Author Topic: CEV/EELV Discussion – Warning not for the Politically Correct  (Read 43503 times)

Offline kevin-rf

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mlorrey - 5/6/2006  10:55 PM

If the ET were redesigned to handle LOX and RP-1, it would be structurally a bit heavier, but could carry twice as much payload into orbit for the same tankage volume. RP-1 remnants should evaporate to space upon venting.


The bulk of the hydrocarbons may "evaporate" out, but there will always be a thin film left on the tank walls. Ever try to pump down a vacuum chamber after it was contaminated with oil? You can pump against it until you turn blue (Cryo Pump,Diffusion Pump,Turbo Molecular Pump,chose your weapon) and never get much beyond the milli torr range because of the hydrocarbons left behind. The RP-1 will have to be scrubbed out by hand.  I can lay may hands on a small vacuum chamber that had an oil handling accident (#@$! oil roughing pump) , It has been scrubbed, and I can still smell the oil in it.

The RP-1 tank will be 1/16th the size of the O2 tank. Why mess with the RP-1 tank at all.
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Offline simonbp

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kevin-rf - 6/6/2006  11:18 AM

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mlorrey - 5/6/2006  10:55 PM

If the ET were redesigned to handle LOX and RP-1, it would be structurally a bit heavier, but could carry twice as much payload into orbit for the same tankage volume. RP-1 remnants should evaporate to space upon venting.


The bulk of the hydrocarbons may "evaporate" out, but there will always be a thin film left on the tank walls. Ever try to pump down a vacuum chamber after it was contaminated with oil? You can pump against it until you turn blue (Cryo Pump,Diffusion Pump,Turbo Molecular Pump,chose your weapon) and never get much beyond the milli torr range because of the hydrocarbons left behind. The RP-1 will have to be scrubbed out by hand.  I can lay may hands on a small vacuum chamber that had an oil handling accident (#@$! oil roughing pump) , It has been scrubbed, and I can still smell the oil in it.

The RP-1 tank will be 1/16th the size of the O2 tank. Why mess with the RP-1 tank at all.

Also, any foam dust that "popcorns" off will possibly redeposit itself on other parts of the station, like the solar wings, for example. Over time, this could be a major problem...

Simon ;)

Offline mlorrey

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kevin-rf - 6/6/2006  11:18 AM

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mlorrey - 5/6/2006  10:55 PM

If the ET were redesigned to handle LOX and RP-1, it would be structurally a bit heavier, but could carry twice as much payload into orbit for the same tankage volume. RP-1 remnants should evaporate to space upon venting.


The bulk of the hydrocarbons may "evaporate" out, but there will always be a thin film left on the tank walls. Ever try to pump down a vacuum chamber after it was contaminated with oil? You can pump against it until you turn blue (Cryo Pump,Diffusion Pump,Turbo Molecular Pump,chose your weapon) and never get much beyond the milli torr range because of the hydrocarbons left behind. The RP-1 will have to be scrubbed out by hand.  I can lay may hands on a small vacuum chamber that had an oil handling accident (#@$! oil roughing pump) , It has been scrubbed, and I can still smell the oil in it.

The RP-1 tank will be 1/16th the size of the O2 tank. Why mess with the RP-1 tank at all.

Well, I know one way to get rid of the RP-1: after venting, seal and fill with 100 millibars of pure O2. Light a match. The resulting combustion will not overpressure the tank.
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Offline mlorrey

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simonbp - 6/6/2006  11:35 AM

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kevin-rf - 6/6/2006  11:18 AM

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mlorrey - 5/6/2006  10:55 PM

If the ET were redesigned to handle LOX and RP-1, it would be structurally a bit heavier, but could carry twice as much payload into orbit for the same tankage volume. RP-1 remnants should evaporate to space upon venting.


The bulk of the hydrocarbons may "evaporate" out, but there will always be a thin film left on the tank walls. Ever try to pump down a vacuum chamber after it was contaminated with oil? You can pump against it until you turn blue (Cryo Pump,Diffusion Pump,Turbo Molecular Pump,chose your weapon) and never get much beyond the milli torr range because of the hydrocarbons left behind. The RP-1 will have to be scrubbed out by hand.  I can lay may hands on a small vacuum chamber that had an oil handling accident (#@$! oil roughing pump) , It has been scrubbed, and I can still smell the oil in it.

