I got a lot of email on last week's Fox News column on how we don't need no stinkin' scramjets. It was interesting--the first few I got were favorable, then I got a lot of argument later in the day and through the weekend. First, to deal with the complimentary ones, since they're easy. The following several emails appear in order of receipt.

I enjoyed your article "Rockets Are Good Enough", and agree that the Australians are to be complimented on such fine work. The magnitude of this accomplishment is second only to the magnitude of NASA's ineptitude to do the same.

A dozen or so university students and faculty beat the pants off this nation's top scientists with millions at their disposal. As I last recall, NASA's most recent scramjet attempt failed miserably as it crashed into the pacific.

Perhaps congress should spend a little less time worrying what Martha Stewart does with her money and a little more time evaluating how federal agencies spend theirs.

Timothy Peterson
Houston, TX

In your last article, "Rockets Are Good Enough" you were absolutely correct.

A rocket is a very simple machine, payload, a body, two tanks; one for oxidizer and one for fuel, a turbo pump, guidance system, and an engine. A solid fueled rocket is even simpler. Ironic as it would seem, the aerospace industry needs to stop treating space flight as such "rocket science". In truth, most of our obstacles to cheaper and more efficient access to space are not technical, but bureaucratic and political.

While there is some progress in this direction, we need a serious effort to make the most reliable, powerful, and standardized booster vehicle possible. Even if this means there is wasted payload capacity each flight, the savings from a mass produced launch vehicle, and a high turnaround launch schedule will more than make up for it.

For my own sanity, I try very hard not to remember that the entire Apollo project was run on less computing power than a fraction of a painfully obsolete 1980's home PC, not to mention all of our other advancements in automation, fabrication, and materials science since then. The current state of space exploration and exploitation of it's infinite resources is truly disheartening, and there are no good excuses for it.

Andrew Walkowiak

That was a good article. An engineer myself, I'm constantly having to explain to my non-scientific and sometimes pseudo-scientific friends the differences between real science and hype. That was one I never really took the time to research. Thanks.

Keep writing.

Scott Weber
Mechanical Engineer

Just read the above article on Fox. Very lucid and convincing arguments. I'm sold. keep up the good work.

thanks

Pat Graham

I just read your latest article on the Fox website. Great stuff! I followed the link to your website and found even more great stuff. How refreshing it is to find someone who truly speaks his mind (and has something intelligent to say) without worrying about being PC.

I was wondering if you had considered doing a series of articles on the technical merits of the various (and numerous) private attempts to develop tourist class space vehicles? I'm very interested to know how feasible these efforts are. Hell, maybe you already have and they're on your website somewhere, but I'm too damn lazy to look through all that stuff to find 'em. Besides I have to go make another drink. :-)

Very Best Regards,
Chuck Rushing
Abu Dhabi

Abu Dhabi, eh? Be careful out there. And have a drink for me. Just don't let the Morality Police catch you.

I do occasionally write about prospects for various companies, but I've never done it in any organized manner. I'm picking away at a book, and I may do it there, though such things quickly become outdated as events unfold and new players emerge.

Now, on to the criticism. My comments will be either out of the blockquote, or inside the blockquote, in square brackets.

That's the reason, people want to develop scramjets. Less weight in oxidizer means more weight for payload. Just because the first developmental engines don't work well doesn't mean there is no merit in pursuing them.

Richard Mays

Well, no Richard, not really. Taking out structural weight pays off one to one for payload, but not oxidizer weight, because most of the oxidizer isn't taken all the way to orbit, so it doesn't have to be accelerated the whole way, as a payload must be. Depending on the vehicle design, in order to pick up a pound of payload, you might have to reduce anywhere from three to ten pounds of oxidizer (rough numbers, not based on any recent calculation). And I didn't say that there's no merit in pursuing them--just that we can get cheap space launch without them.

