J-20... The New Generation Fighter II


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MiG-29

Banned Idiot
No one is arguing that drag is based on volume. Stop with such stupid strawman arguments.

Drag is also dependent on drag coefficient, not just wing area as you have attmpted to portrait.
drag is dependant upon speed, air density, viscosity, compressability inclination and area, and if you want the proof




 

Engineer

Major
drag is dependant upon speed, air density, viscosity, compressability inclination and area, and if you want the proof
It also depends on drag coefficient, which you are still trying to dismiss. From your own diagram:
Coefficient Cd contains all the complex dependencies and is usually determined experimentally.
This shows that your method of estimating drag by eyeballing is fundamentally flawed, thus you have no knowledge on the drag of the J-20 or the F-22 to conclude anything.
 

siegecrossbow

Brigadier
Staff member
Super Moderator
Hey guys CJDBY is following our thread! Too bad the server is down right now. I'll post a link when it is back up again.
 

Bltizo

Lieutenant General
Staff member
Super Moderator
Hey guys CJDBY is following our thread! Too bad the server is down right now. I'll post a link when it is back up again.
"We scratch your back..." ;)

Also siege, as mod now are you able to close threads and move posts and the like? I think this one has already gotten a bit high despite only being opened a few months ago. The less pages there are the easier it is for people to reference back to specific posts.
 

MiG-29

Banned Idiot
It also depends on drag coefficient, which you are still trying to dismiss. From your own diagram:


This shows that your method of estimating drag by eyeballing is fundamentally flawed, thus you have no knowledge on the drag of the J-20 or the F-22 to conclude anything.
The drag coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag. This equation is simply a rearrangement of the drag equation where we solve for the drag coefficient in terms of the other variables. The drag coefficient Cd is equal to the drag D divided by the quantity: density r times half the velocity V squared times the reference area A. Cd = D / (A * .5 * r * V^2)

The quantity one half the density times the velocity squared is called the dynamic pressure q. So

Cd = D / (q * A)

The drag coefficient then expresses the ratio of the drag force to the force produced by
 

Engineer

Major
You know what is a test prior to fly? they why is not using the canards differentially at roll at flight?
Do you know the purpose for differential canards? It's to enable roll control, and also limited yaw control. Why don't you see them used differentially? Canards deflection are very small and still gives the aircraft enormous agility.
 

Engineer

Major
The drag coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag.
Hence you can't calculate drag just by eyeballing. You need windtunnel data, or your statement regarding J-20 having higher drag is false. Nothing more needs to be said.
 

johnqh

Junior Member
Hence you can't calculate drag just by eyeballing. You need windtunnel data, or your statement regarding J-20 having higher drag is false. Nothing more needs to be said.
You missed Mig-29's point.

He is saying z = f1(x, y). (z is the drag, x is the wing area, y is the drag coefficient)

You are saying "but you don't know y".

He is saying "But y = f2(z, x)".

ROFL

You cannot win
 
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