Possible configuration of the Northrop Grumman F/A-XX

[Seragina]

Yeah, but the more interesting thing for me is it's at least about the same length as the F-105 Thunderchief's.
according to wikipedia

The bomb bay measured 15 feet 10 inches (4.83 m) by 32 in (0.81 m) by 32 in (0.81 m)

A size I've eyed long before all this; mainly wondering about the F22's bay size limitation.

 

[Scott Kenny]

mainly wondering about the F22's bay size limitation.

What about it? The issue is that the F-22 got infected with "not a pound for air to ground" so the weapons bay is not deep enough for 2000lb weapons. It is coincidentally deep enough for 1000lb weapons because they're as big around as the clipped AMRAAM fins are.

For sake of argument, let's give a hypothetical F/A-22 bulged weapons bays to hold a pair of 2000lb weapons. There's only enough space for 2x AMRAAMs in the main bay and then the two Sidewinders in the side bays. So an F-22 carrying 2000lb bombs is basically only armed as well as an F-35.

 

[Seragina]

I don't think 1000 lb allocation was a coincidence because traditionally, cold war fighters had always been made with a nuke carry cababillity in mind should there be war. It's just politically no longer correct or official with all the nuke reduction treaties in effect. But the military would be incomepent not to account for the worse case regardless.

Anyhow, my quick and dirty sizing attempt and comparision with the newly revealed small Air-Launched Rapid Response Missile (ALRRM).
It looks reasonable but length feels a bit short.

 

[Scott Kenny]

I don't think 1000 lb allocation was a coincidence because traditionally, cold war fighters had always been made with a nuke carry cababillity in mind should there be war. It's just politically no longer correct or official with all the nuke reduction treaties in effect. But the military would be incomepent not to account for the worse case regardless.

Except that the B61 is the same diameter as a 2000lb weapon, despite weighing less than 1000lbs in most models.

Anyhow, my quick and dirty sizing attempt and comparision with the newly revealed small Air-Launched Rapid Response Missile (ALRRM).
It looks reasonable but length feels a bit short.

I'd stretch the warhead and rocket motor to ~14ft.

 

[Seragina]

I'd stretch the warhead and rocket motor to ~14ft.

With a finess ratio of 5.5 the vehicle is a bit short of ideal but I don't think it's powered beyond maneuvering burst if ever so it won't matter.
Including the 2nd stage the finess ratio becomes 8 which would means it's for terminal burst to perhapst pull up for a more precise hit as well as avoid defenses. That's why I don't think lengthening them is necessary. In any case, the error margin to the real thing is only 0.77" or less than 0.1 for finess ratio. There's simply no room here for speculation.

As for the motor, it could be beneficial to be longer. With a finess ratio of 12 it's clearly meant to be a fast and "short" range. The main question I have is the ratio between the 1st and 2nd pulse's fuel fraction allocation. This determines sustain time.
Assuming flight time to be around 240 s and sustain ~70 s then each foot increase could add perhaps 16s for like 13 nm more.

 

[Scott Kenny]

What I mean is that even the F-22 has a 156" long main bay, IIRC, so it'd be viable to stretch that missile past "AMRAAM length"

 

[Seragina]

IC Well, to give a different perspective. When adding the rack placement to the picture and aligning such that both's CG point match the "full size" happens to fit best. On the other hand placing it into the F22's bay it appears there's not much room for negotiation.
Some changes are still possible but it won't be significant.

Let's move onto what's still missing from inventory.
Let's recap on the original plans:

The USAF always had wanted stand-off weapons for the next generation of weapons. A modular design to use GP bomb warheads with jet/rocket motors in a similar way as JDAM.
Due to range requirement for slow options we have now JDAM-LR that limited to 500 lb MK82, Barracuda-250 for 150 lb and other similar cheap options.
For fast strike we now have various ALRRM sizes (AGM-181, HyFly and this ALRRM)
So what's left is the penetrator version.
Considering F22/F35 bay length and similar body design as the GBU57's L/D=7.75 we get 20" for diameter. Needless to say this would require a motor that far exceeds bay size. But if I go for a finess ratio of 16 that is more ideal the diemater happens to become 9.75" and would fit the ALRRM's design.
That said I don't think this size is what the USAF want's and it may not give the depth penetration desired.
My guess would be a 13" penetrator combined with a 21" motor. The deciding factor, however, is the stand-off range of presumely 300-350 km.
Anybody got something to bid here?

 

[Seragina]

Continuing with my musing.

Apparently, AFRL had 2000 lb warhead with 3000 lb motor in mind:

High Velocity Penetrating Weapon Addresses “Hard Target” Challenges | Defense Media Network

The United States Air Force is addressing the challenges of a new generation of “hard target” engagements through a recent broad agency announcement releas

www.defensemedianetwork.com

But this obviously would have become AGM183 size and wouldn't fit into a IWB.

Assuming "old" rocket motor was originally used for sizing, I'm applying the new heavy loaded grain that gives 1.5x improvement.
Hence, instead of the old 3000 lb motor the new motor only needs to be 2000 lb. The new mass ratio become 1:1.

I assume the F22 will only be used for escort and support behind the F47 I remove it from consideration as a carrier platform.
This leaves the F35's bay as the minimum size. Considering a conventional cylindric form I get about 2050 lb as the pure missile size limit. I think a hybrid rectangular form would be best but that's a bit too troublesome for a quick and dirty attempt.

That gives me ~1285 lb for warhead and motor respectively. Using the GBU72 as a base for scaling I get 0.662361x, hence, a diameter of 11.92" and a length of 74.62" for the penetrator.
That leaves 81" for the motor with a 18" diameter which gives me ~1045 lb.
The remaining 240 lb will go over the warhead for at least 33.2" without tapering.

It's almost only about 20% of the GBU72's destructive content which might not be sufficient for destroying much of a bunker.
Edit: Based on rule of thumb and based on the speed requirement given I assume minimum penetration depth to be ~130 ft=40m.
For 200 ft hypersonic velocity is necessary..

 

[Scott Kenny]

This leaves the F35's bay as the minimum size. Considering a conventional cylindric form I get about 2050 lb as the pure missile size limit. I think a hybrid rectangular form would be best but that's a bit too troublesome for a quick and dirty attempt.

I've gotten lazy and used the dimensions of the JSM. 19x20"

 

[Seragina]

On a side note AFRL has been including Mk83/1000 lb warheads as part of desired future upgrades in the past.
But range requirement and resulting irl solutions clearly has put these back compared to the preferance or limitations to ~150 lb, 500 lb and 2000 lb warheads. I assume this is mainly due to the preference for IWB and or underwing carriage (for even longer ranges)

Since cluster ammunition have been used again I suppose we'll see more of them getting adopted likewise. And very likely with the same form factor I've used for the penetrator because of volume requirement.

Anyhow, since F/A-XX selection is coming soonish I suppose I'll have to post right beforehand.