The U-2S may be the most challenging aircraft in your entire fleet. Essentially a drastically over-powered sailplane, the flight envelope of the U-2S is very narrow and it is easy to exceed the aircraft's limitations. Please take a moment to review this information to get a better understanding of this unique aircraft. Also take a moment to read the U-2S Flight Experience, which will provide real-world information on how this plane is actually flown.
The U-2S is a comparatively light aircraft with a tremendous thrust/drag ratio. To complicate matters, it is a tailwheel aircraft. It is easy to overspeed and bang the tailwheel on the runway during rotation. To avoid this, use a little nose-down trim and rotate very gently. Takeoff at a normal aircraft weight will be rapid, with excellent acceleration. At light weights, the U-2S will be airborne in just a few hundred feet and the acceleration will be dramatic. Climb is normally accomplished with full throttle at an indicated airspeed of 100 knots. This will yield an initial rate of climb approaching 10,000 feet per minute and an inital aircraft attitude of nearly 45 degrees nose-up. This climb rate will drop off rapidly with altitude. It is a real challenge to maintain the proper climb speed all the way to 70,000 feet.
Normal cruise for the U-2S is 0.72 Mach. This equates to an indicated airspeed of around 106 knots at 70,000 feet. The real U-2S utilizes what is known as a "cruise climb" to reach the higher altitudes. This is accomplished by setting the Mach hold at 0.72 Mach; the aircraft then controls the speed by adjusting the pitch while leaving the throttle setting unchanged. As the aircraft burns fuel, it will become lighter and will climb at approximately 100-200 fpm with the Mach hold enabled. In Flight Simulator 9, this kind of control is not possible with the usual autopilot configuration. It will be very difficult to launch a cruise from 70,000 feet. The best way to simulate the actual procedure is to begin a climb from 56,000 feet at a rate of climb of 100-200 fpm and reach cruising altitude. A normal cruising weight is around 25,000 pounds at 70,000 feet.
Descent is accomplished by reducing the throttle to idle, deploying the spoilers and speedbrakes, and lowering the landing gear. Even with all these devices in play, the U-2S is reluctant to come back to Earth. A normal descent from cruise altitude will take around 40 minutes, with a rate of descent of 1500-2000 fpm. In a clean configuration, the U-2S has a glide ratio of 28:1 at best glide speed of 109 KIAS. This means the aircraft could travel 370 statute miles in a power-off glide from 70,000 feet.
Landing is extremely challenging. Even with the spoilers, speedbrakes, flaps, and gear deployed, the U-2S has a terrific tendency to float. The final approach speed is very slow, around 85 KIAS, and the speed across the runway threshold is just 75 KIAS, or 1.1 times the stall speed with flaps at 35 degrees for a landing weight of 19,000 lbs. The normal procedure for landing a U-2S is to have an automobile racing alongside, the driver calling out the altitude AGL to the pilot. When the distance between the main landing gear and runway is 1 foot, the pilot pulls back on the yoke to stall the aircraft onto the runway tailwheel first. The AlphaSim U-2S can be landed in a similar fashion by opening up a separate, external view window to monitor the altitude AGL as you begin your final approach.
It is very easy to overspeed the U-2S, either by exceeding the maximum indicated airspeed or Mach number. The maximum IAS for the U-2S is 240 KIAS, a speed that can be reached in just a few seconds with full power in level flight at low altitude. Similarly, the maximum Mach number can also be easily exceeded at altitudes well above those used by modern jetliners. Since the U-2S was meant to operate at high altitudes, it normally never lingers at the lower flight levels. Rather than using the throttle to control speed, simply adjust the aircraft pitch. In real life, the U-2S is never at a constant altitude; it is constantly climbing as it burns off fuel. At cruising altitude, the difference between maximum Mach number and the aircraft's stall speed is very small, and the airspeed differential between the onset of the stall buffet and Mach buffet is minimal. This "window" is called "Coffin Corner" and strict attention from the pilot is required when flying in this configuration. Similarly, the aircraft is very susceptible to crosswinds due to its large wing area and relatively light weight. It is also generally unstable at higher altitudes and requires the autopilot for hands-free flight.
The unloaded weight of the U-2S is 16,000 pounds. A 2,000 pound payload is standard, but you may adjust this using the Fuel/Payloads menu. The maximum weight of the aircraft is 41,000 pounds. The normal landing weight is 19,000 pounds. The clean stalling speed at this weight is 72 knots IAS, while the stalling speed in landing configuration (35 degrees flaps, gear down, spoilers and speedbrakes deployed) is 68 KIAS. The stall speed with full flaps and gear down at this weight -- without spoilers or airbrakes -- is 59 KIAS. (The differences in these speeds are explained by the loss of lift that occurs with the spoilers deployed.) The aircraft would not normally be landed in using full flaps without spoilers unless a flight was aborted and had to be landed at a high weight. Note that Flight Simulator combines the spoiler/airbrake function so it is not possible to land with only the airbrake deployed.