NASASpaceFlight.com Forum
Commercial and US Government Launch Vehicles => ULA - Delta, Atlas, Vulcan => Topic started by: newpylong on 06/12/2013 07:16 pm
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Dual Engine Centaur (DEC) completes PDR, CDR in spring 2014.
http://www.ulalaunch.com/site/pages/News.shtml#/142/
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Flash! Grrrr.
Cheers, Martin
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Reestablishing a capability developed in 1962/63.
- Ed Kyle
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Single engine RL-10 on the Centaur was cost effective for expendible vehicles launching satellites. Dual engine Centaur is required to allow depressed second stage trajectories that virtually eliminate abort black zones - a NASA requirement for commercial crew vehicles. This is not your father's dual engine Centaur since many improvements have been made since the last flights of DEC on Atlas III.
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Looking ate the Atlas V history, only once they launched with anything more powerful than a 501 or 401 to LEO, and it was a 411. For the two Molniya they used 401 and 411. For higher energy orbits the SEC has better perfomance. And given the lack of Heavy, there was really no point until crew to actually develop it.
What's going to be interesting is if they are going to use the RL10C. And if so, if they will use DEC for more than crew. Since those are "limited" will they save them by using an extra solid? A DEC against an extra solid might be only more expensive (say 5M or so), but it might lower the stress on payload significantly. Interesting times ahead.
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What are the DEC burn out g forces again? Surly twice SEC.
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Sure, but when you've already seen more than that during 1st stage, what's the problem? Dragging along an extra RL10 to GTO is a performance waste, but an -(n-1)2 is far better than an -n1 environments-wise (and performance-wise if available) taking a heavy payload to LEO. The -02 also has abort-ability.
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Antares,
Just so I am not confusing things.
Dual Engine Centaur allows a depressed launch trajectory without a drastic payload penalty which leads to a more benign abort.
But, unless they design engine out and handling the asymmetrical thrust from the start, I am not buying an abort ability that involves a single functioning RL-10.
Does anyone know if they are designing an engine out capability into the Dual Engine Centaur?
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I could've said a -0- has more abort-ability than a -1-. That's what I meant.
Published Atlas EDS papers from 2006 talked about a tumble check that could delay spacecraft sep if attitude or rates are too far off nominal. After reading that, I immediately thought of putting the same logic in the DEC start sequence where an engine-out condition would shut off the operating engine, null the rates, and then either abort or attempt a restart.
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Aah... Though, doesn't a restart require reconditioning the engine before attempting? Meaning for a LEO launch you have to wait a certain amount of time before restarting, all while flying a suborbital ballistic trajectory... Definitely brown pants time.
Besides, if the start fails, what are the chances a restart will not also fail?
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But, unless they design engine out and handling the asymmetrical thrust from the start, I am not buying an abort ability that involves a single functioning RL-10.
Does anyone know if they are designing an engine out capability into the Dual Engine Centaur?
The development testing was conducted at Innovative Engineering Solutions of Murrietta, Calif., and included liquid oxygen duct gimbal waterflow testing to validate flow characteristics, and loads testing at liquid nitrogen temperatures to determine loads and stresses, and the ability of the duct to survive the flight-like environment.
Given that is talking about gimbal testing, does that mean that this is to cope with increased gimballing required to cope with surviving an engine out?
cheers, Martin
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Why the heck didn't ULA PAO send this out as a mailed presser. *Annoyed face!*....and then they put it on that awful flash site.
Well done for finding the link. I'll still work out an article for this, such as the stage's history through to its CCiCAP role....might be a weekend article.
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Published Atlas EDS papers from 2006 talked about a tumble check that could delay spacecraft sep if attitude or rates are too far off nominal. After reading that, I immediately thought of putting the same logic in the DEC start sequence where an engine-out condition would shut off the operating engine, null the rates, and then either abort or attempt a restart.
If DEC can operate in single-engine mode, that implies that the engines can gimbal to thrust through the CofG.
Could / would the engines be started in a "splayed" config, ie pre-gimballed to point through the CofG - and if so, would that avoid tumbling if one of the engines failed to start, or under-performed? (I suspect that would result in a sideways translation [that could be steered to the required trajectory], but no tumbling?)
If both engines start OK, they'd obviously gimball to in-line.
cheers, Martin
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Dual Engine Centaur (DEC) completes PDR, CDR in spring 2014.
http://www.ulalaunch.com/site/pages/News.shtml#/142/
Thanks for the catch. Interesting...
Under Independent Research and Development (IRAD) funding, ULA is reestablishing the Dual Engine Centaur (DEC) configuration ...
Anyone know which IRAD funds paid for it, or if ongoing work (e.g., through CDR or beyond) will also use IRAD funds?