air force glider retrieval system

8/9/2019 Air Force Glider Retrieval System

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WWII u.s. Army Air Force Glider Aerial Retrieval System

Compiled by Leon B. Spencer, former WWIIGlider Pilot

The architects of the U.S. Army Air Forces glider program determined inthe spring 1942 that the large troop and cargo canying gliders under develop-ment were simply too expensive to be abandoned after one combat mission.The cheapest unit price for a IS-place CG-4A was $15,580, while some compa-nies charged much more. The fields and pastures in which gliders landed wereusually too small and the terrain too uneven for a plane to land and retrieve thegliders. Another means of recovery had to be found. To find an answer to theirproblem the Air Force turned to Richard C. duPont, a 1930s national glidersoaring champion and the president of All American Aviation of Wilmington,Delaware. Several years earlier, DuPont's company had developed an aerial re-trieval system to pick up U.S. Postal Department mail pouches from the groundby an aircraft on the fly, and had demonstrated to U.S. Air Crops officials atWright Field, Ohio, on 18 July and 22-28 September 1941 that aerial retrievalof gliders was feasible.


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USAAF GliderAerial Retrieval System. Cont'd Page 2

fuselage and then to a hook at the end of the boom. The system functionedmuch like a fishing rod and reel. The pickup airplane would fly low (approxi-mately 20 feet above the ground) over the pickup station and hook a nylon loopstretched between two poles approximately 12 feet above the ground. Just asthe hook snagged the loop the pilot would pour on the power and climb away ata fairly steep angle, dragging the mailbag behind the plane on the cable. At themoment the hook made contact the winch would feed out cable to absorb theinertial energy of the pouch weight. The operator would then retrieve the pouchby rewinding the steel cable.

The aerial retrieval demonstrations conducted by AM July and Septem-ber 1941 used the Model AAS-4 pickup winch installed in a company StinsonSR-10C high-wing monoplane. The Stinson successfully snatched a 500 poundgross weight "Midwest Utility" glider containing a weighted pilot dummy fromthe ground. Following the demonstrations, AM issued a report proposing thatthey could build a system to pick up heavier gliders.During further tests in 1942, All American Aviation used the Stinson SR-

10C to successfully snatch a two-place, Schweizer XTG-3 military training


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USAAF Glider Aerial Retrieval System, Cont'd P.i!ge3

Initial flight testing of the M-80 system was conducted at AAA's DuPontAirport in Wilmington, Delaware, in the first half of 1943, but subsequent pri-mary testing was switched to CCAAF. An 1821 foot nylon tow rope, 15/16inches in diameter, was initially used for the Waco CG-4A tests. One end of thetow rope was connected to the nose of the glider, while the other end was con-nected to a closed loop of nylon rope, 80 feet in circumference, which wasdraped over the top of two 12 foot stanchions spaced 20 feet apart and posi-tioned ahead of and slightly to the right of the glider.

The use of tow ropes made of nylon fiber developed by the E. I. DuPontCompany greatly enhanced glider "snatch pickups." This fiber, when woveninto a rope, was elastic. It would stretch 25% to 30% of its length and thus ab-sorb much of the shock as the glider became airbome. The rope would then re-tum to its original length. Because of this characteristic, the average accelera-tion for pickup was only 7/10 of one G, which according to AAF Manual No. 5-17, lasted about 6%2 seconds. This is significant if you consider that pilotscatapulted from an aircraft carrier experience 2% G's. The glider would usuallybecome airbome in no more than 200 feet.

Twin-engined Douglas C-47 transports were the primary aircraft used to


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tor's function was to properly set the pickup drum clutch snubbing adjustment,which was based on the glider's weight and the aircraft's proposed speed at theinstant of the cable hook/ glider rope loop engagement. The drum manufac-turer (General Aviation) provided a chart with recommended snubber settingsfor various glider weights/aircraft contact speeds, etc. The shock of the initialcontact with the nylon rope was the critical moment that placed the greateststress on the flexible steel cable. At the very instant of "snatch" the winch op-erator's judgment received its most critical test. A misjudgment could result ina broken cable and possible severe injury to the operator or damage to the air-craft, or both.

