AE420

Concepts

Conceptual design is the beginning of all design projects, this one is no different. Shown in the picture is a table of the models I made for all concepts from the group members. The pros and cons of each design are evaluated and documented in the design notes below. The decision matrix refers to Dr. Gudmundsson's book "General Aviation Aircraft Design." The table used is modified to fit the mission of this aircraft, most of the equations and tables used in this project were developed in the same fashion.

Constraint Analysis

Different tasks were assigned to the team members. On this page, only the tasks I have completed are explained. (The specific roles are listed in the design note below.) To determine the optimal design points, constraint curves were made using the flight conditions, including estimated weight and drag coefficients. The constraints help to find the thrust-to-weight ratio needed and the smallest possible wing area that meets the requirements.

CAD Practice

While waiting for the progress, I was also sharpening my CATIA skill by sketching a model of Gulfstream 280. The model is not accurate, but I was able to experiment with my concepts of easily making spar caps in CATIA. I was able to finish models in a much shorter time because of it.

First Iteration

The first iteration was quickly completed with the information obtained in the design process. As the CAD designer, I was also responsible for designing the size and geometry of the wing and fuselage because I can provide the volume and wetted area once I finish sketching.

The fuselage was sized to meet the requirement of comfortably carrying 12 passengers,2 flight crews, and 1 flight attendant. Positioning of the fuselage to the wing and stabilizers was based on experience as the detailed weight analysis was not available yet.

The wing planform was designed based on the conditions of the optimal point on the constraint diagram. The Yehudi flap was planned in the beginning to decrease the required lift coefficient inboard, thus reducing the upper surface Mach number near the fuselage. The taper ratio (TR) without this device is 0.3, commonly known as the TR with minimum induced drag. The added Yehudi flap was counted into the wing area for wing loading calculation, for the minimum frictional drag.

Engine Mock-up

The 3D mock-up of the selected engine was modeled in my spare time. Due to the lack of public information, this model was made using pictures and information on Wikipedia. It was made to help to visualize our engine installation plan and improve the level of detail.

Fuselage Shape Touch-up

The shape of the fuselage is then modified after the tail length and engine dimensions are defined. Attempts to avoid tail-strike and compressibility effect related issues were implemented.

Cockpit

The cockpit dimension was planned out early following "General Aviation Aircraft Design." The nose cone of the aircraft was designed so that the pilots have a 15-degree view down angle. Note that the instruments and flight controls were not modeled.

Landing Gears and Tires

The placement of the main landing gear was carefully designed to make sure the aircraft is stable while loading, easy to rotate, and able to retract into the reserved space. The tires are selected based on the calculated weight and the Goodyear Tire Data Book.

Airfoil Selection

To meet the cruise Mach number requirement, supercritical airfoils are selected. The simulation data is verified with documented experimental data, and the drag divergence Mach number (MDD) of selected airfoils are interpolated from curve-fitted data recorded in NASA Technical Paper TP-2969. The geometric twist of the wing is designed to match the foils selected so that they work at their designed operating point.

Wing Design

The main wing thickness is mainly determined by the required volume of wing tanks, also considered the bending moment it would resist. Geometric and aerodynamic twists were added to avoid tip stalls and to achieve elliptical wing loading. More details on airfoil selection and wing design can be found in Design Note 2 below.

Tail Design

The main load path of the stabilizers was determined before the control surface sizing was finished, due to the demand for the trimmable horizontal stabilizer. The pivot point of the horizontal stabilizer is located at its aerodynamic center to minimize the load on the actuator. The pivot point restricted the location of the rare spar.

Integration

The sub-assemblies were integrated for the submission, and more details are added. Pitot tubs and antennas are added based on educated guess only to add more details to the final model. The new logo and livery were designed for rendering.

Documents

The concept selection document includes the 3D models I made to represent the concepts of the group members' hand drawings.

The design notes and the design review files are the team's work, it could not be done without the effort of the other teammates. Their work and responsibilities are specified at the beginning of the documents.

Please also check out page 31 of the General Aviation Aircraft Design: Applied Methods and Procedures by Dr. Snorri Gudmundsson, for the full cutaway picture of my 3D model.

Team1Concept.pdf

Initial Concepts

Team1 DN001.pdf

Design Note 1

DN-002-Team1.pdf

Design Note 2

Album.pdf

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