I was talking about Russian capabilities in general; you cannot engineer a sophisticated fifth generation Raptor killer from ether.
Does the capability exist in terms of skilled manpower, funds, institutes and industrial base? Like India, the best Russian minds are no longer in Russia; they've gone elsewhere in pursuit of a better life. Those that remain are found in private or foreign institutes and not the state owned ÐžÐ±ÑŠÐµÐ´Ð¸Ð½Ñ‘Ð½Ð½Ð°Ñ ÐвиаÑÑ‚Ñ€Ð¾Ð¸Ñ‚ÐµÐ»ÑŒÐ½Ð°Ñ ÐšÐ¾Ñ€Ð¿Ð¾Ñ€Ð°Ñ†Ð¸Ñ – this shouldn't come as a surprise to you since the best and the brightest in India shun the DRDO just like their Russian counterparts.
When I talked about demonstrated capability, I was referring to evidence of Russian capability in the public domain be it civilian aerospace, the auto industry, energy or any other space where the Russians are so far ahead of their western counterparts that they are acknowledged world leaders? Do the Russians make technologically superior automobiles? I don't think so, had that been the case my Russian friend and fellow forum member would've been speeding down the undivided highways of Moscow in his Volga and not a BMW M3. The one area where the Russians apparently lead between 1957–1999 was space launch vehicle reliability, the below graphic shows the Russian vehicles enjoyed a success rate of 93.5% a 6% gain over the US reliability score of 87.5%.
Post glasnost the Russian success rate has declined considerably; some attribute this to lack of funding others suspect that Soviets era launches were not as successful as originally claimed. Soviet records are still being catalogued but experts opine it's a combination of both factors.
Returning to the discussion on F-22, traditional aircraft materials such as aluminum and steel make up about 1/5 of the F-22's structure by weight. The high performance capabilities of the F-22 requires the significant use of titanium (42 % of all structural materials by weight) and composite materials (24 % by weight), which are both stronger and lighter weight than traditional materials, and offer better protection against corrosion. Titanium also offers higher temperature resistance.
Materials such as Thermoplastic, BISMALEIMIDE (BMI) resins and Titanium (Ti-62222) create its own unique engineering challenges. Thermoplastic is made from sheets of graphite fibers held together by resin, this is baked in an autoclave while nitrogen is pumped in to raise pressure forcing the fibers to blend with the resin. BISMALEIMIDE (BMI) resins are also cooked in an autoclave without the need for vacuum and pressure but both BMI and Thermoplastics present the same problem of air bubbles forming within the layers of resin and graphite weakening the structure. In addition, it is important to achieve the correct crosslinks density (linking of polymer chains) too high crosslink density results in brittleness too low will reduce strength achieving the right crosslink density largely depends on the materials and the resin.
Defective composites are unusable and must be discarded; the success of this procedure is dependent upon the quality of raw materials (fiber and resin), the process and efficiency of the machines used during the operation. A majority of the raw materials and tools are dual use technology and is aggressively export controlled.
The use of composites in previous Russian aerospace ventures is limited to a few components and there is no evidence to suggest that the raw materials and equipment needed to manufacture over three hundred airplanes with over 40% composite materials content can be achieved locally –
Russian industry no longer has the capability thanks to years of post perestroika neglect. Even at the peak of Soviet glory, Russian equipment was not renowned for build quality this is evidenced by the number of crashes due to technical failure of Russian hardware.
I re-emphasize capability is not just limited to technical capability and know-how it is the ability of a nation's infrastructure to support a complex fifth generation fighter program simply because the
manufacturing tolerance for a 5-generation fighter is much more stringent – a structural anomaly during the thermal curing process will weaken the air frame and compromise stealth.
The process of cooking and the use of auto-clave for producing thermal-cured composites is by no means new this technology has been around for over forty years. Despite this some of the well known issues with thermal-curing such as resin timeout, auto-clave size limit and tooling cost of the auto-clave and associated test equipment is yet unresolved.
The use of thermal-curing is perhaps cost justified for building two prototypes but will be cost prohibitive for building over three hundred airplanes needed by both Russia and India. This was recognized by DARPA several years ago that more sophisticated techniques were needed to reduce cost and eliminate wastage due to defects.
