Delta 4-Heavy: success in doubt

[rocketwatcher2001]

(3?)<br /><br />Than I'm all messed up on what a common core booster is.<br /><br />Isn't it where the core and the booster have the same engines? <br /><br />Delta IV heavy is the only I can think of. <div class="Discussion_UserSignature"> </div>

 

[padrat]

>>Than I'm all messed up on what a common core booster is. <<<br /><br />A common core booster (CCB) is what Lockheed Martin calls their Atlas V first stage. A common booster core (CBC) is what Boeing calls their Delta IV first stage.<br /><br /> />>Isn't it where the core and the booster have the same engines? <<<br /><br />"Booster" is the generic term usually applied to the first stage of a rocket. LockMart and Boeing call their boosters "Core" because it serves as the core of all their variants. Their Heavy variants are made up of three "cores" attached side by side.<br /><br />-Pad Rat-

 

[mikejz]

I can understand the need to monitor fuel consumption on the two boosters--but what is the logic of even having a shut down of the center stage, just run it until the engine stops developing thrust, then stage. <br /><br />(I bet there is a answer as to why......)

 

[padrat]

>>I can understand the need to monitor fuel consumption on the two boosters--but what is the logic of even having a shut down of the center stage, just run it until the engine stops developing thrust, then stage.<<<br /><br />Running an engine until one or the other of its propellants exhausts is unwise. It leads to unstable combustion, pump turbine overspeed and possible disintegration of the turbine. Those events could have a drastic effect on the vehicle's stability.<br /><br />-Pad Rat-

 

[drwayne]

A flow sensor probably saved Apollo 13 from tearing itself apart. Towards the end of second stage flight, the center engine experienced particularly violent POGO, and it was basically going to tear itself off the rails. The sensor detected the oscillating flow, and shut the engine down.<br /><br />You might find this interesting reading:<br />http://yarchive.net/space/rocket/pogo.html<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[rocketwatcher2001]

Thanks Padrat.<br /><br />I was under the impression that "common core" was a configuation, rather than a piece of equipment. <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

That's a reasonable impression to get, though. After all, Atlas V uses the same philosophy.<br /><br />Basically, the common (core) booster (core) philsophy lets them greatly reduce the cost of a heavy-lift rocket. Normally, these rockets are so hideously expensive because there is virtually no market for them, outside of military launches and the occasionally heavy deep space probe (although there hasn't been one of those since Cassini, due to efforts to reduce spending within NASA). So the cost of the rocket is defrayed by the fact that its major components are identical to those used for more typical medium-lift launches. Both Lockheed and Boeing have subscribed to the philosophy, which is a cornerstone of the USAF's Evolved Expendable Launch Vehicle program. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mikejz]

I'm not so sure about that whole cost cutting idea in practice. After all Cassini's ride only cost about $400 million, which made up only about 10-15 precent of its overall cost. Assume the same cost model for the mil birds, and Its hard to take pride in reducing the launch cost by half if that cost only makes up a fraction of a total missions cost.

 

[mrmorris]

<font color="yellow">" Its hard to take pride in reducing the launch cost by half if that cost only makes up a fraction of a total missions cost. "</font><br /><br />Well -- one theory is that a significant reason why the satellites/probes cost so much is that they are massively overengineered <b>because</b> the boosters cost so much. If you're going to sink 400 million into the booster alone -- spending 8-10 times that much to make sure the satelllite/probe is triply redundant makes some sense. A reduction of 50% in the price of the booster then has the <b>potential</b> at least to induce comparable reductions in the price of the payload being launched.<br /><br />We'll just have to wait until launch costs drop by 50% to see if this theory holds any water... <img src="/images/icons/smile.gif" />

 

[spacester]

Right. And of course it has been cogently argued that the reason the launch costs remain high is a low flight rate.<br /><br />C'mon, Falcon V! Go SpaceX! <div class="Discussion_UserSignature"> </div>

 

[mikejz]

I don't completely agree. After all in Lunar Prospector the Athena 2 was only 35% of total mission cost, and it seems that that mission is the benchmark for simple design. <br /><br />They key does not seem to be the weight-saving mentality, instead of an overall design philosophy that results in missions costing more than the vehicle that gets them into space. After all, plenty of Billion $ missions have flown on Delta IIs and Atlases. I mean from my understanding the current low price for space access is something near $3,600/lb for an Atlas V 401. <br />

 

[najab]

And, to complete the set of arguments, it is usually said that rockets are so expensive because they have to be 6 9's reliable - because the payloads cost so much.

