Climb-Out and Shutdown Procedures
Self-launching gliders have powerplant limitations, as well as aircraft performance and handling limitations. Powerplant limitations include engine and oil temperatures, engine rpm limits, and other engine/aircraft limitations listed in the GFM/POH.
The GFM or POH provides useful information about recommended power settings and target airspeed for best angle of climb, best rate of climb, best cooling performance climb, and cruise performance while in powered flight. If full throttle operation is time limited to reduce engine wear, the GFM/POH describes the recommended operating procedures. Aircraft performance includes weight and balance limits, minimum and maximum front seat weight restrictions, maximum permitted airspeed with engine extended, maximum airspeed to extend or retract the engine, flap operating airspeed range, air brake operating airspeed range, maneuvering speed, rough air speed limitations, and never-exceed speed.
The engine heats up considerably during takeoff and climb, so cooling system mismanagement can lead to dangerously high temperatures in a short time. An overheated engine cannot supply full power, meaning climb performance is reduced. Extended overheating can cause an inflight fire. To minimize the chances of engine damage or fire, monitor engine temperatures carefully during high power operations, observing engine operating limitations described in the GFM/POH.
Many self-launching gliders have a time limitation on full throttle operation to prevent overheating and premature engine wear. If the self-launching glider is equipped with cowl flaps for cooling, make certain the cowl flaps are set properly for high power operations. In some self-launching gliders, operating at full power with cowl flaps closed can result in overheating and damage to the engine in as little as 2 minutes. If abnormally high engine system temperatures are encountered, follow the procedures described in the GFM/ POH. Typically, these require reduced power with higher airspeed to enhance engine cooling. Cowl flap instructions may be provided as well. If these measures are ineffective in reducing high temperatures, the safest course of action may be to shut down the engine and make a precautionary landing. A safe landing, whether on or off the airport, is always preferable to an inflight fire.
Handling limitations for a given self-launching glider may be quite subtle and may include minimum controllable airspeed with power on, minimum controllable airspeed with power off, and other limitations described in the GFM/POH. Self-launching gliders come in many configurations. Those with a top-mounted retractable engine and/or propeller have a thrust line that is quite distant from the longitudinal axis of the glider. The result is that significant changes of power settings tend to cause substantial pitch attitude changes. For instance, full power setting in these self-launching gliders introduces a nose-down pitching moment because the engine thrust line is high above the longitudinal axis of the glider. To counteract this pitching moment, the pilot holds the control stick back pressure and trim. If power is quickly reduced from full power to idle power while holding an control up stick force, the glider tends to pitch up with the power reduction. This nose-pitching moment may be vigorous enough to induce aircraft stall. Smooth and coordinated management of power and flight control provides the safest procedure under these conditions.
During climb-out, the pilot should hold a pitch attitude that results in climbing out at the desired airspeed, adjusting elevator trim as necessary. As previously stated, climbs in self-launching gliders are best managed with smooth control inputs; when power changes are necessary, make smooth and gradual throttle adjustments.
When climbing under power, most self-launching gliders exhibit a left or right turning tendency (depending on whether the propeller is turning clockwise or counterclockwise) due to P-factor. P-factor is caused by the uneven distribution of thrust caused by the difference in the angle of attack (AOA) of the ascending propeller blade and the descending propeller blade. Use the rudder to counteract P-factor during climbs with power. [Figure 7-25]
Turns are accomplished with a shallow bank angle because steep banks result in a greatly reduced rate of climb. As with all turns, properly coordinated aileron and rudder movement result in a more efficient flight and faster climb rate. The pilot should scan for other aircraft traffic before making any turn. Detailed engine shutdown procedures are described in the GFM/POH. A guide to shutdown procedures is described below, but the GFM/POH is the authoritative source for any self-launching glider.
Engines reach high operating temperatures during extended high-power operations. To reduce or eliminate shock cooling caused by a sudden reduction of engine power setting, reduce power slowly. Shock cooling is generally considered to be the outside components of an engine cooling much faster than the truly hot parts inside the engine not directly exposed to cooling airflow. This shock cooling allows the external parts to cool faster and shrink more than the interior components resulting in binding and scuffing of moving parts such as piston rings and valves.