The RP-1 tank will be 1/16th the size of the O2 tank. Why mess with the RP-1 tank at all.

Also, any foam dust that "popcorns" off will possibly redeposit itself on other parts of the station, like the solar wings, for example. Over time, this could be a major problem...

Simon ;)

Any ET that uses RP-1 is going to need a lot less foam, ergo less popcorning, if any. However, the popcorn affect that is alleged is why I've proposed wrapping or sleeving the tank in orbit by orbital personnel.
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Offline kevin-rf

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mlorrey - 6/6/2006  12:22 PM

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kevin-rf - 6/6/2006  11:18 AM

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mlorrey - 5/6/2006  10:55 PM

If the ET were redesigned to handle LOX and RP-1, it would be structurally a bit heavier, but could carry twice as much payload into orbit for the same tankage volume. RP-1 remnants should evaporate to space upon venting.


The bulk of the hydrocarbons may "evaporate" out, but there will always be a thin film left on the tank walls. Ever try to pump down a vacuum chamber after it was contaminated with oil? You can pump against it until you turn blue (Cryo Pump,Diffusion Pump,Turbo Molecular Pump,chose your weapon) and never get much beyond the milli torr range because of the hydrocarbons left behind. The RP-1 will have to be scrubbed out by hand.  I can lay may hands on a small vacuum chamber that had an oil handling accident (#@$! oil roughing pump) , It has been scrubbed, and I can still smell the oil in it.

The RP-1 tank will be 1/16th the size of the O2 tank. Why mess with the RP-1 tank at all.

Well, I know one way to get rid of the RP-1: after venting, seal and fill with 100 millibars of pure O2. Light a match. The resulting combustion will not overpressure the tank.

Raised EyeBrow... So you have replaced uncombusted hydrocarbons with partially combusted hydrocarbons and soot that will be sticking on the walls. The heavier hydrocarbons that stayed behind (more tar like than RP-1 like) will not burn as easily as bulk RP-1. The lighter components will have boiled off.

The other problm is the tanks are an Al alloy. Most Al alloys are quite porous, making it dificult to clean out left over RP-1. We are not talking about Stainless...  

Brings up another question. How easy is it to burn the AlLi used in the ET? Anyone have the ingnition temp of AlLi handy?
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Offline Jim

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mlorrey - 6/6/2006  1:27 PM
QUOTE]

Any ET that uses RP-1 is going to need a lot less foam, ergo less popcorning, if any. However, the popcorn affect that is alleged is why I've proposed wrapping or sleeving the tank in orbit by orbital personnel.

RP-1 and LO2 tanks don't need insulation or foam

Offline J Britt RSA

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mlorrey - 5/6/2006  5:35 PM

Here's my proposed LV constellation, which would put into LEO a regular supply of ETs for salvage or use in space station modules. The ETs would launch with framing, grille decking, hatches, and conduits installed in the tanks, with a fuel scavenge system in the intertank and deployable solar panels on the sides. These ET launchers would drop all but one main engine at 65-70% of fuel burned, to boost payload in orbit. The engines may or may not be recoverable and/or reusable.

mlorrey - do you have a bigger version of the ext_tank_ssto_small.jpg ? As a hobby rocketeer, i'm interested in your design.

Offline mlorrey

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J Britt RSA - 6/6/2006  7:31 PM

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mlorrey - 5/6/2006  5:35 PM

Here's my proposed LV constellation, which would put into LEO a regular supply of ETs for salvage or use in space station modules. The ETs would launch with framing, grille decking, hatches, and conduits installed in the tanks, with a fuel scavenge system in the intertank and deployable solar panels on the sides. These ET launchers would drop all but one main engine at 65-70% of fuel burned, to boost payload in orbit. The engines may or may not be recoverable and/or reusable.

mlorrey - do you have a bigger version of the ext_tank_ssto_small.jpg ? As a hobby rocketeer, i'm interested in your design.

