20 August 1947

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Douglas D-558-I Skystreak Bu. No. 37970 makes a pass over the 3 kilometer course on Muroc Dry Lake. (U.S. Navy)
Douglas D-558-I Skystreak, Bu. No. 37970, makes a pass over the 3-kilometer course at Muroc Dry Lake. (U.S. Navy)

20 August 1947: At Muroc Dry Lake in the high desert of southern California, Commander Turner Foster Caldwell, Jr., United States Navy, flew the first of three Douglas D-558-I Skystreaks, Bu. No. 37970, to a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a 3 Kilometer Straight Course.¹

Four passes were made over the course at an altitude of 200 feet (61 meters) or lower. Two runs were made in each direction to compensate for any head or tail winds. The official speed for a record attempt was the average of the two fastest consecutive passes out of the four.

Commander Caldwell’s average speed was 1,031.178 kilometers per hour (640.744 miles per hour). He was awarded his second Distinguished Flying Cross for this flight.

Commander Turner F. Caldwell, jr., United States Navy with the number one Douglas D-558-I Skystreak, Bu. No. 37970, at Muroc dry Lake, 1947. (U.S. Naval Institute)
Commander Turner F. Caldwell, Jr., United States Navy, with the number one Douglas D-558-I Skystreak, Bu. No. 37970, at Muroc Dry Lake, 1947. (U.S. Naval Institute)

The D-558 Program was intended as a three-phase test program for the U.S. Navy and the National Advisory Committee on Aeronautics (NACA) to investigate transonic and supersonic flight using straight and swept wing aircraft powered by turbojet and/or rocket engines.

The Douglas Aircraft Company designed and built three D-558-I Skystreaks and three D-558-II Skyrockets. The Phase I aircraft were flown by Douglas test pilot Gene May and the Navy’s project officer, Commander Turner Caldwell.

Major Marion E. Carl, USMC, left, and Commander Turner F. Caldwell, Jr., USN, stand with the record-setting Douglas D-558-I Skystreak, Bu. No. 37970, on Muroc Dry Lake. (U.S. Navy)
Major Marion E. Carl, USMC, left, and Commander Turner F. Caldwell, Jr., USN, stand with the record-setting Douglas D-558-I Skystreak, Bu. No. 37970, on Muroc Dry Lake. (U.S. Navy)

The D-558-I Skystreak was a single-engine, turbojet-powered airplane. It was built of magnesium and aluminum for light weight, but was designed to withstand very high acceleration loads. It was 35 feet, 8 inches (10.871 meters) long with a wingspan of 25 feet (7.62 meters) and overall height of 12 feet, 1¾ inches (3.702 meters). The airplane had retractable tricycle landing gear. Its empty weight was approximately 7,500 pounds (3,400 kilograms), landing weight at the conclusion of a flight test was 7,711 pounds (3,498 kilograms). The maximum takeoff weight was 10,105 pounds (4,583.6 kilograms). The aircraft fuel load was 230 gallons (870.7 liters) of kerosene.

This photograph shows two of the three D-558-I Skystreaks being inspected by U.S. navy officials at the Douglas Aircraft Company plant. In the foreground is the number two aircraft, Bu. No. 37971, with the sections o fte hfuselage separted for better viewing. The entire nose section, including teh cockpit, coul dbe jettisoned in an emergency. The second aircraft is Bu. No. 37970, th eSkystrak flown by CDR Caldwell for his speed record. In the background is another Douglas airplane, the famous AD Skyraider. (Douglas Aircraft Company)
This photograph shows two of the three D-558-I Skystreaks being inspected by U.S. Navy officers at the Douglas Aircraft Company plant. In the foreground is the number two aircraft, Bu. No. 37971, with the sections of the fuselage separated. The entire nose section, including the cockpit, could be jettisoned in an emergency. Just beyond that, two wing tip fuel tanks are displayed on a cart. The second aircraft is Bu. No. 37970. An Allison J35-A-11 jet engine is shown between that and the last airplane, another Douglas product, the famous AD Skyraider. (Douglas Aircraft Company)

