Auriga High-Mach Workhorse Project
Flysheet
Contact Information
Name: Ben Graham
RHIT Email: grahambd@rose-hulman.edu
Permanent Email: greatmaharg@gmail.com
Basic vehicle specifications
Length: 52 in
Diameter: 3 in
Estimated mass: 5.31 lb without motor
Motor selection: K600WH, compatible with high H through low L motors
Estimated apogee: 12000ft (standard profile), 16500ft (maximum)
Vehicle Design
Goals of design
The goal of this design is to create a reliable, fast-turnaround vehicle capable of exceeding Mach 1 for primary use as an electronics testbed. This vehicle is designed to fulfill two test cases that are not easily achieved with the current Rose Rocketry fleet: mach transition and accelerometer overload. Currently, these conditions are only achievable with small, space-constrained vehicles, which limits ability to prototype designs as well as compromising reliability since many of these vehicles are not capable of fitting redundant altimeters. This vehicle would be designed to carry two deployment altimeters as well as a GPS transmitter and an electronic payload in excess of Mach 1.
Proposed design with technical drawings/diagrams
Overall dimensions
The proposed design is a 3” fiberglass rocket with 54mm motor mount. This size was selected to make use of parts left over from the original 10K project and to allow use of leftover K600 motors from this year’s competition.
The primary dimensions of the vehicle are as follows:
Dimensions were chosen based on parts availability and motor fitment; this design allows up to a Pro54-6XL or RMS 54-2800 case while using exactly 36” of airframe tube and existing couplers and nose cones. The booster section has a total disassembled length of approximately 35”, which allows it to be transported in standard 36” shipping boxes for ease of transport and handling. The design also incorporates a tailcone AeroPack retainer; this significantly reduces the rocket’s base drag, increasing altitude range by approximately 10%.
Points of separation
The proposed design uses a head-end deployment configuration for its recovery system. In this layout, the main parachute is located in the nose cone, with the avionics bay forming the nose cone coupler:
Fin shape, cross-section, and thickness
The design uses trapezoidal ⅛” fiberglass fins with the following dimensions in inches:
The fins are conventionally attached through-the-wall to the motor mount. Based on Gabriel Woller’s MATLAB calculations and a shear modulus of 800 ksi, these fins have a flutter speed of approximately Mach 2 at 20,000 ft, outside the performance achieved by any motor that can physically be installed in the vehicle.
Estimated component masses
The predicted dry mass distribution of the vehicle is as follows:
Vehicle: 5.31 lb
Nose and recovery section: 2.86 lb total
Nose cone: 0.52 lb
Recovery hardware: estimated 1 lb (includes main chute + all cords, rough estimate)
Switch band: 0.07 lb
Avbay coupler: 0.27 lb
Avbay internals: estimated 1 lb
Booster section: 1.37 lb total
Drogue parachute: 0.1 lb
Airframe: 1.19 lb
Motor mount: 0.3 lb
Fins: 0.57 lb
Centering rings: 0.03 lb x 3
Epoxy: 0.2 lb
Tailcone: 0.18 lb
Simulations of estimated altitude and stability margin
Estimated altitude and stability were determined primarily through OpenRocket simulation, with backup simulations performed through RASAero to ensure accuracy at supersonic speeds. Center of pressure, plotted against mach number, was calculated as follows using the above programs respectively:
Both simulations show the vehicle’s center of pressure as no further forward than 36 inches from the nose tip at any point in the flight. With a maximum CG location of 32.1 inches, this results in a minimum of 1.3 calibers of stability throughout any possible flight profile;while the vehicle is not classified as a long rocket by accepted rules of thumb at a fineness ratio of 16.8:1, the stability margin achieved additionally satisfies the 8% length rule for long-rocket stability.
Estimated altitude for the standard K600 flight configuration was calculated in the two programs respectively as follows:
RASAero predicts the vehicle’s altitude significantly higher, at over 14,000 ft as opposed to just under 13,000 ft predicted by OpenRocket; however, neither flight simulation shows any anomalous behavior, and both predicted altitudes are within the 16,000 ft ceiling afforded by Indiana Rocketry Inc. Initial characterization flights will be used to further improve the accuracy of these simulations.
Materials and construction methods used
The vehicle will be constructed using traditional fiberglass construction throughout, with marine epoxy used for all structural adhesive joints. Fiberglass was chosen for its ruggedness and reliability; despite the team’s access to a carbon-fiber manufacturing sponsor, carbon fiber was rejected due to its opacity to RF signals, as any GPS tracking solution must be located in the nose cone coupler due to the location of the main parachute in the nose cone. GPS reception would be partially or entirely obscured by a carbon airframe.
The avionics bay will be constructed using a traditional threaded-rod structure with 3D-printed electronics mounting. This is a highly proven design, having been used on numerous past projects, and is extremely rugged and reliable while being easy to service and space-efficient. Some concern of RF incompatibility is raised by the presence of threaded rods near the GPS receiver; however, this risk was considered worthwhile considering the efficiency and reliability advantages of a threaded-rod design.
Configuration of recovery system
The recovery system of the vehicle will be configured as head-end deployment, similar to the design featured in [1]. The main parachute will be packed in the nose cone, with the shock cord tethered to the nose cone tip, and all electronics and payload will be located in an extended nose-cone coupler, with separation occurring on either side of the coupler. The drogue will be conventionally packed in the booster airframe, allowing motor backup to be used when flight profile allows.
The main parachute used will be a 32” or 40” elliptical parachute from rocketry shared stock, selected based on as-configured mass; the drogue parachute may use either a 12” elliptical, 18” x-form, or 24” elliptical chute depending on desired descent profile. The 12” elliptical parachute will be the primary option due to its improved ruggedness and relatively low packing volume.
Flight control will be handled by the de-facto standard configuration of an RRC3 as main altimeter and EasyMini as backup, with GPS tracking provided by an Eggfinder tracker. 2S LiPo batteries will be used to power the altimeters, with Fingertech Mini Switches used to enable them. Additional switches will be built into the avionics bay for use with onboard electronics.
Project plan
Table of costs and suppliers
Projected material costs for the project (not including scrap materials) are as follows:
Item | Vendor | Price | Supplies cost |
Totals |
| $53.00 | $96.69 |
3ft x 3" tube | Wildman | $0.00 | $67.69 |
Aeropack tailcone | Wildman | $53.00 | $0.00 |
Fingertech switches (4) | CSRocketry | $0.00 | $28.00 |
PETG filament |
|
| $1.00 |
Tools and shared hardware needed
The project can be completed entirely using tools and hardware available in the rocketry workspace. Shared flight hardware required are as follows:
EasyMini altimeter
RRC3 altimeter
Eggfinder GPS
2S LiPo battery (3)
Recon 40” parachute
Rocketman 12” parachute
Onebadhawk ¼” harness set
900 lb quick links
Pro54 hardware set
Workspace tools required are as follows:
Marine epoxy
Silica filler
Cordless drill and bits
Shop bench tools
Fin bevel guides
Project timeline and target launch date
The planned timeline for this project is as follows:
Fall 23-24 Week 5: Proposal submitted
Fall 23-24 Weeks 6-7: CAD design and avbay layout, parts fabrication
Fall 22-23 Weeks 8-9: Assembly and ground testing
Fall 22-23 Week 10: First flight
References
[1] Rocket Vlogs: “Head-End Dual Deployment Explained | High Power Rocketry Basic HED Packing Tutorial (How I do it).” Dec 20, 2022. Head-End Dual Deployment Explained | High Power Rocketry Basic HED Packing Tutorial (How I do it) .