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Old 10-19-2015, 06:19 PM   #1 (permalink)
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flying a phantom boat tail

Professor Alberto Morelli of the Turin Polytechnic Institute is one who has used language which describes a phantom boat tail which trails behind a truncated streamline body of particular tail length.
The first image below is a conventional loop-antenna fairing used by all Allied air forces in WW-II.
The second image is of an airborne radar system fairing,intentionally truncated,but at a sufficient aft-body length to generate,with the airflow,the remainder of the tail.


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Old 10-20-2015, 08:41 AM   #2 (permalink)
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Would it be fair to assume that when the aircraft is banking or there is a side wind, that the truncation doesn't work as effectively as the full form?
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Old 10-20-2015, 08:56 AM   #3 (permalink)
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Airplanes don't see significant side winds unless they are on the ground or the pilot is using rudder.
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Old 10-20-2015, 09:23 AM   #4 (permalink)
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what frank said. Planes have it far better than us ground huggers, they live in a sea of air. sure there are different layers in different directions, hence the turbulence in flight. For the most part it is smooth sailing.
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Old 10-20-2015, 12:13 PM   #5 (permalink)
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It's basically a difference in viscosity: Planes & birds "fly/swim" through air (light & compressible) and submarines & fish "swim/fly" through water (dense & incompressible).
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Old 10-20-2015, 03:57 PM   #6 (permalink)
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I don't have a handy reference, but isn't air basically incompressible until you reach transonic speeds?

Also—supercavitating torpedoes and shark skin.
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Old 10-20-2015, 05:26 PM   #7 (permalink)
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effectively

Quote:
Originally Posted by kach22i View Post
Would it be fair to assume that when the aircraft is banking or there is a side wind, that the truncation doesn't work as effectively as the full form?
*If the pilot is finessing the aileron and rudder controls properly,a banked turn on final approach will have nearly perfect longitudinal flow.
*If you're screaming into turns to burn off airspeed for a short field landing,then yes,the flow is a mess,but you'll have full flaps anyway,and the drag of the avionics pod will be nothing in comparison.
*Side winds will require crabbing,but it takes quite a crosswind to cross-up a plane so much that the tails would get dirty.If it's a problem,then you're probably looking for an alternate airfield.
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Old 10-20-2015, 05:40 PM   #8 (permalink)
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compressibilty/cavitation

Quote:
Originally Posted by freebeard View Post
I don't have a handy reference, but isn't air basically incompressible until you reach transonic speeds?

Also—supercavitating torpedoes and shark skin.
*Yes,air is considered an incompressible fluid at 'low' speed.
*The supercavitating torpedo is riding within a shroud of gas surrounding the body,created by a portion of the rocket's flow,directed forward to discharge nozzles in the nose.It essentially never touches the water.
*The shark skin has water sequestered within the surface matrix,and the outer flow is 'rubbing' against water,rather than a solid surface.
*Penguins carry air,embedded within their feathers to isolate a portion of their surface area from the water.Gentoos are the fastest,with a frontal area based Cd 0.07.
*Russian ice breakers have 'bubblers' which 'lubricate' the interface between the hull and ocean water.Like the Squall rocket-torpedo.

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