J-20... The New Generation Fighter III

Originally Posted by T-U-P

I got a question:
What's the advantage of using drag chutes for landing as opposed to something similar to a spoiler? In war times wouldn't having a drag chute slow down the sortie rate? since every plane that landed would need to have a new drag chute installed. Also, someone needs to get rid of the used drag chute off the runway right?

The drag chute is far more effective simply because it has a larger surface area, and yes someone does have to remove them from the ops area, I imagine, the chutes are packed and ready to go. Their use as noted by some posters is cultural, the Chinese and Russians continuing to use them, and they are very cool, in fact my formative memories of fighters is seeing them pop the chute on roll out, and then watching the chutes collapse, as they were released from the aircraft. F-15s, J-20s, F-18s have fuselage mounted speed brakes which are also quite effective and may be deployed in flight, spoilers the same, where they actually help you slow approach speed, obviously a far more usefull tool all around. Both have their purpose, and it is probly nice to have both.

Originally Posted by plawolf

Well I think the biggest advantage is that a drag chute will stop a fighter in a considerably shorter time/distance compared to using airbrakes.

Drag chutes are pre-packed and just inserted into the housing and fastened, so it seems a relatively straight forward and quick procedure, so I really cannot see that slowing down sortie rates by the slightest.

Since the drag chutes are manually released by the pilot, they can pick a spot/area on the runway to release them where a crew is waiting to collect them, whatever system they have already for collecting used chutes should also work in war time conditions, as even in peace time, you really want to get hold of the chutes asap after they detach for nothing more than practical reasons, as you don't want to be chasing them all over the airfield if it's winding, and the longer you let them drift about, the greater the chance they would snag something and tear.

Sorry wolfie, I didn't see your post, we got to the same point, and you made it much better than I.

Originally Posted by kyanges

Thanks, I found it. Seems like it's simply repeating one of the views that the J-20 is a strike, and the J-31 is now the air-superiority fighter.

I wish China would just release the physical dimensions of the J-20...

It really probably has more to do with simple physics, engineer and I had this same discussion, Editor Tirpak can likely tell you exactly how long the J-20 is. It has more to do with mass centralization, the J-20 is longer and therefore it will take longer to make pitch transitions all other things being equal, than the F-60 which is more mass centralized. The primary advantage of TVC is quicker pitch response, which will increase turn rate, the only reason it is included on the F-22, and not the J-35. I am NOT trying to relight the dead horse beaters, simply saying that tactically the F-60 also has a niche, and that there are obviously two separate design philosophies at work here. The editors thoughts mirror my own, and that of many in the aviation community.

And NO, I am NOT labeling the J-20 a strike aircraft as the F-35, I don't believe that nonsense, nor should you.

The Su-27 being a more maneuverable aircraft than the MiG-21 is also a lot bigger, yet you don't call the Su-27 a striker. Size has little correlation with maneuverability. Those authors just say what they want to believe.

Originally Posted by Air Force Brat

It really probably has more to do with simple physics, engineer and I had this same discussion, Editor Tirpak can likely tell you exactly how long the J-20 is. It has more to do with mass centralization, the J-20 is longer and therefore it will take longer to make pitch transitions all other things being equal, than the F-60 which is more mass centralized. The primary advantage of TVC is quicker pitch response, which will increase turn rate, the only reason it is included on the F-22, and not the J-35. I am NOT trying to relight the dead horse beaters, simply saying that tactically the F-60 also has a niche, and that there are obviously two separate design philosophies at work here. The editors thoughts mirror my own, and that of many in the aviation community.

And NO, I am NOT labeling the J-20 a strike aircraft as the F-35, I don't believe that nonsense, nor should you.

It's also a fact the longer moment of arm of the canards of the J-20 balances out the increase in inertia (Remember here that the comparatively longer J-20 is also thinner so its mass stays about the same and the increase in moment of inertia is due mainly to increase in length). Of course other factors also have to be taken into account, like air resistance and the fact that the J-20 can also use its ruddervators for pitch control and this in combination with the canards can increase the pitch force. In any case, the pitch rate and roll rate of an aircraft has no direct relation to its turn rate, something which I think some of the members here, who I believe has studied aerodynamics (delft, engineer, i.e.), will agree with me.

