A Cat of a Different Sort: The Grumman Ag-Cat

Crop dusting expanded considerably after the Second World War with a surplus of pilots, aircraft and engines. Most crop dusting operations used the Boeing/Stearman Kaydet training biplane as it was rugged to deal with the ham fisted flying of students and it was cheap being war surplus as the US military modernized its training fleets in the postwar period. Though plentiful and relatively easy to maintain, a fully loaded Stearman for crop dusting was in most cases underpowered. One of the qualities that made the aircraft so ideal for training was that it required a lot of coordination to minimize its yaw tendencies. It wasn't unusual for a Stearman student to find operational combat aircraft less demanding to fly! That's not to say it was a difficult aircraft in the training environment, but if you were to add a heavy load of chemicals and associated spray equipment, then the Stearman was definitely a handful for crop duster pilots who were flying just a few feet above the ground and then having to climb to avoid treelines and whatever obstacles surrounded most agricultural fields. In 1956, two members of Grumman Aircraft's preliminary design group, Joe Lippert and Arthur Koch, had been touring the Gulf Coast talking to oil industry executives and operators on their requirements for proposed amphibian they were considering. They had a second aircraft in mind as well, a purpose-built crop duster, but the amphibian was their priority at the time of their visit to the Gulf Coast. What Lippert and Koch found was that there was a broad range of needs by the oil industry that they weren't sure a single design could meet all the demands they discussed with prospective customers. Shelving the amphibian project, they then visited farming communities and observed crop dusting operations with considerable interest. Discussions with crop duster pilots revealed some of the problems pilots faced with the near-ubiquitous Stearmans that were the bulk of the crop dusting fleet of the day. While Grumman was not alone in its considerations of a custom-designed crop dusting aircraft, they certainly chose a different design philosophy than other aircraft manufacturers like Piper and Cessna took in their crop dusting designs. 

The Smithsonian's Gruman Ag-Cat
(NASM Udvar-Hazy Center)

Lippert in particular was fascinated with how crop duster operations were getting war surplus radial engines for only $25 to replace the existing worn out Continental R-670 seven-cylinder radial engines for their Stearmans. He astutely realized that the best approach for Grumman was a design that used the 220-hp radial engine as they were inexpensive and plentiful on the aftermarket. This would make acquisitions costs more reasonable and potential owners and operators already had experience operating and maintaining the R-670 engine. Lippert and Koch went back to Leroy Grumman and presented their preliminary specification for what would become the Grumman Ag-Cat. However, Grumman was tied up with a lot of military business in the later half of the 1950s and Grumman told the two men that the new project would have to carried out on a shoestring budget. An empty hangar was secured as a workshop and design space along with tooling that was to be scrapped that they thought might be of use. The entire engineering team for the aircraft consisted of only eight people, two of which were Joe Lippert and Arthur Koch. They borrowed craftsmen from the production floor as needed based on who was available- most of these craftsmen were on the verge of retirement but their skills dating back from the 1920s and 1930s would prove valuable to the Lippert and Koch. While the number of craftsmen working varied based on who was available, it usually averaged about thirty individuals. With the craftsmen working right next to the engineers and draftsmen, a tight-knit group that hearkened back to the Grumman's early days formed. 

Unusually for an aircraft program, the design and build of the Ag-Cat began simultaneously on 30 October 1956. Some of the workers came in on weekends and evenings on their own time to help with the project- after all, the last Grumman biplane was the F3F from the 1930s, so there was considerable interest among the "old hands" at Grumman in the Ag-Cat project (which had yet to get the Ag-Cat name at the time). The fuselage mock up was built in Joe Lippert's garage much to his wife's consternation. Ideas from the mock up then went to the hangar in the morning for incorporation in the aircraft as it came together. To keep things simple, a welded tube fuselage was used with removable aluminum panels to allow the interior to be washed out of any chemical residue from crop dusting. The two wings were staggered with the lower wing 35% aft of the top wing to give the aircraft very benign stall characteristics. This way one wing stalled before the other which insured the pilot would always have some level of control in a stall situation. The four wing panels- left and right top and bottom wings, were all interchangeable which eased maintenance and production costs. The aileron on a top wing panel became a flap if that wing panel were used on the lower wing. The nose sloped downward to improve the pilot's vision during low level flying and the airspeed indicator and engine tachometer were put right at the pilot's eye level to avoid having to look down at the instrument panel. The fuselage structure around the cockpit was designed to absorb a 40G crash- given that 10% of crop duster pilots crashed each year of their careers, making the aircraft survivable in the event of a crash was to be a prime selling point- in fact, from the first delivery in 1959, nine years elapsed before the first Ag-Cat crash. The chemical hopper was installed in the fuselage ahead of the cockpit right at the center of gravity to prevent there being any shifts in the center of gravity as the load was expended. The hopper had a 217 gallon capacity for liquids or 1,200 lbs for dry product. The price was established at $12,995 without the engine and propeller, $13,995 if a power plant package was factory installed. 

