How Does a Glider Takeoff?
Updated: Mar 16
How many ways are there to launch a glider? We can think of at least ten!
Gliders are well-known for being (mostly) unpowered. So, without an engine how does a pilot get from dreaming of being airborne while on the ground to actually soaring quietly with the birds - taking advantage of nature’s free lift elevators? We scoured the history books and came up with at least ten ways that gliders can use to defeat gravity and make the way skyward. Take a look at the list below and imagine what it must feel like to experience each method. We admit not all of the methods are commonplace today, but they have been successfully used at some time in the past. Which do you think would be your favorite?
Gravity Launch: Perhaps the oldest way of sending a glider into the air (think Da Vinci, Lilienthal, Wright Brothers). Essentially, the craft is pushed over a precipice or allowed to roll down a decline until sufficient lift is attained to take flight. This method is still used today; gliders roll down a hill and try to find ridge lift to remain airborne after takeoff.
Bungee Launch: This method is also used today. A glider is situated near the edge of a cliff and the pilot applies full brakes. Meanwhile, the team of linemen stretch the bungee line taut by grabbing two ends of the line and walking away from the nose of the glider at about 45-degree angles. Imagine an old slingshot with the rubber band attached to two posts and the projectile being held in place in the center of the band. The glider is the projectile and the linemen represent the posts in the bungee launch. Once the linemen have pulled the bungee to the appropriate tension, the glider pilot releases the brakes and is sent flying…literally!
Aero Tow: The aero tow is one of the most common methods of getting a glider into the air. It is also beneficial in that the tow plane can take the glider to a predetermined altitude and location. Generally speaking, the glider is connected to the tow plane by a 200–300-foot rope. The tow plane then accelerates down the runway while dragging the glider in its path. Most often, the glider will lift off the surface before the tow plane and stay in ground effect until the two aircraft begin to climb together. This is very much a ballet between the two aircraft and the glider pilot must remain in position behind the tow plane.
Auto Tow: The glider is connected to the vehicle by a long tow cable that is also fitted with a drogue chute (tiny parachute). The car or truck accelerates which causes the glider to gain speed and begin a rather steep climb compared to other launch methods. When the pilot releases the line, the drogue chute slows the descent of the cable to prevent injury or damage to people and property below the flight path. A disadvantage to this method is the limited altitude and distance from the launch site that is achieved. In the absence of favorable lift conditions, auto tow launches may be stuck flying close to the departure point.
Winch: This method uses an engine fitted with a large pulley and cable system. The line can be 3000 feet long or more and is fitted with a drogue chute to slow the descent of the cable after the glider pilot releases at the top of the climb. This is one of the quickest ways for a glider to get into the air with climb rates rivaling commercial jets.
Snatch: During WWII, Allied Forces used gliders extensively in combat operations. This was before the helicopter was available for dropping supplies and troops on a specific spot. The mission to get soldiers to battlefields and forward operating areas was accomplished with troop transport gliders; perhaps the most well-known being the Waco CG-4 which could carry two pilots and 13 troops with their gear. While many gliders were “crash landed” onto the battlefield or otherwise destroyed, many of them were retrieved for re-use. One method of retrieval was the snatch.
The idea behind the snatch was to set up two posts, similar to goal posts, and string a line across the two of them. Sitting behind the posts would be the glider with its pilots at the controls and the slack towline attached to the nose of the glider. A tow plane, most likely a C-47 (DC-3) would make a very low pass between the two posts with a tail hook extended to grab the raised line. If successful, the hook would catch the towline and very quickly take up any slack, jerking the glider and crew quickly into the air within seconds. The tow plane crew would then pull in the slack line with a pulley system onboard. The tail hook would be stowed and the glider would take its position behind the tow plane like any other flight.
Self-Launch: Usually when one thinks of gliders, they think engineless flight. Well, there are some designs that have onboard engines with small retractable engines (jet and propeller-driven) behind the cockpit or foldable propellers on the nose that self-stow when the engine isn’t running in order to reduce drag and increase glide efficiency.
There are many current examples of motor gliders. Some require an aero tow or winch launch to get them airborne and then they use "sustainer" motors to stay aloft for longer periods of time. Other powered gliders are fully capable of taking off and getting to a safe altitude before the pilot stows the engine or stops relying on its power.
Drop from Aircraft: Are you familiar with Virgin Galactic and their commercialization of space travel? Well, the current vehicle is named Spaceshiptwo (SS2) and it is essentially a glider with a rocket motor that is carried aloft by a mothership. Once at altitude (something like 40,000 or 50,000 feet above sea level), the SS2 is released from the cradle and fires its rocket to get above the Karman Line. After several phases of flight, the SS2 becomes a glider and makes its way back to earth. During flight testing, the aircraft was often carried aloft, released, and glided down to the base airport without ever firing the onboard rocket.
Rocket Launched: Think Nasa Space Shuttle here. The shuttle was, after all, a very special glider. In this example, the craft was attached to a series of booster rockets that would take it into orbit. The shuttle itself was fitted with rocket engines, too, that were used during launch and during its time in space, but they were not used after reentry; it was a glider at that point and relied on expert energy management to make it back to Edwards.
Other examples of rocket-powered gliders were seen during WWII. The Messerschmitt 163 Komet was a successful design that used rocket propulsion to takeoff and remain airborne, then become a glider on the way back to base.
Boat Tow: You may not believe this but after Charles Lindbergh made his historic Atlantic crossing in 1927 there was a boon in aviation enthusiasm. Many people wanted to be pilots and many companies were eager to sell their designs to the public. One of those unique ideas was the Peel Glider Boat. The PZ-1 was a motor-less biplane with a boat-like hull. A powered boat would attach a line and the glider would attach the other end of the line in bridle fashion to two points on either side of the cockpit.
Catapult: A very fascinating story about gliders and catapults comes from WWII. The Colditz (Castle) Cock was a glider built by British POW’s being held captive in Germany. The glider was designed and built inside the upper levels of the castle and kept behind a false wall. The launch method was a gravity assisted catapult; a cement-filled bathtub would be dropped to the ground in order to accelerate the glider down a very short track near the roof of the castle. While the actual Colditz glider was never used for escape, the launch method remains valid and plausible.