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F-4 Phantom engine upgrade

SSgtC

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Hi everyone! First post on this forum. I've been researching possible upgrades to the F-4 Phantom and stumbled across this site. I'm hoping someone may be able to give me a hand. I'm trying to investigate the possibility of an early to mid 70s engine upgrade for the F-4 Phantom. Specifically I want to see how feasible it would be to swap out the J79 for something like the PW1120 (or similar) a few years earlier than Israel tried it and Boeing offered it.

I have read that the Navy had some interest in replacing the J79 with a derivative of the F401 (itself a derivative of the F100). Had the Navy not cancelled the project after the F401 failed it's 60 hour endurance test, could they have then gone on to downsize the engine to fit the Phantom? Or have designed one from the start for the F-4?
 

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Hi SSgtC,

I think you are talking about what was called the “Enhanced Phantom”. It was a very comprehensive program that it also included an avionics upgrade and new conformal tank.

Here is a link to my blog post about it

https://nobarrelrolls.blogspot.com/2018/10/enhanced-phantom.html
Similar, yes. That is where I got the original idea from. But I'm thinking something maybe a little less ambitious.

I'm currently writing an alternate history timeline of the Cold War with a focus on the Essex class carriers. In the TL, they will be serving in the Attack role through the 1980s due to various reasons including a more unstable world and the need for a larger carrier fleet. As a result of events in the TL, the Navy will be putting Phantoms on those ships (it is technically feasible, they were trialed on Intrepid in 1960). So I'm basically looking for ways to keep the F-4 fleet viable longer, but at as low a cost as possible. And reengining them is the easiest way to do this (it also makes operation of the smaller Essex class far easier with a lot more thrust to get off the deck).

That's also why I'm looking for an early to mid 70s timeframe. Past that and the class won't be in service long enough to make it cost effective. Otherwise I'd say they should just drop in an F404 and call it a day (the J79 and F404 are remarkably similar with the F404 being shorter and lighter).
 

SSgtC

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SSgtC why don’t you keep the J79 and concentrate in upgrading the avionics? Many nations that kept their F4s through the 80s and 90s did that
The problem is the cats on the Essex class. The C11 cat struggled to get a Phantom into the air when it was hot and the aircraft was heavy. Adding a few thousand pounds of thrust (and deleting a couple thousand pounds of weight) helps that problem immeasurably. The USN had a possible fix for it (essentially an F-4K with the J79 and without the blown flaps) that would allow the C11 to launch a fully loaded Phantom at 90° temperature. But I don't see the Navy wanting a special model of Phantom just for the Essex. New engines are useful for every model.

Edit: In the TL, the Navy will also have zero interest in upgrading the Phantom too much and endangering the F-14 program. New engines (that are very close to "off the shelf") can be sold as a limited, though still useful, upgrade to keep the fleet viable until they are phased out of service.
 
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Archibald

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Yup. I sincerely hope however that this forum will never sink to rock bottom - as happened to AH.com. A case could be make that a competent, unbiased and democratic moderator team is more necessary than ever to keep a forum in good shape.

Hint: I registered here in 2007, only weeks before registering at AH.com. I can tell you, I've seen the difference in moderation between the two places... o_Oo_Oo_O

NASAspaceflight is another matter, altogether: SpaceX fanboism is a huge plague. It is insane, how that company can turn valuable people into ruthless and mindless fanatics...
What ? How do you dare suggesting Saint *Genius* Elon Starship ain't the best RLV thing since bread come in slices ? Burn him, burn the heretic at the stake ! A wiiiiitch (Monty Python style). No surprise old members like Jim (the Jim) deserted the place. Ed Kyle carry on despite all the fanboism and hatred, I wonder how he can stands that...
 
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NoBarrelRolls

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SSgtC why don’t you keep the J79 and concentrate in upgrading the avionics? Many nations that kept their F4s through the 80s and 90s did that
The problem is the cats on the Essex class. The C11 cat struggled to get a Phantom into the air when it was hot and the aircraft was heavy. Adding a few thousand pounds of thrust (and deleting a couple thousand pounds of weight) helps that problem immeasurably. The USN had a possible fix for it (essentially an F-4K with the J79 and without the blown flaps) that would allow the C11 to launch a fully loaded Phantom at 90° temperature. But I don't see the Navy wanting a special model of Phantom just for the Essex. New engines are useful for every model.

