower the nose to increase the airspeed and even reduce the throttle a bit to keep the EGTs under control. Because of that it was just a quick loop around the pattern to a landing. The CHTs for all the cylinders stayed in the green as well as the 1 and 3 EGTs. Since I was busy flying the plane back to a landing and working with the EGTs, I didn't record the actual temps other than the high EGT. I'm flying an aerovee with and aeroinjector.

A A&P buddy who flies a VW on a gyro copter suggested I might be running too lean and I should enriched the mixture. Any words of wisdom?

Thanks,
Matt

[NWade]

Matt -

EGT temps should be taken with a grain of salt. If CHTs are good and all other instrument indications are fine, then the engine is probably running well and its no cause for alarm.

Here's an article from Mike Bush on the subject: https://resources.savvyaviation.com/wp- ... bunked.pdf

And here are two good webinars he's given on EGTs and what they mean:
https://www.eaa.org/videos/1316946190001
https://www.eaa.org/videos/994808107001

Congrats on your first flight! Sonex #1339 is going into paint in a couple of weeks and will hopefully follow your baby into the skies soon.

--Noel

[Direct C51]

At the risk of sounding like a broken record, absolute EGT values mean NOTHING. Only the difference from peak is useful. I really hope someone doesn’t crash their plane worrying about EGTs, especially in the 1300s. If your CHT is in the green, you are fine! Lowering the nose isn’t going to do much. The only way to really lower EGT is reduced power or a richer mixture (or leaner if on the lean side of peak). Not that this matters anyhow, since absolute EGT means nothing.

[Matt541]

Congrats on your accidental first flight!

I've noticed mine gets pretty light around 25 mph indicated, so that's as fast as I've done taxi testing. She wants to fly!

[SonexN76ET]

Where did you get the idea that EGT’s in the low 1300’s was “in the yellow”? Why don’t you reference the AeroVee manual. What does it say is the maximum EGT you can have for five minutes during climb? What is the max sustained EGT specified in the manual?

Also a gyrocopter engine has to be set up for flying with less airflow through the cylinders as a pusher configuration and lower air speeds so don’t use that as a comparison to an AeroVee in a Sonex.

[pappas]

I agree that you shouldn't worry about EGT's in the 1,300's. I raised my yellow warning to 1425 and my red warning to 1450 just to stop the annoying alarms.

I usually cruise my turbo leaned to just under 1400 with my CHT's under 385. That gives me about 137 mph at 3000 rpm, 30 inches of map, and 5.7 gph burn. As long as CHT's are green the EGT indicated temps don't mean much. The Mike Bush articles are a MUST read. Really. They will allow you to concentrate on the flying and remove an unnecessary distraction from your early flights. It will take about 50 hours for all the temps to normalize and for you to learn the engine and how to run it.

Have fun, congratulations on your first flight. Your experience is exactly how I made my first flight in my Waiex B. Totally accidental and totally fun.

[Barry63]

Congrats on your first flight!!