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Excerpt From Book I |
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Excerpt From Book I |
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A PROUD MAN’S TALE The
development of the and The evolution of a fighter pilot
to test pilot
Now
the proud man, since he deserves most, Aristotle (384 to
322 B. C.)
Yes, Aristotle, test pilots are proud men; we are good in the highest degree. And, Sir, you are right; I have never met a test pilot unbecoming of his profession. However, sometimes, unknowingly, we fly into danger. With the F-100 Super Sabre, we learned the hard way, and some paid for it with their lives. A SEARCH FOR PERFORMANCE The North American Aviation (NAA) F-100 Super Sabre was the first fighter in the USAF active service inventory capable of attaining supersonic speed in level flight. Although it was originally designed strictly for the air superiority role, it came into its own as a fighter-bomber and flew many of the early combat missions during the Vietnam War. The quest for a supersonic version of the Sabre began in February 1949. North American began work on a company-financed design study for an advanced version of the F-86 that would be capable of achieving supersonic performance in level flight. This study came up with a proposal to obtain this performance improvement by increasing the wing sweep from the 35 degrees of the standard F-86 to 45 degrees. Wind-tunnel studies indicated, however, that because of the steep rise in aerodynamic drag that takes place as near-sonic speeds are attained, only a relatively small increase in maximum speed would be attained by this change. Clearly, aerodynamic changes alone would not be sufficient to achieve supersonic speeds in level flight. More power would be needed-a lot more power. The next proposal, the Sabre 45 (the "45" indicating the angle of wing sweep) was to be powered by the new Pratt and Whitney J-57 turbojet, which was rated at 9,500 pounds "military" thrust and 15,000 pounds of thrust with an afterburner. Maximum speed was estimated at MACH 1.3 (871mph) at 35,000 feet, and combat radius was 680 miles. Estimated combat gross weight was 23,750 pounds; armament was to be a quartet of 20mm cannons. The Sabre “45” eventually attracted the interest of the USAF. By the way, the speed of sound is 760 mph at sea level. It decreases with increase in altitude. If a pilot indicates he is flying MACH 1 at sea level he is flying at 760 miles an hour. If a pilot is flying at MACH 1 at 35,000 feet he is flying at 670 miles per hour. Why is that you ask? Because the air is less dense! Less molecules of air! Therefore the sound wave moves slower. NAA asked that the USAF purchase two prototypes, one to be used for aerodynamic testing and the other to be used for armament trials. In October 1951, in spite of the misgivings of key development personnel who claimed that the design would be too costly and complex for a basic day fighter, the USAF council decided to press for the development of the Sabre “45” proposal. With the Korean War as a reminder of the perilous state of USSR/U.S. relations, the Air Force Council wanted the Sabre “45” in service in a hurry. The council thought that two prototypes would not be enough to achieve early operational status, and it recommended that the plane be purchased in quantity and full production initiated even before initial flight tests had been completed. This was a high-risk philosophy, but it would quickly give the Air Force a new plane if every systematic arrangement and design functioned as planned. On the other hand, if unexpected problems turned up during flight-testing, it would also risk the high costs and long delays of many in-service modifications. How real the risk of high costs, unexpected problems and long delays due to modifications turned out to be. However, considering the pressures of the war in Korea and the Cold War with the Soviet Union, the risk was considered worth taking. On November 1, 1951 (the day of my first supervised solo in pilot training---T-6, Lakeland, Florida), the Air Force issued a contract for two Sabre “45” prototypes plus 1110 production aircraft. On December 7, 1951 (10 years after the "Day of Infamy"), the USAF officially designated the Sabre “45” as the "F-100," the first of the Century Series of fighters--the series, in addition to the F-100, being the F-101, F-102, F-104, F-105, F-106, etc. The USAF designated the two prototypes as "YF-100." Following the mockup's inspection, North American reshaped the fuselage, and the horizontal tail was moved to below the chord plane of the wing; it was hoped that this would keep the tail clear of the wing wake at high angles of attack. It would also help to prevent the dangerous tendency of a swept-wing aircraft to pitch up suddenly and violently following a stall. This potential deadly phenomenon had come to be known as the "Sabre dance" and had caused numerous accidents in the F-86. But with the F-100, this thought never occurred to the engineers: what would happen if, at a high angle of attack near stall speed, the pilot went into afterburner---suddenly increasing the thrust by ½---from 10,000 10 15,000 pounds of thrust? I can answer that! For years, there have been sequential pictures on television-focusing on one of the most infamous of "Sabre dances." A