F-35A vs B vs C

The F-35 compared with other modern jets.
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quicksilver

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Unread post12 Nov 2018, 12:41

“If you can provide links that prove the US Navy's increased maneuvering requirement was due to carrier approach retirements then I'd be happy to rest my case.”

No, YOU have failed to prove YOUR point. YOU provide proof of your claim.
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marsavian

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Unread post12 Nov 2018, 12:52

Right now, I'm just afraid that most of us here have become so bent on ruling out dogfights that we'd rather believe it was never a factor in the F-35's design phase.


Of course it was a factor but for the whole family. How else did you think they got such a stubby shape with relatively small wings to pull more than 20 degrees/sec. It was designed to deliver leading 4th gen maneuvering performance and as an overall maneuvering package they delivered. However the C was not given any special attention and just benefited a bit more under corner velocity from the bigger carrier wing fitted. It was a nice useful byproduct but the bigger wing is primarily designed to approach a flat deck more slowly with more control. You will not find a single reference to the C design that suggests greater dogfighting maneuverability than the A was ever a requirement but you will find plenty/all of them suggesting carrier adaptation was the driver for its design.
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quicksilver

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Unread post12 Nov 2018, 13:01

"The most influential requirement was the Navy's insistence on a large bring-back payload. By the time JIRD 3 was issued in 1998, the Navy had increased its total bring-back weight comprising fuel and weapons from 8000 to 9000 pounds and specified approach speed which had previously been left to the contractors discretion."
"Lockheed Martin could deal with this problem by enlarging the carrier-based JSF's wing, gaining low speed performance at the expense of transonic acceleration and speed. Boeing's tailless delta was in a more difficult position. The Navy requirements drove the size of the trailing edge controls upwards, but as Boeing sought to increase pitch authority with larger ailerons, the weight of the actuation system became unacceptable. The only answer was to add separate stabilizers and change the wing to a trapezoidal planform"

From page 71 of "Ultimate Fighter" by Bill Sweetman, Zenith Press, 2004

Kaboom. Accept it. Move on.
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zero-one

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Unread post12 Nov 2018, 13:54

quicksilver wrote:No, YOU have failed to prove YOUR point. YOU provide proof of your claim.


I failed??? When?
My point is common sense, any additional maneuvering requirement is for combat purposes not for carrier approaches.
There are many far less maneuverable Naval aircraft that had very little trouble approaching the aircraft carrier.

https://sldinfo.com/whitepapers/the-f-3 ... y-fighter/
Stealth is just one enabler of a 5th Generation fighter and in actuality we’ve had stealth in the past, but until the F-22 it wasn’t coupled with combat agility. Consider the B-2 and F-117. Both are very stealthy but lack agility, so much so that they could only be deployed at night.

The F-22 and the F-35, which also employ stealth, were designed for agility.


So from the beginning combat maneuverability was a component of the design, but the Navy wanted more because apparently they had enough agility to dogfight if needed but not enough to land on a carrier?
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marsavian

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Unread post12 Nov 2018, 14:29

The USAF is not prepared to take the acceleration hit due to the extra weight and drag of the big wing for any additional turn benefits under corner velocity which is why the A does not have the C wing. All designs are trade offs and A/B/C all made their own to suit their own missions, A basically has to get in and out of combat arenas quickly so acceleration is key. Basically the F-35 was shaped initially from the (X-35)B and the A and the C then derived from that base. Now it maybe sometime in the future when current orders are close to being filled that LMT looks at making a sleeker longer more streamlined A fuselage and marrying it with a C wing so acceleration hits are minimized or even cancelled with possible supercruise and greater Mach and endurance ensuing from this hybrid evolution but it certainly did not have the time or inclination to propose such a vehicle at design birth, it just had to meet all three service requirements cost-effectively with minimal changes from the STOVL base model.
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weasel1962

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Unread post12 Nov 2018, 15:21

For the benefit of non-pilot blokes like meself, in simple english, I always had the impression the F-18E had an increased wing area to reduce approach speeds so the plane can land more safely on the carrier. Assumed the F-35C just carried on what the USN learnt from the Super Hornet esp when a larger wing didn't really have a big impact on rcs.

Don't recall when the E got the bigger wings that the USN were arguing that the E was more maneverable than the C/D. Maybe I missed that. Interesting to read the comments.
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quicksilver

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Unread post12 Nov 2018, 15:43

“...but not enough to land on a carrier?”

Correct.

