Initial talks about this project began in the spring semester of 2022 at Mississippi State University, and it evolved into a full project over the summer break. Upon returning to school in the fall, the team decided that they were passionate enough about the end goal to pitch the idea to our advisors.

After researching several various winglet configurations, the team decided on using a simple but effective blended winglet is the best choice for our goals. The winglet is being designed using Solidworks CAD software. 

This design is in the process of being further optimized using MATLAB. The winglet's geometric parameters such as the cant angle, the angle of twist, and the winglet's span can be altered to increase the positive effect on the aircraft's performance. 

A MATLAB code will be used to find the stability and control derivatives using the optimized winglet characteristics. This is to ensure that the installation of the winglet will not have a substantially negative effect on the maneuverability of the aircraft. 

The Lift/Drag coefficients will be found using a MATLAB code created by the team. The purpose of this is to use these coefficients in finding the range and endurance of the aircraft with and without winglets.

The plan forward is to use the optimized winglet in the Computation Fluid Dynamics software ANSYS Fluent. From these results, the team can analyze whether the winglet increases the range and endurance of the aircraft and the effects on the controllability of the aircraft. If the results are sufficient, the team will move onto the flight-test phase of the project in the Spring semester.

View of the aircraft's wing dihedral

After continuing to research several various winglet configurations and specifications , the team decided on using a somewhat pointed, blended winglet for the Midget Mustang. The winglet has been designed using SOLIDWORKS CAD software. 

After trying numerous approaches to aerodynamically optimize the winglet, the team found the task to be too computationally advanced for our skill level, so a more scoped approach was adopted. The team continued to read various applicable literature, and decided on an initial winglet with the following specifications. The winglet as it stands has a cant angle of 45-degrees, a sweep angle of 30-degrees, and a twist angle of 5-degrees at the tip of the winglet. 

MATLAB code has been used to find the stability and control derivatives for both the unmodified airframe, and the airframe after modification with the winglets.

Computational Fluid Dynamics software ANSYS Fluent has been heavily utilized to gather higher fidelity aerodynamic information of the airfoils. From these results, the team has analyzed the scale of the winglet effects on the aircraft. This section of the project has been the most time intensive, requiring many alterations to the approach, and using a large amount of computational hardware and time.

The winglet with specifications of a cant angle of 45-degrees, a sweep angle of 30-degrees, and a twist angle of 5-degrees at the tip of the winglet, was evaluated within ANSYS Fluent. The winglet was showed a marked increase in lift to drag ratio over the three angles of attack that were investigated. The angle of attack that correlates closest to cruise conditions, 2.5° AOA, showed an increase of 9.57%.

Because the range of a propeller driven aircraft is directly proportional to L/D, the range of the Midget Mustang also increased by 9.57%. Endurance is not directly proportional to L/D, however it did show an increase of 3.06%.

Due to the increase mass of the winglets at the end of the wings increasing the moment of inertia, the roll rate about the longitudinal axis would inherently decrease. It was the owner's requirement that it not decrease by more than 50% of the current rate. By calculating the stability and control derivatives, it was found that the winglets would only decrease the roll rate by 11.21%, well within the limit set forth by the customer.

While the team initially hoped to conduct a manned flight test in support of the project, maintenance issues with the aircraft arose and did not let this occur. The team is satisfied with the analytical results achieved, the experience gained with real-life engineering style contracts, and finally the future of this project.

The project has a promising future for follow on work. Multiple current undergraduate students in aerospace engineering at Mississippi State have expressed an interest in continuing the research and experimentation for this project. This includes future project work and goals such as finite element analysis (FEA), internal structure design of the winglet, aerodynamic evaluation at other flight regimes, and finally an experimental flight test. 

The project team members referenced countless pieces of literature in support of this project, including speaking to many people about techniques and ways forward at road blocks in the analysis. Listed below is the key literature on which the team based the methodology of this project:

• An investigation on winglet design with limited computational cost, using an efficient optimization method

  • Masoud Heidari Soreshjani, Alireza Jahangirian 

• CFD Study of the Impact of Variable Cant Angle Winglets on Total Drag Reduction

  •  Joel Guerrero, Marco Sanguineti and Kevin Wittkowski 

• Winglet multi-objective shape optimization

  • Ali Elham, and Michel J.L. van Tooren 

• DIFFERENT TYPES OF WINGLETS AND THEIR CORRESPONDING VORTICES

  •  Anshuman Mehta 

• Aircraft Winglet Design 

  • Hanlin Gongzhang and Eric Axtelius 

• Effect of winglets induced tip vortex structure on the performance of subsonic wings

  • Gautham Narayan, Bibin John 

• Design of Winglet Device for Aircraft

  • Khamis Ali Al Sidairi and G. R. Rameshkumar