A little perspective on the F-35 mach limits

Lockheed test pilot Billie Flynn is speaking out about the Mach limits placed on the F-35B and C by the Pentagon, and putting things into perspective. On two separate test flights in 2011, both flown by him, aircraft sustained damage during high speed tests. The B model suffered bubbling and blistering of the RAM coating, and the C model suffered thermal damage to the tail boom and horizontal control surfaces.

During the testing of both aircraft, the flights lasted for several hours, with repeated supersonic runs. The B model was flying near its top speed, and maneuvering to the edge of its envelope at the time. The C model would make a supersonic run, which also involved firing a missile, reset and make a second run, before clearing off to the tanker to refuel before doing it again. He said that mission lasted 4-5 hours flying a similar profile the entire flight.

He also said that he doesn't recall seeing any obvious damage to either aircraft in post flight walk arounds.

www.defensenews.com...

a reply to: Zaphod58

Thanks👍

You mentioned earlier that 2 F-35's equals one F-22. I was perplexed but not.

Off subject. But I got up at 5am my dad's time to plant U.S. OF AMERCA Flags at a local cemetery with my dad. It was raining hard. Goal is 3000 graves, then pops said we have to get the others( 1/2 miles by 1/2miles of markers we can find not just those in the veterans portion) resume at 5am sat 23. My points... still can't look into PIA crash or the 2 Eglin crashes. Now this I'M lacking sleep and education.

But please keep posting🤗😊😊

Cords. 40.5414038, -79.9692088

What were those Mach limits?

What G-limits were the aircraft flying under? They weren't flying "slick", they were carrying munitions...

Did they "over-G", or "over-speed"...?

a reply to: madmac5150

On one flight of the B and one of the C the aircraft were flying within both G and Mach limits but still suffered damage. So the program office put limits on how long they can fly above Mach 1.2 in full afterburner. They tried repeatedly to replicate the issue without success.

originally posted by: Zaphod58
a reply to: madmac5150

On one flight of the B and one of the C the aircraft were flying within both G and Mach limits but still suffered damage. So the program office put limits on how long they can fly above Mach 1.2 in full afterburner. They tried repeatedly to replicate the issue without success.

The engineers screwed it up.

The technicians will figure it out.

That's pretty much how it works.

a reply to: madmac5150

Not really a screw up. It happened once, under conditions that you aren't going to replicate, even in combat.

originally posted by: Zaphod58
a reply to: madmac5150

Not really a screw up. It happened once, under conditions that you aren't going to replicate, even in combat.

The technicians, are still the ones that will figure out a fix.

So why putting mach speed limits? F-35 need to fly supersonic in case of intercept or escape.

a reply to: darksidius

They don't spend nearly as much time supersonic as you think.

a reply to: Zaphod58

Question for you zaph. Wouldn't the f35 not want to be supersonic most of the time if its trying to be as sneaky as possible in a contested area playing quarterback? I figure going supersonic would draw lots of attention anyways.

a reply to: BASSPLYR

That's one reason that they won't. Fuel consumption is another.

The f-35 mach limit is much for the skin ? For what I read it is capable to go over mach 1.6, a f-34 A was tested at mach 1.67 and surely can go 1.8 mach, for Block 4 there is a upgrade on F-135 with 10 % more trust is it possible to supercruise ?

a reply to: Zaphod58

If it's something nigh impossible to recreate, even under combat conditions, why the limits? Just kneecapping the F-35 in favor of other birds (ie F-21, F-15X)?

a reply to: cmdrkeenkid

Life cycle. The odds of repeating it are incredibly low, but minimizing them even further ensures the aircraft will make it 40+ years without incurring additional costs for repairs.

originally posted by: BASSPLYR
a reply to: Zaphod58

Question for you zaph. Wouldn't the f35 not want to be supersonic most of the time if its trying to be as sneaky as possible in a contested area playing quarterback? I figure going supersonic would draw lots of attention anyways.

Hey Bass havnt seen you around here in a while, are you still in Australia?

originally posted by: cmdrkeenkid
a reply to: Zaphod58

If it's something nigh impossible to recreate, even under combat conditions, why the limits? Just kneecapping the F-35 in favor of other birds (ie F-21, F-15X)?

Maybe when you go to push the envelope next time beyond these limits?

I am not close to the program but what did the spec say? Capable of sustained supercruise at Mach 1 with the ability to push M1.4?

They pushed to M1.4 and saw some degradation so put the envelope in and said "this is your operational capability" which is more than enough for the current CONOPS.

They may go beyond again to replicate it if they want to test the limit but as its not a problem why bother?

As the article says, they can go as fast and hard as they want regardless of limits in a life or death combat situation so what is the point of stressing a test aircraft when there is so much more testing to do?

Just my 2c

(also, are they actually test aircraft or just borrowed assets from the line - I am assuming they wont see war)?

Some perspective on combat speed. The jet flies in the same regime as the other combat aircraft in its class. It goes super when it needs to and stays subsonic for 98.69% of the other time.

F-35 speed: design wise with thrust available its fast like you would think a fighter should be. Takes a minute to get there but it’s an efficient engine made to fly in that 98.69% regime.

Putting restrictions and limits on G and speed for perspective is like saying “when it’s wet on the road in a hail storm at night with no headlights stay below 90mph in third gear.” In 99.9999999999, repeating of course, of the time the restrictions don’t apply. Fly the jet like a fighter and it is fine.

a reply to: glib2

This is an excellent allusion. But it's also like "If you want your plane to last its full lifetime, follow the instructions. In the case of combat or an emergency, do what you've got to do." In combat and training planes get overgee'd. It's not good, but it happens. Same thing will happen with this.