N10291, the Grumman Ag-Cat prototype
(Wikipedia/Rene Francillon Collection)

The first flight took place on 27 May 1957, just seven months after design/fabrication of the prototype, N10291, began! Lippert and Koch requested that all the workers who worked on the project bring their wives to the first flight- as many of them had worked additional hours on top of their existing jobs on the project, they thought that the wives should see "the other woman" in their husbands' lives!

With a successful first flight that revealed no major issues, the second prototype joined the test program a month later. Grumman himself invited crop duster pilots from around the country to try out the prototypes and every single one was enthusiastic about the aircraft's handing and tight turning capability given that most crop duster pilots that stalled did so during turns to make another pass. The two prototypes were then taken on a nationwide tour by Lippert and Koch with over 150 pilots trying out the aircraft. One of the crop duster pilots that tried out the aircraft, Dick Reade, suggested the name Ag-Cat to the Grumman team as it was in line with Grumman's naming of its fighter aircraft with feline names (Dick Reade's name is below the cockpit of the Ag-Cat on display at the National Air & Space Museum's Udvar-Hazy Center). While on tour in Texas, Joe Lippert began to take flying lessons and on the day he earned his pilot's license, the first thing he did was try out the Ag-Cat- one of those few occasions where an aircraft's designer got to fly their own aircraft- common in the early days, but increasingly rare as aircraft grew in complexity and performance. 

Leroy Grumman had planned on building the Ag-Cat at the Bethpage facility on Long Island in the event that military sales slowed, but this wasn't to be the case and space was lacking for the production of the Ag-Cat. Grumman had the entire production sub-contracted to Schweizer Aircraft in Elmira, New York, who had the production space and the experience in building welded tube aircraft from their long line of gliders. The first production Ag-Cat was delivered in 1959- Schweizer would build 1,730 Ag-Cats from Grumman until 1980. In 1981, Schweizer purchased the design rights outright from Gulfstream (which was the spin off of Grumman's civilian aircraft business) and would build another 617 Ag-Cats until production ended in 1995. Over its production life, more powerful engines and even turbine power was offered which allowed even greater load carrying capability. In 1995, the Ag-Cat Corporation of Missouri purchased the design rights from Schweizer and a further five Ag-Cats were built before they went bankrupt. A large Ag-Cat operator in Arkansas then bought the design, but I haven't been able to determine who currently holds the design rights to one of the most iconic agricultural aircraft. I did come across an online article from 2011 in the Columbus Telegram in Nebraska about an individual named Jared Storm who owned an agricultural flying service and was in negotiations at the time about relaunching Ag-Cat production at David City Municipal Airport in Nebraska (93Y), but haven't found anything further from that news item. If any of my readers has any information, please do add it in the comments section of this article. 

Further reading: 

The Humble Birth of Grumman Aircraft

C.E. Woolman and the Founding of Delta Airlines

The Birth of the Gulfstream Series of Aircraft

Hatching the Grumman Goose

An Aircraft Manufacturer Goes Into the Boat Business

Sources: Ironworks: The Story of Grumman and Its Aircraft by Terry Treadwell. Tempus Publishing, 2000, pp 160-164. The Smithsonian National Air & Space Museum's entry on the Ag-Cat (http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A20080395000). 

The Humble Birth of Grumman Aircraft

Leroy Grumman (Time Magazine)

In October 1920, the head of the Loening Company, Grover Loening, had been supervising the construction of a two-seat naval floatplane at two locations- at Loening's own plant at 31st Street on the East River in mid-town Manhattan and at the Naval Aircraft Factory in Philadelphia. It was in Philadelphia that Loening convinced one of the Navy's test pilots to resign his commission and join his company. That young 25-year old naval lieutenant was Leroy Grumman. The young Grumman rose quickly to the top ranks of Loening's company and by 1924 Loening had hired two other talented individuals to support Grumman- Jake Swirbul and Bill Schwendler. Loening's company prospered right until the 1927 when Lindbergh's solo flight across the Atlantic sparked the imagination of American business which was already riding a bull market in Wall Street. Though well-run, Loening began to falter and in 1928 Grover Loening sold his company which was to be absorbed by the Keystone Aircraft Company which at the time was building a twin-engine bomber for the US Army Air Corps. In less than a year, Keystone itself was purchased by Curtiss Wright. Under the terms of the sale, Loening's Manhattan factory would be shut down and all the employees were assured employment if they moved to Keystone's main facility in Bristol, Pennsylvania.

