Ask anything Thread (Air Force)

Brumby

Major
And I don't understand why you keep posting all these different diagrams first comparing F-15 and F-16 (both of which can release weapons from supersonic speeds) and now of some aircraft wings and some failed weapons releases from external pylons. They don't support your argument at all. What would support your argument is if you found some reliable aerodynamic study that showed a vast increase in the forces sustained from a weapons release from inside a bay than from an external pylon at supersonic speed. That would indicate that there is at least a new challenge that the Chinese had to overcome, (which they in all likelihood did, but at least raises the remote possibility that they didn't). Currently, there is nothing to support even an increase in technical difficulty launching from a bay than from a pylon.
All weapons separation is a challenge especially at supersonic speed because of the complexity of airflow at that speed. It is more so when adding opening of internal bay doors because of the added effect of viscous drag. It is the reason why there are extensive weapon separation testing based on different flight profile, speed and angle of attack to establish safety margin and limitation on release. As an example, during the SDD phase the F-35 conducted 183 weapons separation test and 46 weapons accuracy delivery test. It is a big deal.

One cannot simply assume there is no issue because it is contrary to the science of aerodynamics.
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If it's no big deal, then drop it. If you keep posting diagrams to try to convince people, that kinda says that you think it's a big deal.
The no big deal comment was if there is no evidence that can be provided on the J-20 testing then that is fine and is different from whether weapons separation testing is important or not..
 

ZeEa5KPul

Colonel
Registered Member
There was one (two based on rumors) fitted with WS-10 engines with jagged nozzles in 2018. Haven't seen more of them though.
I consider that good news. I think 2021's engines were part of a backup plan in case there was a problem with the supply of Russian engines. It doesn't make sense to start a new maintenance/logistical stream with an engine not much, if at all, better than the AL-31 when the WS-15 a few years away.
 

Equation

Lieutenant General
All weapons separation is a challenge especially at supersonic speed because of the complexity of airflow at that speed. It is more so when adding opening of internal bay doors because of the added effect of viscous drag. It is the reason why there are extensive weapon separation testing based on different flight profile, speed and angle of attack to establish safety margin and limitation on release. As an example, during the SDD phase the F-35 conducted 183 weapons separation test and 46 weapons accuracy delivery test. It is a big deal.

One cannot simply assume there is no issue because it is contrary to the science of aerodynamics.
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The no big deal comment was if there is no evidence that can be provided on the J-20 testing then that is fine and is different from whether weapons separation testing is important or not..

Nobody said that weapons separation testing is unimportant; we are saying that it is basic to a point that you can assume that it's been tested if it's on a working fighter and one that's in service as well.

What you wrote is just a whole bunch of jargon that, while true, adds nothing to your point. That kind of language can be applied to every aspect of every technology to make it appear that nothing can be assumed without evidence, but the fact is, there is no example of a modern fighter jet that is incapable of supersonic weapons launch. To even suggest that J-20 might be incapable of launching a weapon at supersonic speed just because we haven't seen it is trolling. Basically, you can go on all day and all night about how complex and difficult it is to make a computer even turn on, but even without seeing the demo, I can assure you that Lenovo/Dell/Huawei's next commercial laptop will turn on without issue. You're trying to suggest that that can't be taken for granted.
 

ougoah

Brigadier
Registered Member
How do you think the F-35 program found out that they have ejection issues without actually undergoing a testing regime? It is not a positive or negative thing. I was just asking whether there was evidence of testing. If there isn't any then there isn't any. Not a big deal.

Fair enough. There is no evidence for J-20 being able to launch missiles from internal bay under supersonic speeds. It may be able to do this or it may not. Personal opinion like the other's, it should be able to achieve this feat. Variances in drag caused by changing the geometry and structure of the fighter when the doors are opening and closing should not be a monumentally difficult engineering problem to overcome (but then I've only done basic undergraduate fluids). It would seem reasonable to assume such a capability exists for an organisation and fighter that seemingly has overcome MUCH more difficult aerodynamic problems. Add to this how important it is for a fighter that carries its weapons internally. It is already a given that 4th gens can and often do launch weapons in supersonic flight. Why would PLAAF accept a 5th gen fighter that struggles with the same capability - launching weapons when supersonic.
 

Air Force Brat

Brigadier
Super Moderator
Fair enough. There is no evidence for J-20 being able to launch missiles from internal bay under supersonic speeds. It may be able to do this or it may not. Personal opinion like the other's, it should be able to achieve this feat. Variances in drag caused by changing the geometry and structure of the fighter when the doors are opening and closing should not be a monumentally difficult engineering problem to overcome (but then I've only done basic undergraduate fluids). It would seem reasonable to assume such a capability exists for an organisation and fighter that seemingly has overcome MUCH more difficult aerodynamic problems. Add to this how important it is for a fighter that carries its weapons internally. It is already a given that 4th gens can and often do launch weapons in supersonic flight. Why would PLAAF accept a 5th gen fighter that struggles with the same capability - launching weapons when supersonic.
Good post, Mr. Brumby's only point is that it is a monumentally difficult engineering feat, everything about the J-20 falls into that category. Anytime you raise or lower landing gear you get a massive aorodynamic rumble throught the whole aircraft. All aircraft have relatively low gear opening/closing speeds for just that reason. Mr Brumby's point is that if you didnt get it right? and you don't know that until you cycle those weapons bay doors, load the bays with weapons, and finally launch thise weapons.
 

