All has not gone well so far. So far T-50 development has been delayed two years and more delays are expected. The current plan is for mass production starting in 2019. This is according to India, which is collaborating with Russia in the development of this Russian designed fighter. The delay worries India because they are picking up half the $6 billion dollar development cost. These delays mean rising costs. Moreover, the $6 billion only covers work on the basic aircraft. All the avionics will be extra, and India is unclear of how much extra. India has had serious (and expensive) problems with Russian development cost projections before. Undeterred, India planned to buy 250 (now reduced to 200) of the new T-50s, for about $100 million each. An increasing number of Indians now see the T-50 possibly following the same cost trajectory as the F-22.
Russians and Indians have been doing a lot of tinkering since the first T-50 flew. While the T-50 is the stealthiest aircraft the Russians have, it is not nearly as stealthy as the F-22, or even the F-35 or B-2. The Russians are apparently going to emphasize maneuverability instead of stealth. India wants more stealth and would prefer a two-seat aircraft. There are also problems perfecting the engines for the T-50 and the defensive electronics are proving difficult to perfect. This puts the T-50 at a big disadvantage against the F-22 or F-35, which try to detect enemy aircraft at long distance, without being spotted, and then fire a radar guided missile (like AMRAAM). These problems are apparently the main reason for the two year delay.
The Russians want to sell their "Fifth Generation Fighter" (the T-50, which they admit is not true 5th Gen) to China, India, and other foreign customers. With the Indian participation, Russia now has the billions of dollars it will take to carry out the T-50 development program. India is not just contributing cash but also technology and manufacturing capability.
The T-50 is a 34 ton fighter that is more maneuverable than the 33 ton Su-27 it will replace, has much better electronics, and is stealthy. It can cruise at above the speed of sound. It also costs at least fifty percent more than the Su-27. That would be some $60 million (for a barebones model, at least 50 percent more with all the options), about what a top-of-the-line F-16 costs. The Su-27 was originally developed to match the American F-15.
Russia is promising a fighter with a life of 6,000 flight hours and engines good for 4,000 hours. Russia promises world-class avionics, plus a very pilot-friendly cockpit. The use of many thrusters and fly-by-wire will produce an aircraft even more maneuverable than earlier Su-30s (which have been extremely agile).
The T-50 is not meant to be a direct rival for the F-22 because the Russian aircraft is not as stealthy. But if the maneuverability and advanced electronics live up to the promises, the aircraft would be more than a match for every fighter out there except the F-22. If such a T-50 was sold for well under $100 million each there would be a lot of buyers. For the moment the T-50 and the Chinese J-20 are the only potential competitors for the F-22 that are in development. Like the F-22, T-50 development expenses are increasing, and it looks like the T-50 will cost at least $120 million each (including a share of the development cost) but only if 500 or more are manufactured. Russia hopes to build as many as a thousand. Only 187 F-22s were built because of the high cost. American developers are now seeking to apply their stealth, and other technologies, to the development of combat UAVs. Thus by the time the T-50 enters service, in 7-10 years, it may already be made obsolete by cheaper, unmanned, stealthy fighters.