The D-558-I was powered by a single Allison J35-A-11 turbojet engine. The J35 was a single-spool, axial-flow turbojet with an 11-stage compressor section, 8 combustion chambers and single-stage turbine. The J35-A-11 was rated at 5,000 pounds of thrust (22.24 kilonewtons). The engine was 12 feet, 1.0 inches (3.683 meters) long, 3 feet, 4.0 inches (1.016 meters) in diameter and weighed 2,455 pounds (1,114 kilograms). The J35-A-11 was a production version of the General Electric TG-180, initially produced by Chevrolet as the J35-C-3. It was the first widely-used American jet engine.

The D-558-I had a designed service ceiling of 45,700 feet (13,930 meters). Intended for experimental flights of short duration, it had a very short range and took off and landed from the dry lake at Muroc. (After 1949, this would be known as Edwards Air Force Base.) The experimental airplane was not as fast as the more widely known Bell X-1 rocketplane, but rendered valuable research time in the high transonic range.

Gene May did reach Mach 1.0 in 37970, 29 September 1948, though he was in a 35° dive. This was the highest speed that had been reached up to that time by an airplane capable of taking off and landing under its own power.

The three D-558-I Skystreaks made a total of 229 flights and Bu. No. 37970 made 101 of them. After the Douglas test program was completed, -970 was turned over to NACA as NACA 140, but it was quickly grounded after the crash of the number two aircraft, and was used for spare parts for number three.

Today, 37970 is in the collection of the National Naval Aviation Museum at Naval Air Station Pensacola, Florida. The other surviving Skystreak, Bu. No. 37972, is at the Carolinas Aviation Museum, Charlotte-Douglas International Airport, Charlotte, North Carolina.

Rear Admiral Turner F. Caldwell, Jr., USN, circa 1960. (U.S. Navy)
Rear Admiral Turner F. Caldwell, Jr., United States Navy, circa 1960. (U.S. Navy)
Midshipman Turner F. Caldwell, jr., 1935. (U.S. Navy)

Turner Foster Caldwell, Jr., was born 17 November 1913 at Narbeth, Pennsylvania. He was the first of four children of Lieutenant Turner Foster Caldwell and Eleanor Polk Owings Caldwell. The senior Caldwell was a graduate of Yale University, New Haven, Connecticut, and was commissioned as an ensign, United States Navy, through the Reserve Officers Training Corps (R.O.T.C). Commander Caldwell was assigned to the U.S. Naval Academy, Annapolis, Maryland, 1 September 1930, and was promoted to the rank of captain, 1 October 1930. He retired from the Navy 1 August 1940.

Turner Foster Caldwell, Jr., entered the United States Naval Academy as a midshipman, 12 June 1931. He graduated and was commissioned an Ensign, United States Navy, 6 June 1935.

Ensign Caldwell was promoted to the rank of Lieutenant (Junior Grade), with date of rank 6 June 1938. He was assigned as a flight instructor at NAS Pensacola, Florida. On that same day, Lieutenant (j.g.) Caldwell married Miss Helen Adele Glidden of Coronado, California, at Yuma, Arizona. They would have four children.

By 1940, Lieutenant (j.g.) Caldwell was assigned to Scouting Squadron Five (VS-5). On 7 December 1941, VS-5 was aboard USS Yorktown (CV-5) at Norfolk Virginia.

Caldwell was promoted to Lieutenant, 1 January 1942. He was a Douglas SBD-3 Dauntless scout bomber bomber pilot with Scouting Squadron Five (VS-5) aboard U.S.S. Yorktown (CV-5) and commanded the squadron with its 18 SBD-3s aboard U.S.S. Enterprise (CV-6) during the occupation of Guadalcanal and the Battle of the Eastern Solomons.

