Bell YAH-63
| Bell YAH-63 | |
|---|---|
 YAH-63 prototype 001 |
|
| Type: | Prototype of an attack helicopter |
| Design country: | |
| Manufacturer: | |
| First flight: |
1st October 1975 |
| Commissioning: |
Flight tests ended in 1976 |
| Production time: |
Was never mass-produced |
| Number of pieces: |
3 |
The Bell YAH-63 (manufacturer designation "Model 409") was a prototype for the "Advanced Attack Helicopter" program (AAH) of the US Army . In flight tests, the YAH-63 was subject to the YAH-64 from Hughes , from which the AH-64 Apache later emerged.
history
AAFSS program
In the mid-1960s, the US Army initiated the AAFSS ("Advanced Aerial Fire Support System") program, from which the AH-56 Cheyenne emerged . This should primarily be used for anti-tank defense, a task that the AH-1G Hueycobra took over as an interim solution in the Vietnam War at that time . The army command, however, realized early on that the model was unsuitable for protecting Western Europe from the large tank units of the Warsaw Pact .
In 1972 the Army conducted an evaluation of the Bell 309 KingCobra , Lockheed AH-56 Cheyenne, and Sikorsky S-67 models . In the flight test, which lasted until July 1972, it was concluded that no type would meet the requirements. As a result, the Cheyenne program was canceled in August 1972, also due to technical difficulties and the questionable "high-speed nosedive concept".
AAH program
Since there was still an urgent need for an anti-tank helicopter after the failure of the AAFSS program , the AAH ("Advanced Attack Helicopter") program has now been initiated. Short-term considerations of purchasing an anti-tank aircraft instead of a helicopter were quickly discarded, as otherwise the US Air Force would have intervened, which at that time had such a model ( A-10 Thunderbolt II ) in development.
As a requirement of the new model of the AAH program, the Army stipulated that the helicopter of the AH-1 Cobra must be superior in terms of firepower, flight performance and operational range. In order to save development and operating costs, it was decided that the General Electric T700 engines of the "Utility Helicopter" program (from which the UH-60 Black Hawk later emerged) should be used. A 30 mm on-board cannon and 16 BGM-71-TOW anti-tank missiles were to be installed as armaments . This requirement was later changed and it was now demanded that the laser-guided AGM-114 Hellfire missiles , which were still under development , be used. These showed a greater range and effectiveness.
Bell, Boeing-Vertol (together with Grumman), Hughes, Lockheed and Sikorsky submitted proposals for the AAH program. In June 1973, Bell and Hughes were selected as finalists and were awarded contracts to build two prototypes each .
Flight testing
Although the YAH-63 adopted many of the design elements of the Cobra to reduce costs (narrow, long fuselage, tandem arrangement of the crew, stub wings, etc.), it was still an independent model. Special features were the tandem nose landing gear, an unusual vertical stabilizer and the three-barreled XM-188 30mm cannon. It was also unusual that the pilot sat in the front seat (for which the cockpit windows were adapted). The background was that the pilot, as part of the operational concept in the wooded areas of Western Europe, needed a better overview in order to be able to fly “in the treetops”. In order to ensure that the YAH-63 can be carried by air, the rotor mast could be lowered and the landing gear partially retracted. This served to reduce the height of the machine.
The first prototype of the YAH-63 (S / N 73-22246) made its maiden flight on October 1, 1975. It crashed in June 1976. Since the flight program with the second prototype (S / N 73-22247) could not be carried out alone, Bell converted a static break cell into a third prototype.
In December 1976, the YAH-64 was selected as the winner of the AAH program and developed into the AH-64 Apache. As a reason for the decision, the Army named the four-blade rotor design of the YAH-64, which was considered to be more bulletproof than the two-blade rotor of the YAH-63. Overall, the YAH-64 was considered to be safer, both in terms of chassis stability and cockpit armor. Furthermore, it was believed that the development potential of the YAH-64 was better, due to the higher payload. Some observers believed the decision was also politically motivated, as the US Army wanted a clearer move away from the AH-1 Cobra.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 |
| length | 13.6 m |
| Rotor diameter | 14.6 m |
| height | 4.1 m |
| Rotor area | 168.1 m² |
| Empty mass | 2993 kg |
| Max. Takeoff mass | 4500 kg |
| Engines | two General Electric T700 turbines with 1680 hp each |
| Top speed | 338 km / h |
| Range | 587 km |
| Max. Altitude | 3720 m |
| Max. Rate of climb | 8.2 m / s |
