F-22's weapon bay capacity

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linkomart

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Unread post13 May 2014, 10:11

delvo wrote:
linkomart wrote:The meteor span is a lot more than the AMRAAM, and I'm pretty sure you won't find any oficcial numbers. It's also not symmetrical top/bottom since the bottom finns are located on the sidepods behind the air-intakes.
Images like this one and this one show the fins making a square with height & width 2.3 times the central body's diameter, which means 16.1".


There were a lot of initial versions, from the begining there were even plans to have eight fins just like the AMRAAM. My guess is that it is an early image. As far as I can tell METEOR have four equal sized fins, but since the lower fins are located on the sidepods the span is slightly larger.
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disconnectedradical

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Unread post13 May 2014, 12:15

Perhaps a better question is what's the largest box section that can be fitted in the main bay. I've heard that it's about 0.35 meters, in which case the AIM-120A/B can't even fit into the bay at all due to the 25 inch fin span (21 inch is for the middle fins).
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Unread post23 May 2014, 23:57

Do clipped fins affect manoeuvrability?
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hephaestusaetnaean

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Unread post23 Mar 2015, 22:26

F-22 weapons bay dimensions

Each bay is at least 13.4 inches tall x 33.9 inches wide x 156 inches long. That's the geometrically smallest box in which you can fit AIM-120D's 3-abreast and staggered. Add 4 inches of width and 3 inches of length for each inch of separation between missile/missile and missile/wall.

Obviously, I don't need to know the true dimensions, but since Raytheon clipped the -120C's wings just enough to fit inside the raptor, we can assume for our arguments that the bay can't fit anything larger than the -120D.

AIM-120D in the F-22

Each -120D measures 12 ft long, 7 inches wide, 19 inch wingspan, with 12 inch long fins. Each fits in a 13.4 x 13.4 x 156 inch box. The center missile is staggered forward 12 inches to make room so the fins don't overlap, allowing the triplet to nestle closer together, occupying only 33.9 inches of width instead of the 40.2" they would otherwise. Again, the box for all 3 is 13.4 x 33.9 x156 inches (H/W/L)

For comparison, three 120C's would occupy 36.7 inches of width (and 14.8 inches of height) given their 21 inch wingspan. Presumably this makes them too large to fit.

MBDA Meteor in the F-22

Each meteor measures 12 ft long, 7 inches wide, 25 inch wingspan, with 12 inch long fins. Each fits in a 17.7 x 17.7 x 156 inch box. Fitted 3-abreast and staggered like the 120's, they measure 17.7 x 46.1 x 156 inches (H/W/L). (Again, add 4 inches of width and 3 inches of length for each inch of margin.) That's much too wide.

The issue are the intakes, which protrude down and out, making the body effectively 10.75 inches wide (much wider than the 7 inch diameter casing of the main body), so the missiles can't sit as close to each other.

Fitted with just 2 meteors per bay, they occupy only 28.4 inches of width (less than -120D), but are still too tall at 17.7 inches, which again is taller than even the -120C.

In order to fit 3 Meteors per bay (abreast and staggered), the fins would have to be clipped to half their span (4.7 inches vs 9 inches each), yielding a wingspan of just 16.4 inches (down from 25 inches). (Box = 11.6 x 33.9 x 156 inches H/W/L.) Unfortunately, that means the lower fins barely protrude out from behind the intakes. And the fins can't be lengthened (either much or at all) because that'll increase the length occupied.

That might be too small, and the control issues might be unacceptable. To offset the smaller, less effective fins, they could add another set of fins, or add strakes, or add jet vanes for thrust vectoring. All of these have their own issues.

Or instead of clipping the fins, MBDA could slim down the intakes or even reorient/reposition them to narrow the body width. This will obviously reduce thrust and turning performance ... or require a major rework of the combustor (read: not going to happen).

It's not clear which option MBDA will choose to fit the Meteor into the F-22 and F-35. For sure the fins will get clipped. Maybe the intakes will shrink, reducing speed and the NEZ a tad. Maybe they'll make folding fins strong enough to endure external carriage---very straightforward option with the least impact on the rest of the missile, but I've never heard anyone seriously consider this, so maybe it's impractical. Although Have Dash II tried it. Clipped wings with TVC also seem like a workable option.