Two Douglas SBD-3 Dauntless dive bombers from VB-5, USS Yorktown, 1942. (U.S. Navy)

Between March and September 1942 he was three times awarded the Navy Cross, the U.S. Navy’s second-highest award for valor after the Medal of Honor. He was promoted to lieutenant commander (temporary) 1 May 1943, and to commander, 1 March 1944. (He retained the permanent rank of lieutenant until after the war.)

Later he commanded a night fighter group of F6F Hellcats and TBM Avengers, CVLG(N)-41, assigned to USS Enterprise (CV(N)-6). For his actions during that period he was awarded his first Distinguished Flying Cross and the Legion of Merit.

After the war, Caldwell commanded Carrier Air Group 4 (CVG-4) aboard USS Franklin D. Roosevelt (CVB-42). He was promoted to the rank of captain, 1 July 1954. Captain Caldwell commanded the “long-hull” Essex-class aircraft carrier USS Ticonderoga (CVA-14), from 5 September 1959 to 24 August 1960.

USS Ticonderoga (CVA-14) underway off the Philippines, 24 May 1960. (San Diego Air and Space Museum Archives)

Captain Caldwell was promoted to the rank of rear admiral, 1 April 1963. He rose to the rank of Vice Admiral, 1 November 1967, and served as Director of Anti-Submarine Warfare Plans. Admiral Caldwell retired from the Navy in May 1971. He died at Kilmarnock Hospital, Rappahannock, Virginia, 12 October 1991.

Douglas D-558-I Skystreak, Bu. No. 37970, at the National Naval Aviation Museum, Naval Air Station Pensacola, Florida. (U.S. Navy)
Douglas D-558-I Skystreak, Bu. No. 37970, at the National Naval Aviation Museum, Naval Air Station Pensacola, Florida. (U.S. Navy)

¹ FAI Record File Number 9864

© 2017, Bryan R. Swopes

20 August 1944

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A North American Mustang Mk.I of No. 168 Squadron, Royal Air Force,  banking over Pierrefitte-en-Cinglais in Normandy on a tactical reconnaissance sortie, August 1944. Allied tanks can be seen on the road below. © IWM (C 4559)

20 August 1944: At 16:26 hours, North American Aviation Mustang Mk.I AG346, assigned to No. 168 Squadron,¹ 39 (Reconnaissance) Wing, Second Tactical Air Force, Royal Air Force, took off from an advance airfield, B21, at Sainte-Honorine-des-Pertes, Normandy, France.

AG346 was the very first operational Mustang Mk.I. During this mission, it was hit by intense antiaircraft fire northeast of Gacé. The Mustang’s pilot, Flight Lieutenant Denis Clark, 119758, Royal Air Force Volunteer Reserve, bailed out. He landed safely, but was captured and taken to a German prisoner of war camp at Les Hogues, a small community east of Rouen.

Flight Lieutenant Clark, along with four other prisoners of war,² was shot and killed at the camp on the afternoon 25 August 1944. A Court of Enquiry held in August 1945 found that the five men had been murdered by SS-Obersturmfürer Eugen Gutemann. Gutemann had been captured in Italy on 28 April 1945 and was held as a prisoner of war by the American forces. It is not known if he was ever brought to trial.

Denis Clark was born 17 December 1918 at Stockton-on-Tees, County Durham, England. He was the son of Sydney Clark, an electrician in the chemical industry, and Minnie Gertrude Ritchie.

In 1939, Clark was employed as a civil service clerk. He resided at 3 Crayke Road in Stockton, with his parents and maternal grandmother.

He was married to Miss Beth Ayre of Seaton, County Durham, possibly in July 1942.

Clark entered the United States at Buffalo, New York, on 16 July 1941, having traveled from Toronto, Ontario, Canada. He was trained as a pilot at the Southern Aviation School, a military contract primary flight school in Camden, South Carolina, United States, beginning in July 1941. He was one of 297 RAF pilots to train there between 7 June 1941 and 16 February 1942.

