eVTOL Transition Analysis and Aerodynamics

A recent Stallion 3D study examined the NASA RAVEN-SWFT OpenVSP model as a 1,000-pound aircraft transitioning in forward flight while retaining its six vertical rotors.

The preliminary cases covered 7, 20, 40, and 60 m/s. Stallion 3D calculated aircraft lift, drag, moments, individual rotor power, total rotor power, and the aerodynamic power required to overcome drag. The resulting tables provide a simple baseline for transition as a hexacopter.

What the Initial Sweep Shows

At low speed, most of the required power is associated with the lifting rotors. As speed increases, rotor power decreases while drag multiplied by speed increases rapidly. Several rotors also begin to autorotate in edgewise flow. This indicates that a practical transition schedule must include rotor unloading, tilt, shutdown, braking, feathering, or another method of controlling the rotor state.

The all-vertical case is not presented as the optimum solution. It is a minimum-viable baseline. The next step is to vary proprotor angle, rotor grouping, aircraft attitude, and shutdown strategy. A small number of CFD cases can first identify the useful region of the design space. More expensive cloud or high-performance computing can then be applied to optimize the promising configurations rather than search blindly.

This is the gap Stallion 3D is intended to fill: establish a credible aerodynamic and propulsion plant model early, use real forces and moments to remove poor transition concepts, and reserve large computing budgets for the designs that justify further study.

View the Tables and Transition Graph

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Buy One Moth Trial

A one-month Stallion 3D trial is available for $299. The trial is intended for engineers who have a specific aircraft, UAV, eVTOL, rocket, or aerodynamic design that they want to evaluate using their own STL geometry.

The objective is modest: import the geometry, establish one or more useful CFD cases, review the forces and moments, and determine whether a larger analysis or optimization effort is justified.

Buy One-Month Trial on PayPal ($299)

Hanley Innovations
Stallion 3D Aerodynamics Software
www.hanleyinnovations.com

Soccer Skills: The Aerodynamics of a Bending Soccer Field Goal

Aerodynamics of a Soccer Ball Transcript

Welcome to Bend It Like Stallion 3D. The aerodynamics of a spinning soccer ball.

The colored surface represents the local flow speed around the ball, while the streamlines show how rotation changes the wake behind the ball. Because the ball is spinning, the air flow becomes asymmetric, producing a pressure difference across the surface. This pressure difference generates a lateral force that curves the trajectory during flight.

In this example, we examine the aerodynamics of a regulation soccer ball traveling at 67 mph. The ball is spinning at 600 revolutions per minute or 10 hertz to produce a side force across the soccer pitch.

The purpose of the simulation is to predict the Magnus effect and figure out the magnitude responsible for a bending free kick.

• To start the simulation in Stallion, we import the STL file of the ball.
• Next, we set the speed, flight angle, and sea level conditions.
• Then, we set the rate of rotation to 10 herz and the normal vector to the desired spin direction.
• Finally, we click the menu to generate the grid and solve the flow.

For this case, Stallion 3D predicted approximately 5.8 Newtons of drag and 5.7 Newtons of side force. These values are consistent with the expected aerodynamic behavior of a spinning soccer ball and demonstrate the software's ability to capture rotational flow effects.

Surface pressures, force components, and aerodynamic moments are computed directly from the Navier Stokes solution. Although this example features a soccer ball, the same numerical methods are used to analyze aircraft, UAVs, rockets, and EV2L vehicles, and of course, a real football as well 😀  By changing the geometry and the operating conditions, Stallion 3D can predict the aerodynamic forces and moments required for engineering design and stability analysis.

Please visit https://www.hanleyinnovations.com to learn more about Stallion 3D

Bend it like Stallion 3D. FIFA Inspired Aerodynamics Simulation ⚽🥅

 

A soccer ball was simulated in Stallion 3D at 67 mph (30 m/s) with 600 rpm (10 Hz) of spin to examine the Magnus effect responsible for a bending free kick.

The  Stallion 3D simulation predicted the following forces:
• Side Force: 5.72 N (1.29 lb)
• Total Drag: 5.70 N (1.28 lb)
• Lift: −0.333 N

The streamlines, in the attached side-view picture, show the wake generated by the spinning ball, producing the lateral force that curves the trajectory.  Although simple in appearance, predicting this behavior requires resolving the interaction between boundary-layer separation, rotation, and wake development around the ball.  Similar dynamic inputs into Stallion 3D are often used to accurately compute dynamic and damping derivatives for airplane, UAVs and eVTOLS stability and control. 

Sometimes CFD predicts an aircraft. Sometimes it predicts a free kick.

