B777 X wind oddities
the B777 has a couple of very minor unusual crosswind characteristics:
Both 200 & 300 in a strong crosswind will (without rudder input) will initially diverge track towards the downwind side... up to approximately 60kts, thereafter the aircraft will start to diverge track towards the windward side of the runway. The B747/744/757/767, MD11, A300, A320, A330 and A340 don't do this... The -200 simulator does replicate this characteristic.
The B777-300 in a strong crosswind, above 35kts component, when doing a decrab, the cockpit (pilot eye) lateral position relative to the runway does not move downwind, the gear position shifts upwind. A B747/744 or B767 does the opposite, as do long body Airbus', the pilot eye position moves downwind, and the gear position remains fairly constant in relationship to the runway centerline. -200 simulator doesn't do this, nor does the plane, -300 simulator unknown.
In respect to the lateral forces on touchdown, the aircraft acts as a normal plane with the cg forward of the gear, and will align fairly tidily with the aircraft track as a natural dynamic. The lateral load at touchdown is quite high in such a case, landing with full decrab, but if the pilot has applied a yaw input prior to the touch, it makes a significant reduction to the peak lateral g recorded and felt in the aircraft. As long as the yaw rate has been initiated, there is a lessening of the peak acceleration going from no yaw* to the inertially developed rate.
A similar issue occurs in the measurement of landing g, if the data analysis is merely based on peak recorded values; the accelerometer is not at the cg, or at the centroid of all forces, and records both vertical acceleration against the fixed body axis, and also the rotation of the body. So a late flare will result in additive accelerations being measured, that of the pitch rate and the gear rebound. (simplistically). The -300 accelerometer is... almost exactly the fuselage plug size forward of the -200's (surprising as the location is determined normally by analysis of the natural fuselage harmonic node locations, and is located at or near a node...) and the screening value for hard landings where applied is about 0.2g higher as a result to give rational data. Same issue apples for the lateral g sensing.
In relation to the simulator fidelity in general, the landing phase is not a bad representation at all, and is required by existing MOS to be valid. The values of almost all parameters of static and dynamics is in the the region of no more than 10% (very simplistically) from flight data, and the time transport delays are pretty small. The simulator problems of fidelity should (if the sim is being maintained with any semblance of quality assurance) only be significant outside of the normal operational envelope. Within the envelope the data has to have been either recorded or modeled for validation. The biggest problem is wherever the operation encounters non linear effects such as cross coupling in a stall condition.
Fidelity issues of note were a 3 holer (XXL size) fully stalled at 630,000 climbing at 6000 FPM, with 186,000 lbs of thrust installed, small twin jet stalled with full rudder applied, and ailerons controlling the roll comfortably (accident data shows same aircraft condition cross coupling with a roll rate in excess of 180 degrees a second). Latter case dynamics are now updated, finally, and may be more representative of reality, an off center axis entry into the microburst model will result in departure if the plane is stalled while at a high yaw rate due to the microburst. (now crew occasionally complain about the "unreasonable" handling of the simulator in this situation). A related issue that was noted on a series of sims evaluated a few years ago was that out of wind aileron did non give any roll effect in crosswinds up to 50kts, until the nose wheel was lifted off the ground, then it made quite a difference. In this case there are aerodynamic and geometry issues that effect the roll authority at low angels of attack, but there was no discernible effect identified by the meta centric height at any of the gear. Flight data showed that real planes do notice aileron input and crosswind effects, particularly swept wing aircraft.
The NRT thread says more about things unrelated to crosswinds, and if recent mutterings from Randy Babbitt are valid, are not isolated geograpically, but are an indication of global systemic malaise.
Warm Springs, GA