- 4 October 2006
- Reaction score
What happened to the S-37's FSW? ???
frank said:But what did happen to the S-37s wing? I missed something.
Sundog said:The other problem with forward swept wings is even with advanced aero-structures, you're still limited to M=1.7 . Any speed above that and a standard wing with rearward sweep is better since the FSW would still be weight prohibitive above that speed to counter-act the wing's natural pitching moment/twist.
I don't know if there is any evidence to support it, but my understanding is Grumman's ATF proposal had a forward swept wing and it also was placed last in the initial competition. I know there is the painting of the Grumman FSW with the large canard, but I don't know if that was actually their submission.
Rough translation of the Airwar.ru pageS -32 (Su-27KM) carrier-based fighter
Preliminary operations on creation of the heavy fighter of the fifth generation for VVS and PVO began at the end 1979 within the framework of program I -90 (“the fighter 1990- X of years”). In 1981 g. the special-purpose comprehensive program of the creation of fighters 90 X yr. was affirmed by the decision of government. Works on the creation of multipurpose tactical fighter headed MMZ Mikoyan. On the recollections the O. S. Samojlovich, Silaev (minister OF [MAP] - [prim].SB) insisted so that Sukhoi KB would participate in this work on the competition with KB Mikoyan. However, E. Ivanov decisively was rejected, after saying that Su-27 - this is a fighter 90 X of years. The potential possibilities of aircraft are such, that to the end of century will not be created not one machines, which could exceed Su-27 and its modifications.” OKB [im]. OF P.O. Sukhoi was charged the development of attack aircraft for the program Sh -90 (“the attack aircraft 1990- X of years”). Nevertheless, when in 1983 OF OKB Simonov headed M. p., he makes decision about the initiative-taking development of the fighter of new generation. The designation of project - S-22, similar to index of one of the modifications of fighter-bomber Su-17, made it possible to conduct works without the premature publicity. Simonov was the large enthusiast of aeroplane design with the sweptforward wing, and he decides to use it on the new fighter. The major advantages of this layout are: a notable increase in the lift-drag ratio during the maneuvering, especially with the low speeds; large lift in comparison with the sweptback wing, which has identical area, and, therefore, also large load capacity (to 30%); a increase in the flying range in the subsonic modes due to the smaller trim drag: the best controllability at the low subsonic velocities (and, as a result, improvement [VPKH]); a improvement in the conditions for work of wing mechanisation (which also reduces takeoff and landing distances); smaller stalling speed; the improved antispin characteristics; a increase in the internal volumes of glider, especially in the sites of the joint of wing and fuselage, which provides the best conditions for the formation of internal loading compartments. there was in this diagram significant shortcomings. The attempts to use it undertook even in the middle 40- X yr. - Ju-287 (Germany), [LL]- E p. v. Tsybin. Elastic positive wing divergence was principal restriction (twisting and the subsequent destruction of wing). The wings from the aluminium and even steel alloys air-blast in the supersonic wind tunnels were destroyed. Attempts at the increase in the rigidity of the wing, which has traditional metal construction, led to the inadmissible increase of mass. The use of composite materials made it possible to fight with the twisting with the aid of the specially oriented coil of [uglevolokna]. By this was assigned the special arrangement of the flexural axes of wing (by the directed twisting strain), which compensate fors by the turning of cross sections a increase in the angles of attack at the bend. Also deteriorated, in comparison with the MFI layout, characteristics at supersonic speeds, which was caused by drag divergence and by large displacement of aerodynamic focus. Unacceptable aerodynamic buffeting was another shortcoming in the diagram. It appeared with the rendezvous of two incident vortex flows: one - from wing leading edge, another - from the near-fuselage rolls. In the course of the tests of the experimental aircraft of X -29, created by American company Grumman Of aircraft Of corporation and passed tests with 1984- GO on 1992 on the base “Edwards” in California, means for dealing with this phenomenon so they were not found. To conquer the buffeting expected with the aid of that finished on the series Su-27 and MiG-29 technologies of the droop nose of leading wing edge, which was used also on S-22. Works headed chief designer V. S. Konokhov. S-22 was executed according to canard configuration forward sweep, had one engine and takeoff weight in the limits of 20-24 tons. The complete package of working documentation was released on it. However, in the course of designing the aircraft it was explained that the construction of machine was overloaded. This required the radical revision of project, creation actually of new fighter. After considering work experience and being based on the existing scientific technical reserve, in OKB OF P.O. Sukhoi they approached the development of the new twin-engined forward sweep fighter, which received the index “S-32”. The development of design headed chief designer [M]. a. Pogosan. On one of the versions Of S.32 it was intended to equip with two RD -79M turbofans (2 X of 18,500 kg) with the system of the thrust vector