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My interest in turbo-prop conversion is from a skydiver's perspective. I have jumped several of the conversions mentioned earlier. The best skydiving pilots run engines until scheduled overhauls, then many replace stock engines with more powerful, after-market, STCed engine conversions. As old radial engines wore out and spare parts got scarce, many jump-planes were converted to turboprops.
I have a few hundred jumps out of the (Beech 18 tail-dragger) Westwind Beech that worked at Hinckley, Illinois back during the early 1990s.
A Beech 18 conversion (Westwind 4?) sits behind the museum at Victoria International Airport (B.C. Canada). With PT-6A engines, tri-gear and a single rudder, it does look like a "poor man's King Air", but all that labout probably cost almost as much as a King Air ... similar to the Beechcraft Duke with PT6A engines.
On that note, the first Beechcraft King Airs were a batch of U-21s built for the US Army. They were un-pressurized (square windows) Queen Air airframes modified with a swept fin and PT-6A-20 engines. A few of those (non-certified military pattern) PT6A engines were installed in Murphy Moose kit planes. Mooses (plural ?) have been powered by a wide variety of engines: Lycoming and Continental flat 6s, Vedeneyev radials and turboprops.
The museum at Victoria Airport is only a short distance from where Viking builds new Twin Otter 400s. During August 2015, they had 4 shiny new Twin Otters in the final stages of fitting-out for customers. One sat on a huge set of Aerocet wheel-floats.
Twin Otter trivia: several skydiving centers brag about their "Super Otters" which are DHC-6-200 or -300 re-engine with PT6A-27 or -35 engines. Most of the conversions were done under one-time-only FAA 337 forms.
The first DHC-4 Cariboo conversion to PT6A engines was done in Gimli, Manitoba. It flew well, but the designer's son crashed the prototype when he forget to remove control locks (pretty scary video!). Pen bought the rights to the Turbo-Cariboo conversion. I also found the remains of a Saunders ST-27 or ST-28 (?) at Gimli in 1992.
Republic Seabee conversion C-GNVS sat idle at Pitt Meadows Airport (B.C. Canada) for a decade. Pilot Andrew Whyte (?) said that it flew great, but guzzled fuel like crazy! The regular belly fuel tank was supplemented by extra fuel tanks in both wing roots. With full fuel, it could only carry two pilots ... no cargo. With its pointy nose and plenty of extra fairings (aft end of cabin and tail surfaces) it barely looked like a Seabee. The turbo-Seabee was a test-bed for an un-built new amphibian.
At one point we had Seabees with 4 different engines at Pitt Meadows: the original Franklin, a Lycoming GO-480 conversion, a Corvette conversion and the Turbo-Seabee. Andrew Whyte described the Corvette as the best combination of power and fuel consumption.
Another trivia point is that the Soloy Conversion is the only version of the Cessna 207 that can fly on floats, because it is the only version with enough horsepower to lift off from lakes.
I have a few jumps from Soloy Cessna U206 conversion and love the cargo door. The Soloy 206 climbs like stink .... and it does stink of turbine exhaust! Soloy also modifies the wing when they install Allison of Rolls-Royce 250 engines. The Soloy U206 is my second-favorite Cessna jump-plane after the 208 Caravan.
Stock Caravans climb slowly with stock 600 or 675 horsepower engines. Cessna eventually certified an 848 (?) horsepower version of the PT6A-140 engine, but impatient a variety of conversion companies (Aero Twin, Blackhawk and Texas Turbines) obtained STCs to install more powerful engines. Texas Turbines has STCs to install Honeywell engines in Caravans.
My old friend Van Pray Junior is in the later stages of obtaining an FAA Supplementary Type Certificate to install a PT6A-20 engine in a Cessna U206 jump-plane. His conversion resembles the Golden Eagle (?) conversion for Cessna 210, but VP Jr. started from scratch.
Has anyone mentioned the Soloy conversions of Bell 47 and Hiller helicopters?
