Alternative AAM history: AIM-4H enters service.

Just a theoretical speculation. Let's imagine that McNamarra relented a bit and allowed Air Force to redesign their version of Phantom to better suit their needs. So they decided to make a Phantom with the same highly capable MA-31 FCS as Delta Dart, and with internal storage for AIM-4 Falcon missiles.

Would it be possible to fit the internal weapon bay(s) on F-4 Phantom, to store & launch, say, four AIM-4 missiles (or a pair of AIM-26 Super Falcon or a pair of AIR-2 Genie)?
 
NMaude said:
I doubt it, not without a massive redesign of the F-4's airframe which would no doubt mean it's an F-4 in name only.
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True, the plane internal arrangement is rather... tight, and engines are low-placed.

Still I think a belly weapon bay, shaped like proposed conformal fuel tanks for Super Phantom, would be possible:

my-conformal-tank-contribution-the-proposed-options-for-the-v0-m79kyohzhkdd1.jpg

After all, four Falcons in two pairs (one after another) require just about 5 meters of length and 0,5 meters of width/heigth to store.
 
Dilandu said:
True, the plane internal arrangement is rather... tight, and engines are low-placed.

Still I think a belly weapon bay, shaped like proposed conformal fuel tanks for Super Phantom, would be possible:

View attachment 768271

After all, four Falcons in two pairs (one after another) require just about 5 meters of length and 0,5 meters of width/heigth to store.
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It'd have to be scabbed on like that, there's no space in the belly of a Phantom for a weapons bay.
 
My guess is the USAF would be happy to settle for externally carried Falcons and the associated FCS.
 
Yellow Palace said:
My guess is the USAF would be happy to settle for externally carried Falcons and the associated FCS.
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Yes, the USAF would settle for the SAGE FCS.

But if you showed them that the belly tray would make the plane faster than with having everything out in the breeze, I bet they'd buy a "belly tray bay plus FCS upgrade" over just an FCS upgrade.
 
Okay, so my idea that seemingly might to work: one long, semi-recessed conformal weapon bay installed between engines roughly at the place of centerline fuel tank.

Two sections, one after another. Each designed to accomodate either two AIM-4 missiles (one after another) or one AIM-26 missile on trapeze launchers.

According to the charts I was able to find, the 600-gallon CL tank & four AIM-7 arrangemend allowed F-4E to reach Mach 2+ velocity (the tank could withstand only about 1.65 Mach, though). So as long as summary drag coefficient from ventral weapon bay would NOT exceed the summary drag of abovementioned payload, the F-4E would be fine.
 
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Figure out a fighter version of the A-5 without a ridiculous 3rd engine.
 
Scott Kenny said:
That would require making a whole new forging of the frames in the tail supporting the engines and tail surfaces.

The A-5 had no space for larger diameter engines without that.
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The J79s should've been adequate for an interceptor version of the A-5 and the space that had been occupied by its' linear bom-bay could instead have been used for a weapons bay holding several Falcons (Maybe the AIM-47) or Sparrows and the rest of the space extra internal fuel tanks.​
 
Would be fun to use the Vigilante linear bomb bay to drop air-to-air missiles instead of nuke and fuel tanks. They would need clipped fins, however. Well, maybe not !
https://www.secretprojects.co.uk/threads/a-5-vigilante-conventional-weapon-load.10925/#post-103032

Diameter : 0.76 m that is, 30 inch.
https://en.wikipedia.org/wiki/AIM-4_Falcon#Specifications_(GAR-1D/_-2B_/_AIM-4C/D)
https://en.wikipedia.org/wiki/AIM-9_Sidewinder#Design

Now that's funny: AIM-4 and AIM-9 would fit ! How about that ??
 
Digging further : AIM-7B was 2ft, 8-inch span (81 cm) when the linear bomb bay was 2ft, 6-inch (76 cm). So with a little fins clipping, AIM-7 would fit, too ! Unbelievable. Down the rabbit hole... !

I mostly agree with you @Dilandu that the AAMs would need adaptation to very different launch conditions. Instead of dropping like dumb bombs, they would pop rearwards, out of the A-5 tail; passing between two J79s blowtorches. Probably would do no good to the damn unreliable things.

The only silver lining would be, before launch they would be comfortably nested deep inside the A-5 guts, so much more protected than a Phantom classic "outside" carriage.

