Phaethon666 102 Report post Posted September 29, 2015 (edited) IN THE COCKPIT PROFILE: F7F Tigercat (an untold story) BY Corky H. Meyer Flight Journal Magazine, August 2002, Volume 7, No. 4 “The relatively unknown Grumman Tigercat was the first production Navy fighter to better the performance and capabilities of land-based fighters. The two Grumman twin-engine fighter prototypes that preceded it, the Navy XF5F-1 Skyrocket and the Army Air Corps XP-50, were both designed and tested before the United States entered WW II, so they provided little or no background combat experience for the Tigercat design.” On June 26, 1942, the XF6F-3 Hellcat had just emerged from the Grumman experimental hangar in Plant One, so space became available for the many XF7F-1 (Grumman design 51) subassemblies that were coming in from the other Grumman Bethpage plants. I was not privy to the early months of the Tigercat’s design and construction because of my Hellcat test-flying commitment from December ’42 to July ’43. But in August 1943, I was ordered by Bob Hall, assistant chief engineer for the Experimental, to find a wooden box and literally sit next to the XF7F-1 prototype as it was being completed so that I could learn as much possible about its anatomy. This was the best possible spot anywhere in the United States for a 23 year old test pilot to obtain the equivalent of an advanced aeronautical degree. I was to learn about and have a say in many of the useful design decisions that were made during the three months I spent “in” my “box” seat. On October 23, 1943, I participated in engine runs, system checkouts and high-speed taxi tests. On November 2, Bob Hall lifted the Tigercat off the tarmac for a few feet and landed it. The next day, for its official first flight, Bob flew it for 20 minutes. He flew 4 more flights and then turned it over to me as project pilot. My first flight was November 10, 1943. At that time I had a total of 36 hours and 10 minutes twin-engine time in training aircraft, and they had less than 30% of the power of the twin-engine XF7F. This was very heady stuff for a J-3 Cub-trained test pilot. The noise of the two 2,000 HP Pratt & Whitney R-2800-10B engines just outside the thin canopy was most impressive. I never made a first flight that was as powerfully soul-stirring as the first flight I made in the XF7F-1 one day before my first anniversary at Grumman. Even my first flights in jets weren’t as memorable. It was mind-boggling to keep this eight-gun fighter in a 30-degree climb until it attained its service ceiling. In comparison, the soon-to-be-famous six-gun F6F-3 Hellcat fighter I had been testing suddenly seemed like and elderly pussycat. The XF7F-1 GETS A NAME Early in the XF7F-1 flight-test program, the flight-test group informally dubbed it “Tomcat.” The name seemed to fit a night fighter, so Grumman proffered it to the BuAer fighter desk in Washington D.C. and was surprised when the name was denied. The Navy letter stated, “The name ‘Tomcat’ is unacceptable. It denotes feline promiscuity.” Period; end of message. It did accept the second name “Tigercat” as not being as socially and politically unacceptable. Twenty-five years later, in a completely different cultural climate, the F-14’s Tomcat name went over the hurdles without a hitch. It may have been because the three top admirals in the Navy Air at the time were all named Tom: Moorer, Connely, and Walker! My FIRST “PENALTY” AIRSHOW On December 5, 1943, a group of Washington Navy brass came to Grumman’s Bethpage plant to discuss the progress of the XF7F-1 program and to see the plane demonstrated. It would be my 15th flight in the Tigercat, and I looked forward to the showing off this very powerful aircraft. I made a very short, flaps-down, full-power takeoff at 75mph; the aircraft climbed at an outrageous angle compared with the production Hellcat that had taken off just before me. I picked up speed and came in for a 400 mph-plus, low-level pass. As I approached the end of the runway at treetop level, I suddenly saw the Beau Sejour restaurant flag pole and its waving flag directly in front of me about 30 feet higher than my altitude! To go over it, I pulled up quickly; this required an abrupt pushover to get back to the runway in time for a low-level pass. After passing the admiral’s group in the tower, I made a 5G pull-up to start a Cuban-8 loop. When I was vertical, a call from the tower said that Flight 2 (Bud Gillies, vice president of Flight Operations) wanted