Hai expert aircraft <span title="aerodynamic/avionic/aircraft">aerodynamic/avionic/aircr...</span> engineer(s)..?

Question

1:

do you think aircraft stability at medium-to-high AoA

(20 to 80 deg AoA) doesn't have anything to do with the

aircraft's underbody design ? or just leave it to FBW control to do the rest ?

2:

do you think aircrafts with many flat planes

at most of its underbody and

small number of (or doesn't have any) vertical planes

(such as F-117, YF-23, B-2)

can be pulled to medium-to-high AoA (20 to 80 deg AoA)

(and stabilized it with/without the help of FBW) ?

3:

do you think thrust vectoring

is mandatory in question 1 & 2 ?

4:

do you think aircraft with complex medium/high

angle of anhedral+dihedral wing, such as phantom works's "bird of prey"

can be pulled to

medium-to-high AoA (20 to 80 deg AoA)

(and stabilized it with/without the help of FBW)

?

thanks a lot ;)

Answer 1

Modern military combat aircraft are ALWAYS unstable.  This is necessary for enough maneuverability to survive in combat or because stealth design is unstable or both.  FBY is required ALWAYS required.  Only a computer can keep up with the control inputs needed.  Sometimes, counter-intuitive control inputs are needed.  Only a computer can do this.

Answer 2

1) Yes, aircraft stability will be affected by under body design. There may be some aerodynamic inter-action, but not enough to warrant FBW handle it.

2) You need FBW. The aerodynamic inputs needed to stabilise the aircraft would be too fast and far too complex for the human body to react.

3) In question No: 2 yes. The thrust vectoring would a part of the inputs needed for stability, mainly to counteract the missing vertical surfaces.

4) No need for FBW - such designs (dihedral and anhedral) provide inbuilt stability during flight, throughout the designed flight envelope.

Answer 3

Intro: I am no expert, any &quot;expertise&quot; is in avionics.

1) The stability depends on the vectors of aerodynamic center and center of gravity. So cant really say that the undebody design influences it to such extents.

FBW is just a transmission system, it doesnt have much role in the aircrafts inherent stability.

2) The MiG-29 has lots of flat planes and no FBW, but it is highly agile and capable very high AoA maneuvers, including the Cobra.

3)  Desirable, but not mandatory. Once again the MiG-29 is the perfect example.

4) The Bird of Prey is a stable design, so the FBW is just a facilitator. And I doubt if there is a high AoA aircraft with significant anhedral/dihedral, it is not logical. Anhedral/dihedral configurations are for roll stability and roll stability inhibits maneuverability.