User:1sfoerster/enes100/fall2014/Airplane float

Problem
First attempts had little design. The team built, tried, assumed too heavy, made lighter. No design, no measurement of weight, no computation and physical location of center of mass, no theory of flight, no testing of lift.

Fall 2014: Blimps are rare and extremely expensive. Need an affordable product that can be used for same purposes as a blimp and more. Can be used for constant surveillance for weather and/or traffic, military purposes, and for wireless internet services that hovers wherever you go.

Conceive
Fall 2014: Build an airplane that can successfully stay in the air for over 30 seconds and only be powered by a rubber band. Eligible to compete in the Free Flight competition.
 * Build an airplane to compete in a Free flight competition.
 * video of competition

Design
Actually design the airplane on a computer with drawing software using some established technique.

Test lift using the air handling system within a building big rigging a balance similar to the Wright brothers from the ceiling.

Fall 2014
The first design incorporated a flat wing made out of a wooden coffee stirrer frame and covered with plastic wrap, the propeller was also made out of wooden coffee stirrers and plastic wrap.

After Design Attempt 1, we decided that we should focus on making a working glider before putting efforts into the propeller.

No need to make a complicated Center of Gravity test. All that is needed is something to balance the plane on.
 * video showing center of gravity of model airplane
 * using fingers and friction

We created test protocols in Project 2 Week 1
 * 1) Find open area with no obstructions and minimal wind.
 * 2) Twist propeller in opposite direction of its natural spin 100 times to tighten rubber band.
 * 3) Hold plane 6 feet above ground in hands, making sure propeller doesn't start yet.
 * 4) Before throwing, let propeller start spinning.
 * 5) Throw plane by moving hand forward around 4".
 * 6) Use stopwatch to count how many seconds the plane stays in the air.
 * 7) Record other notes (nosedives, heavy tails, any propeller issues, etc.).
 * 8) Repeat test 5 times per model to make sure numbers are repeatable.

This test was revised during Project 2 Week 2 using more definite terms for "minimal wind" and the amount of time the propeller should spin before launch.


 * 1) Find open area, preferably inside where wind is not a factor.
 * 2) Twist propeller in opposite direction of its natural spin 100 times to tighten rubber band.
 * 3) Hold plane 6 feet above ground in hands, making sure propeller doesn't start yet.
 * 4) Before throwing, let propeller start spinning for 3 seconds.
 * 5) Throw plane by moving hand forward around 4".
 * 6) Use stopwatch to time how many seconds the plane stays in the air.
 * 7) Record other notes (nosedives, heavy tails, any propeller issues, etc.).
 * 8) Repeat test 5 times per model to make sure numbers are repeatable.

Lift is generated by the turning of a moving fluid. This involves curving the wing so the aft end of the wing points slightly downward, turning the air streams downward.

Implement
Build the airplane designed. Compute expected lift versus actual lift. Build wind tunnel if necessary. Build apparatus to measure lift. Compare measured versus computed center of gravity. Build apparatus to judge time, take pictures.

Supplier specializing in Free Flight kits using rubber instead of bands.

Choose to build airplanes individually and compete against one another or split up building parts of a single designed airplane, build separately, assembly together.

Used hair dryer to shrink plastic wrap.

Fall 2014
Brainstorm ideas, sketch designs, document everything, build design, build more designs, weigh all the models, narrow down and pick 1 for final presentation.

This Wikipedia page explains why a longer, higher aspect ratio (AR) wing can help gliders. Basically, a wing has the effect of a cylinder of air, with the diameter being the wingspan. If the wingspan is longer, with the same width, the amount of air the wing pushes downward is greater than with the shorter wingspan.

Materials needed:
 * Plastic wrap
 * Wooden coffee stirrers
 * Glue/adhesive (used Duco Cement)

The coffee stirrers are wooden sticks with a length of 6.875 inches and a width of 0.1875 inches.

Steps:
 * 1) Lay out plastic wrap over workspace.
 * 2) Take 2 coffee stirrers to act as the middle two sticks going long-ways and place adhesive on tips.
 * 3) Place the 4 coffee stirrers on each tip going long-ways.
 * 4) Cut 2 coffee stirrers in half.
 * 5) Glue 2 of the halves to the ends of the outer coffee stirrers to connect the lengths together.
 * 6) Take the wing lengths and mark at 1/4 of the length and 3/4 of the wing.
 * 7) Place the last two halves under the 1/4 mark and the 3/4 mark of the lengths. These act as ribs to make the wing more sturdy in crashes.
 * 8) Flip wing over.
 * 9) Wrap plastic wrap around the finished wing tight.

After noticing this, I placed a coiled spring on the front for weight. I used a pen cap as a temporary way to keep spring on.

Weight with coiled spring: 19.2g

Average flight: 1 second

Flight notes: Flew straight. No flips. Descended quickly though. Maybe too front-heavy, but better than stalling.

Though it flew longer with the heavier weight than without it, it was decided that the plane was way too heavy. Along with this, we determined that the flat shape of the wing was not producing enough lift for the velocity of the plane. Flat wing designs will not work. We considered other options for wing shapes, but it seems that the wing camber (shape) definitely needs to have a curve, with the aft end of the wing slightly curving downward.

Operate
Figure out the rules of a free flight competition. Create a mini competition and run it. Figure out the minimal competition that could be staged in 15 minutes or 2 hours for various audiences (K-12), engineering seminar.

Demo
presentation presentation fall 2014

Next Steps

 * Design in 3D CAD software
 * Build many models
 * Build balance to check lift
 * Structure a competition, figure out how to make a sanctioned competition
 * Test various model designs to the point that can predict performance