The idea of delivering troops by parachute first took hold in World War I, although it wouldn’t be done at the time. But between the wars, something new arose as a possibility: glider delivery.
Airspeed Horsa gliders at Pegasus Bridge, 6 June 1944.
Gliders had several advantages, at that point in time. The machines themselves were cheap and fast to build, and thus expendable, like a rifleman’s parachute in wartime. Unlike parachutes, which were prone to scattering, gliders had potential to deliver squad- and later section-sized units, intact and cohesive, into the enemy’s rear area: much less assembly required. It was believed that the pilots would need much less training than powered-plane pilots, and they could then join the fight as infantry1.
The Soviets Led the Way
As is common in weapons of war, several nations developed gliders at about the same time. But somebody had to be the absolute first, and that was the Soviets, who were also world leaders in paratroop innovation. Their first military gliders were developed in the Red Army under the brilliant and innovative Marshal Tukhachevsky, as part of a flowering of military experimentation in the USSR in the 1920s and 30s. The Soviet exercises caught the attention of the world’s militaries; the first officially-adopted military troop glider seems to have been a Russian model, the Grikhonov of 1932 (we have been unable to find an image of this aircraft).
A Gribovski G-11 glider (or replica?) maintained as a memorial to glider troops.
Antonov AN-7 design owes a lot to prewar sailplanes.
But the 1930s ended badly for the USSR’s military innovators like Tukhachevsky and almost all senior officers of the Red Army, who were accused of various crimes and executed after brief and predetermined show trials.
In World War II, the Soviets built a small number of gliders of two types, the Antonov An-7 and the Gribovski G-11 (the numbers, unlike in powered Soviet aircraft, showed the plane’s capacity in armed troops).
They never did use them in a large assault, using them instead in special operations and for partisan resupply. As in other nations, glider pilots trained in typical sailplanes before flying the trucklike cargo gliders. The cargo-carrying and particularly loading capacity of these Soviet machines was badly compromised by their design; other major powers had gliders with cavernous loading doors, but the Soviet machines seemed to have small, personnel-sized hatches only.
German Para with FG42 in front of a DFS-230. (it embiggens). Bundesarchiv photo.
The Soviets’ fellow totalitarians, the Nazis, also had a glider industry prewar, and that yielded their troop glider pilots. The glider troops came from paratroop volunteers.
The Deutsche Forschungsanstalt für Segelflug was abbreviated, for reasons that seem self-evident, to DFS. The name meant German Institute for Sailing Flight and, during the Versailles Treaty years, when German production of powered aircraft, and then, powered military aircraft, was verboten, it was home to many of Germany’s most talented aeronautical engineers.
Tasked to make a military glider, DFS did what its Soviet opposite numbers had done and scaled up a tube-and-fabric sailplane design. Numbered in a series that went back to prewar research, the cargo glider had no name: it was the DFS 230. It had no cargo door, just a very small personnel door from which the troops must exit one at a time. It couldn’t carry heavy weapons — an MG-34 or a mortar, max.
Despite its limits, several special operations were executed with the DFS 230, including the seizure of Eben Emael in 1940s Low Countries campaign and the rescue of Mussolini from Gran Sasso in 1943. By using a drag chute, it could land in very small areas.
A restored DFS fuselage arrives to be displayed at Fort Eben Emael. German para-engineers landed on top of the fort; 78 men captured a fort manned by 1100 and removed an obstacle from the 1940 blitz.
Germany also developed large cargo gliders, one a pod-and-twin-boom arrangement from Gotha and one a gigantic vehicle carrier from Messerschmitt (Me321). Later, many of the gliders were refitted with captured French aero-engines to become somewhat under-engineered cargo planes, making up a German shortfall.
The Japanese used gliders early in the war; Japanese airborne troops were a little-explored facet of their Asian blitzkrieg, and later, gliders were used both to supply cut-off islands and to land small commando forces on Allied-held airfields.
As was often the case, Japanese engineers were competitive even when Japanese industry struggled to keep pace. The late-war Kokusai Ku-7 glider (below) was as advanced as anything produced by the other powers.
Other Axis Gliders
Italy produced competitive gliders, but in very small numbers. Surviving photos show machines with clean, elegant lines, but there is scant information on them being used in World War II. And there is no information at all on gliders that may have been used by Romanian or Hungarian forces.
Western Allied Gliders
In the US and UK, special cargo and training gliders were developed. Unlike the Russian and German glider pilots, who tended to be trained in commercial sailplanes, he US quickly threw together engineless versions of light training and liaison aircraft, like the L-4 Piper Cub. Western cargo gliders had a big advantage over the Russian ones: cargo doors. For example, the tailcone and cockpit of the Airspeed Horsa both came off readily, allowing fairly heavy equipment like Jeeps, anti-tank guns, and small field pieces, to roll on and roll off. The Waco also had a hinged cockpit that swung up out of the way. Japanese and the larger German gliders were similarly equipped with opening ends, and these inspired postwar cargo planes of all nations.
Numerically, the most important glider was the WACO CG-4A. The glider could deliver a squad and its equipment, or a Jeep as seen above, or a 37mm or 57mm anti-tank gun and crew (British 2 pdr/6 pdr). The British Army, who assigned glider pilots to the Glider Pilot Regiment and expected them to fight as infantry once they landed, named their gliders with names from antiquity beginning with “H”; the WACO received the name of the Roman conqueror of southern Britain, Hadrian. It was built with scaled-up Piper Cub technology, or Fokker D-VII technology for that matter: a 4130 chromoly steel frame and glued plywood wing structure, both covered by doped cotton fabric. The cockpit had seats for side-by-side pilot and co-pilot, a luxury (or combat redundancy) most other nations’ gliders dispensed with, but was still pretty austere, and not too foreign to a Cub pilot, despite having wheels instead of sticks.
