Author Topic: Human-rating F9/Dragon and SpaceX's push-based escape system  (Read 60850 times)

Online docmordrid

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #100 on: 11/28/2010 11:57 AM »
Fuels are nitrogen tetroxide and monomethyl hydrazine. 

Combustion products should pretty much limited to nitrogen oxides, carbon monoxide, carbon dioxide, and nitrogen - most of which come out of a pre-catalytic converter cars tailpipe.
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Offline Jim

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #101 on: 11/28/2010 12:30 PM »
Fuels are nitrogen tetroxide and monomethyl hydrazine. 

Combustion products should pretty much limited to nitrogen oxides, carbon monoxide, carbon dioxide, and nitrogen - most of which come out of a pre-catalytic converter cars tailpipe.


there is always residual N2O4 and MMH in the exhaust for various reasons, some of which are:

1. fuel or ox lead or lag for thruster cooling
2. fuel or ox for chamber film cooling
3. fuel or ox lead or lag for combustion stability
4. valve leaks
5. residuals from incomplete combustion

Offline Ben the Space Brit

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #102 on: 11/28/2010 03:16 PM »
I doubt that the concentration of toxic chemicals would be very high.  Remember, this is going to happen in the open air and will be followed almost immediately by the air displacement of the capsule touching down.

I would imagine that initial side decontam by guys in chemical protection suits and using steam jets would be sufficient to clear any remaining nasties.
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Offline Jim

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #103 on: 11/28/2010 03:34 PM »
I doubt that the concentration of toxic chemicals would be very high.  Remember, this is going to happen in the open air and will be followed almost immediately by the air displacement of the capsule touching down.

I would imagine that initial side decontam by guys in chemical protection suits and using steam jets would be sufficient to clear any remaining nasties.

not denying that it can't be taken care of, see sniffers, wind machine and SCAPE suits at shuttle landing.   All this means is $$$.  And also, a facility close by (within the limits of the landing range) to offload the propellants.

Offline rsnellenberger

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #104 on: 11/28/2010 05:49 PM »
I doubt that the concentration of toxic chemicals would be very high.  Remember, this is going to happen in the open air and will be followed almost immediately by the air displacement of the capsule touching down.

I would imagine that initial side decontam by guys in chemical protection suits and using steam jets would be sufficient to clear any remaining nasties.

not denying that it can't be taken care of, see sniffers, wind machine and SCAPE suits at shuttle landing.   All this means is $$$.  And also, a facility close by (within the limits of the landing range) to offload the propellants.
To a lesser extent, both Gemini and Apollo had a similar environment after landing and the only time they had a problem with it (that I can recall) was at the end of the Apollo 13 mission when a vent opened prematurely and allowed exhaust gases to get into the capsule right after landing.

Offline Jorge

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #105 on: 11/28/2010 05:55 PM »
I doubt that the concentration of toxic chemicals would be very high.  Remember, this is going to happen in the open air and will be followed almost immediately by the air displacement of the capsule touching down.

I would imagine that initial side decontam by guys in chemical protection suits and using steam jets would be sufficient to clear any remaining nasties.

not denying that it can't be taken care of, see sniffers, wind machine and SCAPE suits at shuttle landing.   All this means is $$$.  And also, a facility close by (within the limits of the landing range) to offload the propellants.
To a lesser extent, both Gemini and Apollo had a similar environment after landing and the only time they had a problem with it (that I can recall) was at the end of the Apollo 13 mission when a vent opened prematurely and allowed exhaust gases to get into the capsule right after landing.

That was ASTP, not Apollo 13.
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Offline AS-503

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #106 on: 11/28/2010 06:01 PM »
Apollo Soyuz Test Project had an issue with potentially fatal levels of n2o4 and hydrazine.

The crew reportedly left the RCS on the during the entire descent. This exhaust was then sucked into the Apollo capsule at the time of pressure equalization.

What kind of emergency breathing apparatus did the Apollo crew how for this type of issue?

The Navy recovery divers for Apollo had what looked like gas masks.

Any thoughts, Jim, Jorge?

Offline AS-503

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #107 on: 11/28/2010 06:14 PM »
With regard to ASTP (sorry for the OT content).

Leonov had a good sense of humor and broken english.
He liked to rib Tom Stafford about stuff.
I can hear him joke, "Tom Stafford left switch on...Tom Stafford not want should do this."

See Leonov's comments about his visit to Hollywood.


Offline Patchouli

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #108 on: 11/28/2010 08:04 PM »
I doubt that the concentration of toxic chemicals would be very high.  Remember, this is going to happen in the open air and will be followed almost immediately by the air displacement of the capsule touching down.

I would imagine that initial side decontam by guys in chemical protection suits and using steam jets would be sufficient to clear any remaining nasties.

not denying that it can't be taken care of, see sniffers, wind machine and SCAPE suits at shuttle landing.   All this means is $$$.  And also, a facility close by (within the limits of the landing range) to offload the propellants.
To a lesser extent, both Gemini and Apollo had a similar environment after landing and the only time they had a problem with it (that I can recall) was at the end of the Apollo 13 mission when a vent opened prematurely and allowed exhaust gases to get into the capsule right after landing.

That was ASTP, not Apollo 13.

Dragon has a 1ATM atmosphere so it probably would not need to perform much of a pressure equalization as Apollo.
It probably could even be deferred until it's time to exit the vehicle or even make use of internally stored gases vs a simple vent.
Having the capsule at a very slight positive pressure during landing probably would help a lot with avoiding contamination.

