Originally Posted by
megan
From the flight manual.
FLIGHT CHARACTERISTICS WITH ENGINE FAILURE
MULTI-ENGINE FAILURE ON ONE SIDE
During inflight emergencies involving multi-engine failures on one side, applications of large amounts of rudder and lateral control are necessary in order to maintain control when extreme amounts of asymmetrical thrust exist or are applied, Application of this control creates severe loads on the aircraft structure. These loads vary in magnitude in accordance with the degree of thrust dissymmetry, degree of deflection of corrective rudder. rate of rudder application, amount of yaw/roll displacement that has taken place prior to rudder application, abruptness with which engine thrust is removed, indicated airspeed, gross weight, center oi‘ gravity, fuel distribution, amount oi air turbulence present, aircraft configuration including flaps and landing gear positions, missile loading, external tank loading, etc. If these variables occur in certain combinations, critical structural loads can result. In view of the difficulty in controlling these variables, close observance of the following procedure will minimize the possibility of structural overload.
1. If asymmetrical thrust develops abruptly, the resulting yaw/roll tendency should be counteracted with lateral control followed by steady rudder application. Trim as required to balance control forces.
2. If thrust requirements permit, readjust the power on the remaining engines to minimize control surface deflections‘ Power adjustments should be applied slowly and simultaneously with control surface movement.
3. Avoid turbulent air and limit bank angle to 20° maximum.
PERFORMANCE - WARNING - Nonzero lateral trim resulting from inoperative engines must not be compensated for by fuel manipulation because an uncontrollable roll may occur when power is reduced on approach for landing.
This aircraft is unique in its ability to handle asymmetrical thrust conditions provided the prescribed procedures are followed. See "Multi-Engine Failure on One Side, " this section. The takeoff and climbout performance of the aircraft with inoperative engines is shown in Parts 2, 3, and 4 of the Appendix, In each case, the inoperative engines are assumed to be in the most outboard positions and all on the same side. This is the most adverse condition from the stand point of trim drag which is associated with control surface deflections. Advancing the throttles to full travel in an emergency situation will give maximum thrust. This may exceed normal engine limits. Overthrusting the engines will accentuate the aircraft control problems and reduce engine life. All instances of overthrust. as indicated by excessive EGT and/or rpm will be recorded can Form 781. See "Engine Limitations," Section V.
I'm kind of hazy on that, from only having 13,000 out of 28,000 hrs on 4 engine aircraft, but pretty sure that above VMCa2 they all would cope to an extent with a multiple engine failure on the same side. Between Vmca1 and 2, there was a bit of a choice as to what your preference was, and the outcome was dependent on having adequate clear air between the plane and the planet in order to accelerate with limited thrust on what could be controlled. (once upon a time we used to actually practice that in the plane, and that finally went to doing it in a sim, much more comfortable).
The oddity with the Buff is they had a marginal structure at the rear end, and a rudder that was designed to give excessive torsion for the amount of lateral force that may be needed. Couple that all with the design decision to go with spoilers for roll control, and you are endowing the plane with the qualities of being a bit of a beast, and not just to the other team, but to the poor schmucks that are cocooned in the plane. Design constraints in the late 40s led to the configuration that was chosen, and they have lasted some time with only a modest loss of personnel.
How bad the inherent handling of the B52 is is exhibited in the Fairchild practice disaster. While the driver and the command system got beaten up for the event, it is interesting to note that the spoiler response was being saturated quite early in the left turn that Holland entered. The speed and the bank resulted in exceeding the authority of the spoiler system, and the rudder, well, we have just commented on the rudder's authority. Occasionally, limits are there for very good reasons, bank limits on the Buff were rational, and needed to be respected. Asymmetric thrust was the last resort remaining to come out of the steepening bank, and that has not been indicated as having been attempted by the crew. Pity, McGeehan died ensuring that no other pilot in his squadron had to fly with a pilot who has a known history of operational violations.