F-35 vs J-20

The F-35 compared with other modern jets.
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wrightwing

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Unread post26 Mar 2017, 22:51

Don't forget that any SEAD/DEAD mission would also include MALD/MALD-J, as well as deception jamming/electronic attack of the Tor/Pantsyr systems, that are trying to intercept SDB/JDAM/JSOW/JASSM/etc....
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weasel1962

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Unread post27 Mar 2017, 10:56

One area of R&D to look at countering massed PGM attacks are lasers. USN already deployed Kratos to counter swarming drones. If it can counter swarms, then massed PGMs as a target set won't be too far off. China’s Poly Tech was seen deploying a 50-70W laser “silent hunter” recently at IDEX 2017 which is significantly higher powered than Kratos.

Also adding an Arian disclaimer that these are manufacturer claims, read at your risk etc etc etc…..
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ricnunes

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Unread post27 Mar 2017, 11:07

weasel1962 wrote:One area of R&D to look at countering massed PGM attacks are lasers. USN already deployed Kratos to counter swarming drones. If it can counter swarms, then massed PGMs as a target set won't be too far off. China’s Poly Tech was seen deploying a 50-70W laser “silent hunter” recently at IDEX 2017 which is significantly higher powered than Kratos.

Also adding an Arian disclaimer that these are manufacturer claims, read at your risk etc etc etc…..


Yes, I also believe that at some point into the future that "Lasers" or other types of "energy directed weapons" will be the way to go.
But independently of the evolution of such weapons into reliable and powerful weapons one thing still remains the same - You have to be able to detect and track the target(s) in order to shoot it(them) down and it doesn't matter with what you're shooting at it, doesn't matter if you're shooting with a gun, a missile or a laser.

Resuming if those PGM's are stealth and thus hard to detect it will be hard to shoot them down even with advanced weapons such as laser or any other kind of "energy directed weapon". Basically you can only shoot what you can "see".
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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weasel1962

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Unread post27 Mar 2017, 11:23

Agreed. At the same time, we all know stealth does not mean invisibility. It just means having to be a lot nearer to detect. Ground based radars have an advantage cos these can be much higher powered. Then, bigger radar target for ARMs which goes back to lasers/CIWs defending these and so on.

Faster PGMs also mean shorter time to target. That's why Boeing did a lot of work even for unpowered SDB-1s to reduce flight path decreasing flight time. So is Raytheon. Also, could mean powered versions like spear CAP 3 may be more effective than unguided ones if the time to target is a critical factor. Maybe increased munition weight, trading off range, to add armor to munitions increasing laser resistance may be something we'd see beyond just stealth. Just need more defense $$$. Any wonder why defense contractor shares tend to go up?
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jessmo111

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Unread post28 Mar 2017, 01:15

Back to topic. This fat sow of a fighter will never be able to turn and burn with an F-35! Its seriously underpowered for its massive size. The Chinese have been running a disinformation campaign for years trying to get you to believe this. They want you to believe that the plane is in the 30k weight class (ie the weight of an F-35). This plane is closer to the F-111s weight class, with an F-15 level engine. If the J-20 can keep up with the F-35 in a turn, then I have land to sell you, and this woman can beat me in a foot race.
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neurotech

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Unread post28 Mar 2017, 04:09

jessmo111 wrote:Back to topic. This fat sow of a fighter will never be able to turn and burn with an F-35! Its seriously underpowered for its massive size. The Chinese have been running a disinformation campaign for years trying to get you to believe this. They want you to believe that the plane is in the 30k weight class (ie the weight of an F-35). This plane is closer to the F-111s weight class, with an F-15 level engine. If the J-20 can keep up with the F-35 in a turn, then I have land to sell you, and this woman can beat me in a foot race.

The F-111 is a lot heavier than a F-15, and had TF30 engines that are significantly less powerful than the F100 engines in the F-15.

VADM. Tom Connelly famously quoted the problem with the F-111B is "There isn't enough thrust in Christendom to fix this plane." meaning to make the jet work as a fleet defense fighter. Does anyone think the J20 will be any different?

Remember that thrust vectoring doesn't make a jet magically agile, if it don't have the thrust/weight ratio. The F-22 will loose airspeed/energy pretty quick in high alpha maneuvers, just like any other jet. At the airshows, the F-22 does those tight maneuvers at low speed, and able to use the high thrust/weight ratio for staying in the air in the high-alpha state.
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Unread post28 Mar 2017, 07:17

neurotech wrote:
jessmo111 wrote:Back to topic. This fat sow of a fighter will never be able to turn and burn with an F-35! Its seriously underpowered for its massive size. The Chinese have been running a disinformation campaign for years trying to get you to believe this. They want you to believe that the plane is in the 30k weight class (ie the weight of an F-35). This plane is closer to the F-111s weight class, with an F-15 level engine. If the J-20 can keep up with the F-35 in a turn, then I have land to sell you, and this woman can beat me in a foot race.

The F-111 is a lot heavier than a F-15, and had TF30 engines that are significantly less powerful than the F100 engines in the F-15.

VADM. Tom Connelly famously quoted the problem with the F-111B is "There isn't enough thrust in Christendom to fix this plane." meaning to make the jet work as a fleet defense fighter. Does anyone think the J20 will be any different?

