Delta 4-Heavy: success in doubt

[drwayne]

The Boeing Delta 4-Heavy rocket appears to have experienced lower-than-expected performance during its initial ascent today, forcing its upper stage engine to compensate and raising doubts about the mission's chances for success, sources indicate<br /><br />Rest here:<br /><br />http://www.spaceflightnow.com/delta/d310/status.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>

 

[drwayne]

I didn't see the launch...ack. <img src="/images/icons/frown.gif" /><br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[najab]

I doubt the 'Mach diamonds' were responsible, the aerodynamics of the configuration would have been tested extensively before the launch. The performance shortfall will probably be due to the extendable nozzle not extending properly or something along those lines.<p>I noticed that the first second-stage burn seemed to be longer than expected, the commentator said something like "SECO expected in 30 seconds" and it was over a minute before they confirmed the burn was completed. I thought I heard someone in the background making a comment about the engine not turning off.</p>

 

[propforce]

The CBC core burn time was cut off 30 seconds too early, therefore forcing the 2nd stage's first burn to extend longer to make up the short Delta-vee by the CBC. Now what caused that would be a subject of much interest but it's much too early to speculate.<br /><br />It is suspected that the 2nd stage burn time will be short for the 3rd burn as a result. Time will tell. <br /><br />But to all the critics in the world: THIS IS WHY YOU HAVE DUMMY PAYLOAD FOR THE FIRST LAUNCH !!! <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[steve82]

Oh No! An extendable nozzle? What's Boeing's fascination with that devil's technology, anyway? They had the same thing on the shuttle-born IUS, I think it was to allow the IUS to fit within the Shuttle Payload Bay CG limitations. If you looked at a diagram of the deployment mechanism, it sure seemed like they were pushing on rope. On the first Shuttle IUS mission, STS-6, the dang thing failed. (although I'm not sure it was the extendable part, but it sure was a busy mechanism).

 

[drwayne]

Sorry, it was not my intent in posting a link to the article to be critical.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[lunatic133]

I heard that the two nanosats launched on the dummy payload were unsuccessful -- it was sad because they were designed and built by college students, and I actually have friends who worked on the CU one. I'll bet theyre all really disappointed after all that time and work they put into it.

 

[padrat]

>>There seemed to be some 'flashing' in the plumes. Almost like Mach beads moving back and forth, like in the shots of the Shuttle engine ignition. Related?<<<br /><br />No, it's typical of all Delta IV launches. The flashing is caused by the ablative lining of the RS-68 nozzle burning off. It's supposed to do that.<br /><br /> />>I've asked this elsewhere too: was the first stage painted blue, or is that charring from the fireball at launch? <<<br /><br />That was charring caused by engine start. The west side of the booster got the worst of it because of the pad configuration.<br /><br />-Padrat-<br />

 

[CalliArcale]

If memory serves, isn't the ablative lining essentially a replacement for the age-old technique (pioneered by Von Braun's team on the V-2) of wrapping the LOX lines around the engine bell to keep it cool? It's supposed to greatly reduce weight and complexity, with the only caveat that you have to really trust that ablative material.<br /><br />Or am I thinking of a different engine? <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>

 

[CalliArcale]

BTW, apparently the USAF customer is actually pleased with the Delta IV Heavy's performance, despite the lower-than-anticipated altitude, because good data was obtained and nothing was seriously wrong. The three CBCs just shut down too quickly, and that means the problem is likely to be easy to fix. In fact, it might be a software problem, which would in many respects be the easiest to fix. <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>

 

[propforce]

The ablative is on the inside of RS-68 engine nozzle as thermal insulation instead of individual H2 cooled tubes bundled together like the SSME. This was done to reduce the manufacturing cost of RS-68. They are looking into milled channel cooling like the Russian engines for future RS-68 upgrade. <div class="Discussion_UserSignature"> </div>

 

[propforce]

<font color="yellow"><i> In fact, it might be a software problem, which would in many respects be the easiest to fix. </i></font><br /><br />No NO NO !!! AVOID SOFTWARE !! RUN FOR YOUR LIVES !!! <img src="/images/icons/shocked.gif" /><br /><br />Changing one line of code cost just about the same as rewriting the entire million lines of code. Good Grief !!! <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

 

[propforce]

Nice charred tank insulation... purdy roasty <img src="/images/icons/shocked.gif" /><br /> <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

