Last night a heck of a lot of quotes about 'automatic' and manual (never well explained - only just those words) were interspersed in many quotes collected but now lost - probably a good thing because it was just confusing when test pilots talked about two modes; or ordinary non-test pilots talked about it. Anyway as mentioned 'auto-throttle' is standard. My brain hurts right now to even know what that means in practice. Also there is no direct connection between throttle and engine - all done by computer control laws. Here are some clues:
JSF Active Inceptor System (AIS)
ACTIVE STICK & THROTTLE FOR F-35
Joseph Krumenacker NAVAIR Flight Controls / JSF Vehicle Systems 16 October
2008
"...Reconfiguration for AIS Degraded Modes...
...AIS Modes & Fault Accommodation
• Each Inceptor has three primary control modes:
– Active: sensed grip force is used to actively position the inceptor according to the programmed force vs. position characteristics
• Flight Control Laws use inceptor position as pilot command
– Passive: motor drives disengaged, stick springs provide fixed linear force gradient, throttle has fixed friction & no detents
• Used upon unrecoverable error with motor drives
• Flight Control Laws use stick forces and throttle position as pilot command
• Both stick axes will maintain like mode (if one axis downgrades passive mode, other axis will be place passive mode)
– Jammed: inceptor position is fixed
• automatically detected by software
• Flight Control Laws use inceptor force as pilot command
• jammed throttle requires some Control Law reconfiguration
Throttle:
– Variable aft & forward end-stops (e.g. STOVL mode is different from CTOL mode)
– AB gate (when STOVL system is not deployed)
– Launch gate (CV only)
– STOVL center detent (zero commanded acceleration)
– STOVL on-ground power braking force gradient
– Back-drive
• Auto-Throttle Approach (all variants)
• STOVL Decel-to-Hover..."
http://www.csdy.umn.edu/acgsc/mtg102/SubcommitteD/F35 AIS Krumenacker SAE 081016.ppt (13.4MB)
Tailored to Trap 01 Dec 2012 Frank Colucci
"F-35C control laws give Navy pilots Integrated Direct Lift Control for easier carrier landings, and they open the door for future landing aids.
Joint Strike Fighter (JSF) test pilots in July [2012] began using an Integrated Direct Lift Control (IDLC) scheme meant to improve approach performance and reduce pilot workload in carrier landings. Tailored control responses in part differentiate the carrier-based F-35C from its runway and small-deck siblings. Lockheed Martin test pilot Dan Canin at Patuxent River Naval Air Test Center, Maryland, explained, “What IDLC does is improve the flight path response of the airplane, allowing the pilot to make almost instantaneous corrections to glideslope while maintaining a constant angle of attack.”
“The landing approach in the F-35C is flown with the stick only,” noted Canin. “The throttle is automatic.” IDLC may someday facilitate hands-off landings and other possible F-35 shipboard enhancements....
...“With IDLC, we change the symmetric deflection of the flaps and the ailerons in response to pitch and throttle commands by the pilot. The glideslope response is immediate, and doesn’t require a speed or alpha change. This is a tremendous advantage over a stiff-wing airplane.”....
...“It’s an integral part of the flight control system and responds to the pilot’s normal stick and throttle movements, without requiring a separate control.” The flight control system also compensates for the pitching moments induced by the lifting surface deflections — F-35C ailerons pitch the airplane on approach almost as much as the big horizontal stabilizers — to maintain the proper angle of attack.
IDLC is commanded by an Approach Mode Control button on the F-35 active inceptor stick. “You really could have done this with any other airplane,” acknowledged Canin, “but the implementation would have been more complicated.” He added, “It’s easier and cleaner to do this with a flight control system that’s naturally a pitch-rate-command system.
Flying With Feeling
The triplex-redundant flight control system of the F-35 has flight control laws embedded in three identical, independent Vehicle Management Computers (VMC) made by BAE Systems in Endicott, N.Y. Corin Beck, BAE product director for fixed-wing control systems, said typical quad-redundant legacy flight control systems route all interfaces back to a central Flight Control Computer. The F-35 VMCs are separated for survivability and work as network controllers. They interface with aircraft sensors, active inceptor controls, actuators, and utilities and subsystems, and they provide a bridge to the F-35 mission system network....
...BAE Systems Electronic Systems in Rochester, U.K., also makes the F-35 active inceptor system including the active throttle quadrant assembly, active side-stick control assembly, and an interface control unit. The motorized inceptors transmit pilot inputs to the F-35 fly-by-wire flight control system and give the pilot tactile cues with resistance ramps, gates and stops to provide aircraft “feel” and warnings. Unlike traditional springs, stick shakers and other mechanical force-feedback mechanisms, the motorized sidestick varies feedback forces with aircraft condition.
