mawingho
Topic Author
Posts: 41
Joined: Sun Jul 22, 2012 4:23 pm

Head Wind Component And Climb Performance

Sat Sep 22, 2012 1:21 pm

When the wind gradient is such that headwind component is decreasing with height, climb performance will be reduced. Why this is true?
 
Mir
Posts: 19167
Joined: Mon Jan 05, 2004 3:55 am

RE: Head Wind Component And Climb Performance

Sat Sep 22, 2012 4:22 pm

Quoting mawingho (Thread starter):
When the wind gradient is such that headwind component is decreasing with height, climb performance will be reduced. Why this is true?

A headwind helps climb performance by slowing the groundspeed so that the angle of climb is steeper. If the headwind reduces as you climb higher, then the benefit you get from it will be reduced as well.

Note that any headwind is better than none. So even if you take off with a 20 knot headwind and it slows to 5 knots as you climb, that's still better for climb performance than taking off with no headwind at all. What the real danger is here is thinking that you can achieve a certain climb gradient because you have a certain amount of headwind, and then finding out once you climb a bit that you no longer have that headwind, and thus are unable to maintain that climb gradient.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
FredT
Posts: 2166
Joined: Thu Feb 07, 2002 9:51 pm

RE: Head Wind Component And Climb Performance

Mon Sep 24, 2012 4:42 pm

A headwind component means that you are going slower over the ground.

If the headwind component reduces, your airspeed decreases. To maintain airspeed, you have to accelerate.

You use thrust for acceleration and for climb rate. More acceleration = less climb rate.

That's why you always do two climbs when doing climb performance testing, the second one along the same track as the first one but on the opposite (reciprocal) heading. With those two sets of data, you can eliminate most of the effects of any wind gradients (i e wind changes with altitude) encountered. With just the one climb, you will have no way of deducing whether any perceived climb rate deviations were due to wind or due to the actual performance of the aircraft. Been there, done that, been saved by having the reciprocal run data. The effect of a wind gradient can be very significant.
I thought I was doing good trying to avoid those airport hotels... and look at me now.

Who is online

Users browsing this forum: Florianopolis, flyoregon and 2 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos