F-35A maximum G rating lower than 5?!

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ryokenmk

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Unread post18 Mar 2014, 05:03

http://www.flightglobal.com/news/articl ... al-381683/

Just read this. Somebody please tell me that's bull.
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mk82

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Unread post18 Mar 2014, 05:16

Its definitely bullshit :D. These figures are useless if you do not know the specific circumstances (e.g. airspeed, altitude,aircraft weight etc) involved in obtaining these G "readings". The F35A is definitely a 9G capable aircraft.
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ryokenmk

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Unread post18 Mar 2014, 05:42

mk82 wrote:Its definitely bullshit :D. These figures are useless if you do not know the specific circumstances (e.g. airspeed, altitude,aircraft weight etc) involved in obtaining these G "readings". The F35A is definitely a 9G capable aircraft.



I believe you, but I'd like some sources to use as ammunition if you don't mind :)
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exosphere

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Unread post18 Mar 2014, 06:13

mk82 wrote:Its definitely bullshit :D. These figures are useless if you do not know the specific circumstances (e.g. airspeed, altitude,aircraft weight etc) involved in obtaining these G "readings". The F35A is definitely a 9G capable aircraft.


I believe they're talking about sustained gee maneuvering. The F-35A is a nine-gee capable aircraft, though -- it is nine-gee capable in an instantaneous turn. The C is limited to seven and a half gees, and the B is limited to seven gees, just like the Hornet and Harrier they are replacing.

Like you said, though, those limits are meaningless unless you know the exact parameters under which they are applicable. I believe smsgtmac has an excellent piece about that on his site (Elements of Power).

Although the F-35A/B/C instantaneous gee limits are identical to the aircraft they are replacing, the JSF has one major advantage -- the F-35 variants can pull their maximum gee loadings with combat loads. The F-16 might be able to pull nine gees at an airshow or with a light load, but I seriously doubt it could do so with two 2k bombs, two AMRAAMs, a Sniper pod, and a full tank of gas. I seriously doubt it could accelerate to more than mach 1.6 or fly at its absolute ceiling with that load either, which tackles two other complaints people have about the F-35A vs the plane it is replacing.

I think much of the argument that the F-35 is in maneuverable comes from a failure to understand the difference between an airshow loadout and a combat loadout. Without knowing the difference, people invariably make apples to oranges comparisons.

Regarding transonic acceleration -- I might be wrong, but I don't think most dogfights involve accelerating to supersonic speeds. I believe they're mostly subsonic. Gums would probably know more about that, though.
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zero-one

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Unread post18 Mar 2014, 09:13

Here's my take on the reduced spec fiasco.

Regarding Turning, We know that in Air-air configuration the F-35 can turn better than the Vipper.
As seen here: viewtopic.php?t=24472

We know that at subsonic speeds, it can accelerate just as well as a Viper to which really good for air-air combat.

So just by those two alone, the fear that the F-35 might be outmaneuvered by a horde of Flankers and Fulcrums should go all out the window.

The F-35 can hold its own in a gun fight if it ever came to that.

But on the other hand the reduced spec also tells me that for a certain particular airspeed, altitude and loadout where the
F-35A was suposed to hit 5.3Gs,
it didn't quite make it.
dont know if it was close or way off,
but it tells me that for that particular configuration the F-35 did not make it.

How much will this affect the F-35, well I don't know, Sustaining 4.6Gs is about the same for an F-15 with a combat load, and new more powerful engines will eventually be feilded on the F-35 increasing sustained G rates, so I wouldn't be too worried.
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cantaz

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Unread post18 Mar 2014, 12:20

Everything you want to know, I'm surprised it was not the first response: http://elementsofpower.blogspot.ca/2013 ... -spec.html
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cola

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Unread post18 Mar 2014, 23:59

exosphere wrote:Although the F-35A/B/C instantaneous gee limits are identical to the aircraft they are replacing, the JSF has one major advantage -- the F-35 variants can pull their maximum gee loadings with combat loads.

Of course it can't...it can't even pull 9g with its fuel tanks full and AIMs only, let alone in 'combat load' (assuming non-AA weaponry, like bombs and such).
Cheers, Cola
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archeman

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Unread post19 Mar 2014, 00:29

cola wrote:
exosphere wrote:Although the F-35A/B/C instantaneous gee limits are identical to the aircraft they are replacing, the JSF has one major advantage -- the F-35 variants can pull their maximum gee loadings with combat loads.

Of course it can't...it can't even pull 9g with its fuel tanks full and AIMs only, let alone in 'combat load' (assuming non-AA weaponry, like bombs and such).


But keep in mind, the F-35 has a crazy-high fuel % when just topped off. Far greater than most other combat aircraft w/out external tanks.
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Unread post19 Mar 2014, 00:35

Somebody might know more than 'cola' ["...it can't even pull 9g with its fuel tanks full and AIMs only..."] here:
The F-35’s Race Against Time Nov 2012 John A. Tirpak Executive Editor
"...Lockheed Martin Vice President Stephen O’Bryan, the company’s point man for F-35 affairs, declared that the fighter meets requirements. A former Navy F/A-18 Hornet pilot, O’Bryan said...

...Stealth also permits (and requires) internal fuel and weapons carriage. The Air Force F-35 variant, fully loaded for combat, can pull nine-G turns with a full load of fuel and missiles. This cannot be done by fighters lugging along external weapons and fuel tanks..."

SOURCE: http://www.airforcemag.com/magazinearch ... ghter.aspx
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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basher54321

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Unread post19 Mar 2014, 00:51

spazsinbad wrote:The Air Force F-35 variant, fully loaded for combat, can pull nine-G turns with a full load of fuel and missiles. This cannot be done by fighters lugging along external weapons and fuel tanks..."



