This is a private project. It's not associated with any research institution or other for-profit company.
The platform will resemble a scaled-down Apollo command module. This basic configuration is stable through the supersonic and trans-sonic flight regimes that the HAPP will experience. Diameter of the base is approximately 1 meter.
The HAPP will utilize cold-gas reaction control jets and an autopilot function to enable stabilization. This is critical for obtaining smooth video footage. Disturbances can be expected from the atmosphere, from the natural motion of the balloon during ascent, and from motion induced by balloon rupture at apogee. A typical drone platform cannot be used, as there is almost no atmosphere at 30Km for drone propellers to grab onto and provide thrust. The development and utilization of a cold-gas reaction control system is unique and distinguishes this project from other peoples' attempts at high-altitude photography using weather balloons.
The stabilization is purely rotational and will not provide any lateral control. The HAPP cannot be "flown" in various directions, although it may be possible to control the glide during free fall to a very limited extent by commanding the jets to put the HAPP into an off-vertical position. The anticipated glide ratio is 0.4.
Downlink telemetry including GPS coordinates will be provided by satellite phone. The HAPP will not stream live 360 HD video; the video will be stored on-board and collected for post-processing.
|One of 12 nozzles for the cold gas|
reaction control system
Project timeline (past):
- 2015 Q4: Preliminary research.
- 2016 Q1: Modeling and simulation of flight dynamics and control system.
- 2016 Q2: Blog launched.
- Control software developed and implemented on Arduino hardware. This includes various sensors and an inertial measurement unit (IMU).
- Jet nozzles designed, 3D-printed, and validated through static and dynamic test firing.
- Pneumatic system finalized, including lightweight carbon fiber tank and solenoid valves.
- Trifilar pendulum constructed to obtain moment of inertia data. MOI data was used in dynamic test firing to determine actual (vs. predicted) jet force. Millisecond oscillation timing provided by angular rate data from the on-board IMU.
- Vacuum chamber constructed inside a standard 55-gallon steel drum to allow dynamic test firing with a rotating test platform in high-altitude conditions. Necessary to validate jet force as a function of ambient air pressure. Fire control provided by WiFi link from Arduino flight computer to a customized app on my iPhone.
- The vacuum chamber's top portal sits on the rim of the steel drum. The portal was constructed from 1.25" thick cast plexiglass. The plexiglass was routered and a custom silicon seal was poured into the channel and allowed to vulcanize at room temperature.
- The vacuum chamber steel drum (a.k.a. pressure vessel) was reinforced by a welded steel exoskeleton. This design was created after imploding the first drum with negative pressure.
- 2016 Q3:
- Flight hardware build commenced with carbon fiber internal structure machined by water jet and CNC milling.
- Built cradle for high pressure gas tanks using flexible, custom-molded expanding polyurethane beddings.
- 2016 Q4: Vacuum-molded the outer aero shell using kevlar/carbon fiber reinforced polymer.
- 2017 Q1:
- Final design and finite element analysis completed in CAD system (Fusion 360).
- Center of gravity adjusted for stable aerodynamics on descent.
- 360-degree camera cradle designed and machined.
- Parachute recovery system developed; initial design relied on ambient airflow to deploy chutes; final design uses active deployment with pyrotechnics.
- Started live testing of recovery system.
Project timeline (future):
- 2017 Q1: Complete flight hardware including aero shell and parachute recovery system with pyrotechnic deployment.
- 2017 Q2: Complete downlink telemetry hardware and software. Complete video capture system including camera(s).
- 2017 Q2: Initial flight testing and performance analysis.
- Summer 2017: First high-altitude attempt, possibly Southwestern United States.
All site contents (c) 2016 HAPP Research, LLC