Introduction: Ground Effect Vehicle Demonstration
A Ground effect vehicle is a special type of air frame built to take advantage of a unique phenomenon known as "ground effect" witch allows for increased lift and decreased drag when close to the ground
Note: this is a demonstration device supposed to show an often ignored principle. IT IS NOT AN RC PLANE
- 3 pieces of Balsa wood
- One polystyrene tray (Styrofoam plates could also work)
- glue (preferably wood glue and Elmer's glue)
Step 1: Preparing the Materials
I Cut two wings from the plate that were 7 inches long and 4 inches wide
I selected two balsa boards that were 10 inches long
Note: it is important that the face of the columns be rectangular (see the 4th above photo)
I Cut out two polystyrene boards to the dimensions of one of the balsa wood sticks
Step 2: Setting the Base
Using wood glue, attach the first balsa stick to the second one in a perpendicular fashion. Then wait for the glue to dry.
Note: things don't have to be exactly center-line, but the more centered is better
Using Elmer's glue, attach the two polystyrene sticks to the first balsa stick in the manner shown above. Wait for the glue to dry
Note: if the width of the second balsa wood board is great enough that it sticks out, then trim it
Measure the width of the above creation.Then cut a third polystyrene piece and glue it the top of the existing piece. (see picture 3)
Remember to wait for the glue to dry completely before moving on.
Step 3: Attaching the Wings
glue the first wing in such a fashion that the right angled vertex is the highest point on the triangle, and the hypotenuse rests completely against the ground.
Note: some masking tape may prove useful in holding the wing in position while the glue drives
After the glue on the first wing is dry, repeat the process for the second wing
Step 4: A Proper Tail
Cut out a rectangular gap from the top of the main body of the airframe.
insert another balsa wood board (approx. 4 inches) into the gap and glue it.
attach a length of polystyrene to the top to serve as a tail. Cutting a gap and sliding the wood through will make it easier to glue.
Note- a curved piece (such as the cusp of the polystyrene tray) will work best for our purposes
Step 5: The Finishing Touches
A tape to the edges of the wings to allow a better seal with the ground
Add tape to any structural weak points
Step 6: An Explanation of This Demonstration
Place the model on the ground and push it forward. If you do so forcefully enough, the vehicle will rise up, but then it will stall and fall back to the ground.
This is because the vehicle we just built doesn't have a good enough lift-to-drag ratio to fly normally, but it can lift off the ground because of the aforementioned "ground effect" principle, wherein increased lift results from air being pushed between the wings and the ground. This is different from normal flying conditions wherein the shape of the air foil results in changes in air-pressure that generate lift.
This is important to know for two reasons:
- Take-off requires an in-depth understanding of the ground effect to minimize instability
- Changes in lift and drag effect stall speed and can result in bouncy landings that could damage a model if one is not aware of, and prepared to compensate for, ground effect.
The sources for ground effect and flying are posted below, and I hope you will use what you learned from this demonstration to safely fly your own drones and model planes.
Source for how ground effect works https://www.flitetest.com/articles/ground-effect
Source for how normal fight works: https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-aerodynamics-58.html