Sukhoi TPFI or what should be Su-27

At mid 60s, in Soviet union was born the PFI (Perspektivnyj Frontovoj Istrebitel - perspective frontal fighter) project. It was aimed to develop the fighter, that could fight with american F-X. But the specifications were too strong and they could not be achieved by single type of aircraft. So after strong lobby of A. I. Mikoyan, the project was divided into light LPFI and heavy TPFI fighter.

As the part of TPFI program, Sukhoi worked on two different proposals. First group derived their proposal from heavy intercontinental bomber Sukhoi T-4MS (200). The main characteristic was maximal and tactical range so in the aircraft had to be place for 9000 kg of fuel. The modified flying wing schema was applied and the design received designation Schema 6. Maximal take off weigh was estimated at 25 – 30 tons. It has very thin fuselage because of strong L/D ratio, so it had to use four smaller engines with half thrust instead of standard Saturn/Ljulka AL-31F.




Second proposal called Schema 7A had integral fuselage with two separate engine nacelles under it. Vertical and horizontal tail was also doubled. This design was developed by young MiG engineers, who moved to Sukhoi at early 60s. At TsAGI, work on this concept was divided into three problems. First was eddy aerodynamics, then integral detention between wing and fuselage and finaly adaptive wing. It was tested on more than 20 small aerodynamic models.




This design was selected in 1972 for further development and in 1977, the Sukhoi T10-1 prototype was ready for flight.




But it has many problems, so primary engineer Simonov proposed, that basic schema should be used again, but everything other will be made once again from the beginning. Then the Sukhoi T10S or T10-15 was born and we know it now as Su-27 Flanker.

Again, very impressive

Although the first sheme of the t10 TPFI looks like an Aurora type aircraft, it's amazing how they kept these very fluid lines to create the Su-27.

Ooh nice find. 4 engine for a fighter? Is that effective? I'd imagine it would have high drag since it's so wide, and having 4 engines to push against the high drag means high fuel consumption. This shape could be pretty manoeuvrable though

That Su-T10 looks really cool. I really like the curves it has in the design. A really nice find, thanks!

About the engines.... what matej says is the oposite... they put 4 small engines to make a thin fusselage... it sounds like a good idea...