40% less than the maximum payload capability of White Knight II at 50,000ft
But what is that, you may well ask, and how on Earth did you find that out?
On the afternoon of 23 January Virgin Galactic president Will Whitehorn said to me in a one-on-one interview , "White Knight II has the [payload] capacity for 40% more weight than SpaceShipTwo is."
I think WK2's payload capacity is 13,600kg (30,000lb)
So that makes SS2's mass, drum roll please, 9,740kg or 21,428lb
So why am I so ready to pick 30,000lb as the WK2 capacity?
I actually got the original WK2 payload capacity figure from an individual from the Swedish Space Corporation (SSC) when I was at the SSC/Virgin Kiruna, Sweden spaceport event last year
SSC wanted to launch sounding rockets from WK2 over Sweden's Esrange test site in its northern latitudes and so they had been told the payload capability. At first Galactic did not want to confirm this but have since
On Wednesday this week Will Whitehorn's exact words in my one-on-one interview were that WK2 could "carry more than 30,000lb to 50,000ft"
(However at the UK's Rutherford Appleton Laboratory space event last year Whitehorn said that it could carry 30,000kg, yes I mean kilograms, but then he did not reply to my email asking for clarification)
But despite all that I prefer to stick with the SSC official's statement. Why?
When I asked Will what the landing speed of SS2 was he said "at least 115kt". Did that mean 300kt I asked. "No", he said, laughing, "that would be too much." So now you understand the game that is being played
For commercial reasons they don't want to give exact figures but when potential customers blab them there is a standard public relations reaction of fudging the issue
With the evidence I have I will say that while WK2 can carry 30,000lb to 50,000ft, safely, I admit that when needed perhaps, as a guess, it could probably pull 2,000lb more but it will be pushing the envelope
Other facts I know that bolster this view are that;
Whitehorn told me that WK2 will, when not mated with SS2, be able to carry out a "viking departure". To put that in layman's terms it is where the aircraft climbs vertically, on its tail, immediately after taking off
And the reason for four engines for WK2 is that there is a requirement for an engine out capability. Alex Tai told me they wanted an 'on take-off' engine out capability last year
on January 27, 2008 3:30 AM | Reply
Rob,
I'm skeptical about that 21klb number. That's actually less mass per person than SS1, which was a much more cramped vehicle. I'd be much more willing to believe that SS2 was 30klb (which would imply about 40% more weight per person than SS1), and that WK2's capability was 42klb. That would also jibe much better with what I've heard from my sources.
It'll be interesting to see (on the final analysis) what the numbers really come out to.
~Jon
on January 28, 2008 5:57 AM | Reply
Great work!
But...
"The mass of Virgin Galactic's SpaceShipTwo is...
40% less than the maximum payload capability of White Knight II at 50,000ft"
... don't you mean the mass of SS2 is 29% less than the maximim payload of WK2?
on January 28, 2008 2:49 PM | Reply
Well spotted Brad, you're right. Now why did I write that?
What I was told by Will Whitehorn was, "WK2 can lift 40% more than the mass of SS2."
So I was trying to be clever and re-word it.
Just to clarify, SS2's mass is multiplied by 1.4 (for 40% more than than its mass) to equal the WK2 payload capability.
If we take that capability as 30,000lb, then the equation is, SS2 mass (aka x) multiplied by 1.4 equals 30,000lb. So to get x we divide 30,000 by 1.4.
Although the press materials on 23 January state that SS2 is twice as large as SpaceShipOne, previous comments to me and others put SS2 as being three times larger than SS1.
On Jon Goff's point about mass share; I have in my notes that Burt Rutan said at a meeting of the UK'S Royal Aeronautical Society that SS1's mass was 6,600lb (3,000kg). So that is 2,200lb per person - remember SS1 flew with the payload mass of three people to meet the X Prize requirements. Mike Melville and Brian Binnie had with them on each of their flights ballast for two more notional people.
If SS2 is 21,428lb then with eight people aboard that is 2,668lb each. So SS2 has MORE mass share than SS1. Phew!
on January 28, 2008 3:40 PM | Reply
"Rob,
I'm skeptical about that 21klb number. That's actually less mass per person than SS1, which was a much more cramped vehicle. I'd be much more willing to believe that SS2 was 30klb (which would imply about 40% more weight per person than SS1), and that WK2's capability was 42klb. That would also jibe much better with what I've heard from my sources.
It'll be interesting to see (on the final analysis) what the numbers really come out to.
~Jon"
The more cramped vehicle, SS1, had more surface area per volume and consequently more weight per seat. SS2 has less surface area per volume and consequently less weight per seat.
on January 28, 2008 4:00 PM | Reply
Rob,
We'll have to agree to disagree, but based on specs I've heard for the propulsion system, there's no way, IMO, the vehicle only weighs 21klb. But I can't really go into the details at this moment, so we'll just have to wait and see.
My personal guess, now that I have more details:
SS2 GTOW is ~28-30klb, and WK2 max payload is 40-45klb.
~Jon