Tag Archives: Pratt & Whitney Wasp S3H1

24 July 1936

Lockheed Electra 10E NR16020 (Lockheed Martin/Purdue University Libraries, Archives and Special Collections)
Lockheed Electra 10E Special NR16020 (Lockheed Martin/Purdue University Libraries, Archives and Special Collections)

24 July 1936: On her 39th birthday, at the Union Air Terminal, Burbank, California, Amelia Earhart accepted delivery of her new Lockheed Electra 10E Special, registered NR16020.

$80,000 to buy the Electra was provided by the Purdue Research Foundation from donations made by several individuals. George Palmer Putnam, Amelia’s husband, made the arrangements to order the airplane and in March 1936 gave Lockheed the authorization to proceed, with delivery requested in June.

Amelia Earhart and her Lockeed Electra.
Amelia Earhart and her Lockeed Electra.

The Electra Model 10 was manufactured by the Lockheed Aircraft Company at Burbank, California. It was an all-metal, twin-engine, low-wing monoplane with retractable landing gear, designed as a small, medium-range airliner. In the standard configuration it carried a crew of 2 and up to 10 passengers. The Model 10 was produced in five variants with a total of 149 airplanes built between August 1934 and July 1941. Lockheed built fifteen Model 10Es. Earhart’s was serial number 1055.

Amelia Earhart in the cocpit of her Lockheed Electra 10E, NR16020.
Amelia Earhart in the cockpit of her Lockheed Electra 10E Special, NR16020. The Sperry GyroPilot is at the center of the instrument panel. (AFP/Getty Images)

Earhart’s Electra was equipped with a Western Electric Model 13C radio transmitter and Model 20B receiver for radio communication. It used a Sperry GyroPilot gyroscopic automatic pilot. Additional modifications included four auxiliary fuel tanks in the passenger compartment, a navigator’s station to the rear of that, elimination of passenger windows, installation of the autopilot, navigation equipment and additional batteries. These modifications varied from the standard airplane enough that it was restricted to carrying only members of required flight crew. This was denoted by the letter “R” in the airplane’s registration.

Amelia Earhart stands behind the additional fuel tanks installed in the aft cabin of her Electra. (AP)
Photographed from the navigator’s station at the rear of the passenger cabin, Amelia Earhart leans over the additional fuel tanks installed in her Electra. (AP)

The Electra was not ready until mid-July. Earhart first flew the new airplane on 21 July with Lockheed test pilot Elmer C. McLeod.

The Electra 10E was 38 feet, 7 inches (11.760 meters) long with a wingspan of 55 feet (16.764 meters) and overall height of 10 feet, 1 inch (3.074 meters). The standard Model 10 had and empty weight of 6,454 pounds (2,927.5 kilograms) and a gross weight of 10,500 pounds (4,762.7 kilograms). NR16020 had an empty weight of 7,265 pounds (3295.4 kilograms). Lockheed’s performance data was calculated using 16,500 pounds (7,484.3 kilograms) as the Maximum Takeoff Weight.

NR16020 had a total fuel capacity of 1,151 gallons (4,357 liters) in ten tanks in the wings and fuselage. 80 gallons (302.8 liters) of lubricating oil for the engines was carried in four tanks.

Amelia Earhart poses with her Electra's Pratt & Whitney Wasp S3H radial engine and two-bladed Hamilton Standard variable-pitch, constant-speed propeller.
Amelia Earhart poses with one of her Electra’s Pratt & Whitney Wasp S3H1 radial engines and two-bladed Hamilton Standard constant-speed propeller. (AP)

Earhart’s Electra 10E Special was powered by two air-cooled, supercharged, 1,343.804-cubic-inch-displacement (22.021 liter) Pratt & Whitney Wasp S3H1 nine-cylinder radial engines, with a compression ratio of 6:1. These engines used a single-stage centrifugal supercharger and were rated at 550 horsepower at 2,200 r.p.m. at 5,000 feet (1,524 meters) and 600 horsepower at 2,250 r.p.m. for take off. The direct-drive engines turned 9 foot, 7/8-inch (3.010 meters) diameter, two-bladed, Hamilton Standard variable-pitch, constant-speed propellers. The Wasp S3H1 is 4 feet, 3.60 inches (1.311 meters) in diameter and 3 feet, 7.01 inches (1.093 meters) long. It weighed 865 pounds (392 kilograms).

