More Lakes

Jack McKay conducted a short lake survey in late March 1961 to investigate possible launch lakes for the maximum speed flights. During this trip he visited Tonopah, Nevada, on 22 March to discuss communication requirements, refueling capabilities, and storage requirements. The officer in charge of the Tonopah site stated that F-104 proficiency flights would not be a problem. A 500-gallon fuel truck was available with 91-octane gasoline to refuel H-21 helicopters. The pilot would sign a Form 15, committing the AFFTC to reimburse Tonopah for the fuel. Storage facilities at the airport were limited to a small U. S. Navy installation that consisted of one small, corrugated-metal building leased to the Atomic Energy Commission for the storage of classified materials. However, a fenced area around the building appeared suitable for securing X-15 support equipment if necessary. The manager of the civilian airport informed McKay that 91- octane fuel was available for purchase from a 2,000-gallon fuel truck.-104-

McKay also visited Smith Ranch Lake, located 100 miles north-northwest of Mud Lake. The Air force initially acquired this site as a backup to Wah Wah Lake and removed a total of 25,000 acres from the public domain, although some privately owned land also existed on the southwest portion of the lakebed. A five-mile-long runway was marked on a heading of 025-205 degrees. McKay also investigated the use of Edwards Creek Valley Dry Lake, 26 miles northwest of Smith Ranch during the March 1961 trip, but took no further action.-105-

The increased performance of the "advanced X-15" (the X-15A-2) and its use of recoverable drop tanks necessitated that NASA and the AFFTC acquire rights to additional property. All of this land was in Nevada. Most of it was owned by the federal government, and a great deal of it was already out of the public domain.-106-

The X-15A-2 would use drop tanks on the high-speed flights, something that researchers had not anticipated for the original X-15 flight program. The X-15 jettisoned the tanks at approximately Mach 2.1 and 65,000 feet. After some free-fall, the parachutes opened at 15,000 feet and lowered the empty tanks to the ground. With the chutes deployed, the heavier tank had a descent rate of 25 feet per second (17 mph), while the lighter tank fell at 20 fps (14 mph). A helicopter recovered the tanks and placed them on flatbed trucks for the trips back to Edwards. Obviously, the program could not allow the tanks to fall onto civilians or their property. The possible impact areas for the tanks were quite large due to possible dispersions in the X-15 flight conditions at the time of tank jettison, as well as unknown wind effects.-107-

Despite its increased performance potential, the initial of the acceleration of X-15A-2 with full external tanks was considerably less than that of the standard X-15. This caused a reevaluation of the emergency lake coverage for flights with external tanks. Flight planners Robert G. Hoey and Johnny G. Armstrong used the AFFTC X-15A-2 hybrid simulator to conduct a parametric study of the glide capability of the aircraft for different engine burn times along the design profile to 100,000 feet. This study concluded that, of the originally selected launch points, only Mud Lake was suitable for flights using the external tanks. However, since Mud Lake was only 215 miles from Edwards, it was not suitable for the high-speed flights that required more distance. The use of Smith Ranch as a launch point was desirable, but unfortunately the distance between Smith Ranch and Mud Lake was too great for the glide capability of the airplane, and thus for a period of time X-15A-2 would have been without a suitable landing site. NASA wanted to find a usable lake between Smith Ranch and Mud Lake to fill the gap.

NASA conducted a new survey in May 1965 and again focused on Edwards Creek Valley Dry Lake, something that Jack McKay had mentioned as early as March 1961. This lake was 23 miles northwest of Smith Ranch; in a change of rules, there would be no plan to land at Edwards Creek, even in the event the engine failed to ignite immediately after launch. The lake did not provide the desired emergency coverage, but allowed a straight-in approach to Smith Ranch if an engine shutdown occurred at the worse possible time. In addition, if an emergency occurred at the time of tank ejection, the pilot could always land at Smith Ranch.-108

Johnny Armstrong carried out a further analysis of X-15A-2 flight profiles in early 1965 using the hybrid simulator. For instance, Armstrong studied the glide capability of the X-15A-2 by terminating engine thrust at different times along the Mach 8 profile. For X-15A-2 flights with external tanks, there were two critical points along the flight profile with regard to emergency landing sites. The first point was the decision to either to continue straight ahead to a forward landing site or initiate a turn to a landing site behind the airplane. The geographical location of potential emergency landing sites determined the length of this period. Second, the flight planners had to consider emergency lake coverage from the tank drop point. In all cases, it was desirable to arrive at the emergency landing lake at an altitude of 20,000 feet or greater.109

In his preliminary study the previous summer, Armstrong had concluded that launches from Mud Lake needed to be conducted from the east side of the lake because of external tank impact considerations, and this condition still held true. If a pilot was considering contingency landing sites, the critical time for a launch from Mud Lake was after 53 seconds of engine thrust; at that point it was possible to either continue forward to Grapevine Lake or turn around and land at Mud Lake. If the pilot elected to continue forward, he would arrive at Grapevine at an altitude of 43,000 feet. Returning to Mud Lake would result in an altitude of 11,000 feet (or 6,000 feet above Mud Lake).118