Leroy Grumman and his two closest friends, Jake Swirbul and Bill Schwendler, weren't happy about having to move to Pennsylvania as they had settled in the New York City area and had families that would have to be moved. So in 1929 the trio decided they'd form their own aircraft company and stay in the New York City area. Since Grover Loening and his brother were barred from forming another aircraft company as part of the terms of the sale, they decided that investing in Grumman's fledgling enterprise would be the next best thing. Their first act was to hire Loening's treasurer who also happened to be from a prosperous New York family that offered to invest with Grumman as well. In contrast to the businesses of the day, however, Grumman decided that control of the company would rest only with a few individuals and to not canvas Wall Street for further investors. It proved to be a wise move with the Wall Street crash just over a month away. 

Grumman then set about to recruit the thirty most skilled employees at the Loening plant. His years of service under Loening endeared him to many of the Loening workers and all asked, with the exception of one or two, threw their fate into Grumman's hands. In addition, Grumman, being a financially cautious individual, decided that his new company would only seek the business of the US military, preferably the US Navy given Grumman's background as a naval aviator and their long history of doing business with the sea service during their employment with Loening. In order to fund their day-to-day operations, they would repair existing Loening amphibians at a rented facility in Long Island. 

On 5 December 1929, Leroy Grumman and his five founding associates met for the first time and the following day the Grumman Aircraft Engineering Company was born. Much of the company's initial capital came from Grumman's severance pay from Loening. Jake Swirbul's widowed mother worked for a wealthy Long Island family that so much of her that they lent Swirbul enough money to become the first vice-president of Grumman. A few months later in March 1930, the rest of the tiny company's employees were allowed to purchase stock (On the eve of the maiden flight of the Grumman F-14 Tomcat, those employees' initial investment over 40 years had multiplied by a factor of 7,700!). 

Their first design proposal was for the US Navy, which at the time had a two-seat scout biplane, the Vought O2U Corsair. The Corsair could be fitted with floats for operation from cruisers and battleships or it could be fitted with landing gear for operation from aircraft carriers. Grumman's proposal was for a new float that was not only lighter and stronger than the existing main float used on the Corsair, but it would also incorporate a fully-retractable landing gear to allow true amphibious capability. In 1930, fully-retractable landing gear were a novelty- on the Loening amphibians, the landing gear simply swung upward out of the way but what Grumman and his team proposed was a streamlined arrangement in which the gear would be fully retracted into the sides of the central float. 

Vought O2U with the Grumman-design center float (Wikipedia)

The Navy was intrigued by this modification of its O2U scoutplanes, and asked Grumman for a demonstration. Many in the Navy were skeptical that a float lighter than the existing float could be stronger, let alone be strong enough to accommodate a full-retractable landing gear. But Grumman's design was an early pioneer in monocoque construction in which the skin of the float carried a good portion of the stress loads and as such, didn't need a heavy internal framework that was the standard in aircraft construction of the day. The Navy paid Grumman $33,700 for two such prototype floats for testing at the naval yards in Anacostia in Washington, DC. The floats would be attached to Vought O2Us that would be launched from test catapults as that was the most stress anticipated on such a float arrangement. The landing gear was manually operated, but was designed so that either mechanical or hydraulic power could be added.

On the day of the flight tests, the Navy couldn't find an observer willing to sit in the second seat of the modified scoutplane. Many thought Grumman's float would either crumple up on launch or collapse on landing either on land or on water. Not wanting to delay the flight tests, both Leroy Grumman and Jake Swirbul both volunteered to sit in the observer's seat on different flights to prove their faith in the monocoque design. The day's test flights were of course successful and Grumman walked away with his first Navy contract for what was called the Grumman Model A float. In addition, the Navy had asked Grumman the possibility of using the retractable landing gear on its single seat carrier fighters. Grumman offered to go one better and on February 1930 began work on what would be come the first Grumman fighter, the FF-1. Grumman's landing gear design would go on to be used on not just the FF-1, but also the F2F and F3F biplane carrier fighters and on the F4F Wildcat used in the Second World War. 

