Building World War II Avenger Torpedo Bombers at Mercer Airport

Grumman “Avenger” – Wayne Davis, 1942 [DHS]

As the United States geared up to enter World War II after the attack on Pearl Harbor on December 7, 1941, businesses were ordered to end non-essential production, and therefore began to search for new contracts to contribute to the war effort.

In Hopewell, for example, the H. A. Smith Machine Company (later Rockwell) manufactured over 200,000 aluminum parachute quick releases for the Army Air Corps, plus other products including airplane turn-and-bank indicators.

Navy Avenger torpedo bomber, 1942 [WikiMedia]

In Ewing / West Trenton, the General Motors automotive parts plant was converted into manufacturing the Grumman Avenger torpedo bomber for the Navy. The result was a reworked and enlarged plant, additional buildings, and the construction of what is now the Trenton–Mercer Airport for testing the airplanes.

The rebuilt Trenton plant also needed workers, ramping up to over 12,000 people in 1944. The plant operated full time, around the clock and seven days a week, working ten-hour shifts to meet the production demand.

Current residents remember the impact of these jobs for locals, as, for example, Parker’s Grill Diner at the Pennington Circle was open 24 hours to help serve workers between shifts.

Parker’s Diner, Pennington Circle [HH 2/3/1943]

The Trenton plant also hosted family day activities to support and encourage the workers. Roger Labaw’s grandfather Edgar Labaw worked full-time at the plant during the war in the tool crib. Roger remembers visiting the plant one family weekend when he was around four years old, climbing the long stairway up to the balcony catwalk to watch the production line in action.

“You, Too, Can Build Avengers!” [HH 11/24/1943]

The Navy also provided exhibits of battle-scarred planes that had been returned from action to help encourage patriotic support for the flyers in action using the Trenton airplanes.

And the Trenton plant delivered on its commitments. This required major efforts in the first year to retool the former automotive plant, and the conversion of small-volume manual aircraft construction techniques to large-volume assembly-line automotive manufacturing.

The first Avenger aircraft was delivered on time by the November 1942 deadline, and the plant went on to produce a total of 7,546 Grumman Avengers up to the end of the war in September 1945.

The G. M. Trenton Plant and Mercer County Airfield

G. M. Trenton-Ternstedt Division Plant, opened 1938

The General Motors Trenton-Ternstedt Division plant was built only a few years earlier in 1938 on an 86-acre tract of land “in the heart of rolling farm country” some four miles from the City of Trenton.

The plant manufactured automotive parts, sets of hardware including hinges, door locks, window regulators, roof drip moldings, and trim finish moldings. At its peak, with some 3000 employees, the plant produced 750,000 items a day.

Trenton-Mercer annotated IR Aerial, 1995 [NJGIN]

The plant was located at the southeast corner of the new Mercer County Airfield, which was built on some 500 acres of former farmland acquired by Mercer County at the request of the federal government. The Navy and Civil Aeronautics Authority provided the runways, taxiways, hangars, and other buildings, with the understanding that the county was to receive the airport after the war and continue to operate it.

The airfield, now known as the Trenton–Mercer Airport (TTN), is bounded by I-295 to the north, Bear Tavern Road to the west, Scotch Road and the railroad tracks to the east, and Parkway Avenue to the south.

After each newly-built Avenger was rolled off the production line at the large hanger-sized door on the north side of the plant, it was towed across Parkway Avenue, over a trestle spanning the railroad tracks, and onto the new Mercer County Airfield.

The planes then were taken for a two-hour test flight out over the Atlantic Ocean and back.

G. M. Eastern Aircraft Division

Wildcat fighter and Avenger torpedo bomber

But as the U. S. entered World War II, the G. M. Trenton plant was shut down by government order in December 1941. Then on January 21, 1942, G. M. announced that it had organized a new Eastern Aircraft Division to build fighter planes for the Navy.

The new Division combined five East Coast G. M. automotive plants: the Trenton hardware plant, the Delco-Remy Battery plant in Bloomfield, N. J., Fisher Body plants in Tarrytown, N. Y. and Baltimore, Md., and the automobile assembly plant in Linden, N. J., which could produce 18,832 Oldsmobiles, Buicks, and Pontiacs in a month.

The five Eastern Aircraft plants then were converted to build two different Grumman aircraft, the Avenger torpedo bomber and the Wildcat fighter. Trenton built the Avenger torpedo bomber, and Linden the Wildcat fighter, with various sub-assemblies shipped by train from the other plants. Tarrytown built the two bomber wings, the center section, trailing edges, the motor mount, the cabin, windshield, and upholstery. Baltimore built the bomber’s rear fuselage, the tail assembly, and all control surfaces. And Bloomfield built the electrical tubing and cable assemblies for both planes.