 

[nacnud]

Time to plug the seadragon concept maybe... ... again.

 

[spacester]

So I'm not the only one who wonders how many times we've had this discussion before . . . <div class="Discussion_UserSignature"> </div>

 

[najab]

It's worse than a circular argument, it's a polygonal argument! There's at least 5 arguments and they all lead back to "It costs as much as it does because that's how much it has always cost."

 

[spacester]

Well said. <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

Hey padrat, a belated congrats on getting the scoop with the propellant flow/sensor problem. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><em><font size="2" color="#ff0000">Who is this superhero?  Henry, the mild-mannered janitor ... could be!</font></em></p><p><em><font size="2">-------------------------------------------------------------------------------------------</font></em></p><p><font size="5">Bring Back The Black!</font></p> </div>

 

[halman]

najaB,<br /><br />It seems to me that the unit costs of boosters would come down markedly if we built them assembly-line fashion. I realize that there is not enough demand to justify such production methods, but boosters can be stored for several years without any problem, if they are prepared properly. Instead of building them one at a time, we should build 25 on a production run, with primary avionics, pumps, and other essential hardware, and then add strap-on boosters, specialized avionics, etc., when preparing for a given mission. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[najab]

The Detla CBCs are built on an assembly line. The Boeing plant in Decatur has the capability to build about 40 per year.

 

[mikejz]

40/year<br /><br />Someone needs to teach Boeing about some supply and demand!

 

[najab]

Remember that the development of the Delta-4 started before the bottom fell out of the launch market.

 

[spacester]

<font color="yellow">40/year <br /><br />Someone needs to teach Boeing about some supply and demand! </font><br /><br />I agree. Before too long, we're going to need a lot more than 40 CBCs a year. <img src="/images/icons/laugh.gif" /> <img src="/images/icons/laugh.gif" /> <img src="/images/icons/wink.gif" /><br /><br />But first, someone is going to have to teach Wall Street that space enterprises work. The problem is not oversupply per se, it's lack of demand. (IMHO)<br /> <div class="Discussion_UserSignature"> </div>

 

[najab]

From the article:<blockquote>The Air Force had planned to fly the first operational Delta 4-Heavy rocket in the August-September time frame to deploy the final Defense Support Program missile warning satellite. What, if any, delay this launch could encounter remains unknown.</blockquote><p>Hmm...you don't think they'll do another test flight, do ya? <img src="/images/icons/laugh.gif" /></p>

 

[mikejz]

Ummm...Another Test....<br /><br />Maybe I should get to work in the garage and try my hand at DIY satellite construction.

 

[propforce]

Update from Space Flight Now <br /><br />Experts using computer simulations in Delta 4 probe<br />BY JUSTIN RAY <mailto:justin@spaceflightnow.com /><br />SPACEFLIGHT NOW<br />Posted: January 30, 2005<br /><br /><br />CAPE CANAVERAL, Fla. - While complex computer simulations are being run to understand what interrupted its main engines from finishing their firings, the entire six-hour maiden flight of the Boeing Delta 4-Heavy rocket was examined in deep detail last week as part of a planned post-mission review. <br /><br />The flight data review was extremely thorough, scrutinizing not only the extensive, standard flight telemetry data, but also the additional data from more than 500 channels of special instrumentation, specifically installed for this first Heavy mission," said Col. John Insprucker, Evolved Expendable Launch Vehicle Program Director at the Air Force's Space and Missile Systems Center. <br /><br />Officials sifted through mounds of data collected from liftoff through deployment of the mock satellite cargo during the Air Force-ordered test launch. The Defense Department awarded Boeing a $141 million contract to fly the first Delta 4-Heavy on a demonstration launch instead of carrying a real payload. <br /><br />"It's important to remember that the primary payload for this mission was really the instrumentation we carried onboard," Col. Insprucker said. "Our investment in telemetry and additional special instrumentation is helping us quickly zero in on the cause of the anomaly, and I'm confident the data will also enable us to fine-tune all aspects of our future Delta 4 heavy-lift missions." <br /><br />The December 21 flight was deemed a success despite a problem impacting the firing time of all three Common Booster Cores, which were strapped together to form the rocket's first stage. The Rocketdyne-made RS-68 main engine on each booster shut down several seconds early, causing <div class="Discussion_UserSignature"> </div>