The maximum speed for the Model 10E Special at Sea Level and maximum takeoff weight was 177 miles per hour (285 kilometers per hour), a reduction of 25 miles per hour (40 kilometers per hour) over the standard airplane. The maximum range was calculated to be 4,500 miles (7,242 kilometers)

Lockheed test pilot Elmer C. McCleod with a Lockheed Model 10 Electra, "Phantom of the Sky." (Lockheed Martin via dmairfield.com)
Lockheed test pilot Elmer C. McCleod with a Lockheed Model 10 Electra, “Phantom of the Sky.” (Lockheed Martin via dmairfield.com)

© 2017, Bryan R. Swopes

Amelia Earhart’s Lockheed Electra 10E Special, NR16020

Amelia Earhart's Lockheed Electra 10E Special, NR16020, 1937. (Photograph by F.X. O'Grady, Cleveland State University, Michael Schwartz Library, Division of Special Collections)
Amelia Earhart’s Lockheed Electra 10E Special, NR16020, 1937. (Photograph by F.X. O’Grady, Cleveland State University, Michael Schwartz Library, Division of Special Collections)
Amelia Earhart’s Lockheed Model 10E Electra, NR16020. (San Diego Air & Space Museum, Catalog #: 01_00091572)

For her around-the-world flight, the airplane that Amelia Earhart chose was a Lockheed Electra 10E, manufactured by the Lockheed Aircraft Company, Burbank, California. The Electra Model 10 was an all-metal, twin-engine, low-wing monoplane with retractable landing gear, designed as a small, medium-range airliner. In the standard configuration it carried a crew of 2 and up to 10 passengers. The Model 10 was produced in five variants with a total of 149 airplanes built between August 1934 and July 1941. Lockheed built fifteen Model 10Es. Earhart’s was serial number 1055.

Amelia Earhart stands in the cockpit of her unfinished Lockheed Electra 10E Special, serial number 1055, at the Lockheed Aircraft Company factory, Burbank, California, 1936. (Purdue University Libraries, Archives and Special Collections)
Amelia Earhart stands in the cockpit of her unfinished Lockheed Electra 10E Special, serial number 1055, at the Lockheed Aircraft Company, Burbank, California, 1936. (Purdue University Libraries, Archives and Special Collections)

$80,000 to buy the Electra was provided by the Purdue Research Foundation from donations made by several individuals. George Palmer Putnam, Amelia’s husband, made the arrangements to order the airplane and in March 1936 gave Lockheed the authorization to proceed, with delivery requested in June. The modifications included four auxiliary fuel tanks in the passenger compartment, a navigator’s station to the rear of that, elimination of passenger windows, installation of a Sperry autopilot and various radio and navigation equipment and additional batteries. The Electra was not ready until mid-July.

Lockheed Electra 10E NR16020
Lockheed Electra 10E NR16020. (Purdue University Libraries, Archives and Special Collections)

Amelia Earhart test flew the new airplane at Burbank on 21 July with Lockheed test pilot Elmer C. McLeod. She accepted the Electra on her 39th birthday, 24 July 1936. It received civil certification NR16020. (The letter “R” indicates that because of modifications from the standard configuration, the airplane was restricted to carrying only members of the flight crew, although Earhart and her advisor, Paul Mantz, frequently violated this restriction.)

Lockheed technicians check the Electra's fuel capacity with the airplane in normal flight attitude. (Purdue)
Lockheed technicians checking the Electra with the airplane in a normal flight attitude. (Purdue University Libraries, Archives and Special Collections)

The Electra 10E was 38 feet, 7 inches (11.760 meters) long with a wingspan of 55 feet (16.764 meters) and overall height of 10 feet, 1 inch (3.074 meters). The standard Model 10 had an empty weight of 6,454 pounds (2,927.5 kilograms) and a gross weight of 10,500 pounds (4,762.7 kilograms). NR16020 had an empty weight of 7,265 pounds (3295.4 kilograms). Lockheed’s performance data was calculated using 16,500 pounds (7,484.3 kilograms) as the Maximum Takeoff Weight.

Amelia Earhart’s Lockheed Electra 10E Special, NR16020, photographed at Oakland Municipal Airport, 14 March 1937. Note the large navigator’s window in the aft fuselage. This would be replaced by sheet aluminum at Miami.  (William T. Larkins)
Amelia Earhart’s Lockheed Model 10E Electra, NR16020, just prior to departure, Miami, Florida, 1 June 1937. Note that the Electra’s rear window has been replaced by aluminum sheet. (Miami Herald)

NR16020 had a total fuel capacity of 1,151 gallons (4,357 liters) in ten tanks in the wings and fuselage. 80 gallons (302.8 liters) of lubricating oil for the engines was carried in four tanks.