Edit: In the TL, the Navy will also have zero interest in upgrading the Phantom too much and endangering the F-14 program. New engines (that are very close to "off the shelf") can be sold as a limited, though still useful, upgrade to keep the fleet viable until they are phased out of service.
I see your point, in that case, the F404 would be the best option in my opinion.
 

SSgtC

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SSgtC why don’t you keep the J79 and concentrate in upgrading the avionics? Many nations that kept their F4s through the 80s and 90s did that
The problem is the cats on the Essex class. The C11 cat struggled to get a Phantom into the air when it was hot and the aircraft was heavy. Adding a few thousand pounds of thrust (and deleting a couple thousand pounds of weight) helps that problem immeasurably. The USN had a possible fix for it (essentially an F-4K with the J79 and without the blown flaps) that would allow the C11 to launch a fully loaded Phantom at 90° temperature. But I don't see the Navy wanting a special model of Phantom just for the Essex. New engines are useful for every model.

Edit: In the TL, the Navy will also have zero interest in upgrading the Phantom too much and endangering the F-14 program. New engines (that are very close to "off the shelf") can be sold as a limited, though still useful, upgrade to keep the fleet viable until they are phased out of service.
I see your point, in that case, the F404 would be the best option in my opinion.
The problem with the F404 is that it by the time it was available, so was the Hornet, which was replacing the F-4 in service. That and, while it was significantly lighter with much higher reliability and lower fuel burn, it offered no additional thrust over the J79. Otherwise the engine would be an ideal replacement.

What I'm thinking is that the Navy decides to replace the engine in the F-4 at the same time that they are developing the F401 engine for the Tomcat. Using the same core and as many common parts as possible to cut costs and reduce the logistics requirements (common spare parts pool). The actual engine would end up very similar to the OTL PW1120. Perhaps designated as the F401-PW-200 to try and sell it to Congress as a derivative of the engine in the Tomcat?
 
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Archibald

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Why not try the J101 ? F404 direct ancestor, must be available in the early 70's since it was related to the P.530 Cobra (also Hornet direct ancestor). Compact, fuel efficient.

I suppose this Phantom upgrade thing is related to the (seemingly untractable) issue of having an interceptor for the Essex after the Crusaders get eaten by Vietnam...?

With Vought unable to upgrade the Crusader byond the -J; or turn the A-7 back into a... Crusader (ROTFL)
...
I readily agree the most reasonable option would be to upgrade the Phantom fleet, one way or another. Basically, the Phantom fleet will ride together with the Essex until the late 80's; and together with... the soviet Union and Cold War, they will all die by 1990.
 

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Not quite as intractable as it seems. The Phantom was trialed on the Intrepid in 1960 with the trials being considered satisfactory. During Vietnam, an F-4J had to divert to Bon Homme Richard while training off the California coast because they ran low on fuel. No special conditions or requirements were needed to either recover or launch the aircraft.

Plus, with an engine like the F401, it lets the Phantom do some very interesting things. Like super cruise and go supersonic while climbing straight up.

And yes, this is mainly to serve as a way to keep a viable fleet air defense Interceptor on the Essex. But not necessarily because the Crusader is getting eaten alive.
 

elmayerle

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A cropped-fan version of the F401, much as the PW1120 is essentially a cropped-fan version of the F100 might work. Dimensionally, you would probably end up with the same diameter as the PW1120 in order to do a "fit and function" replacement for the J79. The F401 was, IIRC, roughly two inches greater in diameter than the F100 but the cores were quite similar, both deriving from the basic JTF22 design. A full-sized F401 would be, again IIRC, something near a foot greater in diameter than the J79 and would never work.

Mind you, the F401 had it's problems, two of them brought back from the test stands in bushel baskets in a one week time period does not help to sell the engine. I will say that, if they had to cancel the F401, they should have then proceeded with the developed TF41 variants that Allison had already demonstrated in 1967. Beyond that, let me say that the crusade to cancel the F401 on the grounds that "the TF30 is good enough" left a profound distaste for the pol that led it; particularly when, five years later, the USN was having a lot of problems with the TF30, he pronounced "The Navy bought Turkey, not a Tomcat." with no acknowledgement of his part in their difficulties. This man went on to be Bill CLinton's first Secretary of Defense and was Les Aspin.
 

_Del_

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Why not just add an afterburner to the TF41? It's a bit slimmer than the original Spey which was already shoehorned into the Phantom. It's already onboard with the A-7's from the 60's on, and development cost should be relatively small. Wouldn't exactly be revolutionary for the Phantom, but it should cut fuel burn, extend range or time on station, and give a higher max thrust on take off than the J79.

