Sikorsky S-72 RSRA 72001 in initial configuration. (Sikorsky, a Lockheed Martin Company)
12 October 1976: The Sikorsky S-72 Rotor Systems Research Aircraft (RSRA) made its first flight at Stratford, Connecticut. The S-72 was a hybrid aircraft built for the United States Army and the National Aeronautics and Space Administration. Its purpose was to serve as a flight test vehicle for various helicopter rotor configurations.
The S-72 was three-place, four-engine, single main rotor/tail rotor compound helicopter with retractable main landing gear. The flight crew consisted of two test pilots in a side-by-side cockpit, and a flight test engineer in the cabin. The left pilot’s position was equipped with “fly-by-wire” flight controls, while the right seat used conventional mechanical controls as a safety back up. The S-72 had a crew escape system, which blew the main rotor blades off, allowing the crew to land the aircraft in its airplane mode, or to be extracted by rockets.
The aircraft was built with a low-drag fuselage capable of reaching 340 knots (391 miles per hour/630 kilometers per hour) and used the rotors and drive train of the S-61 Sea King. A wing and two turbofan engines allowed the aircraft to fly as an airplane.
Sikorsky S-72 N740NA in flight near Edwards Air Force Base, California, without a main rotor, circa 1984. (NASA)
The S-72 had an overall length with rotors turning, of 75 feet, 11 inches (23.139 meters). The fuselage had a length of 63 feet, 8 inches (19.406 meters), and maximum width of 8 feet, 4 inches (2.642 meters). The RSRA had an overall height of 15 feet, 6 inches (4.724 meters). The variable incidence wing has a span of 45 feet, 1.2 inches (13.746 meters). The angle of incidence could be varied in flight from +15° to -9°. The span of the horizontal stabilizer is 20 feet, 10 inches (6.350 meters). The S-72 compound helicopter had an empty weight of 20,812 pounds (9,440 kilograms) and gross weight of 26,392 pounds (11,971 kilograms). When stripped to a pure helicopter configuration, the empty weight was reduced to 14,490 pounds (6.573 kilograms).
The S-72 was first flown using the rotors from the S-61. These were later to be replaced with experimental rotor systems. The S-61 main rotor has five blades and a diameter of 62 feet, 0 inches (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The main rotor turns at 203 r.p.m., counter-clockwise, as seen from above. (The advancing blade is on the right.) The S-72’s tail rotor also has five blades and has a diameter of 10 feet, 7.25 inches (3.232 meters). The blades have a chord of 7–11/32 inches (0.187 meters). The tail rotor turns clockwise as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.) The tail rotor turns 1,244 r.p.m.
General arrangement with dimensions. (Sikorsky Historical Archives)
The S-72 was powered by two General Electric T58-GE-5 turboshaft engines, driving the rotor system, and two General Electric TF34-GE-2 turbofan engines providing thrust for flight in the airplane or compound helicopter configuration.
The T58-GE-5 turboshaft engines are the same engines that powered the HH-3E Jolly Green Giant combat search and rescue helicopters. They are a free-turbine turboshaft with a 10-stage axial-flow compressor section a 2-stage gas generator turbine (N1) and 1-stage free power turbine (N2). The T58-GE-5 has a Maximum Continuous Power rating of 1,400 shaft horsepower, each, and Military Power rating of 1,500 shaft horsepower. The engine is 59.0 inches (1.499 meters) long, 20.9 inches (0.531 meters) in diameter, and weighs 335 pounds (152 kilograms).
The TF34-GE-2 turbofan was developed for the U.S. Navy’s Lockheed S-3A Viking anti-submarine aircraft. It was a two-spool axial-flow jet engine with a single-stage fan section, 14-stage compressor, and 6-stage turbine section (2 high- and 4 low-pressure stages). The TF34-GE-2 was rated at 9,275 pounds of thrust (41.26 kilonewtons).
The S-72 had a maximum speed in level flight of 300 knots (345 miles per hour/556 kilometers per hour), and 340 knots (391 miles per hour/630 kilometers per hour) in a dive.
Two RSRAs were built. After Sikorsky’s flight test program was completed in 1979, the two RSRA aircraft were delivered to NASA Ames. The Aircraft received civil registrations N740NA (72001) and N741NA (72002).
The stripped airframe of the first Sikorsky S-72, 72001, sits behind a chain link fence at Fort Rucker, Alabama.