to see me in his office immediately after landing. Sensing what might be in store for me, I made a slow-speed overhead pass in the carrier-approach condition and followed this with a very slow carrier-type landing and a quick trip to his office. I didn’t know what I had done to warrant the summons, but it soon became apparent that Bud, who was not slow with his thoughts, was madder than a hornet. He said that I had been reckless with the experimental aircraft because, from the view from the tower, it first looked as though I would hit the flagpole, which was followed by a seemingly abrupt diving crash into the runway. After a much too long, one-way conversation, he told me I would be given a week off without pay—beginning immediately! End of conference. I was later told that his voice could be heard over the low office partitions from one end of Plant One to the other. Gillies also notified me that I would spend the week off writing the complete Tigercat Pilot Handbook. The possibility of being fired was much more frightening than a mere one-week’s salary loss. XF7F-1 GOES INTO PRODUCTION Wartime priorities for aircraft production were such that the XF6F-1 Hellcat and the XF-7F-1 Tigercat were ordered into production by the Navy on the same day, May 14, 1941, but by the first flight date of the XF7F-1 18 months later, Grumman had delivered more than 4,500 Hellcats to the combat zones! The first experimental XF7F-1 Tigercat had the 2,000 HP Pratt & Whitney R-2800-10B engine. This was the Hellcat’s standard production engine, and it continued Grumman’s policy of not installing an untried engine in a new aircraft. The Tigercat, which was 71mph faster than the Hellcat and had twice its rate of climb, easily met the Navy’s requirements of 451mph at 21,000. With the Tigercat’s excellent performance and flight characteristics demonstrated, the Navy decided that, despite the fighter’s minimum controllability and sing-engine-failure takeoff speed (40mph more than the Navy requirement), it should go into production as soon as possible. Understand that, in early 1944, the War in the Pacific was far from over, so maximum production numbers were mandatory. After his four flights in November 1943, Bob Hall ordered the fin to be enlarged 292 percent to meet the single engine criterion. But such a significant change could not be designed, ground and flight-tested, and then implemented in the production line until the 106th Tigercat F7F-3N BuNo 80365 was delivered in July 1945—two and a half years after the problem became apparent! The first production Tigercat, BuNo 80259, which was to be the structural demonstration aircraft, was sent to NAS Mustin Field in Philadelphia from April 13, to 19, 1944 for the early carrier suitability tests. It had a new Y-frame tailhook configuration. That hook failed its tests; the Navy required a fully swiveling tailhook. These trials had a very interesting effect on the structural demonstrations that immediately followed these tests. NAVY STRUCTURAL, AERODYNAMIC, SPIN & POWERPLANT DEMOS BEGIN In wartime, the structural demonstration of any fighter is first on the list; the hope is that no major structural redesign changes will have to be retrofitted on a fast-moving production line. The structural program for a7.5 G-limit load and 525mph-limit speed were trouble-free until I began to speed buildup above 460mph. As speed built up, the aircraft began to oscillate up and down longitudinally plus and minus ½G with increasing frequency and amplitude as the speed increased. This had never happened before in any other Grumman fighter; it was unnerving, but tolerable. Our aerodynamic engineer said that these were probably Mach-number effects and I shouldn’t worry about them. I completed the 525mph-speed point with a galloping 2.5G pullout and then flew the aircraft to Patuxent to repeat the demonstration for the Navy. During the final 525mph pullout, the pilot of my chase Tigercat F7F-1 BuNo 80265, Cdr. Don Runyon, said that he didn’t experience any oscillations while flying close formation with me throughout the dive! When I returned to Grumman, I again asked the structural engineers why my Tigercat oscillated and the Patuxent chase F7F-1 didn’t. They rechecked all of the aircraft’s major dimensions and found that my Tigercat’s tail had been 2 degrees out of alignment, probably during the off-center carrier landing tests at Mustin Field that put the highest torsional loads on the fuselage. The tail was forced back to its