ETA: I like the plausibility of a slimmed down engine using the TF30 core, but the afterburning TF41 gets you away from the TF30 debacle, and it seems like a quick, cheap development. Plus, it opens up possibilities for the A-7.
 
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zen

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All this to avoid the F4k?
I don't think the TF41 was that much different from the Spey?
Reheat chambers tend to a larger diameter than the engine.
 

Archibald

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Nope, the "British Spey Phantom / TF41 connection" won't work here. AFAIK the author just want to upgrade second-hand Phantoms from the USN.
I mean, trying to put TF41 / Speys in them would not be possible unless a British Phantom massive rebuild, that is, brand new aircraft.

What the author wants is to replace the USN Phantoms J79s by an engine of dimensions close enough, no massive rebuild of these second-hand airframes is necessary. TF41 / Spey can't do that.
By contrast, PW1120 was specifically created for the job.

I suggested J101 because I know it is the "smaller turbofan" category. Don't forget, J101 was linked to P.530, itself the "true heir" of the F-5 that had pioneered used of "very small engines" - the J85.

Hey, RB.172 or RB.199 (RR equivalent to the J101 / F404 family) might also be possible.
 

Archibald

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"Airframe surgery" - spot on. Not sure if it is desirable here.

Elmayerle nailed it pretty well.

A cropped-fan version of the F401, much as the PW1120 is essentially a cropped-fan version of the F100 might work. Dimensionally, you would probably end up with the same diameter as the PW1120 in order to do a "fit and function" replacement for the J79. The F401 was, IIRC, roughly two inches greater in diameter than the F100 but the cores were quite similar, both deriving from the basic JTF22 design. A full-sized F401 would be, again IIRC, something near a foot greater in diameter than the J79 and would never work.
 

zen

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It seems that RR might have had a scaled up RB.199 concept at some point.....approximately Spey sized.
Certainly possible.
Or....turn this around for the French for once. What about an M53 version?
Could SNECMA do a deal with a US engine supplier for licensing?
 

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Why not just add an afterburner to the TF41? It's a bit slimmer than the original Spey which was already shoehorned into the Phantom. It's already onboard with the A-7's from the 60's on, and development cost should be relatively small. Wouldn't exactly be revolutionary for the Phantom, but it should cut fuel burn, extend range or time on station, and give a higher max thrust on take off than the J79.

ETA: I like the plausibility of a slimmed down engine using the TF30 core, but the afterburning TF41 gets you away from the TF30 debacle, and it seems like a quick, cheap development. Plus, it opens up possibilities for the A-7.
It's not slim enough. McDonnell Douglas went through hell trying to shoehorn the Spey into the Phantom. By the time they finally got it to fit, the British Phantoms were practically a different aircraft. I'm thinking something more along the lines of a relatively low cost option.
 

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Nope, the "British Spey Phantom / TF41 connection" won't work here. AFAIK the author just want to upgrade second-hand Phantoms from the USN.
I mean, trying to put TF41 / Speys in them would not be possible unless a British Phantom massive rebuild, that is, brand new aircraft.

What the author wants is to replace the USN Phantoms J79s by an engine of dimensions close enough, no massive rebuild of these second-hand airframes is necessary. TF41 / Spey can't do that.
By contrast, PW1120 was specifically created for the job.

I suggested J101 because I know it is the "smaller turbofan" category. Don't forget, J101 was linked to P.530, itself the "true heir" of the F-5 that had pioneered used of "very small engines" - the J85.

Hey, RB.172 or RB.199 (RR equivalent to the J101 / F404 family) might also be possible.
Exactly this. I'm not looking for the Navy to buy more new aircraft, but for the Phantom to have a somewhat low cost engine upgrade to keep them viable through the last 15 or so years of their service. That's why I was thinking of something like a cropped fan version of the F401. Have the Navy not abandon it, and now you've got a much better powerplant for the Tomcat and a common spare parts pool for the -14 and the Phantom (for engines anyway).
 

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More seriously: the 80's will be interesting, to say the least. With the F-14B alive and kicking, if it ever pulls an OTL F-14D, then no real need for the A-6F as a big strike platform... in turn, this ricochet on the A-12 Flying Dorito, Superbug and F-35 early pre-history...
The Hornet probably still happen, but the very existence of a "decent" F-14, plus upgraded Phantoms (same engine) plus the AV-8B start to REALLY hurt, particularly in the 1978-81 timeframe when the F-18 debate greatly heated up... (someday I will read "the Pentagon paradox". Someday...)
 

riggerrob

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WI some second-world F-4 user (Australia, Greece, Iran, Israel, Japan, South Korea, Spain, Turkey, West Germany, UK, etc.) runs a fowl of USA politics, so has to search elsewhere for replacement engines?

