NASA's Amazing Gliding Gemini Capsules
On August 7, 1964, Charles Hetzel took to the skies in a winged Gemini spacecraft. It was a test flight for a new landing system, the Rogallo paraglider wing, that NASA had been trying to work into its Gemini spacecraft. Despite years of work and a series of flight tests, the program failed to match the success of the agency’s lunar program.
The Rogallo wing, named for its inventor Francis Rogallo, was a two lobed sail designed to attach over the Gemini spacecraft and give the vehicle lift. The idea was to make splashdowns obsolete; the Rogallo wing could, in theory, give the Gemini spacecraft enough lift and controllability that an astronaut could pilot it to a runway landing.
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In 1961, runway landings were one of the three program goals for Gemini. Development of the system began in 1962 with full scale manned flights starting two and a half years later in August of 1964.
The test vehicle, built by North American Aviation, was called the Gemini Test Tow Vehicle or TTV. Test flights, like so many experimental vehicle programs, began with captive flights. The TTV was attached to a helicopter by a tow rope, carried up to altitude, then the left to glide down to a smooth landing still attached to a copter. Successful captive flights paved the way for free flights.
Free glide flights started off the same way as captive flights with a helicopter towing the TTV to altitude. Then, the towline was cut. The unpowered TTV was left to glide under its own aerodynamics to a smooth landing. North American pilot Hetzel was the first to sit inside the TTV and pilot it to a landing; the contractor would make sure the system was safe before handing it over to NASA.
Hetzel had no problems during the tow to altitude. It was when he severed the tow line that things turned sour. Almost immediately, the TTV started to fall rather than glide, spinning violently as it sped towards the ground. Out of options, Hetzel managed to eject before the TTV smashed into the hard, dry lakebed at Edwards Air Force Base. The pilot sustained a broken rib from the force of ejection; the TTV needed to be rebuilt and rethought before another pilot could get behind the controls.
North American ran a series of radio-controlled half- and full-scale landings over the next five months. It also recruited a new pilot, Don McCusker, to be fly the next TTV tests.
On Dec. 19 that year, McCusker climbed in the rebuilt TTV. He was towed up to test altitude safely and severed the tow line.
Things looked good at first as McCusker managed five minutes of controlled gliding before coming in for a landing. He managed a landing, but it was hard. He was traveling 30 feet per second when he hit the lakebed; the landing was considered a barely-controlled crash. The TTV wasn’t built to sustain forces that high and McCusker ended up in hospital from the shock.
Again, the TTV was refurbished and a third pilot filled out the ranks of those who would fly the spacecraft: Jack Swigert. Swigert successfully piloted the TTV to a smooth runway landing early in 1965, then used the experience to bolster his chances at joining NASA astronaut corps. He did in 1966, flying as Command Module Pilot on Apollo 13.
Unfortunately, by the time gliding Gemini landings were perfected with the TTV it was too late for the Rogallo wing. After Gemini 3 flew in March 1965 NASA scrapped the runway landing system from the program and committed to splashdowns for every Gemini and Apollo mission. The TTV and to a large extent the Rogallo wing, has been left as little more than a footnote in NASA’s history.
Image: The Gemini-paraglider configuration. Credit: NASA