Author Topic: t/Space CEV Lunar concept 2005  (Read 19419 times)

Online HMXHMX

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Re: t/Space CEV Lunar concept 2005
« Reply #20 on: 08/31/2013 03:25 am »
How the heck do you get $12000/kg to LEO for F9?
F9 v1.1 gets ~16mT to LEO, for roughly $55 million. I get more like $3500/kg. Repeated propellant flights wouldn't need the high level of oversight that usually makes launch costs increase. Are you assuming it'd cost $150 million, and if so, what the heck is the justification for that?
http://www.spacex.com/about/capabilities
$56.5M base price per launch.
13,150 kg to LEO ( more than likely that is 185 km x 185 km ).
We need a higher orbit, less payload the higher it goes as you already know.

We have to add in the tankers cost too and it's mass reduces the amount of propellants delivered, plus boil off and amount unable to transfer to CEV.

Edit:
The cost is based on net mass of delivered propellants to the CEV in a given LEO orbit.

So if we can first work on my post on reply #6 first before we get to far into costs.

I'll note that when I was creating the t/Space plan, my cost requirement was for launches in the 10 ton to LEO class to be at about $20M or less per flight for moderate flight rates (about one per week, nominally).  So it is rather useless to look at current launch costs for SpaceX.  The architecture works for sub-$1000 per pound launches, but probably not for more expensive ones.  (Depends on how much you have to spend, of course, but I was trying to limit launch costs to $1B total per year.)
Thanks, but launch cost don't matter, as any Lunar mission will face launch cost.

After seeing if the CEV can work with today's tech then we can compare costs from one concept to another.

So what is the boil off rate for what we can do today that would work with the mass requirements for the cargo version of the CEV?

The cryo storage was at elevated pressure (about 100 PSIA) and the system used vaporized propellant rather than liquid so it could burn gas-gas, thus, for all practical purposes we didn't boil off at all.  Propellant depots would have used cryocoolers where required, but that was a planned enhancement, not a requirement.

Launch costs were a major factor in the overall economics, however.  The reason is that I was trading lower launch cost against higher start-up costs (i.e., more propellant placed on orbit that a higher tech, higher Isp system, for example).

The whole architecture was built around a public-private partnership (which I believe will no longer happen) and certain assumptions as to what national space policy was (driven by VSE and Stiedle's spiral development).  That architecture is OBE (overtaken by events).
So the CEV hydrogen and the O2 tanks were filled with gas and not liquid?

What was the outside diameter of the CEV were the propellant tankers are?
How many gallons was the size of each propellant tank? What was the max pressure they could handle?
How thick was the outside wall were the crew were?
What was the inside height were the crew were?

Was the tanker from Earth carrying liquid or gas propellants to the CEV in LEO?

Sorry, I no longer have most of that information at my fingertips.  Some of it may be in the NASA briefings that were all public, but it's long gone from my archives.  I vaguely recall the gross mass of the CEV was ~125K lbm.

Let me suggest you need to learn about VaPak (vapor pressurization) propulsion.  That's the approach I was taking at the time.  You'll see why the answer to your first question is "yes."

Online oldAtlas_Eguy

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Re: t/Space CEV Lunar concept 2005
« Reply #21 on: 09/01/2013 01:29 am »
Sorry, but this is not a 1st generation commercial Lunar Lander system but a 3rd or 4th generation system. By then all the assumptions could prove out to be the wrong ones.

Offline RocketmanUS

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Re: t/Space CEV Lunar concept 2005
« Reply #22 on: 09/02/2013 08:43 pm »
How the heck do you get $12000/kg to LEO for F9?
F9 v1.1 gets ~16mT to LEO, for roughly $55 million. I get more like $3500/kg. Repeated propellant flights wouldn't need the high level of oversight that usually makes launch costs increase. Are you assuming it'd cost $150 million, and if so, what the heck is the justification for that?
http://www.spacex.com/about/capabilities
$56.5M base price per launch.
13,150 kg to LEO ( more than likely that is 185 km x 185 km ).
We need a higher orbit, less payload the higher it goes as you already know.

We have to add in the tankers cost too and it's mass reduces the amount of propellants delivered, plus boil off and amount unable to transfer to CEV.

Edit:
The cost is based on net mass of delivered propellants to the CEV in a given LEO orbit.

So if we can first work on my post on reply #6 first before we get to far into costs.

I'll note that when I was creating the t/Space plan, my cost requirement was for launches in the 10 ton to LEO class to be at about $20M or less per flight for moderate flight rates (about one per week, nominally).  So it is rather useless to look at current launch costs for SpaceX.  The architecture works for sub-$1000 per pound launches, but probably not for more expensive ones.  (Depends on how much you have to spend, of course, but I was trying to limit launch costs to $1B total per year.)
Thanks, but launch cost don't matter, as any Lunar mission will face launch cost.

After seeing if the CEV can work with today's tech then we can compare costs from one concept to another.

So what is the boil off rate for what we can do today that would work with the mass requirements for the cargo version of the CEV?

The cryo storage was at elevated pressure (about 100 PSIA) and the system used vaporized propellant rather than liquid so it could burn gas-gas, thus, for all practical purposes we didn't boil off at all.  Propellant depots would have used cryocoolers where required, but that was a planned enhancement, not a requirement.

Launch costs were a major factor in the overall economics, however.  The reason is that I was trading lower launch cost against higher start-up costs (i.e., more propellant placed on orbit that a higher tech, higher Isp system, for example).

The whole architecture was built around a public-private partnership (which I believe will no longer happen) and certain assumptions as to what national space policy was (driven by VSE and Stiedle's spiral development).  That architecture is OBE (overtaken by events).
So the CEV hydrogen and the O2 tanks were filled with gas and not liquid?

What was the outside diameter of the CEV were the propellant tankers are?
How many gallons was the size of each propellant tank? What was the max pressure they could handle?
How thick was the outside wall were the crew were?
What was the inside height were the crew were?

Was the tanker from Earth carrying liquid or gas propellants to the CEV in LEO?

Sorry, I no longer have most of that information at my fingertips.  Some of it may be in the NASA briefings that were all public, but it's long gone from my archives.  I vaguely recall the gross mass of the CEV was ~125K lbm.

Let me suggest you need to learn about VaPak (vapor pressurization) propulsion.  That's the approach I was taking at the time.  You'll see why the answer to your first question is "yes."
1 ) If I'm reading VaPak right the tank pressure is much higher. So aren't the tanks mass also higher than conventional tanks?

2 ) How are the engines cooled?

3 ) Doesn't the hydrogen still need to first be made liquid?
     Same for the O2?

4 ) Could this lander concept be also used for Mars?

This concept would need a 451 ISP or better.

I originally thought this concept would have used CECE ( smaller version than the demo ). This would seem to work with the dry mass ( 6,880 kg ) given for the cargo version.


Edit:
With VaPak is there an issue with how hydrogen is processed?
http://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen
http://en.wikipedia.org/wiki/Hydrogen
« Last Edit: 09/06/2013 01:59 am by RocketmanUS »

Offline Robotbeat

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Re: t/Space CEV Lunar concept 2005
« Reply #23 on: 12/11/2013 04:15 am »
Well, the engines are already pressure-fed (no turbopump), so of course the tanks will be higher pressure (and thus heavier, to a point... they might improve things with fiber reinforcement).
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