Yeah, but it's too big to upload. PM me your email and I'll send it to you.
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Offline publiusr

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Kayla - 26/5/2006  6:15 AM



These comments get to the heart of why I have suggested the use of smaller launchers with cryo transfer instead of the CaLV.  The CaLV is so large that it will only fly occasionally,

Same with Delta IV--which has no engine out. CaLV is a must for it reduces assembly and is a step into the future of real space. EELV assembly is daft--and ISS's delays are proof of that. This 20 ton at a time stuff is thre wrong way to go.

Offline bad_astra

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Raytheon and others had perfectly acceptable plans that wouldn't have required too many launches to build a lunar base. For whatever reasons ESAS chose to ignore all of them.
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Offline mlorrey

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bad_astra - 10/6/2006  12:32 AM

Raytheon and others had perfectly acceptable plans that wouldn't have required too many launches to build a lunar base. For whatever reasons ESAS chose to ignore all of them.

Mustn't talk about "reasons", you'll be accused of promoting "conspiracy theories".
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Offline gladiator1332

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publiusr - 9/6/2006  5:47 PM

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Kayla - 26/5/2006  6:15 AM



These comments get to the heart of why I have suggested the use of smaller launchers with cryo transfer instead of the CaLV.  The CaLV is so large that it will only fly occasionally,

Same with Delta IV--which has no engine out. CaLV is a must for it reduces assembly and is a step into the future of real space. EELV assembly is daft--and ISS's delays are proof of that. This 20 ton at a time stuff is thre wrong way to go.

Totally agree with you. We have barely flown the Delta IV so we do not know if there are problems hidden somewhere. We'll have a delay and a half finished spacecraft floating around up there wasting away.


Offline bad_astra

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FGB was given a waiver with the understanding it would be corrected later (insert eye roll). I don't see why the same thing could not be done in this case.
"Contact Light" -Buzz Aldrin

Offline Kayla

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gladiator1332 - 10/6/2006  8:08 PM

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publiusr - 9/6/2006  5:47 PM

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Kayla - 26/5/2006  6:15 AM



These comments get to the heart of why I have suggested the use of smaller launchers with cryo transfer instead of the CaLV.  The CaLV is so large that it will only fly occasionally,

Same with Delta IV--which has no engine out. CaLV is a must for it reduces assembly and is a step into the future of real space. EELV assembly is daft--and ISS's delays are proof of that. This 20 ton at a time stuff is thre wrong way to go.

Totally agree with you. We have barely flown the Delta IV so we do not know if there are problems hidden somewhere. We'll have a delay and a half finished spacecraft floating around up there wasting away.


You are worried about the fact that the Delta IV has barely flown????  With 5 successful flights under Delta's belt, and 8 for Atlas V the EELV program is well on its way of demonstrating its reliability and capability with 2 independent rockets.  Yes, Delta has had some major delays, but that is typical of new rocket programs.  The DoD is paying to get through this rough period and Delta will be fully operational in the next couple of years, long before the CLV even demo flight in 2009.  Atlas V, having the advantage of being more derived than Delta IV, has been very successful in meeting its launch day promises, averaging about 1 day of delay for the past 6 launches.

With the SDLV CLV on the other hand, NASA will have to pay for the full development cost and then all of the early flight glitches as well and then NASA gets the benefit of paying for the full infrastructure cost of this NASA only rocket system.  CLV is currently the long pole for replacing the Shuttle, with an ILC of 2012 and first crew flight in 2014.  Any additional delays will further delay America's human space program.  A couple of years delay is likely based on past programs.  Are we willing to have a likely 6 year period with no American crew access to space?  Do we continue to launch shuttles during this period, draining $4 to $5B from exploration.  These issues are likely to jeopardize sending astronauts to the moon prior to 2020!!!

Offline Kayla

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Norm Hartnett - 28/5/2006  11:55 PM

So in amongst the massive amount of OT stuff in this thread we got some possibly good data on the Atlas packages. Anyone want to present the Delta packages?

Everything I read indicates that Griffin is not in love with the Stick and this thread http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=2710&posts=5&start=1 indicates he isn't wed to ESAS's version of manrated either.


