Alternative AAM history: AIM-4H enters service.

Hit rates for AIM-4 was also tainted by ripple-fire use, yes or no?

And wasn't part of the F-4's Tiger Eye tied to AIM-4's compatibility?
 
SOC said:
Yes, it was wholly unsuited for the anti-fighter mission, and yes, there were several limitations, such as the pre-firing sequence being complex and time-consuming.
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Well, the AIM-4 family was designed for the planes with automatic fire control system; not for largerly-manual Phantom. The idea was, that all those complex procedures would be handled by automatic before launch - as soon as radar/FLIR got target lock - and by the time of coming in range, the missile is already locked and ready.
 
Dilandu said:
Well, the AIM-4 family was designed for the planes with automatic fire control system; not for largerly-manual Phantom. The idea was, that all those complex procedures would be handled by automatic before launch - as soon as radar/FLIR got target lock - and by the time of coming in range, the missile is already locked and ready.
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The biggest problem is that the AIM4 was designed around basically non-maneuvering targets, so only having 2min to get the IR seeker locked on and launched wasn't an issue.

But that's a really big disadvantage when you're trying to get the AIM4 to lock onto a maneuvering fighter!

Not sure as to the ease of Liquid Nitrogen coolant versus Liquid Argon coolant. Obviously lots more nitrogen in the atmosphere than argon (which makes LN2 a lot cheaper), and their boiling points are within 11degC of each other. Both are pretty deep cryogenics, LAr is 88K while LN2 is 77K. Wiki says that the primary reason to use Argon is when Nitrogen is too reactive with whatever you're doing.

Anyone know why the USN used Argon coolant for the early Sidewinders? It seems like the much more expensive option. Oh, nevermind, the USN used gaseous argon, not liquid! So it was a high pressure bottle, not a dewar (which holds less volume of materials inside for an equal external volume). LN2 has about a 700:1 expansion ratio from liquid to gas, so it's got about 3x the expansion compared to gaseous argon at 230bar.
 
Scott Kenny said:
The biggest problem is that the AIM4 was designed around basically non-maneuvering targets, so only having 2min to get the IR seeker locked on and launched wasn't an issue.
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Well, not exactly. The idea was, that seeker is pre-locked while missile is still inside the weapin bay. I remind you, that most of Falcons were designed for internal carriage; AIM-4D was an exception.

Basically, it worked like that. The interceptor start to track target with its own sensors well in advance. Fire control system feed the data about target to the missile, which spin its seeker and "lock on" the data feed. When interceptor came in range, the FCS would open weapon bay, lower the missile launcher and shot the missile - which would be already "tracking" the target and would just switch from external data feed to its own sensor.

So it would work fine against fighters too. The requirement is that interception must be started BVR, so by the time of actual attack, the missile would be ready.
 
The aim of this thread was to ask what would have happened if the AIM-4's biggest issues - reliability, operational issues, and the lack of a proximity fuze - had been tidied up, not to suggest that it was the best damn missile ever.

I would have proceeded with it, on the grounds that it would form the basis to supplement or supplant existing IR AIM-4s on Falcon-carrying aircraft - not only in US service but also Canadian (Voodoo), Swedish (Draken; Viggen to some extent), Swiss (Mirage IIIS), and Finnish service (Danish Drakens did not use the Falcon, and Austrian Drakens were forbidden from doing so by post-war treaties).
 
Scott Kenny said:
Yes, the Sparrow kept getting heavier and heavier warheads to make up for the poor terminal guidance.

The US also kept the F106, armed with AIM4s, flying into the 1980s.
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The Sparrow eventually evolved into a highly successful missile (a significant number of Gulf War kills before the AMRAAM entered service as its replacement).

The AIM4 and F-106 were kept in service because, until the threat of cruise missile armed bombers (Bear H’s and Blackjacks) emerged as a real threat, they were undertaking a still relatively significant but a relatively undemanding and at least partially token role so no one wanted to spend any real money on it (before these bombers the Soviet strategic bomber force able and tasked to attack the US was old, tiny and itself rather token). And by the time this modern cruise missile armed bomber threat manifested relatively plentiful F-4s plus some F-15s and F-16s were available to replace the F-106.