proper dimensions, and the plane flew without Oscillating! I learned a great lesson: never believe engineering’s first answers as “found gold.” TIGERCAT DOESN’T ENJOY SPINNING THE NORMAL Navy SR-38D spin-demonstration requirement was five turns in both directions, both from the upright and from inverted entries. Experimental military aircraft usually have a standard 10-foot anti-spin parachute that can be deployed on a 50-foot lanyard from the aft end of the fuselage if the demonstrating pilot finds himself in an unrecoverable spin. The drag of this small experimental-use-only parachute will stop the spin so that a normal recovery can be made. I was the first—and fortunately, the last—test pilot to investigate twin-engine Naval fighter aircraft spins. I had successfully spun and recovered from the production F4F-4 Wildcat and F6F-3 Hellcat to 10 turns. Engineering did not consider the experimental anti-spin chute necessary for the Tigercat because of the powerful thrust of an offset engine in a twin-engine aircraft, which aids in spin recovery. Bob hall strongly suggested that I proceed very slowly in the building up the number of spin turns prior to recovery and to increase only a half turn at a time before attempting recovery. His wisdom was soon to be greatly appreciated. Let the spins begin. The first half-turn spin attempt seemed to have sluggish half-turn recovery to anti-spin control reactions. After a one-turn spin, it took one whole turn to recover with full anti-spin controls. An alarm went off in my head because, after one- to four-turn spins, the Hellcat and Wildcat recovered immediately when their controls were released. Even after 10 turns, those aircraft took only one turn for recovery. At one and a half turns from right- or left-spin entries, the F7F’s nose tended to rise during the last portion of the spin, and it took an all-too-long one and a half turns for recovery after “instant” full anti-spin control application. The continued need for an equal number of turns of turns to recover from the same number of spins turns sounded a much louder alarm bell. I should have quit then and there, but being inexperienced, I completed two-turn spins. They required two slow turns for recovery. The nose was definitely rising toward a flat, uncontrollable spin in the second turn before recovery controls were applied. The two turns required for recovery seemed to take ages. I became very concerned about this new aircraft’s spin-recovery lethargy, so I returned to base to talk to the engineers and Bob Hall, who had done many more experimental-aircraft spins that I. I also wanted the center of gravity to be checked for accuracy. I hoped that the engineers might find that it was inadvertently too far aft; this would have causes such a delated spin-recovery reaction. The center of gravity was found to be accurate, and the full-recovery control deflections checked out OK, too. The engineers suggested that maybe the large inertial mass of the engines caused the spin to flatten and result in a sluggish recovery. One of the engineers suggested that we check the Tigercat NACA spin tunnel model report! I had never heard about a NACA spin tunnel or of such a report on the Tigercat’s spinning tendencies; my education was expanding. That report detailed how the model F7F-1 tunnel spin indeed showed the nose rising in the first few turns and going flat and the plane becoming unrecoverable after four turns. Bob Hall decreed that we stop at two turns. He then promptly discussed the problem with the Navy and got the Tigercat requirement—to my great relief—limited to only a two-turn, upright spin. Because of the long and sluggish recovery cycle, the Navy stated in the pilots’ handbook, “All spins and snap rolls are prohibited maneuvers in F7F aircraft.” In spite of the warning, a few weeks later, a military test pilot at Patuxent decided to try spinning a Tigercat. As predicted in the wind-tunnel report, the plane went flat at the fourth turn, and it continued to spin for 200 more unrecoverable turns until it hit the ground, killing the plot instantly. This experience caused me to heed the NACA spin-tunnel findings for all of the many other experimental Grumman fighters that I tested. MEYER’S NAVY “EVALUATION” Instead of delving into the details of the fantastic handling characteristics of the Tigercat, I will tell you of a totally unexpected and earth-shaking discussion that I had with the Navy’s premier test pilot, Capt. Fred M. Trapnell. It