Engineering Design Process
Define the problem
We as a group have been chosen to design and build a model rocket that will launch into the air, as well as a landing mechanism that will help keep the rocket from crashing and keep the human (egg) alive. We have a specific materials that we would be able to bring and which ones we can't which increases the challenge. We also have a budget which we have to look after a lot to make sure we don't spend too much money on this. On this website we also have to document everything we do, so later on we know what we did on a certain day. There's also some form of competition that we have to look out for since another group may want to steal our ideas.
Generate Concepts
Some ideas that we have come up with are rockets that are based off the way we protected the egg. For example we came up with a design with a nose cone with the egg in it. We found this idea through amazon, sounds crazy right? Well we were looking for new ideas that we didn't already know. So we went to amazon and search for rockets that holds eggs. We came across one design that put the egg in the nose and we really like this design. Most likely we will end up choosing this design. We like the design because it has a safety protected pop for the egg to sit in during its harsh flight to orbit. After looking this plan over carefully we think this is the best opposition for us to use.
Develop a solution
For our design we decided to use the base of our rocket to hold the egg, so when the nose cone ejects with the parachute, it will be safe inside the rocket. We've decided to use a lot of cushioning to make sure that the egg doesn't bounce around and crack inside the rocket. We've used materials like bubble wrap and sponge to help with that part. Our nose cone originally was a sort of curved cone shape, but because of complications we had to make it a straight cone in order for it to work with our design. So our rocket design will actually work and will hold the egg and the engine but there will need to be some changes. Our parachute isn't big enough for the entire rocket to land safely without crashing so we need to make that bigger. Because of some tests that have been done, everyone had to redesign some parts of the rockets. Our rocket now has to weigh a max of 3.0 grams or less instead of 4.0 like it was before. Also instead of using a regular egg, we have to use a quail egg to we had to work around that because of the added weight and smaller size. The quail egg is also a lot more fragile than a chicken egg so we have to be more careful when redesigning our landing contraption. So we decided to cut some weight off my cutting some parts of the clear tube inside of our rocket since that's what mainly taking up all of that weight. We're also shaving off part of the end of our nose cone, because a lot of that hangs off and we need to loose as much weight as possible off our design without changing anything drastic and messing up everything.
Egg Drop Test
Design Choices
We can assure our egg will not crack during the drop test because we have made the top of the rocket a cage for the egg. The cage is made of bubble wrap and sponge to insure that the egg is kept still at all times. We choose to use bubble wrap around the egg because we knew this would hold our egg still and keep it from breaking inside our rocket. We always see real life examples of bubble being used to keep things from breaking such as shipping items. About every shipping company uses bubble wrap because it is a great material to use to keep things from breaking. We also choose to 3D print our nose cone. We did this because 3D printing is precise and accurate unlike our building skills and aerodynamics is very important. NASA even said themselves that model rockets most important feature is the aerodynamics of the rocket.
Test Results
After dropping our egg, we decided we needed a new parachute because our current one did not work. Our egg survived thanks to our sturdy cage but, the parachute did nothing from making it plummet to the ground. The contraption fell to the ground in 1 second, which is a very fast fall if you ask me. The parachute did deploy but it wasn't able to slow the fall. Our main change will be to use something more like a target bag as a parachute because another group used a target bag and the egg floated down nice and easy.
Center of Pressure Calculations
SA of Fins 4.25 x 2.25 / 2 = 4.78125 in2 - 1 x 9/16 / 2 = 4.5 in2 4.5 x 2 = 9 in2
Thickness of fins: 1/8 in 3.25 x 1/8 = .40625 3 9/16 x 1/8 = .4453125 3/8 x 1/8 = .046875
Total SA of Fins = 9.8984375 x 3 = 29.6953125
Sa of Cylinder= 2 x pie x 2.5in x 10in = 157.079633 in2
SA of Cone= pie x 2 x square root of H2 + R2= 20.116 in2
Distance of Cone: 12 ½ in
Distance of Fins: 1 1/16 in
Distance of Middle of Body: 5 in
Distance x Surface Area =
Fins= 29.6953125 x 1 1/16 = 31.5512695
Cylinder= 157.07933 x 5 = 785.398163
Cone= 20.116 x 12.5 = 251.45
Add all of the SA totals =
29.6953125 +
157.07933 +
20.116 =
-------------
206.890645 in2
Add all of the totals =
31.5512695 +
785.398163 +
251.45 =
-----------
1,068.39943 / total surface area
1,068.39943 / 206.890645 = 5.16407802 Center of Pressure
First in Flights Egg Drop Test
We can assure our egg will not crack during the drop test because we have made the top of the rocket a cage for the egg. The cage is made of bubble wrap and sponge to insure that the egg is kept still at all times. We choose to use bubble wrap around the egg because we knew this would hold our egg still and keep it from breaking inside our rocket. We always see real life examples of bubble being used to keep things from breaking such as shipping items. About every shipping company uses bubble wrap because it is a great material to use to keep things from breaking. We also choose to 3D print our nose cone. We did this because 3D printing is precise and accurate unlike our building skills and aerodynamics is very important. NASA even said themselves that model rockets most important feature is the aerodynamics of the rocket. After dropping our egg, we decided we needed a new parachute really bad. Our egg survived thanks to our sturdy cage but, the parachute did nothing from making it plummet to the ground. The contraption fell to the ground in 1 second, which is a very fast fall if you ask me. The parachute did deploy but it wasn't able to slow the fall. Our main change will be to use something more like a target bag as a parachute because another group used a target bag and the egg floated down nice and easy.
Final Launch Reflections
