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F-35A vs. F-105D

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F-35A vs. F-105D

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Old 13th Apr 2016, 00:26
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Originally Posted by Bevo
This would have been a much more interesting thread had the OP asked about an aircraft like the F-15K instead of the F-105.
Go for it. If the moderators don't mind, I'm up for a wide-ranging discussion, and the F-15K should be part of it.

Here is another question: the F-35A has an engine that develops about 14,000 pounds more thrust than a F-105D (sans afterburner) and about 20,000 pounds of additional thrust in afterburner. Yet, the F-105D dramatically out preforms the F-35A in every flight dynamic metric. How can this be?
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Old 13th Apr 2016, 01:08
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I doubt it out performs F35A in every flight regimen. I would hazard a guess that the instantaneous and sustained turned rates in the F35 are far better than then F-105, as would be instantaneous and sustained G. Additionally these days you have consider the systems on the a/c and the ability to employ those systems as a flight characteristic, in which case there is no comparison.

But the fundamental difference is the F35 'performance' is optimised for Low Observability and so there is always going to be a slight compromise in terms of pure airframe performance to maximise (or minimise) radar cross section. As for the F-15 - great aircraft. But its not going to last that long in the type of airspace that F35 was designed to go up against.

Last edited by AutoBit; 13th Apr 2016 at 02:00.
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Old 13th Apr 2016, 02:28
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Originally Posted by AutoBit
I doubt it out performs F35A in every flight regimen. I would hazard a guess that the instantaneous and sustained turned rates in the F35 are far better than then F-105, as would be instantaneous and sustained G.
Respectfully, this: http://aviationweek.com/site-files/a...0Maneuvers.pdf strongly indicates that your guess might be off the mark.

Originally Posted by AutoBit
But the fundamental difference is the F35 'performance' is optimised for Low Observability and so there is always going to be a slight compromise in terms of pure airframe performance to maximise (or minimise) radar cross section.

Interesting. Does the F-22, which is also optimized for low observability, incorporate the same crippling airframe compromises?

Last edited by Channel 2; 13th Apr 2016 at 03:22.
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Old 13th Apr 2016, 04:08
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Ok. The discussion here is about F35 v F105 not F35 v F16. How would an F105 do against a F16?

That report has been well documented, and also well countered.

Finally the F22 has thrust vectoring which the F35 doesn't…..and neither does/did the F105. So back to the original discussion: F35 against F105 and my money's on F35.
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Old 13th Apr 2016, 07:34
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Originally Posted by Channel 2
Does the F-22, which is also optimized for low observability, incorporate the same crippling airframe compromises?
Crippling? Who said anything about crippling airframe compromises? F-35 is a compromise between aerodynamic performance (including energy manoeuvrability) and LO, and I would have liked to see some better performance in some areas, but you can hardly call it crippling.
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Old 13th Apr 2016, 07:44
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I guess going in on day 2 in a 105 would be so much more relaxing because you wouldn't even see what killed you.
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Old 13th Apr 2016, 08:44
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Reading this thread, I decided to look up some more info on the F-105 and found the following article. I share the link for your edification only...

Joint Strike Fighter = Thunderchief II? / Back to the Future in Battlefield Interdiction
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Old 13th Apr 2016, 10:05
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Something we can never know is how well the 105 would have done from day 2 onwards on the Viernam war if the enemy SAMs had been properly targeted.

Our day 2 onwards theory for this thread is likely to assume that SAMs had been targeted to make life in the air easier. The 105 never had that luxury.
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Old 13th Apr 2016, 11:45
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To compare one Vietnam era airframe to one current/future airframe is somewhat disingenuous. What matters is the total resources required to complete the task.

In Vietnam, to bomb a bridge for instance, in addition to the bomb carrying F105, the following aircraft would have been required:
  • Wild Weasels to identify and take out SAM sites
  • Air to Air Interceptors to provide top cover
  • Combat SAR in case anyone was shot down
  • Air cover for the combat SAR
  • Tankers for all the above

I'm sure others could add to this list.

If the F35 can identify and either destroy, avoid or not be spotted by SAM sites, then that potentially removes the need for Wild Weasels. If (big if...) it can provide its own air to air protection, that rolls the whole attack into one aircraft, and with guided bombs or missiles, the number of attempts required is reduced, so the attack force can be smaller still.

The cost per airframe is higher, but the resources required per attack are smaller, provided the kit is as good as is it says on the tin.
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Old 13th Apr 2016, 13:34
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28 aerial victories and a book titled: "F105 Thunderchief MiG killers of the Vietnam War" are somewhat incongruous accolades for an aircraft with "essentially zero air-to-air capability".
Excellent point!! I acknowledge the incongruity of the Thud's accomplishments. On the other hand the B-52 had many MiG and Sukhoi kills, the B-17 and B-24 had many Messerschmitt and Focke Wulf kills, and the B-29 had many Mitsubishi and Nakajima kills. That does not mean any of them had a real air-to-air capability.

