At the Edge of Space

by Milton O. Thompson

  The Dyna-Soar pilots spent weeks at Johnsville on the centrifuge verifying that we could manually fly the booster under the g loads involved during acceleration into orbit. We traveled extensively to each of the subcontractors to participate in their design process. We were fitted with newly designed pressure suits, and were invited to observe a launch of a Titan booster similar to the one that would boost Dyna-Soar into orbit. We were the USAF’s version of the Mercury astronauts. The USAF would have really eclipsed the Mercury program if it had flown Dyna-Soar, but DOD made the decision to cancel the program in 1963.

  What a crime. What shortsightedness. I believe Neil Armstrong sensed that Dyna-Soar was going to be cancelled. He applied for a position as a NASA astronaut before Dyna-Soar was cancelled and was selected as a member of the second group in 1962. I was simultaneously named as the only NASA Dyna-Soar pilot out of a total of six Dyna-Soar pilots. Al Crews, another USAF pilot, replaced Bill Dana as a Dyna-Soar pilot. When Dyna-Soar was cancelled, Al Crews was assigned as the chief MOL pilot. He later transferred to NASA as an astronaut when MOL was cancelled, but he finally gave up waiting to fly into space and transferred out of the astronaut office into the flight operations division so he could at least fly airplanes. He is the only man I know who was named an astronaut on three different programs, Dyna-Soar, MOL, and Apollo. He waited over 15 years for a space flight and finally decided that it was not meant to be.

  As a result of my participation in Dyna-Soar, I had the distinction of being one of the world’s first unemployed astronauts. For some reason I was not able to draw unemployment compensation.

  During my participation in the Dyna-Soar program, I happened to attend a briefing by Francis Rogallo on his Rogallo Parawing. He proposed that for one of its many possible uses, it could be used as an alternative to a parachute for recovery of space capsules, such as the Gemini capsule. I was quite impressed with his proposal and talked to Paul Bikle, our director after Williams left, about building one and flying it in a low-key program using part-time personnel. Bikle was not interested since we were by this time heavily committed to the X-15. I then talked to Neil Armstrong about building one at home and he expressed an interest in working with me.

  We came up with a design and then began scrounging around for parts with which to build it. Bikle heard about our efforts and finally decided to approve an official effort to build a flight vehicle. I think he did this to prevent Neil and me from killing ourselves with our own marginal design. The vehicle was built in Dryden’s shops using simple light aircraft construction techniques. We tried constructing our own cloth membrane for the wing, but finally contracted a sailmaker to fabricate one. We began flying the vehicle while towing it behind one of our utility trucks. We towed it up and down the taxiway between our facility and the tower for several weeks while I learned to fly it. Finally, we towed it up to 5,000 feet altitude with a Piper Supercub and I made the first free flight of a Rogallo hang glider in March 1962.

  That first vehicle had a lot of problems. It was severely damaged during the checkout of another pilot shortly after its first flight. We encountered numerous problems developing a good flightworthy vehicle, including several spectacular crashes, but we finally constructed one that was successfully flown by a number of different pilots, including Neil Armstrong and Gus Grissom.

  Our early efforts with the Rogallo wing demonstrated that it could indeed be flown and controlled by a pilot. We were not, however, convinced that a practical system could be developed to recover the Gemini capsule. The Gemini system would utilize an inflatable wing, which was to be deployed and inflated after the Gemini capsule had slowed to subsonic speeds.

  Efforts by North American Aviation to develop a prototype system for Gemini spacecraft demonstrated the many problems associated with this concept for spacecraft recovery. The program was finally cancelled and Gemini was recovered in the water just as Mercury was—using a conventional parachute.

  My next interesting research program was the lifting body program. Lifting bodies were conceived as entry spacecraft that could fly during entry rather than plunge down into the atmosphere as the space capsules were designed to do. The lifting body concept was a spinoff of work being done in wind tunnels in the mid-1950s to develop stable, survivable missile nose cones.

