This is the main page for the aeronautics unit, created by Mark and Logan. The progress on our first plane is shown below, while this a link to our second plane--our semester project.



Here is our page tracking the progress of the construction of the airplane. Updates are given in chronological order, and are written every time significant progress is made. Pictures are provided, though not always reliably up-to-date, so you can see what we're doing for yourself. We try our best to explain the reasoning behind each design characteristic as well, because there's a reason for everything. While some design aspects are rather superficial, such as the paint scheme, most of them are based off of the physics of aerodynamics that we have researched or already knew of. After all, it's a learning experience.


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Shown left is the schematic for our current project, a custom sport/park flier. A sport flier
is an airplane that is designed to be capable of advanced aerobatics and maneuverability.
"Park flier" is a term used by modelers, simply meaning that the plane is designed to be
flown in parks, as opposed to large flying fields. The main construction will be out of
polystyrene foam insulation, which will be carved out of a massive 4' by 8' by 2" sheet that
we bought at Lowes (http://www.lowes.com/) for about 30 bucks. After the construction of
the body is complete , we will add 4 servos and a motor for radio control.

Shown below is the rough cut of our wing which, as the design indicates will measure just about
40" long.

As of now, this wing has been completed. We don't have pictures of it currently, but the wing
measures 40" by 10" by 2". The design involves a flat-bottom airfoil (the shape of the wing when
viewed from the side), which is typical of full-sized airplanes and provides maximum lift. Using
a flat bottom while also maintaining a curved top allows for maximum difference between the
speeds of the air traveling over the wing and the air traveling under it. Because faster moving air
exerts less pressure pressure than slower moving air, this design also creates a maximum
difference between air pressures above and bellow the wing, in turn creating maximum lift. Sports
fliers sometimes utilize semi-symmetrical airfoils, however. Because the top and bottom of the
wings are less distinctive from one another, these provide less lift, but provide improved
inverted flying (flying upside down) characteristics. We decided that flying right-side up is more
important, so we stuck with flat-bottom. Ailerons (the rectangles on each side of the trailing edge
of the wing) are what allow the plane to roll, and with sport flying in mind, we designed long and
thin ailerons for this plane, commonly known as strip ailerons. These give the airplane a very
predictable and smooth roll pattern. Next is the fuselage, or the body of the plane.
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Here is the wing with what we have of the fuselage. The wing is completely constructed, with the
airfoil and control surfaces in place. The servos, the tiny motors that move the control
surfaces, lie underneath the black tape, and their wires lead to the fuselage, which can
be seen in its rough shape. The foam shavings all over the floor show how messy the process is.


We were regretfully unable to get together and complete construction this past weekend, so instead of a project update I will make a brief post on the basics Aeronautics as subject in general instead. For an aircraft to fly, there must be a force called lift. There are multiple types of lift, such as static, or dynamic lift (as in an airfoil). Now, there are two major methods used to achieve lift on an aircraft, known as aerostats and aerodynes. Aerostats achieve lift because they are lighter than air and will have inherent lift. The second type, aerodynes, achieve lift by pushing gas downwards (or towards the planet if you insist.) This action of pushing air downwards, by Newtons laws, naturally moves the aircraft upwards.


As of February 28, the body work on the plane is nearly completely finished. The nose has been shaped, the canopy has been built, the fuselage has been rounded, and the tail has been shaped. As far as the body, the construction of the control surfaces, or the flaps that move, on the tail are all that's left. After the body, installing the electronics and paint will be the only tasks reamaining. The servos in the main wing have already been mounted, but the ones in the tail have not, nor the main motor, battery, receiver, or speed control. Although that seems like a long list, the most time consuming tasks are passed. The shaping of the body posed some challenges. The center of balance plays a large role in flight. If it's too far towards the tail, the tail will droop while flying, increasing drag and slowing air speed. If it's too far towards the nose, the plane will tend to nose dive, and lift will be lost. Ideally, the center of balance should be between the center of the main wing and the point where the airfoil is at its highest, or about a third of the way behind the leading edge of the main wing. Measuring the curves for cutting is tricky business, yet essential to get right, because symmetry is key for aerodynamics. Getting a smooth surface from insulation foam was also difficult, because the material has a tendency to crumble instead of cut neatly. The foam also loses much of its rigidity when it's cut in thin sheets. Because of this, we decided to leave the elevator and rudder a full half inch thick instead of the planned quarter inch. We also reduced the width of the elevator by an inch on either side, because we learned from looking at real planes that we had designed the tail proportionally too large for the scale of the plane. However, everything else has been according to our plan that is shown at the top of the page. We, again, don't have a picture of the plane in its current state, but it looks like the drawing. We plan to have pictures soon.


