We should indeed be critical about such statements. Not that the sustained turn rate of the F-16 is anything to write home about.
Aerodynamics thread
- Thread starter siegecrossbow
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We should indeed be critical about such statements. Not that the sustained turn rate of the F-16 is anything to write home about.
So are you saying the F-16 wasn’t designed for dogfighting? Got it. The F-16 is a trash dogfighter which is why no one uses it for that role. Makes sense.
A J-20 with the sustained turn rates of a vintage F-16 (not the overloaded later blocks) would not make it a good "dogfighter" at subsonic speeds, which I think would be rather disturbing to see in the first place.
1) So what, in your words, is the F-16 designed for then? From what energy diagrams I’ve been able to find, the F-16 has better STRs than the F-15, and edges out the Su-27, in the subsonic range. The Su-27 should have better ITR, and the F-15 leans on a climbing advantage to recover energy, and both match and then take over in energy advantage at higher altitudes (above 10,000 ft) and speeds.
2) The J-20 was also described as having superb transsonic and unparalleled supersonic maneuverability. Dogfighting, as I’ve had to belabor many times before, isn’t an exclusively subsonic affair. It’s not even exclusively about STR.
3) My broader point seems to have been missed here. Whether the J-20 has the best STR or not that in its worst performing regime it’s still being compared to a fighter that was designed to have good A2A combat performance is quite suggestive of what roles it was designed for, and what its performance capabilities are.
Pilot testimonies have also stated that it is the most maneuverable aircraft in the PLAAF, so we have more to go on than just an unspecified block F-16.
The J-20 does not have a weapons bay size optimized for strike, or a high powered anti armor cannon. The only merit where it wins in strike role is it’s stealthiness, but that is only because PLAAF doesn’t have any other stealth manned aircraft.
The J-20’s design is clearly heavily geared towards air to air. Most interceptors are excellent air superiority fighters (like the spitfire), but not all air superiority fighters can conduct interception well. Interceptors often operate at heavy numerical disadvantage over hostile airspace, being pitted against the most dangerous and well defended enemy air targets. To complete this mission, a fighter needs to be able to get inside safely, “win” the duel and get out safely as well.
Among all fighters in the PLAAF, I would say the J-20 is by far most suited to that mission.
The J-20 does not have a weapons bay size optimized for strike, or a high powered anti armor cannon. The only merit where it wins in strike role is it’s stealthiness, but that is only because PLAAF doesn’t have any other stealth manned aircraft.
The J-20’s design is clearly heavily geared towards air to air. Most interceptors are excellent air superiority fighters (like the spitfire), but not all air superiority fighters can conduct interception well. Interceptors often operate at heavy numerical disadvantage over hostile airspace, being pitted against the most dangerous and well defended enemy air targets. To complete this mission, a fighter needs to be able to get inside safely, “win” the duel and get out safely as well.
Among all fighters in the PLAAF, I would say the J-20 is by far most suited to that mission.
The lack of empircal data always leads to pi**ing contests. Also using a comparison with a 50s years old aircraft which was exceeded in sustained turn rate department often and a long time ago is not some proof for anything.
Some basics, from what I’ve gathered over the years, about dogfighting that I think are probably necessary to keep in mind if we ever hope to have constructive conversations about fighter designs.
STR is most important for defensive maneuvers and gun-fighting. The defensive aspect comes from needing to make tight sustained turns outside the maneuver envelope of an incoming missile. The missile may have much higher maneuverability but a combination of the missile’s need to close a distance to hit its target and its much more limited burn time means there are potential windows of escape, depending on the conditions the missile was launched in relative position of each fighter. The tighter and faster your sustained turn the better your chances of exploiting that window of escape. STR matters for gun fighting because it’s not enough to get a position in a gun fight. That position must be held long enough to ensure a kill.
Good energy management and recovery, which feeds into STR but includes many more attributes, is similarly important for preserving defensive maneuvers and for prolonged engagements. If an engagement goes beyond an initial exchange at the merge the fighter that has, and is able to preserve, the most energy has a maneuver advantage. Similarly, if you are trying to escape a locked missile your odds are better, and your maneuver advantage can be better maintained, if you have higher initial speed, better acceleration, or faster climb.
ITR and nose pointing is mainly needed for getting into a kill position in a missile fight. The trade-off is that these kinds of maneuvers can often bleed energy really quickly. This is where good energy recovery can trump good energy preservation, as recovering energy can allow a fighter to expend its energy in an expensive maneuver and then try again if it has failed, or needs to attack multiple adversaries.
Energy advantages are mainly acquired through a combination of speed and altitude. They’re essentially about maximizing the potential energy of your kinematics. Energy preservation is attained by minimizing drag during maneuvers, and in a relative sense from either starting at a higher initial speed or higher altitude than your adversary. Energy recovering is mainly attained through climbing and acceleration. However, for a fighter it’s not enough to be able to preserve and recover energy. Attaining higher PE is mostly useless if you aren’t able to also maneuver well in those higher energy states. This is why a Mig-28, despite having a raw energy advantage, is practically useless against the F-15 past the initial point of intercept. It’s also why transsonic and supersonic maneuverability, as well as high altitude maneuverability, are advantages that have received so much emphasis with newer fighter designs.
