F-35A vs B vs C

The F-35 compared with other modern jets.
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steve2267

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Unread post12 Nov 2018, 17:47

As an aside... as I've re-read what I have written, I could see where some people might get a little bent. I am not going to change what I wrote.

However, I will note that experienced military aviators such as quicksilver, and (I presume) lbk000, have been very kind to take the time to share their knowledge and experience.

Basically telling them they are wrong, or challenging them to prove their point, when the person arguing has NOT proven theirs (by any stretch of the imagination), is REALLY rich.

On the other hand, if the person stating the naval aviator is wrong had some bona fides along the lines of fighter test pilot for XXX or I was Harry Hillaker's protege, well, then that would be a slightly different argument. But I have not seen any such bona fides, nor writing style or substance to suggest such a case.

To wit, if you have a question, ask it in a polite fashion. I have observed nothing but generous, polite responses on this forum. If you still don't get it, but keep asking questions in a polite manner, I think you will continue to receive polite responses. If you keep asking the same question, and the answers don't seem to be getting through... then at some point, expect to be chidingly treated like a box of rocks, internet troll, or AI trollbot that has got stuck in some sort of goto loop. Come across as a know-it-all or a bloviator -- or tell experienced naval aviators they are wrong -- and I think one can reasonably expect to get stomped.
Take an F-16, stir in A-7, add dollop of F-117 & gob of F-22, sprinkle with AV-8B, stir well, then bake. Whaddya get? An F-35.
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Unread post12 Nov 2018, 18:24

steve2267 wrote:However, I will note that experienced military aviators such as quicksilver, and (I presume) lbk000, have been very kind to take the time to share their knowledge and experience.

Sorry, gotta stop you there -- I don't have the honor of being one of the Real McCoys here. I've had... "military-esque" experiences, but I can at best only claim to be an amateur historian. My understanding of BFM and energy is abstracted from sampling as many airplane simulations as I can -- and while I would never for one moment pretend that they deliver the full experience, sampling a wide range of approximated characteristics can give insights on the topic that books alone have trouble expressing. Being able to experience the difference in characteristics of aircraft through a wide range of time periods in particular was instructive on the changing doctrinal demands and the varied mindsets of their creators.

I do think that, as lacking as simulators are in fidelity to the real thing, they are still more effective than books alone. However, hints gleaned from information in writing are absolutely necessary as guidelines to reconstruct procedures (and by extension, mindsets, which is the real object of value) in the sandbox of simulation, otherwise it can rapidly devolve into a purely autoerotic exercise.
One of the big problems with books is that the priority of the information given is rarely established. Yet priority is the lynchpin in forming correct decisions, as prioritization is what creates the hierarchy that materializes form (gotta be "making heads and tails..."). In creating interest and drama, false prioritizations are often unwittingly emphasized -- cherry picking just combat accounts to cater to audience interest factors into the formation of a false impression on the dynamics of armed conflict. There's also a lot of bogus and myths that sensationalist authors love to perpetuate (F-15 TWR allowing vertical acceleration is particularly infamous), and so in respect to being held to limitations and structure of reality, simulations have an advantage in fidelity over the written account. It's a sort of check and balance thing.

Segueing back to the topic of the thread... priority is everything, and everything I've learned points to the fact that tactical level considerations such as WVR, and within WVR, flat turning capability, as a matter of far lesser priority than higher-level matters with near-strategic impact such as response time (speed, range, and endurance) and even higher beyond that, availability (basing, safety, and serviceability). This hierarchy is what supports that the correct attribution to F-35C design is owed to the carrier landing requirement, and any positive impact it has on flat turning capability is purely ancillary.
Last edited by lbk000 on 12 Nov 2018, 19:25, edited 1 time in total.
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steve2267

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Unread post12 Nov 2018, 19:09

Well, ya fooled me.

Nevertheless, I have found your posts to be well written and cogent, adding to the pool of knowledge found here or adding understanding of said pool. And for that I thank you.

To some points you made earlier about the larger wing of the F-35C... I suspect the Cee may stop quicker than the Aye as in addition to the larger wing area, it also has larger control surfaces -- the stabilators being larger plus it has ailerons. I look forward to reading comments in the future from some pilots who have flown both and may comment on this topic.