young pilot was to ferry an F-100 from the North American plant in Palmdale, California, to his home base. After takeoff, his nose wheel would not retract, as it had cocked to an angle of 90 degrees. The pilot, with the gear down, was told to fly to Edwards AFB where the runway would be "foamed" to allow the nose wheel to slide along it. As he made his approach, he was going to be too short. Runway control kept telling him, "Pull up a little. Add more power-you're gonna’ be short--add power-pull, up-pull up." He was constantly being what to do by this excited runway controller. Naturally, he followed the instructions and pulled his nose increasingly higher. It was tough to see over the nose in an F-100 particularly at high angles of attack. To avoid a stall, the young, inexperienced pilot kept adding power until he rammed the throttle into afterburner. The J-57 engine responded with a controlled explosion-from 10,000 to 15,000 pounds of thrust at the snap of a finger. The F-100 was already in an angle of attack that was far too high. The excessive thrust pitched the plane to an angle of 90 degrees to the runway as the forward momentum "waltzed" the momentary pyre down the runway for a few short seconds until it rolled with a wing hitting the runway then pitching down and exploding into a thunderous ball of fire. The pilot did not survive. The fire trucks were on top of the accident in seconds. The pilot did not die of burn injuries. He died of asphyxiation-by his own vomit in his oxygen mask. The YF-100 that eventually emerged from the design changes outlined above was sufficiently different from that originally planned and was re-designated the "YF-100A" To reduce the tendency of the wing to twist during aileron deflection at high speeds, the ailerons were mounted inboard on the wing rather than near the tips. The YF-100A was somewhat unusual for its time in that it did not have wing flaps. The wing leading edge did, however, have automatic slats that were actuated by aerodynamic forces. These slats were intended to increase lift at takeoff, to delay wing buffet, to improve lateral control near the stall and to permit tighter turns. The slats on the F-86 series were functionally and aerodynamically the same. As the first YF-100A was nearing completion, the Air Force recognized that two prototypes would not be sufficient for the test program, and it decided that the first 10 F-100A’s off the line would be used as test aircraft as well.
BREAKS MACH 1 ON FIRST FLIGHT but ... The first YF-100A (52-5754) was completed on April 24, 1953. It was moved in high secrecy from the Los Angeles factory out to Edwards AFB. Chief test pilot George "Wheaties" Welch made the maiden flight on May 25, 1953 (the day of my 13th mission—flying an F-86--in Korea). The YF100A exceeded the speed of sound on its first flight, and the second YF-100A (52-5755) flew in October 1953. (The war had ended. I was test flying F-86’s in southern Japan.) On July 6, the YF-1OOA achieved a speed of Mach 1.44 (964.8mph) in a long dive from 51,000 feet. Every one at the plant was extremely excited, and rightly so! But early success in the nature of the F-100 came with a price. On the early test flights, there were problems with rudder flutter. The installation of hydraulic rudder dampers solved this; but that was only a mild harbinger of the more deadly things to come. USAF test pilots found that the YF-100A outperformed all other Air Force production fighters, but it had some serious shortcomings that might cause problems on introduction into service. Visibility over the nose was poor during takeoff and landing; longitudinal stability in high-speed level flight was considered inadequate; it also had what was known in test pilot terms as PIO or "minimum stick force per G" (to be discussed in more detail later). In other pilot parlance, the instability could lead to what was known as a "JC maneuver; Geee-suzz Kerr-riste." To make matters worse, its low-speed handling characteristics were rather poor, and it showed a tendency to yaw and pitch near the stall with the left wing dropping uncontrollably. Without afterburner, the climb rate was too slow; it took 16 minutes to get to 40,000 feet. Also, the landing was difficult and the touchdown speed was high. The short tail would become a telling tale. The F-100A was similar in most respects to the YF-100A, but it had a shorter, more stubby vertical tail with an increased chord. The chord is defined as a straight line that joins the leading and trailing edges of an airfoil-an airfoil being designed to provide a desired reaction force when in motion relative to the surrounding air. The change was a fatal mistake! The F-100A's mission was seen as being that of daylight air superiority, and it was seen as the natural replacement of the Sabre series of Korean War fame. The F-100A's armament consisted of four, 20mm cannons in the lower fuselage below the cockpit, each carrying 200 rounds. On New Year's Eve, 1953, (I was in Big Spring, Texas, where I won my wings 15 months earlier) the USAF directed that the wingtips on the last 70 F-100As’ were to be extended by 12 inches on both sides to improve roll characteristics and decrease the stall speed. About ten days after New Year's Eve, I would be reporting to North American as an Air Force acceptance test pilot; it was January, 1954.
