Aerospace Capstone Design Projects Should not Stop at Slow

Years ago, I completed my bachelor's degree in aerospace engineering.  Back then, the fastest computers that I had ready access to was my Commodore 64 and of course my HP-4-CV. I used my C64 to work on a rocket staging assignment for in my senior year.  I wrote a partial differential solution (heat equation) for the CV.

NASA BWB Concept at v=290 m/s. Stl file from NASA OpenVSP.

Today, personal computers, laptops and even phones are extremely fast.  However, engineering student are forced to limit exciting design projects such as passenger jets and  futuristic supersonic transports to the conceptual design phase of subsonic flight.  The main reason for this is that current analysis tools such as CFD software can take too long for students to master over one or two semesters when faced with additional obligations such as non-engineering courses, part time jobs and other graduation requirements.

Aerospace engineering should be fun (because it is).  A quick and easy tool can help students design and analyze (on their own) race cars, jets, UAVs, and other vehicles.  It can help them to determine how delta wings of various shapes work at different angles of attack and even at supersonic speeds.

AR=2,  100 m/s at 25 deg. angle of attack (pressure).

AR=1, 100 m/s at 25 deg. angle of attack (pressure).

AR 2, 670 m/s, 25 deg angle of attack (pressure).

Over the last few years, we developed a few computer programs to help students get more out of their design projects.  The latest of these programs is Stallion 3D.

Even with time constraints, students can use their personal computers to take designs to the next speed. Using Stallion 3D, it only takes about one minute to setup a jet for analysis on a laptop computer.

The analysis can be completed (about 6 hours for 500K cells) while they use their computer for other assignments or get valuable sleep.

Stallion 3D works well with other tools available to the student (suchs as NASA's OpenVSP).   The following video shows how the two can work together.

The whole idea of Stallion 3D is to accelerate aerospace engineering education to any speed or at least to move as fast as a cow.

Cow in ground effect at M=1.6

Cow with store (M=1.6)

More information can be obtained from http://www.hanleyinnovations.com

For additional results, visit (Like) our Facebook page at https://www.facebook.com/hanleyinnovations.

Thanks for reading.

AIAA 51st Aerospace Sciences Meeting

I would like to thank everyone who visited Hanley Innovations' booth (321) at last week's 51st AIAA Aerospace Sciences Meeting in Grapevine, Texas.

We had a great time seeing old friends and meeting new ones as we discussed the latest innovations in aerospace engineering.

I would like to remind you that Stallion 3D is now a component of the Aerodynamics ClassPack.  The ClassPack is an excellent tool for aerospace engineering education for students studying basic aerodynamics as well as students working on senior year capstone design projects. More information about the Aerodynaics ClassPack can be found at:  http://www.hanleyinnovations.com/classpack.html

The following video shows how Stallion 3D can be used with NASA vehicle Sketch Pad software.

Do not hesitate to contact us at (352) 240-3658 if you have any questions about our software products.

Thanks for reading.

Flying Fast

One intriguing aspect a futuristic flying car is the promise of fast personal transportation. You will hover off your driveway and arrive at your destination hundreds of miles away within a few minutes. Lunch in New York and dinner in Los Angeles.

 To capitalize on this promise, the car must fly at a supersonic speeds. Supersonic flight involves shock waves (also called sonic booms) and this might not work so well for your neighbors. The following video shows a simulation of shock waves (generated using MultiElement Airfoils 5.0).

Shock waves/Sonic Boom Simulation

One way of reducing the effect of the sonic boom is to use the Busemann bi-plane concept. Of course, this arrangement of wings does not produce lift. However, they might be useful if integrated into the propulsion system or a cleverly designed shock wave deflectors for lifting surface.

 The figures below show MultiElement Airfoils calculations of the Busemann airfoil operating at on- and off-design conditions.

On-Design Analysis of Busemann bi-plane without external shock waves 

computed using MultiElement Airfoils.

Off-Design Analysis of Busemann bi-plane with external shock waves.

It is not too early to start your design of the next wave in personal transportation. Please visit http://www.hanleyinnovations.com/mefoil.html to find out more about our software for analyzing multi-element airfoils in subsonic, transonic and supersonic flows.

I look forward to your comments and questions.

Thanks for reading.   Patrick.

Why Your Next Airplane Design Will be Your Best

Why your next airplane design will be the best?  Aircraft design is an iterative process.  This is why Boeing, Airbus and even NASA need lots of scientists, engineers and mechanics to carry out the engineering process. Here's an exercise, fold a sheet of paper into a paper airplane and get it to fly to your satisfaction the very first time (how many times did it take?)

