F-22, F-35 & similar a/c weapon bay question

[Todjaeger]

A question occurred to me when I was thinking about current and upcoming 5th generation aircraft.

Given the apparent need for VLO capabilities and the resulting shaping, as well as the difference in RCS and air resistance between stores mounted on a hardpoint vs. carried in an internal bay, I began thinking...

Are either the F-22 or any of the current F-35 variants (A/B/C) capable of carrying a droptank in the internal weapons bay? If not, how difficult would it be to modify a design so that it is plumbed for an internally carried droptank?

From my perspective, some long-range missions could be enhanced by carrying additional fuel internally, with longer range due to greater total fuel carried and overall improved fuel efficiency vs. external droptanks. Also a LO/VLO aircraft would not be increasing the RCS while in flight. By extension, this could reduce the number and amount of AAR missions required, increasing the effectiveness of the AAR fleets different nations have, or in the case of the US, reduce the stresses put upon a very old AAR fleet.

Would design of droptanks for internal weapons bays being a viable idea, or have others already considered it and rejected it as too difficult, too dangerous, too expensive or not effective?

-Cheers

[Ozzy Blizzard]

A question occurred to me when I was thinking about current and upcoming 5th generation aircraft.

Given the apparent need for VLO capabilities and the resulting shaping, as well as the difference in RCS and air resistance between stores mounted on a hardpoint vs. carried in an internal bay, I began thinking...

Are either the F-22 or any of the current F-35 variants (A/B/C) capable of carrying a droptank in the internal weapons bay? If not, how difficult would it be to modify a design so that it is plumbed for an internally carried droptank?

From my perspective, some long-range missions could be enhanced by carrying additional fuel internally, with longer range due to greater total fuel carried and overall improved fuel efficiency vs. external droptanks. Also a LO/VLO aircraft would not be increasing the RCS while in flight. By extension, this could reduce the number and amount of AAR missions required, increasing the effectiveness of the AAR fleets different nations have, or in the case of the US, reduce the stresses put upon a very old AAR fleet.

Would design of droptanks for internal weapons bays being a viable idea, or have others already considered it and rejected it as too difficult, too dangerous, too expensive or not effective?

-Cheers

They would need the plumbing to allow that to happen, and AFAIK neither of them are plumbed for internal fuel carriage. For any combat ops your going to displace the weaponry putting it on the external hard points.

Making a tank fit in the internal bay would pose some interesting engineering challenges in terms of shape and weight distribution, although certainly not impossible.

In any case I'm not sure how useful internal drop tanks would be apart from increasing your maximum ferry range, and in many cases is dictated by AAR anyway.

[rjmaz1]

If the F-22/F-35 were to be used as an unarmed recon aircraft then they could potentially replace the weapons with a fuel tank for longer range. As far as I know there is no plumbing for such tanks.

However i cannot think of any missions based on the current design roles that would see anyone willing to sacrifice weapons for a small 20% range increase.

Both aircraft have been designed with very large internal fuel capacities from the start. 3rd and 4th generation aircraft always carrying external fuel tanks has been a valuable experience.

[Salty Dog]

3rd and 4th generation aircraft always carrying external fuel tanks has been a valuable experience.

AFAIK the Su-27/30/33 family operates without external fuel stores. They have so much internal fuel volume, it's not been a necessity. They might not even have the plumbing for external fuel stores, I don't know for sure.

[Ozzy Blizzard]

AFAIK the Su-27/30/33 family operates without external fuel stores. They have so much internal fuel volume, it's not been a necessity. They might not even have the plumbing for external fuel stores, I don't know for sure.

AFAIK They are plumbed for external carriage, I've seen an Su-30 with AAR tanks in between the nacelles so it makes sense that they would be plumbed for those tanks.

[weasel1962]

Deleted

[Salty Dog]

If stealth is required, just fly the plane to a base within the radius of ops that doesn't need drop tanks. If there aren't any bases which doesn't have its radius of ops (which is unlikely in today's context), then create one (which is irrelevant in the context of the VTOL model as a base can be readily created almost anywhere for operations).


I suppose you overlooked in-flight refueling (IFR).

[Todjaeger]

Perhaps some clarification of what I was thinking of, in terms of usage, are in order.

I personally do not doubt that internal jettisonable droptanks could be developed for the F-22 and F-35 as well as any future aircraft that utilizes internal weapons bays. The question of course, is whether or not such development would be worthwhile...

Here are the advantages or possible uses for such a system or systems that basically does the following: Increase in internal fuel carriage, and thus increase in range in a clean configuration.

1. Increased ferry range. This could be done in conjunction with, or in place of external droptanks. At present, the F-22A Raptor has a ferry range in excess of 1,600 n miles with 2 external droptanks of ~600 gal/4,000lb fuel capacity. However, by using external tanks, the F-22 RCS is increased and there is also an increase in drag, resulting in less fuel efficient flight... I doubt that the difference would be enough to for 2 1,000lb internal droptanks to make up for the difference, but the Raptor (and possibly the JSF as well) might well be able to carry a greater weight in an internal droptank. AFAIK the reason the JSF and Raptor can only carry 1,000lb internal bombs has to do with the physical dimensions of the ordnance, with a 2,000lb bomb not fitting into the slots available in the internal weapons bay. The slots themselves I believe are rated for greater weights than 1,000lbs each.

For the F-22 specifically, even carrying internal drop tanks, the fighter would still have some air-to-air armament in the form of the AIM-9X carried in the side weapons bays, as well as possibly still having room internally for 2 AIM-120-C/D/etc. A combination such as this could increase the striking range for the F-22 from a ground base or orbiting AAR. In this sort of configuration, I could see an F-22 engaging in a form of deep strike, decapitation mission vs. AEW aircraft.

This also applies, to a lesser extent to the JSF, depending on exactly how the tanks and armament is fitted to the aircraft. However, for the JSF, this could have even greater utility since the JSF is going to be far more widely deployed, and many of the countries that will be fielding the JSF have little or no AAR capability, nevermind the AAR capacity the USAF has at present.

In short, the idea is to give a boost in the radius of action to the F-22/F-35 etc while maintaining a clean configuration to allow limited and targeted attacks or strikes. This would be similar to the opening sorties of an air campaign where the objective was to roll back the opponent's IADS.

Hope this makes my thinking a little more clear...

-Cheers

[weasel1962]

Deleted

[winnyfield]

The question of course, is whether or not such development would be worthwhile...

-Cheers

No I don't think it would be.

The range and fuel capacity of the F-35 is a vast improvement over 'legacy' aircraft (eg F16, F18). If there are ambitions for extra fuel carriage, conformal tanks are more likely (something Israel is pursuing).