The AIM-4 and F-106 were “good enough” for the threats they were facing for most of their service lives. It’s just that both they and their threats were both each a bit of a back-water relic of rapid opposing bomber and interceptor development that ICBMs had brought an effective end to (and which “modern” Tomahawk-equivalent ALCMs and AS-15/ KH-55 cruise missile armed bombers brought some life back into, at least for the late Cold War period).

One of the many reasons why arguments for the F-12 being bought/ entering service are so misconceived.
 
I believe the AIM-4E/F/G variants used by the F-106 were improved over the earlier versions. The AIM-4D used the guidance system of the later IR-guided models but used the smaller airframe and everything else of the earlier variants. I can't say for sure but I imagine those later AIM-4s would have been effective against the sort of bomber-sized targets they were intended to be used against.

The AIM-4H would have resolved several of the major problems the AIM-4D had engaging fighter-sized targets. But improvements into the AIM-9 Sidewinder series were also well-underway and the Sidewinder was also being used on all sorts of earlier USAF aircraft (F-100, F-104, F-105, and more) while the Falcon was limited to the interceptors and the F-4D.

If you wanted to make the F-106 more useful you could have probably incorporated the laser proximity fuze and other improvements of the XAIM-4H into the Falcon variants used by The Six but the USAF had all sorts of different priorities in those years. The entire USAF interceptor program had been badly damaged by the conflict with McNamara (F-111 or nothing) and the F-X (F-15) program required most of the funding. There was also a reassessment of the Soviet bomber threat versus that of their ICBMs and directly countering those bombers seemed less important than it had been in the past.

I love the F-106 and think it would have been great if it did get some further upgrades during its career, but there is always so much the money is never there for. Just consider some of the weapon systems and components for the F-15 that got the axe due to the eternal war with Congress and the other services/DoD for funding.
 
kaiserd said:
The Sparrow eventually evolved into a highly successful missile (a significant number of Gulf War kills before the AMRAAM entered service as its replacement).

The AIM4 and F-106 were kept in service because, until the threat of cruise missile armed bombers (Bear H’s and Blackjacks) emerged as a real threat, they were undertaking a still relatively significant but a relatively undemanding and at least partially token role so no one wanted to spend any real money on it (before these bombers the Soviet strategic bomber force able and tasked to attack the US was old, tiny and itself rather token). And by the time this modern cruise missile armed bomber threat manifested relatively plentiful F-4s plus some F-15s and F-16s were available to replace the F-106.

The AIM-4 and F-106 were “good enough” for the threats they were facing for most of their service lives. It’s just that both they and their threats were both each a bit of a back-water relic of rapid opposing bomber and interceptor development that ICBMs had brought an effective end to (and which “modern” Tomahawk-equivalent ALCMs and AS-15/ KH-55 cruise missile armed bombers brought some life back into, at least for the late Cold War period).

One of the many reasons why arguments for the F-12 being bought/ entering service are so misconceived.
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I like your analogy kaiserd.
I've always been somewhat dubious of the USAF's seeming delibrate exaggeration of 'Soviet Strategic Bomber capabilities', as you rightfully state - 'till the advent of the threat of cruise missile armed bombers (Bear H’s and Blackjacks) emerged as a real threat.'
But I guess with the competitive nature of the Tri-Service for budget allocation and of course the engrained post-military career Military Industrial Complex, it inevitably becomes a perpetuating system.

Regards
Pioneer
 
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kaiserd said:
The Sparrow eventually evolved into a highly successful missile (a significant number of Gulf War kills before the AMRAAM entered service as its replacement).
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It did. Just took some time.

But if you compare the development paths of Sparrow to Skyflash or Aspide, Sparrow got bigger warheads and then got better seekers, when Skyflash and Aspide went to better seekers immediately.