One day while I was perusing the Hellenic F-16C Block 50/52 PIlot AIM / FM, specifically the doghouse plots, I was pondering how an F-35 B / C could possibly hang with other fighters in BFM / ACM, as several pilots had noted you really couldn't tell the difference in performance vis-a-vis F-35A vs F-35B vs F-35C. HOW COULD THIS BE I thought if the F-35A is a 9g aircraft, and the other aircraft are only 7 and 7.5g airframes? The two answers I came up with were first perhaps one is not fighting at (or sustaining for very long) 9g or 9g very long and second, what if this "decelerates faster than a car" (comment by Maj Dolbe Hanche) and "accelerates faster than an F-16C Block 50" ability means a pilot could rapidly decelerate to his best turn speed to turn (rate) with (or possibly inside -- outradius) his opponent, then rapidly accelerate as he unload the aircraft. This second thought led me to wonder if it would not be possible then, for a 7.5g F-35C or 7g F-35B to slow down to his best turning speed (I dunno -- 300 knots?) while his opponent rockets around at 400+ knots grunting through (and tiring himself out from) a 9g rate. Without complete Ps curves for the three different models, this "guess" cannot be tested. But, to me anyway, it smells true. It makes me look forward to the day when I read new comments or statements by F-35 pilots about the performance of their steed.

In the one communication I had with a Bee driver, he stated the Hornet could (barely) outradius him, but he could outrate the Hornet. He said a clean Viper (think airshow clean) could (barely) outrate him, but he could outradius the Viper. Combined with the reports of truly carefree handling, the ability to slow faster than a car and out-accelerate a Block 50 Viper, it leaves me with a picture of an idiot savante WVR BFM/ACM machine that can effortlessly beat you at this, and effortlessly transition to another BFM regime or tactic if one idea isn't working out. It makes me wonder what I don't know rather than questioning Air Force / USMC / USN specs. What don't I know? And the more I learn, the more I realize how little I know.
Take an F-16, stir in A-7, add dollop of F-117 & gob of F-22, sprinkle with AV-8B, stir well, then bake. Whaddya get? An F-35.
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Unread post12 Nov 2018, 21:30

Well, one thing I see a lot of is the implication of the G as an absolute metric of performance. It's not.
Pulling more G does not guarantee you are outfighting the other guy.

Wtf does that mean?
Firstly an anecdote. Playing against a friend in mock head to head merges, I too once thought that G can be used as a metric of performance. Combined with the mantra I heard down the grapevine that "speed is life" I would enter a merge as fast as I possibly could (450kts or so) and then pull until I encountered blackout, which I considered a "good sign" because it meant I was pulling G's. Then I'd get smashed. I asked, "Wow how are you turning around faster than me?" after about the 4th time this happened. He didn't explain it to me at the time, but I later discovered that I wasn't considering the geometric portion of the fight. My opponent was winning because he attempted to pull fewer G's than me by entering the turn at a lower speed, and the coupling of the smaller turn radius with the speed at which he went through his turn brought his nose around on me sooner. You've heard of this phenomenon of course, this is the neighborhood of the magical "corner speed" turn.

Here's how I really started to understand the relationship of airspeed to angles to G (the turn diagrams never really helped):

At low separation ranges like this, little speed and consequently little G is required to produce a large apparent angle change. This why missile jinking requires a certain proximity, and why flying at the missile is (er... was) safer and more effective for kinematic avoidance than flying away. With the right geometry, a 4G pull can require a missile to pull over 20G's to intercept.
angle1-1.jpg
angle1-2.jpg

At greater separation distances, more work needs to be done to produce angular changes. The defending aircraft here must accelerate to a higher airspeed to move through the attackers field of view, and consequently be loaded to higher G.
angle2-1.jpg
angle2-2.jpg

So effective maneuvering exists between two desires: on one end is the need to be as close to the opponent as possible in order to effect the greatest apparent angular changes, and on the other end the necessity to keep yourself aloft by keeping enough air moving over your wings. The "harmonious compromise" here is the max sustained rate turn, it's the slowest, smallest turn you can make that you can maintain. If you sacrifice more airspeed for the smaller radius, you encounter maximum instantaneous rate before the compounding losses in energy catches up with you and drags your airfoil into ineffectiveness. When pilots tell you "speed is life" they just mean that you need to try to keep the air moving over your wings so you don't end up sliding off the doghouse.

You're probably tired of hearing me say this, but again, all airfoils are designed with a particular airspeed band. It is the relationship between your aircraft's design goal speed versus the opponent's aircraft's design goal speed that determines how you fight them.