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p17-41.

C.E. Woolman and the Founding of Delta Air Lines

C.E. Woolman (Minnesota Public Radio)

Collett Everman Woolman was born in Indiana in 1889 and was raised in the academic environment of Champaign-Urbana, Illinois, where his father taught physics at the University of Illinois. Woolman's interest in aviation began at an early age when he and his friends appropriated every clothesline in his neighborhood to build a giant passenger-carrying kite which fortunately for history, crashed before anyone tried to take flight in it. As a freshman, he even built a crude airplane which had to make a forced landing on his university campus. In his sophomore year of collge at the University of Illinois, he learned of the first aviation world meet to be held in Reims, France, and the ambitious Woolman managed to get a job tending a herd of 800 travelling calves to get to France. On his return, he helped pioneer aviator Claude Grahame-White overhaul a rotary engine in the passenger steamer's cargo hold in preparation for an airshow in Boston. 

He graduated in 1912 from the University of Illinois with a bachelor's degree in agriculture. That's right, farming. The legendary founder and head of Delta Airlines studied agriculture in college, hardly the field to propel him into aviation, but in those days, aviation as a business and industry hardly existed and was more the realm of half-cocked mad scientist types to be shunned by the general population. In fact, if you wanted to look up Glenn Martin's aircraft company in Los Angeles in those days in the phone book, it was listed under "Amusements"! With a fresh degree in agriculture, Woolman moved south to farm various locales in Mississippi before becoming the manager of a 7000 acre plantation in northern Louisiana. 

In 1913 he joined the extension department of Louisiana State University at Baton Rouge as an agricultural sciences instructor who travelled out to farmers to pass on the latest techniques. In 1914 the US Congress passed the Smith-Lever Act which formalized the extension cooperative system in which universities would reach out to farmers to formally educate them on the latest developments in agriculture. With this new law, the young C.E. Woolman became LSU's first extension agent in Lousiana and based his operation in Monroe, Louisiana. 

Travelling throughout Louisiana, he not only met with farmers and plantation owners but also consulted with financial institutions on investing in agriculture as well as liasing with the agricultural scientists back at the LSU campus. It was during this time that the boll weevil infestation was ravaging the US cotton crop. A chemical had been developed which was effective against the boll weevil; calcium arsenate was a dry powder which worked well, but was cumbersome and inefficient when applied from the ground. 

The federal government had experimented with US Army planes in rudimentary crop dusting efforts, but a grant was given to an entomologist by the name of Dr. Bert Coad at the US Department of Agriculture's Delta Laboratory in Tallulah, Louisiana. Coad had difficulty finding an airplane that possessed a good load carrying capacity to carry enough calcium arsenate powder to dust an entire cotton field. Coad hooked up with a small company called Huff-Daland which was trying to market a military training biplane. Struggling for cash, Huff-Daland eagerly cooperated with Bert Coad in his crop dusting trials.

Huff-Daland Duster at the National Air & Space Museum
(Smithsonian Air & Space Museum)

Given Woolman's job with LSU's agricultural extension, he observed many of Coad's trials with interest. Encouraged by Woolman's favorable assessments of the effectiveness of aerial crop dusting against the boll weevil, Coad tried to get more federal grant money to expand the enterprise. Woolman had enthusiastically spread the word to area farmers that there was a new weapon against the boll weevil and soon Coad found he didn't have the resources to meet the demand. But the US Department of Agriculture saw Coad's trials as only an experiment and failed to provide more resources. 

In 1923, the vice president of Huff-Daland happend to stop by Tallulah, Louisiana, on his way to Texas to demonstrate a Huff-Daland trainer to the US Army. There he ran into Coad and Woolman at the airport and found their work intriguing and thought it would make for a great commercial opportunity with the right amount of investment. He convinced Huff-Daland to set up a crop dusting division in northern Louisiana and he put Coad in charge. But Coad wasn't the best of salesmen and he asked Huff-Daland to hire C.E. Woolman as it's head of sales. Huff-Daland Dusters was originally based in Macon, Georgia, with the bulk of their original business being the spraying of peach orchards. However, by 1925 the company moved to Monroe, Louisiana, with the promise of local investment that Woodman had secured. Coad's former laboratory in Tallulah was close by and Woolman's work with the farmers there brought them a ready-made clientele. Woolman, in that classic Southern genteel style he would become famous for, convinced local business leaders in Monroe to invest in Huff-Daland Dusting Company and by the mid 1920s, Woolman had expanded the dusting operation to include Texas, Arakansas, California, North Carolina and even a contract to do crop dusting for the Peruvian government. In a few short years, Huff Daland Dusters would have one of the largest private fleets of aircraft in the United States, even more than some of the airlines of the day.

