Principles of Applied Engineering How to Make a

Principles of Applied Engineering How to Make a Model Rocket

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Set a Goal • Set a specific goal for: • How high you want your rocket to go • How long you want it to take to land • How gently your rocket will land – place an egg inside to see if your rocket can land without breaking it • Or any other goal. Example: Place a small RC car inside the rocket and program it to activate on landing and exit the rocket Copyright © Texas Education Agency, 2017. All rights reserved. 3

Research • Research formulas about rocket stability, the forces on a rocket, and basic rocket construction techniques • Formulas can help you predict how high your rocket will go • Rock. Sim software is helpful to design your software • Nasa. gov is a helpful resource for basic rocket construction Copyright © Texas Education Agency, 2017. All rights reserved. 4

Helpful Formulas • F=1/2 xpxv^2 x. Axcd where F==force of drag, p=density of air, v=velocity of rocket, A=reference area of rocket, cd=coefficient of drag • The reference area is the area seen from the top view of the rocket • The velocity of the rocket can be estimated using Rock. Sim Copyright © Texas Education Agency, 2017. All rights reserved. 5

Formulas Continued • Force is equal to the change in momentum with respect to the change in time • Force=(m(v))(d/dt) • Use a wind tunnel and measure the speed of the wind at 0 seconds and at 1 second. Also find the mass of the rocket at 0 seconds and at 1 second • The force = (final massxfinal velocity-initial massxinitial velocity)/(final time-initial time) • Coefficient of Drag=F/(. 5×p×v^2×A) Copyright © Texas Education Agency, 2017. All rights reserved. 6

Brainstorming • Begin sketching designs for possible rockets • Parts that you should consider are: parachute/streamer, body material and size, nose cone length, engine type, and fins • Also consider placement of the center of mass and placement of movable mass • Use Rock. Sim to estimate how your possible designs will perform • Decide on a design to construct • Order the parts that you need • Order an extra set of parts while you are ordering. You will probably have a few crash landings Copyright © Texas Education Agency, 2017. All rights reserved. 7

Brainstorming Continued • Use Rock. Sim to estimate how your possible designs will perform • Decide on a design to construct • Order the parts that you need early • Order an extra set of parts while you are ordering. You will probably have a few crash landings • Consider making two rockets of different designs so you can choose the best one in the end Copyright © Texas Education Agency, 2017. All rights reserved. 8

Construction Tips • Measure the mass of the parts that you obtained and enter those masses into Rock. Sim – the default Rock. Sim masses may not be the same. Make any necessary adjustments • Include flame-retardant recovery wadding above the engine mount to keep the parachute/streamer from burning • Make a compartment for the altimeter to keep it stable, and drill four 1/8 inch-diameter holes in the body tube around the altimeter casing so the altimeter makes accurate readings Copyright © Texas Education Agency, 2017. All rights reserved. 9

Construction Tips Continued • The parachute must be folded correctly – do not just shove it in the rocket • Use epoxy to glue the fins in place, and consider using epoxy to reinforce the edges of the fins. Be careful with the epoxy. Do not get it on you • The engine should fit snuggly in the engine mount. It may help to put masking tape around the outside of the engine spiraling from top to bottom. This adds just enough circumference to the engine that will fit firmly. This can also work on the nose cone. Copyright © Texas Education Agency, 2017. All rights reserved. 10

Flying • Get a launching site approved. You can not just launch anywhere • Check the weather before you launch. Try to pick the least windy day • Point the launch-stick slightly against the wind when launching • Use a device to detect when a plane is coming • The wind can take a rocket very far. Make sure you know to watch where the rocket comes down Copyright © Texas Education Agency, 2017. All rights reserved. 11

Evaluation • Compare your actual results to your goal and your Rock. Sim results • Make any necessary design adjustments to meet your goal • It may take many flights to find the best solution, so test your rockets far before any deadline to allow for bad weather and time to fix and adjust your rockets • Rock. Sim is helpful, but not always accurate in real life. Trial and error is the best method in the end. You will probably go through many designs and rockets before you find a successful one Copyright © Texas Education Agency, 2017. All rights reserved. 12

Challenge • Create a bottle rocket that can fly 150 feet and come down safely with the use of a parachute. • Carry an egg in the bottle rocket. Build the rocket so that the egg does not break upon landing • A bottle rocket will require more readily available and cheaper materials. This would be a good way to learn about rocket fundamentals before really building the real thing Copyright © Texas Education Agency, 2017. All rights reserved. 13

Bottle Rocket • Materials needed will be: 2 2 -liter bottles, one small plastic cone, duct tape, scissors, string, manila folder, large plastic trash bag, masking tape and a hole puncher • You will use the manila folder as material to make the fins • Pressurized water will be the propellant for the bottle rocket Copyright © Texas Education Agency, 2017. All rights reserved. 14

Challenge • Create a rocket that can safely carry a remote control car or other mobile device, and engineer the device to activate upon contact with the ground, and move out of the rocket tube safely • One possibility: Use an RC car or mechanical bug that has an on/off switch. Include a spring in your rocket that will compress upon landing, and therefore retract, also which would act like a pogo stick and flip the switch on the car/bug Copyright © Texas Education Agency, 2017. All rights reserved. 15

Reference • Hayhurst, Pat. "Mr. Hayhurst's Quick and Easy Bottle Rocket. " Ln. HS Home Page. NSTA, 7 Nov. 2004. Web. 25 May 2010. Copyright © Texas Education Agency, 2017. All rights reserved. 16