Rubber band Powered Plane

Kourtney Henderson, Rachel Lenhart, John Scott, Seth Pierson, and Chris Cihlar

Problem StatementTo analyze the flight of a typical rubber band powered model airplaneTo construct an improved and larger scale model of the plane from scratchTo increase the hang time of the toy despite the increase in size

Background

Planes are simple and small, allowing for a short hang time.Most of the toys fly for only 12 to 15 seconds, covering 250 to 300 feet. Difficult to play with or measure hang time because it flies awayThere is only one set of wings, so the amount of lift is limited.Although designed for family projects, construction time lasts less than 5 minutes.

Design

Biplane design to increase surface area of wings, therefore increasing lift and hang timeFlies in circles to the left to measure flight time more efficientlyConstructed from Balsa Wood to maintain low weightPlastic covered wings to increase lift, decrease air resistance, and to avoid the weight of solid balsa wood wings

Materials Used

Yard long rods of balsa woodLite-weight wooden propellerRubber bandsFood City grocery bagWood gluePush pinsWax paperMetal rodDuct and masking tape

Construction Process

I. Used modified, scaled plans as a template for wings, tail and body.

II. Used wooden blocks to hold wings to get proper angle on wings.

III. Covered wings and tail with plastic bags.

IV. Made necessary modifications to body to accommodate biplane design.

V. Attached wings and tail to body, as well as cross braces for wings.

VI. Constructed and attached propeller mount and metal hook for rubber band.

VII. Modified original mount to reduce friction and balance propeller by adding spare pieces of wood and push pins.

Problems

Couldn’t find long enough rubber band, linked many smaller ones together instead.Metal rod too thick to make proper angle, used hammer to get best possible shape.

Original tail design too weak, modified by increasing glue surface area.Too much friction, wobbliness in propeller, used multiple push pins to elevate and wood block to stabilize.

Our Plane

First Results

Hang time comparison: prefabricated plane: 6.2 sec constructed plane: 3.1 secOur plane flew forward for only a short time before stalling and beginning to glide backward and forward until hitting the ground.

Results after Corrections

Correction: added weight to the nose

Result: stopped

stalling, increased hang time by approximately .3 seconds

Correction: removed the lower wing

Results: decrease in drag, smoother gliding, increased hang time by approximately 1 second

Conclusions

The construction of the propeller was a problem. The metal rod began to deform the wood and the duct tape began to give out causing some of the failure. The connection between the rod and the propeller was not secure enough to hold at high rates of spinning. The propeller wasn’t large enough to create enough air flow.

The spin speed of the propeller reduced rapidly and was not sufficient enough to create air flow. The additional wing would have provided more lift, but without appropriate propeller power and air flow there was too much drag.

References

http://travel.howstuffworks.com/framed.htm?parent=airplane.htm&url=http://www.eskimo.com/~billb/wing/airfoil.htmlhttp://travel.howstuffworks.com/airplane.htmhttp://freeflight.org/jlf/beginners_corner/whammy_series/whammy.htmhttp://www.answers.com/topic/biplanehttp://www.casde.iitb.ac.in/IMSL/video_FP/design.htm