Delta's first logo (Delta Flight Museum)

Within a few years, Woolman himself would buy the entire dusting operation from Huff-Daland while Huff-Daland Aircraft itself moved to Pennsylvania and was renamed Keystone Aircraft, one of the pioneering aircraft companies of the day. Woodman wanted a simple name preferably with five letters and it was his long time administrative assistant Catherine Fitzgerald, who suggested the name "Delta". Given its long time service area of the Mississippi Delta region, the name was perfect and the triangle was not too dissimilar to the Huff-Daland Dusting Company logo. One of Delta's first non-dusting contract came from the Army Corps of Engineers who wanted aerial surveys done of the levees along the Mississippi River after some disastrous floods in 1927. Woodman likely was considering starting an airline around that time, a federal airmail survey passed through Monroe and he had been looking at a proposed air mail route that connected Shreveport, Monroe, Jackson, Meridian, Tuscaloosa, and Birmingham. In 1929, he even went as far as got advice from a Minneapolis-based airline (Northwest) who offered him suggestions on operating a passenger-carrying airline. However, Delta's finances at the time weren't in a position to get the Ford or Fokker trimotor airliners used by the major airlines of the day. As luck would have it, in a small town not far from Monroe was a businessman named John Fox who had just started a local air service that concentrated on taking people up for joyrides in Travel Air biplanes. Fox had ordered a larger aircraft, a high-wing monoplane with a six-seat enclosed cabin Travel Air S6000. Fox and Woodman met in 1929 and hit it off well given their mutual aspirations of starting an airline. Delta purchased the assets of Fox Flying Service in exchange for Delta stock which made John Fox the biggest Delta shareholder. Fox was named an officer of the company by Woodman and moved to Monroe to help Woodman get their airline off the ground.  Delta Air Service carried its first passenger from Dallas, Texas, to Monroe, Louisiana in on 17 June 1929. Though Delta's agricultural operations would dominate for a while longer, it was a humble beginning for a Southern farmer and his airline.........

Historical Tangent: Thomas Huff and Elliot Daland started their company in 1920 as Ogdensburg Aeroway Company in 1920 in Ogdensburg, New York. They soon became the Huff Daland Aero Company and in 1924 their chief designer was James S. McDonnell (yes, *that* McDonnell that would go on to establish McDonnell Aircraft in St. Louis during the Second  World War). Thomas Huff sold his share of the company in 1926 and it was acquired by a securities firm who invested a significant amount in Huff Daland and moved the operation from New York to Bristol, Pennsylvania and renamed it Keystone Aircraft. Keystone merged with Loening Aircraft in 1928 and the following year Keystone-Loening was taken over by Curtiss Wright. The Loening plant on the East River in New York City was closed by Curtiss and operations transferred to Bristol. A handful of Loening workers and management, though, all New Yorkers, elected to stay and form their own company to stay in New York. The leader of the group was none other than Leroy Grumman. Yes, *that* Grumman!

Sources: Delta: The History of an Airline by W. David Lewis and Wesley Phillips Newton. University of Georgia Press, 1979, pp 1-24. Delta: An Airline and Its Aircraft by R.E.G. Davies. Palawdr Press, 1990, pp 8-13. 

The Birth of the Gulfstream Series of Aircraft

Before the Second World War, Grumman Aircraft had a partnership with New York-based Gillies Aviation to market and sell the company's line of amphibian aircraft. One Gillies' salesmen, a pilot named Henry Schiebel, eventually came to work for Grumman during the war as a company test pilot. In the postwar period as Grumman began to diversify its offerings outside of naval aircraft, Schiebel was the head of the company's transportation department, flying the company's executives on various business trips. At the time, Grumman's civilian offerings were limited to its amphibian line of aircraft from the Widgeon and Goose on the small end of the scale to the Albatross and Mallard on the top end. Because of Schiebel's sales background, he often found himself in the role of pitching one of the amphibians to a civilian customer as the need arose.

