Source: http://code7700.com/v-2.htm
Timestamp: 2019-04-26 14:10:06+00:00

Document:
V2 Safety Speed is aptly named: it gives you a minimum climb rate with an engine out with a margin of safety over stall and controllability speeds. You can even maneuver, though perhaps while sacrificing the climb.
Once you've made the decision to takeoff, V2 is your most important speed. In a Gulfstream PlaneView aircraft, keeping your speed between the "2" and the target triangle will keep you flying.
V1 means takeoff safety speed.
(3) 1.10 times VMC established under § 25.149.
(3) A speed that provides the maneuvering capability specified in § 25.143(h).
The airplane must reach V2 before it is 35 feet above the takeoff surface and must continue at a speed as close as practical to, but not less than V2, until it is 400 feet above the takeoff surface.
(a) The takeoff flight path shall be considered to begin 35 feet above the takeoff surface at the end of the takeoff distance determined in accordance with § 25.113(a) or (b), as appropriate for the runway surface condition.
(ii) The weight equal to the weight existing when the airplane's landing gear is fully retracted, determined under § 25.111.
(B) The degradation of the gradient of climb determined in accordance with § 25.121(b) is greater than one-half of the applicable actual-to-net takeoff flight path gradient reduction defined in § 25.115(b).
Landing VREF 40° Symmetric for -3° flight path angle.
1 A combination of weight, altitude, and temperature (WAT) such that the thrust or power setting produces the minimum climb gradient specified in § 25.121 for the flight condition.
2 Airspeed approved for all-engines-operating initial climb.
3 That thrust or power setting which, in the event of failure of the critical engine and without any crew action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified for the takeoff condition at V2, or any lesser thrust or power setting that is used for all-engines-operating initial climb procedures.
You will have a margin of safety above VSR Reference Stall Speed and VMC Minimum Control Speed.
You will be able to climb with an engine out, gear retracted, flaps at their takeoff setting, and above ground effect by at least 2.4% (two engine aircraft), 2.7% (three engine aircraft), and 3.0% (four engine aircraft).
Figure: Takeoff Safety Speed V2 Flaps 20°, from Gulfstream G450 Airplane Flight Manual, § 5.5-8.
[G-450 AFM § 5.1-3] V2, TAKEOFF SAFETY SPEED - the target speed to be attained at the 35 foot height following an engine failure.
All of these are taken from sea level, 30°C, Flaps 20°.

References: § 25
 § 25
 § 25
 § 25
 § 25
 § 25
 § 25
 § 5
 § 5