Because aircraft design is an iterative process, it becomes critical that every iteration or design step is efficient. In addition, each iteration in the design should advance the project in the right direction (this is called convergence ).  In the modern aerodynamics design, tools such as analytic methods,  computational fluid dynamics, wind tunnels, scaled models and flight testing are necessary to ensure a fast rate of convergence.

Why your next design will be the best?

1.  There are a number of airfoil analysis software currently available to help you to quickly and accurately analyze cross sectional shapes for wings, struts, rudders, landing gears, flaps and other components.  You can use  these tools to select shapes that provide good lift at the expense of low drag.  Another consideration (especially for wings) is the use of airfoils that produce high lift without huge destabilizing pitching moments (this reduces the tail drag).  Some airfoil tools are free (see Xfoil).  Other are efficient and accurate and help you to finish this crucial first iteration ahead of the pack (see, http://www.hanleyinnovations.com/vf50.html).

VisualFoil 5 can compare the performance of many airfoils on a single graph.

2.  Once you have cross sectional shapes, the next step is the skeleton airplane.  The skeleton airplane is essentially just wings, winglets, canards, flaps, tail and rudder.  The skeleton airplane should be a good enough approximation to the actual aircraft to help you to compute lift, drag, longitudinal and lateral stability, angle of trim, 3 DOF trajectories, component loading (for stress calculations) and drag reduction (winglets).

Getting the most out of the skeleton aircraft is key to the next step in the design process. Free tools such as AVL (Athena Vortex Lattice Method) allows you to analyze the skeleton aircraft using a horse-shoe vortex lattice approach.   If entering each component using a text file leaves you behind schedule, MultiSurface Aerodynamics (MSA) provides a modern user interface that expedites the design process (based on vortex rings method). MSA is the ideal tool to compute and identify form and induced drag from different wing components and design/position winglets, canards and the tail-plane (see http://www.hanleyinnovations.com/multisurface and http://pdf.aiaa.org/jaPreview/JA/2010/PVJA44453.pdf).

MultiSurface Aerodynamics can quickly perform loading & Stability Analysis

3.  As a design engineer your imagination and experience are your biggest assets. By this time in the process, you have formulated your ideas and analysis findings into a 3D solid model that resides in a CAD program (Rhino, Solid Works, Autodesk Inventor, NASA's Open Vehicle Sketch Pad openvsp.org).  This is the stage where efficiency is most critical because you must test the design as a unit. A good way to proceed is to use computational fluid dynamics or CFD methods. Traditional CFD methods requires that you construct a mesh for each design iteration that you wish to test.  This is often difficult and time consuming especially for 3D models (see http://www.symscape.com/blog/why-is-cfd-difficult).

The more parameters you can test, the better the design. If your next design is to be your best, you will benefit from Stallion 3D, a novel and accurate tool that eliminate the mesh generation process. This allows you to efficiently analyze and optimize your CAD models for this final step in the aerodynamics conceptual design process. The following video shows all the steps required to enter and analyze your aircraft design in Stallion 3D.
 

Stallion 3D can go from solid model to results in as little as 1.5 hours on a laptop computer.

More information about Stallion 3D can be found at http://www.hanleyinnovations.com/stallion3d.html.


Thanks for reading.

NASA's OpenVSP Hangar

NASA Open Vehicle Sketch Pad now has a hangar area with many 3-D models that you can use for inspiration and guides for your own original designs.  The url is: http://hangar.openvsp.org/.  The hangar currently lists 74 models for download.

 I used Stallion 3D to analyze some of the models in the hangar.  Simply export the model from  Open Vehicle Sketch Pad in the .stl format and Stallion 3D can read in and analyze the geometry.  The software can  model subsonic, transonic and supersonic external flow fields.  More information can be found at http://www.hanleyinnovations.com/stallion3d.html.
The following are some pictures from Stallion 3D.

Surface pressure on the surface of the F5 model at a speed of 290 m/s.

Velocity near the surface of the Q2-Model at V=100 mph.

Pseudo-Top-Gun Scene using the F15 for the F14 and the F5 standing in as the MIG. The airplanes were analyzed at a speed of 290 m/s.

Hypersonic waverider model at mach number of 6 (surface Mach number)

Surface pressure for the waverider model at M=6

More information about NASA's Open Vehicle Sketch Pad can be found at http://www.openvsp.org.
More information about Stallion 3D can be found at http://www.hanleyinnovations.com/stallion3d.html

Thanks for reading.

