Author Topic: Launching the ITS Rocket  (Read 28530 times)

Offline envy887

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Re: Launching the ITS Rocket
« Reply #80 on: 01/09/2017 06:03 pm »

Are there other examples of a human-rated LV failing during ascent?

The point is that Challenger is not a relevant example for abort reaction time requirements.

AMOS-6 is basely a design point.

Using Raptors to escape rapidly developing failures is a terrible idea anyway. 3 seconds (or even 1 second) is an eternity if the vehicle is breaking up around you at supersonic speeds. Even deflagrating on the launch pad, like AMOS-6, happens at faster time scales.

Offline dglow

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Re: Launching the ITS Rocket
« Reply #81 on: 01/09/2017 08:39 pm »
Seems like the best option would be to launch ITS uncrewed and bring up the crew and passengers on a different vehicle after it's been refueled.
Safest option but it makes each seat more expensive. They need to address LAS, which may require detachable lifeboat section with multiple Super Dracos or SRBs.

Certainly for initial ITS missions with 10-12 crew-members, a pair of Dragon launches is reasonable. Tanker fueling can take place at a leisurely pace with the crew arriving just before departure. ITS lifting and loading would be well-proven out before launching with crew on-board.

Offline meekGee

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Re: Launching the ITS Rocket
« Reply #82 on: 01/10/2017 12:04 am »
I can't see BFS aborting during the initial launch, but I can see it escaping after some velocity is achieved, since the carnage from the failing BFR is being blown backwards.

It would help if the BFR has a strong ballistic plate up top, to protect the BFS from debris.

Looking at how the F9 failed, this was a very benign "explosion" , and would have been relatively harmless if traveling at even a few hundred MPH.
ABCD - Always Be Counting Down

Offline gospacex

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Re: Launching the ITS Rocket
« Reply #83 on: 01/10/2017 03:00 am »
The maximum yeild of a Saturn V pad explosion was estimated to be around half a kiloton, with the greatest destructive potential centered in the SII stages large tanks of hydrogen and oxygen. It would have completely destroyed the pad.

This is comparing apples to oranges. An 0.5 kiloton tactical nuke would release almost all of its energy in nanoseconds. A chemical rocket, OTOH, requires much more time for molecules of fuel and oxidizer to find each other and burn. The shock wave from the nuke would be very high pressure. The exploding chemical rocket will release its energy over a time span that is thousands or even millions of times longer. Comparing these two events is not very revealing.

Fission reaction in a nuke takes about one microsecond to complete. Fusion burn is much faster still - ~20 nanoseconds. So yes, liquid rocket explosion is many millions of times longer than these timescales.

Offline philw1776

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Re: Launching the ITS Rocket
« Reply #84 on: 01/10/2017 07:23 pm »
I am a space fan, for anyone getting anything space related done and achieved.  That being said, I think ITS is too large a leap currently.  The explorers and settlers who came to America, came in small sailing ships.  We didn't have ocean liners and container cargo ships then.

I was hoping the BFR or ITS rocket would be around 12 million lbs thrust so it could be launched from the cape and/or other areas practically.  The river and inter-coastal waterway system can handle a maximum of 12m in diameter rockets (old NOVA size from the 60's).  Pads 39a and 39b were designed to handle about 12 million lbs thrust Saturn and Nova sized rockets.  No new massive infrastructure would have to be built.  So you only get 50 tons to Mars instead of 100 tons, or 50 colonists per flight vs 100.  This might be the Mini BFR range that other threads talked about or slightly larger. 

Think of the size of the ships coming to America.  They carried only about 50 passengers each voyage.  They also depended on the mother countries for tools and equipment early on, even some food, until America became self sufficient. 

Seems to me ITS will have to have a complete new infrasture built, possibly off shore because of its shear size and danger. 

Just MHO.

Well, the BFR/BFS wasn't made the way I design simulated it either.   :'(     I feel your pain.

Correct me historians, but I thought size of the ships carrying the colonists arriving at Plymouth MA were 100 per ship, not 50.

Mars colony will depend on Earth for tools, equipment for many synods.  Plus enough Earth food to last a synod in case of agri-disaster.

I don't see the difference that's bothering you.

A heavier tonnage to Mars surface means lots of equipment, tools and spares.

As to off shore launch for BFR, I've been in that camp from day one, especially from Boca.  Shallow seas.
« Last Edit: 01/10/2017 07:24 pm by philw1776 »
FULL SEND!!!!

Offline Almurray1958

Re: Launching the ITS Rocket
« Reply #85 on: 01/10/2017 07:44 pm »
"Correct me historians, but I thought size of the ships carrying the colonists arriving at Plymouth MA were 100 per ship, not 50."


102 passengers, aprox 30 crew.
- Al Murray

Offline deltaV

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Re: Launching the ITS Rocket
« Reply #86 on: 01/19/2017 04:01 am »
Using Raptors to escape rapidly developing failures is a terrible idea anyway. 3 seconds (or even 1 second) is an eternity if the vehicle is breaking up around you at supersonic speeds. Even deflagrating on the launch pad, like AMOS-6, happens at faster time scales.

Would Raptors be usable for abort if they were pressure-fed (during aborts) instead of using turbo-pumps?

Offline envy887

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Re: Launching the ITS Rocket
« Reply #87 on: 01/19/2017 12:36 pm »
Using Raptors to escape rapidly developing failures is a terrible idea anyway. 3 seconds (or even 1 second) is an eternity if the vehicle is breaking up around you at supersonic speeds. Even deflagrating on the launch pad, like AMOS-6, happens at faster time scales.

Would Raptors be usable for abort if they were pressure-fed (during aborts) instead of using turbo-pumps?

No. Operating pressure is WAY too high for pressure-fed, thrust of 9 engines is too low for pad abort even when turbo-pumped, and the vac nozzles would flow sep at sea level causing even lower thrust and control instabilities.

There's no feasible way to generate enough thrust to abort 2,000+ tonnes off the pad at any reasonable speed.

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