Rocket Group 46

Sky High

5,4,3,2,1, Lift Off!

Materials

Card stock

Masking tape

Duct tape

Exacto Blade

Ruler

String

Plastic bag (large enough for a parachute)

Empty 2 liter plastic bottles

Air pump

Rocket launch pad

Water

Hard boiled egg(s)

Padding for the egg

Radar gun

Camera

Procedure

1. Start by designing the rocket. Pick out what kind design you want to use, but keep in mind the rocket needs to be able to deploy a parachute and will need to be aerodynamic. Also consider what fin shape wil be used. Reference sources on canvas and online can be used as a starting point. There also neeeds to be an accesible section for placing the egg, and ideally cushioning should fit inside as well. The rocket also needs some deployment methord for the parachute, or else the rocket will nosedive and break the egg. Keep a camera handy if you want to document the entire process.

2. Start to build your robot. Prepare the bottles to be used for the rocket, but keep the bottle which will hold the pressure completely intact. Additional water bottles may be added to increase height and strength. Use duct tape to cover up any cardboard (if any is used) to prevent it from getting soggy and for structural integrity.

3. Prepare the rocket for launch. Fill the propulsion bottle 1/3 of the way with water. Place the egg in its place and pack the parachute.

4. Set up the rocket for launch. Lock the rocket on the launch pad and attach the air pump to the launcher. Pump air until it is at 75 psi, then get ready for launch. Ideally, have two other people at hand, one with the radar gun in position and another with the camera in hand.

5. Launch the rocket. Make sure to have safety glasses on and record the initial velocity and have a full video. The video will be used to pull time from. After launch, check the egg compartment and take note whether the egg survived.

Calculations

Time of acceleration

    o.15+0.16+0.14/3 = 0.15 s

Time to reach peak after fuel runs out

    1.53 + 1.57+ 1.58/ 3 = 1.56 s

Time of descent

    2.56+2.57+2.54 /3 = 2.56 s

These times where taken by using a stopwatch to calculate the time between stages.  We then averaged the results to find the time of each stage.

Velocity 

78 km/h x 1000 m/ km x h / 3600 s = 21.67 m/s

Mass 

1.180 kg

Upward Acceleration / Height

Although our height for this round was only 60 feet, our other run had a height of 85.9 feet.  This was calculated by replacing the times in these calculations with 0.1833 s for t1 and 2.234 s for t2.

Downward Acceleration 

This acceleration was calculated by using the 18.52 m as a starting height and 2.56 s for time, calculated by averaging the values of stage 3.

Free Body Diagram

Fa stands for force of acceleration, mg stands for the weight of the object due to gravity and Fp stands for force of the parachute.

Force Average

This force average is the average force that is exerted during the first stage of the rocket.

Conclusion

Ultimately, we are very happy with the performance of our rocket despite not replicating the same degree of success we had on our practice runs. The main point of revision for our team in the future would be the nose cone/parachute deployment. We are very proud of our rocket’s body and fins, and feels as though we nailed the modular separation design; however, since we based our rocket’s modular separation on the nose cone deploying at the peak of flight, we placed all of our eggs in that basket. If given the opportunity, we would alter our nose cone to extend taller, and thus flay out further to create more drag during our rocket’s first brief moments of free-fall after peak height.

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