Undergraduate thesis on propeller-wing/fuselage interference

[Demetrio Cucarella]

Hi Brandon,

My name is Demetrio Cucarella, and I am an undergraduate Aerospace Engineering student at the National University of La Plata (UNLP), Argentina, currently in the process of defining the topic for my final degree thesis (Trabajo Final de Grado).

I am reaching out to you specifically because your work on propeller-wing aerodynamics for the X-57 Maxwell program—including the high-lift propeller wind tunnel testing and model development—and your continued contributions to OpenVSP are closely aligned with the research direction I am considering for my thesis.

My thesis is required to include an experimental wind tunnel campaign, complemented by preliminary design and computational methods. The facilities and tools available to me are:

- A low-Reynolds-number wind tunnel capable of measuring complete aerodynamic loads (forces and moments) via a balance system, suited for 2D/3D models such as airfoils, wings, or small UAV configurations.
- A larger subsonic wind tunnel that accommodates full 3D bodies, with a Mach number limit of 0.15.
- Preliminary design tools such as OpenVSP, USAF Digital DATCOM, and similar low-order aerodynamic prediction methods.
- CFD capabilities (RANS-based solvers) to complement and extend the experimental and preliminary-design results.

Given these resources, I would like my thesis to address a problem that is genuinely relevant to current aeronautics research. I have been following some of NASA's recent low-speed aerodynamics work, such as the propeller-wing interaction testing of the tiltwing model in the 14x22-Foot Subsonic Tunnel for Advanced Air Mobility applications, and the RAVEN subscale eVTOL research aircraft program, and I believe my available facilities could be well suited to explore related questions at a smaller, academic scale.

My current thesis idea is to characterize propeller-wing and/or propeller-fuselage aerodynamic interference experimentally, and to evaluate how well potential-flow-based methods—specifically actuator disk and blade element momentum models, as implemented in OpenVSP/VSPAERO—are able to reproduce that interference. The goal is to identify the range of conditions (advance ratio, relative propeller-wing/fuselage position, angle of attack, and possibly tilt angle) over which the potential-flow approach remains reliable, and where it starts to break down compared to wind tunnel data and complementary CFD analysis.

That said, this is a working idea rather than a fixed plan, and I am genuinely open to other research directions you might consider a better fit for the facilities described above.

I would deeply appreciate any guidance on the following:

1. Are there open research questions or specific configurations within propeller-wing/fuselage interference work that would be worth investigating at an academic scale with the facilities described above?
2. Are there published reports, open datasets, validation geometries, or known regimes where actuator disk/BEM methods are known to lose fidelity that could help orient this study?
3. Are there other open problems in this space that might be a better fit for these facilities?
4. If there is a more appropriate point of contact, I would be grateful if you could redirect me.

I am only looking for publicly available research directions or open literature.

Thank you very much for your time.

Demetrio Cucarella
Undergraduate Aerospace Engineering Student
Universidad Nacional de La Plata (UNLP), Argentina

[Brandon Litherland]

Hi Demetrio,

There is a lot to discuss here and I don't have a great deal of time to respond but I wanted to make sure you knew I had seen your request.

Some quick resources that will indicate current research paths at NASA are:

NASA Urban Air Mobility Reference Vehicles: https://www.nasa.gov/reference/uam-refs/

NASA Open eVTOL RAVEN: https://www.nasa.gov/raven/

See also the NASA Validation Test Plan: https://www.nasa.gov/rvlt-validation-test-plan/

1. There are many open questions that still need study and verification or validation. 

    - Depending on what kind of application you're studying, whether VTOL, DEP STOL, or others, the kind of experiment you will run may change.

    - Part of the reason that there is little public test data for these configurations is that it's almost as hard to integrate subscale prop-wing hardware into a wind tunnel model as it is in aircraft. You would face the same challenges. I recommend keeping things relatively simple.

2. Actuator disks don't like to operate in edgewise flight like helicopters.  Solvers may have embedded corrections to account for this but not always.  Very low forward speed or pure hover can pose a challenge to disk methods. Comprehensive Analysis codes like CAMRAD and CHARM are tailor-made for these applications but have their own limitations and assumptions.  

3. The facilities you describe would be appropriate for a small-scale, isolated prop-wing effect study.  For example, a single wing section with a single propeller that you then change the propeller position and orientation to find blown-lift effects and rotor performance. However, to truly understand the results, you would need to properly isolate the rotor loads from the wing loads (two balances or load cell and balance).  The complexity of even this simple setup is non-trivial. See work by TU Delft and NASA for propeller placement effects on wings.

4. I can put you in touch with others if you feel you need more information after this.