Also note that Pilatus Porters were built with at least three different turbo-prop engines: Astazou, PT6A and Garrett. Garrett TPE-331-1-101F engines were only installed in AU-23 Porters license-built by Fairchild Hiller and most of those flew missions for Air America/CIA in the jungles of Laos and Cambodia. After the war, they were sold to the Royal Thai Air Force, but during the 1990s, a few were re-imported to the USA, over-hauled and worked at sport parachute centers in Washington State. One of those Porters crashed in Chilliwack, B.C. when a pre-maturely deployed parachute tore the tail off. Fortunately, every one on board survived because they wore parachutes .... even the pilot!
Fairchild Porters competed directly with Helio Couriers and Helio Stallions for US Army and CIA contracts. The AU-24A Helio Stallion started as a turbo-conversion of the (piston) Twin Courier, but quickly evolved into a much larger airplane powered by a single PT6A engine. A single Helio Stallion hauled skydivers in the USA until it crashed at Perris Valley, California killing pilot Jim Lowe.
The Fletcher Air Parts FU-24 and Cresco agricultural airplanes evolved into the current-production Pacific Air Craft 750 with a PT6A engine and large-diameter fuselage. The PAC 750 has been marketed as the "first airplane designed specifically for skydivers" .. funny how the PAC 750 was updated at the same time that a lower-cost, but larger-volume fertilizer was introduced to New Zealand??????
Hah!
Hah!
On a historical note: I have never seen a PBY Catalina flying boat converted to turboprops.
The Catalina's replacement: Canadair CL-215 water-bomber was designed with radials because they were so inexpensive during the 1960s and 1970s, but as radial spare parts dried up, Canadair converted the production line to CL-415 turboprops.
On another historical note, Canadair built the Bristol Britannia airliners and air-freighters with stock turbo-props, but de-converted the airframe to Wright radials when they designed the CP-??? Argus. Back during the 1950s, radial engines offered better fuel economy. An Argus set a record by staying on patrol for something like 24 hours (before the RCAF adopted inflight refueling). Ironically, the Royal Canadian Air Force eventually (1980s) replaced their worn out Argus piston-pounders with Lockheed P-3 Orions powered by Allison turboprop engines. Fortunately, by the 1980s, turboprops had developed much better specific fuel consumption.
I have a few hundred jumps out of the (Beech 18 tail-dragger) Westwind Beech that worked at Hinckley, Illinois back during the early 1990s.
A Beech 18 conversion (Westwind 4?) sits behind the museum at Victoria International Airport (B.C. Canada). With PT-6A engines, tri-gear and a single rudder, it does look like a "poor man's King Air", but all that labout probably cost almost as much as a King Air ... similar to the Beechcraft Duke with PT6A engines.
On that note, the first Beechcraft King Airs were a batch of U-21s built for the US Army. They were un-pressurized (square windows) Queen Air airframes modified with a swept fin and PT-6A-20 engines. A few of those (non-certified military pattern) PT6A engines were installed in Murphy Moose kit planes. Mooses (plural ?) have been powered by a wide variety of engines: Lycoming and Continental flat 6s, Vedeneyev radials and turboprops.
The museum at Victoria Airport is only a short distance from where Viking builds new Twin Otter 400s. During August 2015, they had 4 shiny new Twin Otters in the final stages of fitting-out for customers. One sat on a huge set of Aerocet wheel-floats.
Twin Otter trivia: several skydiving centers brag about their "Super Otters" which are DHC-6-200 or -300 re-engine with PT6A-27 or -35 engines. Most of the conversions were done under one-time-only FAA 337 forms.
The first DHC-4 Cariboo conversion to PT6A engines was done in Gimli, Manitoba. It flew well, but the designer's son crashed the prototype when he forget to remove control locks (pretty scary video!). Pen bought the rights to the Turbo-Cariboo conversion. I also found the remains of a Saunders ST-27 or ST-28 (?) at Gimli in 1992.
