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Could anyone tell me why the left aileron and horizontal stabilizer in this image appear a whitish color?

F-35 Lightning II ninth flight - March 13th, 2007

Flight #18 - A good top profile view.

Flight #11 - Another afterburner take off. Note the white paint (port wing) which is used is for fuel dump testing. The fuel dump port is under the port wing and the special paint turns red/pink when exposed to fuel.

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Elite 1K Joined: Aug 19, 2004 Posts: 1092

It looks like the paint has been removed. Doesn't it? Smile

is it for testing photography so they can rapidly tell orientation?

I think it has to do with fuel dump testing since that's the wing the dump is located in.

F-35 looks sweet...

If it's fuel dumping, why the stab also (if they think the fuel dump will impinge on the stab, one would think they would paint the leading edge, not the trailing edge.

The small amount of paint on the stab doesn't look like it would help much for orientation and can't imagine it would be worth the cost and hassle. The mass of the paint is usually accounted for in flutter calculations so I doubt there is NO paint there...it is most likely painted but a different color.

Very interesting...my interest is piqued!

Also, what is that protrusion/intake looking thing on the port side of the F-35 next to the left vertical tail (between the engine and the tail)?

Elite 1K Joined: Aug 01, 2006 Posts: 1003 Status: Offline

PhillyGuy wrote:

Also, what is that protrusion/intake looking thing on the port side of the F-35 next to the left vertical tail (between the engine and the tail)?

That is the APU - Auxiliary Power Unit - exhaust. A mini gas turbine generator that provides electrical power on the ground when the main engine is not idling or in-flight in case of an engine failure. You'll find similar devices in the tail cones of Boeing and Airbus airliners. They eliminate the dependency on ground power hookups.

Enthusiast Joined: Sep 07, 2006 Posts: 30 Status: Offline

PhillyGuy wrote:

Could anyone tell me why the left aileron and horizontal stabilizer in this image appear a whitish color?

If you go back through the test flights, you'll see the shape of the white area changes. One version is a big, swooping scimitar arc.

-- Shaken - out --

dwightlooi wrote:

That is the APU - Auxiliary Power Unit - exhaust. A mini gas turbine generator that provides electrical power on the ground when the main engine is not idling or in-flight in case of an engine failure. You'll find similar devices in the tail cones of Boeing and Airbus airliners. They eliminate the dependency on ground power hookups.

More precisely, it is the PTMS (Power & Thermal Management System) exhaust. The PTMS provides APU, ECS and RAT functionality, all in one package.

And yes, the white paint is for fuel dump testing. The fuel dump port is under the port wing and the paint turns red/pink when exposed to fuel.

Jon Beesley said the color is a light pink and he was quite embarrased to fly the airplane with such colors. Pink is visually the best for low observability...I wonder why we don't see more pink planes?!

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F-35 image question - Left aileron and horizontal stabilizer