MAE461/462 Mechanical Design Capstone Project
Flight day images: 10 May 2007
- The class poses with the craft (the skirt is deflated).
Pictured are (left to right):
Luke Scruby, Evan Van Ness, Trevor Wesolowski, Mike Jones, Ryan O'Grady, Eric Zettervall,
Dave Adelman, Arthur Orton, Marc Heisel, Mike Coleman, Will Goodrum, Louis Steva (lab technician),
Josh Heim. Kneeling: Eric Maslen (course coordinator).
Not pictured: Jon Kassoff, Brady Bolton,
Mark Hopke, James Clarke, Johan Yavari, Drew Michelotti, Matt Federici, Nate Grady, and Alex Sohn.
- The final design was known to have the center of mass aft of the center of pressure.
The consequences of this offset were not clear but produced excessive skirt drag during
testing. Adding 50 pounds of ballast at the bow gave a nearly perfect balance:
- Thrust was provided by a three-bladed fan in a duct, driven by a 25 HP
two stroke Rotax 277 engine. Vectoring was accomplished by a pair of rudders. Note
that they are not air-foils. Extensive CFD analysis suggested that flat plate rudders
work better at high angles of attack and produced more ultimate lateral force than
could be gotten with foil rudders.
- We had some problems with the ignition kill on flight day, requiring
a bit of field repair. The ignition kill switch was momentary, normally closed
and vibration caused the contacts to bounce open, killing both engines. The fix
was to "borrow" a toggle switch that turned out to be redundant.
- The lift engine oil should be checked before starting:
- Marc Heisel was the second pilot, after Will Goodrum. This is early on the pilot learning curve.
- Luke Scruby is planning to be a Navy Seal so flying a hovercraft is
part of his career plan. He proved to be a pretty good pilot:
- However, even for Luke, without a thrust reverser, it can be hard to extricate the craft
after a bad navigational decision. The obviously shredded outer skin
of the thrust duct is cosmetic and was the product of an earlier mishap.
- Arthur Orton worked with Jon Kassoff on rudder analysis, design and construction so
Arthur had a particular interest in steering performance. Check out the big grin in the second photo.
- Josh Heim managed weight and balance of the design. As luck would have it, he was also the lightest
student in the class and this gave him at least some advantage flying. You can see in the first photo that,
with ballast at the bow, the craft is nearly perfectly balanced (compare skirt shape at the bow and stern).
- Mark Hopke gets the award for the most careful piloting, bringing control of the
hovercraft to a level not managed by anyone else. Mark is meticulous and it paid off here.
- In the fourth of these photos, Evan Van Ness demonstrates a persistent problem with the craft:
hard right turns make the craft pitch down at the left rear corner. This runs up the drag
at the left rear corner dramatically making the right turn difficult (the drag tends to cause the craft
to turn left, counteracting the rudder moment).