Definitions - P-8670074

T-39 FLIGHT PREPARATION

STUDENT GUIDE

(7) VMCG: The speed at which the aircraft can be controlled on the ground with a failed

engine and by use of aerodynamic controls alone. The speed is based on the failed

engine windmilling, takeoff thrust on the good engine, the nosewheel off the runway, and

use of ailerons and rudder to maintain directional control within 25 feet of the desired

path.

VB: The design speed for maximum gust intensity.

(8)

VF: The design flap speed.

(9)

(10) VMO: The maximum operating limit speed.

(11) VSO: Stall speed or the minimum steady flight speed in the landing configuration.

(12) VREF: Final approach speed at the 50 feet threshold height in a normal landing

configuration.

(13) Balance Field Length: The distance within which the aircraft can either accelerate

to V1 and then stop, or accelerate to V1 and continue to a height of 35 feet with one

engine cut at V1.

(14) Critical Field Length: The distance within which the aircraft can either accelerate

to refusal speed and then stop, or accelerate to refusal speed and continue takeoff while

one engine is failed at refusal speed. All available runway will be required to get the

aircraft airborne.

(15) Second segment climb: The aircraft must be capable of maintaining a climb

gradient of at least 2.4 % (24 feet per 1,000 feet) with one engine inoperative and the

other engine at takeoff thrust.

(16) Third segment climb: May be used for level-flight acceleration at 800 feet above

the airport pressure altitude to final takeoff climb speed.

(17) Engine Pressure Ratio: This is the ratio of the turbine discharge total pressure to

compressor inlet total pressure. Turbine discharge total pressure is an average pressure

taken by four probes manifolded together immediately downstream of the turbine.

Compressor inlet total pressure is measured by two electrically heated pitot pressure

heads, one for each instrument, mounted on the leading edge of the vertical stabilizer.

(18) RCR: A measure of tire to runway friction coefficient. RCR is given as a whole

number. This value is used to define the braking characteristics for various runway

surface conditions. The reported RCR is therefore a factor in determining any

performance involving braking, such as critical engine failure speed and refusal speed.

Some airfields report runway braking characteristics in accordance with ICAO

documents, that is, "good", "medium", and "poor". In order to relate these ICAO

G-4