Space Apps Challenge 2018

Launch Methods (En.wikipedia.org, 2018)

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We did a bunch of research into alternative methods of getting satellites into space. Such as different launch methods, how much fuel it would cost for a two stage rocket just for satellites or whether a 1 stage rocket is better than a 2 stage rocket.

We looked into the physics behind our various launch methods. One of our ideas was to use a "Space Gun" (aka a Verne Gun) which is essentially a massive gun that can either be in the water or dug into the ground, this would then launch the rocket that contains the satellites into space either via Hydraulics as we had the idea of putting a 2km(ish) long barrel into the bottom of the Marianas Trench made entirely out of carbon fibre to withstand the pressure. The idea was to then use the pressure from the Marianas Trench which is 15,750 psi to launch the rocket off into space.

Another method we came up with was using a similar method to how a railgun works. The idea would be to have to magnets that travel up barrel of the gun as fast as possible. The idea to make this work would be to put the shuttle inside a casing that is magnetic, this casing would then split off of the shuttle in launch. Ideally we would like this casing to be reusable so that we are able to keep the cost of these launches as low as possible.

Although, we finally decided to go with a 2-stage rocket we feel that a space gun using a similar method to how a rail gun works would be doable in order to send a rocket into space.

Fuel Types

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We then investigated what would be the most cost effective type of fuel to use to launch the two stage rocket. We first started off with comparing the pros and cons of both Liquid Fuel, Solid Fuel and also Gel fuel. However, we then later realised why people never really use Gel Fuel when they are trying to launch a rocket.

Pros of Liquid Fuel

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• Liquid fuel is a lot cheaper.
• Has no positive feedback loop.
• It is also able to be throttled to control speed.

Cons of Liquid Fuel

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• Requires more space to store than solid fuel.
• The overall cost of the rocket is also exponentially more.

Pros of Solid Fuel

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• You are able to fit more into a singular space due to the molecules of a Solid Fuel being closer than a Liquid Fuel.
• Solid fuel is mostly used for initial boosters as they are not needed to be limited or controlled.

Cons of Solid Fuel

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• Has a lower specific impulse than Liquid Fuel.
• It is unable to be controlled, once the fuel is ignited it will keep burning until the fuel itself is depleted.
• Solid fuel itself is intolerant to cracks and voids and it often requires post-processing such as an x-ray scan to identify any faults.
• The positive feedback loop that is needed can lead to catastrophic failure of the entire system, which is usually controlled by the case itself failing or any damage to the nozzle system itself.

Pros of Gel Fuel

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• Gel Fuel itself is the best of both worlds as it is able to be stored in a similar space as a solid but is also just as controllable as a liquid.

Cons of Gel Fuel

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• However, it produces half the amount of energy as Liquid fuel meaning we would require twice as much Gel Fuel.

Physics

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• The Rocket Equation: Describes the motion of a vehicle following the principles of a rocket.
• Δv=ve ln (m1/m0)
• This allows a rough estimate of total launch mass to be found.
• m0=m1 e^(Δv/ve)

Resources

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En.wikipedia.org. (2018). Space gun. [online] Available at: https://en.wikipedia.org/wiki/Space_gun [Accessed 20 Oct. 2018].

grc.nasa.gov. (1997). Gelled Liquid Hydrogen: A White Paper. [online] Avalible at: https://www.grc.nasa.gov/WWW/Fuels-And-Space-Prope...