Finishing Up at Foster: Operation Mobile Zebra

Arnold had many adventures at Foster flying the F-100, but you’re just going to have to wait for the book for those. I don’t want to give up all my secrets! I’ll talk about one of them that occurred before he moved on to Texas A&M to finish his engineering degree.

By 1957, Arnold had paid back his three-year commitment to the Air Force for pilot training (ah, the good old days — I think the commitment is up to ten years now). Although he could return to his job at General Mills, he and Colleen were enjoying the year-round warm weather in Texas and were in no hurry to head back north. The balloon job gave him freedom to be creative and he enjoyed flying the balloons, but he really couldn’t see himself being a balloon pilot for the rest of his life. In addition, he wanted to design and fly airplanes, not balloons. Flying for the airlines was a long shot – the airlines were still feasting on the glut of pilots produced by World War II and Korea.

If he wanted to fly and make decent money doing it, the Air Force seemed like the best option. Given that, what to do next? The obvious unfinished business hanging over his head was his incomplete engineering degree. If he could finish that degree, maybe he could become an experimental test pilot, or design airplanes in the Air Force. After talking with his superiors, he decided to apply for an Air Force program that would send him back to school.

While Arnold awaited the results of his application, he took part in his last Foster adventure during an operation dubbed Mobile Zebra in the fall of 1957. Zebra was the Air Force’s first attempt at rapidly deploying a gaggle of 47 aircraft across the expansive Pacific Ocean. KB-50 tankers were to refuel the aircraft along the way. Arnold’s role in the exercise was only as a spare, which must have been a relief to Colleen, now stuck at home most of the day with two children under two-years of age (one of them was me).


A Souvenir from Mobile Zebra Showing the Route
(Arnold Ebneter Personal Collection)

The first part of the exercise called for Arnold to fly to George AFB with 19 other F-100s – 16 of them primary aircraft and four spares. After spending the night at George, the pilots planned to take off and refuel 500 miles later over the Pacific, with only the 16 primary airplanes continuing to Hawaii. If one of the primary airplanes or pilots had a problem, one of the spares would replace him. Arnold was the fourth spare, so four of the primary aircraft would have to drop out before he had to continue to Hawaii. Given that, Arnold expected to turn around and head back to George for another overnight stay and then head back to Foster. He told Colleen he should be home for dinner two days after he left. However, the ambitious deployment had pushed the limits of the exercise planners, and it showed not long after the exercise began.

The flight to George was routine, and by noon the next day, the pilots had taken off again. After flying for about an hour, the 20 airplanes spotted the KB-50 tankers. As they headed towards the tankers, pandemonium broke out. The lead pilot’s radio wasn’t working and the gaggle hadn’t rehearsed what to do if that happened. Everyone started trying to talk on the radio and when more than one person talks on the radio at once, all it does is squeal, and no one can talk. This is called “stepping on each other,” and step on each other, they did. In the ensuing chaos, four of the primaries didn’t refuel, and they turned back with barely enough fuel to land at George. Arnold and the other three spares, who had all refueled, continued toward their unexpected Hawaiian vacation.

The next day, Colleen’s concern over Arnold’s dinner no-show turned to alarm as the night dragged on. When she called the operations desk at his squadron the next morning, the duty officer answering the phone said, “Why, ma’am, your husband had to deploy.” That no one had bothered to call Colleen to let her know didn’t seem to strike him as a problem – wives and children were not an Air Force priority during the Cold War. In the meantime, Arnold was sitting in a briefing room in Hawaii, preparing for the next leg of the trip to Guam.

Colleen settled in to wait for a postcard or letter from Hawaii, or perhaps Guam or Japan, but nothing came during the two-month deployment. Arnold claimed there was no time to write a letter and a letter would take too long to reach Victoria anyway. He must have realized he was in trouble though, as he bought her a string of pearls in Japan.

Foster AFB Gets the F-100 and Some Wild Rides

In mid-1955, Arnold’s unit at Foster switched to flying the newer F-100, which was much sleeker and faster than the chubby-looking F-86. Arnold had already fallen in love with the F-100 in January, when he saw one during a visit to Eglin AFB in Florida. Much bigger than the F-86, he thought it “sort of mean and ugly-looking.” Although he couldn’t wait to fly one, the F-100 was grounded at the time to fix severe problems with the control system.

Despite the problems, however, North American had already started delivering F-100s to George AFB in California and by July 1955, the planes began appearing at Foster. Since Arnold was an assistant maintenance officer, he was one of the earliest pilots to check out in the F-100. He came close to crashing on his first flight in August 1955. Using the procedure the instructor had taught him, as soon as he took off the airplane began a pilot induced oscillation – a wild series of climbs and dives like a porpoise.