The simulations also showed that adequate emergency lake coverage was not available for a Smith Ranch launch. There was a period of 29-31 seconds (depending upon the exact launch point) during which the X-15 could not go forward or turn around and arrive at the emergency landing site at 20,000 feet altitude. Worse, there was a period of 4-7 seconds in which it was not even possible to arrive at the emergency lakes at 5,000 feet altitude. In other words, given that Mud Lake was at 5,000 feet altitude, the pilot could not even make a straight-in approach if the engine shut down during the critical time. Additionally, if the engine shut down during external tank separation, the X-15A-2 could not go forward to Mud Lake and would have to return to Smith Ranch, arriving with only 5,000 feet altitude.111

The use of Edwards Creek Valley as a launch lake allowed the pilot to attempt a straight-in approach at either Smith Ranch or Mud Lake if the engine shut down at a critical time. There was even a small period in which the pilot could elect to abort to either lake. Once the pilot jettisoned the tanks, he could turn the airplane back to Smith Ranch, arriving at 5,000 feet. Given this analysis, the program decided that X-15A-2 high-speed flights would proceed from either Mud Lake or Edwards Creek Valley. The tank recovery area for Mud Lake launches was entirely within Restricted Area R-4907 and posed only minor problems for securing use rights; however, the Air Force needed to acquire use rights for civilian property in the anticipated drop areas for Edwards Creek Valley (and Smith Ranch) launches.-1112!

based on two considerations: first, the airplane had slightly better gliding performance than anticipated, eliminating most of the gaps in emergency lake coverage from Smith Ranch; second, there had been some difficulties obtaining adequate external tank drop areas from Edwards Creek Valley. As it turned out, there never were any launches from Edwards Creek Valley since the X – 15A-2 program stopped at Mach 6.7 instead of proceeding to Mach 8. Of the four flights with external tanks, the program launched the first (with empty tanks) from Cuddeback, and the three flights with full tanks from Mud.113

Rogers Dry Lake was the designated landing site for all flights. Initially, the runways on Rogers were marked in typical fashion, showing left and right extremes, and thresholds on each end. A meeting of the original X-15 pilots on 19 October 1960 established a standard operational procedure for releasing the ventral stabilizer before landing. North American decided the pilots should jettison the ventral below 800 feet altitude and less than 300 knots to ensure recovery in a reusable condition. The pilots established that if the touchdown point on runway 18 (the most frequently used) was two miles from the north end, then the ideal jettison queue would be when the pilot passed over the railroad tracks located one mile from the end of the runway. The pilots asked Paul Bikle to request the AFFTC to mark all Rogers runways with chevron patterns one mile from each end (to indicate the ventral jettison point), and also two miles down each runway (to indicate the touchdown point). The program subsequently adopted these markings for most of the lakebed runways.-114

The markings on the lakebed were not paint, but a tar-like compound on top of the soil. The Air Force standardized the runways at 300 feet wide and at least 2 miles (often 3 miles) long. The tar strips outlining the edges of the runways were 8 feet wide. The width of the strips was critical because they provided a major visual reference for the pilot to judge his height (many of the lakebeds were completely smooth and provided no other reference). The chevron patterns were marked at the appropriate places on each lakebed with the same compound. The Air Force was responsible for keeping each of the active lakebeds marked, and laid new tar at least once per year after the rainy season. If the pilots complained the markings were not visible enough during the approaches practiced in the F-104s, the Air Force would re-mark the runway. As Milt Thompson remembered, "over the years, the thickness of the tar strips increased with each new marking until they exceeded 3 or 4 inches in height____________________ "1^115!

The FRC was primarily responsible for checking the lakebeds during the course of the flight program. As often as not, this involved landing the NASA DC-3 on the lakebed for a visual inspection (usually performed by Walter Whiteside riding a motorcycle). If the lakebed appeared damp, the pilot of the DC-3 would make a low pass and roll its wheels on the surface, making sure not to slow down enough to become stuck. He would then fly a slow pass and observe how far the wheels had sunk in the mud. If the DC-3 was not available, the pilots used a T-33 or whatever other airplane they could get, although obviously they could not carry the motorcycle in those instances. On at least one occasion, the pilots (Neil Armstrong and Chuck Yeager) became stuck in the mud when the lakebed turned out to be softer than they had anticipated.-116

The National Park Service declared Rogers Dry Lake a national historic landmark because of its role in the development of the nation’s space program. Since 1977, NASA has used the lakebed as a landing site for many Space Shuttle test and operational flights.-117!

Despite the time and effort spent on locating, acquiring, and marking many launch and intermediate lakes, none of the X-15 pilots had any real desire to land on any of them, although several did. The pilots considered a landing at the launch lake or an intermediate lake an emergency, while landing on Rogers Dry Lake was normal. Both were deadstick landings, so what

was the difference? Milt Thompson summed it up well in his book: "[Rogers] was where God intended man to land rocket airplanes. It was big. 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." In other words, it was home.-1118!