In a previous post, I looked at the Rogallo paraglider wing landing system and its failed development as part of NASA’s Gemini program. I also mentioned that the landing system didn’t disappear right away. After its cancellation from Gemini, NASA attempted to salvage its research and incorporate the landing system in Apollo and its follow-up programs. The US Air Force also expressed interest in including the Rogallo wing into its own space program. Regardless of the extra attention, it would seem that the paraglider was doomed to never leave the ground. (Left, a model Gemini capsule with Rogallo wing in a wind tunnel test. 1961.)
In the interest of offering a complete picture, I will briefly recap the paraglider’s developmental history before offering a brief history of the system’s life after its cancellation from Gemini.
The Rogallo paraglider wing was first introduced in 1960 as a possible landing system for the Mercury program, but it was passed over in the interest of getting an American in space sooner even if it meant using less sophisticated technology. The system was reproposed in 1961 as the possible landing system for Gemini. Without the time constraints that had turned Mercury into a crash program, introducing Rogallo into Gemini had the potential to begin NASA’s move away from splashdown landings.
Design and construction of the system was contracted to North American Aviation – the company behind the X-15. The theory of the paraglider was simple: an inflatable wing would turn the ballistic spacecraft into a glider prior to landing. The successful Paresev program proved the paraglider’s pilotability, but the full-scale inflatable wing refused to translate into a viable system. The theory refused to translate into practice, and all ten manned Gemini missions ended in splashdown. (Right, a schematic of the proposed landing sequence for Gemini using the Rogallo wing.)
NASA Associate Administrator George Meuller formally removed the paraglider from the Gemini program on February 20, 1964. It was downgraded to a test program; NAA would continue development of the system as stipulated in their contract with NASA, but the end result would never be a paraglider assisted landing.
As part of the final development, NAA was given the green light to prove Gemini’s pilotability when the spacecraft was mated with an already inflated Rogallo wing – failure to inflate was the main problem of the paraglider’s development, so testing with an inflated wing was the best alternative.
Proof of pilotability called for a full-scale drop test. The Gemini-Rogallo spacecraft was brought by helicopter to an altitude from which the NAA pilot inside would land the spacecraft as though coming from orbit. Like the Paresev tests, the first flights would be tow tests before the pilot attempted a free fall test.
Charles Hetzel, one of the seven pilots who flew the Paresev, manned the Gemini capsule for the first captive landing test in July 1964. The flight was a success. Hetzel flew for close to 20 minutes, still attached by a towline to the helicopter, before making a successful landing. (Left, the Paresev 1A in flight just prior to landing. 1962.)
On August 7, Hetzel attempted the first free flight of the Gemini-Rogallo configuration. The helicopter lifted Gemini to altitude without problem, but as soon as Hetzel severed the towline the spacecraft entered into a violent spin and he was forced to eject. Hetzel broke a rib during the failed test; the spacecraft sustained only minor damage. The system was subsequently revised and NAA put the Gemini-Rogallo through a series of radio-controlled half- and full-scale landings over the next five months.
The next manned test flight of the Gemini-Rogallo took place on December 19, 1964. Donald F. McCusker severed the towline at altitude and executed a successful five-minute glide before hitting the runway at close to 30 feet per second – landing at such a high speed constituted a barely-controlled crash. McCusker sustained injury from the shock of his hard landing, prompting NAA to beef up the Gemini landing gear and shock absorption of the pilot’s seat.
NAA test pilots, including McCusker, made twelve successful landing with the Gemini-Rogallo configuration between November and December of 1965. By this time, the Gemini program was well under way with five manned flights completed. There was no question of NASA incorporating a paraglider landing this late in the program; the system worked, but success came about two years too late. (Right, damage to a half-scale Gemini spacecraft after a failed landing with the paraglider.)
In all, NASA had sunk four years and substantial funds into the development of the Rogallo wing with the hopes of a land landing for Gemini; the program cost close to 165 million 1960s-dollars on its development – nearly 1.2 billion 2010-dollars. Letting such extensive and costly research go to waste was not an option.
