# SpaceShipOne : Platform for orbit?

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#### rogerinnh

##### Guest
SpaceShipOne is capable of carrying two passengers to space in a sub-orbital flight. Let's say that's about 150 pounds per passenger for a total of 300 pounds of. If, instead of two passengers it took an additional rocket that was launched from SpaceShipOne at its apogee. Could a 300 pound rocket have enough fuel to accellearate it to the 17,000 mph necessary to put it into orbit?<br />In other words, could SpaceShipOne provide a platform for getting small satellites into orbit?

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#### bobvanx

No.

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##### Guest
I think what you really asking is whether a 300 pound (140kg) rocket could be accelerated from 0 - 17,500mph in zero gravity with a orbital trajectory that include increasing its altitude by about 100 miles?<br /><br />I think just one of the problems is that 17,500mph is what's required to beat Earth's gravity, anything not rocketing away from the planet or not already travelling at that speed or faster at a tangent to the Earth's surface will quickly get pulled back down.<br /><br />The other problem is: Does a 300 pound chemical rocket have enough fuel to achieve the correct altitude and sufficient speed? Perhaps not.<br /><br />But I could be wrong.

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#### bobvanx

##### Guest
The WK (or its big sister) could carry a small orbital rocket. WAG a 6,000 lb rocket that could put most of its thrust into getting to 5 miles per second and just a few percent overcoming the last bits of atmospheric drag, could deliver a microsat.<br /><br />Um, actually, no. A quick Google turned up the numbers that the rocket would have to be bigger than WK can carry.

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#### aaron38

##### Guest
That's basically the Pegasus rocket profile.<br /><br />The Pegasus weighs in at 51,000 pounds, and gets only 600 lbs to orbit.

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#### nacnud

##### Guest
how much bigger than WK can carry, remember the extendable wings...

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##### Guest
> <i><font color="yellow">In other words, could SpaceShipOne provide a platform for getting small satellites into orbit?</font>/i><br /><br />That is one of the business markets XCOR would like to go after. See:<br /><br /> http://www.xcor.com/suborbital.html<br /></i>

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#### mikejz

##### Guest
I think getting 10 or 20 lbs into orbit might be doable. Esp if SS1 were striped down and piloted by remote. Of course there is no rule that WK is required to get SS1 Airborne, other planes could be used. I really do wonder what Rutan is think in terms of getting to Orbit......

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#### bobvanx

##### Guest
Rocket-powered flyback boosters!<br /><br />That'd be way cool.

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#### mikejz

##### Guest
Exactly, Of course I'm no expert on the Pegesis booster. It should would be nice to see development of a cheap second stage--I think thats key right now.

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#### liquidspace2k

##### Guest
For the SpaceCraft that is being build for the Virgin Galactica company by Scaled Composities, is going to be a bigger version of the SS1, which is suppose to carry 5 passenger and with 2 pilots, i believe, and i believe that they are planned to upgrade the White Knight as well, possibablly making a bigger version of that to carry the extra weight...<br /><br />The Wight Knight is suppose carry the X-37, so it can be tested in the air... is there even enought space under the White Knight to carry the X-37... i always believed the X-37 was bigger than the SS1... and it looks like to me that the SS1 sits pretty close to the ground.. so a bigger ship looks like it wont fit... anyone know if the X-37 can actually fit under the White Knight

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#### spacester

##### Guest
OK, let’s see here . . . you’re asking "If SS1 could eject a third stage at apogee massing 300 pounds total, with no impact on the current flight profile or alterations to either existing craft, what payload could that third stage carry?"<br /><br />It’s a fair question; certainly such a third stage would have some payload greater than zero.<br /><br />Let’s assume no horizontal velocity at the release point of 112.2 km and we need to get to an orbit of 400 km.<br /><br />The specific potential energy at 112.2 km is equivalent to a deltaV of 1.41 km/s<br />A 400 km circular orbit requires specific orbital energy equivalent to 8.14 km/s of deltaV<br />8.14 – 1.41 = 6.73 km/s<br /><br />If you have the deltaV needed and the Specific Impulse of the engines you’re going to use, you have everything you need to allocate the total mass to propellant, payload and other inert mass. Check out this thread for details. (Maybe someday someone else will do these simple calcs, but at this point I'm not holding my breath)<br /><br />Let's assume engines with Isp = 350 seconds<br /><br />So<br />pf = 1 - 1 / (e ^ (Vf / Ve)) <br />Vf = 6.73 km/s <br />Ve = g * Isp = 9.807 * 350 = 3.432 km/s <br />pf = 0.859<br />Which means that 85.9% of the 300 pounds will be propellant.<br />This leaves 42.217 pounds for the payload PLUS the mass of the engines and the tanks and the rest of the mechanical systems of the stage. The empty propellant tanks would mass less than 8% of the mass of the propellants they will hold, that's <br />0.859 * 300 * 0.08 = 20.6 pounds for the tanks<br />So go shopping for engines that only mass around 10 pounds.<br />Assume the rest of the stage would mass around 5 pounds<br />That leaves you with <br />42.2 - 20.6 - 10 - 5 = <br />6.6 pounds of payload<br /><br />Not much, but greater than zero. <br /><br />Note that if I run the same numbers <div class="Discussion_UserSignature"> </div>

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#### mrmorris

##### Guest
<font color="yellow">"The Wight Knight is suppose carry the X-37, so it can be tested in the air"</font><br /><br />No -- the person who was being interviewed in the article where that information was printed (I forget his name) has already issued a qualifier/correction. He said he'd told the reporter that Scaled Composites would be supplying the lift aircraft in lieu of using a B-52, <b>not</b> that the White Knight in particular would be doing so. This caused speculation in an earlier thread about WK's successor.

