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Executive DC-3 Conversions – Part 1

Original article from "The Legacy of the DC-3" book by Henry M Holden 1996 Wind Canyon Publishing Inc.

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It is not generally well known but between February 1941 and December 1946, the Douglas Aircraft Company (DAC) delivered 15 specially customized executive DC-3s to corporate owners like Texaco, Cities Service Oil Corp, Randolph Hearst and Gulf Oil. These airplanes would be the pace-setters for a new trend in corporate aviation after WW2. As the civilian air transport market regained its prewar popularity, the demand for comfortable transportation grew. The bare basis of the ex military C-47 airframe was popular, but it was not a comfortable ride. In 20 days the DAC could convert a C-47 back into a commercial plane. After removing all military hardware, carpeting, air conditioning and a passenger interior was installed. By 1947 more than 500 conversions were flying in the US and several hundreds more in Europe.

The nation′s peacetime economy was booming and Donald Douglas prediction had come true, speed was essential to business. Sales executives, who were busy darting around the country, often could not get an airline seat. As a result they spent hours waiting in airports. Corporate accountants began to see the value of a company owning its own airplanes. At the time, Newsweek magazine reported that Montgomery Ward purchased two executive DC-3s, which saved 58 % of its staff travel time.

The DC-3 changed the face of corporate America. Executives were now able to travel anywhere, at any time to conduct business. An absence of any other aircraft developments for business travel, made the DC-3 conversion very attractive for buyers and sellers. Companies like Garrett Corporation AiResearch of Los Angeles and Remmert-Werner of St Louis transformed the Gooney Bird into flying executive suites. There were more than 20 Supplemental Type Certificates (STC’s) issued for these DC-3 conversions. When the transformation was complete the DC-3 sold for between 150.000 and 260.000 US dollars.

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Remmert-Werner converted their first DC-3 in December 1946 and by early 1950s, they had completed more than 200 airframes. Their modification package was engineered for the Twin Beech, Lodestar and the DC-3 and consisted of many changes, for instance; the heating system, outer wing tanks, landing gear doors, air-stairs, one-piece "bird-proof" cockpit window, large size cabin window′s and many more technical innovations. They also offered the Deluxe "Super-92" DC-3 which included a whole range of changes/improvements for the cabin and cockpit, which included a full VIP interior and a whole range of new cockpit instruments.
Toronto (Canada) based Millardair also modified several of the Remmert-Werner DC-3s with their own modification, changing the engine cowlings and MLG doors and calling it a "Speed Kit".

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AiResearch gave its customers a first-rate package for their money which was called "The Maximizer Kit"*. They upgraded the Pratt & Whitney engines by 150 Hp. This boosted the cruising speed by 20 miles per hour and in addition provided for improved safety due to increased single-engine performance. This also permitted them to add 200 gallons of fuel in the outer wing panels.
Special writing desks, swivel chairs, refreshment nooks, special fabrics and four panoramic windows were part of the interior package.
*The Maximizer Kit, integrated streamlined engines cowlings, baffles, oil cooler ducting, exhaust redesign with adding wheel well doors to improve the aircraft performance. The short exhaust stack, carried a Supplemental Type Certificate (STC) #SA2-59 mod which was issued in June 1959.

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This kit also provided wheel well doors and additional hydraulic actuating cylinders for the main gear, a modified hydraulic panel and specialized oil cooler scoops. The gear retraction time improved from 21 seconds to 8 seconds. Some customers added (or changed), the spinner & engine cowling configuration for the "Miner′s Aircraft & Engine Service Inc" variant. This gave the Maximizer kit a very unique shape. One of those DC-3s with such a kit installed is the "Sears Roebuck & Co" N78SR which is on display at the Iranian Aerospace Exhibition Center, Mehrabad International airport Tehran as EP-TWB.

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Another different spinner ad-on combination was done on the corporate C-53/R4D-3 Skytrooper N242SM (ex N596AR) which is on display at the Museum of Flying at Santa Monica municipal airport, the birthplace of many DC-3s. According to the history books she was fitted with a larger R-2000 engine back in 1957. She retains the original Maximizer kit and incorporated a huge front spinner possible for better cooling for the bigger engine.