Jackie Cochran with her record-setting Northrop T-38A-30-NO Talon, 60-0551, at Edwards Air Force Base, 1961. (U.S. Air Force)
12 October 1961: From August to October 1961, Jackie Cochran, a consultant to Northrop Corporation, set a series of speed, distance and altitude records while flying a Northrop T-38A-30-NO Talon supersonic trainer, serial number 60-0551. On the final day of the record series, she set two Fédération Aéronautique Internationale (FAI) world records, taking the T-38 to altitudes of 16,841 meters (55,253 feet) in horizontal flight ¹ and reaching a peak altitude of 17,091 meters (56,073 feet). ²
Jacqueline Cochran’s Diplôme de Record in the San Diego Air and Space Museum Archives. (Bryan R. Swopes)Jacqueline Cochran’s Diplôme de Record in the San Diego Air and Space Museum Archives. (Bryan R. Swopes)Northrop T-38A-30-NO Talon 60-0551 at Edwards Air Force Base, California. (U.S. Air Force)
Famed U.S. Air Force test pilot Chuck Yeager, a close friend of Jackie Cochran, kept notes during the record series:
October 12 Jackie took off at 9 am in the T-38 using afterburner. Bud Anderson and I chased her in the F-100. It was an excellent flight with everything working perfect. Jackie entered the course at 55,800 feet at .93 Mach and accelerated to radar. At the end of the run Jackie pulled up to 56,800 and then pushed over. She cut the right afterburner at 52,000 feet and the left one at 50,000. At 12,000 feet she removed the face piece from her pressure suit and made a perfect landing on the lake bed.
Northrop-Air (Norair) presented Miss Cochran with one dozen yellow roses.
A very tender ending to a wonderful program and a fitting token to a wonderful lady—a pilot who gave Norair much more than they expected.
— Brigadier General Charles Elwood (“Chuck”) Yeager, U.S. Air Force, quoted in Jackie Cochran: An Autobiography, by Jacqueline Cochran and Maryann Bucknum Brinley, Bantam Books, New York, 1987, Pages 307–308.
Jackie Cochran and Chuck Yeager at Edwards Air Force Base, California, after a flight in the record-setting Northrop T-38A Talon. (U.S. Air Force)
The T-38A is a two-seat, twin-engine jet trainer capable of supersonic speed. It is powered by two General Electric J85-5A turbojet engines producing 2,050 pounds of thrust (3,850 with afterburner). Jackie Cochran demonstrated its maximum speed, Mach 1.3. It has a service ceiling of 50,000 feet (15,240 meters) and a range of 1,140 miles (1,835 kilometers). In production from 1961 to 1972, Northrop has produced nearly 1,200 T-38s. It remains in service with the U.S. Air Force, U.S. Navy, and the National Aeronautics and Space Administration.
Jackie Cochran’s record-setting T-38 is in the collection of the Smithsonian Institution, National Air and Space Museum.
Jackie Cochran’s record-setting Northrop T-38A-30-NO Talon, 60-0551, on display at the Smithsonian Institution, Steven F. Udvar-Hazy Center. The Talon is in the markings of the Sacramento Air Logistics Center, McClellan Air Force Base, Sacramento, California. (NASM)
North American Aviation’s Chief Engineering Test Pilot, George S. Welch, with the first prototype YF-100A Super Sabre, 52-5754. (U.S. Air Force)
12 October 1954: North American Aviation Chief Engineering Test Pilot George S. Welch, testing the ninth production F-100A-1-NA Super Sabre, serial number 52-5764, made a planned 7.3 G pullout from a Mach 1.55 dive to verify the aircraft’s design limits.
A Boeing B-47 Stratojet crew flying at 25,000 feet (7,620 meters) reported that Welch’s F-100 winged over and began a rapid descent, passing within four miles (6.4 kilometers) of their position and diving at a very high speed. The aircraft appeared to be under control but then suddenly disintegrated.
The Super Sabre had encountered Inertial Roll Coupling. It went out of control and then disintegrated. Its nose folded over the windshield, crushing Welch in his seat. The vertical fin broke away. The ejection seat fired but because of the supersonic speeds the parachute was shredded.
Welch was still alive when rescue teams arrived. He died while being flown to a hospital by helicopter.