An F-16 against an FA-18 cannot challenge the latter to a radius contest. It would be suicidal. Think of it as playing chicken limbo; the FA-18 is a nearly straight-winged aircraft when it comes down to it (20 degree sweep!) and it will always be able to go one rung lower than the F-16. So the F-16 will want to keep the ball in its court: running fast circles around the FA-18 until, by gaining one degree at a time, it winds up behind the FA-18. The FA-18 would love nothing more than to sucker the F-16 down into it's home turf: wallowing around as slow as the F-16 is stupid enough to go, because the FA-18 is the master of all the domain below, like, 300kias. Down at 280, 250 knots, you will be extremely hard pressed to generate 6G's; the only way you may be able to do it is by an AoA excursion resulting in massive deceleration... well now you've got no airspeed! Oops! Starting to see why talking purely in terms of G's is silly?

The situation turns on its head in a contest between an FA-18 and an A6M. Even without going into a numerical comparison, the A6M can be readily assumed to be far superior to the FA-18 in turn rate and radius. The A6M becomes master of the low speed dominion, the undisputed king of chicken limbo (at least in this matchup). The FA-18 suddenly takes on the role that the F-16 did in the previous matchup; it has to keep the A6M at arms length until its nose is pointed at it. It needs to use its far superior topend speed to move itself around... although for the FA-18 in this case, the discrepancy between its performance and the A6M is far too great to simply "run circles around" because the A6M is almost like a static turret and can always keep it's nose pointed at the FA-18 due to the combination of how small its turn radius and rate are. The FA-18 can recourse to an even simpler tactic by abusing the A6M's slow speed -- it can just fly away, do a U-turn, and shoot it. But let's just say that FA-18 decided to be greedy and turn against the A6M. I'm not going to do the math but I'll tell you that it won't take anywhere close to 6G's at 130kts for the A6M to easily win the contest.

Takeaway #1: Every discrepancy in performance represents an opportunity to exploit.
Takeaway #2: Your best airspeed is relative, your best G is also dynamic.

As a side note, this concept of "suckering" the other guy is, to me, the Human heart of aerial dogfighting; this is where the pilot egotism really expresses itself. Anyone who tries to play copycat with his opponent in DACT is most susceptible to getting suckered: he will be promptly led by the nose down to his opponent's favorite dark airspeed alley and ended. Experienced pilots all know what their best game is, and they will each keep insisting on only playing that game. The pilot that caves to the other guy's routine first, loses.

A lot of people also want to know, which is better, rate fighting or radius fighting? The reason I made up the two scenarios above is the disclaimer: you are never always the rate fighter, nor will you ever always be the radius fighter. Against a dirigible, even a biplane becomes a rate fighter. For me, the deciding factor is the fact that rate fighting generally has the initiative in engaging, and the freedom of disengaging. That really tips the theoretical scales in favor of faster, more energetic designs.
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Unread post12 Nov 2018, 22:59

http://robertheffley.com/docs/HQs/NAVAIR_2002_71.pdf

For those inclined to more understanding of carrier suit’ and aircraft design; an excellent reference which includes substantial historical references.
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Unread post13 Nov 2018, 00:14

quicksilver wrote:http://robertheffley.com/docs/HQs/NAVAIR_2002_71.pdf

For those inclined to more understanding of carrier suit’ and aircraft design; an excellent reference which includes substantial historical references.


Lockheed had proposed a common planform for all variants; the Navy version would have used blown flaps
(adapted roll control jets from the STOVL version) but the Navy was and is hostile to boundary layer control as
evidenced in part by its rather perfunctory treatment in that paper.
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Unread post13 Nov 2018, 00:39

steve2267 wrote:It makes me wonder what I don't know rather than questioning Air Force / USMC / USN specs. What don't I know? And the more I learn, the more I realize how little I know.


So true, a little knowledge can be a dangerous thing.
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Unread post13 Nov 2018, 01:14

It would be interesting to understand how new knowledge (gained in development and flight test since 2002) has altered the authors’ views.
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Unread post13 Nov 2018, 05:03

Robert Heffley PDFs: https://www.robertheffley.com/pages/bib ... d_Analysis

Outer-Loop Control Factors for Carrier Aircraft, Robert Heffley Engineering TR-RHE-NAV-90-1, 1 Dec 1990. (.pdf 900 KB)

https://www.robertheffley.com/docs/HQs/ ... 0_TR_1.pdf
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Unread post13 Nov 2018, 08:10

steve2267 wrote:If you keep asking the same question, and the answers don't seem to be getting through... then at some point, expect to be chidingly treated like a box of rocks, internet troll, or AI trollbot that has got stuck in some sort of goto loop. Come across as a know-it-all or a bloviator -- or tell experienced naval aviators they are wrong -- and I think one can reasonably expect to get stomped.

