Effect of temperature on Take-off distance

[airsmiles]

Could someone please tell me to what degree varying temperature would have on the take-off distance?

e.g. for a given a/c and with no other varying parameters, what would be the T/O distance at 10, 20 and 30 degrees C ?

Is there an optimal temperature or is it the colder the better (i.e less runway required) ?

Thanks
airsmiles

[df1]

Assuming I understand your question - temperature increase will increase the take-off distance required. This is due to the reduced air density as a result of the higher temperature.

Other factor which increases take-off roll (reduce performance) is humidity! This also has the effect of reducing density. High altitude airports suffer directly from lower densities (density reduces with increase in altitude).

Don't forget engine performance as the engines operate better at lower ambient temps and higher density!

I don't have any specific figures for comparrison, sorry!

[You splitter]

Airsmiles,

We ususally work this out on weight, (which is variable) as opposed to runway length, as generally you have one length of runway to play with.

Every aircraft is differant but in general the more dense the air is the better the take-off and climb performance as it flows over the wing surface. Obviously the warmer the air the less dense the air particles are therefore decreasing lift performance as they flow over the wing. In order to meet the requirements of the runway length and climb to avoid any obstacles the weight of the aircraft may have to be reduced accordingly.

The flap setting also varies the performance.

Some examples for you with Bae146 at LCY using a Flap 24 setting on runway 28.

10 deg c. rtow = 37365 kgs
15 deg c . rtow = 36929 kgs
20 deg c . rtow = 35769 kgs
25 deg c . rtow = 34559 kgs

You can see as the temp increases the reduction in max weight also decreases.
Again there are so many variations of flap settings, tempretures, runway lengths, aircraft performance , obstacles etc. it is impossible just to give a generic answer.

Maybe an expert out there will clarify this for us?

Cheers YS

[Dufwer]

When talking about GA flying, the CAA recommend that when calculating take-off distance that a 10% increase is applied for every 10 degrees C above standard. Not a very scientific method but I'm sure it has enough error margin build in to cover most GA aircraft. Landings calculation use 5% increase per 10 deg C.

D