George S. Welch, North American Aviation test pilot, wearing his orange flight helmet. An F-86 Sabre is in the background. (San Diego Air and Space Museum Photo Archives)
Inertial roll coupling led to the death of test pilot Mel Apt when his rocket-powered airplane, the Bell X-2, went out of control at Mach 3.2 It nearly killed Chuck Yeager when he lost control of the Bell X-1B at Mach 2.4. It is a complex phenomenon which I will briefly attempt to explain:
To increase maximum speed of transonic and supersonic airplanes during the late 1940s and early 1950s, their wings and tail surfaces were made smaller in order to decrease aerodynamic drag. At the same time, the fuselage became longer and the placement of engines, armament, landing gear, fuel, etc., within the fuselage concentrated the airplane’s mass near its center. While the gyroscopic effects of the turbojet engine contributed some degree of longitudinal stability, the torque effect made rolls to the left occur more easily, but with a higher rate than a roll to the right. The resistance to a change in attitude—inertia—decreased at the same time that the control surfaces’ ability to control the airplanes’ attitude also decreased. The airplanes became unstable.
This North American Aviation F-100-1-NA Super Sabre, 52-5761, is from the same production block as the aircraft flown by George Welch, 12 October 1954. This photograph shows FW-761 with the original short vertical fin of the F-100A. (North American Aviation, Inc.)North American Aviation F-100A-1-NA Super Sabre 52-5763, sister ship of the airplane flown by George Welch, 12 October 1954. (North American Aviation, Inc.)
When George Welch tried to pull the F-100 out of its supersonic dive, the airplane’s speed began to decrease as the angle of attack increased. The wings’ ability to stabilize the natural roll instability of the fuselage’s concentrated mass was lessened, and the ailerons could not provide sufficient control to counteract this rolling tendency. The low vertical fin of the original F-100A did not provide adequate directional stability. The Super Sabre rolled and then yawed, entering a side slip. This caused the Super Sabre to pitch down and it was suddenly out of control in all three axes. The physical forces exceeded the strength of the aircraft structure and it came apart.¹
[Aerodynamicists and Aeronautical Engineers: Your corrective comments are welcome.]
Wreckage of North American Aviation F-100A-1-NA Super Sabre 52-5764, 12 October 1954. (North American Aviation, Inc.)
Following the death of George Welch, NACA High Speed Flight Station research test pilot Albert Scott Crossfield spent three months conducting flight tests of the F-100A, demonstrating its inertial roll coupling characteristics using three different vertical fins. F-100A-5-NA 52-5778 was Crossfield’s test aircraft.
Test Pilot A. Scott Crossfield flew this F-100A-5-NA, 52-5778, in flight testing at the NACA High Speed Flight Station, October–December 1954. (NASA)
The North American Aviation F-100 Super Sabre was designed as a supersonic day fighter. Initially intended as an improved F-86D and F-86E, the “Sabre 45” soon developed into an almost completely new airplane. The Super Sabre had a 49° 2′ sweep to the leading edges of the wings and horizontal stabilizer. The total wing area was 385.2 square feet (35.79 square meters). The wings had an angle of incidence of 0°, with no twist or dihedral. The ailerons were placed inboard on the wings and there were no flaps, resulting in a high stall speed in landing configuration. The horizontal stabilizer was moved to the bottom of the fuselage to keep it out of the turbulence created by the wings at high angles of attack. The F-100A had a distinctively shorter vertical fin than the YF-100A. The upper segment of the vertical fin was swept 49° 43′.
There were two service test prototypes, designated YF-100A, followed by the production F-100A series. The first ten production aircraft (all of the Block 1 variants) were used in the flight testing program.
The F-100A Super Sabre was 47 feet, 1¼ inches (14.357 meters) long with a wingspan of 36 feet, 6 inches (11.125 meters). With the shorter vertical fin, the initial F-100As had an overall height of 13 feet, 4 inches (4.064 meters), 11 inches (27.9 centimeters) less than the YF-100A.
Following Welch’s accident, the NACA High Speed Flight Station tested the Super Sabre and designed a new vertical fin for the F-100A. The two F-100As in this photograph are both from the second production block (F-100A-5-NA). 52-5778, on the left, has the new fin, while 52-5773 retains the original short fin. The new fin is taller but also has a longer chord. This resulted in a 10% increase in area. (NASA)
The F-100A had an empty weight of 18,135 pounds (8,226 kilograms), and its maximum takeoff weight was 28,971 pounds (13,141 kilograms). It had an internal fuel capacity of 744 gallons (2,816 liters) and could carry two 275 gallon (1,041 liter) external fuel tanks.