Amelia Earhart poses with her Electra's Pratt and Whitney R-1340-S3H1 Wasp radial engine and two-bladed Hamilton Standard variable-pitch, constant-speed propeller.
Amelia Earhart poses with one of her Electra’s Pratt & Whitney Wasp S3H1 radial engines and its two-bladed Hamilton Standard 12D-40 variable-pitch, constant-speed propeller. (AP)

Earhart’s Electra 10E Special was powered by two air-cooled, supercharged, 1,343.804-cubic-inch-displacement (22.021 liter) Pratt & Whitney Wasp S3H1 nine-cylinder radial engines, with a compression ratio of 6:1. These engines used a single-stage centrifugal supercharger and were rated at 550 horsepower at 2,200 r.p.m. at 5,000 feet (1,524 meters) and 600 horsepower at 2,250 r.p.m. for take off. The direct-drive engines turned 9 foot, 7/8-inch (3.010 meters) diameter, two-bladed, Hamilton Standard variable-pitch, constant-speed propellers. The Wasp S3H1 is 4 feet, 3.60 inches (1.311 meters) in diameter and 3 feet, 7.01 inches (1.093 meters) long. It weighed 865 pounds (392 kilograms).

Ameila Earhart with her Electra 10E, NR16020, at Lockheed Aircraft Company, Burbank, California, December 1936. Earhart’s automobile is a light blue 1936 Cord 810 convertible. (The Autry National Center Museum, Automobile Club of Southern California Archives)
Amelia Earhart with her Electra 10E, NR16020, at Lockheed Aircraft Company, Burbank, California, December 1936. Earhart’s automobile is a light blue 1936 Cord 810 convertible. (The Autry National Center Museum, Automobile Club of Southern California Archives)

A detailed engineering report was prepared by a young Lockheed engineer named Clarence L. (“Kelly”) Johnson to provide data for the best takeoff, climb and cruise performance with the very heavily loaded airplane. The maximum speed for the Model 10E Special at Sea Level and maximum takeoff weight was 177 miles per hour (284.9 kilometers per hour), a reduction of 25 miles per hour (40.2 kilometers per hour) over the standard airplane. The maximum range was calculated to be 4,500 miles (7,242.1 kilometers) using 1,200 gallons (4,542.5 liters) of fuel.

Clarence L. "KellY" Johnson conducted wind tunnel testing of the Model 10 at the University of Michigan.
Clarence L. “Kelly” Johnson conducted wind tunnel testing of the Model 10 at the University of Michigan. (Lockheed Martin)

Johnson would later design many of Lockheed’s most famous aircraft, such as the SR-71A Blackbird Mach 3+ strategic reconnaissance airplane. As a student at the University of Michigan, he worked on the wind tunnel testing of the Lockheed Electra Model 10 and made recommendations that were incorporated into the production airplane.

Amelia Earhart's Lockheed Electra 10E Special NR16020 after it crashed on takeoff from NAS Ford Island, 0553, 20 March 1937.
Amelia Earhart’s Lockheed Electra 10E Special NR16020 after it crashed on takeoff at Luke Field (NAS Ford Island), 0553, 20 March 1937. The preliminary estimate to repair the airplane was $30,000. (Hawaii’s Aviation History)
Amelia Earhart's heavily damaged Lockheed Electra 10E Special, NR16020, after a ground loop on takeoff at Luke Field, Hawaii, 20 March 1937. (Amelia Earhart stands in the cockpit of her unfinished Lockheed Electra 10E Special, serial number 1055, at the Lockheed Aircraft Company factory, Burbank, California, 1936. (Purdue University Libraries, Archives and Special Collections)
Amelia Earhart’s heavily damaged Lockheed Electra 10E Special, NR16020, after a ground loop on takeoff at Luke Field, Hawaii, 20 March 1937. The damaged propellers and engine cowlings have already been removed. The fuselage fuel tanks are being emptied. (Purdue University Libraries, Archives and Special Collections) 

The Electra was heavily damaged when it crashed on takeoff at Luke Field (NAS Ford Island), Honolulu, Hawaii, on the morning of 20 March 1937. It was shipped back to Lockheed for extensive repairs. An investigating board of U.S. Army officers did not report a specific cause for the accident, but there was no evidence of a “blown tire” as had been reported in the newspapers. The repairs were completed by Lockheed and the aircraft certified as airworthy by a Bureau of Commerce inspector, 19 May 1937. The airplane had flown 181 hours, 17 minutes since it was built.