Griffin:
"Many, if not most, unmanned payloads are of very high value, both for the importance of their mission, as well as in simple economic terms. The relevant question may be posed quite simplistically: What, precisely, are the precautions that we would take to safeguard a human crew that we would deliberately omit when launching, say, a billion-dollar Mars Exploration Rover (MER) mission? The answer is, of course, “none”. While we appropriately value human life very highly, the investment we make in most unmanned missions is quite sufficient to capture our full attention."

As Griffin says, crew or expensive hardware, NASA will want to the most reliable launch vehicle to fly the expensive payloads.  The CaLV (1:124 failure rate) has a substantially lower reliability than the CLV (1:460 failure rate) according to ESAS: http://www.nasa.gov/pdf/140637main_ESAS_06.pdf, pages 382 & 384.  Although, I by and large disagree with most of ESAS's findings, the concept that a larger, more complex rocket has a lower reliability than a smaller less complex vehicle makes sense.  Large rockets will also have very low flight rates, further reducing the demonstrated reliability.

This is one of the many reasons that I support utilizing smaller rockets than the CaLV to under take exploration.

Folks on this site that are suggesting that smaller launches will require unworkable complex orbital assembly are confusing the ISS experience with what can be for exploration.  I've been suggesting launching the EDS & LSAM on the CLV (EELV derived is my preference), empty of propellant.  Then launch propellant to the EDS on any and all rockets available.  There are daily launch opportunities for the propellant launches to dock with the orbiting EDS.  Passive boil-off measures can reduce boil-off rates to ~0.01%/day, sufficient to support the period that the EDS is in orbit waiting to be completely filled and for the crew to arrive, see: http://www.lockheedmartin.com/data/assets/12382.pdf. Cryo transfer of propellants is not a wild, futuristic technology.  Using a settled environment, cryo transfer is very similar to what cryo stages do today: http://www.lockheedmartin.com/data/assets/12384.pdf.  The Centaur Test Bed concept is an inexpensive way to demonstrate full up cryo transfer in the next few years: http://www.lockheedmartin.com/data/assets/12534.pdf.

This approach uses the most reliable rockets to launch people and the expensive exploration elements, encourages private investment to advance the state of launch vehicles by creating a large market for launched propellant, and reduces NASA's up front investment allowing exploration sooner.  The entire launch architecture is extensible to more advanced missions such as Mars while also reducing launch costs for all other NASA, DoD and commercial endeavors.

Offline meiza

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Kayla, your links don't work for me?

Anyway, technically, docking isn't needed if you use a propellant depot that has a robot arm that can grab and berth the incoming tankers or the to-be-tanked craft.

Offline hyper_snyper

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Just delete the last period from the links.

Offline mlorrey

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Kayla - 11/6/2006  9:25 AM

Griffin:
"Many, if not most, unmanned payloads are of very high value, both for the importance of their mission, as well as in simple economic terms. The relevant question may be posed quite simplistically: What, precisely, are the precautions that we would take to safeguard a human crew that we would deliberately omit when launching, say, a billion-dollar Mars Exploration Rover (MER) mission? The answer is, of course, “none”. While we appropriately value human life very highly, the investment we make in most unmanned missions is quite sufficient to capture our full attention."

This is a good point. I'm not sure what current life insurance actuaries say a human life is worth, monetarily (and of course, the investment in training someone to be an astronaut increases that singificantly, but I recall at one time it was an average of $6.5 million per person), but with payloads themselves worth hundreds of millions, if not billions, of dollars, the idea that a rocket needs to be sufficiently more reliable to be "man rated" is ludicrous from a utilitarian standpoint: you lose as much economically by losing an expensive payload.

Financially, losing 7 astronauts at once is a loss of less than a hundred million dollars worth of payload.

Granted, this is very callously utilitarian, and many may feel that a human life is "priceless", the fact is that courts of law find the worth of a human life in jury awards for wrongful death every day.
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Offline Kayla

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mlorrey - 11/6/2006  4:59 PM

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Kayla - 11/6/2006  9:25 AM

Griffin:
"Many, if not most, unmanned payloads are of very high value, both for the importance of their mission, as well as in simple economic terms. The relevant question may be posed quite simplistically: What, precisely, are the precautions that we would take to safeguard a human crew that we would deliberately omit when launching, say, a billion-dollar Mars Exploration Rover (MER) mission? The answer is, of course, “none”. While we appropriately value human life very highly, the investment we make in most unmanned missions is quite sufficient to capture our full attention."

