How do variable-sweep wing planes keep their ordnance and fuel tanks straight?

Posted by Tabard18@reddit | aviation | View on Reddit | 6 comments

[-]

FelisCantabrigiensis@reddit

The pylon mounts rotate - and that mechanism is added weight and complexity, another reason why variable-sweep aircraft are not usually the preferred design today.

Some variable-sweep aircraft keep most or even all of their ordnance on the wing root or glove section (which doesn't move) or the fuselage, to avoid most or all of this problem. You can see this F-14 has its AIM-7 on a pylon that projects from the side of the fuselage, not the wing: https://www.heatblur.se/F-14Manual/weapons.html#aim-9-sidewinder

[-]

Tabard18@reddit (OP)

Do you know if they are driven or rotate freely? Most payloads are aerodynamically stable and will naturally point into the wind so you might get away with it

[-]

davidsdungeon@reddit

On the Tornado it is all done through linkages, so as the wing geometry changes the pylons remain at the correct angle.

Cool story time:

Also on the Tornado the electrical connections for the pylon were situated in the leading edge of the wing, and could be a bit of a pain to get fitted and loomed correctly. Once fitted we would then need to get the secondary flying controls into a mismatched configuration of flaps up but slats down, to allow the wings to be swept back with someone sat on top of the wing checking that the cables were clear of the aforementioned linkages and there was no fouling.

It could be at times a bit jerky as you didn't want to go too quickly in case there was any fouling, and controlling the movement by the lever in the cockpit wasn't the easiest. The best way was to select the wing sweep lever fully back and then slowly apply the hydraulic power from the rig, it a was much smoother motion.

I once had to do it on a RH outboard, but it was done from APU power. That was not much fun as I was being blasted from the APU exhaust.

[-]