Though Schiebel wasn't an engineer, he began working with a small group of engineers that since the mid-1950s in their free time after hours had been putting some effort into coming up with a civilian feederliner that could also be used for corporate and private use. Unlike Grumman's previous offerings, what the engineers had in mind was a land-based aircraft that would offer a level of comfort and performance that justified their forecast one-million dollar price given that most companies in those days could get a good used DC-3 for just over $200,000. Schiebel's job was to bring to the after-hours effort not just a pilot's perspective, but also the perspective of someone who was intimately aware of the needs of civilian owners and operators. 

Their starting point was actually basing their aircraft's cabin cross-section on that of the DC-3. Grumman had several of them in its corporate flight department and everyone agreed that they were the most comfortable aircraft when it came to business travel compared to other types of aircraft available on the market. Their second consideration was the type of powerplant to use- again, all were in agreement that a turboprop would offered good operating economics as well as fuel efficiency that translated into a good operating range. At the time, the Rolls-Royce Dart engine had the most flying time of any turboprop and was well-known in the commercial world as it already powered several successful airliners like the Vickers Viscount. The team was well aware that their biggest competition would be pure jets and the prototype Lockheed Jetstar was already flying. This was long before turbofans entered the picture and the choice of a turboprop, while slower in speed than a pure jet, offered better range. 

By the point that the project had matured to the point that it was time to pitch it to Leroy Grumman, a minor bit of discord developed within the team about whether this new aircraft should have a low-wing or a high-wing. Aerodynamically there were no disadvantages or advantages to either layout. Schiebel, drawing upon his experiences in aircraft sales, pushed for a low-wing layout. Rather amusingly, the debate would be settled by Leroy Grumman himself when he was presented with the project by Schiebel and the adhoc group of engineers. Two models of the design were made- one with a low-mounted wing and one with a high-mounted wing. Both were shown to Grumman and he immediately settled on the low-winged configuration. He then summoned the heads of finance and his lieutenants to view the engineers presentation. Building the aircraft would require an initial investment of $23 million and Grumman himself is reportedly to have said "I'd like to build this airplane before I retire." Some had asked whether a market survey should be done first before committing to the project, but Grumman felt comfortable with the fact that Henry Schiebel had been involved with the project all along and trusted his thoughts on the market for the aircraft. Interestingly a competitor did do a market survey and predicted that Grumman would sell less than 20 of the aircraft.

 

It turned out that after the maiden flight of the Grumman Gulfstream I on 14 August 1958, the company would go on and build approximately 200 Gulfstream Is and launched in iconic line of business aircraft that have become near-synonymous with business aircraft. The Gulfstream I had two features which have been kept in every successive Gulfstream right up to the current Gulfstream 650 that's in flight testing- the characteristic nose/cockpit shape and the large oval windows, the largest of any business aircraft. 

The first Gulfstream Is sold for $845,000 and the first one went to the Sinclair Refining Company and the FAA, responsible for certifying the aircraft, even got two for its own use. By 1963, Grumman was building two Gulfstream Is a month and began work on transitioning the product line to jet power with the Rolls-Royce Spey-powered Gulfstream II which first flew in October 1966. The new Gulfstream jets were built a new plant set up in Savannah, Georgia, by Grumman and though Grumman is no longer involved with the production of Gulfstream jets, the plant in Savannah is still to this day where they are built. 

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p275-279.

Two Paperclips and an Eraser Contribute to Victory in WW2

The first variants of the Navy's premier carrier-borne fighter of the first half of the Second World War, the Grumman F4F Wildcat, were hampered by one weakness even before they took off from their aircraft carriers- lacking a folding wing, the first versions of the Wildcat took up quite a bit of space on the carrier and, by extension, that limited the number of Wildcats that could carried aboard. Given combat losses that would inevitably occur, having as many aircraft on the carrier as possible conferred tactical advantages in battle. The current production version of the Wildcat at the time was the F4F-3. 

The most obvious answer would be hinge the wings' outer sections and folding them upward as was done on most carrier aircraft (even to this day). However, to Leroy Grumman and his engineering team, that wasn't an optimal answer as that increased the height of the stowed aircraft- if the wing could be folded in a way that didn't increase the height of the aircraft, then extra aircraft could be winched up and stowed up near the ceiling of the hangar deck. Grumman reasoned that the optimum geometry would be to somehow fold the wing back not unlike the way a bird folded its wings back along its body. Grumman drew upon his engineering intuition and reasoned that the wing had to rotate about a pivot point. He took a draftsman's eraser and two paperclips; he bent one end of the paperclips and began to stick them into the eraser. The eraser was the body of the Wildcat and the paperclips were the wings. By trying different angles, Grumman managed to figure out the angle needed to that when the clip was rotated, it folded back flat against the eraser. This was known in engineering parlance as a skewed axis. 