ENTER THE LUCKY PILOT TEST FLYING THE F-86F,D,K,TF,T-28B AND THE XF, YF, F-1OOA & F-100C
On August 9,1954, Maj. Bill Woo]folk, the second in command of the Air Force office (he had flown the first F-l00A a few days earlier), handed me the "Dash 1"-the F-l00A pilot's handbook. He said, "Tomorrow's the day." That's all he said! I mean ... could I ask a few questions? "Questions about what?" he asked. "I've seen you on the F-100 flight-line; looks to me as if you have been living in the cockpit You probably know as much as I do. This is the first of 203 F-100As to be produced. You're the acceptance test pilot. Study the Dash 1. I'll see you in the morning. I'll answer any of your questions at that time." "Yes, sir," I said. I had our driver take me to the F-100 flight line. I put on my parachute and helmet and climbed up the ladder of the F-100, got into the cockpit, and sat down. I just sat there reviewing the cockpit, the instruments, the radios, the lever for the ram air turbine in the event of, God help me, an emergency. I checked the throttle for ease of reaching, the stick, the gear handle. And no flaps—this first flight will be different! It means extra approach speed. How will I handle that? I was mentally reviewing all of this because reports from the engineering test pilots were said to be agreeing with Air Force complaints that said the forward vision wasn’t that good during takeoff and landing. I had brought my parachute and helmet with me so I could match my sitting position with the adjustable height of the ejection seat. I wanted my helmet as close as possible to the top of the canopy. I wanted make sure I could see everything. I spent the next hour going over again, in my mind, every normal and emergency operating procedure. I drove to Panchos. I didn’t dare have a drink. I remember meeting Bill Richardson. He was with the love of his life. In thirteen months he would marry. Speaking of months, tomorrow, my first test flight in the world’s fastest fighter would make me, at that time, the only officer below the rank of Major to fly the F-100. I ordered Chinese. I asked Bill, “Where do the damn Chinese go when they want to eat out?” He laughed and said, “Probably to a restaurant by the name of Sing Sing Lu that specializes in Mexican food.” Gwen had to fly in the morning so she and Bill left after dinner. I went to my small but comfortable library in my second floor apartment, threw open the windows to the sea, and buried my face into the F-100 pilot’s handbook. I got to the flight line early. I tossed and turned all night; didn’t eat any breakfast. Was this my first combat mission all over again? My stomach didn’t know the difference. Major Woolfolk was there to help strap me in. He reviewed all the procedures with me—walk around—start—pre-taxi checks of instruments—controls—taxi, takeoff, climb out, the use of the afterburner, stalls—gear up, gear down—the practice of a simulated landing—the importance of critical airspeed on base and final—the use of the drag chute. The ground crew started the power unit that fed compressed air into the engine. I hit the master switch and as the RPM reached 20% I hit the ignition and brought the throttle ‘round the horn’ into idle. I immediately checked the exhaust gas temperature, the oil pressure, and the hydraulic pressure. The rpm was at 55%. The engine was making a hell of a racket; a high-pitched whine accompanied by a deep, prolonged guttural sound. It was a roar of excitement! Ten thousand horses ready to kick ass. God! this airplane is massive! I checked the flight controls and moved the stick to the right. The crew chief signaled right aileron ‘up’, left one ‘down’. God they were big. We did the same with left aileron input. I moved the elevator up and down to check pitch control. I checked the rudder. Everything was OK. I signaled ‘speed brake up’. I sensed 3000 pounds of hydraulic pressure ramming the pistons in the hydraulic actuator to the closed position. The crew chief was on one knee making sure it was flush and signaled so. He then disappeared under the airplane and shortly came into view holding three landing-gear pins. I showed him the ejection seat safety pins and the put them in my now soaking wet flight suit under my ‘Mae West’. I checked the instruments once more, made sure my pitch trim was set for takeoff, gave a big sigh, and put on my helmet and oxygen mask. I breathed in oxygen and checked the ‘blinker’. OK! I checked in with North American flight control, tuned to LA tower frequency, checked my flow of oxygen again and signaled to ‘pull the chocks’. Major Woolfolk had been watching my every move from the ladder attached to the side of the