Author Topic: Ares I-X Q&A  (Read 41893 times)

Offline rdale

  • Assistant to the Chief Meteorologist
  • Senior Member
  • *****
  • Posts: 9901
  • Lansing MI
  • Liked: 247
  • Likes Given: 28
Re: Ares I-X Q&A
« Reply #20 on: 10/20/2009 03:20 PM »
Check the stories written on the homepage here.

Offline toddbronco2

  • Member
  • Full Member
  • **
  • Posts: 277
  • Pasadena, CA
  • Liked: 11
  • Likes Given: 6
Re: Ares I-X Q&A
« Reply #21 on: 10/20/2009 03:22 PM »
There's certainly nothing going into orbit from this launch.  There are actually many threads related to the Ares I-X and the apparent lack of purpose.  Ironically, even though this launch was planned years ago, it is now perfectly timed to play a role in deciding the shape of NASA's future, what with the Obama administration set to receive the final recommendations from Augustine in the coming days.  So what's the point of Ares I-X?  It might be that it's purpose is to try to save Constellation

Offline mike5770

  • Member
  • Posts: 16
  • Liked: 0
  • Likes Given: 0
Re: Ares I-X Q&A
« Reply #22 on: 10/20/2009 03:26 PM »
Thank you..I see more is on L2 I will check that out. I hope this isn't the only flight we see!

Offline sdsds

  • Senior Member
  • *****
  • Posts: 5479
  • "With peace and hope for all mankind."
  • Seattle
  • Liked: 579
  • Likes Given: 677
Re: Ares I-X Q&A
« Reply #23 on: 10/20/2009 04:45 PM »
Phrased in modern aerospace geek-speak, "What Ares-I risks are retired by successfully flying Ares-IX?"

Won't this be the first vertical firing of a shuttle RSRM unattached to an external tank?  Even though numerical modeling tells us this will work just fine,  Ares-IX will provide data about exactly how it works just fine.

The elephant in the room is solid rocket motor thrust oscillation.
-- sdsds --

Offline smith5se

Re: Ares I-X Q&A
« Reply #24 on: 10/20/2009 05:09 PM »
Ares I-X, with MLP and everything weighes 16 million lbs mentioned yesterday by PAO (ha, I'm awake this afternoon) Any idea how much less that weight is as compared to a full model Ares I would be?
My views are mine, and mine alone and DO NOT reflect that of my employer nor my place of employment.

Offline kevin-rf

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8652
  • Overlooking the path Mary's little Lamb took..
  • Liked: 1123
  • Likes Given: 243
Re: Ares I-X Q&A
« Reply #25 on: 10/20/2009 05:17 PM »
Ares-IX will provide data about exactly how it works just fine.

Assuming it works ...
If you're happy and you know it,
It's your med's!

Offline usn_skwerl

  • Space Junkie
  • Full Member
  • **
  • Posts: 218
  • Ad Astra
  • South Bend, IN
  • Liked: 0
  • Likes Given: 0
Re: Ares I-X Q&A
« Reply #26 on: 10/21/2009 03:16 AM »
This test vehicle is 200,000 lbs lighter than the production model, according to Mr. Diller last night.
If we do not destroy ourselves, we will one day venture to the stars.

Offline jcm

  • Senior Member
  • *****
  • Posts: 2957
  • Jonathan McDowell
  • Somerville, Massachusetts, USA
    • Jonathan's Space Report
  • Liked: 530
  • Likes Given: 377
Re: Ares I-X Q&A
« Reply #27 on: 10/21/2009 04:45 AM »
Maybe it's just nitpicking the definition - it may have an inclination (due east as noted above) but I don't think you can call that an orbital inclination.

Sure you can, if you were talking about a suborbital space flight. A "suborbital" flight is an orbit - it's a Keplerian ellipse which happens to intersect the atmosphere. The part of it which is outside the atmosphere can be described by the usual set of 6 Keplerian elements, including orbital inclination - it just ends up that  a(1-e) is negative.
(This is very much an astronomer's way of looking at it, of course, not a rocket engineer's).