Head stone of Flight Lieuetenant Denis Clark, RAFVR. (Find-a-Grave)

On 7 February 1942 Temporary Flight Sergeant Denis Clark 945260 was promoted to the rank of Pilot Officer on probation (Temporary) 119758.

On 1 October 1942, Pilot Officer (prob.) Denis Clark was promoted to Flying Officer on probation (war substantive).

Flying Officer Clark was later promoted to the rank of Flight Lieutenant. (Date not determined)

Flight Lieutenant Denis Clark, RAFVR, was buried at Les Hogues Communal Cemetery, along with the other four victims. His head stone is engraved

GREATER LOVE HATH NO MAN THAN THIS.
THAT A MAN LAY DOWN HIS LIFE FOR HIS FRIEND.

On 10 September 1945 a warrant was issued as a gratuity for the representatives of deceased officers in the amount of £172/13/7.

North American Aviation Mustang Mk.I AG346 (s/n 73-3099) at Mines Field, California, Summer 1941. Note the short carburetor intake, and compare to the photograph below. (North American Aviation, Inc.)

The very first operational North American Mustang, AG346 (North American Aviation serial number 73-3099) was the second airplane to come off the assembly line at Inglewood, California. North American test pilot Robert Creed Chilton took it for its first flight 3 July 1941. It was the first Mustang Mk.I to be equipped with its full armament.

During flight testing of the first Mk.I, AG345, Chilton and other test pilots heard a banging sound. This was determined to be a resonance in the carburetor intake tract. Also, at high angles of attack, air flow into the intake was decreased. The intake was lengthened. The resonance stopped and air flow to the carburetor was improved.

After flight testing by North American’s test pilots and Royal Air Force fighter pilots Wing Commander Chris Clarkson and Squadron Leader Michael N. (“Red Knight”) Crossley, AG346 was disassembled and crated, then shipped from the port of Long Beach, California, through the Panama Canal and on to England, arriving at Liverpool, 24 October 1941. It was taken to the Lockheed facility at Speke Aerodrome (now, Liverpool John Lennon Airport, LPL) where it was reassembled and put through additional performance and flight tests. Up to 20,000 feet (6,096 meters), AG346 was faster than any other British fighter then in service. A Mk.II reflector gun sight was installed (the same type used in the Supermarine Spitfire), as well as a British VHF radio.

North American Aviation Mustang Mk.I AG346 at Speke Aerodrome, November 1941. Note the lengthened carburetor intake, and compare to the photograph above. © IWM (ATP 10608C)

AG346 was publicly displayed for the British news media at Speke Aerodrome on 5 December 1941.

AG346 was then assigned to an operational RAF fighter squadron. It served with Nos. 225, 63 and 26 Squadrons before being assigned to No. 41 Operations Training Unit. AG346 was returned to operations with No. 16 Squadron, and finally, No. 168 Squadron.

North American Aviation Inc. Mustang Mk.I fighter, AG348, built for the Royal Air Force, at Mines Field, Los Angeles, California, 1941. North American Aviation, Inc., photograph. (Ray Wagner Collection/SDASM)

The Mustang Mk.I was a new fighter built by North American Aviation, Inc., for the Royal Air Force. The British Purchasing Commission asked North American Aviation in Los Angeles, California, to build additional Tomahawks (the RAF variant of the Curtiss-Wright P-40 Warhawk) under license from Curtiss-Wright.

North American countered with a proposal to design a completely new and superior fighter around the P-40’s liquid-cooled Allison V-12 engine, and to begin production in no more time than it would take to get a P-40 production line up and running. The Purchasing Commission agreed, and with a letter of understanding, North American began work on the NA-73X on 1 May 1940. They were to produce 320 fighters before 30 September 1941—approximately 50 per month—at a total price of $14,746,964.35.