Lockheed engineers use X-ray equipment to scan for hidden damage while the Electra undergoes repairs at Lockheed Aircraft Company, Burbank, California, May 1937.
Lockheed engineers Tom Triplett (left) and Victor Barton use X-ray equipment to scan for hidden damage while the Electra undergoes repairs at Lockheed Aircraft Company, Burbank, California, 3 May 1937. (AP File Photo/Schlesinger Library, Radcliffe College)
Amelia Earhart in teh cockpit of her Lockheed Electra 10E NR16020.(AFP/Getty Images)
Amelia Earhart in the cockpit of her Lockheed Electra 10E NR16020. The Sperry GyroPilot is at the center of the instrument panel. (AFP/Getty Images)
Amelia Earhart stands behind the additional fuel tanks installed in the aft cabin of her Electra. (AP)
Photographed from the rear of the plane, Amelia Earhart leans over the fuel tanks that have been installed in the aft cabin of her Electra. (AP)  

Earhart’s Electra was equipped with a Western Electric Model 13C radio transmitter and Model 20B receiver for radio communication. It used a Sperry GyroPilot gyroscopic automatic pilot.

© 2018, Bryan R. Swopes

22 May 1937

Amelia Earhart's Lockheed Electra 10E, NR16020
Amelia Earhart’s Lockheed Electra 10E Special, NR16020

22 May 1937: Earhart’s Lockheed Electra 10E Special, NR16020 was repaired at Tucson, Arizona after its left engine, a Pratt & Whitney Wasp S3H1 nine-cylinder radial, caught fire while restarting after a fuel stop the previous day. Amelia Earhart and her Navigator, Fred Noonan, and two passengers, flew to New Orleans, Louisiana, on the 22nd.

Although she was actually on the third leg of her second around-the-world-flight attempt, no public announcement had yet been made. She—well, prevaricated—when speaking to local newspaper reporters.

The Arizona Daily Star reported:

Fire Delays Amelia Earhart Here While She Plans Flight

Will Start on World Trip Near the End of This Month She Says While Searching for Fire Extinguisher After Dousing Small Blaze In Plane

     Temporarily grounded in Tucson due to a minor fire which did little damage to the motor of her $90,000 Flying Laboratory, Amelia Earhart announced here last night that with good weather, her second globe girdling trip would start sometime near the end of this month. The route will be the same except for minor changes called for by shifting weather conditions.

     The The Blaze Miss Earhart said was just minor and was caused when an overheated motor “backfired.” It was quickly smothered by a mechanical chemical extinguisher which Miss Earhart released. She said this shot the chemical into all parts of the engine and put the fire out. The damage was negligible she said and she expects to take off today for some eastern city, probably El Paso.

With Husband

     Miss Earhart, with her husband, George Palmer Putnam, New York publisher, Captain Fred Noonan, and her mechanic, Bo McKneely, had just landed at the municipal airport after a flight from Burbank, California, when flames shot from the engine. The aviatrix, who had left the plane, saw the fire break out in the left motor as the plane was being taxied to the hangar. The plane was stopped and she extinguished the blaze with the automatic extinguisher connected with the motor.

     The huge craft, twin-motored Lockhead [sic] Electra, was taken to the hangar, where attendants cleaned the soot and chemical from the engine.

Just Out of Shop

     Miss Earhart and her party came to the Pioneer hotel last night after the plane was taken care of in the municipal hangar. She said the plane had just been out of the factory at Burbank for two days after having been completely overhauled following the crack-up in Honolulu. “It’s just like new now,” and has to be taken on a shake-down flight. I’d like to put 50 hours on it before the big flight.”

     Thursday they flew from Burbank to Oakland and return and yesterday they came here. Putnam is returning to New York and Miss Earhart will fly him part way. “I’m just flying anywhere,” she said, “merely to check the plane and see that everything is working properly. We made all of our fuel tests before and of course don’t have to do that again. Our course this time will be much the same as the last one with the exception of a few changes due to shifting weather. That course was made for conditions as they were in March and now, 60 days later, the weather has altered in some places. The route will be primarily around the world following the equator.”

Something to Do

     Miss Earhart said she would like very much to make this first around the world flight. “If I don’t some one else will,” she added. She said lone flyers have pioneered all the present commercial and it’s up to lone flyers to continue making new courses. “And besides this flight gives me something to do,” she concluded.