The early F-100As were powered by a Pratt & Whitney Turbo Wasp J57-P-7 afterburning turbojet engine. The J57 was a two-spool axial-flow turbojet which had a 16-stage compressor section (9 low- and 7 high-pressure stages) and a 3-stage turbine (2 high- and 1 low-pressure stages). Its continuous power rating was 8,000 pounds of thrust (35.586 kilonewtons). The Military Power rating was 9,700 pounds (43.148 kilonewtons) (30-minute limit). Maximum power was 14,800 pounds (43.148 kilonewtons) with afterburner (5-minute limit). The engine was 20 feet, 9.7 inches (6.342 meters) long, 3 feet, 3.9 inches (1.014 meters) in diameter, and weighed 5,075 pounds (2,303 kilograms). Later production aircraft used a J57-P-39 engine.
The Super Sabre was the first U.S. Air Force fighter capable of supersonic speed in level flight. It could reach 760 miles per hour (1,223 kilometers) at Sea Level. (Mach 1 is 761.1 miles per hour at Sea Level, 1,224.9 kilometers per hour, under Standard Atmospheric Conditions.) The maximum speed of the F-100A was 759 knots (873 miles per hour/1,406 kilometers per hour)—Mach 1.32—at 35,000 feet (10,668 meters). Its service ceiling was 47,500 feet (14,478 meters). The fighter’s combat radius was 402 nautical miles (463 statute miles/745 kilometers). The maximum ferry range with external fuel was 1,124 nautical miles (1,493 statute miles/2,082 kilometers).
The F-100 was armed with four M-39 20 mm autocannons, capable of firing at a rate of 1,500 rounds per minute. The ammunition capacity of the F-100 was 200 rounds per gun.
North American Aviation built 199 F-100A Super Sabres at its Inglewood, California, plant before production shifted to the F-100C fighter bomber variant. Approximately 25% of all F-100As were lost in accidents.
This is the fifth production F-100A-1-NA Super Sabre, 52-5760, in flight southeast of San Bernardino, California, 24 June 1955. This fighter is from the same production block as 52-5764, the fighter being tested by George Welch, 12 October 1954. In this photograph, FW-760 has the taller vertical fin that was designed by NACA to improve the Super Sabre’s stability. (North American Aviation, Inc.)
George Welch was born George Lewis Schwartz, Jr., in Wilmington, Delaware, 10 May 1918. He was the first of two sons of George Lewis Schwartz, a chemist at the Dupont Experimental Station in Wilmington, and Julia Welch Schwartz. His parents changed his surname to Welch, his mother’s maiden name, so that he would not be effected by the anti-German prejudice that was widespread in America following World War I.
He studied mechanical engineering at Purdue University, Indiana, and enlisted in the Army Air Corps in 1939. Welch graduated from pilot training at Kelly Field, Texas, and on 4 October 1940, was commissioned as a second lieutenant, U.S. Army Air Corps.
Second Lieutenant Kenneth M. Taylor and Second Lieutenant George S. Welch, 47th Pursuit Squadron, 15th Pursuit Group, the two Curtiss P-40B Warhawk pilots who shot down 8 Japanese aircraft during the attack on Pearl Harbor, Hawaii, 7 December 1941. Both officers were awarded the Distinguished Service Cross. (U.S. Air Force)
George S. Welch is best remembered as one of the heroes of Pearl Harbor. He, along with Second Lieutenant Kenneth M. Taylor, were the only two fighter pilots to get airborne from Haleiwa Auxiliary Airfield during the Japanese surprise attack on Hawaii, 7 December 1941. Flying a Curtiss P-40B Warhawk, he shot down three Aichi D3A “Val” dive bombers and one Mitsubishi A6M2 Zero fighter. Taylor also shot down four Japanese airplanes. For this action, Lieutenant General Henry H. “Hap” Arnold recommended the Medal of Honor, but because Lieutenants Welch and Taylor had taken off without orders, an officer in their chain of command refused to endorse the nomination. Both fighter pilots were awarded the Distinguished Service Cross.
During the War, Welch flew the Bell P-39 Airacobra and Lockheed P-38 Lightning on 348 combat missions. He had 16 confirmed aerial victories over Japanese airplanes and rose to the rank of Major. In addition to the Distinguished Service Cross, George Welch was awarded the Silver Star, the Distinguished Flying Cross with two oak leaf clusters (three awards), the Air Medal with one oak leaf cluster (two awards), the Presidential Unit Citation with two oak leaf clusters (three awards), American Defense Service medal with one service star, American Campaign Medal, Asiatic-Pacific Campaign Medal with one silver and one bronze star (six campaigns), and the World War II Victory Medal.