I both agree and disagree with your recent article. I agree with your thesis that the fuel cost is minimal for most launches compared to the overall cost. What I think you may have missed is (1) The biggest cost is probably the supporting human personnel cost associated with each launch, and (2) Where a hypersonic launch vehicle can be more efficient is where the lift necessary to get the payload into the upper atmosphere is generated by aerodynamic lift from a wing rather than by direct engine thrust. With respect to item (1), it is certainly true that a lot of the personnel cost per launch would be reduced with a higher launch rate. A greater saving would accrue if the government bureaucracy were less involved and private corporations were free to take whatever risks they could convince their insurers to carry. With respect to item (2) I spent some time associated with an air launch ballistic missile program called Skybolt. It was known even then that such a small missile as Skybolt (roughly 40' x 2') had the capability of achieving orbit with a supersonic first stage, such as a B-58. Unfortunately, all we had was the B-52. It seems reasonable that a flyback hypersonic first stage could be very effective in reducing the cost of getting a payload above 90% of the earth's atmosphere and up to a significant fraction of orbital velocity, the most challenging part of any launch.

Sincerely,
John F. Harvell

While it's true that wings have some benefit in providing lift, again, this is over a very small portion of the ascent trajectory. If you're spending enough time in the atmosphere in which this is significant to ascent performance, you're probably spending too much time in the atmosphere, because of all the drag it implies. It's not enough to increase effective propellant economy with these airbreathing/supporting tricks, if you increase the total effective velocity required as well, due to drag and heating.

You are quite right in saying that the fuel/oxidizer costs are paltry compared to the ops costs, and airbreathing will not reduce those costs. However by using Scram, that (ops costs) is exactly what we hope to reduce eventually by airbreathing. SSTO Rockets are quite heavy for vertical options and cannot even be done with HTHL option, being > 3-4M lbs weight if not more, since the landing/takeoff gear and runway requirements will not permit that. Airbreather/rockets (some form of RBCC) can close at about 1M lbs GTOW viz. the Inward turning option. This allows the option of horizontal takeoff and landing - not at all available for all rocket option.

This means that the present infrastructure of large airports, ATC systems etc MAY become available for this option. This can reduce the ops costs significantly, making it more palatable for people travel even. These types of things are the only ones that can make for a cheap access-to-space. The point is that with the all rocket option, we will NEVER be able to reduce the costs. With RBCC option, we at least have a definite possibility, and path to get there! If I had a choice between what cannot be done and something that could possibly be done, what should I possibly choose?! It opens up a plethora of options that we as a country ought to pursue. Attached pdf file discusses some of this and more in some detail.

Dr. Ajay Kothari
President
Astrox Corp.

Dr. Kothari lost me when he brought up SSTO, which I never mentioned in my article, and of which I am not, at least for this generation of space transports, a proponent. So he's attacking a strawman.

But just in case that wasn't enough, he said, with great emphasis, that there's no way for rockets to reduce costs. That's simply nonsense. He sent me a PDF file, ostensibly of a parametric study, that would prove this. Having done a number of such studies myself, I know that it's possible to prove just about anything you want with them. It depends entirely on the assumptions that go into them. I told him this, using the old phrase, "garbage in, garbage out." He took great umbrage.

You're logic is based on a faulty calculation. Not carrying oxidizer doesn't just double your payload. [Note: I never claimed that it did] It exponentially increases your payload. It also eliminates the need for structure to carry the oxidizer. Your vehicle is smaller -- a _lot_ smaller. Your payload is bigger -- a _lot_ bigger. The difference between transportation by horse and transportation by automobile is about the same as the difference between rockets and scramjets. The quantitative difference in scale yields a qualitative difference in the solution. Every pound of fuel and oxidizer needs even more fuel and oxider to accelerate it to where you need it. This is called the rocket equation. Basically, there is an exponential relationship between payload and the amount of fuel and oxidizer needed to get the payload into orbit. This means a scramjet doesn't carry just twice as much payload. Think more on the order of 8 times the payload. When you don't carry oxidizer, you also don't carry the fuel to accelerate the oxidizer. (The numbers: best rocket 5.3 km/s specific impulse, scramjet 40 km/s). [Only while it's in the atmosphere, and by having to stay so long in the atmosphere, the effective delta V required to get into orbit goes way up due to drag. And if you get high enough where that's not a problem there's no much oxygen, so you're back to the rocket problem. We studied this problem extensively during the NASP program, believe me.]

