posted 08-09-2005 07:00 AM               

WWBRD: one reader's answer
In light of challenges facing NASA's Space Shuttle program, BoingBoing recently asked the question, "what would Burt Rutan do?" Many wrote in with possible answers, but the golden jackhammer prize goes to reader Brady Hauth, who says:
Pungent greetings, indefatigable Xeni, Midas of vivacity!
The specific energy required to reach the altitude SpaceShipOne (SS1) reached is this, corresponding to this speed. Orbits are only stable above around 180 km. A 200 km orbit requires a speed of 7.78 km/s, so getting into a 200 km high orbit requires a specific energy of this, corresponding to this speed. That's 7.54159384 times faster! The formula for the speed of a rocket tells us that to go that much faster requires 693.390852 times as much rocket.

The exact cost of SS1 isn't public, but was probably between $20 and $50 million - I'll say $30 million here. Scaling this up to a low earth orbit capable rocket, we get $20.8 billion. I'm estimating the payload of SpaceShipOne at 400 kg from the rules. The shuttle launches 24,400 kg - 61 times as much. Scaling costs up to something that size, we get $1.2688 trillion The costs of the shuttle program over its entire life? About $145 billion.

Add in the costs of protecting the craft from re-entry from actual orbit, and things start to look expensive.

Now, one can get higher specific impulses than Rutan did, which reduces that number above the e. It makes for more expensive engines, but it doesn't have to cost nearly as much as it costs NASA. (Maybe they're paying people to make presentations like this one from the military?) One can argue that Rutan could make a design that could make orbit cheaply. However, his building SS1 is not good evidence of that. That is a completely different requirement requiring entirely different engineering. A much harder and much more expensive requirement.

posted 08-09-2005 11:13 AM            

quote:

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Originally posted by eurospace:
Highly interesting .....
The specific energy required to reach the altitude SpaceShipOne (SS1) reached is this, corresponding to this speed. Orbits are only stable above around 180 km. A 200 km orbit requires a speed of 7.78 km/s, so getting into a 200 km high orbit requires a specific energy of this, corresponding to this speed. That's 7.54159384 times faster! The formula for the speed of a rocket tells us that to go that much faster requires 693.390852 times as much rocket.

The exact cost of SS1 isn't public, but was probably between $20 and $50 million - I'll say $30 million here. Scaling this up to a low earth orbit capable rocket, we get $20.8 billion. I'm estimating the payload of SpaceShipOne at 400 kg from the rules. The shuttle launches 24,400 kg - 61 times as much. Scaling costs up to something that size, we get $1.2688 trillion The costs of the shuttle program over its entire life? About $145 billion.

Add in the costs of protecting the craft from re-entry from actual orbit, and things start to look expensive.

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Because engineering lends itself to linear projections, after all.

Glad you are in journalism, not engineering, if you think that's a valid (or even remotely intelligble) criticism of Rutan's design philosophy.

posted 08-09-2005 05:29 PM            

quote:

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Originally posted by Rodina:
Because engineering lends itself to linear projections, after all.

Glad you are in journalism, not engineering, if you think that's a valid (or even remotely intelligible) criticism of Rutan's design philosophy.

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posted 08-11-2005 03:41 AM               

Even if we think that 61 times the price of SS1 does not take into account engineering approaches and savings of scale economy, we still need to recognize that SS1 did prove nothing in terms of an operational, in-orbit spacecraft. That is all wishful thinking.

Rutan did beat Shepard on his first ballistic flight and the X-15's - fair enough, but fourty years ago. Let him show he can build an operational spacecraft operating IN space and not just kissing the edge of it, and perhaps go to the Moon as well. Those are the stakes.

posted 08-11-2005 07:29 AM               

Besides, this is a stepping stone. ANYone can see that. Even NASA did Mercury before Apollo, with a lot more funding.

All this negativity. Makes you wonder. Nahhh no it doesn't.

posted 08-15-2005 07:48 PM            

Albatron is right about Rutan doing what he intended. But, lots of folks slide over that and assume that it is a short next step to orbit.

Also bear in mind that SS1 was performing at its peak of capability, while the suborbital Mercury flights were just warm-ups for an almost fully orbit-qualified vehicle (including capability for re-entry from orbital velocity) which could fly in orbit for a whole day (or even three, if Mr. Webb had not nixed the idea in 1963).

Even the X-15 was capable of more than SS1: it was built as both a high-altitude and high-speed vehicle. SS1 had to be going almost straight up where the atmosphere was thin at Mach 3 because it would have come apart if it were to go that fast in the thicker atmosphere, but X-15 did just that, to research the characteristics of hypersonic flight that SS1 later benefitted from.

No negativity here, just giving Rutan due credit for what he accomplished, which was monumental, and looking forward to the day when he or someone else demonstrates how to go the remaining 98% (63/64ths) of the way affordably.

posted 10-05-2005 09:55 PM               

Moreover, Rutan didn't just beat NASA's X-15 and Mercury suborbitals, he stomped them on performance. Firstly, the X-15 program cost $1.5 billion in current day dollars, compared to $30 million for Rutans program (and Rutan's program includes the cost of White Knight, while the $1.5 mil doesn't include the cost of building and operating the B-52 mothership of the X-15).

posted 10-06-2005 07:04 AM               

quote:

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Originally posted by mlorrey:
Actually, SS1 hit mach 5 on the way down, which isn't that much less than the X-15's peak speed of Mach 6.2, which it only reached a few times in its 199 flights. For the most part, the X-15 flew solidly in SS1 flight regime. You also have no idea of the peak performance of SS1. They only flew straight up because they were only interested in altitude.

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Hmm, SS1's hit of Mach 5 was also ONLY REACHED A FEW TIMES IN ITS ALL FLIGHTS.

quote:

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Originally posted by mlorrey:
Moreover, Rutan didn't just beat NASA's X-15 and Mercury suborbitals, he stomped them on performance. Firstly, the X-15 program cost $1.5 billion in current day dollars, compared to $30 million for Rutans program (and Rutan's program includes the cost of White Knight, while the $1.5 mil doesn't include the cost of building and operating the B-52 mothership of the X-15).

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Hmm, I do not want to minimize Rutan's achievement, but I think he knows every detail from X-15 program and his knowledge of aeronautics, technology and aerospace design is more than 40 years further.
Do you really think he could make it for $30 million in 60's?