George Welch, circa 1943. (Unattributed)
Welch received the nickname, “Wheaties,” because he was the first military officer to be featured on a box of Wheaties cereal. (Wheaties, “The Breakfast of Champions,” was a toasted wheat bran cereal produced by General Mills. It normally featured champion athletes on its distinctive orange-colored boxes.)
Suffering from malaria, George Welch was out of combat and recuperating in Australia. There he met Miss Janette Alice Williams and they were soon married. Welch returned to the United States with his new wife. They had a son, Giles, born in October 1947. Their home was in Brentwood, California.
North American Aviation approached General Arnold to recommend a fighter pilot who could bring his combat experience to testing new fighters. Welch was one of two that General Arnold suggested. The general authorized Welch’s release from active duty so that he could join North American. Welch held the rank of major, Air Reserve, from 13 November 1944 to 1 April 1953.
George S. Welch, now a civilian test pilot for North American Aviation, Inc., sits on the canopy rail of a P-51H Mustang, circa 1945. (North American Aviation Inc.)
Welch went on to test fly the North American P-51H Mustang, FJ-1 Fury, F-86 Sabre and F-100 Super Sabre.
George Welch made the first flight of the XP-86 prototype, 1 October 1947. There is some evidence that on that flight, and during a subsequent flight on 14 October, Welch exceeded the speed of sound while in a dive. It has been said that during the Korean War, while teaching U.S. Air Force pilots how to best use the F-86 Sabre, he shot down several enemy MiG-15 jet fighters.
George S. Welch is buried at the Arlington National Cemetery, Section 6, Site 8578-D.
¹ Recommended: Coupling Dynamics in Aircraft: A Historical Perspective, by Richard E. Day, Dryden Flight Research Center, Edwards AFB, California. NASA Special Publications 532, 1997.
1st Lieutenant Chuck Yeager. (American Air Museum in Britain)
12 October 1944: During World War II, First Lieutenant Charles Elwood Yeager, Air Corps, Army of the United States (A.U.S.), was a P-51 Mustang fighter pilot assigned to the 363d Fighter Squadron, 357th Fighter Group, stationed at RAF Leiston (USAAF Station 373), near the village of Theberton, Suffolk, England.
Recently promoted from the warrant rank of Flight Officer, Lieutenant Yeager—as one of the most experienced pilots in the group— was leading the 357th on a bomber escort mission against Bremen, Germany. While the Group’s 362nd and 364th Fighter Squadrons remained with the B-24 bombers, Yeager and the 363d patrolled 50 to 100 miles (80 to 160 kilometers) ahead.
At 25,000 feet (7,620 meters) over Steinhuder Meer, northwest of Hanover, Yeager sighted a group of Messerschmitt Bf 109 fighters (also called the Me 109). He was soon able to count 22. Yeager and his squadron of 16 Mustangs circled and attacked out of the sun.
A flight of three Luftwaffe Messerschmitt Me 109 fighters, 20 July 1944. (Bundsarchive Bild 101l-676-7975-36)
As Chuck Yeager maneuvered his P-51D Mustang, named Glamorous Glenn II, to fire at a trailing Bf 109, the German fighter suddenly turned left and collided with his wingman. Both pilots bailed out of their fighters and the two Bf 109s went down.
“It was almost comic, scoring two quick victories without firing a shot. . . By now, all the airplanes in the sky had dropped their wing tanks and were spinning and diving in a wild, wide-open dogfight. I blew up a 109 from six hundred yards—my third victory—when I turned to see another angling in behind me. Man I pulled back the throttle so damned hard I nearly stalled, rolled up and over, came in behind and under him, kicking right rudder and simultaneously firing. I was directly underneath the guy, less than fifty feet, and I opened up that 109 as if it were a can of Spam. That made four. A moment later, I waxed a guy’s fanny in a steep dive; I pulled up at about 1,000 feet; he went straight into the ground.”
— Yeager, An Autobiography, by Chuck Yeager and Leo Janos, Bantam Books, New York, 1985, at Page 57.
