Direct Lift Control (DLC) of a Box-wing aircraft

Motivations

• Figure out how much benifits a box wing aircraft can acquire from DLC
• Learn how to design an aircraft(Including aerodynamic design and structure design processes)
• Learn how the aircraft can be controlled by flight control systems
• Get some usage experience on relative softwares
• Learn how to work as a team to solve a problem

Role&Responsibility

• Aerodynamic design of the box wing aircraft
• Structure design of the wings
• Deesign the control law of direct lift control and vallidate it through simulation
• Design the dirct lift Control experiments
• Analyze flight data and conclude the experiment.

Challenges & Proposed Solutions

Challenges: Knowledge Gap

While numerous challenges and difficulties ocurred during the projects, the most bothering one is the knowledge gap. The projects started when we were sophomores, as the curriculums relating to aircraft design would comming at next year, we could not expect to acquire relative knowledges from these courses or the project process will be delayed.

Proposed Solutions:

Learn and Ask!

We’ve decided to recruit a pupil who had experience in either design or building aircrts, and finally we invited Mei to be one of our teammates, Mei was also a sophomore at that time but he had joined our school’s model aircraft club, and was experienced in building model aircrafts. Mei was very enthusiastic and gave us many practical ideas on how to build a flyable aircrafts.

Besides, we decided to learn from books and thesis to see how to build an aircrafts. And ask for help from our project memtor.

Control Law:

A simple but effective control method was constructed as follows. Thanks to the test flight we were able to figure out the dynamic derivatives through system identification, and designed the control laws and simulate them in SIMULINKS. The aleron of fore wings and after wings were connected through a constant factor(i.e 0.7 in the following figure), and a PID algorithms were implemented to leave out the residuels and made aircraft stay level.

DLC benefit

As shown in the figure, DLC control do affect the climb rate of the aircraft, though the effect is subtle compared with the original trajectory.

Projects Outcome&Highlights

parameter identification: dynamic derivatives identification of after wing alerons boxwing in flight teams

Final thoughts

It was shown that the DFC for box wing aircraft has potential values for overload controls like gust alleviation, while it has limited capablity to change the trajectory of the aircraft as the control force will soon be cancelled out by the change of aircraft angle of attack.