Most of the energy getting to orbit is used for velocity, not altitude. It makes sense to get your speed where you can get your oxidizer for free [But it's not free. You have a severe drag penalty, and performance penalties from off-design conditions. That's the myth of the airbreathing set, that collecting oxygen is "free." It's like the "too cheap to meter" story that they used to tell about nuclear plants.] -- and where you get oxidizer for free, you also get lift. Lift adds even more payload. The little Pegasus booster gets about a fifth of its payload capacity from its wings. The limiting factor, of course, is drag. When its first stage burns out, the wings on Pegasus are charring.

Scramjets also get a little thrust advantage from Venturi magic, just like the U.S. Air Force's SR-71. The SR-71's engines are pretty close to being ramjets. They get the major part of their exhaust velocity from the Venturi effect on the ram air -- not from the fuel burn.

Rockets are tough to compete against. Non-NASA rockets are cheap. In the late 1970's TRW demonstrated a kerosene/lox engine with a million pounds of thrust, with a cost-to-build tag of $40K (that's right -- thousand). Scramjets, though, are even cheaper. Scramjets have no moving parts (except for maybe a movable inlet spike at the front). The only way to get any cheaper is with solid propellant, which has its own set of problems. The net result is that scramjets may be the enabling technology that will allow aircraft to depart from commercial airports and fly into orbit.

For 40 years of experimentation, scramjets have been "scamjets made of wishalloy mixed with unobtanium". The Australians have broken that dictum and performed alchemy to achieve a frustrating, difficult, and long denied goal. Sure, maybe other minor research examples (such as a Russian anti-ballistic missile warhead) may have been done -- but the Australians did in public with media announcements where we can all look at it and criticize.


Glen Dayton dayton@ieee.org

I replied:

Exactly my point. There may come a time that airbreathers are cheaper than rockets, but that time's a long way off, and to defer a decision to build a low-cost space transport while waiting for chimeric new propulsion systems would be a tragic mistake.

To which he responded:

True. We can build reliable and cheap rockets because we've doing a long time. Scramjets still suffer from being an infant technology with demonstrations still on the order of non-repeatable stunts. But a long way off? Economic pay-off and NASA non-involvement will determine the rate of implementation. How far are we from strapping a scramjet on the side of Atlas or Delta for thrust augmentation?

[A long way. Boeing and Lockmart are notoriously conservative when it comes to adding radical new technologies to their expendables]

The Australian effort may turn out to be a flash in the pan. We haven't seen any numbers on ablation, for example. As for air breathing, there may be still more than one way to solve that problem. Did NASP take into account ram thrust? The SR-71 flies fine, and from my estimates, a lot higher and faster than announced (you do hear stories about it out-running a Mach-5 missile, and rumors of refueling it with drogues dropped from the space shuttle). As the technology develops I really expect air breathing flight above 200,000 feet (but my expectations are at this time unfounded without engineering data to back them up -- your NASP experience probably gives you the real numbers).

My own experience, though, is that NASA has actively discouraged, and still discourages non-rocket propulsion and anything not involved with vertical launch. NASA pressured the government to shut down the X15 so it would not compete with vertical launch. Several times in my own career, NASA has shut down independent research projects on cheap alternatives with the threat we would not get any future contracts if we pursued that product line. This is why even though TRW demonstrated a million pound thrust engine, that was repeatily fired, for $40,000; they are not in the cheap rocket engine business. NASA purposely delayed commercial licenses for Delta and Atlas to squash competition for the space shuttle.

I worked on the shuttle safety studies for the Inertial Upper Stage flight. I am still angry that most of the data NASA supplied me on shuttle recovery modes were bogus. In other words, to me, NASA means big, conventional, and without credibility. I don't mean disrespect to you and your involvement with NASP -- but it does mean you have to work harder to prove your point.

I appreciate your response to me. It was educational. I don't really want to take more of your time, but I hope some of my comments may serve as grist for a future column.

Glenn Dayton

They may. And I agree that the fact that NASP was a failure does not, in itself, constitute evidence that scramjets can't work, or be cost effective, any more than the X-33 debacle provides any useful insight as to the viability of SSTO in general. However, a lot was learned in the course of the program that indicates that their promise is less than that of their most enthusiastic proponents.

Another bit of applause...