In the Wildcat, this axis was a pivot set into the wing root that pointed outward and backward at angle into the moving portion of the wing. As the wing rotated about this pivot, it folded back against fuselage, making the F4F a compact package- so compact, that six F4Fs with what Grumman called the "Sto-Wing" could fit into a deck or hangar space normally occupied by two F4Fs that had nonfolding wings. At first it was planned to use hydraulics to fold the wings, but it was found this added excessive weight, so the wings would have to be folded manually by the deck crew. A large master pin would lock the wing in position either extended or folded.

The Sto-Wing was immediately placed into the production line- with the current Wildcat model being the F4F-3, those with the Sto-Wing became the F4F-4. From a tactical standpoint, an aircraft carrier could now carry twice as many F4Fs as before with the wingspan of the Wildcat going from 39 feet to just over 14 feet folded. Deck handling improved as it was easier to move an F4F with the wings folded on a crowded flight deck or in a packed hangar deck. The Sto-Wing concept was applied as well to the TBF Avenger and the F4F Wildcat's successor, the F6F Hellcat. And it's seen today on carrier decks with the Northrop Grumman E-2 Hawkeye- since the E-2 had the dish-like radome above the fusleage, the wings couldn't be folded up and over each other as was done on other long-span carrier aircraft like the Lockheed S-2 Viking. So E-2 Hawkeye's wings use the Grumman Sto-Wing principle to fold back towards the tail.

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p124-125.

The Groundbreaking Gun Turret of the TBF Avenger

On 8 April 1940 the US Navy ordered two prototypes from Grumman for a multirole torpedo bomber to replace the antiquated Douglas TBD Devastator. With Grumman having well-established credentials in designing tough carrier-based fighters, what would be come the TBF Avenger had a remarkably smooth development period due to the experience built up in designing and producing the same company's F4F Wildcat fighter. Their biggest single-engine carrier-based aircraft to date, a fully-loaded Avenger was twice as heavy as two Wildcats. But one of the Avenger's most significant technical innovations also happens to be one of the least-known features of the aircraft. 

At the time the Avenger was ordered by the US Navy, few aircraft in any nation's service worldwide used gun turrets as most defensive guns were trained manually on gimbaled mounts through open hatches and windows. The gun turrets that were in existence used either mechanical or hydraulic systems to rotate the turret in azimuth and to raise or lower the gun in elevation. Mechanical systems used wheels and brakes operated by the gunner and hydraulic turrets used the same systems as mechanical systems but with the addition of hydraulic power to lessen the physical effort needed by the gunner to track and engage targets. Neither system was satisfactory for Grumman's engineers and combat use showed that the systems were either too slow or too heavy for use on a single-engined carrier-based torpedo bomber. The Navy asked Grumman for a more responsive system that was also lightweight. 

Leroy Grumman turned over the challenge to the first electrical engineer hired by the company, a young ex-General Electric engineer named Oscar Olsen. Grumman assigned him the challenge of developing an electrically-driven system for the Avenger's gun turret. The challenge was bigger than it seemed- depending upon the flight attitude of the aircraft, different sides of the circumference of the turret would present different loads to any drive system resulting in differing speeds which would adversely affect target tracking. For instance, if the Avenger were in a dive, and the turret was rotating to engage an enemy aircraft, one side of the turret is rotating downward and has less of a load on the motor than the opposite side that is rotating upward against gravity and thereby presenting more of a load on the motor. 

Olsen fell back on his experience with GE and looked at what were called amplidyne motors. These were electrical motors in which both the speed and torque of the motor can be controlled. Olsen knew that GE had made them for the construction industry where two motors were used to lift up a bridge span. Being on opposite ends of the span, it was important to have absolute control over both the speed and torque of the motors winching up the span. GE also made amplidyne motors for the steel industry to wind up the steel sheet used to make tin cans. As the flattened sheet comes out of the furnace, the tension has to kept within a narrow range or the sheet sags, or worse, breaks. Amplidyne motors were used to spool up the steel sheet- as the roll got bigger and heavier, the torque could be increased but the speed controlled to maintain the same amount of tension on the steel sheet. Olsen figured out that a set of amplidyne motors synchronized with an electric circuit would allow the Avenger's gunner to smoothly and quickly move the turret with just fingertip controls. 

