But I think even if J-20 is not designed to has a 3D TVC engine, it is not inferior aircraft.
Remember this the next time anyone criticizes the F-31 for not being able to supercruise -- as in 'inferior' to the J-20.
To date, there are no credible evidences that the J-20 have TVC engines. Every images presented so far have been of asymmetric nozzle openings, which are common with twin engines fighters, which gives the illusion of having TVC engines.
The real proof is on ground operations.
Prior to every takeoff, twice the pilot will do what is called 'cycling' all the major flight components, which includes the engines. The first cycling of these components is when the jet is in what we who have actual military aviation experience call 'in the chocks'. This is before taxiing to the runway. This is after the pilot is in cockpit, engine started, INS spooling up, standby compass system orienting itself, and flight control system are going thru their programmed self tests.
If the jet is equipped with TVC engines, in the chocks is where and when the pilot will cycle the TVC nozzles.
The nozzles will have their asymmetric positions
THIS obvious...
https://defence.pk/threads/chengdu-...news-discussions.111471/page-515#post-9143633
This is unambiguous. No visual illusions. No aspect aberrations. Your own post showed it.
In the chocks, prior to taxi, the pilot will be assisted by at least three ground crews: the crew chief and two assistants, the crew chief will station himself in front of the jet in clear visual sight of the pilot, the assistants will one per side of the jet.
The pilot will be in wired communication with the crew chief. The crew chief will be in hand signals communication with the assistants.
Once the flight control system completed its self tests, the pilot will begin cycling the flight control surfaces to their fullest extent. Ailerons, rear horizontal stabs, and vertical stab(s). All surfaces must deflects to their
FULL mechanical stops, meaning the hydraulic actuators must travels to their maximum extension and withdraw to their shortest position, taking the flight control surfaces with them. All this time, if the crew chief notices any surface that does not travel to match the other surface, troubleshooting begins. If maintenance is required, in maintenance lingo, it is called a 'red ball'.
https://en.wikipedia.org/wiki/Red_ball
Term used by the US Air Force, typically on the flight line, to identify supply or service requests that are needed urgently to avoid mission failure, and thus given highest priority.
We do it this way and have no doubt the PLAAF does the same. The actual translated words maybe different, but whatever they are in Chinese, the intent is still the same: Get the maintenance truck with its parts bin to the jet immediately.
If the Launch truck cannot effect repair on a 'red ball' call, then it is a mission failure and the pilot is moved to the back up jet. If there is no back up jet, then the day's sortie count will be minus one.
Assume that the flight control system passed all checks. Now, if the jet is equipped with TVC engines, the pilot will first cycle the nozzles' openings, the crew chief's assistants will hand signal if there is anything wrong, then the pilot will manually cycle the nozzles' TVC movements. Just like the flight control system, the TVC nozzles must move to their
FULL mechanical limits.
Assume the jet passed all checks in the chocks. Now the pilot will call to remove the wheel chocks. The crew chief will signal that removal thus: both hands into fists, thumbs up, then flip the thumbs to the sides, pointing outward.
The assistants will move in, kick the chocks out, and once both are cleared of the wing tips, the crew chief will marshal the jet out of its parking space.
The pilot will taxi to 'end of runway' (EOR) and here is the second cycling process begins. At EOR, there is no need to have the flight control system go thru its self tests again. The ground crew will perform a final inspect of the jet's outer condition. All panels must be visually flushed with the body. All pins, such as landing gears and weapons safes, must be removed. Tires must be in good operating condition such as no fibers visible. No running drips of any fluid, unless it came from the weather. Someone will hover his hand over the brakes to make sure they not overheated because that would indicate dragging brakes from the chocks to EOR, which would abort the mission for that day. Dragging brake is not possible to fix on a red ball call.
If the jet is equipped with TVC engines, EOR is where there
MUST be a final check of the nozzles operations the same way as when the jet was in the chocks.
The ground operations I described above are common to all air forces that are serious about preserving their jets. The steps came from WW I and they tried and trued, from peace to war times. Much of what an aircraft can do, we can infer from ground operations.
So far, of the many ground photos of the J-20, there is not a single photo of a drooping nozzle when hydraulic pressure is off, or when the jet is in the chocks going thru its preflight checks, or when the jet is in EOR readied for takeoff.
@Deino @ptldM3 @pakistanipower @Taygibay @Tiger Awan