KDTWflyer
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Reverse Thrust Induced Turbulence On Tails

Thu Oct 10, 2013 11:42 pm

I got this Gulfstream IV landing in PTK yesterday and noticed the horizontal stabilizer dancing around like crazy (almost like that inflight flutter footage from NASA but less extreme) during the rollout phase on 9R. My only guess is that it is from the reverse thrust jet blast hitting the horizontal stabilizer however I have not seen it before as much as this. Check it out...

http://youtu.be/9RTwfHNDPvI
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goboeing
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RE: Reverse Thrust Induced Turbulence On Tails

Thu Oct 10, 2013 11:49 pm

Yep, lots of bouncing around back there.

I don't have any time in Gulfstreams but when I was on the ERJ, if you put in a good amount of reverse thrust the yoke would shake a lot from the tail buffeting around. On the ERJ, and I'd imagine every other t-tail out there most likely, idle was not enough to do this. Only when the engines were spooled up would it buffet to that extent.
 
ANITIX87
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RE: Reverse Thrust Induced Turbulence On Tails

Fri Oct 11, 2013 2:04 pm

Watch a 747 takeoff from the right angle and you'll see the entire empennage shake like crazy (especially the horizontal stabilizer). That's obviously not reverse thrust, but still cool to see.

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oly720man
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RE: Reverse Thrust Induced Turbulence On Tails

Fri Oct 11, 2013 4:46 pm

The reverse thrust doesn't hit the tailplane directly, it's pointing forwards and up ahead of the tailplane.

But, as the reverse jet spreads and slows down into a very turbulent mess it will move backwards due to the forwards motion of the aircraft. So it's a very disturbed area of flow that causes the vibration of the tailplane, rather than direct impact.
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Jetlagged
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RE: Reverse Thrust Induced Turbulence On Tails

Sun Oct 13, 2013 1:00 am

It's not just the stabiliser bouncing around. The disturbed airflow due to reverse thrust can cause a loss of directional stability.
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zeke
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RE: Reverse Thrust Induced Turbulence On Tails

Sun Oct 13, 2013 1:33 am

Quoting ANITIX87 (Reply 2):

Look at a 777 also.
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wingscrubber
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RE: Reverse Thrust Induced Turbulence On Tails

Sun Oct 13, 2013 2:48 pm

Some nice thrust reverser CFD visualisation here, scroll down to page 15-
https://www.hpcuserforum.com/presentations/October2010China/RecentApplikcationsofCFDtotheDesignofBoeingCommercialTransports.pdf
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