The first parallel project that comes to mind was the Israeli project to re-engine Mirage III with American engines.
Israel helped South Africa upgrade their Mirages too.
At one point, South Africa studied installing Russia-built Klimov RD-33 engines in their Cheetah/Mirages!
 
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SSgtC

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More seriously: the 80's will be interesting, to say the least. With the F-14B alive and kicking, if it ever pulls an OTL F-14D, then no real need for the A-6F as a big strike platform... in turn, this ricochet on the A-12 Flying Dorito, Superbug and F-35 early pre-history...
The Hornet probably still happen, but the very existence of a "decent" F-14, plus upgraded Phantoms (same engine) plus the AV-8B start to REALLY hurt, particularly in the 1978-81 timeframe when the F-18 debate greatly heated up... (someday I will read "the Pentagon paradox". Someday...)
That's kind of the idea. Even with an engine upgrade, the Phantom will not be long for US service. And the Hornet will still happen. The Corsair still needs to be replaced and the Phantom is still essentially a 1950s aircraft with the newest airframes being built in the early 70s
 

A Tentative Fleet Plan

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WI some second-world F-4 user (Australia, Greece, Iran, Israel, Japan, South Korea, Spain, Turkey, West Germany, UK, etc.) runs a fowl of USA politics, so has to search elsewhere for replacement engines?

The first parallel project that comes to mind was the Israeli project to re-engine Mirage III with American engines.
Israel helped South Africa upgrade their Mirages too.
At one point, South Africa studied installing Russia-built Klimov RD-33 engines in their Cheetah/Mirages!
Given that the Second World was the Soviet Union and its allies, I would hope that no Second World country would have a large fleet of Phantoms to re-engine in the first place.
 

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All this to avoid the F4k?
I don't think the TF41 was that much different from the Spey?
Reheat chambers tend to a larger diameter than the engine.
IIRC, the TF41 is larger than the Spey used by the F-4K et al. The Spey in the Phantom is based on what, in civil use, was labelled the Spey Jr. while the TF41 is based on the larger version of the Spey.
 

Apophenia

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IIRC, the TF41 is larger than the Spey used by the F-4K et al. The Spey in the Phantom is based on what, in civil use, was labelled the Spey Jr. while the TF41 is based on the larger version of the Spey.

Evan: The engines for British Phantoms were RB.168-15R Spey 201s - effectively reheat versions of the engines of the Buccaneer S.2. The RB.163 was the civil equivalent to the military RB.168. The smaller-diameter Spey Junior - RB.183, later renamed Tay - was a scaled-down civil RB.163.
 

_Del_

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Why not just add an afterburner to the TF41?
It's not slim enough. McDonnell Douglas went through hell trying to shoehorn the Spey into the Phantom. By the time they finally got it to fit, the British Phantoms were practically a different aircraft. I'm thinking something more along the lines of a relatively low cost option.
Well, TF30 and F100 development were both near -disastrous in the timeframe; I'm not sure a derivative of those cores is the most plausible course for success, but it arguably makes decent sense at the time without the advantage of hindsight.
 

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Why not just add an afterburner to the TF41?
It's not slim enough. McDonnell Douglas went through hell trying to shoehorn the Spey into the Phantom. By the time they finally got it to fit, the British Phantoms were practically a different aircraft. I'm thinking something more along the lines of a relatively low cost option.
Well, TF30 and F100 development were both near -disastrous in the timeframe; I'm not sure a derivative of those cores is the most plausible course for success, but it arguably makes decent sense at the time without the advantage of hindsight.
That's actually kinda what I'm aiming for. That it makes sense at the time. For the TL I'm writing, I'm trying to avoid using hindsight. For instance, we know that the Cold War will be over by 89. But in the TL, they don't. So while we may not bother upgrading older aircraft, it could be seen as useful by people at that time.
 

_Del_

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I agree, but the most realistic consequence of that decision would be a new engine built around a trouble plagued core. It's hard to see either engine producing a super Phantom before the early- or mid-80's when the problems are ironed out. Also hard to imagine there's an appetite for derivatives of engines plagued with development problems. It'd have to be an early decision to co-develop the core and two engines. And as a simple reengining proposal, it seems unlikely to have the necessary juice to survive that uphill battle, imo. F404 isn't available until roughly the same time frame as the TF30 and F100 starts getting sorted.