  The early wind tunnel work indicated that blunt nose cones survived the heat of entry much better than sharp aerodynamically shaped nose cones. As a result, the early nuclear warheads were all blunt shaped cones with rounded noses. The engineers testing these shapes in the wind tunnel noted that these shapes could develop lift if they were ballasted in a certain way and they could develop even more lift if the blunt cone was slightly altered to enable it to achieve trim conditions at a positive angle of attack. Additional tailoring of the basic cone shape could produce a configuration that could actually fly almost like an airplane, if the necessary stabilizing and control surfaces were added. Several lifting body configurations were developed in the NASA wind tunnels and these shapes were proposed as candidate shapes for the Mercury spacecraft.

  The Mercury program selected a more conventional nose cone shape to minimize the testing required to finalize the design and expedite the development program. The lifting body concept languished in the archives in technical reports for several years until Dale Reed, one of our engineers, expressed an interest in building a manned flight vehicle. This renewed interest in lifting bodies surfaced shortly before the cancellation of Dyna-Soar. We were grasping at straws, trying to keep some momentum going in the concept of lifting entry. We believed that flying back from orbit was a much more dignified way than coming back in a capsule under a parachute and ending up in the ocean.

  I became interested in the lifting body concept and worked with the engineer who was proposing the flight vehicle to help him sell the idea. We finally convinced Bikle to build a low-cost manned vehicle to determine whether it would fly. We built the internal structure, the landing gear, and the control system in-house. We contracted the hull construction out to a local sailplane builder.

  The hull was constructed of plywood, using typical glider-sailplane construction techniques. The vehicle had no propulsion system, rather it was to be towed into the air and released for free flight in the same manner as were sailplanes. A suitable tow aircraft was readily available, our venerable C-47. We were not quite sure what to use for ground tow tests. I wanted to learn to fly the vehicle during ground tow, just a few feet off the ground, before we towed it to altitude with the C-47.

  We needed a vehicle that could tow the lifting body to speeds in excess of 80 MPH and, preferably, one that could tow it to over 120 MPH. Minimum takeoff speed was calculated to be 80 MPH. We eventually realized that we would need a very high performance automobile as a tow vehicle to achieve the desired speeds. Rough calculations indicated that the tow vehicle would need an extra 150 horsepower at 120 MPH to overcome the drag of the lifting body at that speed. We settled on a Pontiac Bonneville convertible as the desired tow vehicle. We bought the biggest engine that they offered.

  The U.S. government does not normally buy high performance convertibles, so we needed some manipulation of government procurement regulations. After purchase, the car was immediately delivered to a Los Angeles speed shop to be fitted with all the essential high-speed, heavy-duty racing components. Walter Whiteside drove the vehicle back to Edwards. Whiteside was the NASA employee who was to drive it during towing operations.

  The NASA driver was careful to stay well within the speed limits but about halfway home a California Highway Patrol vehicle began to tail him. The CHP vehicle tailed him all the way into the Antelope Valley and then turned on the red lights to pull him over. The CHP officer’s curiosity had finally convinced him to check out this high performance convertible with a roll bar and U.S. government license plates. I cannot say that the officer did not really believe the story that the NASA employee gave him in explanation, but the officer continued to follow him until he turned int
o Edwards Air Force Base.

  We tried to fly the M2-F1 lifting body while being towed by the Pontiac in the spring of 1963. I managed to get the M2-F1 airborne a few feet above the lakebed, but the roll control was too sensitive to maintain a stable roll attitude. We quickly decided to forgo any further flight attempts and instead, put the vehicle in a large wind tunnel at the Ames Research Center. We spent about a week testing the vehicle in the 40-by-80-foot tunnel at speeds up to 120 MPH. That was a very interesting series of tests. I sat in the vehicle during the tests to position the controls and expedite the testing. On completion of the testing, we made some control system modifications and then again began our ground towing operations to get the vehicle airborne. This time, the vehicle appeared to be flyable.