And separately, putting GPS and a few glass panels in a Thud would not make it a modern attack aircraft that would be effective in today's air warfare environment. That environment has changed dramatically since Vietnam. I'd wager that even a very experienced Thud driver with multiple MiG kills over Vietnam if given a choice between a "modernized" Thud, an F-15E, an F/A-18E, and an F-35, he would not choose the Thud. Even if his choice was limited to the Thud and F-35, I'd wager he would not choose the Thud.
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Old 13th Apr 2016, 13:48
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The Thud operated in the most heavily defended airspace known up to then. She carried the strike mission very well until losses in accidents and combat ran the numbers down to where she'd lived out her useful life and was replaced, of course, with the ubiquitous mighty Fox-4.
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Old 13th Apr 2016, 14:00
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Interesting. Does the F-22, which is also optimized for low observability, incorporate the same crippling airframe compromises?
The F-35's airframe compromises are NOT just related to stealth and in any event are certainly not "crippliing".

The F-22 is optimized for air-to-air.
It has two engines. The F-35 was mandated by the government to have only one. That's a huge "compromise" all by itself. The F-22 is essentially single role and is single service and is optimized for that role and that service. Like so many other fighters, it is kind of a point design. The F-35 was mandated by the government to be multi-role, multi-service, AND multi-national. That requires LOTS of "compromises," the vast majority unrelated to stealth. The F-22 is optimized as an air superiority fighter and is a lousy bomber. The F-35 is optimized as a tactical bomber yet has a damn good fighter capability. The F-22 was so expensive that less than 200 will ever be built (including test airframes). Literally thousands of F-35s will be built. Quantity has a quality all its own.
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Old 13th Apr 2016, 16:22
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@KenV "The F-22 was so expensive that less than 200 will ever be built (including test airframes). Literally thousands of F-35s will be built. Quantity has a quality all its own."

Not to pick an argument with you, but I don't think the question should be to choose between F-22 or F-35, but I think its a damn crime that fewer than 200 F-22's were built. Such a waste of development costs and such a loss of potential military capability. And by the time the piper is paid, an awful lot more will have been paid for the F-35 than optimistically estimated when the F-22 buys were stopped. To build thousands of F-35's and less than 200 F-22's was a disastrous and wasteful political decision that will leave us wanting in the air superiority arena for decades to come. Just a lonely taxpayer's lament.
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Old 13th Apr 2016, 17:03
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Originally Posted by KenV
The F-35 was mandated by the government to have only one [engine]. That's a huge "compromise" all by itself.
Understood KenV. However, the F-35A has been provided with an incredibly powerful engine.

F-35A Powerplant: 1 × Pratt & Whitney F135 afterburning turbofan, minimum dry thrust: 28,000 lbf (125 kN) [That number may go to 32,000+ in the future.] in afterburner: 43,000 lbf (191 kN)

The F-35A's nominal thrust is significantly above what a F-4E could ever produce with two engines.

F-4E Powerplant: 2 × General Electric J79-GE-17A axial compressor turbojets, both engines combined produced: dry thrust: 23,810 lbf (10.8 kN), in afterburner: 35,690 lbf (158.8 kN)

The "tanks are full" thrust to weight ratio are quite similar. F-35A = .87 versus F-4E = .86.

However, the F-4E could do Mach 2.2 until it ran out of gas, while the F-35A struggles to achieve Mach 1.2, for a matter of seconds, (or until the vertical stabilizers over-temp and the sensors red-light the panel.)

Despite having near equal thrust to weight ratios, the F-4E outperforms the F-35A in every flight metric. And in most performance parameters, the F-4E shames the F-35A.

Why? Seriously. Why?

Last edited by Channel 2; 13th Apr 2016 at 17:40.
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Old 13th Apr 2016, 17:55
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Despite having near equal thrust to weight ratios, the F-4E outperforms the F-35A in every flight metric. And in most performance parameters, the F-4E shames the F-35A.
Aerodynamics are a funny thing Channel 2. The aircraft is, in essence, a huge lifting body (note total planform area compared to actual wing size). This is the same reason that the venerable F-16 has better turn performance, thought not by that much. High AoA (snap, shoot) of F-35 will make F-105D and F-16 eyes water as the handling characteristics are allegedly more akin to F-18 like, but with a +9gz limit (for the A). There's much more drag on the F-35 as soon as you pull AoA compared to the F-105 or F-16 - again, aerodynamics. That drag is a result of nearly 16k+ lbs of internal fuel, internal weapon bays and shape/form restrictions. One engine is a real limit on grunt overcoming the drag mentioned but....engine tech may provide restitution in that area in future, esp as total weight grows over time with upgrades etc.

