Monthly Archives: April 2014

Wichitalking ’bout Willis?

My sincerest apologies for the terrible pun. They will only get worse as the weekend progresses. We have arrived! The weather was excellent for flying both legs of the journey, and we have confirmed that our plane arrived to Wichita intact. This is crucial, because having a plane is integral to participating in an airplane competition.*

*Citation needed.

We experienced some minor turbulence en route, and in keeping with our new educational theme, I would like to explain that phenomenon.

Turbulent wake.
Turbulent wake.

In general, turbulent flow is the motion of a fluid (air, water, or whatever) that is chaotic and unpredictable. Pressure and velocity are highly variable within turbulent areas. Turbulence is, to simplify things, caused when the oncoming flow is moving fast enough that it scatters and disperses from its original, laminar pattern.

Not everyone knows it, but the external flow around airplanes is actually already turbulent! Laminar flow is “tripped” into turbulence by the plane slicing through the air. This is actually a good thing, because turbulent flow “tumbles” along the wing for a greater distance before separating. Picture a large semi truck, and the lull of air behind it. There is a high pressure in the front of the truck (oncoming air) but very low pressure directly behind it, because all of the air has been forced out of the way. For an airplane, the boundary layer separating from the wing can be a major source of drag. Minimizing this pressure drag effect is important, and so turbulent flow is useful for planes, cars, and so on. This is good, because at high speeds and for large objects, turbulence is unavoidable!

Designers will even go out of their way to induce turbulence! Golf balls are a clear example. A smooth sphere the size of a golf ball, hit by a human golfer, will not cause turbulent flow and hence the boundary layer will slip off quite early. (Clark Kent might be able to induce turbulent flow with a golf swing, but he can also fly backwards around the Earth to turn back time if he wants.) A rougher surface, like a golf ball with dimples, induces turbulent flow and a boundary layer that does not separate as early, greatly reducing pressure drag.

Texas Hold ‘Em

More accurately, Texas Hold Us. We have arived in Dallas and are awaiting our transfer to Wichita. Updates soon to follow. For now, some shameless rumor mongering about next year.

Currently, we focus on design meeetings (once a week) and build time. We would like to add more theory to our lineup. This will entail computer aided design tutorials, case studies of famous or influential aircraft  and some fancypants aerodynamics math.

After the competition, we are going to have some meetings to work out our syllabus. Exciting! In the coming posts, I will try to add some educational value by talking more in depth about the parts we inevitably end up repairing.

AIAA Weekly Update #8: Pretty Fly

flight2
The majestic model airplane, in its natural habitat.

IT’S ALIVE! After finishing with our indoor testing last week, we absconded to the park with our plane for some aerial amusement. Our maiden voyage was successful, with the plane taking off in good weather and zipping to and fro like it was made to fly. Probably because it was.

The results were certainly encouraging. We know that the plane can carry the necessary cargo, taxii across a rough surface, take off within the necessary distance, and even land without breaking (much)!

The plane has since been shipped to Wichita, Kansas for the competition! Our team will board a much larger plane to follow it there, on Thursday afternoon! The competition will take place from Friday to Sunday.

Expect to be spammed with blog updates in the near future! Also watch our twitter feed, which will be all atwitter with tweets this tweekend.

AIAA Weekly Update #7: Fin!

test2The plane is completed! One of the latest challenges we faced was manipulating the control surfaces. Our flaperons needed to have the ability to act as flaps and ailerons, using only one control stick! Ultimately we found a way to switch the mode between flap and aileron control, on the radio transmitter. Our tail/rudder assembly is also complete!

We are now testing the plane’s capabilities, making spare parts, and preparing for our competition journey! One of our first tests was a dry run of the corrugated sheet taxi mission. The plane must roll along a rough surface without taking off and while avoiding obstacles.

As always, if you are interested in building airplanes and airplane-building-related activities, stop by our weekly meetings on Mondays at 9 PM in 233 Mudd. Also head to the machine shop on the second floor of Mudd on Friday afternoons; we spend most of our build time there.

test4