1st Lieutenant Charles E. Yeager with “Glamorous Glenn II,” at USAAF Station 157, Raydon, Suffolk, England, 17 October 1944. (American Air Museum in Britain)
Lieutenant Yeager’s official report of the air battle reads (in part):
H. Five Me. 109s destroyed
I. I was leading the Group with Cement Squadron and was roving out to the right of the first box of bombers. I was over STEINHUDER LAKE when 22 Me. 109s crossed in front of my Squadron from 11:00 O’Clock to 1:00 O’Clock. I was coming out of the sun and they were about 1½ miles away at the same level of 25,000 feet. I fell in behind the enemy formation and followed them for about 3 minutes, climbing to 30,000 feet. I still had my wing tanks and had close up to around 1,000 yards, coming within firing range and positioning the Squadron behind the entire enemy formation. Two of the Me. 109s were dodging over to the right. One slowed up and before I could start firing, rolled over and bailed out. The other Me. 109, flying his wing, bailed out immediately after as I was ready to line him in my sights. I was the closest to the tail-end of the enemy formation and no one, but myself was in shooting range and no one was firing. I dropped my tanks and then closed up to the last Jerry and opened fire from 600 yards, using the K-14 sight. I observed strikes all over the ship, particularly heavy in the cockpit. He skidded off to the left. I was closing up on another Me. 109 so I did not follow him down. Lt. STERN, flying in Blue Flight reports this E/A on fire as it passed him and went into a spin. I closed up on the next Me. 109 to 100 yards, skidded to the right and took a deflection shot of about 10°. I gave about a 2 second burst and the whole fuselage split open and blew up after we passed. Another Me. 109 to the right had cut his throttle and was trying to get behind. I broke to the right and quickly rolled to the left on his tail. He started pulling it in and I was pulling 6″G”. I got a lead from around 300 yards and gave him a short burst. There were hits on wings and tail section He snapped to the right 3 times and bailed out when he quit snapping at around 18,000 feet. I did not blackout during this engagement due to the efficiency of the “G” suit. Even though I was skidding I hit the second Me. 109 by keeping the bead and range on the E/A. To my estimation the K-14 sight is the biggest improvement to combat equipment for Fighters up to this date. The Me. 109s appeared to have a type of bubble canopy and had purple noses and were a mousey brown all over. I claim five Me 109s destroyed.
J. Ammunition Expended: 587 rounds .50 cal MG.
Charles E. Yeager, 1st Lt, AC.
Lieutenant Yeager had destroyed five enemy fighters during a single battle. He became “an Ace in one day” and was awarded the Silver Star. Of the twenty-two Me 109s, the 363rd had destroyed eight without losing a single Mustang.
Yeager’s Glamorous Glenn II had previously been assigned to Captain Charles K. Peters and named Daddy Rabbit. Flown by another pilot, Second Lieutenant Horace Roycroft, 44-13897 was destroyed six days later when it crashed in bad weather. Lieutenant Roycroft was killed.
North American Aviation P-51D-5-NA 44-13366 on a test flight near the North American plant at Inglewood, California. This fighter is from the same production block as Yeager’s Glamorous Glenn II.
The P-51D was the predominant version of the North American Aviation World War II fighter. It was a single-seat, single-engine fighter, initially designed for the Royal Air Force. The P-51D was 32 feet, 3.5 inches (9.843 meters) long, with a wingspan of 37 feet (11.278 meters). It was 13 feet, 4.5 inches (4.077 meters) high. The fighter had an empty weight of 7,635 pounds (3,463 kilograms) and a maximum takeoff weight of 12,100 pounds (5,489 kilograms).
Three-view illustration with dimensions. (North American Aviation, Inc.)
The P-51D was powered by a right-hand tractor, liquid-cooled, supercharged, 1,649-cubic-inch-displacement (27.04-liter) Packard V-1650-3 or -7 Merlin single overhead cam (SOHC) 60° V-12 engine with Military Power ratings of 1,380 horsepower at Sea Level, turning 3,000 r.p.m with 60 inches of manifold pressure (V-1650-3), or 1,490 horsepower at Sea Level, turning 3,000 r.p.m. with 61 inches of manifold pressure (V-1650-7). These engines were versions of the Rolls-Royce Merlin 63 and 66, built under license by the Packard Motor Car Company of Detroit, Michigan. The engine drove a four-bladed Hamilton Standard Hydromatic constant-speed propeller with a diameter of 11 feet, 2 inches (3.404 meters) through a 0.479:1 gear reduction.
