You make a good point, Ken. I had never thought about tire speed. You
certainly don't want to blow one at take-off speed!
Tullahoma, TN USA
On 4/20/2017 2:59 PM, Ken Norton wrote:
Are you telling me that airlines routinely operate at or very near maximum
gross weight? So close to the dege that a slight change in winds/weather
could screw up everything? Is that safe and responsible flight?
But it's not as bad as what you make it sound like. That's why they do
all the calculations. And commercial aircraft operations have all
sorts of safety margins built in.
Figure a commonly used jet, the CRJ700. At maximum take off weight, it
needs a 5000 foot runway at sea level and zero wind. But crank the
temperature up to 90 degrees F and the density altitude is now 2500
feet. Instead of a 5000 foot runway, you now need more than 6000 feet.
If you are in Denver International Airport, with about a 5400
elevation, a hot summer day can give you a density altitude in excess
of 9000 feet. The problem with high altitude operations kick in with
not only length of runway and climb-rate issues, but maximum
tire-speed. You need to be going faster over the ground to achieve
lift-off speeds. Take off rolls get much longer and faster.
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