This detached WACO cockpit is in the Silent Wings Museum in the USA.
Allied gliders were made in part by aeronautical prime contractors, but wherever possible, by non-war-critical industries using industrial processes that did not impinge on war production. The Army Air Corps paid as little as a few thousand dollars, and as much as over $50,000, more than some powered aircraft, depending on the contractor. (The experienced airplane builders generally built more gliders for less money).
Not all the contractors got the hang of it right away. The following photo shows the Mayor of St. Louis and the head of the Robertson Aircraft Corporation and other luminaries about to take the first public flight of a Robertson-built glider in 1943. You can recognize the distinctive cockpit from the image above. A few minutes after this photo was taken, the glider crashed due to bad quality control — and the pilots and all these notables were killed. (The guy second from the right seems to have a bad feeling about this flight).
The glider troops — none of whom would have known about this accident, unless they came from St. Louis — had to have a very different kind of courage than paratroops, at least in US service. American glider riders were not volunteers, unlike paratroops, and they received no incentive pay, unlike paratroops, but no one could really argue that they were any less exposed to hazard — and they had even less control of the hazards than the jumpers did. Despite the grumbling, the glidermen saddled up for Sicily (where many of them were killed by trigger-happy Navy anti-aircraft gunners), Normandy (where planners routed the transports away from where the Navy was congregating), Market-Garden in Holland, and the operation that is still probably the largest airborne operation in history, the assault across the Rhine.
The next most significant glider in the West was the Airspeed Horsa. A British-made plywood machine that was larger than the CG-4A, it could also carry heavy weapons and was involved in all the same airborne operations as the WACOs were.
It was generally shipped to its departure airfield in knocked-down condition, and then assembled there:
It also was the transport craft for two signal British special operations, one a failure and one a success: Operation FRESHMAN in Norway, and the Pegasus Bridge (as it is now called) seizure on the River Orne on the left flank of the D-Day landings. Of the FRESHMAN gliders, only one had survivors, and they were promptly murdered by the Germans pursuant to Hitler’s Commando Order.
Gliders traveled by aero-tow, usually behind transports or retired/obsolete bombers.
Rather than teach glider pilots to do weight-and-balance calculations manually, special balances made of wood with items representing troops and cargo were issued by Allied air forces. The crews moved their mock-up “loads” around until the balance balanced, and if they did that, and loaded the glider the same way, the center of gravity would be in range.
Several special operations in the Far East, especially in the CBI, used gliders. They also used a glider recovery system that allowed transports to pick up gliders on the fly; this system was available in the European Theater but little used. The concept of US operations did not envision gliders being one-use aircraft, but that’s how it worked out in most cases.
The Twilight of the Gliders
The end of the gliders came about after the war. Airborne forces of all kinds are costly to train and equip, and only the world’s major powers kept them up at a high level, although there was a spurt of newly-decolonialized nations of the 50s and 60s establishing Airborne units, which they then neglected. Compared to gliders or helicopters, parachute troops were relatively cheap; they could jump from versatile cargo planes with many other uses.
The US kept qualifying troops on gliders — indeed, at one time in the late forties all airborne soldiers were expected to qualify as both parachutists and glidermen — until a training accident in 1947 was traced to fatigue failure of the wartime Waco airframe. Rather than face the bill for reinforcing the remaining gliders to make them safe again, the Army scrapped them.
The USAF briefly considered making a new glider, and went as far as ordering some prototypes of Michael Stroukoff’s designs for Chase Aircraft Company of Trenton, NJ, the XG-18A and the XG-20. Both had conventional cockpits in the nose, and opening tailgates in the rear for personnel or cargo. The XG-20 is shown here:
The Air Force decided to abandon the idea of gliders, and the Chase aircraft were modified into powered airplanes, the small XC-122 transport and the mid-sized C-123, which served until the 1980s in the USAF. Because Stroukoff designed the gliders without considering fuel tankage in the wings, the cargo planes carried their fuel in extended nacelles. (The only act of Medal of Honor heroism to be photographed in Vietnam was by a C-123 pilot who landed to recover an Air Force Combat Control crew who had been mistakenly landed on an overrun Special Forces camp at Kham Duc. Not many trash hauler pilots earn Medals of Honor, but that guy sure did).
Last of the Cargo Gliders: Yakovlev Yak-14, 1948. Conventional design, tricycle gear, opening nose and tail. Source: Air Enthusiast (May ’72) via AviaDejaVu.Ru
The glider was never a wonderful weapon — it was always a brilliant improvisation. Besides, helicopters were starting to show promise. Like a glider, a copter could land a group of men together. And like a glider, copters could carry significant weight of equipment.
The Soviets, who started first, are thought to have ended last, keeping some military gliders as late as 1960 to 1965. The last military glider in service, then, was likely the postwar Yak-14, shown here under tow by an Ilyushin Il-14 transport :
Swan song: Yak-14 of the Czechoslovak People’s Army 22nd Airborne Brigade, late 50s.
By the 1960s, the USSR had really mastered the aerial delivery of artillery and even light armored vehicles by parachute, and had a vast array of cargo aircraft, including an immense war reserve of Aeroflot planes whose crews were reserve officers and airplanes “reservists” themselves.
The Future of Gliders
It is not impossible that a glider will come back as a special operations delivery system, but one with a twist. Several firms and researchers have been examining the possibility of suborbital space insertion as a way to deliver SOF into denied areas at unprecedented speeds, with potentially global reach in 45 minutes to 2 hours of flight time. The problem is how to use such a fast glider against a sophisticated enemy — without him thinking you’re nuking him, and nuking you back preemptively?