Arnold’s squadron, the 452 Fighter Day Squadron, flies by at Foster AFB
From Arnold Ebneter personal collection

Although the term “pilot induced oscillation” makes it sound like it’s the pilot’s fault, it’s not. Instead, the control system in the airplane has a problem so that whenever the pilot tries to fly the airplane, it begins to oscillate. The only way to stop it is for the pilot to let go of the stick or freeze it in one position. Some oscillations are benign – even the Wright Flyer had a mild one – but some can tear an airplane apart and kill the pilot. An oscillation on takeoff or landing is especially dangerous because of the increased chance of slamming back into the ground.

Fortunately, after several cycles of almost crashing into the ground, Arnold realized what was happening. He relaxed the pressure he held on the stick at the top of the next cycle and the airplane smoothed out. Several other pilots had similar experiences on their first takeoffs, some of them even banging onto the runway again after lifting off. The F-100 pilots quickly reverted to using the same takeoff procedure they had used in the F-86 and the wild rides ceased.

Another distinct F-100 feature was due to the afterburning engine the airplane used to break the sound barrier in level flight. Unlike later afterburners that lit in stages, the F-100’s afterburning engine was an all-or-nothing affair that delivered a jolt to the pilots as it lit. An F-100 taking off had a distinctive sound not heard before. The engine first screeched like a banshee as it spooled up to full military power. As the pilot moved the throttle to maximum power to light the afterburner, the screeching stopped for a fraction of a second. The afterburner then kicked in with a thud followed by roar as it propelled the airplane down the runway and into the air. A flight of four F-100s taking off left anyone near the runway unable to hear for several minutes until the noise faded into a low rumble as the airplanes disappeared on the horizon.

I remember hearing this noise many times as a kid, and even though I haven’t heard an F-100 in probably 30 years, I think I would still recognize it!

Foster Air Force Base and Jets: The T-33 and F-86

Congratulations to Bryan Stinekens for correctly answering the question about the balloon registration number N7927A! It is the same registration number used on the E-1, Arnold’s world record setting airplane. And now, back to pilot training.

After finishing primary flight training at Goodfellow in early September 1953, Arnold was assigned to Foster AFB for advanced training. Foster AFB was located near a small town named Victoria, close to the Gulf Coast. Even in September, the heat and humidity were oppressive.

The cadets were assigned to small “flights” of three students, each led by an instructor. A flight with two Belgian students and a Norwegian student was appropriately named the “Falstaff Flight,” but Arnold’s “riff raff Flight” seems to have been assigned as a whim by the pilot training leadership. Other cadets endured colorful names such as “Yo Yo,” “Odd Ball,” and “Moonshine.”

At Foster, the cadets first flew the 800-horsepower T-28A. Once they were used to flying the more powerful airplane, they switched to a jet trainer, the T-33A. Arnold’s first flight in the T-33 was on the Monday before Thanksgiving, on November 23rd.


Arnold flying T-33s at pilot training, Foster AFB 1953
From Arnold Ebneter personal collection

The Air Force commissioned Arnold as a second lieutenant and awarded him his silver pilot’s wings on March 15, 1954. After graduating, Arnold took two weeks of leave before reporting for his next assignment at Nellis Air Force Base, just north of Las Vegas for additional training. With no time to spare, he made a mad dash to St Paul and married Colleen on March 18, ending her patient two-year wait as he romped around the United States flying airplanes.

After the wedding, the furious pace continued unabated; Arnold and Colleen drove west to Las Vegas, arriving in time for a short honeymoon before beginning the next phase of his training.

At Nellis, Arnold learned to fly the F-86, which was then the Air Force’s frontline fighter. After F-86 training, he returned to Foster, along with five of the other top cadets in his class for his first real assignment, this time with Colleen in tow. Although Foster had been a training base when Arnold left, by the time he returned it was an operational fighter base assigned to the Tactical Air Command, which was responsible for most of the fighter aircraft in the Air Force.

The F-86 could fly faster than the speed of sound in a dive, and the pilots started “booming” Foster AFB every afternoon at 4:30 to announce the beginning of the retreat ceremony that signaled the end of the official day. One pilot would climb to a high altitude directly over the base, and then point the nose of his airplane at the ground. As the airplane accelerated through Mach 1, a loud cracking noise shook the ground below, rattling windows and waking babies. Although the nearby Victoria residents loved the daily air show, senior Air Force officials weren’t amused and soon told the pilots to knock it off.

Arnold Ebneter: Balloon Pilot

Arnold became a balloon pilot on January 23, 1951. The balloon program had temporarily moved to the US Army’s White Sands Proving Ground. Now called White Sands Missile Range, the range is located in the south-central part of New Mexico, about 50 miles northwest of El Paso.

