At 13:52:31 UTC, 31 July 1971, (T + 120:18:31) the Lunar Roving Vehicle was deployed from Apollo 15’s Lunar Module, Falcon. This was the first time that an LRV had been used on the surface of the moon.
The LRV was a four-wheeled, electrically-powered, surface transportation vehicle designed to carry two astronauts and their equipment to explore areas farther away from the landing site than they would be able to by walking.
The LRV was built by Boeing at Kent, Washington. prime contractor. The wheels, electric motors and suspension system were built by a General Motors subsidiary in Santa Barbara, California.
The lunar rover was constructed of welded aluminum tubing and hinged to allow folding to store aboard the lunar module. It had two folding seats for the astonauts. The four tires were ingeniously constructed of woven steel strands (0.083 cm). about 122 inches (3.10 meters) long. The wheelbase was 90 inches (2.29 meters) and the track was 72 inches (1.83 meters). It was 44.8 inches (1.14 meters) high.
The mass of the empty LRV was 210 kilograms (463 pounds on Earth, but only about 77 pounds on the surface of the Moon), and it was capable of transporting a payload of 490 kilograms (about 81 “moon-pounds”).
The four tires were ingeniously constructed of woven steel strands (0.083 centimeters diameter). The tire was 81.8 centimeters (32.2 inches) in diameter, and 23 centimeters (9.1 inches) wide. The aluminum wheels were 80 centimeters (31.5 inches) in diameter and 24 centimeters (9.4 inches) wide. The tires’ traction was enhanced by “chevrons” made of titanium.
Each wheel was driven by a DC electric motor, capable of 0.25 horsepower at 10,000 r.p.m. There was a 80:1 speed reduction.
Electric power for the vehicle was provided by two 36-volt (+5/-3 volts) silver-zinc potassium hydroxide batteries with a total capacity of 121 amperes/hour. The batteries were not rechargeable.
The Apollo 15 landing crew made three excursions with the LRV, traveling a total distance of 27.8 kilometers (17.3 statute miles) in 3 hours, 26 minutes driving time. The maximum speed reached was 12 km/h (7.5 mph). NASA reported that “the longest single traverse was 12.5 km [7.8 miles] and the maximum range from the LM was 5.0 km. [3.1 miles]“
31 July 1944, famed French aviator and author Antoine de Saint-Exupéry (Antoine Marie Jean-Baptiste Roger, comte de Saint Exupéry), flying for the Forces Aériennes Françaises Libres (the Free French Air Force), departed Borgo Airfield on the island of Corsica. He on a reconnaissance mission of the Rhône Valley. His aircraft was a Lockheed F-5B-1-LO Lightning, serial number 42-68223, an unarmed photo reconnaissance variant of the P-38J Lighting twin-engine fighter.
Saint-Exupéry was never seen again.
In 1998 a fisherman found his silver identity bracelet on the sea floor south of Marseilles. Parts of the aircraft were recovered in 2003.
“Saint-Ex” wrote Night Flight, Flight to Arras, Wind, Sand and Stars and The Little Prince, as well as many other works. He was a gifted writer.
31 July 1923: The original patent application, Serial No. 654,955, for the legendary Browning .50-caliber machine gun was filed with the United States Patent Office on 31 July 1923. Patent Number 1,628,226 was issued to the estate of John Moses Browning by the Patent Office on 10 May 1927.
The majority of United States combat aircraft during World War II were armed with the Browning Machine Gun, Caliber .50, AN-M2. The machine gun could be mounted as a fixed weapon in the aircraft’s wings or nose, in flexible mounts, or power-operated turrets.
“The basic aircraft Browning machine gun, cal. .50, AN-M2. . . is an automatic, recoil-operated, belt-fed, air-cooled machine gun. The metallic link disintegrating belt is used in all firing of the gun. The gun is designed for all cal. .50 aircraft machine gun installations. By properly repositioning some of the component parts, ammunition may be fed into the gun from either the right or the left side.”
—TM9-225 War Department Technical Manual, BROWNING MACHINE GUN, CALIBER .50, AN-M2, AIRCRAFT, BASIC, 28 January 1947, Section II., Paragraph 3. General, at Page 2
The Browning Machine Gun (“BMG”) was designed by John Moses Browning, who also designed the Automatic Pistol, Caliber .45, M1911, the standard sidearm of the U.S. military for 74 years; the Rifle, Caliber .30, Automatic, Browning, M1918 (best known as the “Browning Automatic Rifle” or “BAR”); the Browning Machine Gun, Caliber .30, M1919; and the Browning Hi-Power, a 9 × 19 mm double-action semiautomatic pistol designed for Fabrique National (FN) of Herstal, Belgium.
The basic weapon had an overall length of 56.25 inches (1.429 meters) and weighed 61.00 pounds (27.67 kilograms). The barrel is cylindrical, and 36.00 inches (0.91 meters) long. It is surrounded by a barrel jacket with ventilation holes to dissipate heat. The bore has 8 rifled-grooves with a right-hand twist, making one complete turn in every 15.00 inches (0.381 meters).
The basic AN-M2 gun could be modified to be manually fired with the substitution of a “spade grip” back plate. It could also be changed from left-hand ammunition feed to right hand by reversing some internal parts.
The M2 machine gun had a rate of fire of 750 to 850 rounds per minute.
Ammunition is ball, armor-piercing, armor-piercing-incendiary, tracer, blank (no bullet), and dummy. The armor-piercing cartridge, M2, has a muzzle velocity of 2,840 feet per second (866 meters per second) and maximum range of 7,275 yards (6,652 meters). Some .50-caliber rounds have muzzle velocities as high as 3,450 feet per second (1,052 meters per second), though most range from 2,730 fps to 2,900 fps (832–884 m/s). The ammunition produces chamber pressures of approximately 55,000 pounds per square inch (3,792 bar).
The .50 BMG cartridge is 5.45 inches (13.843 centimeters) long (NATO 12.7 × 99). The rimless, tapered bottleneck case is 3.91 inches (9.931 centimeters) long, with diameters of 0.560 inches (14.224 millimeters) at the neck, 0.735 inches (18.669 millimeters) at the shoulder, and 0.804 inches (20.422 millimeters) at the base. The bullet is 2.31 inches (58.67 millimeters) long, with a maximum diameter of 0.510 inches (12.954 millimeters) and weighs 706.7 grains (1.6 ounces, 45.8 grams).
30 July 1983: Flying a modified World War II-era fighter, Frank Taylor set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a 15/25 Kilometer Straight Course¹ with an average speed of 832.12 kilometers per hour (517.056 miles per hour)—(0.686 Mach). The record flight took place at Mojave Airport (MHV) in the high desert of southern California. The runway elevation at MHV is 2,801 feet above Sea Level (853.8 meters). The airport is about 19 miles (30.6 kilometers) northwest of Edwards Air Force Base.
Flying magazine briefly commented the record run:
“. . . he ran the Mustang’s Merlin engine at 110 inches of manifold pressure[7.93 Bar] and 3,800 r.p.m. (it was designed for 61 inches and 3,000 r.p.m.) and fed it 110 gallons [416.4 liters] of 115/145-octane fuel with manganese additive, enough for only two passes.“
—Flying, Vol. 112, No. 1, January 1985, at Page 64.
Taylor’s air racer was Dago Red,² a North American Aviation P-51D-30-NA Mustang. The fighter had been built at Inglewood, California, in 1944 with U.S. Army Air Corps serial number 44-74996. When the U.S. Air Force retired the last of its Mustangs from Air National Guard service in 1957, 44-74996 was sold as surplus.
It was issued the civil registration N5410V. The Mustang changed ownership many times before it crashed following an engine failure at Concorde, California, 16 August 1970. After a decade in storage, the wreck was rebuilt as an air racer.
The P-51D was modified for air racing. It’s wings were “clipped” (shortened) and the upper fuselage re-shaped, both intended to reduce aerodynamic drag. Approximately 2½ feet (0.76 meters) were removed from each wing tip. The Rolls-Royce Merlin V-12 engine also received many internal modifications to increase power output, and to survive that increase. The Merlin turned a Hamilton Standard “paddle blade” propeller. (Dago Red‘s current engine is based on the post-war Rolls-Royce Merlin 620-series commercial variant.)
On 21 August 1989, an Unlimited Class Grumman F8F-2 Bearcat, Rare Bear, exceeded Dago Red‘s record speed while setting its own FAI record,³ averaging 850.24 kilometers per hour (528.315 miles per hour) over a shorter 3 kilometer course. Both airplanes’ records stood until they were retired due to changes in the sporting code.
In addition to its world speed record, Dago Red has won the National Championship Air Races six times.
¹ FAI Record File Number 8434
² “Dago Red” is a derogatory American slang term referring to an Italian-style blended dark red wine. It was also the name of a commercial brand sold in the 1970s. Dago Red sold for about $2.00 per bottle ($13.00 in 2017). (Thanks to “Dr. Vinny” for the info).
30 July 1939: Major Caleb Vance Haynes, Air Corps, United States Army, with Captain William D. Old, Master Sergeant Adolph Cattarius and Staff Sergeant William J. Heldt, flew the Boeing XB-15 experimental long range heavy bomber to a Fédération Aéronautique Internationale (FAI) World Record for Greatest Payload Carried to a Height of 2,000 meters. The XB-15 carried 14,135 kilograms (31,162 pounds) to an altitude of 2,000 meters (6,562 feet) over Fairfield, Ohio.¹ The flight set a second record by carrying 10,000 kilograms (22,046 pounds) to an altitude of 8,228 feet (2,508 meters).² Both records were certified by the National Aeronautic Association, the American organization representing the FAI.
The Boeing Model 294, designated XB-15 by the Air Corps, was an experimental airplane designed to determine if a bomber with a 5,000 mile range was possible. It was designed at the same time as the Model 299 (XB-17), which had the advantage of lessons learned by the XB-15 design team. The XB-15 was larger and more complex than the XB-17 and took longer to complete. It first flew more than two years after the prototype B-17.
Designers had planned to use an experimental 3,421.194-cubic-inch-displacement (56.063 liter) liquid-cooled, supercharged and turbosupercharged Allison V-3420 twenty-four cylinder, four-bank “double V” engine. It produced a maximum of 2,885 horsepower at 3,000 r.p.m. The engine was not available in time, however, and four air-cooled Pratt & Whitney R-1830 (Twin Wasp) engines were used instead. With one-third the horsepower, this substitution left the experimental bomber hopelessly underpowered as a combat aircraft. (The Douglas XB-19 was retrofitted with V-3420s in 1942, and re-designated XB-19A.)
The XB-15 was a very large four-engine mid-wing monoplane with retractable landing gear. It was of aluminum monocoque construction with fabric-covered flight control surfaces. The XB-15 had a ten-man crew which worked in shifts on long duration flights.
The prototype bomber was 87 feet, 7 inches (26.695 meters) long with a wingspan of 149 feet (45.415 meters) and overall height of 18 feet, 1 inch (5.512 meters). The airplane had an empty weight of 37,709 pounds (17,105 kilograms) and maximum takeoff weight of 70,706 pounds (32,072 kilograms)—later increased to 92,000 pounds (41,730 kilograms).
The XB-15’s wings used a symmetrical airfoil and were very highly tapered (4:1 from root to tip). They had an angle of incidence of 4½° and 4½° dihedral. The total area was 2,780 square feet (258.271 square meters). A contemporary aeronautical publication wrote, “The airfoil provides constant center of pressure, minimum profile drag with flaps up and high maximum lift with flaps down.” The XB-15’s wings were adapted by Boeing for the Model 314 Clipper flying boat.
As built, the XB-15 was equipped with four air-cooled, supercharged, 1,829.39-cubic-inch-displacement (29.978 liter) Pratt & Whitney R-1830-11 (Twin Wasp S1B3-G) two-row 14-cylinder radial engines with a compression ratio of 6.7:1. The R-1830-11 was rated at 850 horsepower at 2,450 r.p.m. and 5,000 feet (1,524 meters), and 1,000 horsepower at 2,600 r.p.m. for take off. They turned three-bladed controllable-pitch propellers through a 3:2 gear reduction. The R-1830-11 was 4 feet, 8.66 inches (1.439 meters) long with a diameter of 4 feet, 0.00 inches (1.219 meters), and weighed 1,320 pounds (599 kilograms).
The experimental airplane had a cruise speed of 152 miles per hour (245 kilometers per hour) at 6,000 feet (1,829 meters), and a maximum speed of 200 miles per hour ( kilometers per hour) at 5,000 feet (1,524 meters). The service ceiling was 18,900 feet (5,761 meters) and maximum range was 5,130 miles (8,256 kilometers).
The bomber could carry a maximum of 12,000 pounds (5,443 kilograms) of bombs in its internal bomb bay, and was armed with three .30-caliber and three .50-caliber machine guns for defense .
Only one XB-15 was built. During World War II it was converted to a transport and re-designated XC-105. In 1945 35-277 was stripped and abandoned at Albrook Field, Territory of the Canal Zone, Panama.