Wednesday, March 9, 2011
© Lexington Institute; reproduced by permission
Aerospace experts scrutinizing images of the Chinese J-20 fighter that first began appearing on the internet in late December have developed a more nuanced view of the plane's features than what was available in early reports.
Although the J-20 resembles the outline of the stealthy F-22 Raptor when viewed head-on in its forward aspect, the plane clearly lacks many of the features that make Raptor the most capable air-to-air combat system in history. On the other hand, these same experts believe that over time the Peoples Liberation Army Air Force can evolve the J-20 into a formidable combat aircraft -- especially given the fact that it is expected to operate in or near Chinese airspace, where it will greatly outnumber any attacker's planes.
Early reports that the J-20 exceeds 70 feet in length appear to be wrong. By comparing the scale of the aircraft with adjacent reference objects whose dimensions are known, experts have determined that the fighter is 62 feet long -- the same length as the F-22, and not much different from the 64 feet of the F-15C fighter. Based on overhead imagery and other inputs, wingspan looks to be about 41 feet, also similar to F-22 (45 feet) and F-15C (43 feet). However, the wing area of roughly 630 square feet much more closely resembles the 608 square feet of the F-15C than the 840 square feet on the F-22; this matters a great deal in terms of range since fuel is stored in wing areas.
The J-20's top speed is judged to be below Mach 2, meaning it is significantly slower than an F-22 or F-15C. Little is known about the performance features of the J-20's twin jets, which may be based on technology from the western CFM-56 commercial powerplant first exported 30 years ago. The steady-state thrust provided by the engines is probably similar to the 29,000 lbs of the F-15C, but greatly inferior to the 48,000 lbs generated by the two F119 engines on the Raptor (J-20 maximum thrust of 60,000 lbs comes closer to the 70,000 lbs of F-22, and surpasses the 48,000 lbs of F-15C).
The J-20 does not have the supercruise feature of the F-22 that allows the latter plane to fly at high speed without consuming excessive amounts of fuel, which puts the J-20 at a decided disadvantage given that it carries about 25 percent less fuel internally than the F-22. It also does not have the vectored thrust of the F-22 that provides enhanced aerial agility; the Chinese appear to have modified the fixed exhaust nozzles on the J-20 with an eye to misleading western observers concerning how capable the propulsion system is.
The J-20 airframe incorporates extensive low-observable (stealth) technology into its forward aspect, although it is more readily tracked from side and rear angles. However, even in the forward aspect some design features such as the engine inlets appear sub-optimized for reduction of radar cross-section. It is not clear how extensively designers have used radar-absorbing materials. It is also not clear what kinds of on-board electronics the J-20 will eventually carry in its operational configuration. Electronic sensors, processors and datalinks are the heart of the F-35 Joint Strike Fighter, greatly surpassing the performance of even those on the F-22.
While the J-20 superficially resembles fifth-generation fighters such as the F-22 and F-35, experts do not believe Chinese designers will be able to produce an airframe that comes close to matching the maneuverability, survivability, lethality or situational awareness of an F-22 or F-35.
However, they may not need to if they can lure enemy fighters into Chinese airspace where they have other "home court" advantages. (ends)
Posted by Steve Douglass at 10:00 AM
After (a total) of 365 days in orbit and 148 million space miles logged -Discovery is home for good.
Posted by Steve Douglass at 9:02 AM
Space shuttle Discovery’s payload bay doors are closed and everything continues to proceed on schedule for this morning’s landing attempt.
Weather currently is both forecast and observed “go.” Astronaut Rick Sturckow is flying weather reconnaissance at Kennedy Space Center, where winds are forecast to be high, but within limits for runway 15. Sturckow will fly runway approaches to assess conditions for Discovery’s landing. The winds from the southeast (130 degrees) are forecast to be 15 knots, peaking to 23 knots, providing a 10 knot crosswind and 21 knot headwind.
At this time, winds are only six knots, peaking to 12 knots. End of mission weather flight rules state that daylight crosswinds may not exceed 15 knots, headwinds may not exceed 25 knots and tailwinds may not exceed 15 knots. Also, peak winds may not be greater than 10 knots over the average wind.
At 8:22 a.m., Mission Control is expected to give a “go” for Discovery’s computers to begin running the Ops 3 entry software. At 8:52 a.m. a “go” is expected for crew suit up. The “go” for deorbit burn is expected by 10:32 a.m.
The deorbit burn is scheduled for 10:52:09 a.m. and will lead to a landing at 11:57:44.
Posted by Steve Douglass at 5:32 AM