To be fair - Pulling it with missiles (A-A) you would expect - but certain A-G stores could still have a G limit on them could they not - if slightly higher than external carriage.

Also that quote could suggest it can handle 9G at More than 60% fuel.
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cola

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Unread post19 Mar 2014, 00:56

spazsinbad wrote:Somebody might know more than 'cola'

Well, I'm quoting Bowman, who certainly is the only one that gave any figures unlike dimensionless and therefore meaningless 'tea leaves oracle readings' from O'Bryan.
Cheers, Cola
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spazsinbad

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Unread post19 Mar 2014, 01:33

No quotes from 'Bowman' then? Do you refer to 5 yr old quotes or more recent ones? Enquiring mind wants to know.

Scorecard - A Case study of the Joint Strike Fighter Program April 2008 LCDR Bowman USN

"...The most notable differences are related to the USAF requirements for the CTOL JSF. The USAF includes a threshold requirement for a 9.0 G capability at 60% fuel and no air-to ground ordnance remaining. In addition to the high-end requirement, the USAF also provides for a more realistic scenario of high altitude, large payload performance. The CTOL must have the capability of performing a 30 degree bank turn while still maintaining a 1000 foot per minute climb at 30,000 feet with a combat loadout of two external fuel tanks, two external JDAM, two internal JDAM, two internal AIM-120 missiles, and a fully loaded gun...."

SOURCE: http://www.f-16.net/f-16_forum_download-id-14791.html (PDF 0.25Mb)
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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cola

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Unread post19 Mar 2014, 02:13

There you go...I thought Bowman's doc is so well known, there's no need to spam it here, again.
Anyway, unlike O'Bryan, Bowman is unequivocal and therefore relevant.
Also, there's a JPO statement released through Aviation Weekly where 240-3's performance is put in the Bowman's class, so why would a JSF be able to pull 9g with full fuel and bombs all of a sudden, when that was never KPPed nor claimed by anyone and the plane is even heavier now than it was before?
Just because O'Bryan's vague statement can be interpreted that way?
I mean seriously, the entire JSF PR campaign is based on misleading hints, like the one when g and accel. KPPs extensions raised concerns, to which LM replayed (paraphrasing here) "What did you expect, it's a strike fighter?".

Fans will believe anything and it's fine, but hardly relevant.
Cheers, Cola
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Corsair1963

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Unread post19 Mar 2014, 03:34

cola wrote:There you go...I thought Bowman's doc is so well known, there's no need to spam it here, again.
Anyway, unlike O'Bryan, Bowman is unequivocal and therefore relevant.
Also, there's a JPO statement released through Aviation Weekly where 240-3's performance is put in the Bowman's class, so why would a JSF be able to pull 9g with full fuel and bombs all of a sudden, when that was never KPPed nor claimed by anyone and the plane is even heavier now than it was before?
Just because O'Bryan's vague statement can be interpreted that way?
I mean seriously, the entire JSF PR campaign is based on misleading hints, like the one when g and accel. KPPs extensions raised concerns, to which LM replayed (paraphrasing here) "What did you expect, it's a strike fighter?"
Fans will believe anything and it's fine, but hardly relevant.



You mean Critics will believe anything...........Especially, critics that have no access to the JSF Program and haven't even flown the F-35. :doh:
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smsgtmac

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Unread post19 Mar 2014, 03:38

Wow. you guys are covering a lot of ground...again. :D

I would take (and have taken) Bowman's figures with a grain of salt, and caution others against leaning too hard on them either in support of the F-35 or in opposition to it.

First, they were old data points when he used them, and over time it is TYPICAL (uninformed whimpering to the contrary) for requirements to morph over time, or at the very least be recognized as either more important or less important as a program progresses.

Second, in some cases, such as the transsonic acceleration objectives/thresholds, they can be improperly specified in the first place: a 'clean' unloaded spec for a legacy fighter ignoring the internal stores-driven cross-section and wetted area. Gums has dropped hints about 'unloading' often enough, I'm surprised more people haven't picked up on the significance of that one little operational technique: it kind of trivializes the transsonic performance complaint all on its own. We've read LM bringing the 'clean spec' point up in interviews and public official testimony. The JSFPO, DOT&E, nor anyone else in the know has made a big deal of it. that should be the first clue. Most of all, I understand the math involved (working a similar tradeoff on a lesser scale right now) so I'm inclined to accept the acceleration spec as being no big thang. It is up to others outside the program to 'prove' otherwise...and they can't.

Third, Bowman is a NoGreatBrain F-18 Meat Servo, who wrote a mandatory paper to get through Air Command and Golf. It is hard to be any 'less' authoritative. I still hope he gets an F-35 billet before he's done [He's a 'Captain' now]: That would be truly Cosmic Justice!

This selective attention to individual specifications, while fun to some is irksome to those of us who look at total systems. What will be acceptable or unacceptable in F-35 performance for any particular KPP is how does it support the overall top-level program objectives? In cases of the Sustained G turn and Transonic Acceleration, those KPPS support the Survivability end Lethality objectives. As there are performance metrics no one has ever seen the 'measure' of (should we assume that DOT&E would only report it if they weren't being met?) for all we know those parameters obviate the utility of the ones the h8rs squawk endlessly about.

Think 'total package' when you think 'value' and no one outside program/user channels has a clue as to the 'total value'. Which I must admit makes it that much more pleasurable to watch the naysayers writhe in their lack of knowledge. They feel entitled to 'certainty' they have no right to have. And when they don't get it, things apparently look like 'smoke and mirrors' ,or perhaps 'misleading hints', to them. :wink:
Last edited by smsgtmac on 19 Mar 2014, 12:48, edited 1 time in total.
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