CG-4A Glider Pilot Training Manual
Prepared for Headquarters AFF. March 1945.
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Pilot manual introduction: Your Job
You have an important job-that of carrying airborne troops and equipment behind enemy lines, over unfamiliar territory, and into strange landing areas. It's a big responsibility, and demands your best.
Glider flying calls for no techniques unfamiliar to the power pilot, but it does require a new emphasis on certain old techniques. To he a competent glider pilot, for instance, you must be a specialist in landings. The success of any glider mission depends on your ability to land your passengers and cargo safely at a given point and time. There are no reserves in an airborne invasion. If you fail to deliver your load at the right spot, you may turn victory into failure and cause a needless sacrifice of life.
Contrary to popular belief, the glider is not limited to a single mission. Neither are you. The ground combat training you receive is to enable you to defend yourself until you can be evacuated for another mission.
Your primary responsibility is flying. Your secondary duty, since it is not always feasible to evacuate you immediately upon landing, is to fight as a ground soldier with the airborne troops you have transported. Only your primary duty-that of flying-is considered in this manual.
Glider flying under conditions encountered in combat demands all the knowledge and skill you can acquire. There are no nearby towns to illuminate the sky at night and no welcome airfields on which to land; high trees may block your approach, and rock-strewn, stumpstudded fields may endanger your landing. The additional hazard of ground fire further complicates the task.
Your training conditions you to overcome natural instincts under such circumstances, and follow correct procedures designed to get you down safely. In training you fly under a merciless sun in a monotonous pattern. You fly at night under adverse conditions. If it seems unnecessary at the time, remember that such training prepares you for combat .. Take advantage of it.
The CG-4A glider is a IS-place, high-wing cabin monoplane having a fabric-covered, steel-tube fuselage, wood wing with plywood and fabric covering, fixed-type landing gear and nose skids, and hydraulic brakes.
Dual wheel controls, side by side; adjustable rudder pedals; toe brakes on the pilot's side only; trim tab controls, and dual lever-operated spoiler controls.
The location of the pitot-static tube causes an error in readings for both the airspeed indicator and the altimeter. The reason for this error is that the pitot-static head is in a lowpressure, high-velocity area in the -airstream which sweeps over the nose section. The high velocity of air in this area accounts for an exaggerated reading of 128 mph in indicated airspeed (IAS) when calibrated airspeed (CAS) is 120 mph.
As your airspeed drops, the error of reading on your airspeed indicator increases slightly. The error throughout the range of glide speeds (60 to 85 mph IAS) averages 10 mph.
Indicated airspeeds referred to in this manual, therefore, are only approximations, and are 'so marked. They are given in round numbers, and are followed in parentheses by calibrated ai~eeds.
Because of this instrument error, learn to rely on the feel and sound of your glider, especially when flying close to the stall speed.
The location of the pitot-static tube also causes an error in the reading of the altimeter. The lower air pressure in the area of the static opening causes the altimeter-when CAS is 120 mph-to indicate an altitude 200 feet higher than you are actually flying.
In making a tactical approach two factors must be given first consideration:
- For the shortest possible landing run (approaching over an obstacle), you must approach and land at the lowest safe flying speed. The landing must be simply a continuation of the approach, without a flare-out, or floating period.
- For accuracy in the approach to the landing spot, you must fly at that airspeed which allows you a maximum of control of the glide angle through slight changes in airspeed.
In considering the first factor, the lowest airspeed at which you can safely make the approach is that which is barely above the stall. However, at this speed you have the least control of the glider. Any attempt to increase the airspeed by lowering the nose results in a partial stalling of the wing. A loss of between 50 and 100 feet of altitude, depending upon the gross weight of the glider, should, in this event, be anticipated. In addition, a turn attempted at this speed results in an immediate stall, and a falling away on one wing, since the ship is already too close to the stall speed to permit any increase in wingloading.
Normal Glide Speed
To determine how much above stalling speed to fly, consider the normal glide. The normal glide speed is that which results in covering the greatest distance for a given loss of altitude (assuming no-wind conditions).
The normal glide is the most efficient airspeed at which the glider can be flown. For the CG-4A, at its designed gross weight, it is approximately 85 mph lAS (72.6 mph CAS).
Since the glider, at any airspeed above the normal glide, is losing altitude at a greater than normal rate, such airspeeds must be considered as diving rather than gliding speeds.
In following the standard approach patterns there is no advantage in flying the maximum distance over the ground. In planning your ap-proach, figure on a glide much steeper, and therefore slower, than the normal glide.
Tactical Glide Speed
The glide speed which is standard for combat gliders is called the tactical glide. It is a speed approximately halfway between the stall and normal glide speeds.
Since the approximate figures for the stall and the normal glide speeds (calculated for the CG-4A at 7500 lbs. gross) are 60 and 85 mph lAS, respectively, the tactical glide speed is about 70 mph.
In playing the glide speed to obtain the desired rate of descent, you need vary your airspeed little more than 10 mph above or below the tactical glide to cover the full range of glide angles.
The use of the tactical glide gives maximum control over your glide angle, as follows:
- To steepen your glide path, raise the nose a few degrees, decreasing the airspeed.
- To flatten the glide path, lower the nose, increasing the airspeed.
In playing the glide speed to control the glide angle, the desired results do not occur im~ mediately. For example, when you raise the nose of your glider to decrease the airspeed. and so steepen the glide angle, the first result is an abrupt leveling off, or even climbing, as the excess airspeed is dissipated.
Likewise, when you lower the nose to increase the airspeed and so lengthen the glide, the most noticeable immediate effect is a loss in altitude. These reactions are confusing and, unless anticipated, may make you think you have applied the wrong technique. When in danger of undershooting and the trees look close, you need plenty of will power and great faith in your own knowledge of aerodynamics to make the only correction possible and lower your glider's nose.
The CG-4A was not designed as - a sailplane.
It is simply a cargo-carrying airplane without engines, and falls in the same category as other troop-carrier type aircraft. The CG-4A reacts to the same aerodyhamic forces with the same
contrels and in the same manner as the airplane. Any heavier-than-air pilot can step from the cockpit of one to the other and feel at home at the flight controls after normal transition training,
SPEED AND LOAD LIMITATIONS
- Maximum designed speed on tow or in free flight: 150 mph CAS
- Maximum designed gross weight (normal load): 7500 Ibs.
- Maximum emergency gross weight (not to be exceeded): 9000 Ibs.
- Minimum load: Pilot, copilot, and 600 Ibs. of ballast (300 lbs. behind each cockpit seat)
Gross Weight Maximum Permissible CAS Maximum Permissible lAS
7500 150 mph 158 mph
8000 143 151
8500 135 143
9000 128 136
Stall Speed: 49 mph Approx. 60 mph
With designed load (7500 Ibs.)
Tactical Glide Speed: 60 mph Approx. 70 mph
(Landing speed) with designed load
Normal Glide Speed: 72.6 mph Approx. 85 mph
with designed load
Landing Run: (Room required for normal 3-point landing) 600 to 800 feet.
(Ground run can be greatly shortened by using emergency stop.)
Rate of Descent (Designed Load): Approximately 400 feet per minute
(at tactical glide speed).