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

Build an airplane to compete in a Free flight competition.
video of competition

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.

Design

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

Design Attempt 1

Making of the Air plane
Air Plane Floating
Finishing the plane
Putting everything together
Proppelar of the airplane
Front Wing
Wood being soaked to make it flexible
working on front wing 2
working on back wing
Propellar with rubber band
Top view of what is build so far
Porcelain Film
Complete view of front wing
Another view of front wing
Porcelain film being put on the wing
Top view of the wing with porcelain film
Top view of all the parts completed
starting on propeller
Putting on the plastic
Making of the Propeller
finishing the propeller ]
creating angle for propeller sides
Putting film on the side of propeller
Both sides of the propeller
Wings being attached to the body of the airplane
Another view of wings attached to the body
Another view of wings attached with body
Bottom view of the airplane
Coils attached for propeller
coils used to attach propeller
Airplane testing 1
cresting stryofoam propeller 1
sanding the half of propeller
two halves of styrofoam propeller
creating angle of styrofoam propeller 3
Airplane final testing
Attaching base
Cutting
First propeller

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

Fall 2014

Design Attempt 1
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.

Center of Gravity Test

No need to make a complicated Center of Gravity test. All that is needed is something to balance the plane on.

Front
Side
Top

The blue model is the plane without its front wings. The pink model is the object for the plane to balance on. The point where the plane stays balanced is the center of gravity. When the center of gravity is found, the front wings can be placed over it.

We have been using this test since Project 2 Week 1. We have been using a 5.25" computer drive bay cover (Dimensions: 5 3/4" * 3/8" * 1 5/8") to test the center of gravity.

Place model plane on top of drive bay.
Adjust plane until it stays balanced on top of the drive bay.
Mark point where plane stays balanced.
Place front wing centered on top of mark.

If propeller is too big, hang front end off of a table.

Using the balance prop (5.25" drive bay), the Center of Gravity can be found very simply.
Close-up on the balance prop.

Testing Protocols

We created test protocols in Project 2 Week 1

Find open area with no obstructions and minimal wind.
Twist propeller in opposite direction of its natural spin 100 times to tighten rubber band.
Hold plane 6 feet above ground in hands, making sure propeller doesn't start yet.
Before throwing, let propeller start spinning.
Throw plane by moving hand forward around 4".
Use stopwatch to count how many seconds the plane stays in the air.
Record other notes (nosedives, heavy tails, any propeller issues, etc.).
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.

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

Example of the curved wing camber found on Wikimedia Commons

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.

Making High AR Wing

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:

Lay out plastic wrap over workspace.
Take 2 coffee stirrers to act as the middle two sticks going long-ways and place adhesive on tips.
Place the 4 coffee stirrers on each tip going long-ways.
Cut 2 coffee stirrers in half.
Glue 2 of the halves to the ends of the outer coffee stirrers to connect the lengths together.
Take the wing lengths and mark at 1/4 of the length and 3/4 of the wing.
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.
Flip wing over.
Wrap plastic wrap around the finished wing tight.

Finished wing. Dimensions: 19.5 in. x 3.5 in.; Aspect Ratio: 2.79
Finished plane.

Horizontal stabilizer was made using 1 coffee stirrer for length and 1/3 a stirrer for the width.

Dimensions for the horizontal stabilizer: 6.875 in. x 2.292 in. Wrapped in plastic wrap in the same way that the wings in Project 2 Week 2

Attached horizontal stabilizer to the fuselage (Dimensions: 10 in. x 0.125 in.). Found and marked center of gravity on fuselage. Placed wing slightly in front of center of gravity.

The plane did not fly as expected. The following is the report put together.

High AR Test Flight

Wingspan: 19.5 in.

Body Length: 10 in.

Weight: 12.8g

Average flight: 0.8 seconds

Flight notes: Definitely tail-heavy. Stalled or backflipped on every throw.

Metal Coil added to front of plane
Metal Coil added to front of plane
Picture is for size comparison between plane and metal coil

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.

High AR Test Flight With Coil

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