And so NASA began finding other applications for the Rogallo wing. At this time in the mid-1960s, it was the most well developed pilot-controlled land landing system the organization had, and splashdowns continued to be a costly and complicated landing method. NAA’s manned drop tests belatedly proved the system was viable, and general consensus was that more time for development could yield a flight-worthy Rogallo landing system.
The question of land landings in spaceflight was reopened in the mid-1960s as a possibility for Apollo. One proposal that went at least as far as preliminary studies on paper was a rotor landing system that worked like an autogyro. Four angled blades would deploy form the top of the Apollo Command Module. As the capsule fell through the thickening atmosphere, the blades would rotate with increased speed until they generated enough lift to slow the Command Module’s rate of descent. It would then touch down softly like a helicopter with the pilot in full control of the final landing point. (Pictured, the rotor reentry spacecraft. Source: NASA archives.)
Another contender was once again the Rogallo wing. Langley engineer Mac C. Adams, in a report covering the possible applications of Rogallo to Apollo suggested NASA conduct an intensive in-house research program to finally produce a working system. He concedes, however, that Apollo is unlikely to land with the paraglider. The system’s development is too far from completion. The end-of-decade deadline for a lunar landing couldn’t wait for a land landing system anymore than Gemini could.
Instead, he recommends the paraglider be incorporated into Apollo follow-up programs, the Apollo Applications Program (AAP) and the Apollo Extension Series (AES). Proposed in 1965, AAP and AES planned to build on the expected success of Apollo, moving from lunar landings to Earth orbiting laboratories and an at least semi-permanent manned lunar outpost. (Right, an artist’s concept of an early lunar outpost.)
Because AAP and AES were follow-up programs to Apollo, NASA would finally be without time constraints. These new programs offered the organization the freedom of time it needed to develop a working Rogallo wing.
With this long-term program in mind, NASA reopened contracts surrounding the paraglider. In 1967, the organization contracted Northrop Ventura – the sub-contractor that had built the sails used the in North American’s Rogallo program – to continue the research and development of the paraglider. The goal of the contract was not far from the original goal of the first Rogallo program: to establish the suitability of the system for pilot-controlled landings in a shallow glide.
Two years after Northrop Ventura was awarded the contract, development on the paraglider had stalled. In a 1969 internal letter, Director of the Space Vehicle Division of NASA’s Office of Advanced Research and Technology Milton B. Ames, Jr. wrote that the AAP was no longer considering the paraglider as a landing system. Although he was personally in favour of the paraglider, NASA, he wrote, was moving in the direction of reusable shuttle-type vehicles for its next generation of spacecraft.
Compounding the problems of this second paraglider program were the funding cuts to NASA in the latter half of 1969. In the mid 1960s the organization received over 4 percent of the US’s annual GDP. But this was unsustainable amount of money to dedicate to the space program, particularly after the success of Apollo 11 marked the completion of Kennedy’s goal. Funding was further cut after the near-loss of the Apollo 13 crew in April 1970.
Unsurprisingly, funding cuts took the greatest toll on the experimental programs that had already experienced problems or consumed substantial resources with little payoff. By the time the Apollo 17 flew in 1972, NASA’s budget had shrunk to a fraction of its Kennedy-era finding. The remainder of the Apollo program, Apollo 18, 19, and 20, had been cancelled. What resources from the program remained were transferred to the Apollo Applications Program, but the follow-up program was quickly turning from a freestanding effort to a last hurrah extension of Apollo. (Pictured, Jack Lousma (seated) and Gerald Carr train in the Lunar Rover Vehicle. Both astronauts had served as on Apollo backup crews and, according to the crew rotation schedule, were likely candidates for the canceled Apollo 19 or 20 mission. 1970.)
The AAP was eventually cancelled altogether, and the Apollo leftovers were put to use in the short-lived Skylab program; NASA’s first attempt at an orbiting laboratory comprised three missions between 1972 and 1974. The final Apollo hardware was put to use in 1975 on NASA’s end of the Apollo-Soyuz Test Program – the first cooperative mission between the Soviet Union and the US.