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Pan American Airways developed a HiPer DC-3 (High Performance) package in 1952. They added the new Pratt & Whitney R-2000 engines, which replaced the standard R-1830s, and provided 1450 hp, new props and redesigned exhaust, air intakes and fire extinguisher. They also modified the ailerons which provided for greater stability and control in a stall. The actual engineering & work was done by HAYES Aircraft out of Birmingham, Alabama. The first unit was ordered by Panagra (partly owned by Pan American). The HiPer DC-3 greatly improved the aircraft′s performance on the hot and high altitude airfields, across much of Central and South America. Currently only one HIPER DC-3, N62CC "Virginia Ann" remains airworthy in the US and it belongs to Mission Boston D-Day LLC.

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Even the Douglas Aircraft Corporation Company went into the executive DC-3 conversion business. They bought 40 surplus C-47s and created their own executive model, installing a lounge, galley and writing desk. The first a/c flew in 1946 and was sold immediately for 120.000 US dollars.

The Executive Aircraft Service of Dallas came up with a unique idea for the DC-3 belonging to International Petroleum. They reconfigured it to carry passengers and cargo in a unique arrangement which provided a quick change from cargo to passenger layout. The main C-47 cargo door featured a smaller passenger door with an air-stair. It also featured a removable bulkhead to separate the passengers from cargo, when the a/c flew in a combi configuration.

The L.B. Smith Company of Miami also came up with a unique idea. They stretched their DC-3s by adding 8 feet of cabin space within the existing fuselage, reclaiming space form radio racks, junction boxes and circuit breaker panels. Equipment was relocated under the floor, under sofas, chairs and tables. The interior was re-worked in order to resemble a typical living room and added four large panoramic windows also known as ‘View-masters’. DC-6 style windows were installed in the cockpit, which eliminated the problem of leaks and finally, they enclosed the wheel wells with fiberglass doors. Selling price was 275.000 US dollars, 2.5 times the original cost of a DC-3.

During the early 1960s the ‘Cummins Engine Co Inc’ based in Colombus Indiana also offered a DC-3 modification. The corporate package included many modifications: square and shorter wingtips; different wing-body fairings; speed cowls and spinners; MLG doors, retracting tail-wheel, Pratt & Whitney 1830-75 engines, a radar equipped nose, View-master windows, enlarged cockpit, DC-4 hydraulic system, and a relocated radio rack. It is not known exactly how many they converted but recently one aircraft, the corporate N84KB (c/n 9040) was rescued from lengthy storage at a small airstrip in Adair Village Oregon and flown to the Basler Turbo Conversions location, Oshkosh in 2018.

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The Transair "Dakmaster" kit offered different wheel-well doors to close the landing gear bay; this would reduce the a/c drag by 6.25%, which gave a sizeable increase in performance. The engines were up-rated to in crease the cruising speed with 18mph. The propellers were modified, this added 3mph to the speed. The hydraulic system was re-worked enabling the undercarriage to be retracted in half the normal time. The a/c brakes were up-rated to Goodyear disc brakes. All the combined modifications gave the DC-3 an improved take-off and climb performance and an overall increase of a total of 30mph.

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Canadair C-47 Conversion

Canadair acquired all of the Douglas C-47-type jigs, tooling and spares that had been virtually discarded by Douglas at war’s end. This provided Canadair with a huge opportunistic leap into the field of used, reconditioned aircraft, as they converted a multitude of war weary C-47s, C-49s, C-53s and ex-RAF Dakotas, into pristine, almost as good as new, DC-3s for the growing commercial aircraft market. A few corporations purchased some of the refurbished DC-3s for use as executive transports, having interiors configured with all the amenities of the corporate lifestyle. Canadair also became the sole source and provider of the huge inventory of spare parts, which they provided at low cost to DC-3 customers to support their aircraft worldwide for years to come.

The Scottish Aviation Limited based at Prestwick airport also converted the Douglas Dakota into luxury airliners. Their facility was fully equipped to undertake repairs, overhauls and conversions of airframe, engines and ancillary equipments. A standard C-47 conversion typically included a full VIP interior, carpets, curtains, swivel seats, benches, work cabinet, side mounted sofa′s ect. The company brochures featured different categories: such as a freighters conversion, standard 21-seater airline, De-Luxe 21 seater airline and the Executive configuration.

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Info credits - - Photo credits: Alex Mc Phee brochures & photo collection, and co-editor Andre van Loon

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