AIM-152 AAAM GD/Westinghouse in the F-22

Each -152 measures 11.8 ft long, 7 inches wide (wings folded). Encapsulated, they fit in a canister 11.25 x 8.75 x 144 inches (H/W/L).

Fitted abreast 3 per bay, they occupy a box 11.25 x 26.3 x 144 inches H/W/L. Far less than the 33.9 inch width "limit." You could almost fit four per bay (35.0 inches).

In reality, you probably could fit four per bay, since the rounds are safely encapsulated (assuming the tube separated well and could launch the missile after being dropped, which they probably weren't designed to do). You could definitely fit four per bay if you strengthened it for internal carriage and launched without a tube, since the rounds are only 7 inches wide.

---

Approx dimensions of the meteor and aim-152 are taken from pics similar to the ones posted here.
This questions crops up often enough, so here we go.
Last edited by hephaestusaetnaean on 24 Mar 2015, 01:47, edited 2 times in total.
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hephaestusaetnaean

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Unread post23 Mar 2015, 22:33

Btw, is T3 still alive? Did anything come out of it?

According to this FY15 Budget estimate from March 2014 http://www.darpa.mil/workarea/downloada ... 2147487546,

The Triple Target Terminator (T3) program developed a high speed, long-range missile to engage air, cruise missile, and air defense targets. T3 would be carried internally on stealth aircraft or externally on fighters, bombers, and UAVs. The enabling technologies are: air breathing propulsion, advanced networking and data links, and flexible guidance and control. T3 would allow any aircraft to rapidly switch between air-to-air and air-to-surface capabilities. T3's speed, maneuverability, and network-centric capabilities would significantly improve U.S. aircraft survivability and increase the number and variety of targets that could be destroyed on each sortie. The program is jointly funded with, and will transition to the Air Force.
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Unread post24 Mar 2015, 01:24

Instead of clipping, why not go with folding fins (-120 and Metior)?


btw, the GD AAAM was always my favorite version too (6-8 per bay, not 4 [double stacked]).
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Unread post24 Mar 2015, 07:41

Yeah, folding fins seems like the obvious solution. But apparently they don't stand up well to the rigors and wear n tear of external carriage, whereas internal bays are much more benign environments. (It doesn't seem that hard to make a reliable hinge robust enough to survive long hours hanging from a pylon, or to wrap the fins in a jettisonable protective shroud, but what do I know?) (There might also be an issue accommodating folding fins into semi-recessed mounts.)

Have Dash II did use folding fins and could be carried both internally and externally. Never entered service though.

Also, the USAF didn't want to operate two variants of AMRAAM, one for external carriage, one for internal bays (solely the F-22 at the time).

This may not matter to MBDA; they're aiming for the internal AAM market (basically just the F-35 at the moment), but since their pre-existing Meteor can't fit in internal bays, they'll have to make a new variant anyway, they may as well use folding fins.

But it does matter to anyone buying it for their F-35's, who would prefer the new variant to work on their current 4th gen (externally) without having to buy two versions.

I don't really see us buying either variant of the Meteor though. Whichever BVRAAM we buy we'll use for the next 40+ years... with all the upgrading and O&S that entails. We will likely make our own... at some point. So it doesn't make sense to buy the Meteor and build up a support structure only to use it just for the 15 year interim until we field our own BVRAAM. It would make more sense to hack together an ERAAM or "-120E." ...And I certainly don't see us using a European AAM for 40 years, regardless of how good it is.

Besides, in order "to make [the Meteor] interchangeable with the AMRAAM on the Eurofighter, the semi recession dictated [fixed dimensions that matched the AMRAAM, ie 12ft x 7inches]." It also dictated, I think, using two inlets instead of four, which reduced performance at negative g's and sideslip, thus dictating bank-to-turn (since it couldn't take full advantage of TVC anyway).

We can do better. We're not locked into 12ft by 7inch semi-recessed (many of ours will retire before we field a new BVRAAM anyway), which opens up a lot of options:
  • We can widen the casing diameter to 8 inches: more fuel, wider aperture for sensors (easier to integrate dual band radars, or multi-mode seekers, eg radar/EO/IIR).
  • A large diameter separable booster with TVC (instead of the smaller, less efficient, integrated nozzle-less booster in Meteor) that separates post-boost to reduce weight and drag. Being modular, we can tailor the motor to each launch platform, eg 10" for the F-22, 14" for the F-35, a longer 14" for a B-1R standoff missile bus (arbitrary diameters).
  • Four inlets. Without having to accommodate semi-recessed mounting, we can fit four (smaller) inlets symmetrically around the body. Meteor's sideslip and negative AOA issues disappear.
  • TVC. Easier in a larger diameter body and without sideslip/AOA issues.
  • Stealthy trapezoidal body. Again, don't have to fit semi-recessed.
I'm not saying we should do all these things, or even that they're good ideas, but the options are available to us.

