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Stroukoff YC-134

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Designed as a prototype in 1956, the Stroukoff YC-134 was based heavily on the C-123 Provider. The United States contacted Stroukoff to try and develop an improved version of the aircraft, combining features that the Stroukoff Aircraft Corporation had developed for the YC-123D and YC-123E.


Stroukoff's work with the C-123

In 1956, the Stroukoff Aircraft Corporation had already gained much experience working on the C-123 Provider, having completed two contracts based on that airframe.

Its YC-123D had introduced a Boundary Layer Control (BLC) system to the C-123B. This system forced pressurized air over the upper wing surfaces of the airplane, making the wing work as if it were flying at much greater airspeed. This greatly improved landing and take-off performance, gross weight, and lowered the C-123's stall speed.

The YC-123E had been another experiment in improving the C-123's ability to operate where ever it might need to, introducing Stroukoff's own Pantobase system. The system comprised of two high-stress skis fitted to the lower fuselage and wingtip mounted floats, along with sealing the fuselage itself. This gave the YC-123E the ability to operate on water, as well as, ice and snow, and with the BLC from the previous YC-123D, the new aircraft could effectively be operated from almost any runway surface available, and ones of extremely short length.

For more information see the C-123 Provider Main Article

The YC-134

The product of a US Air Force contract in 1956, a single C-123B from the -CN production block (serial 52-1627) was modified by Stroukoff Aircraft to become the YC-134. This aircraft was heavily modified with the following new features:

  • New Engines: The YC-134 was equipped with two 3,500 hp Wright Turbo Compound R3350-89A radial engines, turning four-blade, thirteen foot Areoproducts constant speed fully-feathering propellers.
  • Improved Control Surfaces: The YC-134's stabilizers were given end plates to improve directional stability. This gave the aircraft its distinctive three tail look.
  • Improved landing gear: While the nose gear from the C-123B was retained, the both main gear were given a third wheel to improve weight distribution.
  • A Wet Wing: Fuel was no longer housed in the rear of the engine nacelles, but in an expanded center-wing fuel tank. In addition two plumbed hardpoints for 550-gallon drop tanks were also added to each wing.
  • Stroukoff's BLC and Pantobase: the YC-134 was fitted with Stroukoff's own BLC and all three aircraft had they been delivered were to have been fitted with the Pantobase equipment designed for the YC-123E.

These features gave an empty weight increase over the C-123B from 31,058 lb to 37,965 lb, and a maximum loaded weight increase from 60,000 lb to 74,700 lb. The aircraft's cruising speed was 219 mph, compared to the C-123B's 190 mph, and the YC-134 had a 1,600 mile range with a 24,000 lb payload. The BLC allowed the YC-134's take-off distance to be shrunk to from 1,850 feet to 750 feet, very similar to that of the YC-123D. The US Air Force, however, deemed that the YC-134 did not offer substantial improvement over the C-123, nor did it have a requirement for a piston-engined amphibious assault transport, and decided to purchase the Lockheed C-130.

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Designation sequence (USAF): C-131 - C-132 - C-133 - C-134 - C-135 - C-136 - C-137