Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 11-10-2007 04:33 PM
A Delta IV Heavy launch vehicle is scheduled to launch the Northrop Grumman-built Defense Support Program (DSP-23) mission from Space Launch Complex-37B at Cape Canaveral Air Force Station, Fla., today during a launch window extending 7:39 to 9:41 p.m. CST.
The Delta IV Heavy is the largest rocket ever to be launched by the US Air Force. It is capable of launching over 50,700 pounds into low Earth orbit. The first launch of the D4H, a demonstration flight, occurred in December 2004.
At more than 230 feet tall, the D4H stands two-thirds the height of the Saturn V. At launch, its combined thrust of 1.9 million pounds takes the rocket 15 seconds to clear the tower.
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-10-2007 09:08 PM
The beautiful images by Ben Cooper seem to show the insulation on the liquid hydrogen tanks did not "burn" this time. What was the fix?
Robert Pearlman Editor
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 11-10-2007 09:19 PM
At the end of this evening's webcast, United Launch Alliance replayed the first couple of minutes of the launch without sound. For those who missed the live video, here is that playback:
cspg Member
Posts: 6210 From: Geneva, Switzerland Registered: May 2006
posted 11-11-2007 12:19 AM
Robert,
I didn't see the launch "live" hence my question: is this video in slow motion? It seems that the rocket takes an awful "long" time to clear the tower- if you compare it to Ariane 5, Delta 2s and Shuttle (because of lack of SRBs?). Such "slow" liftoff seems uncommon, at least to me.
Chris.
LCDR Scott Schneeweis New Member
Posts: From: Registered:
posted 11-11-2007 08:51 AM
Direct TV had a High Def airing of the launch on HDNET last night...pretty spectacular and nice to see a LH2/LOX propelled liftoff again
Posts: 42988 From: Houston, TX Registered: Nov 1999
posted 11-11-2007 09:01 AM
quote:Originally posted by cspg: It seems that the rocket takes an awful "long" time to clear the tower...
As noted in my first post above, it takes more than 15 seconds for the Delta IV Heavy to clear the tower. To quote Spaceflight Now:
quote:It all begins with 1.9 million pounds of thrust powering the Delta 4-Heavy rocket ever so slowly off the ground, taking more than 15 seconds for the vehicle to clear the launch pad tower on three pillars of flame from the hydrogen-fueled engines.
hlbjr Member
Posts: 475 From: Delray Beach Florida USA Registered: Mar 2006
posted 11-11-2007 09:05 AM
I drove up for the launch last night from Delray Beach. Conditions were perfect with a cool clear star-filled sky. I watched from the jetty at Port Canaveral. The sound and view were better than I had hoped. Those RS-68's put on one heck of a show and we could easily track the booster through separation of the 2 core boosters through to stage 1 separation. We could actually hear rumbling from the engines for minutes after the launch. We couldn't quite figure that one out but we weren't complaining! Just spectacular.
Harvey Brown
art540 Member
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-11-2007 09:38 AM
quote:Originally posted by cspg: Is this video in slow motion?
Chris: note the speeds of the exhaust to the right just after ignition. YouTube does seem a little slower than Spaceflight Now video?
cspg Member
Posts: 6210 From: Geneva, Switzerland Registered: May 2006
posted 11-11-2007 10:33 AM
quote:Originally posted by Robert Pearlman: As noted in my first post above, it takes more than 15 seconds for the Delta IV Heavy to clear the tower.
oooooops! Missed that in your post!
quote:Originally posted by art540: YouTube does seem a little slower than Spaceflight Now video?
I don't know about Spaceflight Now but if the video starts at main engine ignition, the rocket takes almost 30 seconds to clear the tower/lightning masts.
Chris.
Philip Member
Posts: 5952 From: Brussels, Belgium Registered: Jan 2001
Posts: 1896 From: Cape Canaveral, FL Registered: May 2000
posted 11-12-2007 03:54 PM
Yea that video is slow motion for some reason. This D4H was a little faster than the first; the payload weighed only 5,000 lbs versus about 10k on the demo launch.
art540 Member
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-12-2007 07:07 PM
I have noticed that before Delta 4 igntion the lox tanks on all 3 cores are white in appearance but at liftoff they are now orange to match with the liquid hydrogen tanks. Any explanation for this? Prelaunch prep shows as orange.
Ben: do your stills just before ignition show this? or is all your equipment sound activated?
