PODcast - Parts I & II: F-35 in the Crossfire [Sprey/Berke]

Discuss the F-35 Lightning II
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Unread post28 Aug 2017, 02:42

Salute!

We routinely pulled well above the limits in the Dragonfly. Then had to face the music after landing with the upper wing surface all "rippled". It was easy due to the straight wing and speeds we used to deliver ord. Snatch back and then ease off when realizing what you had done. Our eventual cracked spars came from taxiing with lottsa weight outboard of the gear - tension on the spar and not compression.

Our early opinions on the "help" mod to the Viper FLCS was "hell no". The question was what the criteria would be for Hal to takeover. I personally sat in the back seat for a G-loc by student studly, and the deal was "onset" and failure to clench at the beginning of the pull while looking over the shoulder. I still have reservations about too much "protection", but whatthehell.

I would prefer a system using actual radar and inertial flight path versus a database that may be corrupt or just plain wrong. But what would I know.

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tincansailor

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Unread post28 Aug 2017, 05:35

If you are in a "save your life" dog-fight heading straight for the ground with a bogie/missile on your tail, auto computer limits can be deadly. In fighters of old, if you needed to pull 14 G's to save your butt, you pulled them and landed, and sent the airframe to the boneyard, assuming the wings hadn't fallen off. Auto fly by wire denies you that flexibility. If auto-GCAS calculates against a 5G pull out, you lose the 14Gs against a missile life saving option.



Can a human being really take 14G's? You always hear 9G's is the human max, but can a pilot in top shape do 14G's for more then 2 or 3 seconds without blacking out? For a 175lbs guy that's like a compact sedan sitting on your chest. Amazing.
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Unread post28 Aug 2017, 06:57

tincansailor wrote:...Can a human being really take 14G's? ....


In fairness that's a cobweb covered memory of a second hand account, but the number was 14, and I recall the aircraft did go to the boneyard IF I remember correctly. I'm sure it was an instantaneous pull for less than a second. Yank and release. not sure about the onset rate, But I'd imagine it came after being in a high G pull already underway, such as pressing at 7 and then yanked a bit more, said, "oops,"(or blacked/greyed out) and released. Again other than standard T-38 stuff, I never pulled anything near that high G range, certainly not in the KC-Q, although that airframe (707) was way overbuilt, (after the Electra crashes Boeing designers got very nervous with the jets) so it probably could have pulled a ton with a light load. My reports on fighters are second hand. (and ancient memories).

The point is, when to over G, or when to initiate ground avoidance, and how, and what options are available for such a thing is a fine art, and not a science lightly given to be imposed by "HAL." That's true of F-16's at 9Gs as much as anecdotal 14Gs. I don't expect them to whimsically impose A-GCAS in the F-35 without some serious testing and discussion.

But once that's done, I would assert that HAL can do whatever you ask him to do, and the F-35 systems have the ability to be so programmed today. (once the parameters are decided) Clearly the stories of the effort/success with the F-16s shows a strong desire to look at it by many.

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Unread post28 Aug 2017, 08:23

tincansailor wrote:Can a human being really take 14G's? You always hear 9G's is the human max, but can a pilot in top shape do 14G's for more then 2 or 3 seconds without blacking out? For a 175lbs guy that's like a compact sedan sitting on your chest. Amazing.

Dunno about 14G, but here's a young USN Ensign holding 8Gs for 30 seconds:

https://www.youtube.com/watch?v=UyzqxDbYbhQ
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Unread post28 Aug 2017, 13:12

tincansailor wrote:Can a human being really take 14G's? You always hear 9G's is the human max, but can a pilot in top shape do 14G's for more then 2 or 3 seconds without blacking out? For a 175lbs guy that's like a compact sedan sitting on your chest. Amazing.


Well, from a "can a human survive" point of view, a lot more than 14g...

https://en.wikipedia.org/wiki/John_Stap ... celeration
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Unread post28 Aug 2017, 14:40

Can every human survive it though - or is it practical or realistic in every situation? - someone thinks it isn't.

Can you fly, concentrate, or even look around at 9G or above??



The most experienced pilot on the Osirak raid in 82 (Spector) blacked out on the pull to the target (should have been well under 7G) - and he was the only pilot to miss the actual target. He stated it may have been due to some asthma drugs he had been taking (fit to fly?)

Apparently modern G suits are supposed to help more with 9G loads these days.

A G override on the F-35 seems a good idea for some emergency situations.

Here is some poor sod going for 12Gs - watch to the end :D .

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Unread post28 Aug 2017, 17:19

tincansailor wrote:Can a human being really take 14G's? ...Amazing.


NASA lists 17Gs as tolerable by untrained persons for a short time (and measured onset?) without damage. I suspect that's not seated (at any angle) but on your back, as in rocket sled accelerations.
https://ntrs.nasa.gov/archive/nasa/casi ... 223621.pdf

I like that 12 G video though. And I do know that F-15 pilots have moved the needle to 10Gs if no other reason than to tweak the 9G F-16 guys. That's probably one reason, some of the older Eagles are starting to fall apart. :roll: :wink:
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Unread post28 Aug 2017, 19:17

blindpilot wrote:
tincansailor wrote:Can a human being really take 14G's? ...Amazing.


NASA lists 17Gs as tolerable by untrained persons for a short time (and measured onset?) without damage. I suspect that's not seated (at any angle) but on your back, as in rocket sled accelerations.
https://ntrs.nasa.gov/archive/nasa/casi ... 223621.pdf

I like that 12 G video though. And I do know that F-15 pilots have moved the needle to 10Gs if no other reason than to tweak the 9G F-16 guys. That's probably one reason, some of the older Eagles are starting to fall apart. :roll: :wink:
FWIW,
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Marty (Rafale Solo Display) claims to hit 10 or more Gs every presentation.
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Unread post28 Aug 2017, 22:09

blindpilot wrote:
I like that 12 G video though. And I do know that F-15 pilots have moved the needle to 10Gs if no other reason than to tweak the 9G F-16 guys. That's probably one reason, some of the older Eagles are starting to fall apart.
FWIW,
BP


Although the F-15 breaking apart looks impressive in the recreation - what is more impressive for me is the far less over G events on the F-16 that allows it to still provide value to the US tax payer and still kick the F-15s A :D

Is it known how many F-16s went in because of this? (out of 328 destroyed to FY15) - you would have to also be going some knots at SL to hit that level of G.
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Unread post28 Aug 2017, 22:17

basher54321 wrote:
blindpilot wrote:... That's probably one reason, some of the older Eagles are starting to fall apart.
FWIW,
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Although the F-15 breaking apart looks impressive in the recreation - what is more impressive for me is the far less over G events on the F-16 that allows it to still provide value to the US tax payer and still kick the F-15s A :D


And that's the discussion in a nutshell!

F-16's still flying and pulling 9Gs and at least 4 valuable pilots still alive. If well designed, Billy seems to think the cost (restriction) is minimal for that significant benefit.

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