Blackened From , joined Dec 1969, posts, RR: Posted (12 years 10 months 2 weeks 3 days 18 hours ago) and read 3670 times:
Can anybody please explain how it comes that aircraft need a longer distance for take-off when the airport has a higher altitude or when it's hot?
When it's higher the air is thinner but why is hot air thinner? Doesn't hot air have a higher pressure than cool air?
Peterba69 From United States of America, joined Mar 2002, 70 posts, RR: 0
Reply 2, posted (12 years 10 months 2 weeks 3 days 17 hours ago) and read 3617 times:
Warm air is less dense, thus has fewer molecules/unit, requiring more distance for T/O. Add altitude to it and you come up w/ a combo called density altitude. There's a formula that pilots use to calc. T/O length that factors this, and some A/C might even be temporarily grounded at high alt. airports 'til it cools down. Hope this helps.
Timz From United States of America, joined Sep 1999, 6839 posts, RR: 7
Reply 3, posted (12 years 10 months 2 weeks 3 days 17 hours ago) and read 3602 times:
...about the difference between pressure and density.
You said hotter air is higher pressure, meaning that if you heat up air in a sealed container the pressure increases. Sure enough. But at a given pressure outdoors, hotter air is less dense-- and density is what matters to the pilot.
Av8trxx From United States of America, joined Nov 2001, 657 posts, RR: 6
Reply 6, posted (12 years 10 months 1 week 6 days 19 hours ago) and read 3518 times:
In addition to the posts already offered, this page provides helpful explainations of how air temperature and density affect a aircraft performance. While it refers to props, the many of the same principles apply.