To reduce the possibility of inflight fire, the manufacturer provides engine cool-down procedures for reducing engine system temperatures prior to shutdown. Reducing throttle setting allows the engine to begin a gradual cool down. The GFM/POH may also instruct the pilot to adjust propeller pitch at this time. Lowering the nose to increase airspeed provides faster flow of cooling air to the engine cooling system. Several minutes of reduced throttle and increased cooling airflow are enough to allow the engine to be shut down.
If the engine is retractable, additional time after engine shutdown may be necessary to reduce engine temperature to acceptable limits prior to retracting and stowing the engine in the fuselage. Consult the GFM/POH for details. [Figure 7-22]
Retractable-engine self-launching gliders are aerodynamically more efficient when the engine is stowed, but produce high drag when the engine is extended and not providing thrust. Stowing the engine is critical to efficient soaring flight. Prior to stowing, the propeller must be aligned with the longitudinal axis of the glider, so the propeller blades do not interfere with the engine bay doors.
Since the engine/propeller installation in these gliders is aft of the pilot’s head, these gliders usually have a mirror, enabling the pilot to perform a visual propeller alignment check prior to stowing the engine/propeller pod. Detailed instructions for stowing the engine and propeller are found in the GFM/POH for the particular glider. If a malfunction occurs during engine shutdown and stowage, the pilot cannot count on being able to get the engine restarted. The pilot should have a landing area within power-off gliding distance in anticipation of this eventuality.
Some self-launching gliders use a nose-mounted engine/ propeller installation that resembles the typical installation found on single-engine airplanes. In these self-launching gliders, the shutdown procedure usually consists of operating the engine for a short time at reduced power to cool the engine down to acceptable shutdown temperature. After shutdown, the cowl flaps (if installed) should be closed to reduce drag and increase gliding efficiency. The manufacturer may recommend a time interval between engine shutdown and cowl flap closure to prevent excess temperatures from developing in the confined, tightly cowled engine compartment. These temperatures may not be harmful to the engine itself, but may degrade the structures around the engine, such as composite engine mounts or installed electrical components. Excess engine heat may result in fuel vapor lock.
If the propeller blade pitch can be controlled by the pilot while in flight, the propeller is usually set to coarse pitch. Some installations have a propeller feathering system that reduces propeller drag to a minimum for use during nonpowered flight. Some self-launching gliders require the pilot to set the propeller to coarse pitch prior to engine shutdown. Other self-launching gliders require the pilot to shut down the engine first and then adjust propeller blade pitch to coarse pitch or setting to a feathered position. As always, pilots must follow the recommended shutdown procedures described in their GFM/POH.
Common errors during climb-out and shutdown procedures include:
- Failure to follow manufacturer’s recommended procedure for engine shutdown, feathering, and stowing (if applicable).
- Failure to maintain positive aircraft control while performing engine shutdown procedures.
- Failure to follow proper engine extension and restart procedures.
If the self-launching glider is to land under power, the pilot should perform the engine restart procedures at an altitude that allows time to reconfigure. The pilot should follow the manufacturer’s recommended engine start checklist. Once the engine is started, the pilot should allow time for it to warm up. After the engine is started, the pilot should ensure that all systems necessary for landing are operational, such as the electrical system and landing gear.
Caution: Follow the manufacturer’s recommended engine extension and restart procedures or a loss of situational awareness could result in attempting a landing with the glider a high drag configuration. The pilot of a sustainer or self-launching glider should plan for the engines to fail to start and not have sufficient power to retract the engine and exhibit a much higher drag coefficient. Should the engine not start and retract, a glider pilot should have an alternate landing area available with the decreased performance available in the higher drag configuration.
The pilot should fly the traffic pattern to land into the wind and plan the approach path to avoid all obstacles. The landing area should be of sufficient length to allow for touchdown and roll-out within the performance limitations of the particular self-launching glider. The pilot should also take into consideration any crosswind conditions and the landing surface. After touchdown, the pilot should maintain direction control and slow the self-launching glider to clear the landing area. The after-landing checklist should be completed when appropriate.
Common errors during landing include:
- Poor judgment of approach path.
- Improper use of flaps, spoilers, and/or dive brakes.
- Improper approach and landing speed.
- Improper crosswind correction.
- Improper technique during flare and touchdown.
- Poor directional control after landing.
- Improper use of brakes.
- Failure to use the appropriate checklist.
- Failure to use proper radio communication procedures.