Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Dave Phillips
#1455686
The MoD operate their Tutors with the engine leaned AT ALL TIMES. When doing power checks you set an RPM/MP and then lean to a predetermined fuel flow. You take-off with the red lever set in that particular position.
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By Paul_Sengupta
FLYER Club Member  FLYER Club Member
#1455688
akg1486 wrote:I was told the rule of thumb to lean for maximum power before takeoff at altitudes of 3,000+ feet. (Temperature comes into play as well, of course, but I can't remember any rule of thumb for that.)


Just use density altitude instead of actual altitude.

There's a thingie on the back of the whizzwheel to work it out! :clown:

But leaning for max power will sort it. You need to use density altitude in runway and climb calculations though.
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By Josh
#1455690
Many of us have flown from Big Bear, which is at 6,700' - they display signs warning you to lean before departure. I just looked at today's conditions - temp/dp 27/-1 and a QNH of 1017 which give a density altitude of 9,500'!!!

It is not something to be messed with, and a typical mountain checkout will cover density altitude performance, increased TAS on takeoff and landing, ridge crossing & ridge lift and engine handling amongst others.

Hot and high is not exclusively a mountain issue - even Limoges which has been discussed elsewhere recently as an enroute stop off is 1,300' and on a hot day could easily get up to a density altitude of 3,500'+

I can't also help but think this links into the discussion on club checkouts elsewhere...
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By Old Pilot
#1455695
It may well do but when you are flying your own aircraft who checks you out?

I did my ppl h in Perth Western Australia and was taught how to drag a R22 off two up on half tanks. Very weird to drag a helicopter on the skids along the ground.
The performance in high temps is terrible but teaches you a few tricks.

Never take the aircraft for granted is the one that has always stuck in my mind.
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By Flintstone
FLYER Club Member  FLYER Club Member
#1455703
Leaning for hot and high is (was) in the Australian syllabus so some parts of the world consider the danger.



As for the mishap forming the basis of this thread, at least the support crew in the chase (lead?) aircraft were okay. :D

I know, I know.
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By Jetblu
#1455706
Old Pilot wrote: I never thought about leaning as it is not part of the training in Europe.



As a result of this thread, I'm guessing that you will now be thanking her for teaching you something. :lol:
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By Waveflyer
#1455707
^
^
^Careful :D

Raduno is at Asiago in northern Italy next month.

Airfield elevation is 3,409 feet so this thread might be a timely reminder.
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By Sir Morley Steven
FLYER Club Member  FLYER Club Member
#1455712
Waveflyer wrote:^
^
^Careful :D

Raduno is at Asiago in northern Italy next month.

Airfield elevation is 3,409 feet so this thread might be a timely reminder.

Indeed. At 35deg the DA there will be over 6000ft. Have a look in your POH at the full throttle power generated at that DA and the resultant rate of climb.
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By MichaelP
FLYER Club Member  FLYER Club Member
#1455726
Mechanics warned me that using the mixture was not doing my engine any good, "leave it alone". So why did the manufacturer put a mixture control there in the first place?

Here it's been 40 degrees C for quite a while, and I lean the mixture for takeoff from the field elevation of just under 1,000 feet.

I once had the choice between a Tiger Moth, a UPF 7, and a Stearman to fly out of a 300 metre strip near Selby.
The film director chose the Stearman.

If I was to choose from these types and many others what I would fly out of Winslow, I would choose the Stearman. At sea level it has a lot of go, and at high density altitudes it would still out perform many of the aeroplane types they fly in and out of Winslow every day.

Regardless of the ins and outs of leaning, we all need discipline in our takeoffs, and a willingness to close the throttle and stop if we do not reach flying speed in a reasonable time and distance.
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By Kittyhawk
FLYER Club Member  FLYER Club Member
#1455728
I did a mountain checkout from Leadville Colorado, in an old 172. Airfield elevation 9927' Hot August day. Calculated DA 14,500'. Runway length 1951m. Lean for best power and keep it down in ground effect using as much of the runway as possible. Interesting...
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By Sam Rutherford
#1455729
Although the conditions were perhaps 'against' a safe departure, she does talk of a loss of power at 50ft - could have been an engine problem?

I lean for best power when hot or high (lesson learned in Kenya).

Kittyhawk mentions staying in ground effect, I actually stay in ground effect on all take-offs for quite a while after the wheels are off the ground so that as I go into the climb I am on or in excess of best climb speed (avoiding a climb out on the front of the stall).
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By MichaelP
FLYER Club Member  FLYER Club Member
#1455732
If at 50 feet there is no runway ahead of you when it's length is as long as Winslow's then there was a problem much earlier in the takeoff.
If the takeoff was from a 2,000 foot strip then I'd agree it would have been unfortunate.

I refer to the Cessna 172 accident here, shown on Youtube
Where the pilot elected to takeoff with full flap.
Even overloaded this Cessna 172F would be airborne in less than half the 900 metres of this strip, 1000 ASL, +38 C.
In this case the flaps were selected full down, 40 degrees... The pilot claimed the engine lost power, and the aeroplane would not climb.

We all make mistakes, and so when an aeroplane fails to perform we should stop and look for whatever the problem might be.

I flew G AROY, and in this aeroplane the propeller was either full fine or full coarse, and it wouldn't operate in between.
Full fine she leapt off the ground with elacrity, zoom zoom :D
Full coarse forget it, the aeroplane will be slow to accelerate, and then the engine will get tired of this and let you down.

Okay, I have only flown the 450 and 220 Stearman biplanes from temperate England, never in the high desert, but I can not imagine why this aeroplane would fail to perform as well as most, and better than many in the situation of a hot and high takeoff.

So like everyone I await the report on the accident, and I can not speculate on the cause, but there is a caution, a lesson for everyone, that having a decision point on your takeoff roll and then when all is wrong at that point, closing the throttle and stopping in a discipline manner will save you and the aeroplane.

We don't always have a satisfactory stop/go distance, sometimes a Go is having 75% of the takeoff speed at the half way point on a strip, and EFATO will be a nuisance...
With 7,000 feet of runway you have plenty of time to decide to abandon a takeoff, and you should not be at only 50feet beyond the end of it... That's reserved for a youtube video of an Ilyusin 76 takeoff :roll: :roll:
By Geronimo
#1455756
Interesting theme of leaning for full power - I thought advice was full rich for full power as the excess fuel helped to cool the agricultural engines we use. Which I would have thought was even more significant in hot and low air density?
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