2010 MESA CompetitionThe Mercury/Redstone (Sort-of) Anniversary Suborbital Egg Toss Leonard Vance

24 October 2009

“The purpose of the missile business is to make the landing site more dangerous than the launch site”

Wernher Von Braun

Objective of Competition How far can you launch an egg with a 2 liter

bottle rocket without breaking it. Single launch for score Minimal material restrictions – NO Metals MESA supplies launchers to each school

Summary of Launcher Setup

Trigger Block

Bottle Support

2 Liter Bottle

Egg Canister

Pressurization Tube(ALWAYS over trigger block!)

45 deg. Launch Angle

Lanyard

Summary of Specs (1 of 2) The bottle rocket must be made up of one 2-liter pop bottles. Attachments are allowed to the pressurized bottle as long as

they do not compromise its pressure capacity (i.e., duct or masking tape are safe. Paint, hot glue, super-glue and/or plastic glues are NOT safe).

An egg capsule must be incorporated into the design. The capsule may or may not separate from the pressurized bottle.

The maximum mass of the empty rocket assembly shall be no more than 450 grams.

The maximum length of the rocket assembly shall be no more than 70 cm.

Rocket components may or may not separate during flight. Separated components not containing the astronaut are not required to meet any distance or accuracy requirements.

Summary of Specs (2 of 2) Students shall be responsible for determining their own

launch pressure. The maximum allowed shall be 75 psi. The launch lanyard shall be greater than 4 meters long. The official distance is the projected downrange distance of

the egg container’s initial impact point. Any initial impact point more than 10 meters off center line is disqualified.

If the astronaut (egg) is damaged in any way upon retrieval, the distance score is divided by 10. If the ‘astronaut’ is seen to disintegrate in flight, the entrant is disqualified.

Immediately following the launch, team members will orally respond to a standard set of questions

The entry with the highest distance plus oral score will be declared the winner.

Maximizing Flight Distance Best pressure – 75 psi Best water level – about ¼ full Distance: upwards of 100m if egg not protected

But that said….

Distance thrown is not likely to be the hard part of this project

Egg Survival Tips Prevent local pressure to any

part of the shell Support the egg carefully in

the impact direction Compress around the center

of the egg Increase deceleration distance

with compressible material

Eggs are tougher than you think!

Impact Velocity

Sharp Pointy Things(Like Styrofoam Peanuts!)

Egg Survival Tips Prevent local pressure to any

part of the shell Support the egg carefully in

the impact direction Compress around the center

of the egg Increase deceleration distance

with compressible material

Eggs are tougher than you think!

Foam

Impact Velocity

LowPressure

HighPressure

Foam

Egg Survival Tips Prevent local pressure to any

part of the shell Support the egg carefully in

the impact direction Compress around the center

of the egg Increase deceleration distance

with compressible material

Eggs are tougher than you think!

Impact Velocity

Egg Survival Tips Prevent local pressure to any part

of the shell Support the egg carefully in the

impact direction Compress around the center of the

egg Increase deceleration distance with

compressible material

Eggs are tougher than you think! They will ‘scramble’ in the shell before breaking

Impact Velocity

CompressibleMaterial

Hard Outside

Shell

Testing Tips Figure out a way to test early and often: This

improves student participation and learning Astronaut canisters can be stand-alone tested

Increase velocities until egg breaks (not the other way around)

Measured survival velocities can be used to predict corresponding distances

Launches can be adjusted until distance is correct with an ‘egg surrogate’

Only then should a real egg launch be tried.

Getting Launch Distance from Astronaut Impact Velocity

d

Classic 45 deg launch TrajectorySimple Newtonian Mechanics – No air friction assumed

v

d = v2

gWhere:d = flight distancev = initial velocityg = gravity = 9.81 m/s2

Measure velocity of egg canister tests against the wall, and us it to adjust the rocket to fly that distance (or a little less…)