Olsen paid a visit to his old engineering colleagues at GE's research facility and explained what he needed and why he needed it. In a short period of time, GE produced by hand several prototypes of a small but powerful amplidyne motor that were installed and successfully tested on the TBF Avenger prototypes, proving the electrically-powered amplidyne motor-driven turret to be superior in all respects to both mechanical and hydraulically-driven gun turrets. The gun turrets on many different combat aircraft subsequently were patterned on the amplidyne motor-driven system devised by Oscar Olseon and pioneered in operational use by the TBF Avenger. 

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p116-124.

Hatching the Grumman Goose

In the fall of 1936 Grumman Aircraft was rapidly expanding having proven itself capable of producing fast advanced Navy biplane fighters that were set the standard for toughness during carrier operations. The company had just broken ground on its Bethpage plant on Long Island that would be its long-time home right on up to the production of the F-14 Tomcat. With the business of the United States Navy secure, Leroy Grumman and the founders of the company decided it was time to diversify by entering the civil market with their first aircraft designed for the commercial market, the Grumman G-21 Goose, which also would be Grumman's first monoplane design as well as it's first twin-engine aircraft. The Goose drew upon the company's experience with amphibians (all the founders of the company as well as Leroy Grumman had worked previously with Loening Aircraft on that company's amphibian designs) as well as its work on the lightweight floats added to the Navy's O2U Corsair biplanes and the Navy's JF Duck utility seaplane. 

While Grumman's team was beginning early design work on what would become the Goose, a group of ten wealthy Long Island businessmen and avid sportsmen led by New York businessman Wilton Lloyd-Smith, formed a syndicate to look at the possibility of having a private aircraft built to their specifications. Since the members of Lloyd-Smith's group all lived on waterfront estates on Long Island, their aircraft would have to be a seaplane that would allow them to commute back and forth between the Wall Street waterfront and their Long Island estates. Since some of the members didn't have waterfront property, the aircraft would have to be amphibious as well. With their needs in hand, they consulted with Grover Loening, who at the time was the only prior designer of civilian amphibians with his 1920s' vintage Air Yacht. At the time, Loening was long out of business for himself having sold his company to Keystone Aircraft and was working as a consultant as well as an investor in Grumman Aircraft. Loening reviewed the syndicate's needs and created a preliminary design that was a twin-engine, high-wing amphibian. 

It was here where Loening's design for the syndicate and the preliminary design work at Grumman crossed paths. Perhaps it wasn't coincidence as some of the members of the syndicate as well as Leroy Grumman and one of the other founders of his company were all members of the same country club on Long Island, but any such record has been long lost to the mists of history. When Loening was asked by the Lloyd-Smith who would he would recommend to build their design, without hesitation Loening pointed the way to Leroy Grumman's office in Bethpage. It was a happy combination- ten of the wealthiest Long Island businessmen willing to pay for the plane they wanted and Grumman, eager to enter the commercial market, with a ready-made order for 10 aircraft. 

In addition to Wilton Lloyd-Smith, a prominent New York lawyer, the other members of his syndicate who ordered the first production versions of the Grumman Goose included Henry S. Morgan (founder of Morgan Stanley), Marshall Field (of the department store fame), E. Ronald Harriman (philanthropist and investment banker), C.W. Deeds (head of United Aircraft, predecessor to Pratt & Whitney), Robert McCormick (owner of the Chicago Tribune), Boris Sergievsky (head test pilot for Sikorsky Aircraft) and C.V. Whitney (one of the founders and investors of Pan American Airways). With such prominent businessmen ordering the Grumman Goose, the project was accorded top priority and the prototype first flew on 31 May 1937. With a few adjustments and modifications, the first Grumman G-21A Goose was handed over to Wilton Lloyd-Smith on 3 July 1937 for a price of $60,000. 

The Goose was an immediate success and the need for more capital to expand the Bethpage production line for the aircraft resulted in Grumman registering with the Securities and Exchange Commission for the public sale of company stock and listing on Wall Street. The connections made with Lloyd-Smith's syndicate in bringing the Grumman Goose to fruition paid off handsomely for Leroy Grumman's small company with hundreds of G-21s built for both private owners, airlines and military air arms worldwide. The sales of the Goose helped Grumman invest heavily in its next Navy carrier fighter which first flew as a prototype in 1937. The XF4F-2 would later become famous during the Second World War as the F4F Wildcat. 

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p92-101.