> Just popping up to near (sub) orbital *altitude* as Rutan's craft did is a
> much easier (and a MUCH less valuable) trick- it only gets to something
> like
> 4,000km/h, almost _two orders of magnitude_ less kinetic energy than you'd
> need to actually get into orbit (energy is proportional to the square of
> velocity). And you have to take all that extra fuel to accelerate the rest
> of the fuel you need to get to that speed! The potential energy is
> negligible by comparison.

I wonder how much less valuable.  Obviously if you want to put up a communications satellite Rutan's craft is woefully inadequate.  But if you want to get from one place on the Earth to another, and do it quick, what better place to do it than above the atmosphere?  

Do we think that a Rutan-inspired commercial trans-atmoshperic vehicle will really be practical for hopping between continents anytime in the foreseeable future?  Or will it just be the province of rich space tourists?

The promise of two hours to anywhere on the planet sounds great - until you remember the SST that failed to capture even the transatlantic business.  



-- Lawrence Lile, P.E.
Electrical and Electronic Solutions
Project Solutions Companies
www.projsolco.com
> -----Original Message-----
> From: Spehro Pefhany [mailto:speff@interlog.com]
> Sent: Thursday, December 09, 2004 1:15 PM
> To: Microcontroller discussion list - Public.
> Subject: RE: [OT] Yet another space program
> 
> At 11:25 AM 12/9/2004 -0600, you wrote:
> 
> 
> >Most of the power required to get into orbit is wasted getting up to the
> >top of the atmosphere - you have to shove the air out of the way, and lug
> >along a big rocket.  Why not float up as high as you can and launch from
> >there? Careful that the afterburners don't toast your balloon fabric
> though!
> 
> You have to achieve orbital velocity too (something like 27,000 km/h).
> 
> Just popping up to near (sub) orbital *altitude* as Rutan's craft did is a
> much easier (and a MUCH less valuable) trick- it only gets to something
> like
> 4,000km/h, almost _two orders of magnitude_ less kinetic energy than you'd
> need to actually get into orbit (energy is proportional to the square of
> velocity). And you have to take all that extra fuel to accelerate the rest
> of the fuel you need to get to that speed! The potential energy is
> negligible by comparison.
> 
> Best regards,
> 
> Spehro Pefhany --"it's the network..."            "The Journey is the
> reward"
> speff@interlog.com             Info for manufacturers:
> http://www.trexon.com
> Embedded software/hardware/analog  Info for designers:
> http://www.speff.com
> 
> 
> 
> 
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