Russia's next wing

From my post at the **** forums:

Given the saying from one of the head designers that when the Mig-29 and Sukhoi-27 were designed, they first chose the “perfect” wing and then designed the plane around it:

I can’t help but to ask the question, what wing will the PAK-FA have?

A forward swept design has already been ruled out (despite its favorable shifting forward of verticle cross-section). The high speed delta of project 1.44 also seems unlikely.
Both swept wings similar to the Su-27 and Mig-29 as well as unswept and JSF and F-22 style wings have been suggested.

But, first I want to bring up the unusual wing found in the subsonic “project integral” which has borne fruit in the Shafagh trainer/strike fighter of Iran.

I don’t know much fluid dynamics but most of the following observations are relatively obvious. Still, I want to apologise for the poor presentation:

-First look at the design from above. Estimate the center of gravity and center of lift.
Note the ratio of the percentage of vertical cross-section in front of and behind these two points. Now visualise the Su-27 and its distribution.
In comparision, project Integral is virtually symmetric.

-Now look at project intergral from the front. Imagine you are the oncoming airstream. Put a line through the center of gravity, so that it runs straight through both wings and rotate the aircraft (pitchwise) slowly along this line.

-As the angle of attack increases, drag increases almost perfectly symmetrically with the build-up happening first toward the center of the aircraft and then toward the outer wing.

-Note that the drag also has a tendency to build up near the center of gravity, -not only laterally but longitudinally as well.

-Also notice that the area to first encounter air-flow separation and also the area hit by the highest level of drag is near the center where it can easily be controlled (or even used) through elevator and aileron movements. (If the drag built up near the outer wing tips like on the flanker it could damage the ability to roll and pitch)

-Futhermore as the ellipse expands it does so in a very regular way, with the angle of sweep of the leading edge increasing at a very regular rate as you move toward the outside of the inner wing. The increasing angle of sweep would rapidly accelerate the airflow as it moved toward the outer section of the inner wing. This might also have something to do with preventing airflow separation and distributing suction and the flow of air as it runs along the outside edge of the wing. I don’t know. Who knows?

In short gentlemen (and women): I am proposing that the wing of the Shafagh/Integral was originally designed for sustained high angle of attack maneuvering.

A similar almost perfectly symmetric fore-aft distribution of vertical cross section (though distributed in a triplane configuration) can be found on the S-37a Berkut.

Experiments I conducted using x-plane 5.54 showed favorable improvements in controllability in a variety of situations but are far from conclusive (due to software limitations).

Two more notes (wildly speculating for fun here):

Could the shafagh be used as a light fighter, lifting a strong enough radar and 2-4 R-77s?
A similar design could certainly be one of the most maneuverable and stealthy aircraft out of the early 90s light CIS designs.

Also what is the possibility of the replacement for the Mig-31 and the Su-24/34 being the same aircraft? The T-60 was designed to a Mach 2.4+ standard and the T-4MS aimed for M3.5!
The next airplane would certainly have the range/payload ration for an interceptor and manueverability would not be important.

So what do you all think?
-Avimimus”

Overscan responded with this useful information:

“Your analysis of the Integral wing is basically correct.

From an article on Vityaz-2000:
Quote:

The most important thing about the aircraft is that the ‘integral’
configuration provides high aerodynamic performance at low as well as high
angles of attack due to the aircraft optimal planform, and specially
developed flight structure with reciprocal-type components: wing panels,
‘disk’ centerwing section, wing extensions and their fuselage parts. The
wing extensions and disk turbulent flow systems provide smooth, without
rapid changes, association of the lift and longitudinal coefficients
according to the angle of attack to compensate for wing panel stalling. The
more the angle of attack, the more the centre-wing section works, which,
supported by swivel leading edge flaps, increases the angle of attack and
smoothes the decreasing of the lift coefficient up to 50-60 degrees. “