Latest and greatest (F117, B2, F22*) buzz Rose Parade!, page 1
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Topic started on 1-1-2004 @ 05:05 PM by crayon


U.S. Welcomes 2004 Peacefully But Still Tense

Security was tight. Lots of cops and such. And this is only the Rose Bowl. I fear what is going to happen with some of the bigger bowl games and the Super Bowl. Could take hours just to get into the stadiums once you get in line.


* Oops, yeah, F22, not JSF

[Edited on 1/2/04 by crayon]


reply posted on 3-1-2004 @ 08:44 AM by Knowsstuff

Hmm, I did not think that a highly maneuverable aircraft needed a computer. P-51 Mustang? Very maneuverable, no computer. Though it did have problems in negative G situations, thank the carburetor for that.


the Mustangs used in combat were powered by the Packard V-1650. a license built Rolls Royce Merlin engine, which was fuel injected, and didnt have a carburetter. which meant it could fly upside down and everything!


The F-117 is a fly-by-wire system, I believe. Which would mean a computer is necessary to control the aircraft. The A-10 is redundant hydrolic control with a backup manual control system, just in case you lose hydrolics. So, no high-tech computer needed. The reason why the A-10 is so maneuverable is its small size, compared to a passenger jet, and its low speed.


Crayon, trust me, i am An Airframe Systems and Structures Technician for the Royal Air force. i was previously a Licensed Airframe and Propulsion Technician for civialian helicopter companies. i have worked on all sorts of aircraft, from small utillity helicopters to large scale off shore oil and gas support helicopters, also passenger jets, air to air refuelers and combat jets.

Fly by wire or not, all modern aircraft are controlled by a computer to some degree. you could not fly a modern combat jet without the assistance of the computer. all the minute control inputs from the computer are what keep the aircraft stable inflight. theese inputs are made so quickly a pilot couldnt possible do it, so the computer does it for him. try to look into the British aerospace Jaguar Advanced Control Technologies aircraft from the 70's thats when the brits were using this technology to make their combat jets stable and simple to fly yet agile and manouverable to fight and bomb with.

size has nothing to do with manouverability, most light aircraft are very benign in their handling since they are designed to be easy to fly, thats down to design of wings and control surfaces etc. think of the Tomcat on the other hand, a 28 ton FIGHTER jet! it is one of the most highly manouverably aircraft in the world. or better still, the B1 Lancer! a supersonc bomber that is almost as manouverable as a fighter jet! thats all down to advanced control technologies. the F117 is Physically impossible to fly without the help of the computers because the stealth design is not compatible with flight charachteristics, so it is essentially Forced to fly.


Cranfield University

quote from above web page, from Cranfield university, a specialist university for Aeronautical Engineering.

"(iii) Autopilot and flight director systems provide automated piloting commands to relieve the pilot of mundane tasks, to control the aeroplane when conditions may not be favourable for normal pilot control and to provide extreme control precision which may be difficult for the human pilot to achieve. Clearly, the flying qualities performance requirements for this type of controller are different and since there is no human pilot in the loop, handling qualities considerations do not apply. The large majority of autopilot systems provide various automated flight path control functions and facilities for holding variables like height, Mach number, attitude, etc. at constant pre-set reference values."




The slow response of a passenger jet is more for passenger comfort than lack of a computer to control the plane. And the A-10 only has 1 passenger, and the pilot should know what they are getting themselves into if they yank on the stick.



i never said that an airliner didnt have a computer onboard, and i know its for passenger comfort. actually, its because the aircraft isnt designed to take the loads associated with high speed manouvering, but it is designed like this because there is no need for the aircraft to be highly manouverable. the computer onboard the aircraft is usually programmed NOT to allow movement like that. take for example the new Airbus A318. All Airbus aircraft a fly by wire, side stick controled. there is no phisical link from the cockpit controls to the control surfaces. it makes now difference how quicky you move the stick, it will not operate the control surfaces out with the parameters of the aircrafts flight envelope. it also wont allow you to stall the aircraft, or let it enter a spin.


[Edited on 3-1-2004 by Knowsstuff]

[Edited on 3-1-2004 by Knowsstuff]


reply posted on 3-1-2004 @ 12:59 PM by crayon
Originally posted by Knowsstuff
the Mustangs used in combat were powered by the Packard V-1650. a license built Rolls Royce Merlin engine, which was fuel injected, and didnt have a carburetter. which meant it could fly upside down and everything!

