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 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.

Having built up its experience base with the local assembly of the Fouga CM-170 Magister jet trainer in the late 1950s, Israeli Aircraft Industries (IAI) used the Magister as the basis for its first jet design, the B-101 business jet. The B-101 combined the wings and V-tail of the Magister with a new fuselage and external jet nacelles on the aft fuselage. However, it was soon realized that the target cruise speed of Mach 0.8 wasn't possible with the wings of the Magister. Five different design configurations followed that included a T-tail, swept wings and at one point, a trijet, but the project was eventually cancelled in May 1963.

IAI would get back into bizjets again several years later when Rockwell Standard acquired Jet Commander of Oklahoma. As Rockwell already owned North American Aviation that produced the Sabreliner, the US Department of Justice required that Rockwell had to sell one of the two business jet concerns to comply with anti-trust statutes. As the US military was already operating the Sabreliner as the T-39, the complete Jet Commander program was offered for sale including 49 unsold airframes. In September 1967 IAI was the winning bidder and the Jet Commander evolved into the Westwind.

The Westwind led to the improved IAI Astra which first flew in March 1984 and in turn with cooperation with Yakovlev, led to the IAI Galaxy which first flew in December 1997. In 2001 General Dynamics' Gulfstream Aircraft purchased the Astra and Galaxy programs and they were were rebranded as the G100 and G200 with the G150 a further development that launched in 2002 of what was the IAI Astra.

Source: Air Enthusiast, September/October 2003. "Golden Heritage- Israeli Aircraft Industries at 50" by Shlomo Aloni, p17-30.

In the 1980s US entrepreneur Dennis Washington found himself frustrated that his Gulfstream II jet could not fly coast-to-coast without refueling and didn't want to have to buy a newer version of the Gulfstream to get that range. He turned to a friend who was a long time aviation industry insider, Joe Clark, who then turned to a former Boeing aerodynamicist, Bernie Gratzer. They created a blended winglet and used Dennis Washington's Gulfstream II as the testbed for their work.

Confirming the predicted savings, the team then had to sell other Gulfstream owners on the idea which came after the setting of several world records on a blended winglet-equipped Gulfstream.

The group's big break came in 1997 when Borge Boeskov, president of Boeing Business Jets, met with Joe Clark about installing the blended winglets on the BBJ. The trials would be conducted on a Hapag-Lloyd 737-800 for six weeks at Clark's expense. If the trials were successful, then the winglets would be standard fit on all BBJs and Hapag-Lloyd kept the winglets on their loaner as well.

The rest, as we all know, is history!

Source: Airliner World, March 2009. "API: Performance Enhancing Winglets" by Tony Dixon, p58-59.

Three Gulfstream V jets based at Andrews AFB flying for the US Army's Priority Air Transport (and designated C-37A for the G500 and C-37B for the G550) have unique serial numbers denoting dates of historical significance in the history of the Army.

The first aircraft, a C-37A, has the serial number 05-1944 to commemorate the D-Day landings on the Normandy coast during the Second World War.

The second aircraft is also a C-37A and has the serial number 02-1863 to commemorate the Battle of Gettysburg in the American Civil War.

The last aircraft is a C-37B and has the serial number 04-1778 to commemorate the passage of an act of Congress that created the Army.

Source: Air Forces Monthly, May 2008. "Distinguished Airlift" by Dave Willis, p80.

Unique amongst airborne early warning aircraft, the IAI/Elta Nachshon Aitam uses two different transmission bands for its radars- L-band for the conformal side antennas and S-band for the nose and tail antennas. Utilizing a Gulfstream V airframe, the use of a different frequency band for the nose and tail antennas allows for a smaller antenna that results in less performance penalties on the overall airframe.

Source: International Air Power Review, Volume 25. "Technical Briefing: IAI/Elta Nachshon, Israel's special mission Pioneers" by Shlomo Aloni, p83-84.