control (modernised version of engine RD-79, created for the VTOL aircraft Yak-141). Subsequently was accepted the solution to establish to the fighter the engines of the fifth generation AL -41f (2 x of 20.000 kg), supplied with TVC. With new turbofan it would obtain the ability to accomplish prolonged cruising supersonic flight without the use of a afterburner: with the creation of the aircraft Of S.32 the most serious attention it was given to questions of reduction in the radar distinctness (in this region OKB [im]. OF P.O. Sukhoi it had available significant experience, obtained in the course of developing the heavy bombers, in particular - aircraft T -4MS). The specific contribution to the formation of the configuration of FSW fighter introduced the design project leader [NPO] “Zvezda” G. Severin, who proposed the fundamentally new concept of the catapult seat of the variable geometry, the ensuring to pilot the possibility of conducting maneuverable dogfight with considerably the higher, than on the previous fighters, g-forces. This made it possible to maximally use maneuverable advantages of aircraft with the sweptforward wing. The program of the building of aircraft carriers in THE USSR collected the revolutions (two aircraft carriers - “Tbilisi” and “Varyag” they were already in to float, atomic “Ul'yanovsk” it was already placed); therefore in carrier-based aviation of prospect they were good. To the ship-based derivative of the fighter, named Su-27KM and was released preliminary design in 1988 g. it was proposed BY VMF as a deep modification of Su-27 c.c. - 33). The need for superiority of the new aircraft over analogue - F -14D most up-to-date at that moment determined installation of two engines and maximum takeoff weight - to 40 tons. But the takeoff of so heavy a aircraft from the ramp was complex, and catapult had to appear only in “Ul'yanovsk”. Was also problem with fastening of catapult to the front rack of aircraft - on Su-27K the rack has the rear drag strut, which with the acceleration worked in tension, while because of the layout on Su-27KM the strut of front rack was from the front, and it worked on the compression. Therefore basic mode had to be takeoff from the ramp. But calculations showed that the aircraft does not manage to collect the necessary velocity with the acceleration on the deck without the catapult, necessary for the takeoff without the sag of lower than the edge of deck. Here and it had to rescue FSW, that has the higher bearing capacities at the high angles of attack and furthermore on BRAIDS the disruption began from the higher angles. All this made it possible to realise ballistic takeoff from the ramp, i.e., at the moment of gathering from the ramp the lift of wing still less than the weight of aircraft, and it moves not as aircraft, but as the deserted stone, along the ballistic trajectory (with the angles of attack, close to the critical for FSW, continuing acceleration due to th e engines operating on the afterburner. [Dostignuv] of the peak of trajectory, aircraft begin to be squandered down, the sag could be 10-15 metres from the upper point in the trajectory, but to the count of the increasing velocity and very high angle of attack FSW it " caught” machine, and in the descending branch of trajectory, approximately at the level of the shear of ramp, ballistic trajectory passed into the normal climbing flight. The schematic FSW with the developed of mechanisations and the dual tail assembly thus appeared, since the [sorokatonnyj] aircraft with the common wing with the takeoff from the ramp simply would fall outside - lift effectiveness at the high angles of attack of common wing it did not be sufficient for the creation of the required lift. Stalling in common wing begins with the smaller angles of attack in comparison with FSW. Machine had to have landing hook and added outer planes of wing. It was intended to use elements 'Stealth' in the configuration of machine - for this, in particular, fins were sloped inward. Aircraft it was planned to equip phased array radar. During May of 1989 g. with the resolution of the military- industrial commission of Council of Ministers in the number of other themes the development Su-27KM was closed, and [NIER] and OKR for S -32 continued in basic due to the personal means OKB. At the end 1980- X began work on preparation for building of the test batch of aircraft. With the attraction of Irkutsk aircraft plant were intended to gather 3 units - 2 “flying” even 1 for the static tests. After 1991, when the defence expenditures of Russia sharply were reduced, it was necessary to limit to two experiment machines. However, subsequently financing program actually ceased. In these conditions OF OKB found the possibility to continue works in the initiative-taking order on its own means. In the beginning 1990- X of years was constructed only one “experimental” aircraft, which received index “S -37”. For the first time the photo of model S -32 was published in the journal “herald of air fleet” (March-April 1996 g.)
rousseau said:That photo you taken while you were lying under abdomen would be rare and more interesting ;D
rousseau said:That photo you taken while you were lying under abdomen would be rare and more interesting ;D
Ogami musashi said:The SU-27KM was designed AFTER the S-37??
Is there any info on that article about aerodynamic performance of the SU-27KM?
Ogami musashi said:There's one famous picture of the presentation of the RC mock up to officials, the configurations was the same than the 3D pictures aboves but wings tip had Sorbstiya nacelles on each sides.