cockpit. I was ready to move forward with about 25,000 pounds of metal with wheels attached. When I gave the signal I was ready to taxi, he patted me on the head and stepped down. The ladder was removed. I was on my own. “LA tower, this is North American 5756— taxi, takeoff. “Roger, North American ‘56. Taxi runway 25 left, altimeter 30.01, wind from 28 (280 degrees) at 10 (knots.)” “Roger, LA. I am at the NAA revetment behind the wall.” “Have you in sight, ‘56. Clear to runway 25 Left.” I gave the ‘hundred’ a little power, moved forward, checked the brakes, left turn to the end of the revetment, right turn to the taxiway, right turn heading east on the taxiway, and then headed to the active runway. The big jet fighter handled OK-—it was a moose compared to the F-86. But what the hell, its gross weight was about 3 ½ tons more than the F-86. About 30 yards from the end of my taxiway the LA tower cleared me on to the runway. “Roger,” I said, as I lined up on the runway. Jesus! What’s their hurry? I noticed a crowd gathered around the railing of the production pilots’ lounge. Of course, the F-100 was new to everyone including the tower operators. “Don’t fuck up here, Simpson,” I said to myself. I checked the freedom of the controls, all instruments, and my flow of oxygen as I took the runway and lined up. I was soaking wet with sweat. I stomped on the brakes, added full military power, checked all my power gauges—RPM—EGT (exhaust gas temperature) oil pressure—fuel flow-flight controls once more, and then—let go!! All 12 and ½ tons of me!! I checked the airspeed indicator, made sure I had directional control with the nose gear steering as I moved down the runway, and then hit the afterburner. A 50th of a second later I was hit in the back with a big burst of significant forward pressure—literally throwing me against the back of the seat!! 15,000 horses! The F-100 accelerated. Fifty, seventy, ninety knots; I now had full directional control with the rudder—I was haulin’ ass. One hundred, one twenty five, one fifty—I eased the nose off—waited—then slowly added back pressure to the stick and at 175 knots my silver streak with the tailpipe of blinding intensity broke free from the grip of the runway and headed for blue skies. I put the gear handle in the ‘UP’ position, took the aircraft out of afterburner, trimmed the big bird, and the second I hit the coastline I turned 45 degrees and headed for 30,000 ft. at a point south and east of Catalina. I trimmed for pitch and roll again, and relaxed—a little bit. I made some small aileron inputs on the way—first right and then left then increased them bank-to-bank. I did a barrel roll. I performed wings-level side-slips. At 20,000 ft. I turned an additional 30 degrees toward San Diego and made throttle transients from idle to military power. The engine reaction was smooth and responsive. I did a couple of aileron rolls. Oops! A little yaw there? I looked around. At 30,000 feet I pushed the throttle into afterburner. My eyes were riveted to the Mach meter. At Mach .95, .96, the longitudinal stability was ‘edgy’. I didn’t like that. My inputs into the stick were minor. I looked around. The next thing I observed was the Mach needle indicating Mach 1.05, then 1.1, then 1.13. I was supersonic in level flight. “That’s enough,” I said to myself. I moved the throttle inward to come out of afterburner. Damn! Look at me; I’m almost to San Diego!! Turn around! Head back! It seemed as if I had the world by the ass—but I didn’t want it to crap all over me. I was confident. I sharply turned around toward the Palos Verdes peninsula. At the same time I cracked the speed brake, took notice of the trim change, corrected it with the trim switch on top of the stick. Remember my first combat mission when I tried to use it as a bomb release? Was I dumb or what? If someone had offered me a penny for my thoughts he would have had change coming.
I tried a power-on stall—with the gear up. It handled OK. Good aileron input and control—good response in pitch/throttle control too. I didn’t go less than 200 knots—just wanted to get a feel. Good elevator control—kept my altitude on the mark—well, almost! I did notice a pretty high angle of attack, though. I made a simulated landing—downwind, gear down-—poor directional control, simulated base and final. I needed power—lots of power—as my angle of attack increased. I simulated a go around. I got the airspeed to increase, pulled the gear, and flew in level flight. I said to myself, “That was a mess.”
I was lighter. I did a couple of aileron rolls left and right. Whoa!! Did I detect excessive yaw? I’m going to have to do that again, but I’d better head for home for now.
