It's actually an interesting question, if you take a look at airbus' published INDICATED Vr and V2 speeds they decrease as temp increases but you're being fooled:
E.g.
This is directly out of the airbus A320 T/O quick reference charts:
As an example for a Config 1+F T/O from a 3000m runway @ PA:0ft:
@-20 degrees: Vr: 162KIAS (KTAS:152) V2:164KIAS (KTAS:154)
@ 50 degrees: Vr: 150KIAS (KTAS:159) V2: 152KIAS (KTAS:161)
So the Vr and V2 INDICATED speeds (the ones published on the chart) DECREASE as temperature increases but when you convert them to TAS you'll find the opposite: the TRUE speed INCREASE as temp increase.
Don't let the indicated temperatures fool you, the aircraft needs a higher TAS through the air to fly in warmer air.
Last edited by Airmann; 31st May 2012 at 11:05.