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Photo: F-35 Jet Blast Deflector Testing

By sciencepunk on July 12, 2011.

From Lockheed Martin, a shot of an F-35 (the US stealth-capacity joint strike fighter) torching a blast deflector. I'd love to know what causes those bands in the exhaust flare. Also, check out the badass fireman in the foreground!

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From source:

LAKEHURST, N.J., July 7th, 2011 -- F-35C Lightning II carrier variant aircraft CF-2 is performing Jet Blast Deflector (JBD) tests at Joint Base McGuire-Dix-Lakehurst in New Jersey. The JBD, located behind the catapults aboard aircraft carriers, deflects high energy exhaust from the engine to prevent damage and injury to other aircraft and personnel located in close proximity. JBD testing is one portion of the tests required to ensure the F-35C is compatible aboard the aircraft carrier. Testing continues with varying distances between the aircraft and JBD, and at power settings up to and including maximum afterburner power. CF-2 arrived at Lakehurst on June 25 for JBD tests. (Lockheed Martin photo by Andy Wolfe)

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I'd love to know what causes those bands in the exhaust flare.

Mach diamonds?

By Andrew G. (not verified) on 12 Jul 2011 #permalink

Those are pressure cones as the exhaust leaves the nozzle. Very common. And having ground crew on site is pretty much SOP for any type of ground run testing; they can see parts of the plane that my be hidden from the cockpit.

Yup, those are mach diamonds. Best page I've seen about it http://www.allstar.fiu.edu/aero/rocket3.htm In short, the supersonic flow at the nozzle sets up shock waves that bounce off the inside of the exhaust boundary, giving areas of compressed gas, and also shaping the exhaust plume.

By Robert S. (not verified) on 12 Jul 2011 #permalink

Yes, even if I've always heard the terms "shock diamonds" instead of "mach diamonds", the concept is the same.

any idea if that is a real guy or a dummy set up to find the effects on a real guy working out on the deck?i notice the green shirt is the same as i see on the TV programs about carriers.