Group 4 ­ Austere Field Light Attack Aircraft

In the past decades warfare has changed. Where first the balance of power, resources and tactics were more even, now large differences exist. Most aircraft that perform close air support missions, like the F-16 Fighting Falcon and the A-10 Thunderbolt, are not designed for these asymmetric scenario’s. The F-16 was designed for air superiority. Nowadays this plays a smaller role as opponents have a smaller or no air force. The A-10 was designed for assault on heavily armed vehicles. However opposing ground forces are also less heavily armored. Thus, the A-10 now is used against infantry and small buildings. To ensure these fighter and attack aircraft are still used, they were turned into multi role ground strike units. Helicopters, like the AH-64 Apache, can also perform close air support missions, but need more maintenance than aircraft, and are more susceptible to ground attacks. The under-utilization of military aircraft, and limited usability of helicopters, led to the need for smaller, purpose-build light attack aircraft. Mission Objective The objective is to design an affordable light attack aircraft that can operate from short, austere fields near the front lines in order to provide close air support missions to ground forces at short notice. Furthermore, the light attack aircraft shall complete missions that are currently only performed by attack helicopters. The design mission of the aircraft is stated as follows: carry 3 000 lbs of armament, have a warm-up and taxi of maximum 5 minutes, take-off from an austere field and clear a 50 ft obstacle in less than 4 000 ft. The aircraft shall cruise 100 nmi at a minimum altitude of 10 000 ft, and descend to 3 000 ft, within 20 minutes. After the cruise phase, the aircraft shall be able to loiter at 3 000 ft for 4 hours. After this, a return cruise, landing, taxi/shut-down shall be performed with the same conditions as before, with sufficient reserves for a climb to 3 000 ft and loiter for 45 min. In a threat analysis it was determined that the aircraft should survive handheld weapons and anti-aircraft gun fire, other threats have been identified as well. System Design A first and second order sizing was done in the engines are running, in order to decrease order to determine the weight and size of the down-time. For transport of the aircraft to the aircraft. The OEW and MTOW were deter- front line, it was chosen to deliver the aircraft mined to be 7.0 and 13.7 tons, respectively. A in a shipping container as this will be the most trapezoidal, dihedral, mid-wing configuration cost effective method of transportation. In or- was chosen with double slotted Fowler flaps der to fit into a container, the wings and tail and ailerons in order to satisfy the roll require- cone have to be disassembled. A market and ment set by the MIL-specifications. An H-tail cost analysis were carried out in order to deter- was chosen for redundancy, the elevator and mine the return on investment (ROI), a ROI rudder were sized for static and dynamic sta- of 10% at a price of 10.96 mln$ with a sale bility in all flight conditions. Between the wing volume of 830 units was calculated. and tail, two turbofan engines were placed. The heat signature of the engines will partly be cov- ered by the H-tail. The handling qualities were determined for this aircraft as well, the goal was to reach level 1. The fuel, hydraulic and electrical system were designed with redun- dancy in mind. A key challenge on an austere field are the operations and logistics. For oper- ations, it was decided to enable the aircraft to "hot-pit" refuel, i.e. refuel and rearming while

Delft University of Technology Design Synthesis Exercise 2020