Aeronautical Engineering/Rocket questions


Dear Dr.Janus,

      Hello, my name is Anna, and I am a student in Brewster High School in New York. I am currently enrolled in a Pre-Ap Chemistry class. For our final lab report we are required to ask an expert about rockets. My specific rocket is the Atlas Able. I would sincerely appreciate if you would be kind enough to answer any of the questions below.
1)What is the difference between using solid fuel and liquid fuel?
2)Are there any differences between the different Atlas rockets?
3)How does the liquid engine work?
4)How do you know if the rocket is powerful enough to take off with it's payloads ?
5)What type of rocket would be suitable for deep space travel?

Anna Yu

A solid fuel rocket is less controllable than a liquid fuel rocket but they are generally more stable and easier to work with.  Once ignited you have to let it "run" til all the fuel is used up.  Liquid rocket engines are throttlable and can be shut off.  
I am not that familiar with the Atlas Able rocket.  I'm gonna suggest you look that one up online to get the specs for it.  
A liquid engine works by bringing together the liquid fuel (like hydrogen, kerosene, etc) and the oxidizer (liquid oxygen) and then igniting the mixture in a combustion chamber...  the hot exhaust gas then passes through a nozzle which converts the thermal energy (heat of the exhaust gases) to kinetic energy (i.e. the nozzle accelerates the gas out of the end of the rocket engine).  The rocket thrust is the reaction to the momentum of the exhaust gases leaving the engine...
basically the rockets thrust must exceed the weight of the rocket + payload ...  the excess thrust (force) is then used to accelerate the rocket (based on Newtons second law)
Several rocket design concepts have been proposed for deep space travel...  basically after escaping the Earth's gravitational pull (where it becomes more negligible) you need a low thrust rocket engine that maintains a constant acceleration on your rocket (if you have humans aboard).
There are ion propulsion systems, nuclear propulsion systems, conventional chemical rocket engines, solar sails, gravity assist mechanisms...  to name a few means of deep space propulsion

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Mark Janus


I can answer questions about aerodynamics (high speed and low speed), internal fluid flow, computational methods (CFD, some design, etc.)


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