DC-3s

Interesting, and sad. I imagine the DC-3 probably wasn't built IAW current transport category certification criteria? As in, to my knowledge, there shouldn't be a part of the SE profile where one is ever below (or even very close to) Vmc, right? Or would this be more of a function of the engines installed, having not been part of the original certification? I'm not inigio, but I do presume a higher torque/higher power engine with same tail might create problems?

Digging a little deeper into CAR 4 and found this:

§ 4b.114 Take-off speeds. (a) The critical-engine-failure speed V1, in terms of calibrated air speed, shall be selected by the applicant, but it shall not be less than the minimum speed at which the controllability is demonstrated during the take-off run to be adequate to permit proceeding safely with the take-off, using normal piloting skill, when the critical engine is suddenly made inoperative. (b) The minimum take-off safety speed V2, in terms of calibrated air speed, shall be selected by the applicant so as to permit the rate of climb required in§ 4b.120 (a) and (b), but it shall not be less than (1) 1.20 Vs1 for two-engine airplanes,(2) 1.15 Vs1 for more than two engines,(3) 1.10 times the minimum control speed VMC established under § 4b.133.(c) If engine failure is assumed to occur at or after the attainment of V2, the demonstration in which the take-off run is continued to include the take-off climb, as provided in paragraph (a) of this section,shall not be required.

§ 4b.133 Minimum control speed, VMC. (a) A minimum speed shall be determined under the conditions specified in this paragraph, so that when the critical engine is suddenly made inoperative at that speed it shall be possible to recover control of the airplane with the engine still inoperative, and maintain it in straight flight at that speed, either with zero yaw or, at the option of the applicant, with an angle of bank not in excess of 5°. Such speed shall not exceed 1.2 Vs1 with (1) Take-off or maximum available power on allengines,(2) Rearmost center of gravity, (3) Flaps in take-off position,(4) Landing gear retracted,(5) Cowl flaps in the position normally used during take-off,(6) Maximum sea level take-off weight, or such lesser weight as may be necessary to demonstrate VMC,(7) The airplane trimmed for take-off,(8) The propeller of the inoperative engine windmilling, except that a different position of the propeller shall be acceptable if the specific design of the propeller control makes it more logical to assume the different position,(9) The airplane airborne and the ground effect negligible.


So it appears the CAR certification has a margin to maintain at Vmc or above for controllability and climb performance.
 
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