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samkent
2009-Mar-09, 06:01 PM
Could someone give a good explaination and resons for. I have seen it mentioned before but there is little on the www concerning it.

NEOWatcher
2009-Mar-09, 06:14 PM
Could someone give a good explaination and resons for. I have seen it mentioned before but there is little on the www concerning it.
We must search differently... The Black Zones (http://wiki.nasa.gov/cm/blog/waynehalesblog/posts/post_1226607027430.html)

I had some inkling on what it could be, but wanted to learn more. I did know at least that it wasn't the emotional state of the liftoff.

hhEb09'1
2009-Mar-09, 06:44 PM
We must search differently... The Black Zones (http://wiki.nasa.gov/cm/blog/waynehalesblog/posts/post_1226607027430.html)
Of course, reading that, "depressed trajectories" result in elimination of "black zones"

NEOWatcher
2009-Mar-09, 07:20 PM
Of course, reading that, "depressed trajectories" result in elimination of "black zones"
Yes; is there another reason?

In the context of where I think this question came from, the discussion was about a booster designed for cargo being used for a crew capsule. My guess is that the black zone is the reason for this distinction in that case.

01101001
2009-Mar-09, 09:46 PM
This sounds like a job for Zoloft!

Ilya
2009-Mar-10, 02:31 AM
Could someone give a good explaination and resons for. I have seen it mentioned before but there is little on the www concerning it.

The only use for depressed trajectory I know of is for an intermediate-range missile to reach target faster than it would on a simple ballistic trajectory.

publiusr
2009-Mar-13, 08:30 PM
That was the case with their TOPOL solid. But there is more to depressed trajectory than that. EELVs were made for milsats/comsats. Depresed trajectory is simply better for launching men to LEO. EELVs are for higher orbiting assets.

More some highlights from Keith Cowing's great site. (We don't see eye to eye--but he does have a good grasp on the inside)


Quote
'The EELVs (Delta IV in particular)were found to fly highly lofted trajectories which would subject the crew to unacceptably high G loads following an abort. Also, the EELVs currently flying don't meet Constellation requirements. An EELV-derived vehicle for Constellation would be a new development just as Ares I is, and if chosen, it would now be having its own development problems that people would be griping about in this forum.

"Ares I/Orion's low-to-negative mass reserves"

Not true. Not according to the latest performance reports I've seen.

"lack of redundant systems"

The electronics designs I've seen show plenty of redundancy. Maybe you're talking about propulsion, but no launch vehicle is fully redundant in propulsion.

"barely tolerable thrust oscillation"

From a technical viewpoint, thrust oscillation is a very solvable problem with a number of possible solutions. The biggest issue is the cost and schedule impacts required to solve it.

"flight control issues"

What flight control issues? What program documentation have you been reading that cites flight control issues?

"continued design instability"

Okay, thrust oscillation forced a delta PDR. Other than that, I haven't seen anything other than normal maturation of the design. What continued instability do you mean?


ALSO IN DEFENSE OF CONSTELLATION/ATK


"The statement about the lofted trajectories comes not only from the ESAS study itself, but from a trajectory engineer whom I have known for a number of years and trust implicitly. Not a myth, but engineering analysis."

"Also, if you examine the Delta 4 and Atlas 5 planners' guides and compare the stated capabilities against the requirements levied on Ares I in the Constellation Architecture Requirements Document (CARD), it would be glaringly obvious to you that none of the currently flying EELV models meet the CARD requirements for payload to orbit or compatibility with Orion."

"The CARD requires the Ares I LOM to be no worse than 1 in 500. Ares I isn't quite doing that well, yet, but it's better than 1 in 400. 0.95 (1 in 20) doesn't cut it."

--------------------Posted by: Tiny Cog in CxP Wheel at March 2, 2009 10:53 PM


************************************************** ***************
-------------------------------------------------------------------------------__________________________________________________ ____________________

Could the EELV pushers be attacking this man unfairly?
http://www.nasawatch.com/archives/2009/03/former_nasa_chi.html

Another highlight quote from a response to the above article

"I'm getting a feeling there is an on-going effort from certain DoD contractor circles to offload their projects (and funding source) onto NASA before huge budget cuts eliminate their funding lines within the DoD."

"It's simple math,

DoD budget in 2001: ~$280 billion

DoD budget in 2009: ~$500 billion (excluding additional appropriations to fund the wars)."

"When the DoD has a budget higher than the rest of the planet combined, and we're in the middle of a huge economic crisis, something's gotta give. It's clear to me that DoD space is the lowest priority at a time the Air Force has to urgently replace most of its aging inventory, the Army needs a massive recapitalization, and the Navy is feeling the crunch in trying to replacing aging Ticonderoga cruisers and to pushing ahead with a new generation of carriers."

MORE----------------------

"The move is quite apparent, especially in discussions regarding the creation of the National Space Council, its charter, and names that have been floating around for that post. Also, one has to be really naive in 'DC affairs' to believe the people whose names are being circulated are not actively pursuing the post. The move is not just limited to offloading much of EELV cost onto NASA, but also many other satellite programs and supporting infrastructure the DoD wants others footing the bill."

