New J-10 thread II

[kickars]

The beams are there to counter the pressure that builds up between the intake and the fuselage, strengthening the intake against the pressure, while at the same time, diffusing the flow outward to relieve the pressure.

Well, I thought words like 'strengthening', 'counter', 'relieve' means 'support'. Anyway, without them the intake won't work as well.

 

[crobato]

The spars are not there to *support* weight. You can see the same on sideways mounted intakes like the JH-7A. It is there to hold the intake against the pressure buildup between the intake lip and the fuselage, which creates an air trap and which creates a strong separating force, and at the same time, route the airflow outside of it.

On a circular intake, the distance between the upper part of the intake and the lower fuselage is greater, so the air does not trap between. Therefore, you don't need spars.

 

[Londo Molari]

So it IS structural support. Without it, air pressure would damage the airframe.

 

[AmiGanguli]

So it IS structural support. Without it, air pressure would damage the airframe.

If the force there were strong enough to damage the plane, then that would imply tremendous aerodynamic resistance. So much that nobody would ever use square intakes close to the body.

They're primarily an aerodynamic feature.

 

[kickars]

Oh well, I fully understand what you mean. But we never said they were there just for supporting the WEIGHT. What I was saying is that they were designed simply for the extra supporting of the intake under pressure. You cannot say if it's under the high pressure, then they don't act as supporting feature. In fact, Crobato used the word 'hold' to describe them.

I guess words like 'aerodynamics' and 'hold' sounds much better than 'support'.

 

[Londo Molari]

If the force there were strong enough to damage the plane, then that would imply tremendous aerodynamic resistance. So much that nobody would ever use square intakes close to the body.

They're primarily an aerodynamic feature.

Of course there is aerodynamic resistance. There is aerodynamic resistance in all planes. Thats why most fighters can't go past Mach 2.5. This doesn't mean that aerodynamic resistance will stop the J-10 from flying. It just means that after prolonged use, the air pressure in that spot will stress and warp the airframe, resulting in permanent damage. It could even rip the plane apart in mid-flight 5 years down the line. So thats why the support beams are necessary.

It can't possibly be an aerodynamic feature. How can vertical bars possibly enhance the aerodynamic performance of the fighter? Aerodynamic features manipulate windflow around them for improved performance and control. These bars just hold the aircraft together. I think the Eurofighter also has similar support structure, but its hidden right in the centre, not visible on the sides. The F-16's airframe seems strong enough not to need it.

 

[AmiGanguli]

It's conceivable that the pressure might damage the plane over time without the bars (although I'm skeptical of that), but the bars don't fix that by providing extra support. They relieve the pressure so that support isn't necessary.

I'm not sure what I can say to convince you, but it just wouldn't make sense to add something that hurt the aerodynamics rather than just reinforcing the intake.

 

[Londo Molari]

It's conceivable that the pressure might damage the plane over time without the bars (although I'm skeptical of that), but the bars don't fix that by providing extra support. They relieve the pressure so that support isn't necessary.

How exactly do vertical bars relieve pressure that builds up between the engine intake and the cockpit?

I admit I'm not an engineer or an expert. But if pressure that builds up in there, I would expect it to force apart the engine intake downwards, and the cockpit upwards, and thats when those vertical bars could hold them in place strongly.

it just wouldn't make sense to add something that hurt the aerodynamics rather than just reinforcing the intake.

Exactly. It doesn't hurts the aerodynamics. Its too small to create significant drag. But it does reinforce the intake.

 

[Infra_Man99]

I think what the guys are saying is that those bars do not hold up the intake. They smooth out air flow to relieve air pressure that builds up in that tight spot to MINIMIZE WEAR AND TEAR on the airframe.

The J-10 could probably do without those bars, because the air intake looks a lot more sturdy than the canards and other jets' horizontal stabilizers. With the bars, the J-10's airframe will LAST LONGER, and this is good for the cut-throat Chinese air force.

 

[crobato]

Actually what the compressed air pressure between the intake lip and the fuselage is to cause the lip to oscillate, or a shaking vibration movement.

This is not something that KANWA implied before that the intake tunnel was too heavy and therefore required additional supports. This mean support against weight, not *hold* against air pressure. These two are very different when it comes to engineering.