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Old 20th July 2003 | 04:58
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fobotcso
 
Joined: Jun 2000
Posts: 1,003
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From: Geriatrica, UK
No of course not! But it's a lovley fantasy. Imagine where it might end? Supersonic with the engines at cut-off where the only way to slow down is to start them all up and open up to max contingency....

But seriously, even the heaviest of aircraft can be affected by Wave Lift in the lee of a mountain range in strong winds. I can see the possibility of a short-term wave effect in extreme conditions that would cause an apparent (real, even) increase in energy of a jet airliner. But it can work the other way too.

There was an airfiled called Crosby-on-Eden near Carlisle on the English/Scottish border where there was an RAF Maintenance Unit where they prepared Brigands (I think) for delivery to operational units during WWII.

The Brigand was a pig on two engines let alone one. They lost a lot of them just after take-off either because of real engine failure or practices coupled with a strong Easterly wind and the kind of atmospheric conditions that favoured standing wave. I refer, of course, to a strong down draught that would rob the aircraft of what little energy it had just after take-off. This can arise form an unstable atmospheric layer of 2000-4000ft sandwiched between two more stable layers. (Think of a spring analogy).

And, yes, this can be found at very low levels.

I have flown a Jet Provost in strong North Westerly winds in the lee of the Penines and gained height at constant low power settings and best gliding speed. It helps to have the lenticular cloud to visualise the up and down side of the wave and then you just fly along the up side. I've done in sailplanes too; its a lot easier.

Hope you win your bet?
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