A Packard Motor Car Company V-1650-7 Merlin V-12 aircraft engine at the Smithsonian Institution National Air and Space Museum. This engine weighs 1,715 pounds (778 kilograms) and produces 1,490 horsepower at 3,000 r.p.m. Packard built 55,873 of the V-1650 series engines. Continental built another 897. The cost per engine ranged from $12,548 to $17,185. (NASM)
The P-51D with a V-1650-7 Merlin had maximum speed at Sea Level of 323 miles per hour (520 kilometers per hour) at the Normal Power setting of 2,700 r.p.m. and 46 inches of manifold pressure, and 375 miles per hour (604 kilometers per hour) at War Emergency Power, 3,000 r.p.m with 67 inches of manifold pressure (5 minute limit). At altitude, using the Military Power setting of 3,000 r.p.m. and 61 inches of manifold pressure (15 minute limit), it had a maximum speed of 439 miles per hour (707 kilometers per hour) at 28,000 feet (8,534 meters). With War Emergency Power the P-51D could reach 442 miles per hour (711 kilometers per hour) at 26,000 feet (7,925 meters).
The P-51D could climb to 20,000 feet (6,096 meters) in 6.4 minutes, and to its service ceiling, 41,600 feet (12,680 meters), in 28 minutes. The airplane’s absolute ceiling was 42,400 feet (12,924 meters).
With 180 gallons (681 liters) internal fuel, the maximum range of the P-51D was 1,108 miles (1,783 kilometers).
Armorers carry Browning AN-M2 .50-caliber machine guns and belts of linked .50-caliber ammunition to a P-51 Mustang. (U.S. Air Force)
The P-51D was armed with six electrically-heated Browning AN-M2 .50-caliber machine guns, with three mounted in each wing. 400 rounds of ammunition were provided for the inner pair of guns, and 270 rounds for each of the other four guns, for a total of 1,880 rounds of ammunition. This was armor piercing, incendiary, and tracer ammunition. The fighter could also carry a 1,000 pound (453.6 kilogram) bomb under each wing in place of drop tanks, or up to ten rockets.
North American Aviation P-51D Mustang. (U.S. Air Force)
A total of 8,156 P-51Ds were produced by North American at Inglewood, California, and Dallas, Texas, and another 200 by the Commonwealth Aircraft Corporation, Melbourne, Australia.
The North American Aviation P-51D Mustang remained in service with the United States Air Force until 27 January 1957, when the last aircraft were retired from the 167th Fighter Squadron, West Virginia National Guard.
North American Aviation P-51D-25-NT Mustang 44-84900 at NACA Langley Memorial Aeronautical Laboratory, circa 1945–1952. (NASA)
Lieutenant Cyrus Bettis and his Curtiss R3C-1 cross the finish line at the 1925 Pulitzer Trophy Race. (NASM)The Pulitzer Trophy
12 October 1925: At Mitchel Field, Long Island, New York, Lieutenant Cyrus Bettis, Air Service, United States Army, set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over 100 kilometers (62.14 miles), flying a Curtiss R3C-1 racing plane, #43. His average speed was 401.28 kilometers per hour (249.34 miles per hour).¹ Lieutenant Bettis was awarded the Pulitzer Trophy.
Bettis also won the Mackay Trophy for 1925.
Cyrus Bettis had previously won the 1924 Mitchell Trophy Race, sponsored by Brigadier General Billy Mitchell in honor of his brother, John L. Mitchell, who was killed during World War I.
Lieutenant Cyrus Bettis, USAAS, with the Curtiss R3C-1 racer at Mitchel Field, Long Island, New York, 12 October 1925. The surface radiators on the wings can be seen. (Curtiss Aeroplane and Motor Co.)Lieutenant Cyrus Bettis, USAAS, with the Curtiss R3C-1 racer at Mitchel Field, Long Island, New York, 12 October 1925. The surface radiators on the wings can be seen. (Curtiss Aeroplane and Motor Co.)
The Curtiss R3C-1 was a single-place, single-engine, single-bay biplane built for especially for air racing. Two were built for the United States Navy and one for the Army. (The Army aircraft is identified by a Navy Bureau of Aeronautics serial number (“Bu. No.”) A-7054. It does not seem to have been assigned an Air Service serial number.) The airplane and its V-1400 engine were built by the Curtiss Aeroplane and Motor Company, which had been founded by Glenn Hammond Curtiss. It was converted to a seaplane configuration with two single-step pontoons, the R3C-2, for the Schneider Trophy Race, two weeks later, 25 October.
The R3C is 19 feet, 8½ inches (6.007 meters) long. The upper wing span is 22 feet (6.706 meters), with a chord of 4 feet, 8¼ inches (1.429 meters). The lower wing span is 20 feet (6.096 meters) with a chord of 3 feet, 3¾ inches (1.010 meters). The R3C-1 had an empty of 2,135 pounds (968 kilograms) and its maximum takeoff weight was 2,738 pounds (1,242 kilograms).