"Military space has value, of course, but going from $500 to $300 billion is a significant 40% cut someone has to make after carefully reviewing the return on investment for each program. With the Cold War over, and myriad of low-tech enemies we're fighting around the globe, the actual multiplying effect in much of 'military space' is debatable."

"Is there a relation with this case? I hope not, but I do get annoyed how little time it takes certain circles to do their own spinning and poke NASA at every turn. I know because I hear and see these things, in person, over and over."

Posted by: Lowly Contractor at March 8, 2009 3:14 PM


Other remarks........................................... .....


"I've a hunch this is what is behind the sudden urge to offload EELVs to NASA, wanting to force international satellite operators to use U.S. launchers even for non-ITAR satellites, the parade of former DoD generals wanting to be NASA administrator, the talk of 'inefficiencies' in space always pointing the finger at NASA but never the DoD, and a long list of etc."

"Whatever the facts of this case are, we are talking peanuts compared to the billions upon billions wasted elsewhere. I'm now wondering whether part of the delay in appointing a NASA Administrator is the Obama Administration coming to realize certain advice it's been getting has other special interests in mind."

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$

And I finish things nicely--defending Mr. Stadd--in reminding who is REALLY guilty

"To Refresh your memory, people.

http://www.defenselink.mil/releases/...releaseid=5539

http://www.usdoj.gov/criminal/cyberc...anchCharge.htm "

They used to work for Boeing, not ATK

publiusr
2009-Mar-13, 09:07 PM
Something else to consider

In light of this article--
http://www.spaceflightnow.com/news/n0901/14dsp23/

---Some of the push for a smaller Orion that might have a higher orbit smacks of the Blue Gemini Deep Cold sat-inspector craft.

A larger Ares I launched Orion is great for ISS and exploration--though less suited for the military. By nixing Ares, money could be spent developing a device for messing with other nations space assets. There were already designs for cold gas thrusters for OSP--that became CEV--that became Orion.

Shrink a cold gas equipped Orion down--put it atop a D-IV heavy---and have it go after higher orbiting satellites for other nations
http://www.c4isrjournal.com/story.php?F=2034471

Naturally a smaller Orion capsule would be less noticable. You wouldn't want the original Orions big solar array pair that exploration needs.

So if you want a gutted NASA suited to help Air Force needs and remember the Deep Cold Blue Gemini/ASSET days--well...that would be telling, #6.

I do remember a recent commercial for the Air Force that had a tiny station (MOL sized) that seemed rather high up. Now maybe that was just some SPFX artists coming up with a general design to boost the wow-factor for recruiting. Still....

I think Obama is being fooled. He thinks the USAF is trying to help--where I think they are trying to hurt. Griffin might not have been your ideal Chief--but he wanted an INDEPENDANT NASA. Good for him.


At least we have some folks who want a strong NASA.
http://www.nasawatch.com/archives/2009/03/bill_nelson_con.html

Here I explain why EELVs are dangerous not only to astronauts--but to NASA's very future.
http://www.bautforum.com/space-exploration/83512-new-nasa-chief-2.html#post1453433

djellison
2009-Mar-14, 01:45 AM
At least we have some folks who want a strong NASA.

Who here doesn't.

Launch window
2009-Mar-14, 02:56 AM
and I thought this would be a thread about 'orbital altitudes' etc
is it just me or has this thread gone a bit personal?

Ilya
2009-Mar-14, 02:57 AM
Someone must feel depressed.

Sticks
2009-Mar-14, 04:58 PM
publiusr please desist from hijacking this thread into another EELV vs ARES argument

publiusr
2009-Mar-16, 06:57 PM
Hard not too seeing that the depressed trajectory that Mr. Hale talks about is what Ares I is a bit better at therefore no hijacking.

publiusr
2009-Apr-27, 08:36 PM
Could someone give a good explaination and resons for. I have seen it mentioned before but there is little on the www concerning it.

At the risk of being called a thread zombie, I would suggest the current (April/May 2009) issue of AIR & SPACE.

A quote from page 21:

"The rocket trajectory, though, must be designed so that astronauts would survive an abort. Unmanned rockets such as the Delta IV and Atlas V, which have relatively underpowered second stages, fly a 'lofted trajectory,' where the first stage shoots them very high and they actually start falling before the second stage lifts them again. If astronauts abort near the high point, their capsule could plummet straight down and belly flop on the atmosphere at extreme G force."

"'Structural safety margins will be blown to___, and you'll almost certainly kill people,"Musk says flatly. 'This was one of the main reasons given by NASA for not using those vehicles for manned spaceflight.'"

Musk's rocket has a second stage "about four times as powerful as that of an Atlas or a Delta, allowing for a more slanted, softer trajectory into space." Its structure is said to withstand flight loads 40% higher than what it is likely to encounter. Unmanned rockets have only 25% margin, or so that article tells us.

The May 2009 issue of Air & Space Smithsonian has Hoot Gibson and the shuttle on the cover, and is one of the better issues, FYI. Nice images of Musk and Falcon 9 too.