Scaled Composites ARES - Aircraft Design

Aircraft Design

The ARES has quite unique shape compared to other aircraft. It incorporates canards which enable safer flight at low altitude. The canards serve as the pitch control and are designed so that the canard surface reaches critical angle of attack sooner than the main wings, protecting the aircraft from stall while full roll control is retained. The canards have a wingspan of 19.2 feet (5.85 m) and are swept 7 degrees forward so they can be placed behind the cockpit.

The main wing has a span of 35 feet (10.7 m) and a reference area of 191 sq. ft. (17.7 m2), not including the strakes. It is swept aft 16 degrees at the leading edge. The strakes are swept 49 degrees at the leading edge. These strakes, combined with a wet wing center-section area, form the bulk of the 2,200 lb (1000 kg, approximately 333 U.S. gallons) fuel capacity. The wing has conventional ailerons on the outboard trailing edge, and spoil-flaps (similar to the dive-brake flap) on the inboard trailing edges. The ailerons are actuated by push-rods, and the spoil-flaps are hydraulically operated.

Directional stability is provided by twin boom-mounted fins, each of 18 sq ft (1.7 m2). area. Each has a cable-actuated rudder at its trailing edge. The rudder actuation system also drives the full-time mechanical nosewheel steering for ground operations.

The engine inlet is another major unique feature of ARES. Since gun gas ingestion posed significant problems in other aircraft development programs (like A-10), the configuration of ARES was designed to avoid this problem: the engine inlet is entirely contained on the left side of the aircraft, and the gun is installed on the right side. The inlet has a circular cross section, and is straight into the fan face. The engine is mounted slightly transversely in the fuselage, with an 8-degree misalignment from the aircraft's longitudinal axis.

The engine exhaust is turned back to the longitudinal axis by a curved composite tailpipe. A composite tailpipe was to help get the gun recoil reaction closer to the aircraft lateral center of gravity (CG) location, the gun is sub-merged as deeply as practical into the right side of the fuselage. Also, the fuselage is not centered about the aircraft centerline, but is offset to the left by three inches. This results in the firing barrel of the gun being only about 18 inches from the lateral CG. This minimizes the yaw movement caused by the recoil of the gun.

The aircraft fuselage is almost completely made of fiberglass composite material installed over the foam core. The technique of making of composite aircraft fuselages has been perfected by Scaled Composites in previous aircraft.

To assure a low cost and high reliability of the components ARES primarily includes off-the-shelf aircraft systems. The engine is the Pratt and Whitney Canada JT15D with 2900 lb (13,2 kN) of thrust at sea level. The hydraulic system, used for spoiler flaps and landing gear actuation, uses a Piper Malibu hydraulic pump, which operates at 1500 psi. Instrumentation for the demonstrator consists mainly of standard general aviation equipment. In addition there is a head-up display which currently displays only a fixed reticle to aim the gun but is capable of displaying complete data range of F-16. The pilot seats in the Universal Propulsion Company SIIIS-3ER ejection seat with zero-zero capability.

The fuel system consists of auxiliary wing tanks feeding an armored, fuselage-mounted main tank, which sits just forward of the engine and behind the firewall. The main tank can feed the engine in all attitudes. This tank is continuously refiled from the main wing tanks with no fuel management duties required of the pilot. By feeding the main tank from the two auxiliary wing tanks, the size of the fuel tank in the fuselage was effectively halved, creating a large space behind the pilot empty of any tanks or other aircraft systems. This bay had no dedicated function on the demonstrator, but was intended to be left available for any additional equipment which the Army might wish to install in the production version.

The main flight controls are completely mechanical and the engine has a backup mechanical fuel control so the aircraft can retain control even if the electrical system fails. The controls were specially designed to minimize the forces on the stick.

Beside the GAU-12 gun there are additional pylons to carry another ordnance (Hydra 70 FFAR, for example).