Edgar Schmued with P-51-NA 41-37322 (Mustang Mk.IA) (San Diego Air and Space Museum Archives Catalog #: 02-S-00192)

Designed by a team led by Edgar Schmued, the prototype North American Aviation Model NA-73X, serial number 73-3097, registered NX19998, was completed 9 September 1940. After a delay waiting for the Allison V-1710 to arrive, the prototype made its first flight 26 October 1940 with free lance test pilot Vance Breese in the cockpit. This was only 179 days since work began on the project.

In a contract amendment dated 9 December 1940, the British Purchasing Commission directed that the NA-73 would be identified by the name, “Mustang.”

The Mustang Mk.I (NAA Model NA-73) was a single-place, single-engine fighter primarily of metal construction with fabric control surfaces. It was 32 feet, 3 inches (9.830 meters) long with a wingspan of 37 feet, 5/16-inches (11.373 meters) and height of 12 feet, 2½ inches (3.721 meters). The airplane’s empty weight was 6,280 pounds (2,849 kilograms) and loaded weight was 8,400 pounds (3,810 kilograms).

The Mustang Mk.I was powered by a liquid-cooled, supercharged 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710-F3R (V-1710-39) single overhead camshaft (SOHC) 60° V-12 engine with four valves per cylinder and a compression ratio of 6.65:1. The engine had a takeoff rating of 1,150 horsepower at 3,000 r.p.m. at Sea Level with 45.5 inches of manifold pressure (1.51 Bar), and a war emergency rating of 1,490 horsepower with 56 inches of manifold pressure (1.90 Bar). The Allison drove a 10 foot, 9 inch (3.277 meter) diameter, three-bladed, Curtiss Electric constant-speed propeller through a 2.00:1 gear reduction. The V-1710-39 was 7 feet, 4.38 inches (2.245 meters) long, 3 feet, 0.54 inches (0.928 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It weighed 1,310 pounds (594 kilograms).

Allison V-1710-39 (F3R) V-12 aircraft engine.

This engine gave the Mustang Mk.I a maximum speed of 382 miles per hour (615 kilometers per hour) and cruise speed of 300 miles per hour (483 kilometers per hour). The service ceiling was 30,800 feet (9,388 meters) and range was 750 miles (1,207 kilometers).

North American Aviation Mustang Mk.I AG365 of the Air Fighting Development Unit at Duxford, Cambridgeshire, February 1942. © IWM (CH17966)

The Mustang Mk.I was equipped with four Browning AN-M2 .50-caliber machine guns, with one in each wing and two mounted in the nose under the engine and four Browning .303 Mk.II machine guns, two in each wing. The airplane carried 300 rounds of ammunition for each of the .50-caliber guns. Each of the inboard .303s were supplied with 932 rounds; and the outboard .303s, 814 rounds, each.³

The British would recommend that the Allison engine be replaced by the Rolls Royce Merlin V-12. This became the Mustang Mk.III and the U.S.A.A.F. P-51B. Eventually, over 15,000 Mustangs were built, and it was a highly successful combat aircraft.

Today, after 85 years, the Mustang is one of the most recognizable of all airplanes.

Mustang Mk.1 of No. 168 Squadron, Royal Air Force. (RAF)
Mustang Mk.I of No. 168 Squadron, Royal Air Force. (RAF)

¹ No. 168 Squadron was a reconnaissance unit. Its motto was Rerum cognoscere causas (“To know the cause of things”)

² Warrant Officer Griffin James Young R85855, Royal Canadian Air Force, a Spitfire pilot who had been shot down 13 August 1944; Lead Bombardier Jack Martin 976272, 65th Anti-Tank Unit (The Norfolk Yeomanry), Royal Artillery, captured 21 August; an unidentified Gunner, Royal Artillery; and Private Gordon Lafayette Bryant 6969514, 117th Infantry Regiment, 30th Infantry Division, United States Army.

