F-14B slows down in full wing sweep?

[PatientMental76]

I noticed when just cruising in auto mode at about half sweep & then if the wings are manually fully swept back without moving the throttle the plane slows down? Is this correct? I would have thought it has less drag & it should be easier to speed up & be able to throttle down a little bit while maintaining the same speed to save fuel! Anybody know why this is happening?

[Hector45]

Without changing speed but putting wings back you are reducing lift therefore the autopilot has to increase the AOA to maintain altitude which will cause you to slow down. At least this is how I understand it, someone correct me if I'm wrong.

[TLTeo]

Yep, correct. The higher the wing sweep, the more AoA you need to generate a given amount of lift, especially at slow speeds. If you're going to keep flying level, increasing AoA will increase induced drag so if you don't compensate for it with power the aircraft will slow down.

There's a reason why airlines don't have wings swept back 68 degrees

[AndyJWest]

For any given set of conditions (weight, IAS, MACH etc) there will be an optimum sweep angle. It is the job of the auto control to match this as best it can. I'd be surprised if a human pilot could do significantly better.

[draconus]

14 hours ago, PatientMental76 said:

I would have thought it has less drag & it should be easier to speed up & be able to throttle down a little bit while maintaining the same speed to save fuel!

What kind of speed? GS, TAS or IAS?

To save fuel climb high around 32k ft, IAS around 230kts, you should be around 10 units AoA and leave wings on auto.

[r4y30n]

The purpose of the auto sweep schedule is to minimize total drag from the wings at all times. If you’re changing sweep away from the auto position you’re pretty much guaranteed to increase drag.

That’s why you sweep them back before the break, to maximize drag for the turn.