Considering the missiles length vs linear bomb bay length (9 m vs 3 m average), a maximum of three AIM-7 or AIM-9 could be carried: front, middle, rear. You could get a mix, obviously : 2 Sparrows and 1 Sidewinder, or reverse.

Falcon is much shorter : 2 m, so 4 could be carried internally.
 
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Archibald said:
I mostly agree with you @Dilandu that the AAMs would need adaptation to very different launch conditions. Instead of dropping like dumb bombs, they would pop rearwards, out of the A-5 tail; passing between two J79s blowtorches. Probably would do no good to the damn unreliable things
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My main concern is that AIM-4 seeker would not be able to maintain pre-set lock on target.
 
Archibald said:
Digging further : AIM-7B was 2ft, 8-inch span (81 cm) when the linear bomb bay was 2ft, 6-inch (76 cm). So with a little fins clipping, AIM-7 would fit, too ! Unbelievable. Down the rabbit hole... !
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Just clip the tips of the tail-fins and have folding wings just like in the RIM-7 Sea Sparrow.

Now why would NA have an interceptor version of the A-5 launch its' AAMs by ejecting them tail first out of the rear just like with the A-5's linear bomb-bay and its' nuclear payload? An interceptor version of the A-5 carrying AAMs in its' weapons bay would almost certainly launch them ventrally through open IWB doors.​

However this is what the NA A-5 interceptor looked like:

North_American_NR-349_%2834410707756%29.png
 
Archibald said:
The only silver lining would be, before launch they would be comfortably nested deep inside the A-5 guts, so much more protected than a Phantom classic "outside" carriage.
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The only way I could imagine the Vigilante internal carriage to work, is to have some kind of telescopic rail, portruging from weapon bay to slide missile along it outside. Still, there would be major problems: first of all, the missile couls hit the bomber itself, accelerating from behind. Second, the missiles with IR seekers would likely be confused by bomber engine heat, so they could not be used.
 
IR seekers would likely be confused by bomber engine heat
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Crap, you're right, that's the J79 blowtorches I mentionned. Oh well, at least it was a funny speculating exercise.
 
Archibald said:
Crap, you're right, that's the J79 blowtorches I mentionned. Oh well, at least it was a funny speculating exercise.
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The only viable solution is to somehow fit a ventral hatch leading to Vigilante's bomb bay from forward, so missiles could be lowered on trapeze & launched from below the plane.
 
Dilandu said:
The only viable solution is to somehow fit a ventral hatch leading to Vigilante's bomb bay from forward, so missiles could be lowered on trapeze & launched from below the plane.
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i think it's perfectly reasonable to have a missile bay like a six
 
An interceptor version of the A-5 would likely have had an IWB with ventral bay doors something similar to what the Su-57 has.

Moving along, in this scenario where the AIM-4H does enter production I have no doubt it would quickly replace ALL of the remaining AIM-4G IR Falcons carried by the F-106, now what about on ANG F-4C and F-4D fighters? How much competition would it have been with the AIM-9L?​
 
Two modernized J79s were probably more than suitable. North American had problems with producing affordable fighters even when they had the market on F-86, which was probably why its a never explored subject.
 
NMaude said:
An interceptor version of the A-5 would likely have had an IWB with ventral bay doors something similar to what the Su-57 has.

Moving along, in this scenario where the AIM-4H does enter production I have no doubt it would quickly replace ALL of the remaining AIM-4G IR Falcons carried by the F-106, now what about on ANG F-4C and F-4D fighters? How much competition would it have been with the AIM-9L?​
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None, since the -9L doesn't come along until significantly later.

Probably all the -9Ls get reserved for dogfighting in Europe. The ANG Phantoms don't need them, because unless they're based down in Florida and expect to be dealing with fighters out of Cuba, they're extraordinarily unlikely to be dogfighting at all.

Even then, ROE restrictions on an enemy incoming to the US are going to be somewhere between loose and disregarded. Anything with a Sparrow is likely to take a BVR shot on anything incoming, and say sorry later for any airliners caught up in a shooting war that might already have gone nuclear anyway.