When retrieving a glider the tow plane approached the pick-up station ata 45 degree angle about twenty feet above the terrain at 130 to 145 miles perhour IAS, depending on the gross weight of the glider. At the moment the towrope was snagged by the aircraft's trailing hook the winch drum began to feedout cable rapidly, then more slowly as the brake took effect. Some of the initialshock was absorbed by the unwinding cable and the elasticity of the nylon towrope. In a matter of about seven seconds3 the glider would accelerate from 0 to120 miles per hour lAS and would become airborne in as little as sixty feet. Atthe same time the extra weight of the glider slowed the tow plane to about 105


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Once the aerial retrieval system became operational glider pilot studentsat the Glider Crew Training Center at Laurinburg-Maxton Army Air Base wererequired to participate in at least one snatch pickup as fIrst pilot, and one ascopilot. As the need for gliders became more acute at glider pilot training basesit was not uncommon for CG-4As to be snatched rather than shipped from themanufacturers' plants. This was frequently the case at the Ford Plant at IronMountain, Michigan; the Gibson Refrigerator Plant at Greenvi11e, Michigan; andthe Waco Plant at Troy, Ohio.

Glider snatch pick-up was employed by the USAAF in the European andChina-Burma-India (CBI) theaters during World War II. Pick-up teams re-trieved downed gliders from the battlefIelds of France, Burma, Holland andGermany. Extant records note that thirteen gliders were retrieved from Nor-mandy, France, two hundred fIfty-six4 (256) from Holland following OperationMarket-Garden, and one hundred forty-eight (148) from Germany following Op-eration Varsity.

On 21 June 1944, Captain Roy Sousley and ten other glider pilots fromthe 437th Troop Carrier Group were sent to Normandy to begin preparations for


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An Army nurse from the 816th Medical Evacuation Squadron, Lieutenant SuellaV. Barnard (or Bemard), volunteered to accompany and care for the woundedenroute. She became the only nurse to participate in a glider combat missionduring WWII.A second high profile glider mission was carried out following the crashof a C-47 in Hidden Valley, New Guinea, on 13 May 1945. Two paratroopermedics jumped at the crash site five days later to care for the injured survivors,two soldiers and a WAC corporal while rescue plans were formulated. It was

decided that the safest method of rescue was to land a CG-4A glider at site tenmiles below the crash site and retrieve it by snatch pickup. On 20 May, Cap-tain Cecil E. Walter, Jr. and eight additional paratroopers jumped below thesurvivor's campsite to locate and clear a site for the glider to land. It took threetrips to extract the survivors and the rescue team from the valley. This re-markable rescue mission is fully described in Colonel Edward T. Imparato'sbook, "Rescue from Shangri-La," published in 1997 by Tumer Publishing Com-pany of Paducah, Kentucky.

Once the retrieval of a single glider was perfected experiments began at


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USAAF Glider Aerial Retrieval Svstem, Cant'd Page 6

An Army nurse from the 816th Medical Evacuation Squadron, Lieutenant SuellaV. Barnard (or Bemard), volunteered to accompany and care for the woundedenroute. She became the only nurse to participate in a glider combat missionduring WWII.A second high profile glider mission was carried out following the crash

of a C-47 in Hidden Valley, New Guinea, on 13 May 1945. Two paratroopermedics jumped at the crash site five days later to care for the injured survivors,two soldiers and a WAC corporal while rescue plans were formulated. It wasdecided that the safest method of rescue was to land a CG-4A glider at site tenmiles below the crash site and retrieve it by snatch pickup. On 20 May, Cap-tain Cecil E. Walter, Jr. and eight additional paratroopers jumped below thesurvivor's campsite to locate and clear a site for the glider to land. It took threetrips to extract the survivors and the rescue team from the valley. This re-markable rescue mission is fully described in Colonel Edward T. Imparato'sbook, "Rescue from Shangri-La," published in 1997 by Tumer Publishing Com-pany of Paducah, Kentucky.

Once the retrieval of a single glider was perfected experiments began at


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The C-47 for the first test was flown by Lt. Lee Jett, with Louie Wintersas crew chief, and other CCAAF enlisted men handling the winch and associ-ated operations. Lt. John Bryant piloted the first glider snatched, and Lt. Jo-seph Mollinary piloting the second glider.See Attachments A through F for a pictorial view of the USAAF Glider Ae-rial Retrieval System.

Note:1 - The length of the tow rope was subsequently increased to 225 feet.2 -AAF Manual No. 50-17, "Pilot Training Manual for the CG-4A Glider," Page44, notes that the winch drum could accommodate 1,057 feet of 5/8" steel ca-ble.3 - Some say as little as 3 seconds, while others say about 6 seconds. AAFManual No. 50-17 shows about 6% seconds.


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