AIM-7A (-B was the ARH Sparrow 2) had a 20kg warhead. AIM-7C, -D, and -E went to a 30kg continuous-rod warhead. 1976's AIM-7F got fully solid-state electronics, but didn't improve the accuracy of the seeker of the -E. Instead the -F got another +9kg of warhead weight (39kg total), and it wasn't until the AIM-7M that Sparrow got a Monopulse seeker, in 1982 (and bumped the warhead up to fully 40kg of blast-frag instead of the earlier continuous rod design).

Aspide was introduced in ~1973 with a lot of revisions and most importantly a Selenia inverse-monopulse seeker (on a 35kg warhead).

Skyflash was introduced in 1978 with a Marconi inverse-monopulse seeker.



kaiserd said:
The AIM4 and F-106 were kept in service because, until the threat of cruise missile armed bombers (Bear H’s and Blackjacks) emerged as a real threat, they were undertaking a still relatively significant but a relatively undemanding and at least partially token role so no one wanted to spend any real money on it (before these bombers the Soviet strategic bomber force able and tasked to attack the US was old, tiny and itself rather token). And by the time this modern cruise missile armed bomber threat manifested relatively plentiful F-4s plus some F-15s and F-16s were available to replace the F-106.

The AIM-4 and F-106 were “good enough” for the threats they were facing for most of their service lives. It’s just that both they and their threats were both each a bit of a back-water relic of rapid opposing bomber and interceptor development that ICBMs had brought an effective end to (and which “modern” Tomahawk-equivalent ALCMs and AS-15/ KH-55 cruise missile armed bombers brought some life back into, at least for the late Cold War period).
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After severely pissing off Col Olds and leading him to order spare USN Sidewinder wiring harnesses to fit to all his F-4s, I think the chances of the USAF going back to Falcons on F-4s or any plane not designed around them instead of Sidewinders is close to zero.

Which basically leaves the old Century Series, and not even all of them. Just F-101, F-102, and F-106. The F-100, F-104, and F-105 were Sidewinder planes (courtesy of how Sidewinder was made as a guidance pack for a 5" Zuni rocket, it didn't need a whole lot of support hardware in the plane)!

I'm not sure how much improvements you could sell to other air forces that got Falcon planes, not if the USAF was basically giving up on the thing... Maybe the Canadians, if they were sharing missiles with ADC?


kaiserd said:
One of the many reasons why arguments for the F-12 being bought/ entering service are so misconceived.
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I would like to hear your thoughts on that, but this thread isn't the place. Should we start a new one?
 
Scott Kenny said:
It did. Just took some time.

But if you compare the development paths of Sparrow to Skyflash or Aspide, Sparrow got bigger warheads and then got better seekers, when Skyflash and Aspide went to better seekers immediately.

AIM-7A (-B was the ARH Sparrow 2) had a 20kg warhead. AIM-7C, -D, and -E went to a 30kg continuous-rod warhead. 1976's AIM-7F got fully solid-state electronics, but didn't improve the accuracy of the seeker of the -E. Instead the -F got another +9kg of warhead weight (39kg total), and it wasn't until the AIM-7M that Sparrow got a Monopulse seeker, in 1982 (and bumped the warhead up to fully 40kg of blast-frag instead of the earlier continuous rod design).

Aspide was introduced in ~1973 with a lot of revisions and most importantly a Selenia inverse-monopulse seeker (on a 35kg warhead).

Skyflash was introduced in 1978 with a Marconi inverse-monopulse seeker.




After severely pissing off Col Olds and leading him to order spare USN Sidewinder wiring harnesses to fit to all his F-4s, I think the chances of the USAF going back to Falcons on F-4s or any plane not designed around them instead of Sidewinders is close to zero.

Which basically leaves the old Century Series, and not even all of them. Just F-101, F-102, and F-106. The F-100, F-104, and F-105 were Sidewinder planes (courtesy of how Sidewinder was made as a guidance pack for a 5" Zuni rocket, it didn't need a whole lot of support hardware in the plane)!

