Runway slope.

[jkaduk]

Does anyone have a rule of thumb on increasing takeoff distance when a known slope exists? How is the percent figure arrived at? I looked at an airport that has a 1% rise, but I couldn't get that number with the runway elevation figures I had.
Thanks

 

[poadeleted20]

Does anyone have a rule of thumb on increasing takeoff distance when a known slope exists?

There isn't one, as it depends on thrust/weight ratio, parasite drag, and a few other aircraft-specific figures.

How is the percent figure arrived at?

Rise/drop divided by length (times 100 to get %). E.g., 40 foot rise over 8000 feet would be 0.5% upslope.

 

[bbchien]

Does anyone have a rule of thumb on increasing takeoff distance when a known slope exists? How is the percent figure arrived at? I looked at an airport that has a 1% rise, but I couldn't get that number with the runway elevation figures I had.
Thanks

John, to be even more concrete than the perfesser, at higher density altitudes the effect will be much greater, as "extra" horsepower will be a much small portion of the total given the continued bite of the drag, the work of pushig the a/c uphill, etc. So this is left to the realm of the test pilot.

The only test pilot work I've ever done was on a 10,000 foot runway doing go/stop (at Vysse) and go/go at Vysse in an aircraft for which 5000 feet is usualy (NOT ALWAYS!) enough.

Bruce