It's that time of year in Houston when we have day after day of winds and low scudding cumulus clouds - it's usually legal VFR by noon, but it certainly isn't very fun VFR, so the challenge is finding something interesting to do. This wasn't horribly exctiting.....but it was something!
I have leaned airplane engines many different ways in my years of flying - mostly by ear, pulling the mixture back until the engine gets rough, then smoothing it out a bit (or leaving it a bit rough if I really want to stretch the range, and can live with it!). I used th original primitive analog single cylinder EGT's (which failed all the time in rental planes). I've used multi-cylinder bar-graph displays, both the LED kind and the similar displays on EFIS systems today. But my favorite way to look at EGT's has got to be the "time graph" representation on the GRT EFIS!
Here you can see it in the middle of the display:
This was taken after I had leaned, and the temps had settled down to "steady state". You can see where the temps started out low, then climbed as I leaned, and finally they "knee over" to the peak (or ROP, or LOP - whatever you want) EGT. It's not as pretty as usual - I was scudding along under the clouds at 1,000' in the bumps, and the engine doesn't really lean that nice in the thick air at 75% power. If this had been at altitude, you would have seen the four EGT's lay right on top of each other when the engine gets to the "sweet spot", with the digital temps being clustered within 10 degrees of each other. What has always been of interest to me is how far apart the temps are when the engine is running too rich - the lines are the same shape, but the temperature deltas are large.
To show how the graph works, I shot a little movie that you can find here. It's pretty bumpy, but if you've never seen this work, it will give you the idea.
Maybe it's just the way my brain works, but it is so much easier to see what the temps are doing and how the engine is leaning with the graph rather than bars, where I have to interpret the numbers. I think it is essentially an Analog versus Digital argument - the "analog" graph is easier to understand at a glance. It may work differently for others!
Anyway, this was about all I accomplished with the airplane on Sunday, and by the time I'd gotten back to the field, the rain was closing in, and I had to ride my motorcycle home in the rain....
Paul
I have leaned airplane engines many different ways in my years of flying - mostly by ear, pulling the mixture back until the engine gets rough, then smoothing it out a bit (or leaving it a bit rough if I really want to stretch the range, and can live with it!). I used th original primitive analog single cylinder EGT's (which failed all the time in rental planes). I've used multi-cylinder bar-graph displays, both the LED kind and the similar displays on EFIS systems today. But my favorite way to look at EGT's has got to be the "time graph" representation on the GRT EFIS!
Here you can see it in the middle of the display:
This was taken after I had leaned, and the temps had settled down to "steady state". You can see where the temps started out low, then climbed as I leaned, and finally they "knee over" to the peak (or ROP, or LOP - whatever you want) EGT. It's not as pretty as usual - I was scudding along under the clouds at 1,000' in the bumps, and the engine doesn't really lean that nice in the thick air at 75% power. If this had been at altitude, you would have seen the four EGT's lay right on top of each other when the engine gets to the "sweet spot", with the digital temps being clustered within 10 degrees of each other. What has always been of interest to me is how far apart the temps are when the engine is running too rich - the lines are the same shape, but the temperature deltas are large.
To show how the graph works, I shot a little movie that you can find here. It's pretty bumpy, but if you've never seen this work, it will give you the idea.
Maybe it's just the way my brain works, but it is so much easier to see what the temps are doing and how the engine is leaning with the graph rather than bars, where I have to interpret the numbers. I think it is essentially an Analog versus Digital argument - the "analog" graph is easier to understand at a glance. It may work differently for others!
Anyway, this was about all I accomplished with the airplane on Sunday, and by the time I'd gotten back to the field, the rain was closing in, and I had to ride my motorcycle home in the rain....
Paul
