Flight Training - July 2012 - 36

The FAA thinks highly enough of V speeds to specifically define them in the federal aviation regulations. In fact, Part 1 of the FARs includes definitions for 35 separate V speeds. All of them are important, too. However, of those 35 speeds, there are six that every pilot should know, whether he is an airline captain flying a widebody over the ocean, or a student pilot guiding an LSA around the pattern.

flights in the early days of aviation, had they only known of the importance of VR.

VR. Let’s start with VR, the speed that will set us up to get airborne in a reliable, predictable fashion. Sure, you could push the throttle all the way up, pull the controls back, and wait. You might get airborne, or you might mush along the runway creating so much drag that you never rise into the air at all. Rather than build an undesirable level of risk into our flying experience, engineers and test pilots devised the concept of a rotation VNE speed. And that’s exactly what VR is: rotation speed. Going back to the FARs, we can find specific information in Part 23 that tells us that VR is “the speed at which the pilot makes a control input, with the intention of lifting the airplane out of contact with the runway or water surface.” It’s not a random number plucked from the ether. VR is a specific airspeed that, for single-engine airplanes, must by regulation be no less than VS1, which is the stalling speed of the aircraft in a specific configuration. That makes sense. By establishing a rotation speed that is at or above the stalling speed in a specific configuration, you can enhance the safety of flight. If the pilot doesn’t even try to get airborne until the aircraft is moving at a speed that will allow it to fly effectively, the likelihood of an inadvertent stall on takeoff is reduced considerably. Imagine how many very short, overly exciting flights might have been turned into much longer, much less dangerous
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VS. According to the FAA, VS is the stalling speed, or the minimum steady flight speed at which the airplane is controllable. One knot higher and you’re flying. One knot lower and you’re not. Ironically, it could be argued that the key to understanding VS isn’t the airspeed at all. It is what the airspeed represents, for it is at VS that your airplane will be at the critical angle of attack. That’s assuming you

time. They do it in training; they do it when they’re working on proficiency in the airplane; and they stall it inches above the ground to drop it smoothly onto the runway whenever they perform a good landing. With the stall horn blaring, a slight buffet felt through the controls, and a sudden settling of the airplane back to earth, a good pilot can violate VS on every flight and still be considered to be a good pilot. The key that separates a good stall from a bad stall is where we violate VS, and whether we do it by choice or by chance.

VNO

THE AIRSPEED indicator gives some V speed clues, but not all. Flap, normal flight range, stall speed, and the ominous red line are present, but maneuvering and rotation speeds will never be shown.

are in straight-and-level flight, of course. VS is the point at which the air flowing over the upper surface of the wing can no longer flow smoothly to the trailing edge. It eddies and burbles and leaves the surface to wander aimlessly in the surrounding atmosphere. Lift is lost, drag increases, the nose drops, and a stall ensues. Violating VS isn’t necessarily a bad thing. Pilots stall their airplanes all the

isn’t a flight student in the United States who hasn’t had the basics VS drilled into his head about the importance of VA. It’s often called the aircraft’s design maneuvering speed, and that has caused many a pilot to misunderstand what VA really is, and how it can be unintentionally violated—with potentially catastrophic results. The first oddity about VA is that it changes with the weight of the aircraft. VFE As the airplane gets lighter, VA gets lower. That quirk of the various sciences affecting aircraft in flight means that VA represents a range of airspeeds for any given airplane. If the airplane is loaded to its maximum weight, its design maneuvering speed is higher. As the fuel burns off and a passenger gets out at an intermediate stop, taking a suitcase with him, the airplane gets lighter, which results in VA becoming a lower speed. Knowing what VA really is and sticking to it is tremendously important to anyone who plans to be safe in the air. In an unstable air mass where air currents cause a bumpy ride, those bumps are imposing momentary increases in load factor on the airplane. If you’re at or below VA, the airplane will stall before the structure is damaged by excessive loads. But if your airspeed sneaks above

» V . That brings us to V . There
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Flight Training - July 2012

Table of Contents for the Digital Edition of Flight Training - July 2012