The problems with thermal curing particularly the
size restriction imposed by the auto-clave is resolved by a newer technique that uses a high energy electron beam(EB) rather than heat, to initiate polymerization and cross-linking. This technique was first introduced in the US in 1994 by Northrop Grumman and Lockheed Martin with the IATA program (Integrated Airframe Technology for Affordability). The fuselage of the F-18 E/F was built entirely by EB curing at the Northrop Grumman facility. The use of EB require a different epoxy resin, unlike thermal resins, EB resins can be stored at room temperature and is cured under vacuum pressure only an additional benefit of EB curing is resistance to micro-cracking and moisture absorption.
The use of EB technique is now wide spread it has been widely adopted by Boeing, Lockheed, Dassault and EADS.
EB is not known to have been used in Russian military or civilian programs, penetration of this technology in the Russian aviation sector will be visible in the form of airplane components that require sophisticated production techniques a
good example of such a component is the laminated polycarbonate bubble canopy – I do not recall ever seeing a Russian fighter with a bubble canopy.
Perhaps these techniques will be introduced later when the PAK-FA is ready for mass production but I'm not optimistic since the Russian industry has not demonstrated the capability to produce the raw materials, the tools or the precise testing equipment and software needed to produce composite materials for over 300 aircrafts.
Next, the tooling requirement for cutting Titanium to manufacture components of the airframe is well known.
For instance, 'bulkhead 270' the center piece of the F-35 takes precision software controlled machine tools 24 hrs X 7 days to cut from a block of titanium. Since this is a critical piece of the fuselage it is tested extensively using sophisticated metrology tools.
Here is a list of some of the metrology tools used in the F/22 and F/35 program:
- Gantry CMM (Carl Zeiss IMT)
Located at the Lockheed Martin (Bethedsa, MD) facility it is used to obtain highly accurate measurements of the components such as wing skins and subassemblies used in building the F/35 and F/22 fighter. Arguably the most accurate of the large CMMs in the world it is used to scan the form, location and physical size of thousands of bores on this wing skin. The data provided by this tool is used to make real-time manufacturing corrections.
- Laser-based inspection measurement systems (Metris USA Inc. Brighton, MI) Includes laser Radar and indoor GPS metrology systems and PC DIMMS software. These systems allow defect free inspection and precise assembly of machined components specifically joining the wing to the aircraft body.
The APG-77 is unique,
it is elliptical. Each T/R module is the size of a finger nail, other advanced western AESA radars take 14 seconds to perform 120 deg six bar search pattern the APG-77 does it instantaneously. The elliptical shape of the APG-77 antenna provides a valuable clue to the low side lobe it presents many speculate it is around -70dB below the main beam, remember to qualify as a low probability of intercept (LPI) radar the main beam gain should be 55dB over the first side lobe. So the figure of -70dB is unimportant, the first side lobe is undoubtedly at least -55dB below the main beam.
The low side lobe performance of the APG-77 is achieved by the tapering the distribution of array elements on the antenna the smoother the taper from the center toward the extremity the lower the side lobe. If all T/R modules were made equal it would be easy to distribute array elements as described above – the phase error introduced as a result unachievable chip 'manufacturing tolerance' required to create identical T/R modules. The antenna array spacing should be precise to maximize power to the main beam; complex calibration is later required to achieve consistent performance.
Further, all Russian AESA production radars antennas contain visibly uniformly spaced array elements, LPI and low side lobes have not known to be achieved in this manner.
The advantage of an LPI radar is the an enemy RWR will receive its first warning only when the AMRAAM seeker is locked on giving the enemy combatant a few seconds before intercept. All this is achieved by the APG-77's transmitting several low energy pulses that are discarded by enemy RWR as clutter. These low energy returns are then assembled by the Raptors signal processers and the threat positively identified this technique is called spread spectrum transmission.
The APG-77's advanced signal processor is able to render an iSAR image of a moving target this capability is known to have been available only on dedicated air borne radars. The reason for this is the sheer processing power needed for complex calculation using the Doppler shift data was previously not possible on a small fighter jet sized aircraft it was the domain of
larger dedicated AWACS platforms like E3 and IAF Phalcon.
I can talk about the precise construction needed for the F-22 radome and its effectiveness as a bandpass / bandstop filter for maintaining LO observability but that in itself is a complex subject.
I don't mean to sound like an arrogant American, I know the short comings of the Raptor. I am not enamored by it for me its just a machine. I am looking for credible facts to prove that I am wrong and that Russia does have the capability not just to build two prototype but the capability to sustain a PAK-FA production line to build 300 Raptor killers.