I'm not sure how much improvements you could sell to other air forces that got Falcon planes, not if the USAF was basically giving up on the thing... Maybe the Canadians, if they were sharing missiles with ADC?



I would like to hear your thoughts on that, but this thread isn't the place. Should we start a new one?
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F-106 was only 100 units, so no way to justify upgrades except by using COTS equipment. AIM-4 would not be one of those upgrades.
 
MadRat said:
F-106 was only 100 units, so no way to justify upgrades except by using COTS equipment. AIM-4 would not be one of those upgrades.
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?

There were 277x F106As made, plus 63x F106B trainers. And each F106 carried at least 2x Falcons and 1x Genie, so that is a minimum of 700 rounds to update, not counting any reloads.
 
Scott Kenny said:
?

There were 277x F106As made, plus 63x F106B trainers. And each F106 carried at least 2x Falcons and 1x Genie, so that is a minimum of 700 rounds to update, not counting any reloads.
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I think you mean two IR Falcons, but I get the point you're trying to make.

Plus the F-102, which was in US (ANG) service until 1976, and foreign customer service till 1979.
And the F-101 (US and Canadian).
And Swiss Mirages.
IIRC the Swedes licence-built any Falcons they used and provided their version of the missile to Draken customers, while upgrades to the IR version are alleged to match the -4H. So you possibly would not sell AIM-4H there.

Is there going to be an expanded suite of aircraft to which the missile is fitted? No. But the demand is there for fresh rounds in US service alone through to the late 1980s.
 
The AIM-4 only remained in service as the F-106 couldn't carry Sidewinders or Sparrow without major modifications.

AIM-4H was started in 1969 and made some test firings in 1970-1971. It was cancelled to save money. Nothing I've read suggests it was especially interesting, and with AIM-82, Agile, AIM-9K/L brewing it probably didn't make sense to fund it.
 
From what I understand XAIM-4H was supposed to have improved maneuverability and a laser proximity fuze, but the cooling system would still likely have been an issue unless it was completely redesigned. The F-106 was basically designed around the AIM-4 and couldn't fit Sidewinders in its weapons bay, at least not easily and not more than two of them. The only way to realistically upgrade an F-106's armament (aside from Six Shooter) would be to either make the AIM-4 better (XAIM-4H as-designed or better yet with the seeker of the AIM-9L), or mount Sidewinders on LAU-7 or LAU-105 rail launchers to the wing fuel tank pylons. Probably wouldn't have been too hard to do in conjunction with Six Shooter given that the F-106 apparently got a HUD out of that program, but without some sort of gunsight it would be hard to use AIM-9s from an F-106. Also wing launchers would negate the F-106's incredible speed to a certain extent (wouldn't be outrunning F-4s anymore :rolleyes:), but my suspicion is that the 106 fleet was close enough to the end of its life that the extra expense of adding AIM-9 capability just wasn't worthwhile, especially given the number of F-4s in service at the time.
 
Spino said:
or better yet with the seeker of the AIM-9L
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That didn't happen until the very late 1970s, so no.

That being said, I have seen an account of a pilot who, in an exercise, shot down a BOMARC with an AIM-4G head-on:
View: https://www.youtube.com/watch?v=jzi-SFqEScY
This is his own account, as a former F-106 pilot, and thus represents a primary source.

He refers to the AIM-4D as an older missile when in fact I've read that it was the final Falcon development, but the -4G seeker was placed into the body of one of the earlier variants, so this is probably why he says what he does.
 
pathology_doc said:
The aim of this thread was to ask what would have happened if the AIM-4's biggest issues - reliability, operational issues, and the lack of a proximity fuze - had been tidied up, not to suggest that it was the best damn missile ever.
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Well, if USAF have more freedom at least in modifications (not very likely under McNamara, but not impossible also), they may push for their own version of F-4 Phantom. Most likely with internal weapon bay for Falcon missiles (also to carry nuclear bombs semi-internally) and F-106 delivered fire control system.
 
