Edison Aerospace continues to make progress in aircraft design on the road to releasing a type-certified remotely and autonomously controlled full-scale airplane for agricultural aerial application.

Edison Aerospace aircraft
<em>A full parametric model is created in OpenVSP<em>

One of the aspects of the R&D process that is critical to the design of an aircraft is to get computationally predicted values for lift, drag, and stability that are more precise than those used to size the aircraft.

Edison Aerospace aircraft
<em>The OpenVSP parametric model is simplified by excluding the fuselage<em>

There are two ways to do this sort of analysis of an original design. The first involves making a small-scale model and placing it in the wind tunnel to collect empirical readings. This is a very time and labor-intensive practice that is not conducive to iterative design – to trying different configurations rapidly to find the best combination of features and performance.

The other method is to use a computer program to generate a mathematical model of the aircraft and get the same values quickly, allowing the designer to try many more combinations of features.

Edison Aerospace aircraft
<em>Original rendering of the Edison Heavy1 agricultural spray aircraft<em>

Edison Aerospace is using the OpenVSP (Open Vehicle Sketch Pad) software package originally created by NASA to perform basic aerodynamic calculations on a parametric model of the subject aircraft.  A quick analysis will return the distribution of pressures on the airframe, coefficients of lift and drag, the distribution of lift along an airfoil, and how these parameters are affected by differing the angle of attack.

Edison Aerospace
<em>Cl vs CCREF computation for airfoil arrangement above<em>

Among the reasons for doing this computational work is to be able to confirm the sizing estimates made about specific airfoil selected (NACA 4412 for main wing and spray boom and NACA 0010 for the tail surfaces) and to be able to estimate the load distribution across the wingspan.

Another benefit of the OpenVSP package is its ability to plot trailing wakes beyond airfoil features to visualize the aerodynamic interaction of various components.

Edison Aerospace
<em>Pressures acting on components at an angle of attack of 10 degrees and trailing wakes<em>

Software such as OpenVSP is an immensely valuable tool during the R&D process that reduces the iterations that will have to be made in the physical space but building models, testing them in flight or in the wind tunnel, then revising the design and repeating the process. We continue to refine our test model and conduct flight system testing to program this component for quick installation into our experimental prototypes.

<em>Adding multiple propeller discs to the model tip vortices can be observed on winglets<em>

Once a model is built, more details can be added to it to make it as realistic as time and effort permits. Here we added the multi-engine propulsion system of the Heavy1 experimental prototype to see the effects of each change. If we change the model by replacing the propeller discs with blades and moving the outer props to the wingtips, changing the rotation direction to offset the tip vortices (rotating toward the outside), the model looks a little better.

Edison Aerospace
<em>Moving outer props to the tips and changing spin direction to counter vortices yields a better flow model<em>

In contrast, without changing the spin direction to counter the wingtip vortices would yield a model that is closer to today’s existing single-engine aircraft that have large vortices shed by the wingtips. We can easily see the positive effect of using propeller spin direction to counter wingtip vortices. Adding the bidirectional winglets further aids our design to operate more efficiently and to utilize a wider boom, going beyond 75% of the span. Our testing will evaluate booms going out to 150% of the span to confirm our predictions based on the computer simulations.

Edison Aerospace
<em>Allowing wingtip propellers to rotate to the inside exacerbates the tip vortices and gives a better illustration of their behavior<em>

The next step will be the creation of a scale model of this exact airframe configuration for flight testing in a 2meter span model!