Guys: This is a copy from B737 FCTM; as the original question was about this a/c. Note the comment that would suggest an ETP can be flown at the speed attained when the engine fails if >V2 & <V2+20.
See also the notes about bank angles v V2 (+15)
2 Engine normal takeoff.
V2 + 20 knots is the optimum climb speed with takeoff flaps. It results in the maximum altitude gain in the shortest distance from takeoff. Any speed between V2 + 15 and V2 + 25 knots results in approximately the same takeoff profile.
Note: A maximum bank angle of 30° is permitted at V2+15knots with takeoff flaps.
Engine failure during takeoff.
Adjust pitch attitude, as needed, to maintain desired airspeed of V2 to V2 + 20 knots.
The initial climb attitude should be adjusted to maintain a minimum of V2 and a positive climb. The flight director commands a minimum of V2, or the existing speed up to a maximum of V2 + 20 knots.
The initial climb attitude should be adjusted to maintain a minimum of V2. If an engine fails at an airspeed between V2 and V2 + 20 knots, climb at the airspeed at which the failure occurred. If engine failure occurs above V2 + 20 knots, increase pitch to reduce airspeed to V2 + 20 knots and maintain V2 + 20 knots until reaching acceleration height.
If an immediate turn is required, maintain V2 to V2 + 20 knots with takeoff flaps while maneuvering.
Note: Limit bank angle to 15° until V2 + 15 knots. Bank angles up to 30° are permitted at V2 + 15 knots with takeoff flaps. With LNAV engaged, the AFDS may command bank angles greater than 15°.
Thus: for B737 you will see that V2 - V2+20 (+25) is a general climb thing, while V2+15 bank angle limit is very specific. They are 2 different items. No doubt the manoeuvrability criteria was designed so that it combined well with the climb performance envelope. Sensible engineering.
Last edited by RAT 5; 6th July 2015 at 15:24.