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Aviation maths for Pro !!
I'm trying to find out a formulae regarding the gap between Takeoff
Distances by POH and real-life measures. I did the maths for wind, temperature, pressure altitude, runway slope, weight, etc. It's quite detailled and effective... But... The only calculation I don't know how to "translate" is the difference, in feet, between the POH speed and the speed I did during the test. For example: If my airplane took off at 1050 feet on the initial roll, at 62 knots, how many feet will I need if left the runway at 56 kts ? POH states it requires only 699 feet at 56kts for the same factors (temp, press, etc)! Thank you Paul |
#2
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Aviation maths for Pro !!
On Feb 13, 7:23*am, "Paul" wrote:
I'm trying to find out a formulae regarding the gap between Takeoff Distances by POH and real-life measures. I did the maths for wind, temperature, pressure altitude, runway slope, weight, etc. It's quite detailled and effective... But... The only calculation I don't know how to "translate" is the difference, in feet, between the POH speed and the speed I did during the test. For example: If my airplane took off at 1050 feet on the initial roll, at 62 knots, how many feet will I need if left the runway at 56 kts ? POH states it requires only 699 feet at 56kts for the same factors (temp, press, etc)! I think most of the POH takeoff figures are not theoretical calculations but the results of actual tests. As such they are affected by factors outside aerodynamics -runway surface roughness, tyre performance and pilot skill being factors in rolling distance. In other words I don't think a simple equation will give you the "right" answer. For a first order approximation consider kinetic energy build up. Cheers |
#3
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Aviation maths for Pro !!
On Feb 13, 5:23*am, "Paul" wrote:
I'm trying to find out a formulae regarding the gap between Takeoff Distances by POH and real-life measures. I did the maths for wind, temperature, pressure altitude, runway slope, weight, etc. It's quite detailled and effective... But... The only calculation I don't know how to "translate" is the difference, in feet, between the POH speed and the speed I did during the test. For example: If my airplane took off at 1050 feet on the initial roll, at 62 knots, how many feet will I need if left the runway at 56 kts ? POH states it requires only 699 feet at 56kts for the same factors (temp, press, etc)! I think you will struggle to find a simple calculation ( or a difficult one for that matter) . why dont you just try testing your takeoff distance at the same speed as the POH reccomends? May I ask what aircraft you are flying? and what did you find with your mathematical studies, and did you read my earlier thread on "Confusion with Cessna take off distance " where I found that after converting pressure ht and temperature to density altitude that there was still a temperature effect on the take off distance required. I would be interested to know if you saw something similar wtih your data?. Terry PPL Downunder |
#4
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Aviation maths for Pro !!
On 12 Feb, 18:23, "Paul" wrote:
I'm trying to find out a formulae regarding the gap between Takeoff Distances by POH and real-life measures. I did the maths for wind, temperature, pressure altitude, runway slope, weight, etc. It's quite detailled and effective... But... The only calculation I don't know how to "translate" is the difference, in feet, between the POH speed and the speed I did during the test. For example: If my airplane took off at 1050 feet on the initial roll, at 62 knots, how many feet will I need if left the runway at 56 kts ? POH states it requires only 699 feet at 56kts for the same factors (temp, press, etc)! I've got a couple at home and I'll check for you when I get there, but like I told you before, it all depends on the approach the engineer takes and you're not going to get any real precision out of them |
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