1. The propellant combination is one of the most significant factors in engine sizing. Nitrous Oxide, N2O is our oxidizer, and Isopropyl Alcohol, IPA is our fuel. IPA was selected as fuel due to its low cost and accessibility.

2. Engine sizing is constrained by three main variables, chamber pressure

   Eazy math inline
   body (P_{c})

   , thrust

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   body (F_{t})

   , and mass flow rate

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   body (\dot{m})

   . We used a Simulink simulation to decide on an

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   body F_{t}

   of

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   body 2500N

   and metallurgy and COTS valve/fitting pressure contracts ratings to arrive at a

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   body (P_{c})

   of

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   body 2500kPa

   /

   2500 \mathit{kPa}

   or

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   body 362.6Psi6\mathit{Psi}

   .

3. Using NASA CEA. We input

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   body P_{c}

   ,

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   body P_{e}

   , and a number of mass fractions

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   body \mathit{MR}

   for our N2O oxidizer and IPA fuel. CEA allows you to simulate various mass fractions. We chose 4.0 as it gives the best ISP performance, this burns hot but not as hot as a more OX-rich mix. CEA outputs the

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   body {M}

   ,

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   body {\gamma}

   (equivalent to

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   body \frac {C_{p}} {C_{v}}

   ),

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   body \frac {A_{e}} {A_{t}}

   ,

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   body {V_{e}}

   , and ISP.

4. The following parameters are fed into a Matlab script:

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   body \dot{m}

   ,

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   body \mathit{MR}

   ,

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   body P_{c}

   ,

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   body P_{e}

   , and

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   body L^\star

   (L* is somewhat arbitrary and selected) as well as chemical properties. m_dot is adjusted! We chose an L* of 1 m, and m_dot 1.1 kg/s. That yields V_c. We pick 0.15 m L which gives a D_c of 7.73cm and exit diameter of 6.3 cm and a throat diameter of 2.99 cm.

Variable Table