Skylab (right, in orbit) and ASTP never answered more than an immediate need, and their greatest purpose may have been to keep America in space between Apollo and the space shuttle. The decision to pursue the space shuttle effectively put the final nail in the paraglider’s coffin as far as its career with NASA was concerned. There was no hope for the Rogallo wing’s continued development; by 1976, development on the shuttle was well underway and it was only three years away from its first unpowered landing tests.
While NASA was gradually moving away from the paraglider landing system, the US Air Force remained interested in the land landing possibility for its own manned spaceflight program.
The USAF had long been interested in the military potential of space. Dynasoar – the never realized follow-up program to the X-15 that is often referred to as the precursor to the space shuttle – was formally cancelled on December 10, 1963. That same day, the USAF announced its new space program. The Manned Orbiting Laboratory (MOL) or Gemini B program was based on extending NASA’s Gemini program with the goal of proving the necessity of a military presence in space under the guise of proving man’s ability to work in space.
MOL was a larger version of the Gemini spacecraft; the principle difference was the addition of a laboratory the pilots could access through a hatch in the heat shield. With the preliminary work done by NASA on landing Gemini with the Rogallo wing, the USAF intended to use the same system to land each MOL mission; adapting it for the slightly larger spacecraft wouldn’t require significant hardware installations or major redesigns. Pending approval of the Department of Defense, production of Gemini hardware could continue after NASA formally ended the program for the benefit of the USAF, and this included Rogallo hardware. (Pictured, an artist’s concept of the MOL in orbit. Early 1960s.)
In late 1964, the USAF MOL program was less than a year old and the paraglider was already falling out of favour with NASA as the landing system for Gemini. Still, the organization stood behind the Rogallo wing as a viable technology for landings and supported its use by the USAF. Both NASA Deputy Administrator Robert Seamans and Langley engineer Albert Hall offered their support of the system, calling the paraglider an acceptable interim measure until a true long term solutions to landing from space can be found. (Right, a test launch of the USAF MOL. November 3, 1966.)
Bur the Rogallo wing fell out of favour with the USAF as it did with NASA. In a 1966 letter, USAF General Bernard A. Schriever draws the obvious parallel between Gemini and MOL. The constant problems Gemini engineers had with the paragalider were indicative of the trials MOL engineers would face with the same system; indeed, each program ran into the similar developmental failures and schedule setbacks.
Schriever admitted defeat. A successful paraglider would require substantial redesigns and testing. While it might take the place of ocean-borne recovery methods, the cost of research and development to that point would exceed the sum NASA had already spent working on the paraglider. It just wasn’t a viable option. The Rogallo wing was never included in MOL, and the project itself never progressed to manned flight.
The paraglider was alive with NASA and the USAF for almost a decade. In theory it was the perfect solution to the landing problem – lightweight, pilotable, and wouldn’t require substantial changes to the already existing spacecraft. That a decade of research and development couldn’t yield a successful paraglider landing, however, suggests the problem lies with the design more than the NASA or the USAF’s approach. An inflatable wing meant to act at once like a parachute and a fully controllable glider is a tall order. NASA built new spacecraft capable achieving rendezvous in orbit and landing on the moon, but the Rogallo wing always remained just out of reach.
Suggested Reading/Selected Sources
1. Milton Thompson with Curtis Peebles. Flying without Wings. Smithsonian Institution Press. 1999.
2. David Shayler. Gemini: Steps to the Moon. Springer Verlag. 2001.
3. Virgil I. “Gus” Grissom. Gemini: A Personal Account of Man’s Venture into Space. The Macmillan Company. 1969.
4. Hacker and Grimwood. On the Shoulders of Titans: A History of Project Gemini. Washington: NASA. 197
5. B. A. Schriever, “Gemini Paraglider for MOL”. Washington: NASA. 1966.
6. “Apollo Alternative Earth Landing System”, Research and Technology Resume, Washington: NASA. 1965.