     In the meantime Miss Earhart was without a serviceable fire extinguisher. Her trick mechanical one that so neatly put out the fire last night was exhausted and as it must be filled with a special “under pressure” system which the local airport did not possess, she could not have it recharged until she returns to Burbank. She also carries in her plane several of the small quart size hand operated extinguishers. These were also played on yesterday’s blaze by mechanics and were empty.

Extinguishers Needed

     Putnam and Miss Earhart decided that they would have to have some serviceable fire fighting equipment before they left in the morning, just as a precautionary measure. They decided, at least, to get their small hand operated extinguishers recharged. Surely, they thought, they could get them filled in Tucson.

     A half hour on the telephone calling everyone possible from he fire department to the airport revealed no recharge chemical for the extinguishers. They decided to abandon that idea and get an extinguisher, but the little ones they had cost $14. Now $14 is a good bit to pay for additional extinguishers even for a $90,000 plane, when you already have some and all you need is the chemical.

Filler Provided

     Finally the night man at the Motor Service company said he had one dandy big extinguisher of the “turn upside down and let ‘er go” variety which he thought would be just swell for Miss Earhart’s Plane. The phones buzzed again and Putnam said, “Buy it, then we’ll have something.” But this extinguisher, bright and shiny with a pretty red handle, was not filled. That was an easy problem and was soon solved by Chief Joe Robert’s men. He carefully measured each chemical and filled it properly. The copper extinguisher was promptly delivered to Miss Earhart. She started to write out a check to pay for teh apparatus and said, “What date is today?”

     She was told “May 21.”

     “Why that’s right,” she said, “five years ago today I landed in Ireland.”

Made History

     Miss Earhart went on talking about her propsed trip. She might also have mentioned that on that trip five years ago she made world history, being the first woman pilot to fly solo across the Atlantic ocean, her flight was from Newfoundland to Ireland. In January 1935, she flew from Hawaii to California and in May of the same year she flew from Mexico City to New York in a non-stop jump. This past March she set a new record in her flight from California to Honolulu.

     The fire extinguisher man pocketed the check and left. Then half of Tucson called up with extinguishers of all descriptions. Her mechanic secured recharges for the hand extinguishers and all was well. She was told to be sure and keep this newly purchased extinguisher in an upright position. Not expecting to do any loops, she said she would.

The Arizona Daily Star, Tucson, Arizona, Vol. 96, No. 142, Saturday Morning, 22 May 1937, at  Page 1, Columns 6 and 7, and Page 5, Columns 2 and 3

“The next morning at Tucson a dense sandstorm blocked our way, but despite it we took off, leap-frogging at 8,000 feet over El Paso with a seemingly solid mass of sand billowing below us like a turbulent yellow sea. That night we reached New Orleans. . . .”

— Amelia Earhart

Great Circle route between Tucson, Arizona, and New Orleans, Louisiana. 1,069 nautical miles (1,230 statute miles/1,980 kilometers). (Great Circle Mapper)

© 2022, Bryan R. Swopes

20 May 1937

Amelia Earhart with her Lockheed Electra 10E, NR16020.

Leg 1: After her Lockheed Electra 10E Special, NR16020, was repaired by Lockheed following a takeoff accident at Wheeler Field, Oahu, in March, Amelia Earhart repositioned it to Oakland Municipal Airport to begin her second attempt to fly around the world. Because of changing weather patterns since the earlier attempt, this time her route will be eastward.

Great Circle route between Oakland Airport and Union Air Terminal. (Great Circle Mapper)

On 20 May 1937, without any public notice, Earhart and her navigator, Captain Frederick J. Noonan, left Oakland, California, on the first leg of the trip: 283 nautical miles (325 miles (523 kilometers) to Union Air Terminal, Burbank, California (now, Hollywood Burbank Airport—BUR), where the airplane was manufactured and repaired. They arrived at about 6:00 p.m. and remained there over night.

“The rebuilt Electra came out of the Lockheed plant on May 19. Two days later we flew it to Oakland. . .  As that time we had made no announcement of my decision to reverse the direction of the flight. It seemed sensible to slip away as quietly as we could. While I was actually heading for Miami, with hope of keeping on from there eastward, technically the journey from Burbank across the country was a shake-down flight. If difficulties developed we would bring the ship back to the Lockheed plant for further adjustments.”

—Amelia Earhart

Amelia Earhart in the cockpit of her Electra. (Rudy Arnold Collection)

© 2018, Bryan R. Swopes