The Kestrel was an all purpose combat helicopter designed by Triton Dynamics for the Coalition of Ordered Governments (COG). First entering service 16 years before the end of the Pendulum Wars (17 BE), the Kestrel is notable for the influence it had on later helicopter design as opposed to its combat record.
With no end to the Pendulum Wars in sight and the Valkyrie helicopters that were currently in use showing their age, the COG issued a request for proposals for a new all purpose infantry support, light attack, and transport helicopter. In addition to these requirements, the design had to be far more stable in low level flight than the Valkyrie. Several manufacturers’ submitted designs and the entries from Triton Dynamics and the Aktherton Corporation were selected as finalists, despite considerable differences between the two. Aktherton had proposed a conventional single rotor design with an upgraded avionics and fly-by-wire system. Triton Dynamics produced a radically different coaxial rotors design. This was revolutionary at the time; there was no other combat aircraft that used this system, one that had only been implemented on a few experimental civilian aircraft, in any of the warring nations.
Regardless, each company built prototype helicopters and went through a flight test program. After evaluating the trial results, the Kestrel was selected as the winning design, much to the surprise of the Aktherton design team. The Kestrel went through a short period of further refinement before being approved for production. However the original contract for 500 aircraft was reduced to 350. The reasoning for this was that the COG wanted to ensure that pilots and mechanics were properly trained and prepared for the new design before large quantities were being produced.
The Kestrel was designed to be small, fast, and agile to improve survivability and lethality, and yet durable enough to act as a multi-role support craft. For minimal weight and size (thus maximal speed and agility) it was to be operated by a single pilot only. Triton Dynamics concluded after thorough research of helicopter combat during the many previous years of war that a typical mission doesn't simultaneously demand navigation, maneuvering, and weapons operation of the pilot; and thus with well-designed support automation a single pilot can indeed carry out the entire mission alone.
The most recognisable feature of the Kestrel was the revolutionary counter-rotating co-axial rotor system, which removed the need for the entire tail-rotor assembly and improved the aircraft's aerobatic qualities -- it could perform loops, rolls, and “the funnel” (circle-strafing) where the aircraft maintains a line-of-sight to target while flying circles of varying altitude, elevation, and airspeed around it. Using two rotors meant that a smaller rotor with slower moving rotor tips can be used compared to a single rotor design. Since the speed of the advancing rotor tip is a primary limitation to the maximum speed of a helicopter, this allows a faster maximum speed than contemporary helicopters. The elimination of the tail rotor is a significant advantage because the torque-countering tail rotor can use up to 30% of engine power. Furthermore, the vulnerable boom and rear gearbox are fairly common causes of helicopter losses in combat; the Kestrel's entire transmission presents a comparatively small target to ground fire. Triton built the co-axial drive assembly is built to survive hits from 20 mm ammunition like the other vital parts of the helicopter. This design also allows the aircraft to be fairly immune to wind strength and direction, and to have an unsurpassed turn rate.
The main weapons of the Kestrel are two forward mounted 12.7mm heavy machine guns. These allow the Kestrel to attack infantry, unarmored or lightly-armored vehicles and boats, light fortifications, and low-flying aircraft. Despite some concern from the pilots that this round would not have adequate power, both the COG and Triton design team felt that it would be sufficient for the majority of combat situations.
In addition to the 12.7mm guns, the helicopter equipped two 7.62mm light machine guns on either side that could be operated by passengers or dedicated gunners. These were designed solely for strafing infantry, and were even by the standards of the day, considerably underpowered. Triton claimed that the helicopter was not designed as a tank killer or heavy attack craft, and that greater armament was not needed.