Single engine drift down altitude in a part 25 turbojet
Thread Starter
Single engine drift down altitude in a part 25 turbojet
Funny the discussions that come up when passing time in cruise.
Other guy contends that an aircraft experiencing an engine failure below the drift down altitude for that weight should be able to climb to that altitude, all other things equal. I on the other hand think the testing criteria is so specific to drift down that you can’t make that assumption.
Anyone have something other than opinion on the topic?
Other guy contends that an aircraft experiencing an engine failure below the drift down altitude for that weight should be able to climb to that altitude, all other things equal. I on the other hand think the testing criteria is so specific to drift down that you can’t make that assumption.
Anyone have something other than opinion on the topic?
Only half a speed-brake
One of the OEI "strategies" Airbus provides in their documentation to operators ends with a climb at min-clean speed + MCT as the weight reduction would allow.
For what that's worth, FCOM PER-OEI-GEN: Strategy
For what that's worth, FCOM PER-OEI-GEN: Strategy
I think it is fair to question the assumption - in the real world with a real-world airframe. "Not all questions can be answered - but all answers can be questioned!"
Theory would say that if you can just barely maintain level flight at altitude X at weight Y and at VYSE, then you must descend if higher than X - and can climb to X (eventually) holding VYSE, with climb rate decaying to zero just as you reach X, even assuming no fuel burn and weight decrease. (Zeno and his Paradox might disagree).
Consider the very specific middle case: if you are climbing normally, and just happen to reach the SEDDA for weight Y when you happen to be exactly at weight Y - and also happen to lose an engine at that instant (just your lucky day!), presumably you should be able to immediately level off, acquire VYSE and hold that altitude. If you bobble the level-off and end up 10 or 50 or 100 feet low, then can you recover that small loss of altitude with a VYSE climb?
The flaw in the ointment is that weight is never "equal" from one second to the next, unless one can rig a test flight with constant aerial refueling to keep weight constant over time. Thus there has probably been very little experimental confirmation.
I'll concede that thought-experiments are more or less "glorified opinion" and look forward to further responses.
Theory would say that if you can just barely maintain level flight at altitude X at weight Y and at VYSE, then you must descend if higher than X - and can climb to X (eventually) holding VYSE, with climb rate decaying to zero just as you reach X, even assuming no fuel burn and weight decrease. (Zeno and his Paradox might disagree).
Consider the very specific middle case: if you are climbing normally, and just happen to reach the SEDDA for weight Y when you happen to be exactly at weight Y - and also happen to lose an engine at that instant (just your lucky day!), presumably you should be able to immediately level off, acquire VYSE and hold that altitude. If you bobble the level-off and end up 10 or 50 or 100 feet low, then can you recover that small loss of altitude with a VYSE climb?
The flaw in the ointment is that weight is never "equal" from one second to the next, unless one can rig a test flight with constant aerial refueling to keep weight constant over time. Thus there has probably been very little experimental confirmation.
I'll concede that thought-experiments are more or less "glorified opinion" and look forward to further responses.