Dilandu said:
Well, if USAF have more freedom at least in modifications (not very likely under McNamara, but not impossible also), they may push for their own version of F-4 Phantom. Most likely with internal weapon bay for Falcon missiles (also to carry nuclear bombs semi-internally) and F-106 delivered fire control system.
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All you get then is a repeat of what happened with the F-4K and M - a very much more expensive Phantom that doesn't do all that much more. I don't think there's room for this without such a major redesign that you almost have a different airplane. The money would better be spent on more F-106's.
 
pathology_doc said:
All you get then is a repeat of what happened with the F-4K and M - a very much more expensive Phantom that doesn't do all that much more. I don't think there's room for this without such a major redesign that you almost have a different airplane. The money would better be spent on more F-106's.
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Agreed. No point in modifying the F4.

Might get a modification of the F111B, however. Due to the Fleet Air Defense mission from TFX, the basic F111 airframe has pretty good loiter time for patrolling, as opposed to the fast climbing nature of the F106. The internal bay on the F111 should be able to hold at least 4x if not 6x AIM4, not counting what gets mounted under the wings (fuel tanks or more missiles or both, using pylons with shoulder rails like the F4 and F15 have). And that's without loading the Phoenix missiles, which the USAF saw as way too expensive. Nose is big enough to have a very big radar up front. ASG-18 or AWG9, take your pick. Remember, there were 3 radar lines across Canada to give early warning in time for the ADC interceptors to scramble, and then F111 Interceptors could act as AEW and controllers for F106s.

And of course there's updating all the F101/102/106 arsenal, plus everyone else using AIM4s for whatever planes they have.

Sparrow/Sidewinder was definitely the way forward, but there's no reason to abandon AIM4s outright (in comparison to AIM26/AIM47/AIM54)
 
Scott Kenny said:
The internal bay on the F111 should be able to hold at least 4x if not 6x AIM4, not counting what gets mounted under the wings
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IIRC it was designed to hold two Phoenix side by side.

According to Wikipedia, Phoenix is 3.9m long, 0.9m in span. Taking AIM-4D as roughly representative of the Falcon breed, we have a 2.02m length, 0.51m span. You might fit three Falcons abreast in the space of two Phoenix, but you won't fit two sets in tandem. The real difference is in the weight. Phoenix is right about the 1000lb mark, as befits an ultra-long-range Mach 5 missile from the transistor era; AIM-4D weighs 135lb, and the fractionally smaller AIM-4C only 119lb. Three AIM-4Ds weigh just a shade over 400lb, not even half as much as one Phoenix.

The other thing that fits in the F-111 internal bay is an M61 Gatling gun with over 2,000 rounds.
 
From what I've read about the Falcon series it sounds like the IR seeker wasn't bad, especially on the later variants including the AIM-4D. When functioning it probably could pick up a heat signature at longer ranges than the Sidewinders of the day could. But the cooling system enabling that caused all sorts of issues with timing. It would certainly be easy enough to intercept bombers with it, but in a dogfight scenario the time it would take to cool down the seeker and the limited time before it ran out of coolant resulted in many missed shots.

pathology_doc said:
IIRC it was designed to hold two Phoenix side by side.

According to Wikipedia, Phoenix is 3.9m long, 0.9m in span. Taking AIM-4D as roughly representative of the Falcon breed, we have a 2.02m length, 0.51m span. You might fit three Falcons abreast in the space of two Phoenix, but you won't fit two sets in tandem. The real difference is in the weight. Phoenix is right about the 1000lb mark, as befits an ultra-long-range Mach 5 missile from the transistor era; AIM-4D weighs 135lb, and the fractionally smaller AIM-4C only 119lb. Three AIM-4Ds weigh just a shade over 400lb, not even half as much as one Phoenix.

The other thing that fits in the F-111 internal bay is an M61 Gatling gun with over 2,000 rounds.
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Considering the challenges the F-111 faced I don't think there was much of a chance of it ever getting that capability. But if it were I think you'd want to use the larger variants of the AIM-4. The SARH guided AIM-4F and the IR guided AIM-4G would have better range beneficial for an interceptor. But by the time an F-111 interceptor would be mature enough you'd want it using the AIM-47 anyway.

