Nakuja Project Blog

  Theory: ·          Rocket motion is based on Newton’s second law of motion ( 𝐹 = 𝑚𝑎 ). ·          Rocket motion is a variable mass problem i.e rocket mass changes as the propellant is used up. ·          Air density varies with altitude. ·          In flight, a rocket is subjected to four forces: thrust, lift, drag, and weight. Governing equations: 1. Drag equation 𝐷𝑟𝑎𝑔 𝑓𝑜𝑟𝑐𝑒 = 𝐶𝑑 ∗𝜌𝐴𝑣/ 2 Where: a)       Cd=drag co-efficient (obtained from the NASA’s Glenn Research Centre website) b)       Ρ=air density (I used the ISA model because using the standard ideal value of 1.2kg/m3 would not reflect the practical air density conditions encountered during rocket flight) c)       A= rocket area (frontal) N/B: the area used i.e whether surface or frontal affects the drug force d)      V= rocket velocity 2. Weight 𝑤 = 𝑚 ∗ 𝑔 MATLAB Simulation Model About the Model: ·          Thrust is imported from excel file into a work space variable. I

  Static Firing Test no. 2

Motor Design The propellant of choice was Potassium Nitrate(Oxidizer) and Dextrose(Fuel/Binder). An oxidizer to fuel ratio of 65%:35% was used. The propellant was cast into one grain with a  total weight of 24g.  The grains had an outside diameter of 24mm and a core diameter of 7.2mm.  Prior to static testing a simulation using openMotor was done for a theoretical performance of the motor.  Motor Casing The casing of the motor was made from ¾ inch PVC. The top side(bulkhead), as well as the nozzle, were to be made from tile cement.  The nozzle was designed with the following dimensions: Throat diameter - 6 mm Exit diameter - 6 mm Throat length - 35mm Divergence half angle - 0 degrees Convergence half angle - 0 degrees Motor Fabrication The KNDX propellant was cast as follows:  The nozzle and endcap were fabricated using tile cement(grout). The grout is mixed with water in the ratio of 3:1 by weight and poured into the pipe. The cast is left to sit overnight. The nozzle is made by drill

Prep work This is a summary of the work done in preparation for the static testing. These activities were: Fabrication of a test stand- We made a test stand as well as wrote relevant code to measure ,analyze, visualize and store data during testing. Research work on PVC motors- We did research on PVC motor design. A link to a major resource is attached. Link: https://www.nakka-rocketry.net/pvcmot4.html#Intro We also developed a remote ignition system by repurposing parts of an old toy car. Motor Design 1.Propellant The propellant of choice was Potassium Nitrate(Oxidizer) and Sucrose(Fuel/Binder). An oxidizer to fuel ratio of 65%:35% was used. The propellant was cast into two grains with a  total weight of 34g.  The grains had an outside diameter of 24mm and a core diameter of 7.2mm.  Prior to static testing  a simulation using openMotor was done for a theoretical performance of the motor.  A link to this data is attached: https://github.com/nakujaproject/felixResearch/blob/main/Motor%2

Introduction  The N-2 Motor is designed to fly on the N-2 rocket to be launched in September. The rocket is set to target an altitude of 300m carrying a small payload. The motor is aimed to be reusable and accommodate different motor sizes from the length of 40mm(Test spec) to 270mm. The propellant to be used in the motor is also changeable.  Basic Dimensions and Configurations The propellant is free-standing with restricted burning on the walls with the grain being basically cylindrical. The motor is designed to fail in case of overpressurization in an axial direction. The three bulkhead bolts seized to shear at a pressure of approximately 16MPa, blowing off the bulkhead. The casing burst pressure is higher at around 80MPa.  Nozzle The nozzle is a conical shape machined from aluminium 6063. The convergent and divergent half angles are 35 0  and 12 0 . The nozzle is attached with 4 M8 x 1.25 class 10.9 steel bolts with a minimum yield strength of 1040 MPa. E ach bolt can withstand a mi