March 5: The body work is even closer to completion than before, and the electronics are coming along. The servos to control the tail have been mounted and are functional. The rudder is completed, but the elevator has not yet been constructed. For foam work, that and the mounting of the motor still remain. The electronics are assembled, but not installed. In other words, the motor and all servos are connected and in working order, but the receiver, speed control, etc, have not been mounted into their final locations. Unlike the body of the plane, the electronics are not custom. We scraped them from another older model airplane, and they have worked out for us very well. However, the parts were taken from a slow flier, and since we want a sport flier, this was no good. The only part that we scraped that is significantly different for sport flying and slow flying is the propeller. For slow fliers, the propeller has a shallow attack angle and has a very curvy, elliptical shape, giving it a relatively small surface area. Sports flier propellers have a more aggressive attack angle and a rather flat shape, which allows for more surface area. A steeper attack angle and a larger surface area both contribute to the propeller moving more air per rotation, translating into higher speed. With this in mind, we decided to purchase a sport propeller. However, we have encountered another problem. We realized that typical acrylic or enamel spray paints will not be appropriate for the plane, because they essentially melt foam. Although paint seems like a rather superficial element, it is actually very important, both to act as a sort of sealant for the foam and to make the plane easier to see while in flight. We're discussing a way around this, and have thought of possible solutions such as airbrushing, using water-based paint, or possibly even using tape. Again, we plan to have pictures soon. Sorry for the wait. It looks like the drawing anyway.


Note: Although we originally planned to have each plane done in four weeks, this number was just a shot in the dark. We have realized that there is much more time involved in construction than we thought there would be, so it has ended up taking much longer than that. The weather has also been stubbornly cold, so we are waiting for some warmer temperatures until flying will really be practical. The electronics don't work as well in the cold, and foam has a reputation for being very brittle, which is no good. Since the semester is almost half way over, and only two planes seemed to be a disappointing number, Logan and I have decided to build seperate planes for the second half of the semester, bringing the total to three. We don't plan to make it a competition, because we will be designing planes with different characteristics, but we'll see.

March 16: It seems that we've been saying it forever, but we're even closer to completion now. Since the last update, the tail has been completed, and now all of the control surfaces (elevator, rudder, ailerons) are fully functional. Not only are the built, but the trim and throws have been set to how we want them. Trim refers to adjusting the neutral position of the control surfaces, which is important, because if it isn't properly adjusted, the plane wouldn't fly straight when it's supposed to. Of course, we'll have to adjust this futher after a test flight, but preliminary setting is helpful. Throw describes how far the contorl surfaces are able to travel. Not enough throw will prevent the plane from manuevering sufficiently, while too much throw will encourage the plane to stall, which would lead to a loss of control. As far as work on the motor, the propeller and the prop saver have been the latest progress. The prop saver (prop is short for propeller) allows the propeller to seperate from the drive shaft during landing. Otherwise, since our plane doesn't have landing gear, the propeller would likely brake on landing. If everything works according to plan from here, we will have the plane completed and flown by the end of Spring break.


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Here, finally, are the pictures we've promised. Everything is built--paint is the only thing missing.

The real purpose of this project is not to build a model airplane, but to test different aerodynamic design aspects. Once the plane is ready for flight, we will record its performance in a number of ways. We will test roll and loop speed, which will tell us how agile it is in flight, we'll test the turning radius and loop height to determine manueverability, we'll approximate top speed, minimum speed, and flight time to measure the power efficiency, and we'll also observe qualitative characteristics such as stability and resiliance to wind.

March 28: The plane works!!!! The first test flight was successful. The basic capablities of the plane were tested, such as turning and roll ability and speed. Because of strong winds, official records would not have been reliable, so we didn't make any quantitative observations. However, we'll take the fact that it flies at all as a victory at this point. Now we just have to wait for a nice day and some free time, then we can take records. Also, the plane is actually not very difficult to see, so paint might not be necessary. Remembering what paint can do to foam, not painting it is something of a relief. Based off of what we've learned in construction and from the observations that we will make about flight, we will begin to organize our ideas on our next planes soon.

April 8: So, on the day of the in-class flight, the rubber band on the propeller broke. Of all the problems that we thought would come up, this was rather unexpected. The good news is that the plane will fly again, and that the day served as a proof of concept. We're not planning to have another class presentation, because of its impracticality, but the best idea seems to be to record a video of its flight on our own time, and then post the video on this wiki.