Online notsorandom

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #109 on: 11/28/2010 10:38 PM »
The next Russian space capsule has a proposed landing system which uses rockets instead of parachutes for landing. Vectorable solid rockets have been proposed for this role due to concerns over toxicity. If Dragon uses its LES during the very final stage of landing to help cushion the impact then toxicity might present some problems. Having the ground crew suit up and decontaminate the landing site could prove to take a costly amount of time if there is an emergency with one of the astronauts. Would H2O2/RP-1 be a potential nontoxic hypergolic propellant? Ultimately though we don't really know what SpaceX is planning in this regard except for a few very general statements.

Offline JayP

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #110 on: 11/29/2010 12:46 AM »
... Having the ground crew suit up and decontaminate the landing site could prove to take a costly amount of time if there is an emergency with one of the astronauts...

You know that they do that today with the shuttle? the first crews who approach are in SCAPE suits. If there was an emergency, the crash / rescue teams would go in with firesuits and OBAs under a water fog curtain from the trucks and get out everyone out as quickly as possible.

Offline butters

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #111 on: 11/29/2010 01:06 AM »
... Having the ground crew suit up and decontaminate the landing site could prove to take a costly amount of time if there is an emergency with one of the astronauts...
You know that they do that today with the shuttle? the first crews who approach are in SCAPE suits. If there was an emergency, the crash / rescue teams would go in with firesuits and OBAs under a water fog curtain from the trucks and get out everyone out as quickly as possible.

Shuttle is worse than Dragon would be, because the exhaust products of NTO/MMH bipropellant rockets are more benign than the exhaust products of the hydrazine APUs. The hypergolic rockets emit more N2 and NOx (not so bad - remote risk of asphyxiation), whereas the APUs emit more NH3 (fairly toxic).

The predominant risk of hypergolic rockets is the high toxicity of the unreacted propellants should there be a fluid leak. For example, Proton's first stage is problematic when crash-landing downrange with residual propellants. Dragon would only be a major concern if the propellant system were seriously damaged.

Offline llo2015

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #112 on: 12/06/2010 04:00 PM »
Could someone please provide pointers to the SpaceX "story" regarding crew aborts if the second-stage Merlin fails to ignite or shuts down shortly after ignition?  For most two-stage vehicles launching from Cape Canaveral and bound for an ISS rendezvous, wouldn't early second stage failure send the vehicle into the middle of the North Atlantic?  Does SpaceX deem that survivable?

Both SpaceX's Falcon-9/Dragon and NASA's canceled Ares-1/Orion launch systems use a single engine to power the second stage.  Any engine-out failure with the second stage will initiate the abort sequence for the spacecraft and presents a difficult challenge.  This is especially true for launching to the ISS from KSC/Cape Canaveral because the launch track involves the potential for a spacecraft abort into North Atlantic waters. 

NASA considers a possible engine-out event as "creditable" as there have been three occasions in the past where this has happened during Apollo/Saturn and the Space Shuttle launches.

NASA's safety standard applied to the Ares-1/Orion design requires that the any late-in-powered-flight abort must land in waters no further than 150 miles from St. Johns, Newfoundland or Shannon, Ireland.  This standard was adopted so that there was an assured presence of recovery forces within close range of landing.  The distance between these two landing zones is referred to as the North Atlantic Exclusion Zone (NAEZ).

To accomplish these abort landing constraints, the Orion Spacecraft design included the reserve propulsion capability of 1,200 Delta-V.  In addition, Orion would require about 300 Delta-V for on-orbit maneuvering in the case of an abort to orbit.  My estimate is that a 1,200 Delta V capability for a crewed Dragon spacecraft would need over 2,300 kg of propellant (N2O4/MMH).

Most likely, the imposition of the NAEZ constraint by NASA would apply to commercial crewed launched vehicles as well.  Anybody have any information how SpaceX plans to address these late-in-powered-flight abort requirements?

Offline mr. mark

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #113 on: 12/20/2010 03:09 PM »
Looking at Boeing's recent CST-100 update it seems as if they have already test fired their LAS system. How far along is Spacex with their version? I know this is where Spacex has said they need financial help. It also shows how larger companies can move ahead to meet their goals quicker relying less on government funding for certain systems. It's becoming clearer that a Boeing manned capsule MAY be available before Spacex's Dragon manned capsule.

Offline llo2015

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Re: Human-rating F9/Dragon and SpaceX's push-based escape system
« Reply #114 on: 05/07/2011 07:42 PM »
Commercial Crew Program CCT-REQ-1130

John F. Kennedy Space Center Revision: DRAFT 3.0 April 29, 2011

ISS Crew Transportation and Services Requirements

1.0        ISS Crew Transportation and Service Requirements Document

3.3        Pre-Launch/Ascent

3.3.1.7 The CTS shall provide ascent aborts that result in the spacecraft landing outside the Down-range Abort Exclusion Zone (DAEZ).

Rationale: The DAEZ is a geographical area to be avoided for landings following launch aborts due to rough seas and cold water temperature in the North Atlantic. Additionally, landing within close proximity to land masses with pre-positioned recovery teams maximizes the probability of
crew survival.

3.3.1.8 The CTS shall perform pad and ascent abort that separate the spacecraft from the launch vehicle without relying on thrust from the launch vehicle.

Rationale: Because the health of the launch vehicle cannot be guaranteed for abort situations, the spacecraft must be able to safely separate and perform ascent aborts without thrust from the launch vehicle. This does not preclude the operational use of the launch vehicle if available and desired to improve abort conditions when the launch vehicle is operating nominally

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