Aerodynamics 101 — make the jet heavier (i.e. increase bring-back) and you need more lift, particularly if you hold the approach airspeed constant (which they did by actually specifying one, which they had not previously done).
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zero-one

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Unread post12 Nov 2018, 15:49

No wait, I understand the requirement for increased lift as an obvious benefit for carrier bring back loads. What I'm saying is why did Boeing get compelled to add a tail?
I mean correct me if I'm wrong but the tail, specifically the tail design of the X-32 which extends far back from the aircraft's CG is used to increase the momentum arm, increasing pitch authority and pitch rates.
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Unread post12 Nov 2018, 15:51

“My point is common sense.”

Do you have a link to that?
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Unread post12 Nov 2018, 15:52

So let me as this question: If we want to bring back some of that acceleration performance, let's say equal to the F-35A, and the airframe can't really be changed, is the only solution a more powerful engine?

If so, how much more powerful? Something tells me it'll have to be north of 50,000lbs of thrust. Hopefully, another triumph of thrust over aerodynamics like the F-4?
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Unread post12 Nov 2018, 16:06

Yes.

Search PW ‘Growth Option 1.0’ and/or ‘Growth Option 2.0’
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Unread post12 Nov 2018, 16:17

http://www.dtic.mil/dtic/tr/fulltext/u2/a399988.pdf

For basic primer on ship stuff affecting aircraft design.
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zero-one

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Unread post12 Nov 2018, 16:34

quicksilver wrote:
“My point is common sense.”


Do you have a link to that?


Common QS, you're better than this.

Fine. To me, just for me, when you request for additional maneuverability your reasoning is probably combat related not carrier approach related. And since neither side has sent links on why the Navy requested for additional maneuverability then lets just say both sides are false, maybe its specifically for airshows, recruitment purposes or the new TopGun film, who knows.
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steve2267

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Unread post12 Nov 2018, 17:01

Wow. Flynn sure has a big mouth! One little tweet about snowboarding prompts pages upon pages of teeth gnashing and clothes rending over how "I wish the A had the C wing" --or-- "I wish the C could accelerate like the A, then ittud be purrfekt!"

I don't think I've seen internet bloviators so argue with bona fide nasal radiators and not simply take them at their word. Pressing the nasal radiator to "prove" his point relating to Aerodynamics 101 and Basic Aircraft Design Performance 101 -- priceless!!!

Thanks to QS and EllBeeKay for taking the time to patiently respond to these questions -- MORE than once. But if it hasn't sunk in by now... not sure if it ever will. EllBeeKay, thank you especially for your earlier BFM energy "point" treatise. It put words to thoughts I've had for a while.

ZeekOne, do you lack basic reading comprehension abilities? You recently wrote:
ZeroOne wrote:No wait, I understand the requirement for increased lift as an obvious benefit for carrier bring back loads. What I'm saying is why did Boeing get compelled to add a tail?
I mean correct me if I'm wrong but the tail, specifically the tail design of the X-32 which extends far back from the aircraft's CG is used to increase the momentum arm, increasing pitch authority and pitch rates.


Because I'm curious what part of QS' patient explanation, especially the emboldended part, you do not understand?

quicksilver wrote:"The most influential requirement was the Navy's insistence on a large bring-back payload. By the time JIRD 3 was issued in 1998, the Navy had increased its total bring-back weight comprising fuel and weapons from 8000 to 9000 pounds and specified approach speed which had previously been left to the contractors discretion."
"Lockheed Martin could deal with this problem by enlarging the carrier-based JSF's wing, gaining low speed performance at the expense of transonic acceleration and speed. Boeing's tailless delta was in a more difficult position. The Navy requirements drove the size of the trailing edge controls upwards, but as Boeing sought to increase pitch authority with larger ailerons, the weight of the actuation system became unacceptable. The only answer was to add separate stabilizers and change the wing to a trapezoidal planform"

From page 71 of "Ultimate Fighter" by Bill Sweetman, Zenith Press, 2004


So here is a case where NOT a 9gee gee-whiz-better-dogfighting-requirement, but a basic get-back-on-the-boat-safely requirement necessitated not just a wing size change, but an entire planform arrangement change.

Before I became a private piston-poppin' pilot, all I wanted to learn was how to design airfoils. Airfoil design was where it's at. Nothing else matters. Performance? Phooey. Takes a back seat to airfoils. Once I learned to fly, gee, it was really nice that the wings stay attached. I guess structures is kind of important too. Man, it's taking forever to get to Sioux City from Denver in this Cessna 172. A BIGGER motor (powerplant / performance) sure would be nice. Once I finally crawled into a Bonanza... WOW, these controls are SO much nicer than that Cessna that drove like a truck with loose steering. But... my son did puke halfway to Ogden because of that Bonanza boogey. A wee bit more stability would be nice in the Bo. I guess that's just the price to pay for fantastic roll feel. Hmmm... Josh, you'll just have to learn to suck it up...