I have been bothered by the drag chute from day one. Not only the mechanism adds dead weight to the aircraft, it already has a dedicated air brake, also both the canards and tail can be actuated to act as air brakes.

Originally Posted by Engineer

The Su-27 being a more maneuverable aircraft than the MiG-21 is also a lot bigger, yet you don't call the Su-27 a striker. Size has little correlation with maneuverability. Those authors just say what they want to believe.

While we are on the subject of size, a comparison between the J-20 and the J-15 based on satellite images indicated that the J-20 was at least a meter shorter than the J-15, which is slightly over 21 meters.

Originally Posted by Engineer

The Su-27 being a more maneuverable aircraft than the MiG-21 is also a lot bigger, yet you don't call the Su-27 a striker. Size has little correlation with maneuverability. Those authors just say what they want to believe.

While we are on the subject of size, a comparison between the J-20 and the J-15 based on satellite images indicated that the J-20 was at least a meter shorter than the J-15, which is slightly over 21 meters.

Originally Posted by siegecrossbow

While we are on the subject of size, a comparison between the J-20 and the J-15 based on satellite images indicated that the J-20 was at least a meter shorter than the J-15, which is slightly over 21 meters.

I thought we were done with the subject of size :P. The best methods we've employed all come down to a length of 19.5-20.5 meters. Everyone else can dispute that if they want, but no one has offered a better set of measurements. Some have gone to silly extents to try to prove the J-20 is a behemoth like using canopy or wheel base comparisons.

18 meters for life.

Originally Posted by hmmwv

I have been bothered by the drag chute from day one. Not only the mechanism adds dead weight to the aircraft, it already has a dedicated air brake, also both the canards and tail can be actuated to act as air brakes.

As I stated earlier, the drag chute has more surface area, hence it provides a lot of bang for the buck. It also save on tires and brakes, and moves the load factor back to the relatively robust rear fuselage, and gets it off of gear legs and wings that support them. That it is archaic, isn't a problem for the pilot or the engineer, also a chute and packing aren't that heavy, they don't have to be designed to take repeated stresses, they are cheap, and they only have to work once.

Originally Posted by latenlazy

I thought we were done with the subject of size :P. The best methods we've employed all come down to a length of 19.5-20.5 meters. Everyone else can dispute that if they want, but no one has offered a better set of measurements. Some have gone to silly extents to try to prove the J-20 is a behemoth like using canopy or wheel base comparisons.

I didn't mention size, I just asked what people thought of editor Tirpaks observations about the role of the F-60, as an A2A aircraft with possible Naval applications, as opposed to his comments about the J-20, I know what the J-20s proposed role is, having read Dr. Songs excellent paper. As the editor of Air Force Magazine, editor Tirpak is well studied in all aspects of not only design, but functionality. I honestly have to state that he has more credibility than most posters, who often allow their loyalties and emotions to make some absurd commentary, that ignore the laws of physics and in particular the laws of aerodynamics, I was hoping for some acknowledgement that he may be onto something, affirming many of my own observations?

Originally Posted by Quickie

It's also a fact the longer moment of arm of the canards of the J-20 balances out the increase in inertia (Remember here that the comparatively longer J-20 is also thinner so its mass stays about the same and the increase in moment of inertia is due mainly to increase in length). Of course other factors also have to be taken into account, like air resistance and the fact that the J-20 can also use its ruddervators for pitch control and this in combination with the canards can increase the pitch force. In any case, the pitch rate and roll rate of an aircraft has no direct relation to its turn rate, something which I think some of the members here, who I believe has studied aerodynamics (delft, engineer, i.e.), will agree with me.

As a matter of fact there are horribly complex connections between all the degrees of freedom of an aircraft and they became very troublesome in the 1930's when aircraft got flaps, retractable undercarriages &c. and got faster ( think DC-3, Spitfire ). You want to make the aircraft easily controllable at ever speed and in every configuration. That soon needed power assisted controls and by now need very sophisticated computer control between the pilot and the control surfaces.

When an aircraft has larger control surfaces does that not help it manuver better, so by the J20 being large it is more manuverable and has a higher max TO weight limit which means it can carry more or larger weopons