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#### najab

##### Guest
><i>Note that if I run the same numbers with Isp = 425 seconds the payload becomes...</i><p>Yeah, but would <b>you</b> want to climb into SS1 with a tankful of liquid hydrogen? <img src="/images/icons/wink.gif" /></p>

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#### bobvanx

##### Guest
Wow, mikejz! Your guess of 10 to 20lbs is in the correct order of magnitude!<br /><br />Thanks, spacester, for crunching the numbers.

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#### bobvanx

##### Guest
Doea anyone know the ISP for laughing gas and rubber? I recall it's lower than others; is it around 250? 275?<br /><br />If it's 275, then <br /><br />pf = 1 - 1/(e^(6.73/2.69), = .92<br /><br />So a 6,000 lb rocket (WK carrying full payload as a rocket) has 5500 lbs of propellent, and 500 lbs of engines/tank/aeroshell/payload.<br /><br />If the tanks are still just 8% the mass of their load, that's 440 lbs, leaving just 60 lbs for engines, structure, and payload...<br /><br />Looks like ISP matters a whole heckuva lot!<br /><br />Oops, I goofed. I used the deltaV numbers from SS1's apogee. If I reset Vf = 8.41 km/s, then I get... 95% fuel fraction?

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#### bobvanx

##### Guest
The entire SpaceDev contract was \$400,000, I found out over on Motley Fool.<br /><br />Can I hazard a guess about how expensive a satellite launch from SS1 is?<br /><br />30 people, licensing, fuel loads... Or work it another way, Branson says he can make money charging \$200k per passenger, so operating costs would be... half? a third?<br /><br />Anybody know?<br /><br />I'll just assume a range. \$100k to \$300k per flight of SS1.<br /><br />Therefore, that roughly 10 lb payload costs \$10k to \$30k per pound to send to orbit.

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#### bobvanx

##### Guest
Thanks!<br /><br />So I'm not far off; SS1 as a platform yields a \$8,000 per pound launch cost.<br /><br /> The other shoe just dropped. \$79,000? His labor costs must be really, really low. My empathy just came up for his employees: they've got to be zealots, and really committed to what they are doing. Boy o boy, I sure wish all them all the fruits of their labors.

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#### propforce

##### Guest
<i>".... Yeah, but would you want to climb into SS1 with a tankful of liquid hydrogen? ..."</i><br /><br />Why? Is it better with a tankful of laughing gas? Laughing all the way to space? <img src="/images/icons/laugh.gif" /><br /><br /> <div class="Discussion_UserSignature"> </div>

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#### gpurcell

##### Guest
"I recall Rutan saying that a SS1 launch runs \$79,000."<br /><br />That must be referring to the variable costs involved with a launch (permits, fuel, overtime, etc.) Without a specified flight rate, there's no way he can develop a fixed cost per flight number.

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#### mrmorris

##### Guest
<font color="yellow">"I recall Rutan saying that a SS1 launch runs \$79,000. "</font><br /><br />Unfortunately -- we don't know what was being accounted for in that figure. Does it include all of the man-hours prepping WK and SS1 for flight? Does it include the costs of the chase planes? Does it include the extra costs involved in the amount of flight diagnostics being performed on these test flights?<br /><br />I would *guess* that the figure would include all of these. If Burt had a number off the top of his head -- it should have been something that they'd worked out in the form of: "How much is each powered test flight going to impact the bottom line". I seriously doubt they would have worked out a number that would answer a question like "If we eliminated all non-critical expenses -- how much would a powered flight cost".<br /><br />(Marcel -- please skip the next bit.)<br /><br />Ergo -- a cost-optimized flight would likely be a significant amount less than the stated 79K.

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#### propforce

##### Guest
<font color="yellow"><i>"... I recall Rutan saying that a SS1 launch runs \$79,000. ..."</i></font><br /><br />That's amazing. I would think the replacement of hybrid rocket alone would cost \$79K or more on each flight. <div class="Discussion_UserSignature"> </div>

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#### propforce

##### Guest
Would peanuts and drinks be served as well ? <div class="Discussion_UserSignature"> </div>

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#### bobvanx

##### Guest
No, silly. M&Ms and 7*up

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#### kmarinas86

##### Guest
What about 7up candy bars and M&M soda?

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