Comparsion of Tilt angle tails with straight angle

[Rank]

West fighters like F22, F16, F18, Rafale, Euro etc having tilt angle tails. What are the advantages of tilt angle tail and straight angle tails ?

 

[maxpayne]

Something come to my mind, but not good for this forum. Ahem Ahem!

 

[Rain]

Aerodynamics: any expert here?

 

[SQ8]

Tilted how?

The tails of fighters such as the F-22, F-35 and the F-15SE were tilted precisely for RCS measures. as the angled surface tends to bounce a lesser amount of energy return as compared to a straight surface.

@gambit can explain better.

If you are referring to tails "tilted" with regards to their shape (if viewed from side).. these are due to aerodynamics. There could be many aerodynamic reason behind this and is usually related to the shape of the airframe and flight requirements.

 

[Rank]

So why chinese Fighters having straight tails ?

 

[gambit]

West fighters like F22, F16, F18, Rafale, Euro etc having tilt angle tails. What are the advantages of tilt angle tail and straight angle tails ?

If you are referring to shape, it does matter. For the third (last) shape, it is the worst in terms of contributing to final RCS.

Any structure is a finite body, meaning it has edges. Nothing is infinite. For the flight controls structures, ie the larger wings and smaller stabilators like your examples, if the impinging radar signal is at the leading edge, there will be surface waves traveling (left to right) the entire expanse of the structure, for example. At the trailing edge, those surface waves will radiate into free space and here is where the angle of the trailing edge matter.

In the above illustration, the arrow representing the incoming radar signal hits the leading edge and some of its energy will produce what is called the 'Keller Cone'. The rest of the radar signal will become surface waves. Keller Cone signals will radiate into free space and this is why 'stealth' design demand angling the leading edge to deny the seeking radar as much of the Keller Cone radiation as possible. A straight wing will return the highest energy. We do not want that. A leading edge sweep will reduce that amount and facilitate higher speed as well. But if we ignore the radiation pattern at the trailing edge, we defeat the purpose of 'stealth' in the first place.

It gets more complex but the basic understanding is this: Finite structures inevitably radiate and it is important to control as much as possible those radiation patterns.