In June 1940, Packard was requested to undertake the production of some 9000 Merlin XX engines. It took just three days for the company to respond positively but on that proviso that some modifications would be made to the powerplant to enable American accessories such as carburetors, fuel and vacuum pumps to be utilized. So I guess we are both right, though I find no mention of the V-1650 engine anywhere.

From:
P51
Crayon, trust me, i am An Airframe Systems and Structures Technician for the Royal Air force. i was previously a Licensed Airframe and Propulsion Technician for civialian helicopter companies. i have worked on all sorts of aircraft, from small utillity helicopters to large scale off shore oil and gas support helicopters, also passenger jets, air to air refuelers and combat jets.

Work on any A-10's?
Fly by wire or not, all modern aircraft are controlled by a computer to some degree. you could not fly a modern combat jet without the assistance of the computer. all the minute control inputs from the computer are what keep the aircraft stable inflight. theese inputs are made so quickly a pilot couldnt possible do it, so the computer does it for him.

If you are talking about a computer controling the hydrolic pumps, then I agree with that.
or better still, the B1 Lancer! a supersonc bomber that is almost as manouverable as a fighter jet

When its not crashing.
the F117 is Physically impossible to fly without the help of the computers because the stealth design is not compatible with flight charachteristics, so it is essentially Forced to fly.

Yes, that is why I would not want to fly one of these.
Cranfield University

Great paper. But it talks more about high speed, highly maneuverable aircraft. No mention of the A10, just hints at flight control systems, but that is it.
All Airbus aircraft a fly by wire, side stick controled. there is no phisical link from the cockpit controls to the control surfaces. it makes now difference how quicky you move the stick, it will not operate the control surfaces out with the parameters of the aircrafts flight envelope. it also wont allow you to stall the aircraft, or let it enter a spin.

Yes, fly-by-wire, passenger jet. We are talking about a flying gun though. I know there is someone out there that has some good technical information on the A-10. I keep finding the same stuff, over and over again.


reply posted on 3-1-2004 @ 03:33 PM by Knowsstuff
merlin specifications

page above refers to the Injection type carburetter. not actually a carburetter, only called that as a lay-mans term. 1st generation of injectors injected the fuel into where the carburetter would be. unlike modern injected engines, which are usually directly into the cylinder.



Work on any A-10's?


the Royal Air Force doesnt have A-10's. i dont need to have worked on them to know how it all works, almost all aircraft work on the same principles, there are just variations specific to type. you seem to have A-10 's on the brain though



If you are talking about a computer controling the hydrolic pumps, then I agree with that.


computers dont control the Hydraulic pumps, they are driven from the Accessory gear box of the engine, or main rotor gear box on a helicoper and are controled by servo pressure sensed from pressure in the system. when the system pressurises it moves the pump off stroke. keeping the pressure up but cutting off the flow. or in the case of a fixed delivery pump, the fluid goes through an automatic cut out valve, when sysem pressure is reached. computers control the actuators on the control surfaces by way of moving a small servo valve on the body of the actuator.

as for your comment on the B1, all aircraft suffer losses and this is by no means a reflection of how good the aircraft is at performing its function.

[Edited on 3-1-2004 by Knowsstuff]


reply posted on 3-1-2004 @ 11:17 PM by Revolutionary
It's OK, Crayon... I have A10s on the brain, too.

No, they are not fly by wire. Are the hydraulics MONITORED by computers, yes, but not controlled by them (well, not as in FLY BY WIRE control, anyway).

When the hydraulics fail on an A10, manual control is possible because the pressure on the control surfaces are light enough for a man to use brute strength to maintain control. Much like a small Cessna, but the controls are much "heavier" on an A10 compared to a C152.

The A10's slow-flight characteristics are possible because of it's main wing type which include a decent amount of
dihedral. See this picture:




Knowsstuf said:
the Royal Air Force doesnt have A-10's. i dont need to have worked on them to know how it all works, almost all aircraft work on the same principles, there are just variations specific to type. you seem to have A-10 's on the brain though


This statement troubles me. Yes there are basic prinicples, but one can not be this general with respect to complex machinery. I "knowsstuff" about computers, but I don't proclaim to know anything about Crays. But hey, they all work on the same principles, right? At least you know stuff about how a control surface is actuated by a hydraulic system.
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