On the otherhand, the RN already kindly paid big money in the 60's to develop a less sexy Phantom to operate from smaller carriers with weaker cats, which uses (more or less) an engine already in the fleet Corsairs and has better range/endurance than the USN version. If the Navy developed an interest in regularly operating their F-4's from short decks for whatever reason and are willing to sacrifice a bit of performance for increased range and endurance (also opens up cross decking opportunities with the RN carriers), then maybe they start buying them as early as the sixties. Would also drive some of the costs for the UK down which maybe results in an increased buy for the RN as well.

Love the Phantom, so it's fun wondering, but honestly by the time the F-14 is past it's teething problems, it's hard to make the case for keeping the F-4 onboard in large numbers. A-6 provides true strike ability. F-14 for fleet air defense. Then a mash of types competing for deckspace and money. F-4 is a very expensive swing option with the A-7 and A-4's hauling tonnage much, much cheaper. It makes me wonder if adding an afterburner to the TF41 and installing an AN/APG-66 wouldn't make the A-7 "good enough" as a low cost supplement to strike and counter air. Then the push for a "Hornet" to replace them gets pushed down the timeline a bit and far better engine options are available.

It's fun to think about. Hope you figure out your best option :)
 

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I'm currently writing an alternate history timeline of the Cold War with a focus on the Essex class carriers. In the TL, they will be serving in the Attack role through the 1980s due to various reasons including a more unstable world and the need for a larger carrier fleet. As a result of events in the TL, the Navy will be putting Phantoms on those ships (it is technically feasible, they were trialed on Intrepid in 1960). So I'm basically looking for ways to keep the F-4 fleet viable longer, but at as low a cost as possible. And reengining them is the easiest way to do this (it also makes operation of the smaller Essex class far easier with a lot more thrust to get off the deck).

That's also why I'm looking for an early to mid 70s timeframe. Past that and the class won't be in service long enough to make it cost effective. Otherwise I'd say they should just drop in an F404 and call it a day (the J79 and F404 are remarkably similar with the F404 being shorter and lighter).
A question I haven't seen asked: when does your timeline diverge? That makes a difference in terms of what is available, not just in terms of engines, but Essexes as well. Mid 70s would mean less ships, F404s as a possibility, as would be conformal weapons carriage, fly by wire, and canards, all of which were tested in the early 70s. Mid 60s would mean more ships, but also the potential for something like the proposed F-4 high lift, with bigger wings and lower landing and take off speeds as well as longer range due to new GE turbofans (that I believe lost to the F100). Mid 50s would mean all the Essexes could get angled decks, the RB106 could be in play, as would things like Supertigers and Crusader III.

Secondy, do you have any data on the spotting factor of the F-8 vs. the F-4? The Phantom is 9 feet longer and a lot heavier. It might be it was rejected for service from the Essex class because of spot factor and weight reasons reducing the size of the Air Wing too much, and any such considerations would still apply.
 

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I'm currently writing an alternate history timeline of the Cold War with a focus on the Essex class carriers. In the TL, they will be serving in the Attack role through the 1980s due to various reasons including a more unstable world and the need for a larger carrier fleet. As a result of events in the TL, the Navy will be putting Phantoms on those ships (it is technically feasible, they were trialed on Intrepid in 1960). So I'm basically looking for ways to keep the F-4 fleet viable longer, but at as low a cost as possible. And reengining them is the easiest way to do this (it also makes operation of the smaller Essex class far easier with a lot more thrust to get off the deck).

That's also why I'm looking for an early to mid 70s timeframe. Past that and the class won't be in service long enough to make it cost effective. Otherwise I'd say they should just drop in an F404 and call it a day (the J79 and F404 are remarkably similar with the F404 being shorter and lighter).
A question I haven't seen asked: when does your timeline diverge? That makes a difference in terms of what is available, not just in terms of engines, but Essexes as well. Mid 70s would mean less ships, F404s as a possibility, as would be conformal weapons carriage, fly by wire, and canards, all of which were tested in the early 70s. Mid 60s would mean more ships, but also the potential for something like the proposed F-4 high lift, with bigger wings and lower landing and take off speeds as well as longer range due to new GE turbofans (that I believe lost to the F100). Mid 50s would mean all the Essexes could get angled decks, the RB106 could be in play, as would things like Supertigers and Crusader III.