Remember that thrust vectoring doesn't make a jet magically agile, if it don't have the thrust/weight ratio. The F-22 will loose airspeed/energy pretty quick in high alpha maneuvers, just like any other jet. At the airshows, the F-22 does those tight maneuvers at low speed, and able to use the high thrust/weight ratio for staying in the air in the high-alpha state.


Super Agility is hardly a critical factor in a 5th Generation Fighter. Honestly, I hear supporters of the PAK-FA always boasting that it's far more agile than the J-20. Yet, I would be far more concern with the Stealth (RCS) and Sensors of the two. Then low speed agility....
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Unread post28 Mar 2017, 13:56

One must know that carnard is less effective than tail plane under high alpha, because the local alpha of canard is higher than the wing, causing the carnard to stall early. In this case, the carnard generates only drag and no lift or other useful control force. So far, no carnard fighter could handle high alpha (including EF2K, rafale, JAS39). Even the mighty X-31 loses to a hornet in a knife fight when thrust vector is disengaged.

The F-35 is an intersting case. The ability to performe X-31's J-turn (or pedal turn) at a constant 28deg/sec without thrust vectoring is a serious advantage in a conventional one-circle or two-circle fight. The adversary must sustain the same rate of turn, otherwise it will lose. So far, no adversary (including Su-27, Mig-29, J-31, J-20) has demonstrated anything close.

A common criticisms for F-35's high rate maneuver (e.g. pedal turn) is that this maneuver is conducted at high alpha and thus low energy. However, this is not a problem, because F-35's energy recovery is so good that it out-accelerates Su-27 by 20% at subsonic:
viewtopic.php?f=55&t=52510

Even J-20 may be equipped with thrust vectoring and handle some high alpha, will it be able to acheive the same energy recovery? Thrust vectoring does no help to acceleration, IMHO
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Unread post28 Mar 2017, 21:45

This is off topic but as long as we are talking about aerodynamics I've got a question:

Why does the f35 often seems to be at positive AoA during level flight?
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Unread post28 Mar 2017, 22:43

citanon wrote:This is off topic but as long as we are talking about aerodynamics I've got a question:

Why does the f35 often seems to be at positive AoA during level flight?


This is difficult to answer without knowing the flight envelope of the plane. It could just be that its cruising speed is higher than the aircraft it's taking photos with.

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Unread post28 Mar 2017, 23:43

citanon wrote:This is off topic but as long as we are talking about aerodynamics I've got a question:

Why does the f35 often seems to be at positive AoA during level flight?

All aircraft fly at a positive AoA in level flight -- though there is probably a certain amount of arbitrariness about how zero AoA is defined for a given aircraft.
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Unread post28 Mar 2017, 23:55

gta4 wrote:One must know that carnard is less effective than tail plane under high alpha, because the local alpha of canard is higher than the wing, causing the carnard to stall early. In this case, the carnard generates only drag and no lift or other useful control force.

That would be true for stable canard aircraft, but unstable canard aircraft actually keep their canards at a lower angle of attack than their main wing. Additionally, the control surfaces on the trailing edge of the main wing can also contribute to pitch moment.

That said, this is all treating the wing and canard/tail in isolation from the shape of the whole aircraft. Things like the angle of the chines on the nose of an aircraft can greatly affect stability. I'm pretty sure that you could design an aircraft that is stable in level flight with a tail at the same AoA as the main wing.
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Unread post29 Mar 2017, 01:56

count_to_10 wrote:but unstable canard aircraft actually keep their canards at a lower angle of attack than their main wing.


But for unstable canard, since the plane always tends to pitch up, the carnard need to provide a nose down moment to maintain balance, resulting in negative carnard lift. This has a negative impact on total lift.
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Unread post29 Mar 2017, 02:19

Additionally, the control surfaces on the trailing edge of the main wing can also contribute to pitch moment.


IMHO, I have only seen this during take-off and landing, but I have never seen any canard aircraft use the trailing edge of the main wing to trim in a high-G maneuver. Is it due to the fact that the trailing edge of the main wing are designed for take-off and landing only (about 1G), thus the structure strenth is insufficient for high-G maneuver?
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Unread post29 Mar 2017, 02:45

gta4 wrote:
But for unstable canard, since the plane always tends to pitch up, the carnard need to provide a nose down moment to maintain balance, resulting in negative carnard lift. This has a negative impact on total lift.

They don't need to provide negative lift, just be at a lower angle of attack than the main wing (when in level flight). In a hard pitch up, they are definitely providing lift. Some of the Eurocanards are actually stable aircraft when their canards are allowed to free-stream.
gta4 wrote:
IMHO, I have only seen this during take-off and landing, but I have never seen any canard aircraft use the trailing edge of the main wing to trim in a high-G maneuver. Is it due to the fact that the trailing edge of the main wing are designed for take-off and landing only (about 1G), thus the structure strenth is insufficient for high-G maneuver?

On take-off and landing, they presumably deploy flaps, which means the canards also go to a high angle of attack. I'm not sure how hard a turn would cause the flight control laws to deflect the rear control surfaces as well as the canards.
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