Art LeBrun
LCDR Scott Schneeweis New Member
Posts: From: Registered:
posted 11-12-2007 07:19 PM
That is cryogenic slush/ice coating the exterior of the tanks..it is melted by deflected thrust upon engine ignition ..
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-12-2007 07:31 PM
Ice sounds reasonable but I believe the orange is insulation so ice would not show. if ice it seems to "go away" too quickly and cleanly via heat and pressure.
Ben Member
Posts: 1896 From: Cape Canaveral, FL Registered: May 2000
posted 11-12-2007 07:53 PM
It is indeed ice; or frost. It flies off or melts as soon as ignition takes place. You can sometimes see 'glitter' around the rocket in some photos.
You can indeed see it change in my images:
This versus this just a few seconds later shows how it quickly disappears.
The foam is essentially the same as the shuttle's, and ice/frost sometimes forms on the ET as well.
art540 Member
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-12-2007 07:58 PM
I stand corrected and thank you, Ben and Scott. It just seemed so uniform in the abrupt change and the "glitter" was very obvious. Now what about the huge "flame" at ignition? A lead in flow of one propellant?
Art LeBrun
LCDR Scott Schneeweis New Member
Posts: From: Registered:
posted 11-13-2007 06:17 AM
Yes..just prior to RS-68 ignition propellant is flowed through the engine injectors and turbopumps. The LH2 undergoes a phase transition to gas after venting through the injectors/turbopump exhausts and during the brief period prior to engine ignition accumulated in and around the engine. The Shuttle launch pad has pyrotechnics fired up just prior to SSME light-off to address this, but I don't believe thats the case on the USAF launch facility.
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-13-2007 06:57 AM
Thank you, Scott. The flow is probably for the chilldown of the RS-68 but what an accumulation. I have noticed a gas burnoff pipe nearby similar to gasoline refineries. I need to find a source for additional Delta 4 tech data beyond the sparse ULA public releases.
Ben Member
Posts: 1896 From: Cape Canaveral, FL Registered: May 2000
posted 11-13-2007 06:58 AM
Actually, the Delta 4 pad does have ROFI sparklers that are fired at T-11 seconds to burn off excess hydrogen gas just as the shuttle does.
The fireball is caused by what I believe art is correct in describing as a lead flow in hydrogen; hydrogen is 'dumped' from the engines just before they mix and ignite.
I do not fully understand why this is safer than the gas which needs to be burned off.
LCDR Scott Schneeweis New Member
Posts: From: Registered:
posted 11-13-2007 07:24 AM
quote:Originally posted by art540: I have noticed a gas burnoff pipe nearby similar to gasoline refineries.
This is likely for gaseous hydrogen being released by and diverted from vent/relief valves on the launch vehicle LH2 tank
art540 Member
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-13-2007 11:12 AM
Interesting differences on liquid hydrogen venting - the Atlas-Centaur pads at the Cape and VAFB had tall vent pipes leading up from the umbilical tower. The Centaur stage had a small extended vent pipe for hydrogen vented at low altitudes. Ben: do you have any images of the Delta 4 Heavy ground vent pipe that is shown burning off gas? Must be for safety reasons - seems complex?
Ben Member
Posts: 1896 From: Cape Canaveral, FL Registered: May 2000
posted 11-13-2007 12:27 PM
You mean this flame in front of my camera :-)
And yea I think it burns off H2 from the storage tanks at the pad, rather than the rocket itself. It is located right next to the H2 sphere.
art540 Member
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-13-2007 12:44 PM
That is the one... I was hoping for a dayllght image - sorta of a ground support view of the pad area. Interesting that would be for the hydrogen storage tank. It did seem too far away to be for the vehicle!
Thanks for all your input, Ben.
Art LeBrun
Ben Member
Posts: 1896 From: Cape Canaveral, FL Registered: May 2000
posted 11-13-2007 03:31 PM
I think it is almost invisible in the daytime. I have one video of a daytime D4 launch here that shows it and all you can see is smoke coming out of it. Hydrogen flames are interesting that way. Very transparent.
art540 Member
Posts: 432 From: Orange, California USA Registered: Sep 2006
posted 11-13-2007 05:27 PM
Alcohol fuel is also transparent. Thanks to both Scott and Ben for my Delta 4 Heavy education this past week.
posted 11-10-2007 04:33 PM
advertisement