Article

2019-06-13 Science & Technology

Supersonic speeds could cause big problems for the F-35′s (and Chevy Silverado's) stealth coating

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Posted by Besoeker 2019-06-13 02:24|| || Front Page|| [2 views ] Top

#1 The problem, of course is the coating, but the story would be it would work just fine on anything but an F-35.

Posted by M. Murcek 2019-06-13 07:02|| 2019-06-13 07:02|| Front Page Top

#2 Likely not the coating but airframe skin vibration at speed. That would impact the external sensors as well.

Why altitude? Apparently air density at lower altitudes dampens the vibration.

Posted by Skidmark 2019-06-13 09:10|| 2019-06-13 09:10|| Front Page Top

#3 The stealth F150 doesn't manifest the problem because of it's constrained operating velocity.

Posted by Skidmark 2019-06-13 09:12|| 2019-06-13 09:12|| Front Page Top

#4 Hey, now!

Posted by Frank G 2019-06-13 09:38|| 2019-06-13 09:38|| Front Page Top

#5 Why altitude?

My SWAG: Less atmo pressure so the afterburner cone spreads out faster. On the B, the shorter nozzle (vs A) allows the afterburner stream to overheat/overpressure the coating. On the C, the horizontal tail is longer (vs A) resulting the effect as the B.

The Defense Department does not intend to field a fix for the problem
It only showed one time on the B & C during testing and has not been duplicated but afterburner restrictions remain for now.

https://www.defensenews.com/air/2019/06/12/supersonic-speeds-could-cause-big-problems-for-the-f-35s-stealth-coating/

Vice Adm. Mat Winter, who leads the F-35 program on behalf of the Pentagon, told Defense News that the department has taken steps to mitigate the problem with an improved spray-on coating, but added that the government will not completely fix it — instead accepting additional risk.

As justification for the decision, Winter noted that the issue was documented while the jet was flying at the very edge of its flight envelope. He also said the phenomenon only occurred once for both the B and C models, despite numerous attempts to replicate the conditions that caused the problem.

“How often do we expect something like that to occur?” he said. “It's very, very small.”

Greg Ulmer, Lockheed Martin’s F-35 program head, said there have been no cases of this problem occurring in the operational fleet and that incidents have been limited to the “highest extremes of flight testing conditions that are unlikely replicated in operational scenarios.”

Posted by Gloger Spawn of the Gepids2733 2019-06-13 10:20|| 2019-06-13 10:20|| Front Page Top

#6 The stealth F150 doesn't manifest the problem because of it's constrained operating velocity.

HA! I had a used 1983 way back when that I beat the rest of the way to death on NJ fire roads. Thanks for the flashback, I haven't thought about that rattle trap in years.

Posted by One Eyed Tsar 2019-06-13 10:24|| 2019-06-13 10:24|| Front Page Top

#7 The F150 might have that problem but not the Tesla traveling much much faster.

Posted by 3dc 2019-06-13 12:23|| 2019-06-13 12:23|| Front Page Top

#8 The stealth F150 doesn't manifest the problem because of it's constrained operating velocity.

Rumor has it that Ford has hacked the engine software to keep the top speed under Mach 1. Something to do with EPA fleet mileage standards.

Posted by SteveS 2019-06-13 12:48|| 2019-06-13 12:48|| Front Page Top

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