I have some rather detailed thoughts about why we, as a nation and as a planet, have not developed safe, sustainable, routine, and reliable access to space (S2R2), and I plan to elaborate more fully on this in blog post. For now, let me summarize by saying that I believe that S2R2 access to space is an innovation problem, not an engineering one, and as such we need to apply the lessons of innovators more that the lessons taught in engineering schools around the country.
When I think of innovators, I think of the Wright Brothers, Wernher von Braun, and Thomas Edison to name a few. One common thread to all of these innovators’ work was the shear number of tests that they conducted. It helps if those tests are not all full up systems, but are simpler representations that allow for rapid and low cost iteration on ideas and design concepts. The Wrights for instance, built a number of kites and later gliders, before building the first airplane in 1903. The kites and gliders taught them valuable lessons, including that the then state of the art airfoil data was not accurate enough to base the design of an airplane on.
I propose that Mach 30 needs to follow a similar path, and build, fly, and test “kites” of its own to learn about what makes a good S2R2 launch vehicle. I will follow this post with some thoughts on guiding principles for a “kite” program that can directly benefit the Aurora Program.
A Mach 30 Kite Program should integrate into the existing Aurora Program. Ideally, we would use the Aurora Phase 1 Design Competition to solicit design concepts to test out with kite-level technology, iterating and testing until we learned enough about S2R2 space access to do design refinement and move to the next level of development. The catch is that it is not obvious what the appropriate level of complexity represents “kites” in the S2R2 design space. So, we really have an additional challenge on our hands, namely learning how to build this new kind of “kite”.
To overcome this challenge, I recommend the following integrated road map for Aurora and Kite development (note, indicated years are notional).
- Get ready for Aurora
- Complete planning for Aurora Phase I Design Competition (2010)
- Develop Kite Building and Testing Infrastructure (2010-2011)
- Aurora Phase I Design Competition (2011)
- Test promising Aurora Design Concepts using “kites”, emphasis on first stage concepts (2011-2012)
- Develop example Aurora first stage(s) to be used as launch platform for second stage kites (2012-2013)
- Refine Aurora stage 2 concepts and test promising concepts using “kites” (2013-2014)
- Develop example Aurora second stage(s) and demo single seat S2R2 access to space (2014-205)
There are some assumptions as to the nature of Aurora that feed this road map. These assumptions should not be taken as requirements, they are meant to inform the development of the Kite Program. They include:
- Aurora will likely be a 2-stage to orbit system
- Both stages of Aurora will be powered by rocket engines (no air breathing technology in Aurora)
- Aurora will likely launch vertically (though the kite program should include the ability to compare vertical and horizontal launch)
- Aurora will likely land horizontally
As I have pondered the development of kites (especially first stage kites), I have imagined a tiered approach to evolving their capabilities in order to learn what level of investment (material cost and time) is necessary to properly test Aurora design concepts. The tiers might look something like this:
- $200 kite
- Estes and electric R/C airplane components
- Could test basic flight stability
- Could be basic trainer for test pilots to give them experience across launch, climb, burn out, and return to launch site
- Could likely be flown several times per day
- $2000 kite
- N or O class model rocket engine, extended range R/C airplane controls and higher end components
- Could carry larger amount of instrumentation
- Could test telemetry and long range flight
- Extend envelope of flights (higher altitude, greater speed)
- Could likely be flown several times per day
- liquid rocket engine (LOX/Ethanol?), small scale UAV style controls?
- Could test representative speeds?
- Could test near representative altitudes?
- Could test representative trajectories (up and back)?
- Could develop full system materials handling and flight prep/maintenance
- Could test feasability of UAV controls for first stage of Aurora
- Could get sizing data for S2R2 class first stage vehicles
The 2010-2011 Kite Program would then focus on testing the capabilities at each of these tiers and developing the necessary infrastructure to build and test vehicles like these. The design should probably be derived from a historical example of a Mach 3-5 aircraft, and not focus on what a first stage for Aurora might look like. That can wait until after the phsae I design competition.