Spacefaring America: Recent Comments

Comment on 16 - Mike Snead's talking points from his "The Space Show" appearance

2011-01-21T00:41:08Z

Unfortunately, history tells us that when human safety is involved with the routine operation of a new infrastructure requiring substantial investment, the government must take the lead. While many now cheer efforts by private industry to pursue suborbital commercial spaceflight, I do not agree that this will be a successful approach. One indicator is the need to require waivers to use the infrastructure. When was the last time you signed a waiver to ride an elevator or fly on a commercial airliner.

Comment on 24 - Space solar power and America's energy future (Part 5)

2010-11-30T08:39:12Z

I am truely interested in the part of why are all of the NRH reserves combined into one total, it gives a reasonable expalination.Thanks for sharing.

Comment on 16 - Mike Snead's talking points from his "The Space Show" appearance

2010-07-30T19:25:42Z

If the government decides not to fund or pursue space logistics, what are our options as private industry and/or pro-space organizations? It is scary that the government is our only hope for becoming space-faring (within our lifetimes).

Comment on 18 - Aerospaceplanes and Space Solar Power

2008-05-23T19:39:22Z

Mike: I generally agree with you, but have a different explanation of why industry has not acted on your ideas. I believe that "These are the primary reasons why achievable two-stage aerospaceplanes have not been pursued in the last quarter century." is not correct.

I believe it is a very deliberate business choice - why take the chance that "build it and they will come" will increase the market and, even if it does, they will have to fly far more often at much greater risk, with no more in net proceeds.

How do we beat this attitude is more challenging than design of the "best" vehicle.

Comment on 24 - Space solar power and America's energy future (Part 5)

2008-05-21T01:15:07Z

A deliberate and determined transfer of focus from arms manufacture to energy self suficiency would provide greater security to the nation and provide the funding.
Only those who will not see can still argue for non renewable energy sources.
A commitment to solar energy from space would promote national pride jobs and advances in technology as yet undreamed of.

Comment on 22 - Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

2008-04-04T01:49:33Z

Adrian,

There are many possible approaches to achieving a fully-reusable space access system. The problem is that is takes considerable engineering resources to transition ideas into a viable concept with defined and available technologies and critical subsystems.

Mike Snead

Comment on 22 - Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

2008-04-04T01:40:47Z

Adrian,

Thank you for commenting on the Space Review article. I would like to comment on the second point that you raised.

Adrian: "I also believe that the whole "airplane-like" efficiency thing needs to be wrestled down to reality. I don't think it's a good analogy primarily because the volume of air traffic is probably always going to be much higher than even a robust space-faring system, and always less technically challenging. It somehow implies that we could -- and need to have -- orbital craft that could take off from any airport, willy-nilly, and do so on an hourly basis. There is no such need, nor will serious exploitation of Space even require it. A very robust and lower-cost collection of launch systems could sustain a large and viable space-faring effort even if the vehicles have to take off (and perhaps land at) from a limited number of dedicated launch sites."

Response: A true spacefaring nation requires the ability of its citizens to be able to access space safely and routinely. We have two models of space transportation that can be pursued to achieve this goal. The first is an extension of today's expendable or partially-expendable space access systems. The second is an extension of current airplane operations. The difference between these two is not the mode of propulsion, but the design, engineering, and operations model. A comparison of the advances in safety, cost reduction, and operations since 1958, the start of both the jet age and the space age, are very telling. Commercial aircraft operations have advanced significantly in all areas. Space access has generally not advanced and, given current plans for the next generation of human space transportation being pursued by NASA, will not make any substantial improvement in safety, cost reduction, or operations for another generation.

Our need now is for a fully-reusable, two-stage space access system developed as an extension of airplane operations. This means that the design and operation of these systems will come through the application of the aircraft-style system engineering processes that have proven to be very successful in developing increasingly better air transportation while incorporating new and improving technologies. Achieving "airplane-like" efficiencies are a product of the successful application of these engineering processes. Such a capability can be achieved in ten years.

Mike Snead

Comment on 22 - Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

2008-04-03T16:48:14Z

I have a question:

Why not an interim ram-jet-based system? A rocket sled could build up enough speed for ramjets to start up, and, realistically, a ramjet flyback booster could get to MAC 4 or so before separation. The idea is as old as the Space Age (Wily Ley), and doesn't present the technical barriers that scramjets do. Also, the resulting speed and altitude should be enough to achieve orbit with a single, remaining, reusable rocket-powered orbiter stage. The flyback booster in this concept would be more compact than a rocket-based one, especially if the initial rocket phase comes from a sled that never leaves the ground.

The other option that crops up is the Air-Turbo Ramjet for fly-back boosters. Any merit to the claims that ATRs can achieve low hypersonic speeds from a dead start on the ground?

Please correct me if my assumptions are simplistic.

Comment on 22 - Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

2008-04-03T16:35:50Z

I never bought into the idea that a scramjet SSTO was the way to go. You did a very good job of summarizing the technical obstacles involved. Of course, I could be proven wrong by events, but I don't see it.

I also believe that the whole "airplane-like" efficiency thing needs to be wrestled down to reality. I don't think it's a good analogy primarily because the volume of air traffic is probably always going to be much higher than even a robust space-faring system, and always less technically challenging. It somehow implies that we could -- and need to have -- orbital craft that could take off from any airport, willy-nilly, and do so on an hourly basis. There is no such need, nor will serious exploitation of Space even require it. A very robust and lower-cost collection of launch systems could sustain a large and viable space-faring effort even if the vehicles have to take off (and perhaps land at) from a limited number of dedicated launch sites.

Comment on 22 - Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

2008-04-01T14:57:29Z

Mark,

Thank you for commenting on the article. I would like to respond to a couple of your points.

"The central piece to recent Air Force examinations of scram is two flavors of combined cycle: rocket-based (RBCC) & turbine-based (TBCC). Various combinations of these, including staging with scram (lower-stage scram only, upper-stage scram only, both stages scram) are the subject of numerous trade studies."

Response: I argue that any reusable space access system approach incorporating scramjet propulsion will share common design, testing, and airworthiness certification challenges such as those briefly discussed in my article. Trade studies are very helpful in deciding how best to focus science and technology funding for achieving necessary risk reduction. However, such trade studies, in my experience, focus on the ideal system design optimization and quite often do not address important engineering development, testing, and certificaiton issues such as I raised. An ideal design that cannot be practically built has limited merit.

"I agree with your thesis that scram isn't ready for prime time, but I'm concerned that the tone of your article may sour readers to the very real potential of the technology for the space-access after next."

Response: I support continued research into the fundamental science and technology for scramjet propulsion for reusable space access where this solution is shown, through trade studies, to provide signficiant safety, operational, and/or affordability advantages. The U.S. needs fully-reusable space access for passengers and cargo. Getting to orbit with acceptable safety, operability, and affordability are the primary considerations. How this is best accomplished is a systems engineering issue. For a second-generation reusable space access system to follow a first-generation TSTO, rocket-powered system, scramjet solutions should be considered. With a developing spacefaring logistics infrastructure, as I advocate, the need for such improved space access, especially for passengers, will develop about 2025-2030. This is the time period when a suitable scamjet-powered system could be used.

Mike Snead