Hi Rand, Just wanted to let you know I thought your article (Rockets Are Good Enough) was short, sweet and to the point. I'm a project manager with the National Space Society and at our meeting this month we were discussing this same issue. It seems that anybody with any logic realizes that hypersonics are a poor solution to most commercial space transportation ventures. I guess the government-industrial complex is still alive and well. The technocrats who make their living on government grants have found themselves yet another holy grail to pursue in the name of progress. Anyway, just wanted to let you know I think you're right on the money with this one. Best regards, Michael

This next, long analysis is from someone who apparently works for Airbus or a subcontractor in Europe.

While you present indeed interesting points, I think you miss some about the interest of not having to take oxydizer onboard prior to take-off.

Size of vehicle is paramount to a successful development that would lead to an actual prototype, since that's where we are at this time: nothing new has ever successfully flown. The aircraft industry has always said that a big aircraft is an expensive aircraft, particularly in the hi-tech arena such as fighter development: the most successful "modern" fighter sales was the F-16 so far, which indeed was the first aircraft to break the "faster, higher, furthern hence bigger" philosophy that culminated with the F-111 (I think they should have called this one B-111) and the F-15. Same is going to happen now: Very few countries could afford the buy the YF-22, hence the JSF, purposedly designed and produced, and bought in large numbers to kill the european fighter industry.

In the civilian business (I'm working the the A380 super-jumbo), size goes along with money provided you mainly take payload onboard (pax/cargo) rather than fuel! What will make the A380 successful isn't its sheer size, but its fuel economy per pound of thrust (very large turbofans are easier to be made economic rather than small ones such as williams' FJ-22s) , especially when divided by a large number of people. That's why Boeing is going to have great difficulties to make the sonic cruiser, if it ever succeeds. At the other end of the scale, I've flown general aviation aircraft here in France that weigh less than 300 kg, take twice as much load as current aircraft and cruise at nearly 180 knots with 100hp Rotax engines at less than 25l/hour fuel consumption (sorry, no idea about what it makes in imperial units) for nearly 5000 km, while so-called "new" cessnas, mooneys or pipers hardly fly above 150 knots, need at least 300 hp to do so, and weigh more than twice, due to old-technology airframes and the enormous fuel load they must carry (when you fly full fuel to go somewhere not too near, you can't take anyone onboard).

We need to think "small" for our ideas to become anything more than just ideas, and the same goes for space-business. Air-breathing is one way of making space-vehicles relatively "small"

Now the point I want to make is that a couple of years ago was designed the most clever concept for years by Mitchell Burnside Clapp and fellows : the Black Horse pure-rocket plane (orbit capable), which later evolved into the Pathfinder suborbital launcher. The Idea of "aerial transfer propellant" (in-flight re-oxydizing rather than refueling) was a very clever one : while it is true that oxydizer (either LOX or H202) are cheap and dense, and therefore do not contribute to such an increase in flight vehicle size or operational costs, they are indeed HEAVY, much heavier than low-density H2 or CH4, so when used in HTOL configurations, landing gears, wing size must be greatly increased, and therefore unfavorable snow-ball effect inevitably lead to big, expensive vehicles. Just compare the size of the X-33 and the Black-Horse: about 2 or 3 times bigger . I bet you an operational space-plane patterned after the black horse could have flown at a fraction of the X-33 cost !

The rationale behind the design of pure rocket-planes and air-breathing space-planes are fundamentally different : As far as I can remember, rocket equations dictate that the structure of the vehicle be as light as possible while taking onboard as much fuel and oxydizer as possible, leaving marginal payload capabilities: you build a space-borne supertanker. In air-breathing spaceplanes, you put mass into the structure, scramjets etc, while trying to minimize the amount of fuel and oxydizer (if any) to take onboard.

The interest of scramjet-powered vehicles lies in operational flexibility: carrying aloft large quantities of high-energy propellants isn't a good idea, and what you want ultimately is airliner-like operations (including horizontal take-off and powered-landings to integrate standard air traffic). The challenge is much greater in scramjet technology (catastrophic unstarts, off-design flight conditions..), and I think it's true pure-rocket is the most straightforward thing to go for in the 2nd generation RLV effort , but in every case you should focus in making the orbital vehicle the smallest possible, either by sub/super/hypersonic air-collection , aerial propellant transfer, two-stage to orbit (airliner-like 1st stage) or any other scheme that would make the orbiter as simple as possible. The ideal to me would be a "JAR-FAR25 certified" (or almost) first stage with lots of redundancy to ensure Airliner-like operations, carrying a pure rocketplane/expendable performance-oriented second stage with less design margin.

