J-20... The New Generation Fighter III

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D

delft

Brigadier
The weight of the hydraulics also depend on the speed of extension of the air brake as well as on the air density and the speed of the aircraft .
 
D

delft

Brigadier
Engineer said:
It also depends on the hydraulic pressure. The higher the pressure, the lighter the mechanisms can be made.
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Of course. But the pressure used is given by the state of technology at the time and not the responsibility of the aircraft designer.
 
P

Player99

Junior Member
siegecrossbow said:
I don't think the airbrakes themselves are gonna do any good. If I guessed correctly it is the location/size of the brakes that indicate the plane's role.

One thing we have to consider is that the hydraulics will add extra weight to the plane. This is not a good thing. Wonder what makes it worthwhile.
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So we are sure even with a 5th-Gen fly-by-wire system, the actuators, etc. are still hydrolic? I was under the impression that electric motors are used instead...
 
Blitzo

Blitzo

Lieutenant General
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Player99 said:
So we are sure even with a 5th-Gen fly-by-wire system, the actuators, etc. are still hydrolic? I was under the impression that electric motors are used instead...
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I don't think anyone knows that for sure. I think what seige meant was that as long as there's an extra control surface which needs moving (that is, a massive airbrake), you will always get additional weight due to the machinery necessary to move it.

Player99 said:
Is the J-20 of a fly-by-wire or a fly-by-light system?
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Again we don't really know but the latter is a possibility.
 
N

no_name

Colonel
Fluid power is preferred over electric motors when linear motion against large load is required as opposed to smooth circular continuous motion. They are also less likely to overheat and more forgiving to jams, and can be more distributed in their placements.

FBW and FBL refers to how the control signals is sent to the actuators, not how the actuators are activated themselves. You can have a computer sending flight instructions via electric wires or fibre optics to actuator controllers which then move the flaps using pistons.
 
MwRYum

MwRYum

Major
no_name said:
Fluid power is preferred over electric motors when linear motion against large load is required as opposed to smooth circular continuous motion. They are also less likely to overheat and more forgiving to jams, and can be more distributed in their placements.

FBW and FBL refers to how the control signals is sent to the actuators, not how the actuators are activated themselves. You can have a computer sending flight instructions via electric wires or fibre optics to actuator controllers which then move the flaps using pistons.
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IIRC, fibre optics have the advantages of higher bandwidth and one less weakpoint to the overall system platform when deal with EMP protection, but fibre optics cable have the disadvantage of being a delicate material as well.
 
N

no_name

Colonel
Actually the PLAAF J series planes classifies quite well in terms of generation by number:

number under 10 are for 3rd gen and prior, such as J-6, J-7, J-8
numbers between 10 and under 20 are for 4th gen, such as 10, 11, 15
numbers 20 and under 30 can be for 5th gen, such as J-20. (10 possible slots should be more than enough)

and so on (ie 30-39 for 6th gen)
 
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