Constructed of wood, the fuselage had four ash longerons and seven birch vertical bulkheads. The framework was covered with two layers of 2-inch (51 millimeter) wide, 3/32-inch (2.38 millimeter) thick spruce strips. These were placed on a 45° diagonal from the fuselage horizontal centerline, with the second layer at 90° to the first. These veneer strips were glued and tacked to the frame. The fuselage was then covered with doped fabric. The wings and tail surfaces were also of wood, with spruce ribs and a covering of spruce strips.
The single-bay wings were wire braced and contained surface radiators made of thin brass sheeting. The radiators contained 12 gallons (45.4 liters) of water, circulating at a rate of 75 gallons (283.9 liters) per minute. By using surface radiators to cool the engine, aerodynamic drag was reduced.
The Curtiss V-1400 engine was developed from the earlier Curtiss D-12. It was a water-cooled, normally aspirated, 1,399.91-cubic-inch-displacement (22.940 liter), dual overhead cam (DOHC) 60° V-12, with a compression ratio of 5.5:1. The V-1400 was rated at 510 horsepower at 2,100 r.p.m., and could produce 619 horsepower at 2,500 r.p.m. It was a direct-drive engine and turned a two-bladed duralumin fixed-pitch propeller with a diameter of 7 feet, 8 inches (2.337 meters). The propeller was designed by Sylvanus Albert Reed, Ph.D. The V-1400 engine weighed 660 pounds (299 kilograms).
The R3C-1 had a fuel capacity of 27 gallons (102 liters). Its range was 290 miles (467 kilometers).
After the Pullitzer race, the R3C-1 was reconfigured as a seaplane for the Schneider Trophy Race. The fixed landing gear was replaced by two single-step pontoons and the airplane was redesignated R3C-2. Additional fuel was carried in the pontoons. On 26 October 1925, 1st Lieutenant James H. Doolittle flew the airplane to win the Coupe d’Aviation Maritime Jacques Schneider at Chesapeake Bay, Maryland.
The R3C-2 is in the collection of the Smithsonian Institution National Air and Space Museum.
Lt. James H. Doolittle (left) and Lt. Cyrus Bettis with the Curtiss R3C-2 (NARA 31758AC)
Cyrus Bettis was born 2 January 1893, at Carsonville, Michigan, the first of three children of John Bettis, a farm worker, and Mattie McCrory Bettis.
Bettis enlisted as a private, first class, in the Aviation Section, Signal Enlisted Reserve Corps, at Detroit, Michigan, 23 January 1918. The Bell Telephone News reported:
Cyrus Bettis has gone to Detroit and enlisted in the Aviation Corps of Uncle Sam’s service.
He expects to be called to service at any time and will probably go East for training. Cyrus has been the efficient and genial manager of the Michigan State Telephone exchange in Fenton for several years. He has made an excellent manager and entrenched himself in the good graces of his patrons and Fenton People in General. —Fenton Independent.
—Bell Telephone News, Volume 7, Number 6, January 1918, at Page 4, Column 1
On 11 September 1918, Cyrus Bettis was commissioned as a second lieutenant, Air Service, United States Army. This commission was vacated 16 September 1920 and he was appointed a second lieutenant, Air Service, with date of rank to 1 July 1920. On 21 March 1921, Bettis was advanced to the rank of first lieutenant, retroactive to 1 July 1920.
On 23 August 1926, flying from Philadelphia to Selfridge Field in Michigan, Bettis flew into terrain in fog in the Allegheny Mountains of western Pennsylvania. With a fractured skull and broken left leg, Bettis crawled several miles to a roadway where he was found, 43 hours after the crash.
Bettis was taken by air ambulance to Walter Reed Army Hospital, but died of spinal meningitis resulting from his injuries, 1 September. He was buried at the Lakeside Cemetery, Port Huron, Michigan.
1st Lieutenant Cyrus Bettis, Air Service, United States Army. (FAI)
12 October 1976: The Sikorsky S-72 Rotor Systems Research Aircraft (RSRA) made its first flight at Stratford, Connecticut. The S-72 was a hybrid aircraft built for the United States Army and the National Aeronautics and Space Administration. Its purpose was to serve as a flight test vehicle for various helicopter rotor configurations.
The S-72 was powered by two General Electric T58-GE-5 turboshaft engines, driving the rotor system, and two General Electric TF34-GE-2 turbofan engines providing thrust for flight in the airplane or compound helicopter configuration.
