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going suborbital to increase the flight rate of SpaceX

Posted by: coal_burner - Sun Nov 25, 2007 9:02 pm
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going suborbital to increase the flight rate of SpaceX 
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Post going suborbital to increase the flight rate of SpaceX   Posted on: Sun Nov 25, 2007 9:02 pm
The one fact that i've never heard disputed on this forum is that "high flight rates reduce costs".
SpaceX, although planning on higher flight rates than any other private rocket company, will probably need several years to launch it's first 100 rockets.
If someone were to remove the second stage from a falcon 1 and replace it with a simple 7 person capsule, you could offer sub-orbital flights on a craft which has already been mostly invented. SpaceX would be able to launch many more falcon1 sized vehicles per year and amortize their launch facilities and personnel over a lot more launches, bringing costs to orbit down.
The capsule could be very simple in design, being that it would only be following a ballistic arc.

1-no RCS system, just A cone shaped vehicle with A heavy weight on the bottom.

2-no heat shield required. simple ablative paint as was used on the SS1 would suffice

3-passenger safety could be taken care of by A solid rocket escape tower that the US and USSR have both used extensively

4 life support is only going to be used for A short period of time, so A simple CO2 scrubber cartridge with make up oxygen tank could be used

5 environmental controls could be A sealed block of ice with fans blowing across it in the bottom of the craft (doubling as ballast).

6 recovery would be the traditional parachute and splashdown.

If A company other than SpaceX were to develop this, does anyone think that SpaceX would be willing to launch it?
Is there something that I'm missing here that makes this idea unfeasible?


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Post    Posted on: Sun Nov 25, 2007 11:07 pm
Cost might be a problem.
Falcon 1 is $7M

Lets say the first stage is $3.5M
No cost to add dragon (lets imagine)
6 passengers & 1 pilot = around $600K per passenger.

If the falcon 1 first stage proves reusable then the price may come down but to match SS1 @ $200K a seat it would need to fall a fair bit.

But with a high flight rate you might make it work.
It would all depend on how reusable the falcon first stage is.

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Post    Posted on: Mon Nov 26, 2007 3:59 am
Personally I would rather fly SS2 or RocketPlane and land on a runway instead of drifting down by parachute to a water landing where I would await "rescue".


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Post    Posted on: Mon Nov 26, 2007 11:41 am
Hello, Freddiiiie,

the prices SpaceX list at present explicitly don't account for reusability.

In the SpaceX-thread I up to now got possible investments into the Merlin of between $ 2.7 mio and $ 3.1 mio using the former launch prices which was $ 6.7 mio for a Falcon 1.

So the $ 3.5 mio you are assuming may be $ 400,000 to $ 800,000 or even less since is impossible that the higher actual prices per launch have to do with the oil price mainly - the propellant costs of the Falcon 1 ere far below $ 100,000 at the former prices.

This would mean a price of $ 57,143 to $ 114,286 per passenger at 7 passengers - extremely competitive to Virgin Galactic's initial price.

But this I consider to be impossible for quite other reasons - seven passengers would weigh around 560 kg. This weight would leave 110 kg maximum for pressurization, seats etc.. The question is how much the vehicle hull, the instruments, the parachute system and so on would weigh. Unfortnately there seem to be no data about the weight of SpaceShipOne but the CXV will weight 3600 kg or more.

In so far I personally think it to be unlikely that suborbital passenger flights could be done using the Falcon 1 - it would have to be the Falcon 5 at least. There the investment into the engine(s) of the first stage would be between $ 13.5 mio and $ 15.5 mio - leaving $ 2.5 mio to $ 4.5 mio at the fromer prices. Then per passenger the price would be between $ 350,000 and $ 650,000.

This is no longer competitive to Virgin Galactic. And the Falcon 5 is not going to be available for now - so the Falcon 9 has to be used where the costs aren't less than at the Falcon 5 and for sure also not competitive to Virgin Galactic.

So suborbital Falcon-flights tend to be interesting for unmanned hardware- and technology-tests only.