The Aircraft

The Grumman TBF Avenger World War II torpedo bomber and F4F Wildcat fighter were developed initially for the United States Navy. Some three-quarters of the Avenger production was contracted to General Motors (designated TBM). It featured a large bomb bay for a single large torpedo or up to three bombs, and folding wings to maximize space on an aircraft carrier. It had three crew members, the pilot, turret gunner and radioman/bombardier/ventral gunner. It carried three defensive machine guns, facing forward, rear, and downward under the tail.

The Avenger was “the most effective submarine killer and most widely-used torpedo bomber of World War II.” It had overall ruggedness and stability, with good radio facilities, docile handling, and long range. “Pilots say it flew like a truck, for better or worse.” (See Wikipedia)

Avenger being loaded aboard ship

The Avenger, largest single-engine bomber in the country, was a handsome mid-wing monoplane with a barrel chest and belly, topped by a cabin and revolving turret, and with wings that folded back and up like a grasshopper’s. She looked like a big fighter, but within her belly was a bomb bay that concealed a full-size marine torpedo or its equivalent weight in deadly bombs.

The Wildcat was the Navy’s top fighter. It had a speed of better than 300 miles an hour, and an amazing maneuverability, which made it beloved by Navy pilots. Even as these GM men were viewing it for the first time, the Wildcat was well on its way to fame. It had made the Japs pay a terrific price for Wake Island, and “Butch” O’Hare had just flown his way to aerial immortality in a Wildcat the day before by shooting down five Jap bombers singlehanded.

Both planes were equipped with retractable landing gear, with arresting hooks in the rear, and with the same ingenious folding arrangement of the wings. With Pearl Harbor fresh in the memories of all , there was no doubt of the Navy’s urgent need for hundreds of these modern craft as quickly as possible for the war in the Pacific.

George H. W. Bush in Avenger, c 1944 [WikiMedia]

The Avenger gained notoriety as the plane that later President George H. W. Bush was flying in 1944 when he was shot down over the Pacific Ocean by Japanese anti-aircraft fire. Paul Newman also flew the Avenger as a rear gunner.

Clippings posted on Eastern Aircraft plant bulletin boards and in the plant paper played up stories inspiring the workers:

The names of some of [the Navy pilots] were becoming legendary in American history, every week. Flying a Grumman Wildcat over the South Pacific on the twentieth o( February, the 28-year-old Lt. Edward H. O’Hare plunged at nine Japanese bombers roaring toward the American fleet. Five of the bombers fell into the sea; the remainder fled, one of them badly damaged.
On June 1, 1942, the Avenger made its world premiere at the Battle of Midway. Mistaken for a fighter by the Japs who allowed it to come in too close, the Avenger slipped torpedoes from its fat belly, wreaking havoc among the enemy, havoc that may well have caused a turning point in the Pacific War. These and other thrilling events were spread over the American newspapers, and broadcast with almost wild joy from the radio stations.

Retooling

Avenger snaking manufacturing line at Trenton plant

The contracts that General Motors signed in March 1942 specified first deliveries to the Navy by October and November, for the fighter and bomber respectively. Besides the need to build totally new manufacturing lines, this effort also required a major effort to convert from small-volume manual aircraft construction techniques to automotive manufacturing processes for large-volume assembly-line production. At the time, while Grumman was rolling out Wildcats, it had produced only some ten Avengers.

[The] planes were hand-tailored to order by expert, highly skilled craftsmen, comparable to toolmakers, who needed little more than sketches to carry out their work. Because of small orders, tooling, except for the simplest kind, had been out of the question.
The automotive industry, on the other hand, was used to turning out hundreds of thousands and in some cases millions of cars, using some skilled and many semi-skilled and unskilled employees. The sources of component parts were many and varied, but when they arrived at assembly plants they had to go together easily with no hand fitting.

Engine and wings installation at Avenger manufacturing line at Trenton plant

The first step was retooling and rebuilding the plants, ripping out the auto manufacturing lines to install new layouts and machinery. The Trenton plant has a “S”-type final assembly line to snake though all the bays needed to install the hundreds of parts.