Ultimately things such as plasma aerodynamics and MHD control offer the prospect of a total hypersonic flow control, ensuring permanent on-design ramjet/scramjet operations. So, while pure rocket RLVs are the best near-term solution, either for earth/mars/moon to their respective orbit transportation, airbreathing-engine technology IS the way forward for routine earth-to-orbit transportation, it's only a long-way off and a fascinating subject !

I actually agree with almost all of this post (though I'm a little skeptical about the MHD (I assume he means magneto-hydrodynamics) control stuff. When it comes to launch vehicles, small is indeed beautiful, but in the near term, I think that the most cost effective way to get there is by downsizing payloads, not by pushing the technology envelope. And Mitchell Burnside-Clapp's idea of in-flight refueling (well, in flight re-oxidizing...) is an interesting one (as is Kelly Space and Technologies towing concept), and well worth looking at. I hope that Pioneer can eventually raise the funds to try it.

The next one is from someone at NASA, but I don't want to give his exact affiliation, lest he be thought to be speaking for the agency. I assume that he does not, in this case.

Excellent assessment! ("Rockets are Good Enough", 8/22/02). Now take on a REALLY controversial issue - will high degrees of reusability translate to lower launch costs? Back in the days when the rocket engines were 50% of the launch vehicle production costs, that argument might have made sense.

However, the technology of (relatively) inexpensive engine production combined with the high cost of bringing them back to earth (wings, tail, landing gear, thermal protection, etc., etc) and recertifiying them certainly makes that an open question.

I responded via email thusly:

Well, as long as they have to be "recertified" every flight, they'll certainly never reduce costs. But if we just refly them like airplanes, and fly them a lot, they will. The "high costs" of bringing them back are due almost entirely to the low flight frequency. At current flight rates, expendables make sense. Of course, at current flight rates, *no* technology or vehicle deisgn will get the cost down to anything reasonable.

Shuttle has nothing to teach us about how to operate a space transport, at least not in any positive sense. It provides an excellent example, however, of how *not* to do things...

I agree that the main determinant of launch costs is launch frequency. However, this is the main problem with current rockets; they are expendable, not reusable. (The Space Shuttle, IMHO, is a special case that ingeniously combines the worst of both worlds...). If launch frequency is to be increased with current rockets there is no alternative but to increase production rates, which itself is an expensive and long-lead-time exercise. It is too much of a commercial risk to do this up front.

A reusable system has the advantage that it can respond to increases in demand *by more frequent flights of the same vehicle*. Ie it would be much easier and cheaper to experiment with a more intense launch schedule and see how the sums came out.

I know about the DC/X and that many of the X-Prize contenders are proposing reusable rockets. However, most fully reusable concepts envisage an air-breathing airframe using (say) scramjet/PDE/ODWE/LACE etc which, fuel
apart, could use more conventional infrastructure. In the case of a scramjet, the final boost into orbit would only require a simple and cheap (probably solid fuel) "kicker" stage.

[I don't believe that solid rockets have any role in a routine space transport. There's no reason that liquids can't be made sufficiently low cost and reliable, and their flexibility (e.g., you can throttle them in real time, and shut them down, and restart) will more than compensate for any extra cost that might be incurred. In fact, I'll be heretical and say that liquids will likely be much cheaper than solids, at high flight rates--ed]

Re. the Australian scramjet test. Last week I attended a fascinating lecture at the National Museum of Australia given by Dr Allan Paull, head of the University of Queensland Hyshot project (and who before that spent three years at NASA, mainly at Langley). I asked him afterwards re. claims that scramjets are unsuitable for acceleration missions such as launching satellites (you're by no means the only person to make this claim) and he said emphatically that according to their research this is *not* the case and that use as a launch vehicle is one of their main target applications.

[I'd like to see that research. I have trouble buying it.]

