While I’m randomly reading the block diagram of F-16 DFLCS, I noticed that the FLCS will actually switch to pitch-rate feedback (blended with AOA > 10°) if dynamic pressure is below 600(?) psf, and either ALT FLAPS switch in EXTEND position or AIR REFUEL switch in OPEN position, and most weirdly, in Standby Gains. Here’s the source:
Closer look:
(F-16 Digital Flight Control System Functional Block Diagrams. Data obtained from Lt. Bruce Peet, F-16 System Program Office, Wright-Patterson OH.) quoted in DTIC ADA202599 and DTIC ADA189675.
Yes the text is very hard to recognise but it can be decoded as:
NOTE 1. Switch activates by ANY of the following methods:
- LG Handle in DOWN position
- Standby Gains & [Fwd or Aft ALT FLAPS Switch in EXTEND position] & qc < 600psf
- Standby Gains & [Air Refuel Switch in OPEN position] & qc < 600psf
Whether it’s 600psf I’m not sure, but it’s the closest to 400kts airspeed. This switch genuinely switches between Nz feedback and pitch-rate feedback (blended with AOA > 10°) with a first order filter used as a fade-in function. Notice that Standby Gains requirement, which is not present in the HAF Dash-1 manual.
I wish anyone could check the CM-1 manual, but I’ll just quote the HAF CJ-1:
Takeoff and Landing Gains
The FLCS is in takeoff and landing gains with the LG handle in DN, the ALT FLAPS switch in EXTEND (below 400 knots), or the AIR REFUEL switch in OPEN (below 400 knots).
So my question is whether the above quoted statement stands true for F-16CJ and F-16CM, since I remembered in BMS that there’s no such (400kts) requirements.