F-4 Phantom engine upgrade

[isayyo2]

A twin J75 anything would be a beast of an aircraft, look at the Arrow, XF-108, or Tu-128 and compare it to the Phantom. Heck I think there were J75 and J58 A-5 Vigilante variants conjured up for the Air Force. How big would a carrier need to be two host two Vigilante sized VF squadrons in addition to the other 50+ planes of the air wing? Suezmax CVN?

 

[sferrin]

Would a pair of J75s have been too big? I seem to recall an F-101 configuration looked at with that configuration.

For the F-4? Yeah, way too big. The J75 had a 50.4" diameter and was 252" long. The J79 was over a foot narrower at 38.3" diameter and nearly four feet shorter at 207.3". But that's too be expected when the J75 developed damn near as much thrust at Military Power (16,500 pounds) as the J79 did in afterburner (17,000 pounds).

Makes me wonder how they were planning to stuff them into an F-101.

 

[SSgtC]

Would a pair of J75s have been too big? I seem to recall an F-101 configuration looked at with that configuration.

For the F-4? Yeah, way too big. The J75 had a 50.4" diameter and was 252" long. The J79 was over a foot narrower at 38.3" diameter and nearly four feet shorter at 207.3". But that's too be expected when the J75 developed damn near as much thrust at Military Power (16,500 pounds) as the J79 did in afterburner (17,000 pounds).

Makes me wonder how they were planning to stuff them into an F-101.

No idea. The J57s in the F-101 were 40.3" in diameter and 211" long. There was a proposal to fit J79s in the Voodoo. That one even flew. Could you be thinking of that one maybe?

 

[Archibald]

Folks,

J57 and J75 were half-brothers, same size, same weight overall. Whatever aircraft that started with J57s, could (on paper at least) upgrade to J75s.
On the contrary, the J79 was 1-3rd smaller and lighter, kind of F404 to F110. Any aircraft designed around J79 engine bays wasn't taking any J75 without huge mods.
And on the contrary of the contrary - whatever engine bay designed for a massive J57 / J75 could easily take a smaller J79...

 

[sferrin]

Would a pair of J75s have been too big? I seem to recall an F-101 configuration looked at with that configuration.

For the F-4? Yeah, way too big. The J75 had a 50.4" diameter and was 252" long. The J79 was over a foot narrower at 38.3" diameter and nearly four feet shorter at 207.3". But that's too be expected when the J75 developed damn near as much thrust at Military Power (16,500 pounds) as the J79 did in afterburner (17,000 pounds).

Makes me wonder how they were planning to stuff them into an F-101.

No idea. The J57s in the F-101 were 40.3" in diameter and 211" long. There was a proposal to fit J79s in the Voodoo. That one even flew. Could you be thinking of that one maybe?

I'll have to double-check. I know there have been some crazy ideas over the years (an F-102 with a pair of J79s for instance). Some got further than others. We're not talking hardware but internal company concepts.

 

[sferrin]

Looks like this might be where I saw it:

https://www.secretprojects.co.uk/threads/j57-derivatives-for-f-101.13929/#post-165674

 

[CV12Hornet]

A twin J75 anything would be a beast of an aircraft, look at the Arrow, XF-108, or Tu-128 and compare it to the Phantom. Heck I think there were J75 and J58 A-5 Vigilante variants conjured up for the Air Force. How big would a carrier need to be two host two Vigilante sized VF squadrons in addition to the other 50+ planes of the air wing? Suezmax CVN?

Something with 12 Intruders + 24 Corsairs + 4 Hawkeyes, Prowlers, and tankers + 10 S-3 Vikings + 3 recon Vigilantes would likely need to be 1200 feet long and proportioned in beam and draft to match.

Vigilantes are big.

 

[isayyo2]

A twin J75 anything would be a beast of an aircraft, look at the Arrow, XF-108, or Tu-128 and compare it to the Phantom. Heck I think there were J75 and J58 A-5 Vigilante variants conjured up for the Air Force. How big would a carrier need to be two host two Vigilante sized VF squadrons in addition to the other 50+ planes of the air wing? Suezmax CVN?

Something with 12 Intruders + 24 Corsairs + 4 Hawkeyes, Prowlers, and tankers + 10 S-3 Vikings + 3 recon Vigilantes would likely need to be 1200 feet long and proportioned in beam and draft to match.

Vigilantes are big.

Now we’re talking! Might as well add some Talos or SM-1ER launchers while you at it; or perhaps with an active roll stabilizer double hangers could come back in fashion?