will explain why all Tigercat pilots liked the airplane in spite of its failure to meet several important Navy SR-38D specifications for flight-handling characteristics. For many years, Capt. Trapnell was a top test pilot in the Navy; his word was law, both in Navy and Industry flight-test circles. An example of his influence: he came for a three-hour flight evaluation of the first XF6F-# Hellcat soon after its first flight and he gave the official Navy go-ahead for mass production on that day! The Hellcat eventually passed all of its contractual demonstrations two and a half years later, after more than 8,000 aircraft had been delivered to fighting squadrons! Also, to his credit, the Hellcat racked up a record 19 to one kill-to-loss ratio—the highest recorded in WW II. When he came to Grumman to conduct the preliminary evaluation of the Panther in early 1948, I was the only Grumman test pilot who had flown the company’s first jet fighter. At every opportunity during his three-day evaluation, I tried to pry his opinions out of him; his only responses were grunts, which I interpreted as, “Coot it, Corky!” At the end of his evaluation, as we walked out to his F7F-4N Tigercat for his return trip to the Naval Air Test Center, I proudly told him that I was the Tigercat project pilot from 1943 to 1946. He immediately burst into a diatribe about the Tigercats’s many deficiencies: the over-cooling of the engines; a lack of longitudinal stability; excessively high dihedral rolling effect with rudder input; the high minimum single engine control speed, etc. He ended his oration with: “If I had been the chief of the Test Center at that time, I would have had you fired!” Each criticism of the Tigercat was absolutely correct. I was devastated and fervently wished that I hadn’t gotten out of bed that day. Just as we reached his Tigercat, I blurted, “If you dislike the Tigercat so much, why do you always fly it?” He explained: “The excess power of its two engines is wonderful for aerobatics; the cockpit planning and the forward visibility in the carrier approach is the best in any fighter ever built; the tricycle landing gear allows much faster pilot checkouts; the roll with the power boost rudder is faster than the ailerons; and it has a greater range than any fighter in inventory.” Again he was absolutely right. As he climbed into the cockpit, he turned around, grinned and told me, “It’s the best damn fighter I’ve ever flown.” I realized he had thrown the entire test-pilot schoolbook at me with his succinct tirade and that we were probably pretty close in opinions regarding the handling characteristics that define a really good fighter. I went home happy that night. His report on the Panther cited only one minor easily fixable, hydraulic-system deficiency that I had not noted. TIGERCAT TRANSONIC TRIBULATIONS The Tigercat was a very slick, quickly accelerating aircraft. Its full-power dive-limit could be attained at 35-40 degree dive angles in less than 30 seconds. Its great weight and twin-engine power made it by far the slickest accelerating prop fighter I ever flew (This comparison includes the famed F8F-1 Bearcat). In October 1944, during the joint Army/Navy Fighter Confrence at the Naval Air Test Center at Patuxent, Maryland, many test pilots were introduced to the NACA-developed dive recovery flaps on the P-47 Thunderbolt and Lockheed P-38J Lightning. They were introduced to the cockpit Mach number instraments that tell the pilot the percentage of the speed of sound at which that aircraft is traveling. (Dr. Ernst Mach was an Austrian physicist who studied the shock-wave phenomena generated at the speed of sound by way of artillery firing tests in the late 1800s.) Before the Fighter Conference, all test flights made beyond critical (and uncontrollable) Mach number of a fighter were made “by guess and by God” The several compressibility dives that I did in the Hellcat went far into the unknown. And a pilot such as me didn’t then have a Mach meter to tell him when he was about to enter the unknown until he was riding—not flying—a totally uncontrollable airplane in a steep dive. I took the opportunity to fly both P-47 and the P-38 to evaluate the dive-recovery flaps and the Mach meter—two great, life-saving additions in fighters that made it possible for them to be safey flown and recovered at speeds beyond their critical Mach numbers. It was decided that the Tigercat dive-recovery flaps would be installed between the fuselage and the engine nacelles