  For the next several months, we roared up and down the lakebed at speeds over 120 MPH, ten to twenty times a day. I evaluated the controllability, the handling qualities, and the visibility on and off the towline. We measured performance and added a small rocket motor to be used if we had a problem during the landing maneuver. Finally, I ran out of excuses and had to admit that we were ready to try a flight to altitude. Bikle had not informed headquarters that we were going to build the M2-F1. We built it in a curtained-off section of the hangar to minimize the visibility of the program. Bikle was concerned that headquarters might disapprove the project. By building it covertly, he avoided any confrontation until it was completed and ready to fly. He finally informed headquarters just prior to our first ground tow. He never did tell them about buying the Pontiac. It never became an issue. When he informed them that we were planning to make a flight to altitude, their response was, “Don’t kill anyone.”

  The test team gathered out on the south lakebed with the M2-F1 before daybreak on the morning of the scheduled flight. The C-47 was flown to the south lake in preparation for the towing operation. After checking out both the C-47 and the M2-F1, the tow-line was hooked up and we began the takeoff. Just as I rotated the M2-F1 to takeoff attitude, the towline separated from the C-47 and I quickly slowed to a stop. It was quite fortunate that the towline separated prior to liftoff, because our analysis indicated that we had a deadman zone during towed flight extending from the ground up to at least 500 feet. We could not dump the nose of the vehicle and gain enough airspeed to flare and land if a towline broke in that altitude band. The towline and hook on the C-47 were subsequently checked and found to be binding, which prevented the hook from fully locking in the closed position. Some quick modifications were made and we were ready to try again an hour later.

  This time, the takeoff was successful. We climbed up to 7,000 feet while circling the north lakebed and I released as we crossed the north end of runway one-eight on the north lakebed. The vehicle flew surprisingly well and the landing was a piece of cake. The flight was very impressive to the observers on the ground due to the extremely steep flight path (approximately 30 degrees). The flight was a complete success. We flew the vehicle a week later for the news media and then checked out several more pilots including Chuck Yeager.

  We continued to fly the vehicle for another year, gathering data on its flight characteristics. We achieved our primary objective much sooner. Shortly after the first flight we got NASA headquarters’ approval to build two high-performance lifting bodies to investigate the transonic and supersonic characteristics of these unusual flying machines. I flew a number of other more mundane research programs in various other aircraft, but these were the fun ones.

  Having this background, I joined the X-15 program. I should not have been too impressed with the X-15. After all, it could only fly 4,000 MPH. I had been routinely flying spacecraft simulators in and out of orbit at speeds up to 18,000 MPH. My attitude quickly changed on my first flight.

  The X-15 was impressive. It had awesome power compared to conventional aircraft. It could accelerate at close to 4 g just prior to burnout, or about 90 MPH faster every second. It had such tremendous power that it could quickly tear itself apart after launch if it were not pointed uphill immediately. It was, without question, the most impressive aircraft that I have ever flown.

  MY FIRST FLIGHT

  My first flight in the X-15 was to be a major step up in performance compared to any previous aircraft that I had flown. However, it was a step down from the X-20 that I had been scheduled to fly. I did not get a chance to fly the X-20 but now at least I would fly the X-15.

  On my first X-15 flight, I was scheduled to fly a rocket airplane to Mach 4.0 and then maneuver it in a glide to an honest-to-God unpowered landing. Prior to my first X-15 flight, I had never flown a rocket airplane. I had never flown faster than Mach 2 and I had never really made a deadstick landing in a high performance jet aircraft. I had made a deadstick landing in a T-33 after shutting the engine down due to a persistent overheat light, but I was over the lakebed when I shut the engine down, so it was a piece of cake. I had also made a couple of deadstick landings in crop dusting airplanes and some glide flights in our paraglider research vehicle and the lightweight M2-F1 lifting body, but all that deadstick landing experience was child’s play compared to the upcoming X-15 landing. I was graduating to the big league.

  An X-15 landing was the ultimate in deadstick landings. The X-15 came down steeper and faster than any other existing aircraft and it landed a lot faster. According to the experts at Edwards, if you could deadstick the X-15, you could deadstick anything.

