Recent news about the Russian PAK FA, and its Indian counterpart the FGFA, has unveiled numerous shortcomings within the aircraft. Indian officials have voiced concern over the aircraft's limited reliability, inadequate radar, and poor stealth features. In December, patents from the Sukhoi Design Bureau were released; these documents detail the limits of its radar reduction features.
Russia can't deliver on Fifth Generation Fighter Aircraft: IAF - By Ajai Shukla
“Business Standard has reviewed the minutes of that meeting. The IAF’s three top objections to the FGFA were: (a) The Russians are reluctant to share critical design information with India; (b) The fighter’s current AL-41F1 engines are inadequate, being mere upgrades of the Sukhoi-30MKI’s AL-31 engines; and (c) It is too expensive. With India paying $6 billion to co-develop the FGFA, “a large percentage of IAF’s capital budget will be locked up...On January 15, the IAF renewed the attack in New Delhi, at a MoD meeting to review progress on the FGFA. The IAF’s deputy chief of air staff (DCAS), its top procurement official, declared the FGFA’s engine was unreliable, its radar inadequate, its stealth features badly engineered, India’s work share too low, and that the fighter’s price would be exorbitant by the time it enters service."
The FGFA program is looking like another example of Russian-Indian "co-development" in which India pays an exorbitant sum of money to Russia for only marginal improvements in its domestic defense industry resulting from Russian technology transfers.
PAK FA stealth features patent published - By Piotr Butowski
"The papers claim that the radar cross-section (RCS) of an Su-27 was in the order of 10-15 m 2 , with the intention being to reduce the size of the RCS in the T-50 to an "average figure of 0.1-1 m 2...In particular, the patent spells out the benefits of internal weapons carriage, s-shaped engine air ducts, (which were considered but are actually not implemented in the production PAK FA), and the use of radar blockers. It adds that the inlet guide vanes of the engines' compressors generate "a significant portion [up to 60%] of the radar cross-section of the airframe-powerplant system in the forward hemisphere" and that this is reduced by using radar-blocking devices and radar-absorbing coatings in the walls of the air ducts."
David Axe's details the PAK FA's reliability problems further in an article called, The Indians HATE Their New Russian-Made Stealth Fighter.
"Press reports in 2013 indicated that Sukhoi was having problems with quality control in the T-50 effort. At least one of the prototypes needed patches on its wings to keep from falling apart during high-stress maneuvers." - David Axe, 2014
The engine blades for the PAK FA are easily visible in the image above.
For comparison, Global Security cites the F-22A's frontal radar cross section (rcs) at .0001m^2 and the F-35 has a frontal rcs of .0015m^2. The PAK FA's rcs is subsequently several orders of magnitude larger than its American counterparts.
Author's Note: I am still working on the Raptor article, but I'm not able to work on blogging as much due to college work. However, I will try to consistently publish at least one article per week.