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Enthusiast Joined: Apr 10, 2007 Posts: 73 Status: Offline

Sometime back in the weight savings program the SWAT team ruled out JADAM/JSOW advance weapons. Don't think we'll see them on the new F-35B version. These options were replaced with a possible pick GBU-32, about a 1K version of the JDAM.

There was a discussion on this recently, thought I'd bring to to this forum. Shocked

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F16JOAT wrote:

Sometime back in the weight savings program the SWAT team ruled out JADAM/JSOW advance weapons. Don't think we'll see them on the new F-35B version. These options were replaced with a possible pick GBU-32, about a 1K version of the JDAM.

There was a discussion on this recently, thought I'd bring to to this forum. Shocked

The "B" bay was made shorter I believe (~3.7m vs ~4.2 m in the "A" & "C"). This is roughly the length of the F-22 bays. I am not sure if the bay also has a lower ceiling, but there might be given that the 1K JDAM is ~14.1" whereas the 2K JDAM is ~18". The F-22 also has the short 3.7m bays with just enough height to accommodate the GBU-32 1K lbs JDAM.

Just to put the lengths of various weapons in perspective... the GBU-31 (2K lbs JDAM) is ~3.88 m, the GBU-32 (1K lbs JDAM) is ~3.04 m. The JSOW is ~4.16m. The AMRAAM (which we know fits) is ~3.65 m and the Meteor is ~3.66 m. The BRU-61/A with 4 x GBU-39 (aka SDB) is ~3.66m.

Enthusiast Joined: Apr 10, 2007 Posts: 73 Status: Offline

I guess that fan just has to have it's right to mission effectiveness from a hover perspective rather than a A-G support role. The fan sizing also played a big part of the cooling concept to lower the recycled temp of carbon burnt gases from the engine during the hover. Pulls the cooler air from top and mixes underneath the planform. I would be surprised if this is all volumertically sized just to get that air flow based on CFD profiles,aero and thermal as well.

F16JOAT wrote:

I guess that fan just has to have it's right to mission effectiveness from a hover perspective rather than a A-G support role. The fan sizing also played a big part of the cooling concept to lower the recycled temp of carbon burnt gases from the engine during the hover. Pulls the cooler air from top and mixes underneath the planform. I would be surprised if this is all volumertically sized just to get that air flow based on CFD profiles,aero and thermal as well.

The fan has nothing to do with the smaller weapons bay though. The F-35A's intake ducts curve around an imaginary "fan" where the F-35B fan is even though there is no fan. The weapons bay is way aft of the fan.

What may have something to do with the bay resizing is the roll posts that goes through the top of the weapons bay to exit at the undersides of the wings. If these bulked up, it may displace the ceiling of the bay downwards. If you can't accommodate the 18" weapons because of this, there is no longer a reason to make the bays long enough to long enough to accept their length! The alternative is to make expand the belly of the aircraft and lower the floors of the bay. This will increase drag and weight. Maybe that is why they made it smaller.

F-16.net Editor Joined: Sep 23, 2003 Posts: 2848

Remember that whole families of target types can be killed with an SDB, 500lb weapon, and 1000lb weapon. 2000lb weapons aren't used on everything or even needed. Many targets are just as dead if an SDB lands within a sub 4 meter CEP as a 2000lb weapon. So for the B STOVLs, not a big deal.

For the UK they have put up funds to pay for flight tests of the Paveway IV. This excellent bomb kit is not just a laser guided setup but is dual use. It can also act like a JDAM (INS/GPS assisted), And in the case of the Paveway IV you have a wing kit that flips out. So A STOVL showing up with a couple of these internal and a couple of AMRAAMs is not a bad thing.

For the Marines, since USN is investing in Laser/JDAM, in addition to enhanced (dual use) Paveways, Seeing a USMC aircraft with Laser/JDAM will be possible. Navy is also doing HART/JDAM. A wonderful strap-on IIR seaker in the nose. Two HART 500lb/BLU-111 JDAMs inside of a JSF, gives you some good moving target ability on the cheap and some crazy creative precision after takinging a snapshot with the radar.

Having new generation aircraft means that new generation weapons will be created over the long haul. Yes the SDD chart for weapons is all legacy stuff, but over the future expect to see an AMRAAM that can act like ALARM/HARM if it gets funded. And small BAT-like miniture munitions that can loiter a bit and go after moving targets. Of course SDB-II tri sensor from the old JCM project means it will be able to engage precision targets. I do wonder about BRU-61/A smart rack being the way to go for SDBs in JSF. Today, operationally, SDB isn't done without the BRU-61/A rack. SDB is around 275lbs. The rack as someone stated with 4 SDBs is around 1300lbs. BRU-61/A is used because it works but one would think that maybe they will come up with other non-BRU-61/A solutions for hanging SDB in an aircraft. The smaller JSF-B STOVL bay almost demands it?

Yeah it kinds sucks having the bay on STOVL smaller, but it will probably be workable. I want to see a 1000lb forged steel pointy tip little brother to the 2000lb BLU-109. Or even a smaller_than_JSOW glide weapon with a BROACH warhead. The old 2006 SDD chart seems to show limits on the STOVL mission ability on some things. But that is based on current legacy weapons. With a little creativity, I'm not so sure about those limits being real issues in the years after SDD. Be fun to see what the Israelis come up with for their CTOL JSF. Mini SPICE internal? delilah cruise missile?

Remember what it will replace, the Harrier. A step forward for sure. If JSF-B STOVL delivers on the promise and everyone can fess up the money for it, it will be useful for some air arms that are wed to the STOVL idea.

Should find out exactly how the B and A/C bays are different. As DL says, the main internal difference in this zone is due to the roll posts and the plenum around the engine that feeds them. In 2003 (just before the great weight panic) there was some consideration to modding the B bays to hold 2K bombs.
This makes me suspect that it's a diameter constraint.

F-16.net Editor Joined: Sep 23, 2003 Posts: 2848

Would love to be a fly on the wall at the wind tunnel weapons clearnce tests on scale models. Be interesting to see how those bays/doors clear weapons at an angle.

Enthusiast Joined: Apr 10, 2007 Posts: 73 Status: Offline

elp wrote:

Would love to be a fly on the wall at the wind tunnel weapons clearnce tests on scale models. Be interesting to see how those bays/doors clear weapons at an angle.

I would think with the hi-ended trans-sonic speeds that the plane is design to deliver the weapons , should be about the same effect as the F-22 on door or internal bay mounted.

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JADAM/JSOW out of picture