Learn more ➡️ https://www.hanleyinnovations.com

eVTOL Aerodynamics: Use Stallion 3D for Early eVTOL Concept Analysis. Compute lift, drag, moments and ideal power

This is a Stallion 3D near-hover simulation of the NASA RAVEN SWFT, a 1,000 lb eVTOL concept, at 7 m/s forward speed. The model includes six lifting rotors with pressure plotted on the aircraft surfaces and actuator disks. The pressure scale shown is approximately 100,950 to 101,450 Pa.

The computed surface forces are: lift = -86.31 N (-19.40 lbs), side force = -3.08 N (-0.693 lbs), pressure drag = 57.65 N (12.96 lbs), friction drag = 4.65 N (1.04 lbs), and total drag = 62.30 N (14.01 lbs). The related force components are FX = 57.65 N, FY = -3.08 N, and FZ = -86.31 N. The moments about the reference CG are pitch = 175.38 N-m, roll = -1.23 N-m, and yaw = -9.74 N-m.

The ideal rotor power from the six disks is 7,059.38 W, 7,065.66 W, 6,310.21 W, 6,314.22 W, 10,189.09 W, and 10,231.14 W, for a total ideal power of 47,169.70 W. This is a simple near-hover CFD check, but it shows the type of integrated aircraft, rotor, pressure, force, moment, and power information that can be reviewed directly inside Stallion 3D.

Performing early 3D aerodynamics analysis using accurate and accessible software ensures stable first flights. 

Please use the link be low to learn more about Stallion 3D.

➡️ https://www.hanleyinnovations.com 

Learn the Background Story about my CFD and Aerodynamic Software Business

 

I recently had the chance to talk with Roopinder at ENGtechnica on YouTube about aerodynamics, CFD, and some of the practical work behind Hanley Innovations.

The discussion is a good plain-English overview of how I think about simulation, aircraft design, and engineering software. It is a technical conversation about real aerodynamics, useful calculations, and the role of CFD in understanding what an aircraft actually sees.

Please let me know if you have any questions. 

To learn more about Hanley Innovations please visit https://www.hanleyinnovations.com.

Best regards,

Patrick.

Breaking the Sound Barrier: Shock Waves, Drag Rise, and the Physics of Transonic Flight

Why is it so difficult for aircraft to fly near Mach 1?

In this short video, I use Stallion 3D to look at transonic flow around an aircraft. The example starts with the Bell X-1, the first aircraft to break the sound barrier in 1947. The main idea is simple: as an aircraft approaches the speed of sound, the airflow does not change smoothly. The drag can rise sharply.

This speed range is called the transonic regime. In transonic flow, part of the air around the aircraft can still be subsonic, while another part has already become supersonic. This can happen directly on the surface of the aircraft. That is what makes the problem important for aircraft design.

When shocks form on the aircraft surface, the pressure distribution changes quickly. The forces on the airplane are found by adding up the pressure over the surface. If the pressure changes sharply before and after a shock, the aircraft can see a large increase in drag. This is one reason wave drag becomes important near the speed of sound.

The flow can also become unsteady. A shock wave may move back and forth on the aircraft surface. That motion can create unsteady aerodynamic forces. In some cases, those forces can contribute to structural vibration or other design problems.

One common way to reduce transonic drag is to sweep the wing. Wing sweep reduces the effective Mach number seen by the airfoil section and helps delay some of the strongest transonic effects. This is one of the reasons swept wings became common on fast aircraft. The video is a simple look at this problem using Stallion 3D CFD.

More information can be found at Hanley Innovations ➡️ https://www.hanleyinnovations.com 

Thanks for watching

Patrick 

Transonic Aircraft Design and Analysis

Transonic Accuracy with Stallion 3D

Transonic aircraft design is difficult because small changes in sweep, airfoil shape, angle of attack, and Mach number can produce large changes in pressure distribution and drag. Stallion 3D is designed to capture these effects with high-fidelity CFD, giving engineers a practical way to compare configurations before committing to expensive testing or redesign. In the example (see above picture), two similar wings with the same span, chord, aspect ratio, and area show very different drag results at Mach 0.85, demonstrating how sweep can strongly influence transonic performance.

This level of differentiation is important for CCA UAVs, small business jets, rockets, and other high-speed vehicles operating near or through the transonic regime. Stallion 3D can help identify how design choices affect shock behavior, pressure drag, skin friction drag, and aerodynamic loading. The goal is not just to create colorful flow images, but to produce useful aerodynamic forces, moments, and coefficients that guide design decisions.

The accuracy edge of high-fidelity CFD comes from resolving the physics well enough to separate meaningful design differences. For transonic aircraft, that means being able to evaluate sweep, airfoil selection, angle of attack, and geometry changes with confidence. Stallion 3D gives small teams and engineering groups a way to bring this type of analysis into early design trade studies, where better aerodynamic answers can reduce risk and improve the final vehicle.

Please visit the following link for more information about Stallion 3D:

➡️ https://www.hanleyinnovations.com

As always, feedback is welcome.  Thank you.

Best regards,

Patrick