Ground effect experiment: Try this ...

Slide an old or unwanted CD across a desk, table or smooth floor. With the shiny side down (read/write side) the CD will slide a long distance in ground effect.  With the shiny side up, the CD will tend to stick to the surface.

Why?

The first thing to notice is that the label side of the CD is completely (well almost) smooth and flat.  While the read/write side has a notch (ring) near the center hole of the CD (where the plastic is transparent) on an otherwise smooth surface.

I performed a 2-D analysis of the CD airfoil (at the center-line) using Hanley Innovations' MultiElement Airfoils software package. The notch was set to a height of 0.0125 inches and the CD was placed 0.025 and 0.0375 inches off the ground.  The speed was set to 10 feet/sec and the Euler code was used to model the flow.

Grid generated automatically using MultiElement Airfoils.

The following is the results for the CD with the read/write side up (Cl = -0.105).  The bottom line represents the ground plane:

With the read/write side up.  The computed lift coefficient was -0.104 with h=0.025 in

Velocity distribution of flow near the notch (bottom line is the ground plane).

The negative lift coefficient or down-force caused the CD to stick to the surface.  It will make a great race-car in this mode.

Next, the flow, with the CD read/write side facing down, was computed in MultiElement Airfoils.  This time, the lift coefficient was +0.105

With the read/write side down, the lift coefficient was +0.105 with h=0.0375 inches.

Velocity distribution of the flow near the notch.

The positive lift coefficient caused the CD to lift free from the friction on the floor and provided a longer journey.  This disc models a WIG (wing in ground effect) or Ekranoplan in this mode.

These results suggest that the notch-ring near the center of the CD is the reason for the wing-in-ground effect behavior.  

Do your know of other simple ground effect experiment?

Thanks for reading and best wishes.

Patrick
http://www.hanleyinnovations.com

Five Reasons for 3D Aerodynamics

Are you in the process of designing a new aircraft, sailboat, or automobile.  3D analysis can play an important part in the design process.  Please consider 5 reasons (not necessarily definitive) to use 3-D aerodynamics early in your design process.

5.  Your design should not look like your analysis & design tool.  If you are too comfortable with 2-D analysis eventually your real-world designs will all resemble airfoil shapes.  A good 3-D design and analysis tool should render and analyze the exciting concepts that resides within your creative mind.  Feel free to throw caution to the wind and reap the rewards of your imagination.

Stallion 3D analysis of a human in the wind.

4.  An airplane is a 3-D object and is usually designed to be stable in flight.  Good stability in flight requires accurate computations of the location of the aircraft neutral point,  the size of the vertical tail (for lateral stability) and effects of the wing's dihedral angles.

Stallion 3D CFD Analyis of the SeaBee Aircraft from NASA VSP Hangar.

3.  Like humans, air prefers to use the "extra" third dimension to get out of the path of a speeding car.  If you wish to determine the down-force on a car wing in ground effect, two-dimensional analysis can provide much insight into the airfoil shape and angle of attack.  However, in 3D the air has a tendency to flow around wings of low aspect ratio that are too close to the ground.

MultiElement Airfoils analysis of a NACA 2412 wing in ground effect.

The figure below shows the same airfoil shape used on a wing of aspect ratio two.  The downforce on this wing will be smaller than its 2-D counterpart.  Use 3D aerodynamics to develop new and exciting methods to force the air through wings shapes that will capture the maximum downforce.

Stallion 3D analysis of Aspect Ratio 2 Wing in Ground Effect

2.  3D aerodynamics can be used to model the structure and planforms of wings that decrease drag (such as wing with winglets), increase downforce (end plates) or enhance the integrity of the structure (joined wings). 

ESwift Aircraft from VSP Hangar Analyzed in Stallion 3D.

1. Several year ago, 3D analysis was costly and difficult. Now, 3D aerodynamics is easy and cost effective.  My laptop computer is fast enough to analyze the 3-D Euler/Navier-Stokes equations (and so is yours).  Take advantage of modern CFD codes such as OpenFoam, Caedium, grid generation software such as Pointwise or  Stallion 3D for a complete aerodynamics conceptual analysis to enhance your creative process.

More information can be found at http://www.hanleyinnovations.com/stallion3d.html

How can you take advantage of 3-D analysis?

Thanks for reading.

References:Stallion 3D:  http://www.hanleyinnovations.com/stallion3d.html
Caedium: http://www.symscape.com/product/caedium
Pointwise: http://www.pointwise.com/
OpenFoam:  http://www.openfoam.com/