Easy there, No need to get fired up. no one here is asking in an unpolite fashion. So far all I've seen is a healthy discussion of opinions, to which I'd like to thank all of you. QS, LBK and Spaz. Thank you.


I'm trying to find documentations on the Navy's requirement for their JSF. So far I've seen that they changed their bring back load requirement and their maneuvering requirement and if I'm reading some the comments correctly they are related. I was thinking they were separate
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Unread post13 Nov 2018, 08:46

lbk000 wrote:
Takeaway #1: Every discrepancy in performance represents an opportunity to exploit.
Takeaway #2: Your best airspeed is relative, your best G is also dynamic.


Great insights..
This was also explained beautifully by GM, a Hornet driver here:
https://fightersweep.com/4210/dogfighti ... 18-hornet/
Generally speaking, a 1-circle fight can be considered a radius fight and a 2-circle fight can be considered a rate fight. This is illustrated below:


The trend today seems to be to combine both, since the Su-27, top end air superiority fighters can now excel in both radius and rate fights.

I'm curious though, is it easier to upgrade a radius fighter into a rate fighter by simply putting in bigger motors (i.e. Advanced superhornet proposal) or to make rate fighters into Radius fighters by some FCLWAS wizardry or TVC (i.e. J-10
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Unread post13 Nov 2018, 09:26

The F-35C is not worth a damn if it cannot meet the KPPs required of it, especially carrier landing. Perhaps a 'dog' F-35C could operate ashore (not on the carrier) but there would not be many of them eh. The Shornet MkIII would rool AvNav.

For the life of me I cannot see how the design of the F-35C as a JOINT STRIKE FIGHTER gets separated into many parts (that you would have) competing against each other. Brilliant engineers with all kinds of expertise tossed that salad and only screwed up with the AHS Arresting Hook System because they were given 'a decimal point in the wrong place set of numbers' from NavAir (these people were 'wire brushed' according to the Amirable of the time). Now the F-35C is a '3 wire machine' meeting all the requirements. Sure there were some glitches otherwise early on - but solved. F-35C newbies now know how to strap in tightly (properly) so soon there will be an USN IOC for the F-35C. :twisted: Even Marines can fly it. :mrgreen:
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Unread post13 Nov 2018, 21:41

steve2267 wrote: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...



2000 lb bomb was yet another navy requirement. I've taken this "extreme" position before, (but why not once more in thread that compares all 3 varaints??) the F-35C NOT the F-35B as so many claim is the problem child. Its the most different the Navy desire to have 2K bombs lead to a weight increase that then had to be tamped down with the SWAT effort which lead to huge delays. Irony being what is is the service that was the biggest pain in the butt with the F-35 program is also the service that has the Super Hornet and seems very happy with them (that will change of course)


F-35C has the most specific requirements and is the most specialized and least export desired variant. Hindsight being what it is, the program would have gone a lot smoother without the C, and for those of you who studied your history F-35B despite the variants alphabetical placement was the "first" version of the "JSF" as its origins and the liftfan breakthrough go back to pre JSF days. Then, when the USAF was touring the Skunk Works they showed the theoretical STOVL plane the Marines had inquired about and told them they could switch the lift fan out for a Fuel tank, and the USMC and USAF teamed up with fairly modest goal believe it or not. The USMC was more than happy to acquiesce to any air force request providing they got to keep the STOVL aboard. from what I can tell the 2 services were pretty like minded. Both were fine with 1000 pounders for example.


Yes thats right. I'm telling you the navy CVN requirements are less forgiving than asking for a hovering, mach capable stealth fighter that handles like an F-18.

And now if you'll indulge a quick rant. Americans don't understand the USMCs need for an on call STOVL like they do the USN's need to shoot an airplane off the front of a ship with a catapult because of all the highyl successful public relations of the US Marines, There is on movie involving CVN Aviation we simply can't usurp:

Image


So thats why most everyone else uses STOVL from ships, but only the US is weird and wrong for doing so according to joe public.
Last edited by XanderCrews on 13 Nov 2018, 22:07, edited 1 time in total.
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Unread post13 Nov 2018, 22:06

To be fair, the "requirement" is not what drove up the weight... It was LM's FK up in calculating the weight of "empty space".

This is why all 3 variants were overweight.
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