Yes, but at least you don't have to throw away hundreds of tons of hardware. <img src="/images/icons/wink.gif" /> And the beauty of software is that once the fix is designed, implemented, and tested, you're 99% of the way to completion, whereas with hardware, you still have to manufacture it.<br /><br />I'm a software person, so I know how expensive software development can be! <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>

 

[halman]

steve82,<br /><br />There is almost always a better way to do things. Finding it can be expensive. Most street bikes don't have kick starters anymore, because battery technology advanced enough to make electric start reliable. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[propforce]

Correction, the CBCs were cutoff 8 seconds too early. <div class="Discussion_UserSignature"> </div>

 

[najab]

When you said "Armstrong starter", I thought it was a play on words for hand cranking. Armstrong - strong arms! <img src="/images/icons/laugh.gif" />

 

[najab]

Interesting. I did a Google on it, and there there <b>is</b> a company called Armstrong who makes starters - for disel engines!

 

[najab]

Is it possible that the large 'fireball' at launch is related to the performance shortfall? Looking at the launch pictures at SpaceFlightNow it is <b>really</b> impressive! I dare say a lot of LH2 went into making it.

 

[toymaker]

"Is it possible that the large 'fireball' at launch is related to the performance shortfall? "<br />To anyone that is learned in such things.Are those kind of flames normal ?

 

[propforce]

<font color="yellow"><i> "Is it possible that the large 'fireball' at launch is related to the performance shortfall? " <br />To anyone that is learned in such things.Are those kind of flames normal ? </i></font><br /><br />Yes it is normal in the case of Delta IV. Three main contributing factors are:<br /><br />1) The RS-68 engine start sequence is fuel (LH2) lead. This by itself is not unusual, as the SSME is also a fuel lead start.<br /><br />2) The Delta IV uses an enclosed exhaust duct, unlike the Shuttle that has an open exhaust trench. <br /><br />3) While the D-IV exhaust duct employs the radially outward flame igniters (ROFI), same as used on the Shuttle launch pad (the sparklers), the placement of ROFIs is more down range of the duct and apparent did little to burn off the H2 gases during normal starts. The ROFIs were designed for the case of engine abort.<br /><br />The enclosed duct (the engine section of the vehicle is <i>underneath </i> the launch table), exaggerbate the H2 lead problem as it has no where to vent but UP !!! Hydrogen is lighter than air therefore will go up rather than go down. When the engine ignited, the flame back flash to where hydrogen gases are presence, that's why you see a massive flame surrounding the vehicle.<br /><br />The range safety guys had to be specially briefed about this phenomena, so they do not press the self-destruct button as they see the vehicle is engulfed by flames <img src="/images/icons/laugh.gif" /> That would've been a very very VERY bad day if they did <img src="/images/icons/shocked.gif" />. <div class="Discussion_UserSignature"> </div>

 

[SpaceKiwi]

""The range safety guys had to be specially briefed about this phenomena, so they do not press the self-destruct button as they see the vehicle is engulfed by flames That would've been a very very VERY bad day if they did . ""<br /><br /><br />Prop,<br /><br />How dangerous is this method of venting the exhaust? To the untrained eye like mine it does seem rather "comical" that such extreme caution is taken with the flamable fuels prior to launch, yet nothing untoward is thought of engulfing the rocket in a gi-normous fireball at T-0. It seems to defy common sense even though, as SG said, a rocket is a continuous controlled explosion.<br /><br />There must surely be a statistically increased danger of "ka-boom" on launch with an enclosed exhaust duct, even if it is well within the D-IV operational safety margins? <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]

In spite of the less-that-desired performance of the Delta-IV Heavy, the Air Force put on a good face for the press, saying that the launch was a "success", (well, it didn't blow up,) and that much valuable data was collected. I am still anxious to hear the cause of the second stage having to burn for an extended time during launch. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[steve82]

"I do not think the IUS had an extendable nozzle."<br /><br />Yes it did. The extendable nozzle (called the "exit cone") was on the IUS second stage. Here's a pic of it:<br /><br /><br /><br />The also refer to it in the Payloads press release document in the IUS section:<br />[url=http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/carriers.html]http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/carriers.html<br />

 

[najab]

I know it's been a while since you've launched any, but I think it was the other way around - the IUS had one and the PAM didn't. Interesting note: remember when the abbreviation was "<i>Interim</i> Upper Stage"? It was supposed to be replaced by a space tug, but that never happened, so the <i>I</i> was changed to "Inertial" - as if other upper stages weren't about inertia too! <img src="/images/icons/laugh.gif" />