Quoting the T/W ratios and postulating some very pointed assertions makes me a little suspicious, if you'll forgive me. Beyond the few similarities you mention (i.e. one of the F-35's missions) I'd say they're pretty much apples and oranges.

You clearly have an agenda in this little thought experiments and I'll leave it at that.
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Old 13th Apr 2016, 18:07
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Not to pick an argument with you, but I don't think the question should be to choose between F-22 or F-35, but I think its a damn crime that fewer than 200 F-22's were built.
You get no argument from me. Killing the F-22 line was a sad decision. My intent was to point out what some of the compromises were for the F-35 relative to the F-22. Contrary to the claim, the F-35's compromises were NOT primarily driven by stealth. The government mandate for a single engine was but one huge driver that required all sorts of compromises that simply did not apply to the F-22. There were many more.
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Old 13th Apr 2016, 19:08
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However, the F-4E could do Mach 2.2 until it ran out of gas, while the F-35A struggles to achieve Mach 1.2, for a matter of seconds, (or until the vertical stabilizers over-temp and the sensors red-light the panel.)
Despite having near equal thrust to weight ratios, the F-4E outperforms the F-35A in every flight metric. And in most performance parameters, the F-4E shames the F-35A.
Why? Seriously. Why?
Out performs the F-35A in every flight metric? You mentioned just one, top speed. What are the others? And what are the "performance parameters" other than top mach number where the F-4E "shames the F-35A?" Seriously.

And contrary to your claim that F-35 verticals limit its speed, the top speed is driven by the fixed engine inlets. The Phantom goes mach 2.2 because it has variable inlets. By your measure, the F-4 is superior to the F-22, which is also mach limited due to fixed inlets. High mach flight is of very limited value in modern air combat, and why the F-16 and F-18 are also mach limited due to fixed inlets. Do you really claim the F-4 "outperforms in every flight metric" the F-16, F-18, F-22, and F-35 because it's variable inlets give it a higher mach top end than those aircraft?
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Old 13th Apr 2016, 19:25
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Could you type that a bit slower please ..
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Old 13th Apr 2016, 19:27
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slow reader?




just a little humor
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Old 13th Apr 2016, 19:37
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Originally Posted by MSOCS
High AoA (snap, shoot) of F-35 will make F-105D and F-16 eyes water as the handling characteristics are allegedly more akin to F-18 like, but with a +9gz limit (for the A).
I hear what you're saying MSOCS, unfortunately, it has no basis in fact.

Excerpts from:

F-35A High Angle of Attack Operational Maneuvers

Overall, the most noticeable characteristic of the F-35A in a visual engagement was its lack of energy maneuverability. [...] Even with the limited F-16 target configuration, the F-35A remained at a distinct energy disadvantage for every engagement.

Pitch Rate

Insufficient pitch rate exacerbated the lack of EM. Energy deficit to the bandit would increase over time. The average Nz [“Nz” definition: Nose to Z axis / Pitch axis] achieved during the breaks or turn circle entries were typically ~6.5 [Definition: 6.5 g] or less despite a rapid full aft stick pull and then decreased as energy depleted and the aircraft slowed on the limiter. (You can forget about a clean F-35A being a “9g fighter” in the Z axis because it just won’t do it. And when they start hanging externals on it, that number is going to get way worse.) Insufficient pitch rate also occurred at slower speeds such as during gun run attempts. Instead of catching the bandit off-guard by rapidly pull aft to achieve lead, the nose rate was slow, allowing him to easily time his jink prior to a gun solution.

High Angle of Attack

Due to the energy and pitch rate limitations described above, there were not compelling reasons to fight in this region. [...]

High Angle of Attack Blended Region

The flying qualities in the blended region (20-26 degrees AOA) were not intuitive or favorable.
This was especially frustrating because as the sortie progressed, it was apparent that the aircraft fought best at the lower end of this alpha whether turning or established in a tree/scissors; so the lateral/directional control was often unpredictable. [...] Since this aircraft seemed to fight best near 20 degrees, [!!!] controls should not be blended near this region.

Guns Defense

No effective guns defense was found during this test. [...] For unloaded-roll-pull jinks, [The devastating word being: “unloaded.”] the slow pitch rate was evident in both the unload and the pull. [...] The result was a target [the F-35A] that was changing shape/attitude but not actually moving out of the piper. Higher alpha usually just resulted in a larger planform target.

Last edited by Channel 2; 13th Apr 2016 at 21:36.
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