  When I saw the flight plan for my first flight, I quickly realized it was going to be a real challenge. I was going to be dropped from a B-52 bomber 130 miles away from Edwards and I was going to have to learn to fly that airplane well enough in 6 minutes to be able to make a successful deadstick landing. Once I was dropped from that B-52, there was no turning back. I was on my own. I was going to be on the ground one way or another in less than 10 minutes. I would either make a successful landing, come down in a parachute, or wind up in a smoking hole. I could be forced to land at the launch lake due to no engine light, or I could be forced to make an emergency landing at an intermediate lake. The best I could hope for was a successful unpowered landing back at Edwards.

  Where I landed depended mainly on the engine, although failures in other systems could dictate a premature landing short of Edwards. If the engine failed to light or did not develop full thrust, I would land at the launch lake. If the engine lit and developed full thrust but shutdown before I had enough energy to get to Edwards, I would probably end up at one of the intermediate lakes.

  I had to consider and plan for each of these possibilities. I personally prayed that the flight would go smoothly according to plan. I did not need an emergency on my first flight. I had more than enough to worry about. It’s surprising how the mind works. A landing at the launch lake or an intermediate lake was considered to be an emergency, while a landing at Edwards was considered normal. Yet the landing was a deadstick landing in any case, so why was one considered an emergency and one considered normal?

  To me, there was a tremendous difference psychologically. The big difference was that Edwards was home. It was where God intended man to land rocket airplanes. It was big (13 miles long by 4 miles wide). It had many different runways. It was hard. It had no obstructions on any of the many approach paths. It had all of the essential emergency equipment. It was territory that we were intimately familiar with and it had a lot of friendly people waiting there.

  It was an ideal place to land unpowered airplanes. God, in his infinite wisdom, knew that someday man would fly rocket airplanes, so he fashioned an ideal site to land them, the Edwards dry lakebed. We had many other dry lakebeds available for use, but none were as good as Edwards. All were smaller. Some were softer, some were only wide enough for one runway, some had mountains obstructing the approaches, all had limited temporary emergency equipment, and none had any friendly people. All of the launch or intermediate lakebeds were miles from civilization and were only accessible by dirt roads. The only living creatures at these other lakebeds were lizards, sidewinder
s, coyotes, tortoises, and jackrabbits.

  The launch lakes were usually good lakebeds with 3 to 4-mile runways, whereas, the intermediate lakes were usually smaller with runways as short as 2 miles. Some of the intermediate lakes were on plateaus and others were down in valleys with steep mountains surrounding them. A couple of them were so soft, we were reluctant to land the Gooney Bird on them. Before I launched on a flight, I always said a little prayer. “Please God, don’t let the engine quit halfway. Let it quit early or let it quit late, but never at such a time that I’ll have to go into an intermediate lake.” That prayer worked every time except once.

  In the early rocket airplanes, each new pilot was given a glide flight before a powered flight. This allowed the aircraft to be launched at an optimum location for an unpowered approach and landing. It also allowed the pilot to concentrate on one task, the unpowered landing. He did not have to worry about getting home to Edwards or about any rocket engine problems. The original X-15 pilots, after Scott Crossfield, did not get to make glide flights, but they did make low-speed flights around Edwards on their first flights using the interim XLR-11 engines. This again minimized the possible emergency situations.

  To me, either of these approaches made a lot of sense. I would have preferred to separate the challenges into several flights, rather than combine them all in one. But, someone smarter than I decided that a powered flight to a moderate speed was a more benign flight than a glide flight or a low-speed flight around Edwards. What that smarter person did not realize was that the program had gained a lot of experience in over ninety flights before Joe Engle and I made our first flights. Program personnel considered a Mach 4.5 flight to be very benign and to them, it actually was. To me, it was more than twice as fast as I had ever flown before and the entire operation was a whole new world. These X-15 people were routinely flying out to hypersonic speeds and into space. They had their own language and their own drummer that they were marching to and I was going to be a part of that new world if I could make a successful first flight. I was really impressed, but I was also worried. Would I qualify?