Conceptual Design for a High-Speed UAV

We explored different aspects of aircraft design to fully define MUFASA. These include center of gravity (CG), wing bending, propulsion, sensitivity, and takeoff configuration.

Center of Gravity

Wing Bending

Propulsion

Sensitivity

Takeoff Configuration

Our takeoff configuration study compares two takeoff methods: landing gears vs launch lugs. Landing gears act as a suspension system for an aircraft, absorbing and dissipating the kinetic energy that the aircraft experiences. A launch lug is a small protruding solid that is attached onto the aircraft’s fuselage, and this solid is inserted into a launch rail to stabilize the aircraft during takeoff. The benefits and drawbacks of using each configuration were assessed through MUFASA’s speed, drag, takeoff distance, and range. Additionally, the cost and manufacturability of each configuration were considered.

We explored different aspects of aircraft design to fully define MUFASA. These include center of gravity (CG), wing bending, propulsion, sensitivity, and takeoff configuration.

The improvements our tools and studies provide fall under one or more of the following categories.

1. They streamline the conceptual design process.
2. They improve upon the accuracy of the previous analyses done.
3. They introduce a new aspect of the aircraft that is helpful to be analyzed.

A lot of the Python scripts we created fall under the first point. The CG and wing bending functions allow the conceptual design stage to be more streamlined. Alternative methods of analyses are laborious. For instance, SolidWorks and ANSYS models can be used to determine MUFASA’s CG and stress distribution, but making these models require a considerable amount of effort. The Python structure offered by our functions allow for easy re-calculations to MUFASA whenever geometry modifications are made.

Most of our work falls under the third and last point. The propulsion, sensitivity, and takeoff studies offer new ideas that were not explored back in V1’s conceptual design stage. For the propulsion study, we analyzed ramjets as a potential engine because of their suitability for supersonic flights; ramjets were never considered for V1. Moreover, a sensitivity analysis was never conducted during V1, and using a launch lug as MUFASA’s takeoff mechanism is a consideration exclusive to V2. 

We acquired our major specifications through our exploration of MUFASA’s center of gravity, wing bending, propulsion, sensitivity, and landing gear/launch lug configuration. These specifications are presented below.

Table 1: MUFASA’s Major Specifications

Parameter	Specification
Fuselage Length	2.1 m
Wingspan	1.07 m
Root Chord	1.25 m
Taper Ratio	0.072
Takeoff Weight	53 kg
Center of Gravity from the nose	1.09 m
Wing Bending Inertia	17.9 cm4 (Hollow); 171 cm4 (Solid)
Tip Deflection at 6g Load	3.06 mm (Hollow); 0.32 mm (Solid)
Engine Model	Turbojet: AMT Nike Jet Engine
Fuel Type	JP8
Maximum Thrust	675 N
Fuel Burn Rate at Maximum Thrust	0.033 kg/s
Maximum Speed	336 m/s
Maximum Range	319 km
Takeoff Speed	49 m/s
Takeoff Distance	145 m
Landing Gear/Launch Lug Configuration	Tricycle Retractable Landing Gear

To validate our design solution, we simulated MUFASA throughout a flight mission using SUAVE. This mission includes the takeoff, climb, cruise, and descent segments of the flight. Note that MUFASA climbs to an altitude of 10 km to reach its cruise segment.

Figure 1: MUFASA’s Flight Mission Divided into Segments

With our mission simulation, we acquired numerous values presented in the Specifications section: takeoff distance, takeoff speed, maximum range and speed, maximum thrust and fuel burn rate, etc. We compared the values from our conceptual build to the values from MUFASA V1 to assess the improvements. These are listed below.

1. The specific impulse (thrust-to-fuel burn rate efficiency) increased by 19%.
2. MUFASA V2 is 348% faster than V1.
3. MUFASA V2’s maximum range increased by 1040% from V1.
4. MUFASA’s takeoff distance decreased by 67% for V2.

Additionally, we validated the integrity of our wings through our wing bending study. We subjected MUFASA to the typical loads it would experience during flight and determined how much the wings would be affected under these loads. 

Figure 2: Sectional lift distribution across the wing (top left); Wing geometry broken into sections (bottom left); Hollow wing tip deflection (top right); Hollow wing factor of safety (bottom right)

From our studies, we determined that MUFASA V2 would have a tip deflection of no more than 3.06mm when subject to a 6g load, with a factor of safety of 5. The resulting tip deflection is less than 0.3% of the wingspan, indicating there will be minimal impact to the vehicle’s aerodynamics up to a 6g load. The results of our wing bending study confirmed that the MUFASA V2 wings are more than capable of withstanding all anticipated loading.

By simulating MUFASA throughout a flight mission, we determined its flight characteristics. These results quantify how much the changes we made improved MUFASA V1. Beyond the performance improvements, these simulations also shed light onto the structural integrity of our conceptual build. It provides assurance that MUFASA will not fail under the loads of supersonic flight.