Forming a group: Gabriel and I both work together well, and get along super well. Due to this we decided to become partners. We both have had some background knowledge on rockets, which is going to help. Also we did some research on rockets, which is really gonna help out, especially when we are going to be designing our own scratch built engine. This partnership is going to be one that works out also, because last year in Brian's class, my good friend Nolan and I worked on scratch built engines a lot. While picking a partner, I wanted to pick one that will stay with me for the entire project, and someone that wants a good grade also.
Familiarizing my self with scratch built rockets: With rocket engines, there are two different types of rocket engines you can make. These two engines are end burners and core burners. These two engines are a lot different from others. These are the only scratch built engine types we are going to make here at High Tech High.
End Burner Motor: The first engine I would like to start off is the end burner engine, this is an engine that is known in amateur rocketry. A end burner engine is, an engine that has a cylindrical stick of fuel, with no gaps between the casing wall, which in this case is a round piece of cardboard, that can withstand lots of pressure. These engines have a bit of room between the fuel and the ignitor, just enough so the motor can accept the ignitor. The whole point of these engines is immediately after the launch button is pressed, the flame is directed outwards, which in this type of engine it is formed into a hemisphere, with the whole surface area of the flame and thrust greater than the propellant grains cross section, which is kinda hard to tell what exactly that means. With this type of engine, the initial surge of high thrust and pressure is at the start of the motor, then that quickly goes away as the burn rate changes into a shallow cup. When this happens all of the fuel pretty much is burned up, and the pressure and the thrust is all gone. These engines are used a lot, and worth making if they are properly made. The whole point of these motors are to have a constant level of thrust for a long period of time. As these engines are burning, it is a long time. Due to this, what happens is the inside walls of the motor get hot, and catch on fire most of the time. The reason for this, is most of the time the cylinders are made out of paper.
Familiarizing my self with scratch built rockets: With rocket engines, there are two different types of rocket engines you can make. These two engines are end burners and core burners. These two engines are a lot different from others. These are the only scratch built engine types we are going to make here at High Tech High.
End Burner Motor: The first engine I would like to start off is the end burner engine, this is an engine that is known in amateur rocketry. A end burner engine is, an engine that has a cylindrical stick of fuel, with no gaps between the casing wall, which in this case is a round piece of cardboard, that can withstand lots of pressure. These engines have a bit of room between the fuel and the ignitor, just enough so the motor can accept the ignitor. The whole point of these engines is immediately after the launch button is pressed, the flame is directed outwards, which in this type of engine it is formed into a hemisphere, with the whole surface area of the flame and thrust greater than the propellant grains cross section, which is kinda hard to tell what exactly that means. With this type of engine, the initial surge of high thrust and pressure is at the start of the motor, then that quickly goes away as the burn rate changes into a shallow cup. When this happens all of the fuel pretty much is burned up, and the pressure and the thrust is all gone. These engines are used a lot, and worth making if they are properly made. The whole point of these motors are to have a constant level of thrust for a long period of time. As these engines are burning, it is a long time. Due to this, what happens is the inside walls of the motor get hot, and catch on fire most of the time. The reason for this, is most of the time the cylinders are made out of paper.
Core Burner Motor: The second motor I would like to end of with is called a core burner motor, these motors are also used a lot in amateur rocketry. These have a bored out hole, or also known as a core running through the exact center of the fuel of the motor. What happens in these motors when they are ignited is, the the flame immediately spreads to the very end of the motor, lighting the entire length of the core as the flame travels up the core. When the flame is traveling out the back end, it is the exact shape of an expanding cylinder, which is very interesting to me. There are several of ways you can core an engine. For example, if you have a small nozzle and a short core the pressure in the chamber will not start out fast nor will the thrust, but they will start going when the burnout starts out. The when you have a larger nozzle and a much larger core, then the values are way higher then most. If you make a motor with a huge nozzle and a long core, the pressure build up is way higher and the trust gets as high as 50% of the maximum.
The Two Types Of Rocket Fuels: There are two types of fuels that were told to us today in class, and these mixtures can very. The two types of fuels are, potassium nitrate/sugar or black powder.
Potassium Nitrate/Sugar: The first rocket fuel I would like to start off with is, potassium nitrate/sugar. This propellant consists of 3 groups, they are the fuel, the oxidizer and the additive(s) which sometimes is optional. In this case, the fuel is sugar. You can use all types of sugar(s) but the most used sugar is sucrose. And as an oxidizer, what is used is KNO3, which is potassium nitrate. With rocket candy the average ratio for the fuel is 65% KNO3, and 35% sugar mix. Sometimes people add 1% iron oxide, which makes the thrust rate amazingly higher. These engines can been melted down to a paste, or can be pressed with 1,000's of pounds. The reason for it needing to be packed will a 1,000 pounds of pressure, is you cannot have any air pockets in the motor. If you do, your thrust will go down and your engine will not work that great. I have has some experience with these engines, and really haven't had a good experience with these for some reason. By time, Gabriel and I would like to protect this fuel.
