Updates
(V.3 & V.3 SE hybrid rocket)
(16/12/2022)What will I do:
I will make a hybrid engine.
This basically means solid fuel and gaseous oxidizer.
I want to do it as the final middle school classwork and to show everybody that we can recycle polyethylene
(PE or HDPE. I will use it as the solid fuel) and turn it into power.
(07/02/2023)Development start:
After numerous hours of reading tons of documents,
literature and watching tutorial videos, I finally decided that I was able to do the calculations for the engine.
The most useful documents were: Rocket propulsion elements (7th edition),
a MIT (Massachussets Institute of Thechnology) aerospace course on EdX and a YouTube video about the calculations.
Also, a lot of time was spent on learning to use the necessary software for the design and calculations
(NASA CEA and Autodesk fusion 360). The CAD software (fusion 360) was easier to learn,
since I already knew how to use it. Meanwhile, NASA CEA was a bit more confusing.
(18/6/2023)Engine test
The engine test was successful. The parameters were not measured, as I have gone over budget, but the burn time was very close to the calculated one. This project is now finished
The basics for calculating an engine is knowing the starting parameters (in parentheses), such as:
- Chamber pressure (4 Bar)
- Exit pressure (1,01325 Bar)
- Burn time (15 sec)
- Force (100N)
Without these parameters, none of the ideal rocket equations can be solved.
Some of this data must be inputted to NASA CEA, which outputs tons of other data used.
Then, using some equations, I was finally are able to calculate the nozzle geometry.
The initial parameters weren’t invented, for example, the pressure was limited by the pressure reducer on the oxygen tank.
The burn time was also limited by the amount of oxidizer
(which was fairly expensive at about €40 a metric liter equivalent to 145g of o2).
The exit pressure is the atmospheric pressure and, finally, the force was determined by the calculations,
the number 100 Newtons really simplified them.
The initial parameters were very different, for instance, the pressure was intended to be 15 Bar.