However, Ares I-X is not only suborbital, it is endoatmospheric - it is not a space flight.
My understanding is that apogee will be only 45 km, which is technically within the stratosphere - not even the mesosphere, never mind 'space'.
So, there is no part of its flight which is truly Keplerian. But the drag at apogee is probably low enough that you could (poorly) approximate it with orbital elements. The missing value I haven't seen is the horizontal velocity at apogee. But at a rough guess, the orbital parameters, such as they are, will be around
    -6270 x 45 km x 28.5 deg

Now whether that's a *useful* description of the trajectory is a different matter. I find it helpful insofar as it gives a feel for how far the thing is from orbital, and lets me make pseudo-TLEs  that  very crudely simulate the traj with the same code I use for satellites. But it's a stretch. Once you're talking about say a Black Brant rocket flight to 300 km, or even Alan Shepard going to 180 km, the concept of orbital inclination and apogee/perigee do become much more useful, even with a very negative perigee.

Does anyone know the velocity at apogee for Ares I-X?

-----------------------------

Jonathan McDowell
http://planet4589.org

Offline Danderman

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 9621
  • Liked: 362
  • Likes Given: 464
Re: Ares I-X Q&A
« Reply #28 on: 10/21/2009 05:13 AM »
The term that everyone is grasping for here is "launch azimuth". Its useful to compare launch azimuths for orbital and suborbital flights.


Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32378
  • Cape Canaveral Spaceport
  • Liked: 11065
  • Likes Given: 329
Re: Ares I-X Q&A
« Reply #29 on: 10/21/2009 02:43 PM »
It is nothing more than a glorified admiral's test

Offline bad_astra

  • Full Member
  • ****
  • Posts: 1854
  • Liked: 245
  • Likes Given: 296
Re: Ares I-X Q&A
« Reply #30 on: 10/21/2009 03:55 PM »
$500,000,000 / 28 miles for a one-off suborbital rocket that has almost nothing in common with the production vehicle. That's not a prototype, it's a very expensive x-plane.

About $3382 per foot it's one very expensive one. At least it will get higher than X-33. Still, dollar per foot, if it flies it might be the most expensive launch vehicle ever made, since that particular vehicle design will only fly once.



"Contact Light" -Buzz Aldrin

Offline mkirk

  • International Man Of Mystery
  • Full Member
  • ****
  • Posts: 1730
  • Florida/Texas
  • Liked: 32
  • Likes Given: 0
Re: Ares I-X Q&A
« Reply #31 on: 10/21/2009 09:59 PM »
Just a little more info on the 90 degree roll maneuver/BDMs, & BTMs;

Yes, as someone posted early, the roll was necessitated by the ARES I-X orientation on the existing shuttle mobile launch platform (MLP) relative to how an operational ARES I will be oriented on its own MLP.  ARES I-X has its z-axis pointing south (i.e. capsule windows and astronauts heads would be pointed south) but the ARES I z-axis will be pointed east and the first stage systems tunnel will be facing south.

For Ares I-X, the 90 degree roll will start at ~ T+6 seconds and is intended to give the ARES I-X the same angle of attack (alpha) that an ARES I would have going uphill. 

With the I-X pad orientation, the aerodynamic protuberances – such as the first stage systems tunnel that runs along the side of the booster, are rotated 90 degrees from how the ARES I will be oriented on its mobile launch platform – by doing the roll maneuver, I-X will now have those “protuberances” orientated into the relative wind the same ways as ARES I.  Also, the 90 degree roll ensures the two exhaust nozzle gimbal actuators (known as “rock” and “tilt”) will also be oriented correctly (relative to the operational ARES I during its ascent).  If the I-X didn’t do the 90 degree roll the Ares I-X Team would have had to rewrite the guidance algorithms and flight control scheme for this flight to take into account the different orientation of the two actuators.

While it would have been possible to make those changes to the guidance and flight control system it would then mean the I-X would be LESS like the ARES I which is essentially going to use the same scheme with the rock and tilt.

Regarding the BDMs (Booster Deceleration Motors) and BTMs (Booster Tumble Motors), these are the same as the shuttle BSM (Booster Separation Motors) but there are differences in the usage on ARES I-X as compared to ARES I.  First off there will be 10 BDMs on an ARES I located on the aft skirt, ARES I-X uses 8.  Secondly, the BTMs on ARES I will be located on the forward frustum.