Air Force Brat

Brigadier
Super Moderator
My belief regarding J-20's ability to launch weapons from its internal weapons bay at supersonic speed is similar to my belief that J-20 has an AESA radar, that J-20 is capable of supersonic speeds in general, that J-20 has demonstrated its ability to fire guided missiles, among others.

I.e.: yes I believe we can assume certain things to be "business as usual" without needing evidence of the kind that you expect or which we would see and receive for weapons projects of other nations who are more open.



There are reasonable capabilities or demonstrations that shouldn't be assumed and which sufficient evidence or rumours should be expected if they are particularly new or exotic or technically challenging. But there are also some capabilities and demonstrations which can be assumed based on how not new, how un-exotic or their relative lack of technical challenge.

Launching weapons from an internal weapons bay while supersonic for a 5th generation stealth fighter should very much in the latter category.

Putting it another way, as localizer said, the most reasonable null hypothesis for your question regarding J-20's ability to launch weapons from its weapons bay while supersonic should be to assume that it can be, and the burden of proof should be on those making the contrary argument instead.
Congratulatios Mr. Blitzo!
 

vesicles

Colonel
Good post, Mr. Brumby's only point is that it is a monumentally difficult engineering feat, everything about the J-20 falls into that category. Anytime you raise or lower landing gear you get a massive aorodynamic rumble throught the whole aircraft. All aircraft have relatively low gear opening/closing speeds for just that reason. Mr Brumby's point is that if you didnt get it right? and you don't know that until you cycle those weapons bay doors, load the bays with weapons, and finally launch thise weapons.

If the J-20 is exceptional in super-sonic maneuvering, as claimed by the test pilot, the designers must’ve focused a lot of their attention on every aspect of the supersonic fighting, which inevitably involves firing the missiles at high speed. It’s difficult and complicated, as you suggested. However, they have solved much harder issues. And launching weapons at supersonic speeds would be something difficult but must be solved. It’s like training for mounted archery. You train your soldiers how to shoot arrows on horseback, but don’t show them how to actually release the arrows on horseback at high speed... it’s hard to train, but not undoable.

To this day, I have not seen any video/photo of the J-20 firing anything. We’ve seen the J-20 flying with their weapons bay doors open, but nothing about actually firing anything. So strictly speaking, we have no evidence for any kind of weapons testing of the J-20. Should we assume the J-20 cannot fire anything and the only thing they can do is to fly low and slow.
 

Air Force Brat

Brigadier
Super Moderator
If the J-20 is exceptional in super-sonic maneuvering, as claimed by the test pilot, the designers must’ve focused a lot of their attention on every aspect of the supersonic fighting, which inevitably involves firing the missiles at high speed. It’s difficult and complicated, as you suggested. However, they have solved much harder issues. And launching weapons at supersonic speeds would be something difficult but must be solved. It’s like training for mounted archery. You train your soldiers how to shoot arrows on horseback, but don’t show them how to actually release the arrows on horseback at high speed... it’s hard to train, but not undoable.

To this day, I have not seen any video/photo of the J-20 firing anything. We’ve seen the J-20 flying with their weapons bay doors open, but nothing about actually firing anything. So strictly speaking, we have no evidence for any kind of weapons testing of the J-20. Should we assume the J-20 cannot fire anything and the only thing they can do is to fly low and slow.[/QUOTE / I'm with you at every step, but all these engineering exercises are all new, as I will continue to remind the J-20 is indeed a "clean sheet" Chinese aircraft. I can also assure you that nothing has been assumed to be a done deal? or even easy by the Chinese engineers? So Mr Brumby's questions are fair, just as people question every aspect of JSF? Now, that we see the J-20 flying with a developmental test squadron, its likely that many of these issues have been addressed and are behind us?
 

vesicles

Colonel

I agree with you as well. With a new design like the J-20, nothing is granted.

However, what I disagreed with him was his rationale for doubting the weapons launching system in the J-20. “Because we haven’t seen the J-20 launching a missile at high speed?” Even we get a video of the J-20 launching a weapon, or opening the weapons bay door, in flight, how do we verify that the weapon was actually launched at supersonic speed? It would be impossible for us the amateurs to provide irrefutable evidence. And we know that the PLA won’t bother to provide any irrefutable evidence. And in the end, some people will choose not to believe it, just like 20% of Americans still don’t believe the 1969 moon landing actually happened. what can you do?
 
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