 

[CV12Hornet]

A twin J75 anything would be a beast of an aircraft, look at the Arrow, XF-108, or Tu-128 and compare it to the Phantom. Heck I think there were J75 and J58 A-5 Vigilante variants conjured up for the Air Force. How big would a carrier need to be two host two Vigilante sized VF squadrons in addition to the other 50+ planes of the air wing? Suezmax CVN?

Something with 12 Intruders + 24 Corsairs + 4 Hawkeyes, Prowlers, and tankers + 10 S-3 Vikings + 3 recon Vigilantes would likely need to be 1200 feet long and proportioned in beam and draft to match.

Vigilantes are big.

Now we’re talking! Might as well add some Talos or SM-1ER launchers while you at it; or perhaps with an active roll stabilizer double hangers could come back in fashion?

If you're going double hangers you can make the overall ship smaller, so I don't think you want that. Talos is too big, but a couple of Terrier/Standard ER launchers is perfectly doable. It was done on the Kitty Hawks, after all.

 

[isayyo2]

A twin J75 anything would be a beast of an aircraft, look at the Arrow, XF-108, or Tu-128 and compare it to the Phantom. Heck I think there were J75 and J58 A-5 Vigilante variants conjured up for the Air Force. How big would a carrier need to be two host two Vigilante sized VF squadrons in addition to the other 50+ planes of the air wing? Suezmax CVN?

Something with 12 Intruders + 24 Corsairs + 4 Hawkeyes, Prowlers, and tankers + 10 S-3 Vikings + 3 recon Vigilantes would likely need to be 1200 feet long and proportioned in beam and draft to match.

Vigilantes are big.

Now we’re talking! Might as well add some Talos or SM-1ER launchers while you at it; or perhaps with an active roll stabilizer double hangers could come back in fashion?

If you're going double hangers you can make the overall ship smaller, so I don't think you want that. Talos is too big, but a couple of Terrier/Standard ER launchers is perfectly doable. It was done on the Kitty Hawks, after all.

And Enterprise was designed with them at some point too I think, but they were cut to save costs.

 

[Scotty2]

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?

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.

In the late 70's they changed out the engines on the F4G's to a smokeless engine, it was still a J79. It took a while to figure it out. I changed out engines everyday, in or out for 18 months or so till they figured out how to eliminate the smoke in the cockpit, with the new engines. Finally they figured it out and the engines worked. Although when the GE rep said, thats what the navy determined. I almost got sent to Leavenworth, cause I was on my way to beating the tar out of him for wasting a year of work. Thanks Tim for stopping me.
This made a huge difference in the amount of smoke they produced. Now you can't follow them for a half hour from the smoke trail.

 

[Pioneer]

So, can I ask why the USN wouldn't just settle on a 'marinised' derivative of the F100 turbofan?, what with the money, risk and tine it stood to save...

Regards
Pioneer

 

[kaiserd]

The US Navy in a sense did look to adopt a marinised F100 (as noted above the F401 was derived from the F100).

The US Navy had heavier aircraft in mind than the airforce (the F-14 versus the F-15, what emerged as the F-16 for the airforce versus whatever would emerge for the US Navy to complement the F-14 - though the US Navy eventually went down the twin engined F/A-18 path instead - competing navalised F-16 derivative designs featured the F401 for “full performance” variants), together with more generally recognising there was always likely to be a weight penalty for naval/ carrier compatibility.

Hence the US Navy would likely have seen themselves as needing more powerful engines than their Airforce equivalents to deliver similar performance.
Again using the navalised F-16 derivative designs as illustration - there were “minimum performance” designs with the F100 engine but they suffered in comparison with the performance of their US airforces equivalent and in comparison with the projected performance of the F401 engined navalised F-16 derivative designs.

 

[Pioneer]

The US Navy in a sense did look to adopt a marinised F100 (as noted above the F401 was derived from the F100).

The US Navy had heavier aircraft in mind than the airforce (the F-14 versus the F-15, what emerged as the F-16 for the airforce versus whatever would emerge for the US Navy to complement the F-14 - though the US Navy eventually went down the twin engined F/A-18 path instead - competing navalised F-16 derivative designs featured the F401 for “full performance” variants), together with more generally recognising there was always likely to be a weight penalty for naval/ carrier compatibility.

Hence the US Navy would likely have seen themselves as needing more powerful engines than their Airforce equivalents to deliver similar performance.
Again using the navalised F-16 derivative designs as illustration - there were “minimum performance” designs with the F100 engine but they suffered in comparison with the performance of their US airforces equivalent and in comparison with the projected performance of the F401 engined navalised F-16 derivative designs.

Thanks for your informative response kaiserd .
I still can't help think, like most jet engines the USN adopted, their initial dry/afterburn engines would develop into more powerful, more refined engines - the marinised F100 being no different.....

Regards
Pioneer