A major criticism (rightly) made of scramjets has been the need for flight testing to put some hard numbers behind CFD and wind tunnel studies. We now
at last have some; 8 seconds isn't much but it's an eternity compared to hypersonic wind tunnels or the US military 30 msec "flight" last year. He reckons it will take a couple of months to fully analyse the telemetry, but so far it looks in line with their wind tunnel results. So in a couple of months we should be on a firmer footing re. just what a scramjet can and cannot do.

Some other interesting points:

- someone asked about the difficulty of igniting supersonic flows, another theoretical minus for scramjets. He said something like "There's nothing difficult about it; we've just done it!"

[Just because he did it, doesn't mean that it isn't difficult. The statement is that it is difficult, not impossible...]

- he reckons a scramjet can go to Mach 12-15 before a final stage rocket takes over

- the fact that the scramjet in the Hyshot test did not develop net thrust was deliberate so that the speed of the vehicle would remain constant and hence not bring about additional control requirements (and I assume a constant speed makes the data at different altitudes more easily compared). (IIRC from earlier reading about Hyshot it was also designed to be geometrically simple to make it easy to build and make theoretical predictions for). He said that they could easily have made one that delivered net thrust and that's what they'll be looking into next.

What they've achieved for 0.5% of the budget of Hyper-X is remarkable.

cheers,

Malcolm Street

B.E. (Mech), Sydney University
Worked 1980-2 at British Aerospace Dynamics Group, UK, analysing missile
flight trials.

I do agree that the Aussies are to be commended, and I wish them the greatest success in their follow-on activities. I just don't want to hold up the development of affordable launch while we're waiting for their research to pan out. The next letter writer says that the Aussies weren't really the first.

In spite of what the Aussies might say, the Russians at the Central Institute of Aviation Motors (CIAM) were the first to fly scramjets beginning in 1992. True, the first couple, including one joint one with the French, operated in the ramjet mode at a max Mach of 5.0 to 5.5, but they were genuine scramjet designs flown at less than hypersonic speed. On the other hand, NASA had a joint project with the same Russians and successfully flew an improved scramjet configuration at Mach 6.5 (fully hypersonic) in Feb. 1998 ? some four years before the Australians. And, based on actual flight data and post-flight CFD analysis, CIAM claims they indeed achieved supersonic combustor flow (Mach 1.5) during the almost 70-sec. test phase at about 26 km. I know about this because I was the NASA Dryden project manager for that joint effort and recently retired. I know the Australian team well and they often set in on our AIAA presentations on the CIAM result, so I don?t know why they or anyone else would make such a claim for the HyShot flight given a lack of thorough data analysis and the highly dynamic ?downhill? trajectory they flew. The Russian test was at least semi-steady state at the top of the ballistic arch of the SA-5 booster.

By the way, I spent nine frustrating years on the X-30 NASP, worked the CIAM activity and created/started the X-43 Hyper-X project at NASA. So you can imagine I don?t agree with you on the ?stinkin? technology? view of scramjets. Part of that comes from my experience with the Shuttle which was suppose THE RLV solution back in the 60s/70s and has never panned out. So much for rockets. The 50 flight-per-year frequency, less that $5K/payload lb. transport cost, etc. never was realized on the Shuttle/rocket approach as you well know. On top of the high maintenance, low launch rate, high manpower for flight turnaround (thousands at KSC and four months time on average), etc., NASA still acknowledges it costs about $500M per launch ? the infrastructure being huge! That works out on average to around $20K/payload lb. which almost doubles the cost of the ISS itself just to haul components up on some 45 Shuttle flights (for the full, original ISS). You?re right in that airbreathing technology has a long way to go and the U.S. (DOD/NASA) have done a dreadfully wasteful job of pushing it over some 30+ years, but I still believe it?s achievable and provides cheaper space access in the future - which is why I tried so hard to get things like scramjets in flight after the demise of NASP. I still think $2K-4K/lb. payloads are possible if you not only carry less internal propellant load (admittantly just keying on oxidant is naive and overly simplistic) but fly much more often and with quicker turnaround times ? which rockets cannot and have not demonstrated! The Russians, Germans, Japanese and French reached that conclusion in their own SSTO or TSTO analysis studies based not only on much higher Isp, less propellant and other performance issues, but because of more airline-like simpler, lesser infrastructure required and much, much higher flight rates. You know ?one-shot? ELVs can?t do that (high cost per item, non-reusability, etc.) and rocket-powered RLV concepts like Shuttle haven?t shown it either. It?s got to be a much more routine operation with tens of ground crews instead of thousands.

