Why no tri or quad jet fighters?

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sferrin

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Unread post16 Jun 2018, 00:57

madrat wrote:The F-101 was probably the most comparable to F-106. The F-101 did out distance the F-106 nearly as much as F-106 clearly had more top end speed. The frontal area of the two is similar. The J57 didn't have near the high speed performance and probably explains a large amount of the speed difference. Both were about the same length. The F-101 did carry a bigger internal fuel load so no doubt that contributes to the range difference. So two similarly powered jet fighters with drastically different results by design.


The F-101 had about 38% more power than the F-106 (33,800lbs thrust vs 24,500lbs), not to mention the F-106 was a WAY cleaner design. (Weapons carried internally instead of semi-recessed in the case of the F-101. and never mind the huge aerodynamic difference of the airframes.) As for frontal area:

Untitled-1.jpg


The F-101's lower speed had less to do with the J57s high speed performance and more to do with the fact that, compared to the F-106, it had the aerodynamics of a brick.
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madrat

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Unread post16 Jun 2018, 02:35

It's awkward having a stalker.
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basher54321

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Unread post16 Jun 2018, 13:19

He is pretty much right though the idea that the J-57 itself was some how a top speed limiting factor is a new one on me.

See the last paragraph here - includes inlet and ramp changes that would let the J-57 produce more thrust at high Mach.


F-101B.JPG
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sferrin

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Unread post16 Jun 2018, 14:16

madrat wrote:It's awkward having a stalker.


Don't flatter yourself. I responded to your asinine claim (that electric motors could replace turbofans in fighters).

I don't see a tri or quad jet fighter serving in anyone's air force anytime soon.

madrat wrote:No, but its not ridiculous to believe it couldn't happen with electric drives. Unlike fuel-based engines, electric motors have an extreme high thrust to weight.


You desperately avoided justifying your claim and here we are.
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madrat

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Unread post16 Jun 2018, 15:47

The fact you continue to harp on a lie is overly aggressive. Grow up. Never said replace, nor did I say use as the sole motor. Keep pushing that lie. You're obviously following up my posts with an agenda and not with an actual argument. Rather, you're trolling for some kind of response.

Btw - basher64321 actually is arguing we are both wrong. His contention is that J57 wasn't responsible for the speed limitations, nor that F-101 was a flying brick. He posted an argument that demonstrated with changes to the intake it could reach Mach 2.1, which is much less different than the F-106 performance. His argument still comes up short on the argument the J57 has the ability to perform relative to the J75 at high speed. I'm not convinced, but at least he's arguing from a factual basis.
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sferrin

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Unread post16 Jun 2018, 16:20

madrat wrote:The fact you continue to harp on a lie is overly aggressive. Grow up. Never said replace, nor did I say use as the sole motor. Keep pushing that lie. You're obviously following up my posts with an agenda and not with an actual argument. Rather, you're trolling for some kind of response.


Your own words tell a different story. I've quoted them several times.

madrat wrote:Btw - basher64321 actually is arguing we are both wrong. His contention is that J57 wasn't responsible for the speed limitations, nor that F-101 was a flying brick.


Uh YOU'RE the one that stated the J57 was the problem. And the fact that both the intakes would need to be completely changed AND that the nose would need to be changed supports my statement re. F-101 and bricks.

madrat wrote:He posted an argument that demonstrated with changes to the intake it could reach Mach 2.1, which is much less different than the F-106 performance.


Intake and NOSE, ie aerodynamics.

madrat wrote:His argument still comes up short on the argument the J57 has the ability to perform relative to the J75 at high speed. I'm not convinced, but at least he's arguing from a factual basis.


Where is your evidence to support your claim the J57 lacked high speed ability?
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madrat

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Unread post16 Jun 2018, 17:31

The nose in the F-101 wasn't designed for the speed, but there is no evidence that its shape was the issue.

Care to name the J57 equipped production fighter that actually flew the top speeds flown by production F-101? The J75 wasn't a fresh design, it was a successor to J57. Surely you're trying to make an argument that wouldn't quite fit history. We know what the redesigned F-101 became; the F-110 Spectre.
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basher54321

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Unread post16 Jun 2018, 19:06

madrat wrote:Btw - basher64321 actually is arguing we are both wrong. His contention is that J57 wasn't responsible for the speed limitations, nor that F-101 was a flying brick. He posted an argument that demonstrated with changes to the intake it could reach Mach 2.1, which is much less different than the F-106 performance. His argument still comes up short on the argument the J57 has the ability to perform relative to the J75 at high speed. I'm not convinced, but at least he's arguing from a factual basis.


hmm just posting something that shows exactly what it would take to alter the F-101 to get it to M2.1.

The document proves that the F-101 was speed limited by the fact it did not have the thrust to over come the drag of its airframe thus this was the only speed limit nothing else. (it simply had a lower T/D than the F-106)


So to get to M2.1 they:
1. Increased thrust by altering the airframe inlet/ramps to allow an airflow that will let the J-57 put out more thrust at high Mach.

