Forum: F-16 Design & Construction

Every jet flown in the USAF has a pilot "voting." The only one directly connected to the flight controls is the tweet... The "voting" analogy tends to annoy me. Some dudes say "I want the ability to rip the wings off, if I need to..." Well, that's kinda like voting for last years president... YOU CAN'T and do anything good with it. If the FLCS doesn't let you do it, the jet (either due to aerodynamics or structurability) can't do it either...

Cylon

F-16.net Sponsor

Amen, brother!

I was dead set against the F-16 FLCS control laws until I flew the thing.

Turns out that GD had set very reasonable limits on what we could 'command'. In fact, for the ham-fisted troops, 'it was a good thing'.

Few of us could 'feel' the edge of the envelope. The masses could not. I would fly with folks in the A-37 and the family model of the F-16 and ask them if they could 'feel' the vibration, buffet, burble, whatever. Most of the nuggets could not. I COULD! Dounno why, but God had blessed me with 'touch'.

Hence, one day when I felt a loud thump after taking off from a slushy runway with icing potential, I simply kept the throttle where it already was. I could feel the vibrations. So far, so good, and I informed rest of the flight I was RTB. Never touched the throttle again until the flare - used speed brakes a lot.

Shut down and crewchief was shaking his head after looking into the intake. Had about 50-60 blades either bent or destroyed. Good old P&W had saved my sorry butt once again.

Many pilots would have pushed the power up because they couldn't feel the vibes.

Oh well, if the flight control laws give you all that the jet can do, then that's fine with me. Oh sure, would nice to have the 'Chuck Yeager mode' for a very few hot sticks. OTOH, I felt very comfortable pulling for all I could in the Viper, knowing that I was getting the best that the plane could give me.

later,

P.S. Habu-duece, the rate problem ain't a rate problem in the Viper conrol laws as far as pitch is concerned. The roll rate can get you into trouble if you are heavy and are not in Cat3 position on that magic switch. But in either case you will not get into a deep stall. The way to get into a deep stall is to pull to about 80 degrees of pitch and let speed decay while pulling back real hard at the end game - speed below about 100 knots. If you get too much higher pitch, you will do a tail slide. Trust me on this. I did it one day while looking over my shoulder at the other guy when the slow speed horn came on. Was too late to do anything. The sucker was about a perfect 90 degree climb, then backed down thru the contrails and all the FLCS panel lights came on. Nose came thru just dandy and I was flying again at about 90 knots.

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

Another point to remember is the throttle setting is a "Request"

If the engine control doesn't think the "request" is made a proper point inside the flight envalope, it is altered or ignored.

Unless, that is, you select "SEC"...................Then it will take pilot "reqests" more seriously, unless it is for augmentor, which is inhibited during "SEC".

If that "request" is not complied with (throttle positon does not match thrust selected) then the jet transfers to SEC.... This is bad if the mechanical linkage is bad. At that point you cycle it back into norm. In SEC the engine is primarly based on physical throttle postion (cable connection to throttle). Besides, name a jet that the fuel flow into it is not a "request." You'd have compressor stalls otherwise.

Cylon

Ahem,

The original F-100 engine back in the Pre-cambrian days didn't have DEEC, only EEC. We had the 'direct fuel input via throttle (PLA)' feature when in BUC (backup fuel control). Was like the engine in the T-33, push fast and stall and/or overtemp. But the sucker worked well.

In fact the original Thunderbirds used to start in BUC because it reduced that ear-piercing howl when the jets were pointed at the crowd.

After an ejection or two due to bad motors and the troops 'rushing' things on the re-light or when switching over to BUC, a few of us decided to see for ourselves............ The P&W tech rep told us we would have no problems if we just took it easy. So a few of us that had flown the T-33 went to a jet and started the thing right up in BUC. Actually got it going quicker than normal, but had to watch PLA and temp like a hawk, errr Falcon. Secret was to 'push' up the temp with throttle very smoothly and not reverse the throttle if temp was increasing too rapidly. In that case, just stop and resume pushing up once temp stabilized.

A supervised BUC start was added to the syllabus and also to our training cycle every few months or less.

out,

P.S. got to see the 'birds this weekend. The USAF wimped out and the maneuver that the guys crashed while attempting looked to have an apex a thousand feet higher than necessary or even last year's version. The guy had to just about do a steady 20 degree dive for awhile just to get back to 300 feet or so above the runway.

The throttle is not that sensitive in SEC, unless you have low airspeed / inlet temperature. That is true if you are operating on a test stand that provides ambient pressure to feed the engine (which would simulate low mach/inlet pressure and temperature). l'll give you the idle (mil)-lockout condition. This is the same reason everyone thinks the T-38 engines are "touchy." Only when you get below safe mach numbers at high altitude / low inlet temperature and pressure do you have to "cuddle" the throttle.

I guess it just backs up the bad anology of "voting" for thrust. Just like with the FLCS, if you want to "override" the vote you made, something is already screwed up and bypassing the system won't get you anthing extra.

Cylon

Forum: F-16 Design & Construction

F-16 FLCS control - "voting" for thrust