³ Crazy Horse Aviation Photography: https://crazyhorseap.be/mustangs/birth-of-a-legend/A-36.html

© 2025, Bryan R. Swopes

20 August 1940

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The Few. RAF fighter pilots run toward their Hawker Hurricanes. © IWM (HU 49253)

20 August 1940: During World War II, at the height of the Battle of Britain, Prime Minister Winston Churchill spoke to the House of Commons on the state of the war. As he talked about the role of the Royal Air Force in the defense of England, he said,

“Never in the field of human conflict was so much owed by so many to so few.“

(Printed for H.M. Stationery Office by Lowe & Brydon Printers, Ltd.)

To this day, the RAF is known as The Few.

A full transcript of the Prime Minister’s speech can be found at:

https://web.archive.org/web/20161114105625/http://www.winstonchurchill.org:80/resources/speeches/1940-the-finest-hour/113-the-few

Prime Minister Winston Churchill addresses Parliament.

© 2016, Bryan R. Swopes

20 August 1919

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The DELAG airship Bodensee, LZ 120, at Friederichshafen, October 1919. (Library of Congress)

20 August 1919: The first airship built after World War I, Bodensee, LZ 120, made its first flight at Friedrichshafen, Germany, with Captain Bernard Lau in command. LZ 120 was built for Deutsche Luftschiffahrts-Aktiengesellschaft, DELAG, (German Airship Travel Corporation) especially to carry a small complement of passengers. It was hoped that this would generate favorable publicity and help to restart intercity travel by air.

Bodensee was the first fully-streamlined airship. Its teardrop shape was developed by engineer Paul Jaray and had no cylindrical sections. The shape had been tested with scale models in a wind tunnel. LZ 120 was the first airship to have the gondola was attached directly to the bottom of the envelope, decreasing aerodynamic drag.

Scale model of LZ 120 in a wind tunnel at Göttingen, Germany
Scale model of LZ 120 in a wind tunnel at Göttingen, Germany

LZ 120 was a rigid airship, or dirigible, with a metal skeleton structure covered with a cotton fabric envelope. Twelve hydrogen-filled buoyancy tanks were contained within the structure.  A crew of 12 operated the airship and it could carry 20 passengers.

LZ 120 was 396.33 feet (120.8 meters) in length, with a diameter of 61.38 feet (18.71 meters). The airship had a volume of approximately 20,000 cubic meters (706,000 cubic feet). The airship had an empty weight of 13,646 kilograms (36,698 pounds) and a gross weight of 23,239 kilograms (51,233 pounds).

Maybach Mb IVa at the Smithsonian Institution National Air and Space Museum.
Maybach Mb IVa at the Smithsonian Institution National Air and Space Museum.

LZ 120 was powered by four water-cooled, normally-aspirated, 23.093 liter (1,409.2 cubic inches) Maybach Motorenbau GmbH Mb IVa single overhead cam (SOHC) vertical inline six-cylinder engines with a compression ratio of 6.08:1 and four valves per cylinder. The Mb IVa produced 302 horsepower at 1,700 r.p.m., but was derated to 245 horsepower. Two engines were mounted in the aft centerline engine car and drove a two-bladed propeller with a diameter of 5.2 meters (17.1 feet) through a reversible gear train. Each of the other engines were mounted near the center of the airship, outboard. They each turned a two-bladed propeller with a diameter of 3.2 meters (10.5 feet), which were also reversible.

LZ 120 had a maximum speed of 82 miles per hour (132 kilometers per hour).

After two test flights under Captain Lau, Bodensee entered scheduled passenger service on 24 August 1919 under the command of Dr. Hugo Eckener. It flew from Friedrichshafen to the Oberwiesenfeld at Munich, then on to Berlin-Staaken.

In 1921, Bodensee was turned over to Italy as war reparations. It was renamed Esperia and continued in operation until 1928.

© 2016, Bryan R. Swopes