Burt Rutan said that White Knight II (WK2) could launch a two-stage rocket and put a single person into low Earth orbit, at the end of the Virgin Galactic SpaceShipTwo (SS2) and WK2 press conference
Flight learnt that WK2 has a 13,600kg (30,000lb) payload capacity sometime back
And in August 2004 Rutan told the Royal Aeronautical Society that he could envisage an orbital transportation system
As a very crude rule of thumb a payload is about 10% of a launch vehicle and its payloads combined gross lift off weight
So with a 13,600kg payload, a 1,300kg capsule could be launched, in theory. If you assume the passenger has an "average" mass of 90kg then there is 1,20kg left for the spaceship's systems. Not much
Despite this fantastic claim Burt said that he did not have a customer for his one-person LEO spaceship and that Scaled only built vehicles for customers
Fishing for a contract, Burt?
on January 23, 2008 9:59 PM | Reply
A fair chunk of that 90% structure and fuel mass fraction in a conventional launch vehicle would be used to get you from MSL to ~50,000 ft. The WKII carrier is essentially the reusable first stage of the SS2, so the payload mass fraction should increase for an air launched orbiter.
Regardless, Rutan has spoken of the need for breakthroughs akin to the feather mechanism to make a "Tier 2" LEO system a reality, and that his focus is first on getting the suborbital spaceliner certified. I wouldn't expect to hear anything on orbital until at least the flight test program for SS2 is showing significant progress.
on January 23, 2008 10:19 PM | Reply
Good point Sean. The mass fraction would be improved but off the top of my head staging at 50,000ft seems a little low although you are above most of the atmosphere at that point. As for what comes immediately after Tier 1b's SS2 early in the next decade, I will be writing about Virgin Galactic's plans for just that soon, so keep checking back to flightglobal.com and Hyperbola
on January 23, 2008 10:50 PM | Reply
1,300kg minus 90kg equals 1,210kg, which sounds like a possibly feasible rocket/capsule-combination.
on January 23, 2008 11:16 PM | Reply
Well done Soeren for spotting the typo, yes that should be 1,200kg and not 1,20kg. I can't find a mass for NASA's Mercury programme's Friendship-7 capsule but its occured to me you need a launch abort system and that is not going to be light, so I am more sceptical now that you would get a viable manned capsule for 1.2 or 1.5 tonnes.
on January 24, 2008 12:01 AM | Reply
Rob,
Are you sure the lift capacity of WK2 was only 30,000lb and not 30,000kg? I've seen both numbers used, but 30,000lbs seems a bit small. Their engine for SS2 is about 5x higher thrust than SS1's engine, and assuming that they don't have a higher liftoff thrust (which doesn't appear to be the case based on the peak G's they're citing), that would have SS2 tipping the scales at about 40,000lb give or take (roughly 5x SS1's 8000lb GTOW). 5x bigger makes a lot of sense when you're talking about almost 3x the people (8 instead of 3), and a lot more space per person. If SS2 is really 40klb, it would make sense that WK2 is oversized a bit (enough for some growth margin). If the real number is 30,500kg like I've seen in some places, that comes out to ~67.5klb.
For comparison Falcon 1 is ~66klb (or at least the earlier version was, I don't know what 1e will be).
Using WK2 to make an orbital launcher for 1-3 people might be possible (I went a bit into some of the relevant trades back a few weeks ago on Selenian Boondocks, and should be posting another related article on a TSTO approach in the near future), though there are several challenges. Keeping the dry mass low enough, keeping the propellants from boiling off on the way up, and TPS for the way down would all be challenges. But it's not impossible by any stretch of the imagination.
~Jonathan Goff
on January 24, 2008 12:06 AM | Reply
I think you meant that 10% of the gross lift off weight (GLOW) is the launch vehicle empty weight (engines, tanks, plumbing, etc.) AND the payload. Payloads are typically 1% to 3% of the launch vehicle GLOW, depending on proplusion and number of stages.
on January 24, 2008 12:09 AM | Reply
Hi Jon,
Thanks for the comment. I had a one-on-one interview with Wil Whitehorn today and he told me that White Knight II can carry 30,000lb, not kilograms, to 50,000ft.
I first found this out when I was in Kiruna, Sweden and one of the Swedish Space Corporation people blabbed to me that that was its payload capacity because they wanted to launch sounding rockets from it.
I now also know the mass of SpaceShipTwo but I don't want to scoop myself so you will have to wait for that.
I have got to go to the Virgin Galactic party now here in New York and I will approve comments (so feel free to post) and respond when I get back, whatever silly o'clock that is...
on January 24, 2008 12:26 AM | Reply
Huh. If Whitehorn said 30klb, he would know better than I would, but that really doesn't make sense then with other numbers I've heard for other things. It also seems really low compared to what I would've expected from something the size of WK2. But if that's the number he gave you, I guess I can't argue. Will actually works directly with them, I just work at another rocket shop across the street.
~Jon Goff
Mojave
on January 24, 2008 12:32 AM | Reply
On further thought (looking back over some of those numbers I've heard, and the numbers they give for G-loads that they're training people for), I guess ~28klb for SS2 might be reasonable (which would still leave ~2000lb of margin for WK2).
In that case, I really doubt you could make an orbital vehicle work in that weight class, especially a manned one. You might (with LOX/LH2) be able to put a Falcon 1 sized payload into orbit on an expendable vehicle launched from WK2, but I doubt you could do very much beyond that.
~Jon
on January 24, 2008 2:22 AM | Reply
" Scaled only built vehicles for customers "
Was SpaceShipOne built for a customer? Virgin didn't announce any partnerships until SpaceShipOne was flying, so I don't think it was them.
Mabe Rutan thought of the X-prize money as a customer?
My guess is that after SS2/WK2 is flying and doing well, Rutan will send up his version of Sputnik, with or without a customer. Manned orbital flight, needing a proper SpaceShipThree would wait for investment.
on January 24, 2008 4:48 AM | Reply
Well Justin, the customer for SS1 was one of Microsoft's founders, Paul Allen. He paid the alleged cost of $25 million for SS1s development. His company Mojave Aerospace Ventures owns the IP for SS1 systems.
As for SpaceShipThree, it may not be the orbital vehicle you think it would be. But that is for another story cum blog.
As for Jon Goff, I'll end his agony over the mass of SS2 in the next few days. Your close Jon, but no cigar...
on January 24, 2008 4:28 PM | Reply
SpaceShipOne was closer to 6,000 lbs than 8,000 lbs, which means that SS2 is probably just under 30,000 lbs. The WK2 payload numbers of 30,000 kg and 30,000 lbs are probably both correct, because WK2 can probably carry a 30,000 kg sounding rocket to 10,000 feet and only a 30,000 lb SpaceShipTwo to 50,000 feet because effective thrust and lift are cut in half at 50,000 foot altitude. At best, WK2 can probably carry a rocket with a 1,000 lb, 1-man capsule to low earth orbit for 2 to 3 orbits and an automatic reentry.
~ Anonymous
on January 24, 2008 5:43 PM | Reply
Sorry Anonymous, you are COMPLETELY wrong. I am off shopping now, it's not every day you get a couple of hours free in New York, especially when the pound is so strong against the dollar. But tomorrow, when I am back in London, I will reveal the mass of SpaceShipTwo and explain how I know...