V-Speeds

V-speeds (Velocity) are the indicated airspeeds used, or airspeed limits, for the operation of a specific type of aircraft. They have to be memorized, for when you're flying you won't have time to look them up. During flight examinations, the examiner will quiz you, and they must be known.

Airspeeds have been determined by the aircraft manufacturer mathematically, in wind-tunnel testing and during flight testing. They are all documented in the aircraft's Flight Manual.

All of the values are treated as hard limits, however, failure or damage isn't automatic. For example, Vne (Never Exceed) is 164 knots. The manual describes it as "Do not exceed this airspeed in any operation", but if you fly 165kt you're not going to immediately disintegrate in mid-air. However, you are now in test-pilot territory, and the aircraft has not been tested to provide safe operations at that airspeed.

I have to have them memorized, which is why I'm writing them down. Among other things, the airspeeds are in four* different sections throughout the Flight Manual, so getting them together in one spot is useful.

For the Diamond Eclipse with the Sensenich propeller (all speeds are KIAS**):

Vne	164	Never Exceed
Vno	118	Normal Operations
Va	106	Maneuvering Speed
Vfe-to	100	Do not exceed with flaps extended in takeoff position
Vfe-ldg	78	Do not exceed with flaps extended in landing position
Vx-to	57	Best angle of climb with flaps in takeoff position
Vx	60	Best angle of climb with flaps in cruise position
Vy-to	68	Best rate of climb with flaps in takeoff position
Vy	75	Best rate of climb with flaps in cruise
Vr	44	Rotate speed (the speed that you start to lift the nose when taking off)
	52	Approach speed for normal landing, flaps in landing
	52	Balked landing takeoff speed, flaps in landing (the manual doesn't specify this, but this would probably be Vx-ldg)
	34	Stall speed, flaps landing, 0 degrees bank
	40	Stall speed, flaps takeoff, 0 degrees bank
	42	Stall speed, flaps cruise, 0 degrees bank
	20	Maximum demonstrated crosswind speed for takeoff or landing
	73	Best glide speed, flaps in cruise

* The four sections
Chapter 2 - Airspeed limitations
Chapter 3 - Airspeeds during emergency procedures
Chapter 4 - Airspeeds for normal flight operation
Chapter 5 - Performance - Stall speeds

**KIAS

Knots Indicated Air Speed - there are several speeds when aircraft are involved, including

• TAS - True Air Speed
• CAS - Calibrated Air Speed
• IAS - Indicated Air Speed

IAS is the number you read off the airspeed indicator, is the most readily available, and the one used by pilots when flying the airplane. However, it is also almost always not your true air speed, due to variations in air temperature, pressure, mechanical errors in the system, placement of the pitot, and so forth. This is worth another post in itself. Sometime.