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Post    Posted on: Mon Nov 26, 2007 1:57 pm
campbelp2002 wrote:
Personally I would rather fly SS2 or RocketPlane and land on a runway instead of drifting down by parachute to a water landing where I would await "rescue".


That's perfectly reasonable, but I think there is also a market for a 60s retro, flat-on-your-back blastoff/freefall/parachute down experience. If the price was well within 5 figures, it does not even need to 'officially' get into space to be the 'ride of a lifetime'. It may not be rational, but I think there are adventurous people who will want it. I guess this is the kind of customer Starchaser is aimed at.

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Post payload mass   Posted on: Mon Nov 26, 2007 2:35 pm
The spaceX site doesn't have any information on the weight of the falcon1 second stage, but if you look at the pictures of the second stage with the payload fairing mounted on top, the rough dimensions can be deduced by using the fairing dimensions which are given.
The approximate size of the second stage (without engine, interstage, or fairing) appears to be 85" long by 60" dia. The volume of this cylinder would be about 139 cubic FT.
This cylinder, I am assuming is filled with RP1/LOX. with A 2.56 to 1 LOX to RP1 ratio, that would mean 748 gallons of LOX and 292 gallons of RP1.
at 9.49 LBS per gallon of LOX, and 6.8 LBS per gallon of RP1, there is A total of 9084 pounds of liquid in the second stage. Add to that the stated 1474 LB. Falcon 1 payload and you get 10,558 LBS. that the falcon 1 first stage lifts in it's current configuration.
I'm completely ommiting the weight of the kestral engine, the payload fairing, and the second stage tankage since I don't have numbers for those anyway,and their ommission makes everything else seem more conservative.

So, the Falcon 1 could release A sub orbital capsule with A combined passenger/hardware weight of 10,558 LBS. at 297,000 FT at a speed of 3,681 MPH. using it's current flight regime.

It doesn't seem to be much of A stretch to imagine A capsule capable of carrying 7 people being built under that weight limit. Remember the capsule only has to keep people alive and comfortable for A couple of hours while loading propellant, countdown, launch, and landing.
After splashdown, the hatch can be opened while waiting for recovery.


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Post Re: payload mass   Posted on: Tue Nov 27, 2007 2:01 pm
coal_burner wrote:
The spaceX site doesn't have any information on the weight of the falcon1 second stage,
Yes it does; on page 10 of the Payload User's Guide.
http://www.spacex.com/Falcon%201%20Payl ... 0Guide.pdf
Dry mass is 1,125 lb and usable propellant mass 8,881 lb. So total is 10,006 lb, not including unusable propellant (if there is any). It also says the first stage fairing (which I assume is the interstage) is about 300 lb and the second stage fairing is 346 lb.


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Post    Posted on: Tue Nov 27, 2007 6:31 pm
Wow. even better than I thought
1,125 Lb second stage
+8,881 Lb fuel
+346 Lb fairing
+1,474 Lb payload
=11,826 Lbs
Plus A little extra for unuseable propellant (there is ALWAYS some unuseable propellant. they put extra fuel in to insure that the rocket engine doesn't hiccup and caugh A few times before programmed shutdown).
It would probably not be A good idea for SpaceX to pursue this, because it would only dilute their developement resources (mostly creative brainpower, not money).
It just seems that this system could be developed by A third party for A small fraction of what is being spent on SS2 WK2.


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Post    Posted on: Tue Nov 27, 2007 7:11 pm
coal_burner wrote:
Wow. even better than I thought

<snip>

It would probably not be A good idea for SpaceX to pursue this, because it would only dilute their developement resources (mostly creative brainpower, not money).
It just seems that this system could be developed by A third party for A small fraction of what is being spent on SS2 WK2.


Yes, you certainly fell on your feet with your first estimate!

As for SpaceX, in their shoes I would not see this as consistent with the kind of corporate image I want to present. They would also need to think about the effect an accident would have on their image, even if they had sold a rocket outright to another operator. I suspect anyone providing a service like this will have to use a rocket developed within the 'space adventure' industry. I don't think Elon Musk sees himself as part of that.

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