Secondy, do you have any data on the spotting factor of the F-8 vs. the F-4? The Phantom is 9 feet longer and a lot heavier. It might be it was rejected for service from the Essex class because of spot factor and weight reasons reducing the size of the Air Wing too much, and any such considerations would still apply.
The POD is in April, 1957. And yes, I have the spot factor numbers for the Phantom. With the A-4 equalling Spot Factor 1, a Phantom has a spot factor of 1.86 while a Crusader is at 1.46. Over on AH.com, we had a very lengthy discussion about spot factors and air wing size. In the end, we figured that an air wing assigned to an Essex class could reasonably embark 24xF-4s, 24xA-7s, 4xE-1s (or later E-2s) and 4xEKA-3s. As newer aircraft are introduced you can swap out the four Skywarriors for eight Prowlers and KA-6s and actually gain space (the whale is a huge plane).

In OTL, the trials on Intrepid were considered successful. But the Navy choose not to operate them from the Essex class for a few reasons:

1. They were fuel and ammo hogs and the Essex class had limited aviation stores space.

2. They had plenty of Crusaders in service and made the not unreasonable decision to simply keep them on the Essex class (since they were smaller and used less fuel and ordinance) while the Phantom was assigned to the bigger decks.

3. Politics. The Navy wanted more Super Carriers. And a big argument for them was that the Essex class were just too small to operate the Phantom and Intruder from. (Neither claim was actually strictly speaking true. Both aircraft could operate from the class, it would just require more frequent UNREPs.)
 
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SSgtC

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I agree, but the most realistic consequence of that decision would be a new engine built around a trouble plagued core. It's hard to see either engine producing a super Phantom before the early- or mid-80's when the problems are ironed out. Also hard to imagine there's an appetite for derivatives of engines plagued with development problems. It'd have to be an early decision to co-develop the core and two engines. And as a simple reengining proposal, it seems unlikely to have the necessary juice to survive that uphill battle, imo. F404 isn't available until roughly the same time frame as the TF30 and F100 starts getting sorted.

On the otherhand, the RN already kindly paid big money in the 60's to develop a less sexy Phantom to operate from smaller carriers with weaker cats, which uses (more or less) an engine already in the fleet Corsairs and has better range/endurance than the USN version. If the Navy developed an interest in regularly operating their F-4's from short decks for whatever reason and are willing to sacrifice a bit of performance for increased range and endurance (also opens up cross decking opportunities with the RN carriers), then maybe they start buying them as early as the sixties. Would also drive some of the costs for the UK down which maybe results in an increased buy for the RN as well.

Love the Phantom, so it's fun wondering, but honestly by the time the F-14 is past it's teething problems, it's hard to make the case for keeping the F-4 onboard in large numbers. A-6 provides true strike ability. F-14 for fleet air defense. Then a mash of types competing for deckspace and money. F-4 is a very expensive swing option with the A-7 and A-4's hauling tonnage much, much cheaper. It makes me wonder if adding an afterburner to the TF41 and installing an AN/APG-66 wouldn't make the A-7 "good enough" as a low cost supplement to strike and counter air. Then the push for a "Hornet" to replace them gets pushed down the timeline a bit and far better engine options are available.

It's fun to think about. Hope you figure out your best option :)
Here's the thing, the USN already knew what mods would be needed to fly fully loaded Phantoms off an Essex as early as 1962. They proposed it to Australia when the RAN was considering buying Philippine Sea. What they proposed was essentially an F-4K without the BLC system or Spey.

As for the Air Wing, I agree completely. On the bigger decks, once the Tomcat starts showing up, there's no need for the Phantom. But neither the Midway or Essex class could operate F-14s (their hangers weren't tall enough). I'm looking at the Navy keeping the Phantom strictly for the smaller decks. In the TL I'm working on, the Navy will be planning on having at least 6 carriers flying Phantoms though the 80s. So that's a dozen VF squadrons with F-4s. That's a big enough program to justify a "common" engine with the F-14B.
 

overscan (PaulMM)

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F401 was essentially an F100 core with an enlarged fan section, so what you are after is an F100 with a reduced fan section, which is basically the PW.1120, but much earlier.

There's no technical reason why this couldn't happen, but I would go a different route.

How about GE, about 1970, smarting from the loss of both F100 and F401 contracts with their GE1/10, don't invest in J101 for Northrop P-530, but instead design a GE1/10 derivative with smaller fan, compatible with J-79 installation. This wins a contract for Phantom reengining, and is very successful with the Navy and even sells abroad, leading to GE proposing and winning a development of this engine for the F-14B to replace the troubled F401.
 

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