Termyn8or
Posts: 18681
Joined: 11/12/2005
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"and an unstable aircraft can pull the tight turns etc, but is practically beyond human capabilities to fly safely and normally. "
Indeed. But there is another factor coming into play with this maneuverability, G force. They are already deconditioning pilots in a centrifuge, and giving them inflatable pants to try to keep some blood in the brain during hard maneuvers.
Many have blacked out, some have died. Lots of planes now have a system that will level the plane off automatically if it is in a dive for more than a predetermined number of seconds.
I think we will see a trend toward drones in the future. The technology does exist and has been tested. However the demands of a fighter pilot might not be met by current technology. The interface would have to be extensive.
As far as any doubts about hydraulics though, observe the hydraulic schematic of a Turbo-hydramatic 400 automatic transmission used in GM cars and trucks though a few decades. That system controls the shift points and converter dump, and passing gear and everything every bit as well as a computer could. They are considered to be the best three forward speed automatic transmission in the world, and at least one foreign auto maker actually bought them for their V12 sportscars. IIRC Rolls Royce uses,or at least used to use them.
If anyone expresses interest I will scan the schematics and upload them somewhere. I have studied it, and read the corrollary and understand it. I found it fascinating, and I am impressed.
It was designed in the 60s. The valve body is the same thing as a circuit board, it is just a different kind of circuit. It literally functions as a basic analog computer. It has inputs, and carries out actions based on those inputs. When governor or vacuum modulator pressure changes, a piston, called an accumulator moves proportionally. This is analogous to a register in a microprocessor. Inside the piston are other pistons, and once the main piston moves, it passes ports which then start or stop pressure on certain elements of the accumulator. This acts as a schmitt trigger, so that once it shifts, it is reluctant to shift back. It can be persuaded to do so though, by the main inputs, which are calibrated hydraulic pressures dependant on manifold vacuum and vehicle speed. It's passing gear is also faster and more effective being the only electrical input to the system. Floor it and the switch closes which puts it into like an "emergency" mode and provides maximum acceleration.
Really, nobody seems to think about it this way, but you can almost do anything with hydraulics that you can with electronics, it is not as easy of course, but it can be done.
Of course the control circuitry of the "analog computer" that is strictly hydraulic will not be light. It is probably more maintenence, but it is more of a sure fire system.
This is no piece of cake either, we are talking feedback, and totally hydraulic strain guages on the actual operating linkages. The feedback is not easy. And then to factor in the air load makes it look easy because factoring in that one last parameter would give the Cray a headache.
So I think that they are taking the easy way out in using electronics. I could see for the weapon systems of course, but for basic flight control I just don't think it is a good idea. There is a reason we do not have electronic power steering in cars. The system has been designed and built, but never marketed.
In an electronic power steering system, one bipolar transistor can short out and cause death. That is near impossible in a hydraulic system. You cannot see on a molecular level, what shape that transistor is in, but hydraulic valves and such can be inspected.
T
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RE: Your Taxdollars at Work ( Who needs enemies? ) - 
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