2. Altered the nose - not known although drag reduction would seem logical.

There is no requirement to swap the engine so the J-57 very likley good for M2.1.

sferrin stated the twin J-57s were already putting out more thrust at top speed than the single J-75 because it has a 38% higher static SL thrust. Don't have the thrust curves to prove it but I don't think it is unreasonable to think that they are and if so that would make the F-101 airframe far more draggy than the F-106s.
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Unread post16 Jun 2018, 20:54

Not many airframes were as optimized for low drag flight as the F-106. But it is reasonable to assume the J75, built on what they learned from J57, was optimized for the very flight regime it was used in the F-106. The F-101 had very good high altitude performance, it just didn't have the sustained thrust at high speeds. I simply demonstrated a single engine design against a twin engine design where the twin actually was under-performing compared to the single in speed, but it certainly had a higher fuel fraction so it outranged the single. I'm pretty sure this parallels the argument collimatrix made earlier that a single engine doesn't mean lesser performing. In this demonstration the aircraft were roughly the same length and similar eras. However, the twin's advantage- even with a large margin of extra thrust - was no indicator it would win in performance.
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Unread post16 Jun 2018, 23:51

For information concerning the F-106, you guys need to have a look at Bruce Gordon's Youtube page.
https://www.youtube.com/watch?v=8FQxKkJOvHY

He flew the Six back when Century Series jets ruled the sky. Also, it seems that the 106 not only has a smaller frontal cross section than the 101, its fuselage also appears more finely area ruled (I believe).


We need to have Gums chime in about the 101. :D
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sferrin

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Unread post17 Jun 2018, 01:29

madrat wrote:The nose in the F-101 wasn't designed for the speed, but there is no evidence that its shape was the issue.


You mean other than the fact that to go faster they would have needed to change it?
madrat wrote:Care to name the J57 equipped production fighter that actually flew the top speeds flown by production F-101?


So no source for your claim. Well, nobody is more shocked than I. :roll:

madrat wrote:The J75 wasn't a fresh design, it was a successor to J57.


And? So what? We're talking about the J57 and it's supposed lack of high speed capability.

madrat wrote: Surely you're trying to make an argument that wouldn't quite fit history. We know what the redesigned F-101 became; the F-110 Spectre.


Well I don't know what YOU know but the rest of us know the F-4 as being a descendant of the F3H-G, which descends from the F3H Demon NOT the F-101.

Capture.JPG


Copy of F3H-GH Brickman.jpg


F3H-GHmockupatMcDonnell-2.jpg


McDonnell_F3H-G_mockup_in_1954.jpg
Last edited by sferrin on 17 Jun 2018, 01:39, edited 1 time in total.
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sferrin

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Unread post17 Jun 2018, 01:35

madrat wrote:But it is reasonable to assume the J75, built on what they learned from J57, was optimized for the very flight regime it was used in the F-106.


That would explain why it was used in the U-2, the SeaMaster (that's a flying boat), 707, and DC-8.
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madrat

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Unread post17 Jun 2018, 03:59

sferrin wrote:
madrat wrote:But it is reasonable to assume the J75, built on what they learned from J57, was optimized for the very flight regime it was used in the F-106.


That would explain why it was used in the U-2, the SeaMaster (that's a flying boat), 707, and DC-8.


Early U-2 variants were powered by Pratt & Whitney J57 turbojet engines. The U-2C and TR-1A variants used the more powerful Pratt & Whitney J75 turbojet. The U-2S and TU-2S variants incorporated the even more powerful General Electric F118 turbofan engine. So what are you trying to say about the U-2? I'm pretty sure I've read the fuel was more difficult to choose than the engine. And you realize an F-101 was taken to 100,000 feet? Sometimes I just don't get your point you're attempting to make. That's the thing with trolls, they don't often seem to make sense.

The F-101 was a fighter armed with internal Falcon & Genie missiles. The F3H was a Sparrow equipped fighter. Sure looks like the McDonnell team put a little of both into the F-110A Spectre design.
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Last edited by madrat on 17 Jun 2018, 05:02, edited 1 time in total.
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sferrin

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Unread post17 Jun 2018, 04:52

madrat wrote:
sferrin wrote:
madrat wrote:But it is reasonable to assume the J75, built on what they learned from J57, was optimized for the very flight regime it was used in the F-106.


That would explain why it was used in the U-2, the SeaMaster (that's a flying boat), 707, and DC-8.


Early U-2 variants were powered by Pratt & Whitney J57 turbojet engines. The U-2C and TR-1A variants used the more powerful Pratt & Whitney J75 turbojet. The U-2S and TU-2S variants incorporated the even more powerful General Electric F118 turbofan engine. So what are you trying to say about the U-2? I'm pretty sure I've read the fuel was more difficult to choose than the engine. And you realize an F-101 was taken to 100,000 feet? Sometimes I just don't get your point you're attempting to make. That's the thing with trolls, they don't often seem to make sense.



I'm 100% certain you're the only one who doesn't understand. So where is your evidence that the J57 had poor performance at high speed? Sources please.
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madrat

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Unread post17 Jun 2018, 05:11

Actually, I think people abandoned the thread early due to your immediate commentary that devolved into your continued over-aggressive and irrational tone. I understand just fine that the J57 wasn't suitable to for the high speed performance that was desired by the F-106 or F-110 programs. J57 certainly had few issues in the scope it was utilized.

You certainly just want me to say I was wrong and you were correct. It's not going to happen. It's unnecessary considering the lack of honesty if I did. And I quite frankly don't want to encourage your poor behavior.
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