The throttle is likewise back-driven to give the pilot situational awareness about the energy state of the airplane and the corrections being made. If or when the pilot breaks out of Approach Mode, the throttle position is synchronized to the engine thrust request (ETR). “If the throttle is physically jammed, the approach mode will still work. One of the redundancy features of the airplane is that the physical throttle linkage is no longer required,” Canin said.
Engine thrust request is the driver for IDLC surface deflection. The Moog electro-hydrostatic actuators that move the F-35 control surfaces promise survivability and maintainability advantages over more conventional hydraulic actuators. They also provide slightly greater bandwidth than hydraulic actuators for IDLC. However, Canin observes, “We could have done this with hydraulic actuators. The magic is in the control laws.”...
...Unlike production F-35s, the JSF SDD aircraft have a Flight Test Aid (FTA) system that allows pilots to evaluate different control gains and mechanizations in flight. Using FTAs, for example, pilots were able to look at IDLC gains of 150 percent, 200 percent and 300 percent of the original baseline gain, eventually settling on 300 percent.
“We can do this safely, because if we ever see anything we don’t like, we can press a paddle switch on the stick to put us immediately back to the baseline control law,” said Canin. Since F-35 production software and test software are the same, LRIP aircraft will actually have the FTAs incorporated but no FTA switch with which to activate them.
All three variants of the F-35 provide some measure of IDLC. “Glideslope is always important,” observed Canin. “Anything you can do to improve flight path control on approach is a good thing. Wave-off performance is also improved with IDLC, since it can stop or reduce your rate of descent while you’re waiting for the engine to spool up.”
The IDLC function is not identical in all the three F-35 variants, however. “The IDLC gain is much higher in the C-model than the other two,” said Canin. “We only have one release of software for the three variants. It configures itself when it wakes up and discovers which type of F-35 it’s in.” The F-35B does not use IDLC at all in jet-borne (vertical landing) mode, when aerodynamic control surfaces are fixed.
Even with its innovative flight controls, the F-35C, from the pilot’s perspective, is relatively conventional coming aboard the carrier. “Determining where you are with respect to lineup and glideslope is all visual,” acknowledged Canin. “For lineup, you look at the ship and line up on centerline … easy enough if the ship’s heading is steady, but tricky if the ship is wallowing,” noted Canin. “As for glideslope, you have to watch the meatball and see small deviations. Then you have to put the ball back in the middle, with the right rate of descent so it stays there. None of that’s changed with this airplane, but what we’re giving the pilot is more responsiveness and bandwidth to do that.”
The F-35 uses a BAE Helmet Mounted Display (HMD) instead of a conventional Head-Up Display (HUD). Like a classic HUD, the HMD shows the pilot a flight path marker (or velocity vector), with a bracket to indicate if the aircraft is “on speed” or flying fast or slow. Meanwhile, a caret moves up or down in reference to the flight path marker to give an acceleration-deceleration cue.
Ashore, when the aircraft is on glideslope, the pilot simply puts the flight path marker by the meatball and the aircraft stays on that glideslope. “At the ship, since the landing area is moving through the water, the pilot needs to put the flight path marker out in front of it. He needs to put it where the landing area will be when he gets there, which again requires judgment. A better system would be put the velocity vector into the moving reference frame of the boat,” Canin said.
Though not currently part of the F-35 plan, implementing a “ship-referenced velocity vector” (SRVV) would allow the pilot to put the SRVV on the intended touchdown point to hold glideslope. “All we would need to know from the ship is its current velocity, so we can put the airplane symbology in that reference frame,” Canin said.
Readily rewritten control laws have other possibilities. “With the current flight control law, the pilot commands pitch rate with the stick, and uses that pitch rate to establish a glideslope,” noted Canin. “There’s no reason, though, why the flight control system couldn’t establish a baseline glideslope, and allow the pilot to apply control stick pressure to command tweaks around that glideslope in response to ball deviations.” A “glideslope command” mechanization of this sort is not in the baseline airplane now, but is an example of the type of changes that could relatively easily be incorporated in the F-35 control system...."
Avionics Magazine :: Tailored to Trap
JSF Live Fire Test—Pilot-in the Loop Simulator Testing Jeffrey Andrus 2010 Spring
"...Test Conclusions...
...The use of MTL simulator testing at this stage in the test program has proved valuable as the JSF Live Fire Team starts a complex and thorough test program for the three F-35 variants. Simulator testing examines the response of the pilot and F-35 aircraft to failures that represent possible damage modes associated with encounters with ballistic threats...."
http://www.bahdayton.com/surviac/asn...O_Spring10.pdf (no longer available)
3 page extract of above here:
http://www.f-16.net/forum/download/file.php?id=19800 (PDF 0.5Mb)