--

What impressed me most about the GD AAAM was the sheer range they claimed in a frame smaller than the AMRAAM. Not to mention all the other innovative features: multipulse motors, separable booster, multimode seeker (dual band radar AND 2 color IR), tube launch... simultaneously ahead of its time and born too late.
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Unread post24 Mar 2015, 10:54

How many ESSM would fit?
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Unread post24 Mar 2015, 12:57

Maybe they can find a way to squeeze this in.

http://alert5.com/2015/02/24/amraam-er- ... e-section/
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Unread post26 Mar 2015, 03:30

RIM-162 ESSM's in the F-22

sferrin wrote:How many ESSM would fit?


3 ESSM's fit perfectly (without any modifications to neither the missile nor bay, except attachments). 4 ESSM's would not fit unless the rounds were spaced just 7.62mm apart.

Each ESSM is 12 ft long, 10 in wide, with a ~25.2" wingspan (~14.7" folded wingspan), and ~8.2" long fins. Each fits into a box 10.8" x 10.8" x 144" (H/W/L). Fitted three abreast and staggered, the box is 10.8" x 32.2" x 152.2" (H/W/L). That's slightly less than the -120D (mostly just squatter).

It's noticeably larger than you'd expect because the fins don't fold quite flat (see below) and and the strakes (which span a touch more than the folded fins) are too long to be staggered, making the body effectively 0.6" wider.

Image

One caveat. You need to delete a rear section of strake so the folded fins can be staggered. But this only saves 0.2". If the strakes and fins (folded) were clipped from 2.3" down to 1.5" (each side), they wouldn't protrude outside the 10" body's "box", saving 2.4"... enough room to enlarge the casing from 10" to 11". Basically, the ESSM is narrow enough that it doesn't need to be staggered at all.

So a much better idea, I think, is to not stagger the missiles but use the extra length to stretch the rocket motor by 12+ inches. You only increase the fuel by ~12% instead of 21% (vs 11" casing), but this is a lot easier and doesn't sacrifice agility. (Box = 10.8" x 32.4" x 156" H/W/L, still less than -120D)

A 10" sensor aperture does make it easier to fit a multi-modal ARH/EO/IIR seeker...

And the performance should... impressive. If not Meteor-like, definitely "-120ER" worthy.

---

BTW, judging from a pic of the F-22 bay, it looks like the center missile is staggered forward at least 13.15 inches (implying >1.15" of fore/aft separation between fins), and laterally the AMRAAMS are very tightly packed with very little separation between adjacent casings/fins. I doubt anything larger than -120D's will fit.
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Unread post29 Mar 2015, 03:53

I'm not sure if we can say that the F-22 can't carry the AIM-120A/B. I've read that it can carry four of those missiles in lieu of the six clipped-fin AIM-120C/D.

I believe the A/B models have 25 inch span compared to the 17.6 inch span of the C/D. Incidentally the A/B takes up approximately 17.6 x 17.6 square inch cross section. Here are some pictures of the F-22's internal bays. Also, the GBU-32 has a 19.6 inch span, but I think the BRU rack has lower profile than the LAU-142.

Image
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Unread post29 Mar 2015, 22:31

You're probably right. For sake of argument, it can be useful to assume nothing larger than the -120C/D can fit [three-abreast per bay]. Otherwise, people like to play with the margins and try to cram all sorts of things that don't belong in there.
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Unread post30 Mar 2015, 05:17

Also, what's the span of the C/D? I'm getting conflicting reports, because some say it's 19 in, and some say 17.6 in.
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Unread post03 Apr 2015, 21:58

~17 inches at 1:03: .

Although the navy fact sheet says 19 inches. Maybe they trimmed the D even more than the C?
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Unread post09 Apr 2015, 11:58

Definitely looks like 17.6 inches here.

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