Mark Kirkman
Mark Kirkman

Offline USARocketMan

  • Member
  • Posts: 5
  • Liked: 0
  • Likes Given: 0
Re: Ares I-X Q&A
« Reply #32 on: 10/22/2009 12:51 AM »
The primary and secondary test objectives are posted.  Most people focus on the flight test vehicle objectives (i.e., controllability, separation systems, chute deployment & performance, etc.). It's the interesting aspect of this test to the engineer in all of us. But the other kind of objectives is the vehicle processing, ground operations, ground systems, and retrieval/recovery knowledge of working with a different kind of launch vehicle other than Shuttle. Something NASA and its Contractors haven't done in 30+ years. Significant lessons have been learned... or in some cases relearned.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32378
  • Cape Canaveral Spaceport
  • Liked: 11065
  • Likes Given: 329
Re: Ares I-X Q&A
« Reply #33 on: 10/22/2009 01:11 AM »
. But the other kind of objectives is the vehicle processing, ground operations, ground systems, and retrieval/recovery knowledge of working with a different kind of launch vehicle other than Shuttle. Something NASA and its Contractors haven't done in 30+ years. Significant lessons have been learned... or in some cases relearned.

They are not applicable to the real Ares I.   Ares I-X used mostly one time only procedures.  The SRM stacking was no different than shuttle.  The USS was built up in the transfer aisle, which is not applicable to Ares Upperstage. 

retrieval/recovery lessons could be learned for a lot less money using mockups just as was done for shuttle.

« Last Edit: 10/22/2009 01:15 AM by Chris Bergin »

Offline parham55

Re: Ares I-X Q&A
« Reply #34 on: 10/22/2009 01:30 AM »
I'm obviously missing something but why couldn't they rotate ARES I-X 90 degrees on the MLP?  I'm guessing a shuttle SRB must be mounted in a specific orientation on the MLP but why exactly?  Is it GSE, maybe something else? Thanks.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32378
  • Cape Canaveral Spaceport
  • Liked: 11065
  • Likes Given: 329
Re: Ares I-X Q&A
« Reply #35 on: 10/22/2009 01:35 AM »
I'm obviously missing something but why couldn't they rotate ARES I-X 90 degrees on the MLP?  I'm guessing a shuttle SRB must be mounted in a specific orientation on the MLP but why exactly?  Is it GSE, maybe something else? Thanks.

The hold downs are not symmetric.  There are umbilicals at the base.  The S&A needs access.

Online DaveS

  • Shuttle program observer
  • Senior Member
  • *****
  • Posts: 8020
  • Sweden
  • Liked: 466
  • Likes Given: 19
Re: Ares I-X Q&A
« Reply #36 on: 10/22/2009 02:07 AM »
The USS was built up in the transfer aisle, which is not applicable to Ares Upperstage.
Not quite. The USS segments were processed and stacked in HB4, not the xfer aisle. If they were, they would have been in the way for Shuttle ops. Remember, the orbiter takes up a significant chunk of the xfer aisle. The ETs are no different.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline Hungry4info3

  • Full Member
  • ****
  • Posts: 448
  • Liked: 27
  • Likes Given: 19
Re: Ares I-X Q&A
« Reply #37 on: 10/22/2009 02:48 AM »
Will the Ares I-X be throttled down for Max-Q? Searched around but didn't find it. Or can a SRB even be throttled down?
« Last Edit: 10/22/2009 02:54 AM by Hungry4info3 »

Offline mkirk

  • International Man Of Mystery
  • Full Member
  • ****
  • Posts: 1730
  • Florida/Texas
  • Liked: 32
  • Likes Given: 0
Re: Ares I-X Q&A
« Reply #38 on: 10/22/2009 03:07 AM »
Will the Ares I-X be throttled down for Max-Q? Searched around but didn't find it. Or can a SRB even be throttled down?

SRB thrust is managed by shaping the grain pattern (i.e. at the factory).  Ares I-X is using a shuttle inventory SRM (solid rocket motor) - in fact this will be the oldest shuttle SRM ever fired I believe. Since this is a shuttle booster it will have the same burn pattern as on a shuttle mission and therefore it will have a reduced thrust period that coincides with the shuttle thruttle bucket.  Peak thrust occurs somewhere in the neighborhood of 20 seconds into the flight and then decreases steadily until around 50 seconds where it begins to rise again for a short period (until about 80 seconds) and then steadily decreases until burnout.

Mark Kirkman
« Last Edit: 10/22/2009 03:09 AM by mkirk »
Mark Kirkman

Offline Hungry4info3

  • Full Member
  • ****
  • Posts: 448
  • Liked: 27
  • Likes Given: 19
Re: Ares I-X Q&A
« Reply #39 on: 10/22/2009 03:17 AM »
Thank-you so much!

Tags: