Monthly Archives: July 2023

31 July 1971

Apollo 15: Jim Irwin loads the LRV for EVA-1, 31 July 1971. The mountain behind the Lunar Module is Hadley Delta. (David Scott/NASA)

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.


Three-view drawing of Lunar Roving Vehicle with dimensions (Lunar Roving Vehicle Operations Handbook LS006-002-2H, Page 1 – 3, Fig. 1 – 1, The Boeing Company LRV Systems Engineering, Huntsville, AL)

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.

Jim Irwin with LRV at Hadley Rille, 31 July 1971. (Dave Scott/NASA)
Jim Irwin with LRV at Hadley Rille, 30 July 1972. Detail from image above. (Dave Scott/NASA)

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.

Lunar Roving Vehicle wheel and tire assembly. (NASM-A197508300000_PS02)

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]

Apollo 15’s three LRV traverses. Image from the Lunar Reconnaissance Orbiter. (NASA/GSFC/Arizona State University)

© 2018 Bryan R. Swopes

31 July 1944

Commandant Antoine de Saint-Exupéry, Forces Aériennes Françaises Libres. (John Phillips)
Commandant Antoine de Saint-Exupéry, Forces Aériennes Françaises Libres. (John Phillips)

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 was 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.

Antoine de Saint-Exupéry flying his Lockheed F-5B-1-LO Lightning near Alghero on the coast of Sardinia, 1944. (John e Annamaria Phillips Foundation)
Antoine de Saint-Exupéry flying his Lockheed F-5B-1-LO Lightning near Alghero on the coast of Sardinia, 1944. (John e Annamaria Phillips Foundation)

In 1998 a fisherman found his silver identity bracelet on the sea floor south of Marseilles. Parts of the aircraft were recovered in 2003.

Antoine de Saint-Exupéry’s identity bracelet. (WikiTree)

“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.

A pilot boards his Lockheed P-38 Lightning at sunset. (U.S. Air Force)

© 2017, Bryan R. Swopes

31 July 1923: Browning Machine Gun, Caliber .50, AN-M2

This photograph shows SSGT Maynard H. Smith with a Browning .50-caliber machine gun at the left waist position of a B-17 Flying Fortress. (U.S. Air Force)

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.

Three Browning .50-caliber machine guns and belted ammunition installed in the left wing of a Vought-Sikorsky F4U-1 Corsair, 11 August 1942. (Vought-Sikorsky)

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

Illustration of the basic .50-caliber Browning machine gun, AN-M2. (War Department)
John Moses Browning

The Browning Machine Gun (“BMG”) was designed by John Moses Browning, who had 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 AN-M2 aircraft machine gun has an overall length of 56.25 inches (1.429 meters) and weighs 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).

John Browning with a water-cooled version of his .50-caliber machine gun. (Museums at Union Station/The Wall Street Journal)

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.

Armorers load disintegrating-link belts of .50-caliber ammunition for the eight machine guns of a Republic P-47 Thunderbolt. (U.S. Air Force)

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).

A gunner fires the two Browning .50-caliber machine guns of a B-17’s ball turret. (U.S. Air Force)

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).

Lieutenant Clark Gable with a belt of linked .50-caliber machine gun cartridges. The colored tips of the bullets identify armor piercing, incendiary or tracer ammunition.
Armorers carry Browning AN-M2 .50-caliber machine guns and belts of linked ammunition to a P-51 Mustang. (U.S. Air Force)

© 2018, Bryan R. Swopes

31 July 1901

(Bröckelmann (Hrsg): Wir Luftschiffer, Ullstein, 1909)

31 July 1901: At “10 minutes before 11 in the morning,” the gas balloon Preussen (Prussia) began to ascend from Tempelhofer Felde at Berlin, capital city of the Königreich Preußen (Kingdom of Prussia) and the German Empire.

Reinhard Joachim Süring, 1907

Carried aloft in the open gondola were two men, Reinhard Joachim Süring of the Prussian Meteorological Institute, and Josef Arthur Stanislas Berson.

There was a light wind from the northwest, and the air temperature was 23.4 °C. (74.1 °F.). The air pressure was 762.0 millimeters (30.0 inches) of Mercury.

The balloon was made by Continental Caoutchouk und Guttapercha-Compagnie, Hannover, at a cost of 20,000ℳ. To inflate the balloon at the airfield, 1,080 pressurized cylinders containing 5,400 cubic meters (190,700 cubic feet) of hydrogen were used. When fully inflated at altitude, the spherical envelope had a maximum volume of 8,400 cubic meters (296,643 cubic feet).

Josef Arthur Stanislas Berson, 1901

In the gondola were four 1,000 liter (35 cubic foot) cylinders of oxygen for breathing, and 8,000 kilograms (17,637 pounds) pounds of ballast contained in 63 kilogram (139 pound) sand bags and 36 kilogram (79 pound) bags of iron filings.

Süring and Berson reached an altitude of 5,000 meters (16,404 feet) in 40 minutes. The air  temperature was -7 °C. (19.4  °F.). The envelope had reached its maximum volume by this time.

After 3 hours, Preussen had ascended to 8,000 meters (26,247 feet), and in four hours, it reached 9,000 meters (29,528 feet). There, the air temperature was -32 °C. (-25.6 °F.).

The aeronauts had run out of breathing oxygen at 8,170 meters (26,804 feet).

The last observed altitude the men reached was 10,225 meters (33,547 feet), with an air temperature of -35.7 °C. (-32.3 °F.). Josef Berson saw Süring lose consciousness and pulled the emergency valve to vent gas from the balloon and start its descent. He too lost conciousness due to hypoxia.

“. . . dass der Ballon noch kurz nachdem auch der zweite Korbinsasse bei 10500 m das Bewussstein verloren hatte, um mindestens 300 weitere Meter stieg, sonit Maximalhöhe von sicherlich 10800 m (vielleicht 11000 m) erreicht und hierauf unfer Nachwirkung des Ventilzuges in ein jahes Fallen umbog.

[Google English translation: “Shortly after the second basket occupant had lost the awareness stone at 10500 m, the balloon rose at least 300 meters further, reaching a maximum height of certainly 10800 m (perhaps 11000 m), and then reversed our after-effect of the valve train into a sudden fall.]

Both men regained consciousness at about 6,000 meters, but were unable to regain control of the ballon’s descent until 2,500 meters. Süring and Berson returned to Earth near Briesen, Kreis Cottbus, Germany, at 18:25 that evening. The total duration of their flight was 7 hours, 36 minutes.

© 2019, Bryan R. Swopes

30 July 1983

Dago Red, Reno, 1988 (Wikimedia)

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 Course ¹ 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 and assigned 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.

Dago Red would have appeared like this F-51D when in U.S. Air Force markings. This fighter, 44-74998, was the second Mustang to be built by North American Aviation at Inglewood after Dago Red. (U.S. Air Force)

The airplane was issued the civil registration N5410V. The Mustang changed ownership many times before it crashed after an engine failure at Concorde, California, 16 August 1970. After a decade in storage, the wreck was rebuilt as an air racer.

North American Aviation P-51D-30-NA Mustang 44-74996, N5410V. (Unattributed)

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.

Dago Red (Dago Red LLC)
Carrari Dago Red

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 ($13.29 in 2020). (Thanks to “Dr. Vinny” for the info).

³ FAI Record File Number 8437

© 2020, Bryan R. Swopes