Republic Seabee conversion C-GNVS sat idle at Pitt Meadows Airport (B.C. Canada) for a decade. Pilot Andrew Whyte (?) said that it flew great, but guzzled fuel like crazy! The regular belly fuel tank was supplemented by extra fuel tanks in both wing roots. With full fuel, it could only carry two pilots ... no cargo. With its pointy nose and plenty of extra fairings (aft end of cabin and tail surfaces) it barely looked like a Seabee. The turbo-Seabee was a test-bed for an un-built new amphibian.
At one point we had Seabees with 4 different engines at Pitt Meadows: the original Franklin, a Lycoming GO-480 conversion, a Corvette conversion and the Turbo-Seabee. Andrew Whyte described the Corvette as the best combination of power and fuel consumption.
Another trivia point is that the Soloy Conversion is the only version of the Cessna 207 that can fly on floats, because it is the only version with enough horsepower to lift off from lakes.
I have a few jumps from Soloy Cessna U206 conversion and love the cargo door. The Soloy 206 climbs like stink .... and it does stink of turbine exhaust! Soloy also modifies the wing when they install Allison of Rolls-Royce 250 engines. The Soloy U206 is my second-favorite Cessna jump-plane after the 208 Caravan.
Stock Caravans climb slowly with stock 600 or 675 horsepower engines. Cessna eventually certified an 848 (?) horsepower version of the PT6A-140 engine, but impatient a variety of conversion companies (Aero Twin, Blackhawk and Texas Turbines) obtained STCs to install more powerful engines. Texas Turbines has STCs to install Honeywell engines in Caravans.
My old friend Van Pray Junior is in the later stages of obtaining an FAA Supplementary Type Certificate to install a PT6A-20 engine in a Cessna U206 jump-plane. His conversion resembles the Golden Eagle (?) conversion for Cessna 210, but VP Jr. started from scratch.
Has anyone mentioned the Soloy conversions of Bell 47 and Hiller helicopters?
Also note that Pilatus Porters were built with at least three different turbo-prop engines: Astazou, PT6A and Garrett. Garrett TPE-331-1-101F engines were only installed in AU-23 Porters license-built by Fairchild Hiller and most of those flew missions for Air America/CIA in the jungles of Laos and Cambodia. After the war, they were sold to the Royal Thai Air Force, but during the 1990s, a few were re-imported to the USA, over-hauled and worked at sport parachute centers in Washington State. One of those Porters crashed in Chilliwack, B.C. when a pre-maturely deployed parachute tore the tail off. Fortunately, every one on board survived because they wore parachutes .... even the pilot!
Fairchild Porters competed directly with Helio Couriers and Helio Stallions for US Army and CIA contracts. The AU-24A Helio Stallion started as a turbo-conversion of the (piston) Twin Courier, but quickly evolved into a much larger airplane powered by a single PT6A engine. A single Helio Stallion hauled skydivers in the USA until it crashed at Perris Valley, California killing pilot Jim Lowe.
The Fletcher Air Parts FU-24 and Cresco agricultural airplanes evolved into the current-production Pacific Air Craft 750 with a PT6A engine and large-diameter fuselage. The PAC 750 has been marketed as the "first airplane designed specifically for skydivers" .. funny how the PAC 750 was updated at the same time that a lower-cost, but larger-volume fertilizer was introduced to New Zealand??????
Hah!
Hah!
On a historical note: I have never seen a PBY Catalina flying boat converted to turboprops.
The Catalina's replacement: Canadair CL-215 water-bomber was designed with radials because they were so inexpensive during the 1960s and 1970s, but as radial spare parts dried up, Canadair converted the production line to CL-415 turboprops.
On another historical note, Canadair built the Bristol Britannia airliners and air-freighters with stock turbo-props, but de-converted the airframe to Wright radials when they designed the CP-??? Argus. Back during the 1950s, radial engines offered better fuel economy. An Argus set a record by staying on patrol for something like 24 hours (before the RCAF adopted inflight refueling). Ironically, the Royal Canadian Air Force eventually (1980s) replaced their worn out Argus piston-pounders with Lockheed P-3 Orions powered by Allison turboprop engines. Fortunately, by the 1980s, turboprops had developed much better specific fuel consumption.
