benair
Posts: 7
Joined: Wed Jul 26, 2006 11:27 pm

Typical Flight Data For Long Range Mission

Wed Apr 18, 2007 10:11 pm

Hi everybody,

I am working on a research project for shock control in transonic flight. Currently I am trying to come up with some data about typical flight conditions during long range missions, where wave drag may occur. Important information for me would be how lift coefficient, mach-number, altitude, etc. change during a flight. I figure these information are some way or the other available from flight plans, however, I can't find any source to get a representative number of flight plans from.

Is there anyone out there to give me any tips on how to find these kind of data? Or are there any long range pilots that can give me some estimates at least on typical changes in cL and mach-number during a mission (preferably for A340 but any other type is welcome as well)?

Thanks for the help,
benair
 
oly720man
Posts: 5743
Joined: Fri May 21, 2004 7:13 am

RE: Typical Flight Data For Long Range Mission

Fri Apr 20, 2007 1:59 am

Have you tried asking the airlines, eg LH, for such data?

During a flight, the cruise Mach number will hardly change for reasons of separation, especially on busy routes such as transatlantic.

Lift coefficient at cruise you may be able to make some sort of assessment from weight and fuel and wing area. In a long haul flight you may find that as fuel is used, higher cruise altitudes may be requested.

I don't know what the lift curve slope for the A340 is, but from here

http://www.aa.washington.edu/courses...01/WebTools/Lift-Curve-Slope.shtml

a high aspect ratio wing at around 30 deg sweep has dCl/da of around 4.7 (0.75*2*pi)
or 0.08 per degree

From the A340 specs, with mass of 200000kg, wing area 363m2, M0.84 at 11000m, V = 248m/s.

This gives lift coeffiicent of around 0.484

With a mass of 60% this at the end of the cruise the lift coeffiicent will be 0.290

the change of 0.484 to 0.290 is around 0.2 in Cl which is 2.5deg in incidence.

Lots of approximations, but probably not too far from the real numbers.
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