This is a good point. I'm not sure what current life insurance actuaries say a human life is worth, monetarily (and of course, the investment in training someone to be an astronaut increases that singificantly, but I recall at one time it was an average of $6.5 million per person), but with payloads themselves worth hundreds of millions, if not billions, of dollars, the idea that a rocket needs to be sufficiently more reliable to be "man rated" is ludicrous from a utilitarian standpoint: you lose as much economically by losing an expensive payload.

Financially, losing 7 astronauts at once is a loss of less than a hundred million dollars worth of payload.

Granted, this is very callously utilitarian, and many may feel that a human life is "priceless", the fact is that courts of law find the worth of a human life in jury awards for wrongful death every day.

As you say, callous, but than this thread is "not for the politically correct"!

The reality though is that if either the crewed mission (CLV) or launch of the other elements EDS & LSAM (CaLV) has a failure crewed exploration missions will likely be on hold for years.  With the current architecture, even a CLV launch delay resulting in too much boil-off from the EDS will result in mission failure!  You think launching is expensive, down periods hurt more.  During the already 2.5 years of shuttle recovery NASA has spent ~$12B on the shuttle, for a single launch.  Now that is expensive.

On orbit refueling could be used with the current exploration architecture to ensure that launch delays are not failures, just replenish the EDS and LSAM.  Preferably though, eliminate the CaLV and just fill the EDS and LSAM on orbit.  A propellant launch failure does not mean mission failure if one has backup launchers for the propellant.

Offline Kayla

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SMetch - 26/5/2006  11:50 AM

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Kayla - 25/5/2006  6:17 PM

The Atlas V HLV/DEC provides sufficient upper stage thrust such that the nominal ascent profile only has to be slightly further depressed to close the black zones, causing almost no performance drop off.

My memory is that accounting for the LVHM and minor other human rating modifications, the Atlas V HLV/DEC ISS performance is ~28.9 mT.


Thanks for the info

One of the ways we could save a lot of money in servicing the ISS would be to ship up a lighter CEV/SM (ISS Config) vehicle in the first place.  I’m pretty sure the Russians are not sending people up to ISS with anything heavy as the current SRB/CLV does.

One of the big problems with the SRB/CLV is the first stage only has one general power setting.  You have to add mass to hold it down.  One size never fits all.  As such they must send up a lunar configured CEV/SM to the ISS every time.

What are the ISS performance (man launch) numbers for all the entire Atlas Line?  I’m trying to match an ISS CEV/SM with another lunar architecture we are working on.

If we can get the ISS mission done with a smaller EELV utilizing the same CEV with an ISS and Lunar SM variant we could save a lot of money and time.

For the Boeing Delta Line, one core booster might be sufficient.  With less engines to go wrong this should help in the reliablilty department.


NASA dropped the high performance cryo LO2/LCH4 propulsion module for the CEV because of the need to get the CEV flying quickly.  I completely agree that if we want to use the CEV for ISS access as soon as possible following 2010 a storable propulsion module is what is needed.  However, assuming that this storable propulsion module will also work for lunar missions is significantly degrading or increasing the launch requirements for the lunar missions.

If CEV were to have a minimal storable propulsion module to support ISS missions the CEV weight would be a fraction of the 25 mT full up CEV.  This is especially true if the CEV were delivered to an ISS proximity orbit.  With the CEV (no propulsion module) weight under 10 mT: http://www.nasa.gov/pdf/140636main_ESAS_05.pdf page 223, how light could a very simple propulsion module be.  Challenge the CEV team a little and it might be able to fly on the existing Atlas V single stick vehicle:

LEO performance for the Atlas V dual engine Centaur is 11.3 mT with an estimated reliability of over 0.996.
Or for a little more performance, the Atlas Phase 1 (4 RL10’s) performance is 12.4 mT (or 13.3 mT with 6 RL10’s) with greater reliability than today’s Atlas V.

Designing this minimal ISS only propulsion module now, would free up time for NASA to develop a high performance cryo (preferably LH2 over LCH4) propulsion module for the lunar missions.

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