CPSS Projects
Level 1 Certification Rocket Nose Cone
Over the course of the 2021-2022 Fall and Spring Quarters, Cal Poly Space Systems (CPSS) worked in groups of about 10 members to design and construct level 1 certification rockets. Group members were individually assigned a component of the rocket to research and design, which would then be assessed against other groups' designs. At the end of this design portion, the best components were chosen and a club-wide rocket design was put into place, with each group doing their best to construct it themselves.
The nose cone shown on the left was the result of a combined effort by my peers and myself, which ended up being manufactured for each of the rockets launched.
In my group, I was tasked with researching and designing the nose cone. After considering several styles, it was clear that a Haack Series nose cone would be the best choice for our rocket, which was based on which one would result in the highest altitude achieved.
The Haack Series nose cone is a mathematical function derived to achieve the lowest possible drag force that is plotted over a set length and then rotated about an axis to achieve a 3D object. This function is provided on the right, where it shows that there are two different types of Haack Series cones, an "LV" and "LD".
Between the two, the LD-Haack was shown (based on the graph on the left) to produce the least amount of drag for the subsonic flow regime that the rocket would be experiencing, and therefore that was the equation chosen.
For the dimensions, the rocket diameter was set to be 6.4 cm, and thus the length of the nose cone was a design consideration that I had to figure out. The dimension of length for nose cones was most commonly characterized in terms of its fineness ratio, a proportion of length to diameter. Based on several articles written on this subject, most sources claimed that an ideal fineness ratio for rockets that travel through subsonic regimes is 5:1. After considering other design variables such as mass, I went with a fineness ratio of 4:1 since it seemed to be a good compromise between drag reduction and nose cone mass.
A graph illustrating the relationship between fineness ratio and drag coefficient in a subsonic flow regime
Cross-Section of 25.6cm Long 6.4cm Diameter LD-Haack Nose Cone
After plotting the equation in an online graphic calculator and mirroring the function over the x-axis, the displayed cross section of the nose cone was achieved.
After the above cross-section was approved by members of the group, I moved on to create a 3D model of the nose cone in SolidWorks using an equation-driven curve that was rotated about the x-axis.
Finally, the model shown to the left was created and uploaded to the Google Drive our group was using throughout this process. After a club-wide decision, this ended up being the nose cone design that was set to be used on all the rockets that would be built by each group.
After adding a portion that would connect to the actual inner portion of the top of the rocket, the model was converted from a SolidWorks file into one that could be used by a 3D printer in order to print out enough nose cones for the entire club to use on their rockets.
The final product, shown above, is our group's level 1 certification rocket that was launched as a part of a Friends of Amateur Rocketry (FAR) event in the Mojave Desert on February 12, 2022.