on the underside of the wing and 30 percent behind the leading edge. Engineers selected this because they wanted to ensure a maximum effect on the downwash angle of the Tigercat’s stabilizer for the automatic pullout they would provide. As a safety precaution, on my first compressibility test of the dive in F7F-3 BuNo 80330 on October 9, 1946 I started from a 40-degree dive angle at 35,000 feet, aiming to penetrate the violent buffeting of the compressibility area as high as possible. This would keep air-density flight loads as low as they could be. When I exceeded 0.72 Mach, the controls were instantly frozen solid by compressibility effects, so I promptly extended the dive-recovery flaps. The airplane immediately rotated up to 5G and went wild. It yawed back and forth by 10 to 15 degrees, started a roll oscillation, began to porpoise between 4G and 6G and buffeted violently. What I thought would be a smooth, run-of-the-mill test flight turned out to be one of the most hair-raising events of my career. Fifteen long seconds later, when the Tigercat had decelerated to below 0.72 Mach, The shock-wave compressibility effect disappeared, and normal aircraft control returned. The maximum Mach number recorded was 0.78. After landing, the instrumentation showed the details of the flight described above; when I extended the dive-recovery flaps, the aircraft structure had extended its load limit in several fuselage and tale areas, and all hell had broken loose. Fortunately, an airframe inspection didn’t find any pulled rivets or skin wrinkling. It was very clear to all, however that the venture effect between the fuselage and nacelles made this dive-recovery-flaps position grossly unacceptable and possibly damaging. P-38’s dive recovery flaps were outboard of the engine nacelles, so Grumman engineering then decided to put the Tigercat’s there, too. At that location, the Tigercat did transonic compressibility pullouts as smoothly as the P-38 and P-47 had. After some minor adjustments to the dive-recovery brake angle a smooth hands off 4G recovery could be made when the Tigercat was deep into its vertical. Compressibility terminal-velocity speed of 0.805 Mach. This Mach number at 20,000 feet was a little more than 600mph true airspeed. I presumed that the dive-recovery flaps were never retrofitted to the Tigercat because the war was over and the Tigercat production was soon terminated. The Tigercat did, however, get the new two handed airspeed indicator with the second hand that showed the 0.72 Mach airspeed limit beyond which the aircraft would enter compressibility. That feature, plus my strong admonitions in the Tigercat’s pilot’s handbook, dissuaded pilots from ever entering a compressibility flight. The Tigercat’s fabulous dive speed acceleration could at last be tamed by pilots. CONCLUSSION Because the Tigercat’s Navy production priority was lower than that of the Hellcats, it was not given the opportunity to demonstrate its magnificently lethal air-to-air, air-to-ground and air-to-ship (torpedo) capabilities in WW II. It did play an important role in the Korean War, but by that time, Jet-powered Grumman Panthers had begun to demonstrate a greatly superior combat performance potential. A total of 364 Tigercats in seven models were produced between October 1943 and November 1946. Because of its outstanding performance, handling characteristics, and reliable engines and instant pilot acceptance, it had an exceptional safety record for such and advanced and powerful fighter. Its growing pains with WW II carriers (Will include sidebar later about Carriers *Phaethon666)) paved the way for the many larger tricycle-landing-gear jet fighters and bombers needed for the post-WW II carriers during the Vietnam War. For this reason, the Tigercat deserves to be better remembered. The Pilots who were fortunate enough to fly the Tigercat recall their love affair with it and remember it as the most thoroughly exciting and most easily tamed warhorse they even rode through the skies Edited September 29, 2015 by Phaethon666 3 Share this post Link to post Share on other sites More sharing options...
Bringo_Gaboso 3,820 Report post Posted September 29, 2015 pic to liven the post up ! 1 Share this post Link to post Share on other sites More sharing options...
Phaethon666 102 Report post Posted September 29, 2015 pic to liven the post up ! Thanks Bringo, I believe that is BuNo 03549! Share this post Link to post Share on other sites More sharing options...