Black Powder: The second rocket fuel I would like to finish off to is, a black powder mix rocket motor mixture. Black powder is usually used in model rocket motors. What these motors consist of is, charcoal, sulfur and potassium nitrate. Everyone has there own ratio opinion, but the most used one is 75:15:10. When people are making these engines, the amount of each component can be adjusted, which will change how the black powder burns. Most of the time these black powder rocket motors are only produced in small sizes, due to these being extremely expositive. A lot of people are saying, a black powder rocket motor, partially cored with a tiny core going through the whole thing is a very good way of doing it.
Our Design:
Potassium Nitrate/Sugar: The first rocket fuel I would like to start off with is, potassium nitrate/sugar. This propellant consists of 3 groups, they are the fuel, the oxidizer and the additive(s) which sometimes is optional. In this case, the fuel is sugar. You can use all types of sugar(s) but the most used sugar is sucrose. And as an oxidizer, what is used is KNO3, which is potassium nitrate. With rocket candy the average ratio for the fuel is 65% KNO3, and 35% sugar mix. Sometimes people add 1% iron oxide, which makes the thrust rate amazingly higher. These engines can been melted down to a paste, or can be pressed with 1,000's of pounds. The reason for it needing to be packed will a 1,000 pounds of pressure, is you cannot have any air pockets in the motor. If you do, your thrust will go down and your engine will not work that great. I have has some experience with these engines, and really haven't had a good experience with these for some reason. By time, Gabriel and I would like to protect this fuel.
Black Powder: The second rocket fuel I would like to finish off to is, a black powder mix rocket motor mixture. Black powder is usually used in model rocket motors. What these motors consist of is, charcoal, sulfur and potassium nitrate. Everyone has there own ratio opinion, but the most used one is 75:15:10. When people are making these engines, the amount of each component can be adjusted, which will change how the black powder burns. Most of the time these black powder rocket motors are only produced in small sizes, due to these being extremely expositive. A lot of people are saying, a black powder rocket motor, partially cored with a tiny core going through the whole thing is a very good way of doing it.
Our Design:
Our Goal: Our design is a full cored black powder engine, that is going to be very effective. Our nozzle throat size is going to be 3/16 of an inch, and our core diameter is going to be 3/16 of an inch. We picked black powder for our fuel type, due to not having good experiences with the potassium nitrate/sugar engines. We are now going to be panning our next engine, to make a more effective engine, that will have even a higher thrust.
Video of Rocket Engine with Thrust:
Video of Rocket Engine with Thrust:
Thrust Curve Graph:
Reflection on how our rocket worked: When we had this rocket engine lit, we knew that it was a great one. As you can see on the thrust curve it starts at 0 and then went all the way up to 2900, which is one of the highest thrusts in the entire 2 grades, which is truly amazing. If you then look at the very top spike, that was something I did not see on any other thrust curve graph. This is something that I don't understand why it occurred, due to this I would like to do some research on it. From seeing this thrust curve graph, it has really opened up my understanding to rocketry.
Final Motor Decision: The motor that we would like to be our final motor is our motor which is the Trident Missile. The reasoning for this is we really liked the way the engine burned, and we liked the way our thrust curve is. For example, if you look up at our curve it initial burn time is .30 of a second and it got to its peak at 2800 (g) of thrust which truly is one of the highest thrusts in the school. We also looked at our motor when it was fully burned out, and it did not have any left over fuel or tar, which that means it burned very clean. Our average thrust was 3.16 (N) which is pretty high for an average thrust. All in all Gabriel and I were very impressed with our final outcome for our motor. The rocket design that we could like to achieve is, the lightest rocket possible with a perfect center of gravity. It was told to us in class, that if you have too light of a rocket, it will loose control and spin all over the place. But we now have talked to JP in class, and he told us that it doesn't matter how light your rocket is, but you want your center of gravity as perfect as possible.
Final Motor Decision: The motor that we would like to be our final motor is our motor which is the Trident Missile. The reasoning for this is we really liked the way the engine burned, and we liked the way our thrust curve is. For example, if you look up at our curve it initial burn time is .30 of a second and it got to its peak at 2800 (g) of thrust which truly is one of the highest thrusts in the school. We also looked at our motor when it was fully burned out, and it did not have any left over fuel or tar, which that means it burned very clean. Our average thrust was 3.16 (N) which is pretty high for an average thrust. All in all Gabriel and I were very impressed with our final outcome for our motor. The rocket design that we could like to achieve is, the lightest rocket possible with a perfect center of gravity. It was told to us in class, that if you have too light of a rocket, it will loose control and spin all over the place. But we now have talked to JP in class, and he told us that it doesn't matter how light your rocket is, but you want your center of gravity as perfect as possible.