kiwiflyer1 From New Zealand, joined May 2010, 13 posts, RR: 0 Posted (3 years 11 months 2 weeks 4 days 21 hours ago) and read 5475 times:
Hi, just a couple of questions regarding take-off requirements:
I'm reading through a performance book published in Aussie
The ASDA is stated that it must be the higher of:
- The distance required to accelerate to Vef, continue to accelerate to V1 + 2 seconds, then abort the T.O. ; or
- The distance required to accelerate to V1 + 2 seconds, then abort the T.O. with both engines operating.
There is also a requirement for this to be demonstrated without use of reverse thrust, or if using reverse thrust, without brakes.
Is there any situation where the ASDR with both engines operating will actually be less than the ASDR with an engine failure? Since there will be more acceleration, and more idle thrust to brake against surely it must be longer.
The only situation I can think or is if the aircraft demonstrated the RTO with reverse thrust rather than brakes?
The other problem is very similar, it states the TODR is the greatest of:
- The distance to accelerate to V2 and attain 35ft, after recognition of an engine failure at V1; or
- The distance to accelerate to V2 and attain 35ft, with both engines operating, multiplied by a factor of 1.15
This one I would assume that the T.O. with two engines will always require less distance than with the engine failure?
However with the correction factor of 1.15 does this make the TODR with both engines the longer one?
If it can be either then what sort of variables are we looking at to make it go one way or another?
For safe operation, ASDR & TODR must be less than ASDA & TODA (otherwise you run the risk of going off the end of the runway). ASDA & TODA can be different due to the presence of clearways and stopways.
dispatchguy From United States of America, joined Jan 2006, 1249 posts, RR: 2
Reply 3, posted (3 years 11 months 2 weeks 3 days 2 hours ago) and read 5242 times:
Google "Getting to Grips with Aircraft Performance" It is an Airbus document which describes in somewhat painful detail all the intricacies with basic transport category aircraft performance.
You also might be able to find the Boeing document called "Jet Transport Performance Methods", which is the Boeing document for the same thing. Personally, I like the Boeing document better. It's about twice as thick (its page count is well over 700 pages), but it starts with the physics behind speed, inertia, flow of a compressible fluid, etc., before it gets to the nitty gritty about aircraft aerodynamics and performance.
However, reading either document will give you a very well grounded education in transport category aircraft flight performance. The Boeing document assumes you're fairly comfortable with some elementary calculus.