- John Hicks
- Retired NASA Dryden

Gotta love that last paragraph. He manages to give us several of the prevailing industry myths in just a few sentences. I'll expand on this a little later today.

Holy crap, that was a long post.

Good bunch of responses. I say the jury's still out on what the cheapest (and above all, most profitable) methodology is for getting people and equipment into LEO. Paper studies are nice, demonstrations are nicer, but the real tale is in repeated flights. And what launch facilities and support equipment and personnel are used.

I have to agree that rocket science ain't what it used to be (and, you might add, it never was). But I'd like to discourage the idea that it's something that any idiot can do in his own garage. Like it or not, aerodynamics and flight control require some analysis and design. This requires some brains. Yes, this is easier than it used to be, but still requires knowledge of engineering and experience is a handy thing. It sounds like the XCOR rocket plane next phase is already benefitting from experience.

Good stuff, Rand.

>> But I'd like to discourage the idea that it's something that any idiot can do in his own garage.

Why?

If you want something to become popular, it has to be seen as something that normal people can do. When ordinary people see that even loonies can do something, they know that they can do it.

Yes, you end up with several dead barnstormers, but you also get a lot of people thinking "that's fun and I'd pay money to participate".

I think you misunderstand. Riding rockets is not what I spoke of. It's the designing, building and testing part. In any event, until piloting or design actually become something that "everyone can do", I'd just as soon they didn't. At least, not near where I'm sitting. There's enough idiots on the highways; idiots hurtling through the air is not something I'm all that comfortable with.

Both Perron and I are talking about design, fabrication, etc.

>> There's enough idiots on the highways; idiots hurtling through the air is not something I'm all that comfortable with.

The cure is worse than the disease, mostly because there is no disease. To put it another way, loonie rocketeers aren't dangerous.

(1) The vast majority are all talk.
(2) The vast majority that actually build something won't get off the ground.

NONE will make it far enough to do any damage to anyone who isn't on the launch platform or in the rocket.

Yes, there's a small risk to neighbors from folks who are mixing propellants in their garage. Call the fire department.

With both the car and airplane, "any fool" could try to build one, so ordinary folks felt comfortable buying and riding in them.

Regulations are govt's way of saying "this is too dangerous for ordinary people". Since the regulations can't protect anyone (the danger is non-existent), why do you want govt sending that message?

I'd say the cheapest way into space, would be to sink all the money required into a mission to go out into the asteroid belt find a asteroid mostly composed of uranium/platinum/gold/nickel/iron etc. Then bring it back to Earth and park it in a high but stable orbit. And let that stand as a symbol of how petty our notions of milions, billions or trillions of dollars are compared to the vast riches of the universe. Just think it would be a small asteroid that one could look up in to the sky with a small pair of binoculars and parents could tell their children about how man braved the perils of deep space to bring it back home for all the world to share. That would be the the only reason people would need to go into space then because the cost of anything becomes neg compared to whats to be hand for those who are inclined to look for it.

Rockets haven't demonstrated less than 4K/lb. to LEO eh? Don't tell that to the Russians.

Take a gander at this:

http://home.earthlink.net/~markreiff/projects/guest/radley.html

Rand:

You forget the entire Woomera experiment was actually motivated by the idea of ramming a rocket into the desert at mach 8.

An Earth-shattering kaboom! Hmmm?

A) A rocket that can achieve LEO is much more dangerous than a car.

B) Who said anything about government? That said, you have to pass some basic test of competency to acquire a driver's license. Somewhat more testing is required in order to transport large quantities of, say, liquid oxygen on the road. Isn't it logical to require some further testing in order to be able to drive a multi-ton vehicle capable of achieving velocities in excess of 7 km/sec?

sir,
I am a student of Mechanical Engineering (B.Sc.) and I have a project on "Phenomena of Mechanical erosion in heat shield charring ablators". sir i will be very thankful to you if you kindly sent me some litrature on that topic
which can express the phenomina in a simple way so that i could be able to calculate some parameters like temperature profile ablation rates charring depths.