Trenton’s removal and structural program began February 27, and extended through mid-July. Millions of pounds of equipment rolled out of the plant, across the highway and into a hastily erected 182,000-square foot storage building. In contrast to Linden, which had practically no machinery that could be adapted to aircraft use, Trenton salvaged 243 out of its total of 1,104 peacetime machines. Of the remainder, 617 were stored; 36 were sold; 106 transferred to other GM Divisions, and 41 returned to original lessors.
Trenton’s moving program was accomplished, as at Linden, with the use of automobile trailer-trucks. More than 120,000 manhours were expended in the stripping of the plant and removing and storing equipment.
One of the many structural changes at Trenton involved breaking through a brick wall at the northwest corner of the building, and installing an 8-ton, 25′ x 70′ door to allow an exit for finished planes to move out of the final assembly bay and across the road to the airport.
… A great deal of ingenuity went into the physical conversion of the plants. … Trenton utilized the framework of its overhead ovens to form a balcony and thus gain badly needed floor space.

Trenton and Linden also required the construction of runways and hangers for testing the aircraft after they were manufactured. The new Trenton airfield was supplied with a huge hangar divided into two sections.

Avenger manufacturing jig at Trenton plant

Staffing

To begin staffing and training for this new effort, A group of supervisors was organized at Trenton to attend the government aircraft training school in Freeport, Long Island, whose instructors were familiar with the Grumman bomber. Other supervisors gained experience by working directly on the production floor at Grumman.

By April, new workers were being hired from vocational
schools where they had been given elementary aircraft training, which was supplemented by in-plant training. Between February and October, 1413 men and 1173 women had graduated from the Trenton training program before being put on productive work at the plant.

Later in 1942, Eastern sent 25 college-educated women to Rutgers University, on General Motors pay, to learn to become junior engineers.

For quality purposes, the Navy required that all welders be Navy-qualified, and to then stamp their identification number on every weld to trace back problems found in the field.

Less than a year previous, there were no more than a handful of Navy-qualified women welders in the whole country. The welding job was considered rather unpleasant, and a “male only” type of job, yet the Eastern Aircraft plants were training as high as 15 to 20% of women for these jobs.

Ramping Up

Production engineering during peacetime in the Trenton plant was less than 40 persons, but by late 1942 there were well over 500 product and process engineers. Purchasing at Trenton rose from 6 to 88.

Working conditions were particularly difficult throughout all of the plants at the start of the program because everything seemed to be going on at one time. The demolition, the structural changes in the plants, the shifting of office space, building cafeterias, enlarging washroom facilities and other physical changes contributed a major part of the confusion.

All this work was to support the deliveries of the Avenger plane one by November 1942.

[In] the huge final assembly bay Trenton’s number one went through the same merciless inspection [as Linden in October] – the same pulling apart and putting together again that the first fighter underwent, until, one day, it was hauled out through the big door, across the street and the Reading Railroad tracks, and over to the hangar. For several days that seemed unending, the new giant was checked and made ready for flight.
On November 11 the sun shone forth, and the big bomber was slipped out of the hangar and into the air on its first but unofficial flight, with Trenton’s chief test pilot at the controls. The next day, amid fanfare, and with great ease, the TBM-1 bomber passed its initial flying test.

By the end of 1942 the Trenton plant had delivered the first three contracted planes, and Linden had delivered 23 planes. Meanwhile, employment throughout the Eastern Aircraft Division had gone up to 22,848 – which was twice the total peak peacetime employment of the five plants.

Avenger bombers from USS Enterprise flying in formation in 1945 [WikiMedia]

Then by the end of 1943, Eastern Aircraft had delivered more Avengers and Wildcats than specified by the Navy contract.

Passengers on the well-traveled B & O Railroad line which passed between the Trenton plant and the airport observed an equally heartening sight, for every day along the hangar apron a new and larger group of torpedo bombers was lined up for delivery. In the sky over both plants the roar of new planes being tested blended into a constant drone.
The 1000th bomber left the final assembly line at Trenton in December, 1943, more than two weeks ahead of schedule and just 13 months after the first plane had been tested.

In 1944, Eastern was the largest producer of Naval aircraft in the country, delivering to both the U.S. Navy and the U. K. Royal Navy.

A History of Eastern Aircraft Division, G. M., 1944

For more on the General Motors Eastern Aircraft Division, see the book, A History of Eastern Aircraft Division, published by the General Motors Corporation in 1944 and distributed to its workers. Unless otherwise noted, quotes and photographs used in this article come from this 160-page book. See SteamPoweredRadio.com on Eastern Aircraft for more information and scans of the book.

The Grumman “Avenger” print was created in 1942 by Wayne Lambert Davis (1904-1988). Davis was the art director for Grumman Aircraft and did several paintings of their planes.

Thanks to Dick Sudlow for making us aware of this story, and sharing the G. M. book and Davis print. He and Roger Labaw also provided personal history on the airport and the plant.

We welcome additional Memorial Day stories and other information, photos, and videos to share (see below).

Building World War II Avenger Torpedo Bombers at Mercer Airport