There is no such thing as a fighter that excels at all of the above relative to other fighters. All designs make compromises and trade-offs on some of these parameters in order to excel at others. The rest is left to tactics, sensors, and the capability of the kill vehicle. That’s why it’s really dumb and simplistic to try to assert, in broadbased generic terms, the superiority of one fighter design over another. At best what we can say is that fighters that can maintain and recover greater kinematic energy should have advantages over fighters that can’t, but even that isn’t always so cut and dry in practice. The specific flight envelope fighters find themselves in at a point of encounter can drastically alter the balance of advantages and disadvantages each design might have.
STR is most important for defensive maneuvers and gun-fighting. The defensive aspect comes from needing to make tight sustained turns outside the maneuver envelope of an incoming missile. The missile may have much higher maneuverability but a combination of the missile’s need to close a distance to hit its target and its much more limited burn time means there are potential windows of escape, depending on the conditions the missile was launched in relative position of each fighter. The tighter and faster your sustained turn the better your chances of exploiting that window of escape. STR matters for gun fighting because it’s not enough to get a position in a gun fight. That position must be held long enough to ensure a kill.
Good energy management and recovery, which feeds into STR but includes many more attributes, is similarly important for preserving defensive maneuvers and for prolonged engagements. If an engagement goes beyond an initial exchange at the merge the fighter that has, and is able to preserve, the most energy has a maneuver advantage. Similarly, if you are trying to escape a locked missile your odds are better, and your maneuver advantage can be better maintained, if you have higher initial speed, better acceleration, or faster climb.
ITR and nose pointing is mainly needed for getting into a kill position in a missile fight. The trade-off is that these kinds of maneuvers can often bleed energy really quickly. This is where good energy recovery can trump good energy preservation, as recovering energy can allow a fighter to expend its energy in an expensive maneuver and then try again if it has failed, or needs to attack multiple adversaries.
Energy advantages are mainly acquired through a combination of speed and altitude. They’re essentially about maximizing the potential energy of your kinematics. Energy preservation is attained by minimizing drag during maneuvers, and in a relative sense from either starting at a higher initial speed or higher altitude than your adversary. Energy recovering is mainly attained through climbing and acceleration. However, for a fighter it’s not enough to be able to preserve and recover energy. Attaining higher PE is mostly useless if you aren’t able to also maneuver well in those higher energy states. This is why a Mig-28, despite having a raw energy advantage, is practically useless against the F-15 past the initial point of intercept. It’s also why transsonic and supersonic maneuverability, as well as high altitude maneuverability, are advantages that have received so much emphasis with newer fighter designs.
There is no such thing as a fighter that excels at all of the above relative to other fighters. All designs make compromises and trade-offs on some of these parameters in order to excel at others. The rest is left to tactics, sensors, and the capability of the kill vehicle. That’s why it’s really dumb and simplistic to try to assert, in broadbased generic terms, the superiority of one fighter design over another. At best what we can say is that fighters that can maintain and recover greater kinematic energy should have advantages over fighters that can’t, but even that isn’t always so cut and dry in practice. The specific flight envelope fighters find themselves in at a point of encounter can drastically alter the balance of advantages and disadvantages each design might have.
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Where’s your empirical data that the F-16 was exceeded in STRs in the subsonic regime often and a long time ago? Or is this from the same sorts of anecdotal hearsay you just poo-pooed a few posts back?
Forgot to add that it can also be the case that a fighter that has a recovery advantage can still find itself vulnerable to a fighter that emphasizes better energy preservation while it is in the process of trying to recover energy. As I mentioned in my conclusion, these different advantages can be highly situational.
Also worth noting here that as the above pertains to the J-20 interceptor thesis, if the J-20 is indeed meant to perform an interceptor role with high speed at the merge, *but* also has good (perhaps even excellent or "unparalleled") supersonic maneuverability, then that effectively means the J-20 would be used in combat scenarios where it not only is supposed to start with an energy advantage *but* be able to convert that energy advantage into a maneuver advantage, *which* would effectively mean that it is not designed to be the same kind of traditional "interceptors" we tend to think of like the Mig-28 or Mig-31. In fact, this sort of engagement profile would line up quite cleanly with testimonies we've heard about how the F-22 has been utilized in dogfighting exercises, and that in turn would be suggestive against the notion that the J-20's design is geared towards the kind of "pure" interceptor role that it's often been assigned.
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Here Mr. Brumby, I'm going to agree with Blitzo, Dr. Song's excellent design paper, citing the F-22 as the platform he was aiming at when designing the J-20, (read Siege's excellent translation of Dr. Song's paper).... the J-20 went with distant coupled canards to increase "pitch rate" as OVT was likely to be unavailable, and the ventral fins to assist the J-20 with post stall maneuverability and recovery...
J-20 Designer Yang Wei, Dr. Song's protégé, went with all of those elements to aerodynamically allow the J-20 to achieve "super maneuverability" in the absence of OVT, and the end product is the beautiful J-20.....
I could cite the "roll-over breakout" at Zhuhai on the last day of the show as visual proof, of the J-20's excellent roll rate and "departure resistance".. seeing this we could probably agree that Dr. Song was able to see his vision largely achieved...