Honestly, I think an interceptor F-111 might have done the job pretty well for the USAF once the design had matured. But the USAF really wanted the F-12 which had superior performance for that role, and they were sick and tired of McNamara's getting his way all the time.

The way you could fit a 20mm M61A1 in the bay of the F-111 was a cool design but ultimately wasn't worth all of the effort. Strafing runs in such an expensive and large fighter would be a questionable choice. And the USAF would abandon the idea of giving the F-111 better air-to-air capabilities. Was it ever used for anything in service beyond shooting some targets on the ground when training in Nevada? A larger caliber gun would have been better, something like the later GAU-12 but neither the gun nor its 25mm caliber ammunition existed back when the aircraft entered service.
 
Colonial-Marine said:
But by the time an F-111 interceptor would be mature enough you'd want it using the AIM-47 anyway.
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The F-111B skipped over that and went straight to AIM-54. I wasn't advocating fitting AIM-4 to the F-111, merely taking a guess as to how many you could fit in the internal bay. As for the gun in the ground attack versions, it's the ultima ratio regis if I can force an enemy interceptor to overshoot or lay down suppressing fire against something I find myself having to overfly, and I would want it.
 
pathology_doc said:
IIRC it was designed to hold two Phoenix side by side.

According to Wikipedia, Phoenix is 3.9m long, 0.9m in span. Taking AIM-4D as roughly representative of the Falcon breed, we have a 2.02m length, 0.51m span. You might fit three Falcons abreast in the space of two Phoenix, but you won't fit two sets in tandem. The real difference is in the weight. Phoenix is right about the 1000lb mark, as befits an ultra-long-range Mach 5 missile from the transistor era; AIM-4D weighs 135lb, and the fractionally smaller AIM-4C only 119lb. Three AIM-4Ds weigh just a shade over 400lb, not even half as much as one Phoenix.

The other thing that fits in the F-111 internal bay is an M61 Gatling gun with over 2,000 rounds.
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The bay is long enough to hold SRAMs, which are 4.27m long overall. So you can stack 2x AIM4s end to end.
 
Colonial-Marine said:
From what I've read about the Falcon series it sounds like the IR seeker wasn't bad, especially on the later variants including the AIM-4D. When functioning it probably could pick up a heat signature at longer ranges than the Sidewinders of the day could. But the cooling system enabling that caused all sorts of issues with timing. It would certainly be easy enough to intercept bombers with it, but in a dogfight scenario the time it would take to cool down the seeker and the limited time before it ran out of coolant resulted in many missed shots.
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The seeker was good. It just wasn't designed with quick lock-on in mind, since it was assumed that lock would be achieved with the help of automatic fire control system far beyond visual range.
 
Per the article below:

"The GAR-2’s IR seeker encountered problems during testing. In July of 1957, F-102 units conducted Operation FAST DRAW Follow-On at Eglin AFB. While FAST DRAW evaluated the GAR-1D, the follow-on exercise evaluated the GAR-2. Every GAR-2 launched during this exercise failed. During continued testing of the GAR-2, Hughes determined that the IR seeker was very susceptible to external interference from environmental sources such as haze, clouds, and the sun. As the seeker operated in the 2-3 micron range, this was not surprising. Hughes proposed a two-year program to evaluate and solve the issues with the GAR-2. During this period, low-altitude evaluation of the weapon in 1959 illustrated that it was virtually unusable in that environment. The eventual solution was the addition of micron filters to the IR seeker, although this did not completely alleviate the problem." As we know, GAR-2 had a tighter wavelength than later models, but still relatively narrow compared to modern peltier-cooled seekers. So newer models still were limited by the capacity to store liquid coolants. XAIM-4H would have suffered the same limitations.


In this thread, SOC speaks about export Falcons getting modified with proximity fuses.

 

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