AE_Jan 1951

Arnold’s First Balloon Flight, White Sands Proving Ground, New Mexico

For Arnold’s first flight, the weather was typical for a January morning in New Mexico, sunny and chilly, but much warmer than the twenty below zero temperatures he and Charlie had left behind in Minneapolis. Since Arnold’s first flight was to try out some of his design changes, he had become a test pilot as well. He also carried an anchor he and Charlie hoped might provide for easier landings than the garden hose/rope combination they were using, especially during the windy conditions they were more likely to encounter in New Mexico. Both pilots had noticed that colorful drawings of balloons from the 1800s often depicted balloons with anchors, so they assumed the anchor must be a good way to stop a balloon. The anchor Arnold designed looked like a very large treble fishhook, weighed about two pounds, and attached to the balloon with a 100-foot nylon line.

Arnold and the balloon lifted off easily and after rising quickly to 1000 feet above the ground, he began drifting on a southwest heading toward the town of Las Cruces. After clearing the Organ Mountains, a small range of hills dividing White Sands from Las Cruces, he dropped down to about 200 feet above the ground, and flew silently for an hour, enjoying the desert sights below.

When it was time to land, Arnold decided to try out the anchor first. After descending a bit, he dropped the anchor from about 100 feet and snagged it on a piece of sagebrush. If there had been no wind, everything would have been fine; the anchor would have provided a stable platform. However, the 15-mile per hour wind blew the balloon sideways and turned Arnold into a human pogo stick — he banged onto the ground and then bounced violently back into the air. Although it might have made for a fun carnival ride, after three bounces Arnold had seen enough. He cut the anchor line, let the balloon climb back up, and then made an uneventful landing using the drag rope.

The ground crew chasing him in a Jeep arrived about ten minutes later to retrieve him and the balloon. However, they decided not to bother looking for the anchor, since Arnold had determined that, fanciful artist renditions aside, they were unlikely to try using it again. Somewhere in the wilds of New Mexico, that giant “fishhook” may still be waiting for someone to find it and wonder what sort of alien vehicle might have used it.

Arnold Ebneter: Accidental Balloon Engineer

About the time Arnold met Colleen, he also found a new job. His friend Charlie Moore was an engineer for General Mills, and he had a contract with the Navy to develop manned balloons that could stay aloft for up to twelve hours. Charlie had flown one manned flight in 1949, but he needed additional help to continue the program. He really needed three employees – another pilot, a mechanic, and an engineer – but he decided to hire Arnold because he could fill all three roles and thus save the program some money. Despite his lack of degree and his youth, by October Arnold was a General Mills employee and the project engineer for the balloon program. When the Minnesota National Guard activated on December 1, 1950 the Navy, not wanting to lose their prized new project engineer, arranged his to transfer to the Minnesota Air National Guard.

Despite the Navy perception of Arnold’s importance to their program, neither he nor Charlie knew much about manned balloons, and Arnold did not know much about balloons at all. However, if the balloonists-to-be had any doubts, the confidence of youth overcame them.


Charlie Moore in one of the General Mills balloons

Photos of these balloons do not inspire confidence that they could safely carry someone even five feet off the ground, let alone 5,000. Except for the use of a single balloon, the setup resembled a “lawn chair balloon” that Californian Larry Walters infamously used in 1982 to ascend to 15,000 feet, astonishing several nearby airline pilots. Federal authorities were not amused.

The GM balloons were legal, although the Navy took great pains to keep the program quiet. Each balloon was made of very thin polyethylene plastic and was twenty feet in diameter, when fully inflated with helium. Instead of the typical basket used on balloons to carry the pilot and passengers, the pilot dangled precariously below the balloon, attached using only the parachute for the instrument and a harness. With this unwieldy get-up, there was obviously no room for passengers, even if any had been willing to go for a ride.

Although Arnold modified later balloons with a plywood swing for the pilot to sit on, there was still nothing between the pilot and the ground, which made for interesting landings. The balloons leaked helium naturally, which caused the balloon to enter a gradual descent once it reached its maximum altitude on any given day. Once the balloon was about one hundred feet above the ground, the pilot would drop a one-inch weighted rope attached to the balloon. When the rope touched the ground, the weight of the balloon was reduced by the rope weight now on the ground, which caused the balloon to temporarily stop descending.

The pilot then brought himself to within five feet of the ground by simply hauling the rope into the basket; at five feet, the pilot pulled a balloon panel designed to rip away and deflate balloon, and the pilot dropped comfortably to the ground. Despite the simplicity of the system, it required a great deal of coordination and effort from the pilot. The landings could also become quite dicey when it was windy, as the rope did nothing to keep the balloon from blowing across the ground.