JF-17 Thunder Multirole Fighter [Thread 4]

[Safriz]

You should really walk up close to an airplane and actually touch it to see what I mean.

On the fuselage, the wrinkles lessen as the pressure difference at altitude increases. On a wing, the top surfaces flexes while the bottom one stretches due to wing flexibility.

Sorry i never seen a plane flying with wings as wrinkled as a 90 year old granny.
Its basic aerodynamics that airflow has to remain smooth and uninterrupted around the wings..
With so many bumps its impossible to remain airborne...

 

[gambit]

You lot are all educated people.
How can you even assume that a plane with so much deformed 'lift providing surfaces' can remain airborne?
The examples of ripples in the plane others have pisted is on fuselage and other 'non lift generating' surfaces.
Dont you think that so much heavy deformation will cause turbulance under the wing and the plane will fall off the sky?

Lift comes from the wings, not the fuselage. If there are any surface irregularities on the wings due to age and manufacturing deficiencies, as long as they are nothing like ice formations formed in cold weather, lift will be available.

Do an image search on 'wing ice formation' and see some really horrific pictures...Like this...

Santa Ynez Valley Journal | PLANE TALK

How does ice cause a plane to crash?: Scientific American

Ice typically builds up when tiny cloud droplets impact and freeze on the leading edges, or front surfaces, of the plane. The ice alters airflow over the wing and tail, reducing the lift force that keeps the plane in the air, and potentially causing aerodynamic stall—a condition that can lead to a temporary loss of control.

It is the leading edge of an airfoil that create the necessary first conditions for lift.

 

[Safriz]

Do you really think these are ripples in the metal,not vapors snd light playing tricks?
Do you think a planes with so much deformed wings can fly?

 

[VCheng]

Sorry i never seen a plane flying with wings as wrinkled as a 90 year old granny.
Its basic aerodynamics that airflow has to remain smooth and uninterrupted around the wings..
With so many bumps its impossible to remain airborne...

You would be surprised then, for sure.

Do you really think these are ripples in the metal,not vapors snd light playing tricks?
Do you think a planes with so much deformed wings can fly?

That is not a significant deformation, merely small surfaces ripples that do NOT affect the lift in any meaningful way. Quite normal, actually.

 

[Safriz]

You would be surprised then, for sure.



That is not a significant deformation, merely small surfaces ripples that do NOT affect the lift in any meaningful way. Quite normal, actually.

If its normal then there must be other examples of planes flying with same or similarly deformed wings.
This cant be unique to JF-17.
Can you or anybody else post another similar example?

 

[VCheng]

If its normal then there must be other examples of planes flying with same or similarly deformed wings.
This cant be unique to JF-17.
Can you or anybody else post another similar example?

Wing flex is a very different thing. These are just small surface ripples, and you are correct, they are not unique to the JF-17. Other planes have them too.

 

[Armstrong]

Are you guys still talking about those goddamn ripples ?

 

[Safriz]

Are you guys still talking about those goddamn ripples ?

We like technical discussions? Dont we?

 

[VCheng]

We like technical discussions? Dont we?

No, we only say we like technical discussion, but what we really mean is that we like only those aspects that convince ourselves just how wonderful we are, nothing too critical, mind you!

The path ahead is possible only by falling into the company sanctioned line, led by those holding the leash.

 

[Safriz]

No, we only say we like technical discussion, but what we really mean is that we like only those aspects that convince ourselves just how wonderful we are, nothing too critical, mind you!

The path ahead is possible only by falling into the company sanctioned line, led by those holding the leash.

There is no such thing as 'nonbiased'. Everybody is biased one way or another.
Plus some criticisms may be valid,but most are on the lines of'
"If its not from the west,there must be something terribly wrong with it,but if it is from the west,nothing can go wrong with it ever".

 

[Safriz]

@ On topic,about the Picture,to me vapors can be seen on top of the plane and making the edges white,and look like the most probable cause of the rippl effect.

To you and many others its the metal itself buckling under stress.

For that i asked for another picture of another aircraft showing ripp'es on the wing...none was presented.
I win

 

[VCheng]

@ On topic,about the Picture,to me vapors can be seen on top of the plane and making the edges white,and look like the most probable cause of the rippl effect.

To you and many others its the metal itself buckling under stress.

For that i asked for another picture of another aircraft showing ripp'es on the wing...none was presented.
I win

You win? Congratulations.

I am content just being correct:

A-340 wing:

It is not a new problem:

If anybody is interested, please do read this paper:

C.B. York, F.W. Williams: "Aircraft wing panel buckling analysis: efficiency by approximations." Computers & Structures, Volume 68, Issue 6, September 1998, Pages 665–676.

Fig. 8. A comparison of buckling modes for (a) rigorous and (b) approximate infinite width analyses of the composite blade-stiffened panel subject to load case 1 of Table 4(c), for selected skew angles α°. Wavelength parameter (&#958 or (ξ, g) and load factor (F) are given below each of the modes, which are shown over length 2 and width B.

 

[SQ8]

these Vegetarians .....

the phenomenon is called REFRACTION !

LERX tends to cause circular vapor trails, which causes light to bend.
The progressive dark and light shades you see on the LERX, which a vegetarian is associating to metal fatigue, or ill engineered metal is only the subsequent rings.

If you had the lateral view of the plane in the same situation, you will not see the bent metal. you will see ciruclar trails of vapor.

Let's see:

Refraction is the change in direction of a wave due to a change in its medium, whereas diffraction can be constructive and destructive to create light and dark areas in the manner that you describe. BOTH do not apply here.

Those are actual ripples in the fuselage skin, and no big deal.

Comments on the same phenomenon by an engineer who was part of the F-16 design team(just in case there are still doubters)

The ripples appear to be the result of thin sheet metal construction of the LERX. That area would have a high air pressure during a pull up. A better construction (but more expensive) would be a thicker skin or a honeycomb skin. The thin metal may have enough strength to hold the load, but it really looks bad

 

[VCheng]

Comments on the same phenomenon by an engineer who was part of the F-16 design team(just in case there are still doubters)

I am no F-16 design engineer, but I do know at least a few things.

 

[SQ8]

I am no F-16 design engineer, but I do know at least a few things.

I just felt that with the imaginative theories going around it was better to get thing cleared up.

FYI that answer was given after showing the picture of the JF-17 with the ripples.. so it be more exact than that