Inside view of bay: comparing B to A&C for various weapo

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delvo

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Unread post09 Dec 2012, 19:53

Several years ago, Kongsberg published a PDF which contained an image of their Naval Strike Missile inside an F-35A bay. NSM won't actually be flown like that; it's just an early illustration of the idea behind the Joint Strike Missile, which will be based on NSM with modifications for F-35. But it still gave us a side view of the internal bay, including a weapon of known size, so it gave us the size of the internal bay itself as well. That means it allows other things of known size to be put on the same scale and copied & pasted in there for comparisons.

The rest of the text here will refer to frames of the animated GIF I'm attaching...

FRAME 1: The original image. To make it more consistent with the images of other weapons I'm using, I resized the whole image to the scale I wanted to work with, rotated it to match other weapon pictures' orientation, and got rid of the missile's red color.

FRAME 2: To get an indication of the difference between an F-35B bay and an A/C bay, I started with SDB-1. We already know a set of four fits in A/C but only three fit in B, and there's room to spare vertically and to the left & right, so the issue must be length.

FRAME 3: The SDB-1s are turned into a silhouette for easy comparison with the SDB-2s overlapping them. We already know that all four SDB-2s fit in F-35B as well as A&C.

FRAME 4: So the obstacle keeping one SDB-1 out of F-35B's bay must be right in that space just barely outside the SDB-2s' front ends and inside the SDB-1s' front ends, or in the one just barely outside the SDB-2s' back ends and inside the SDB1-s' back ends. But which, or is it both?

FRAME 5: We also already know that an AMRAAM fits, and its front tip is well beyond the front of any SDB, so clearly only the back limit we got on SDBs can apply.

FRAME 6: So the actual front limit for F-35B must be at least as far forward as the tip of an AMRAAM. Without another weapon I know of that protrudes farther forward than that and is known not to fit in F-35B, I can't say the limit is exactly there, but it's certainly at least that far forward. (Actually I don't think B is any more restrictive in front than A/C at all, but I'm leaving the bare-minimum-guaranteed line in there so we can all see it anyway.)

FRAME 7: Now that we have the front and back limits for weapons that can be guaranteed to fit in F-35B, we can see whether other things would fit B. To start with, I had never heard whether the planned adapter to fit a pair of AMRAAMs would work in B or just A&C, because it would require some front-to-back offset to keep the fins clear of each other. But now I know, because the offset pair fits inside even the tightest possible space restriction for B.

FRAME 8: So does a 500-pound Paveway bomb.

FRAME 9: So does a plain original-flavor 500-pound bomb, which I'm sure nobody doubted...

FRAME 10: ...but so would a pair of them. (I just made that adapter up; I've heard no word that anybody is actually building such a thing.)

FRAME 11: 1000-pound JDAM, no surprises there

FRAME 12: 1000-pound Paveway's front tip reaches farther forward than anything else I know of that even fits A/C. Is there any word on whether it fits B? It's in front of the line based on an AMRAAM's tip, but I don't know of anything else F-35B would have cluttering up the front of that space that A&C don't have. If this bomb fits, we can ignore the line based on the tip of the AMRAAM.

FRAME 13: JSOW, no surprises there... I can imagine a change that I think would allow it to fit, but I don't believe anybody who matters is going to invest in doing it just for one version of F-35, when it already can fit the other two.

FRAME 14: Back to NSM, this time with the lines included in front & back. It already fits inside the back line. It does extend about an inch in front of the front line, but that's the one that might not represent a real-world restriction, and even if it does, it's so close that making the JSM fit wouldn't be difficult when they're already modifying the NSM to make JSM anyway.
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F-35 bay.gif
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aceshigh

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Unread post09 Dec 2012, 20:52

Nice work!
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marksengineer

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Unread post09 Dec 2012, 22:30

Nice work but from my experience with line drawings found in publications and on the net there is sometimes little coorelation between them and the airframe components. If you import them into engineering software you may find that corners that should be perpendicular aren't and lines that should be parallel are not either. It gets you close they aren't accurate
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megasun

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Unread post10 Dec 2012, 07:54

Wow, if JSOW doesn't fit Bee, that's a problem for UK carrier, and IT and ... etc. NSM will be the only choice of cruise missiles.

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