In the wake of the -4H entering production both for combat in Vietnam and to have as fresh stock for the ADC and ANG fighters all the way out to the Six's retirement in '88, I wouldn't consider it all that unlikely for ongoing improvements to result in an all-aspect AIM-4J.
 
NMaude said:
Moving along, in this scenario where the AIM-4H does enter production I have no doubt it would quickly replace ALL of the remaining AIM-4G IR Falcons carried by the F-106, now what about on ANG F-4C and F-4D fighters?
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Is Colonel Olds still pissed off at the AIM-4 for costing him 3 war Ace status? If not, then it might be possible that the USAF doesn't adopt AIM9s till the Teen series, and so has F-4Ds with Falcons instead of ripping out the Falcon wiring for Navy Sidewinder wiring. F-4Cs came with Sidewinders, since they were Navy stock and only refitted with USAF radios. Only a few of them were refitted with Sidewinders later in life, just some of the RF-4Cs.

This does suggest that the USAF would still fight to not take AIM-95 AGILEs over AIM-9Ls, as even Lima Sidewinders would allow for cheap fighters to take out their expensive F-15s in double kills due to needing to continue to close in with the SARH Sparrows.

However, with the greatly reduced USAF buy of AIM9s (no Phantoms with AIM9s once the -Cs were retired), the Navy might have enough institutional power to get AIM95s for the carriers, along with Phoenix and Sparrows then AMRAAMs.


pathology_doc said:
In the wake of the -4H entering production both for combat in Vietnam and to have as fresh stock for the ADC and ANG fighters all the way out to the Six's retirement in '88, I wouldn't consider it all that unlikely for ongoing improvements to result in an all-aspect AIM-4J.
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With the Lima Sidewinder coming out in 1982ish, you're probably right. At least in testing. I'm not sure how much demand there would really be for an all aspect Falcon in the ADC/ANG mission.

Maybe if the F-4s kept Falcons?
 
Scott Kenny said:
Is Colonel Olds still pissed off at the AIM-4 for costing him 3 war Ace status? If not, then it might be possible that the USAF doesn't adopt AIM9s till the Teen series, and so has F-4Ds with Falcons
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What kind of FCS they would use? AIM-4 on basic F-4D FCS would be of little use.
 
Dilandu said:
What kind of FCS they would use? AIM-4 on basic F-4D FCS would be of little use.
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If they're working at ADC I'd expect they'd use the same FCS as F-106s (or a developed version of it).

This is one of the places where the USAF getting a Navy plane kinda screwed them over. It didn't have the USAF FCS that the USAF missiles required to be effective, and was never refitted with said FCS.
 
Dilandu said:
That would be good. What about my concept of installing ventral weapon bay on F-4D, so they could carry AIM-4 missiles (and/or AIM-26) internally?
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Too much drag. You're basically installing an under-fuselage pannier because the space immediately above the belly is taken up by other things. Unlike prop planes, there's very little empty space inside a modern jet. By the time you rearrange that space to fit a truly internal weapon bay, you might as well make a new airplane because it's going to make the F-4K look like a line-squadron hangar modification by comparison.
 
Dilandu said:
That would be good. What about my concept of installing ventral weapon bay on F-4D, so they could carry AIM-4 missiles (and/or AIM-26) internally?
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Combined response:
pathology_doc said:
Too much drag. You're basically installing an under-fuselage pannier because the space immediately above the belly is taken up by other things. Unlike prop planes, there's very little empty space inside a modern jet. By the time you rearrange that space to fit a truly internal weapon bay, you might as well make a new airplane because it's going to make the F-4K look like a line-squadron hangar modification by comparison.
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IIRC MDC proposed a belly conformal fuel tank that would do a decent job in 1981.


So it would work pretty well. Might not end up with full enclosures, but it would end up pretty well.
 
pathology_doc said:
Too much drag. You're basically installing an under-fuselage pannier because the space immediately above the belly is taken up by other things. Unlike prop planes, there's very little empty space inside a modern jet. By the time you rearrange that space to fit a truly internal weapon bay, you might as well make a new airplane because it's going to make the F-4K look like a line-squadron hangar modification by comparison.
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Well, I checked the graphs -

1767882888458.png

- and the drag from 600-gallon CL tank & four AIM-7 did not prevent F-4E from reaching Mach 2+. Arguably the belly weapon bay in semi-recessed blister would give less drag.
 

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