I extended the speed brake to max, let it take full effect, rolled over and headed for downwind at LA. I had plenty of fuel but I wasn’t about to run out if I had to make a go-around—or two! Naturally I was thinking what I had been told—“landing difficult and touchdown speed high.” LA International wasn’t exactly Edwards. And it didn’t make me feel any better when, just a few days before, “Wheaties” Welch tried to demonstrate a slow speed approach and hit short and banged the hell out of the tail cone of the engine and tail assembly of the aircraft.
Major Woolfolk made it OK but now it was my turn.
I called the tower and received permission to land on 25 Left. I started downwind at 1500 feet, held it steady with sufficient power, felt sweat running down the crack of my ass, lowered the gear, and turned base. Was I in for a surprise!! The gear seemed slow to come down and it wasn’t sequential. The left gear lowered and locked ‘DOWN’, but the right was slow and had not, as yet. The aircraft yawed left then right. I over corrected—had to fight the rudder pedals—as the right gear locked ‘DOWN’ as had the nose gear. The big moose’s reaction to the controls seemed to be in slow motion. “This is a *&%#@+|^ mess,” I said to myself. “Fighting a non-sequential gear with what seemed to be an ineffective vertical stabilizer and rudder. That’s bull shit.” It was my first real test with facing reality and I was going to ask Major Woolfolk about it. ‘Wheaties’ Welch was doing most of the initial flying and he didn’t say anything about it. Neither did Major Woolfolk. Maybe I should have dropped my gear on the downwind. But that’s bull shit too. The plane was still only under 1 ‘G’ conditions. North American was aware of a number of problems and I was sure they were doing something about them. Everyone was enthralled with a supersonic airplane. So was I—but I was right there at the plant and I had a boss who listened. I was flying #52-5756, the first F-100A-1, accepting it for the Air Force and I didn’t like what I was flying a single bit. Bob Kemp, the brilliant F-100 chief project engineer, would listen. Things settled down as I turned final. What was I going to do? Use power and have a high angle of attack or keep altitude as long as I could then have a swift, controlled crash. I took the power on approach. I felt beads of sweat dripping off my forehead. Two hundred knots, 190, 180, aiming for the “25L” on the runway. Lined up OK. Down—down—add power—down—nose up!! Too much!! Down—little power—OK!!—Easy—let ‘er down—170 knots-good lateral control—Keep it at 170---no less than 165! You look OK!! Nose up—easy!—easy!—pull back on the stick—the power—bleeding airspeed OK—easy! eeeeeezzzy!! That’s it!! Touchdown!! Power to idle—kiss the runway with the nose gear——not that hard!! Yah dumb jock! Brakes—just a touch—more—pull the drag chute—easy—easy—I felt the tug of the chute—a little brakes—let it roll—you’re slow enough—release the chute—more brakes—turn off next taxiway—careful with your taxi. I’m home! I made it!! I’m QUAD-S——Suitcase Simpson—Supersonic Shitkicker!! I was elated about my flight. Major Woolfolk and George Smith met me at the flight line. They shook hands with a body that should have flown in a wet suit. I would be lying if I said my first flight was effortless—or simple. It wasn’t! Was I apprehensive about the whole thing?? Definitely! I reported my comments to Major Woolfolk. He stated that North American was fixing the uneven ‘gear down’ problem with a set of priority valves in the utility hydraulic system and retrofit kits were being prepared for the test aircraft and the first few production models. In fact, he said, you knew you were in the first bird; in the next few weeks it will be taken care of. “You were right in telling me,” he said. “I won’t have the chance to fly as much as you will so I want to be told everything. You can put your signature on the DD-250 (the form that pays NAA.) It has been noted that the Engineering Change Proposal (ECP) will be in the form of a retrofit.” “Yes, Sir,” I said. “I will do that. I’d like to say something else. I rolled the aircraft—pretty good stick force into the aileron roll. After a couple of them I though I sensed more than normal yaw—certainly more than I have ever been associated with. “You’re right—long cigar fuselage and maybe not enough tail. Engineering is looking at that now. And Jack, don’t be afraid to speak up.” “Yes, Sir.” Major Woolfolk then said, “It’s Bill and Suitcase at the plant. Treat me like a Major when I’m in the company of pretty women.” “Gee, Bill,” I said. “By that time I’ll forget your name.” He laughed. Thank God!! He was one of the ‘good guys’ |
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