Re: Doubts on the X-Prize contenders
This is certainly something to be concerned about, but don't you think
someone with the savvy of Burt Rutan hasn't already dealt with it? He's not
someone tinkering with model rockets in his back yard, you know. Let's give
him the benefit of the doubt.
And yes, no matter what happens, the publicity generated by the X-Prize can
do nothing but good for our efforts to get off the planet.
----- Original Message -----
From: "Adriano Autino" <adriano.autino@xxxxxx>
Cc: "Stephen Ashworth" <sa@xxxxxxxxxxxxxxxxxxxxx>
Sent: Wednesday, October 01, 2003 11:34 PM
Subject: Doubts on the X-Prize contenders
> Dear friends,
> this morning I got, from Stephen Ashwort (Space Age Associated), the
> hereafter referred, that -- for what I can understand (I am not a
> expert) -- expresses doubts about the concrete chances of the X-Prize
> to really make the targeted job.
> (also posted on http://www.tdf.it/cgi-bin/dcforum/DCForumID2/390.html )
> : *** To all associates of Space Age ***
> : Ross Sargent <rws.eighty@xxxxxxxxxxxxxx> has made the following comment.
> : Anyone else out there like to present a view on the technical problems
> : suborbital versus orbital flight?
> : Stephen
> : 1 October 2003
> : Stephen & Associates
> : May I take this opportunity to say that I hope my pessimism regarding
> : future orbital capabilities of the X-Prize contenders is misplaced -
> : one time I would love to be proved wrong. Your idea that orbital flight
> : be achieved in an incremental fashion seems, on the face of it, a
> : suggestion. It is the numbers that cause the problem - this is just off
> : top of my head but I am looking for detailed information - a comparison
> : the speeds involved and, by implication, engine and thermal protection
> : requirements is interesting.
> : The projected Spaceship One reentry speed given at Scaled Composites
> : ( http://www.scaled.com/projects/tierone/New_Index/body.htm ) is 2500
> : The reentry speed from Low Earth Orbit is 17500 mph or so - 7 times
> : faster - requiring a far more capable heatshield with the added weight
> : penalty this will incur. The mass margins for any spacecraft that is
> : even semi-reusable are very tight - obviously the more weight the bigger
> : engine required. Also in order to achieve orbital speed in the first
> : will require larger more efficient engines. In the case of Scaled they
> : opted for SpaceDev's hybrid motor and (you may be able to correct me
> : Starchaser are still yet to decide on either bi-propellant or hybrid
> : although both designs have been tested successfully. My concern is
> : these motors will scale up to the requirements for orbital velocity or
> : suitable for large scale clustering. The burn time, combustion chamber
> : pressure and regenerative cooling requirements are going to be far more
> : rigorous for orbital access. Jim Benson, boss of SpaceDev, described his
> : motor for Spaceship One as " almost directly suitable for the second
> : of SpaceDev's Streaker launch vehicle. That booster would be capable of
> : tossing 1,000 pounds (455 kilograms) of payload into low Earth orbit."
> : that this is as a second stage motor lofting a mere 455 kilos! Whether
> : can be a smooth upgrade path to orbital flight, no matter how well
> : space tourist rides, is something I still have trouble seeing. Note that
> : X-Prize stipulates a 100 km (62.5 miles) altitude flying a similar
> : trajectory to Alan Shepard's in a Mercury/Redstone combination - there
> : good long way to go when one considers that the ISS orbits at approx
> : km. (237/250 miles) - hence my slightly disparaging term "suborbital
> : I am an ardent proponent of manned spaceflight and find the prospect of
> : actual launches by the various X-Prize teams thrilling, but there is a
> : more engineering needed to cope with the altogether more demanding
> : requirements. As I said at the start I hope to be proved wrong - so
> : look at some more figures in my role of reluctant devil's advocate will
> : someone please comprehensively refute my pessimistic outlook?
> : By the way I agree completely that those of us in the UK should support
> : Starchaser's efforts - their chances of achieving any kind of crewed
> : spaceflight are a darn' sight better than this government's - or any of
> : their predecessors for that matter.
> : best wishes
> : Ross
> : Ross W Sargent
> : mailto:rws.eighty@xxxxxxxxxxxxxx
> : The View from Number 80
> : Skeptical Reviews
> : http://www.eighty.btinternet.co.uk
> : here is a Newsweek article on Rutan and the X-Prize, touting a possible
> : flight on Dec 17th.
> : http://www.msnbc.com/news/972359.asp?0dm=s12Bk
> : *************** S P A C E A G E ***************
> : http://www.astronist.demon.co.uk/saa00.html
> : *************************************************
> I thought it could be of some interest in this list, at least for the ones
> can give technical and/or economic opinions.
> Aim high!
> Adriano Autino
> Record your vision of the world in 2033! On the FUTURE FORUM!
> -- Adriano Autino
> Technologies of the Frontier
> web: www.tdf.it - e-mail: adriano.autino@xxxxxx
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