Newton's Third Law
Newton's Third Law states that for every action, there is an equal and opposite reaction. When we push a book across a desk, we exert a force on the book, while the book exerts that same force back at us; the same applies to rockets. When the fuel is ignited, it pushes downward. An equal and opposite force must match the force due to the fuel (thrust) which propels the rocket upward.
Thrust Graph
Unknown Engine
Below is a graph of an impulse curve of an unknown engine. Using what we know about Estes engines, we can determine what engine is used in this graph. For example, let's take the engine C6-3. The "C" represents the total impulse (area under the curve), the "6" represents the average thrust, and the "4" represents the time delay from when the engine shuts off until the parachute is deployed.
First, the impulse can easily be determined by finding the area under the curve by using a DataStudio smart tool. The impulse is 8.78 Ns, which puts it closest to a C engine which has an impulse of about 10 Ns. The average force, or the "mean" shown on the upper right is 3.82 N. Lastly, the delay time can be found by looking at where the impulse curve ends and where the smaller impulse curve starts. The time delay is about 5.5s. The only engine that is close to a C3-5 or C3-6 (as shown by our data) would be a C6-5.
First, the impulse can easily be determined by finding the area under the curve by using a DataStudio smart tool. The impulse is 8.78 Ns, which puts it closest to a C engine which has an impulse of about 10 Ns. The average force, or the "mean" shown on the upper right is 3.82 N. Lastly, the delay time can be found by looking at where the impulse curve ends and where the smaller impulse curve starts. The time delay is about 5.5s. The only engine that is close to a C3-5 or C3-6 (as shown by our data) would be a C6-5.
Using the same techniques as above, the following two graphs can be determined to be:
Wrong Engine Scenario
The scenario is:
Caroline has constructed an Estes Eggscaliber rocket. She has chosen a raw egg and carefully seated it in the payload section of the nose cone. After inserting the correct amount of recovery wadding and packing the two parachutes, she waits in line to purchase an engine. The engine she selects is a D12-0. Caroline places the engine in her rocket and prepares the igniter and places the rocket on the launch pad.
Caroline has selected an engine that has 0 delay time. That means, as soon as she launches her rocket, the parachute will be deployed. The rocket will be accelerating at a very high rate with the parachute and nose cone out. The parachute may possibly rip, causing the rocket to fly out of control with a high payload, which can cause some serious damage. With the nose cone out, it will most likely fly in a direction other than straight up. There are not many "good" outcomes that can come out of this scenario using the D12-0 engine she selected. She could have used a D12-3 with the egg so that the the parachute deploys at or just before the rocket's peak. Then, the rocket will be going at its slowest so that the rocket with the egg can land slowly and safely to the ground.
Caroline has constructed an Estes Eggscaliber rocket. She has chosen a raw egg and carefully seated it in the payload section of the nose cone. After inserting the correct amount of recovery wadding and packing the two parachutes, she waits in line to purchase an engine. The engine she selects is a D12-0. Caroline places the engine in her rocket and prepares the igniter and places the rocket on the launch pad.
Caroline has selected an engine that has 0 delay time. That means, as soon as she launches her rocket, the parachute will be deployed. The rocket will be accelerating at a very high rate with the parachute and nose cone out. The parachute may possibly rip, causing the rocket to fly out of control with a high payload, which can cause some serious damage. With the nose cone out, it will most likely fly in a direction other than straight up. There are not many "good" outcomes that can come out of this scenario using the D12-0 engine she selected. She could have used a D12-3 with the egg so that the the parachute deploys at or just before the rocket's peak. Then, the rocket will be going at its slowest so that the rocket with the egg can land slowly and safely to the ground.
Big Daddy Engine Possibilities
Estes recommended the following engines: C11-3, D12-3, D12-5, E9-6. The engine I ended up choosing was the E9-6. The E engine would help it reach its maximum altitude. For the first two engines ( C11-3 and D12-3), the parachute would be deployed as it is reaching its peak, while the last two engines (D12-5 and E9-6) would have the parachute deploy as its turning around to come back down. The C engine would have the smallest impulse, followed by the two D engines, followed by the E engine with the greatest impulse. The average thrust for the rockets are fairly similar, though the number given for average thrust varies greatly. Ultimately, I chose the E9-6 engine due it being the engine that would make it reach the highest altitude, but still deploy the parachute in a safe amount of time.