Lean of peak

Any DA40 related topics

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Lou
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Re: Lean of peak

Post by Lou »

I retract TO flaps 300-400agl after positive rates are confirmed. Then rpm, and fuel pump.

I was a passenger in a Pipistrel Viper last year and the pilot, who is the dealer, had a different technique. He would take off, stay in ground effect and retract flaps. Then the aircraft would accelerate in ground effect before commencing an aggressive climb. It was really fun.
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Hans
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Re: Lean of peak

Post by Hans »

Always use performance chart.....1800...3Kft....21.8MP....burns around 5.0-4.8 per hour....between 95-105 knots....CHT... are around 310 depending upon season...never in a rush
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rwtucker
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Re: Lean of peak

Post by rwtucker »

Hi Hans,

If practical, I like to climb at 100 kts. Doing so helps keep my CHTs below 400 on hot days.

I have never had my prop down to 1800 RPM; 2200 is the lowest speed that seems to work for me.

I have standard injectors and fine-wire plugs. I can fly LOP very smoothly but not at all RPM and MP settings. I love to fly that way when I have the time (which seems almost never). My CHTs drop to the 200/300 border, fuel flow drops into the 6-7 GPH range, and I generally pay only a 15-20 kt. penalty. The engine is also spooky quiet.

I'll take any extra knots you don't give Antoine.
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Hans
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Re: Lean of peak

Post by Hans »

That's great info....will try 2200 with the MP 'by the book" then lean from there.....is this all altitudes ?
Thx
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rwtucker
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Re: Lean of peak

Post by rwtucker »

I don't know anything about low altitudes Hans. The lowest I fly is 7,500 and usually 8,500-11,500. At 7,500 MSL, 2250 at 21-22 MP is an area that you might start with. I often end up with a odd combination of numbers because I find that a difference of 10 or 20 RPM or a fraction of an inch of MP can make a difference in smoothness. I also run a little richer than the leanest I can get away with. It seems less sensitive to minor changes in atmospherics that way.
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Hans
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Re: Lean of peak

Post by Hans »

OK...will do thanks for the great info. love to hear other pilots "idea, or favorite settings"...

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Re: Lean of peak

Post by BlueYonder »

I'm just finishing up my transition training with a Diamond factory-certified CFI, so have factory-fresh recommendations for planes of my vintage (2007/8).

His recommendation is that the prop be pulled back to 2400 before leaving the pattern; and that this should be the default setting for everything not involving pattern work. When in doubt, put it there. If you don't have a good reason to change it, leave it there.

Flaps should come up at about 100' AGL (sometime before reaching the end of a middling-sized runway, in other words). I love the feeling when they come up: suddenly, we're in bat-out-of-hell climb mode, which is a lot of fun.

His recommended lean settings are about 1400 ROP, which typically gives me 9-10gph standard cruise.
The highest art form of all is a human being in control of himself and his airplane in flight, urging the spirit of a machine to match his own. -- Richard Bach
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Colin
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Re: Lean of peak

Post by Colin »

There was a harmonic vibration introduced into the exhaust risers at 2400rpm. It was solved with some additional pieces, I think, but my hand still won't ever put it at 2400. The prop goes from max back to 2350.
Colin Summers, PP Multi-Engine IFR, ~3,000hrs
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BlueYonder
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Re: Lean of peak

Post by BlueYonder »

I'll try it. Thanks.
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Re: Lean of peak

Post by Antoine »

BlueYonder wrote:I'm just finishing up my transition training with a Diamond factory-certified CFI, so have factory-fresh recommendations for planes of my vintage (2007/8).

His recommendation is that the prop be pulled back to 2400 before leaving the pattern; and that this should be the default setting for everything not involving pattern work. When in doubt, put it there. If you don't have a good reason to change it, leave it there.

Flaps should come up at about 100' AGL (sometime before reaching the end of a middling-sized runway, in other words). I love the feeling when they come up: suddenly, we're in bat-out-of-hell climb mode, which is a lot of fun.

His recommended lean settings are about 1400 ROP, which typically gives me 9-10gph standard cruise.
This is quite amazing. I am not a CFI and have no claim to teaching flying, but I do not like the recommendations above.
I would never touch the flaps at 100 feet AGL. In fact I would not change anything to the configuration of an aircraft unless necessary (Go Around) that low. Imagine what can happen: a flap symmetry failure, a bump while you hit the switch and you end up with full flaps and simply a bank induced by reaching for the flap switch. And did I mention engine failure?
Get to 500 feet safely and then start fiddling is my personal rule.

Pulling back to 2400 RPM before the climb is doing it "by the book" - only the old book before the addendum that removes this limitation. It castrates the DA40's climb rate and, as Colin said, puts the engine/prop in an RPM band that I don't like. Is your CFI an engineer or "just" a CFI?

Since this forum is read by many people, I felt that it was necessary to object to the above "factory blessed" ideas. Nothing personal - just wanted to share my experience which is VERY different. Let people choose their comfort zone
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