There IS A LOT MORE to aircraft design / analysis / performance than just 9gees or getting to 1.2 Mach in XX seconds.

For those that wish the Cee monster could get the go-juice like the Aye stubby... well, as long as the jets remain kissing cousins, any bigger motor you stuff in the Cee will just make the Aye go that much faster. So the Cee will NEVER catch the Aye.

Regarding bigger motors... if memory serves, the GO 1.0 F135 block upgrade proposed by P&W had in its genesis a program by the Navy to improve the engine's hot section (increased turbine temps, I think) which yielded NOT more engine thrust, but increased fuel efficiency that the Navy was (and is) after. It didn't sound like much, only 2-3% (though it may have been 5%), for which the Navy gladly spent millions of dollars. I could ask... why did the Navy spend so much money on increasing fuel efficiency, and not making the Cee accelerate more like the Aye... --OR-- making it dogfight better. But they didn't. They wanted better gas mileage.

The Navy could have specified a 9g aircraft in the C. Why didn't they? They could have made that a spec. Maybe it's not all that important to them. Maybe the trade-off's necessary to get their would have broken the bank, engineering-wise -- or the program, $$-wise, to make it happen.

Watching a bloviator tell a nasal radiator to "prove" his point that the bigger C's wing was enlarged to meet a (mundane) land-on-the-boat requirement and not to improve "dogfight" performance is really rich. Can't make this stuff up. How audacious can you be?

Keep up this obtuseness, though, and these great resources who are patiently willing to share their experience, wisdom, and knowledge will decide they have better things to do with their time than beat their head (and keyboard fingers) against an internet rock.
Last edited by steve2267 on 12 Nov 2018, 17:28, edited 1 time in total.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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steve2267

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Unread post12 Nov 2018, 17:25

Z1 -- what are you hung up on? The Navy's 5g spec, which is higher than the Air Force / USMC 4.whatever spec? :doh:

As QS and EllBeeKay have patiently explained, the Cee's wing was sized by the back-to-the-boat landing (speed) requirements. A happy by-product of that wing is that the Cee turns really nicely (per Billie Flynn).

Perhaps the better question is NOT why is the Cee turning spec higher than the Aye/Bee but why can't the Aye & Bee sustain more gees than the Cee? Perhaps its not that the Cee's wing is so big... but that the Aye/Bee's wing is TOO SMALL! (HORROR!)

I could very well see some back-and-forth / give-and-take between the JPO and LM having gone something like this:

LM: Well... we can't make that sustained Gee spec and keep everything else the same. I mean, we could increase the wing size, but that will increase structural weight, and correspondingly, drag -- both induced and wave/form and skin friction. Acceleration will suffer.

Air Force: But we like that acceleration... I miss my Zipper.

USMC: We just want the fan...

LM: Well, we could lengthen it to reduce form drag, but it's still going to get heavier...

USMC: ...oh, and it has to fit through that hole in the boat...

LM: Well, then we can't lengthen it. If we could drop down from the 2000lb bomb requirement to thousand pounders...

Air Force: But we like our Mk-84's...

USMC: We just want the fan...

LM: Well, we did design the F-16... so we are something of aerodynamic wizards... but not even our Skunk Works boys can change the laws of physics... I just called them and checked to be sure. They mentioned some super secrete seance program, codename Ghost Whisperer, where they were trying to contact Sir Newton to see if he'd revise his laws so they could tweek Navier and Stokes equations... but so far he's not answering... So I'm sorry gentleman, we're between an acceleration and a hard lift place. Until Isaac revises his laws, you're going to have to choose... acceleration -- straightline, or centripetal...

Air Force: Oh, all right... we just like to go fast. We still get to keep our 9g requirement?

LM: Yes sir.

Air Force: Good. As long as it's higher than Navy!

USMC: Yeah, and the Navy can't float like a butterfly neither...

LM: There's just one other thing... while we're at it... If you have to have those Mk-84's... we're going to be 8 seconds slow to 1.2 Mach. It's a little worse with the Killer Bee. The hump from the fan you see..

USMC: Gotta have that fan. Love the fan...

Air Force: Ok... so we relax the sustained gee-spec a bit, a wee bit slower to 1.2 Mach, but we keep the Mk-84s and a higher gee-spec than the Navy? Done! The roosskies can't see us anyway...
Last edited by steve2267 on 12 Nov 2018, 17:49, edited 1 time in total.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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