Project Hi-Vis

Project Hi-Vis is a project I have been working on since Summer 2023. The main goal of the project was to build a minimum diameter sounding rocket to learn the standard procedures for constructing, integrating, testing, and flying high-powered rockets. I achieved my L1 high power certification in April 2023. After that, I decided I wanted to start a project that would challenge me and force me to learn new skills.

My primary objectives with Project Hi-Vis were to:

• Learn about standard construction techniques for the various stages of assembly (filleting, fixturing, painting, etc.)

• Become familiar with dual-deploy recovery procedures and hardware.

• Create highly detailed and consistent documentation throughout construction, testing, and flights.

• Maintain detailed CAD models of the entire vehicle and all subassemblies.

• Refine simulations using real-world data to create a highly accurate model.

Kit: Wildman Blackhawk 38

Colors: Black, Orange, Reflective White

Airframe Material: Graphite-loaded fiberglass

Airframe Diameter: 1.6 in OD / 1.5 in (38 mm) ID 

Overall Length: 52 in

Dual-ejection, dual-deploy recovery

Planning of this project began in late April, 2023, shortly after receiving my L1 certification. All parts were received by late May, and that's when construction began. The first thing to be assembled was the fins. This involved first tacking the fins down while constrained by lasercut alignment jigs, then Loctite 9460 Hysol epoxy fillets were created to provide the primary attachment structure.

The next order of business was motor retention. On minimum diameter rockets where the airframe also serves as the motor mount, there is no room for external motor retention hardware. For this reason, I used an "Aeropack" style retainer that is composed of a section of 1.5" OD fiberglass tubing, two fender washers, and a 5/16" eyebolt. The retainer is held inside the airframe using nylon rivets.

The last stage of airframe construction was epoxying the switch band on the coupler tube and drilling holes in the airframe for pressure equalization, rivets, and avionics switch access. The optimal positions of these holes were determined using the CAD model and marked using Sharpie on blue painters tape.

Designing the avionics bay was the most time consuming part of this project. The spacial constraints of a 38mm airframe make fitting even compact flight computers inside very challenging. The flight computers chosen for this iteration of the avionics are a Featherweight Blue Raven Deployment Controller and a Featherweight GPS System. These are both very compact and provide easy data export after flight.

The internal structure of the avionics bay went through many iterations but the final version is a 3D printed PLA "sled" which the electronics and batteries are attached to. There is one in the coupler section which houses the Blue Raven altimeter and one inside the nose cone which houses the Featherweight GPS.

There were three series of testing I performed before each launch of Hi-Vis. 

The first is a test of all the electronics in their flight configuration. By following the flight integration procedure, I am able to workout any procedural issues and ensure the electronics will function as intended when I go to fly. I also tested the range of the GPS when inside the nose cone by placing the rocket on my lawn and driving down the street with my receiver until I lose signal.

The second test is the ejection, or "pop", tests. The purpose of these is to determine the adequate size of black powder charge to use so the parachutes will properly deploy. (These are the most exciting tests for sure)

The final test I perform before each launch is a full integration test the night before launch. This includes performing all the integration tasks up to assembling and installing the motor. It's mostly for finding any errors in my checklist and setting aside all the tools and equipment I'll need to bring with me to the launch site.

I attributed the partial failure of flight 1 to a poorly packed main parachute and inadequately sized black powder charges. I also decided to alter the design of the free-floating black powder charges to increase packing pressure of the powder and decrease the risk of leaks.