Author Topic: 1 1/2 SD CLV  (Read 26754 times)

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
1 1/2 SD CLV
« on: 03/08/2007 02:21 PM »
Hello !

If you push the "Shuttle-Derived  Crew Launch Vehicle" concept to the limit, and stay close to the original ESAS line/intent, you might get to evaluate this asymmetrical "paper rocket" :

1 x 4 segment SRB, attached at intertank and aft, recoverable
1 x SSME (or derived), ground start, in-line, expendable
tankage smaller than Shuttle's, but same technology; expendable
MECO like Shuttle; tank separation and reentry like Shuttle
CEV per current baseline; orbits, missions per ESAS

I'm trying to figure out some numbers - any input from the forum members shall be greatly appreciated ! All I can offer now is:
GLOW ~ 2 mil. lbm;
thrust at lift-off ~ 3.7 mil. lbf.

Please enjoy : heil or boo at the following claims:

+ tried technology, low development cost
+ ground start SSME (derived)
+ acceptable hight; no issues with VAB, LUT, crawler
+ no roll controll issues
+ no pitch moment nulling issues
+ no capability issues (mass to orbit)
+ all avionics in CEV (except for SSME controller)
- side mount, diminished efficiency
- side mount, increased risk for LOM
- single engine; no engine-out capability

Graphic elements borrowed without permission from the famous : DIRECT_Launcher_Release_v1.1.2.pdf

Offline bad_astra

  • Full Member
  • ****
  • Posts: 1872
  • Liked: 254
  • Likes Given: 311
Re: 1 1/2 SD CLV
« Reply #1 on: 03/08/2007 02:24 PM »
Wouldn't fly.
"Contact Light" -Buzz Aldrin

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #2 on: 03/08/2007 02:38 PM »
Disposal SSME is not cost effective and also the production line is shut down
there are major or impossible roll and control issues to over come
the current fwd SRB attach point is based having a another one to react to.

concept is non viable


Offline mong'

  • Whatever gets us to Mars
  • Full Member
  • ****
  • Posts: 689
  • Liked: 0
  • Likes Given: 0
Re: 1 1/2 SD CLV
« Reply #3 on: 03/08/2007 02:44 PM »
also there is still the challenger failure mode

Offline charlieb

  • Veteran
  • Full Member
  • ****
  • Posts: 617
  • King of Prussia, PA, USA
  • Liked: 0
  • Likes Given: 6
RE: 1 1/2 SD CLV
« Reply #4 on: 03/08/2007 03:20 PM »
Look up in the dictionary  "asymetric thrust" - you'd find this as the illustration.  Man-o-man you wanna blab about attitude control issues - woah babe.  If the SSME quit running with the SRB still attached - it'd be instant cartwheel in the sky for starters - especially at the higher altitudes.  It'd be real ugly..
Former Shuttle Mission Ops Eng  (In them days DF24 - INCO GROUP/COMMS, Now DS231-AVIONICS BRANCH).

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #5 on: 03/08/2007 04:34 PM »
Quote
mong' - 8/3/2007  10:44 AM

also there is still the challenger failure mode

That is not a failure "mode" nor is there a requirement to eliminate it.  See Ares V

Offline mong'

  • Whatever gets us to Mars
  • Full Member
  • ****
  • Posts: 689
  • Liked: 0
  • Likes Given: 0
Re: 1 1/2 SD CLV
« Reply #6 on: 03/08/2007 08:52 PM »
Ares V will be manrated but won't carry crews, at least not in the lunar and mars architectures developped in ESAS so there is a will to eliminate this risk

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #7 on: 03/09/2007 12:57 AM »
Quote
mong' - 8/3/2007  4:52 PM

Ares V will be manrated but won't carry crews, at least not in the lunar and mars architectures developped in ESAS so there is a will to eliminate this risk

Who says it won't carry crews (Ares IV).  Why spend the $ to manrate if it isn't going to be used for it.  Anyways it has solids next to a tank.  There is no documented NASA requirement or "desirement" to elminate this.

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #8 on: 03/13/2007 10:26 AM »
Quote
bad_astra - 8/3/2007  5:24 PM

Wouldn't fly.

Thank you !
Axially asymmetric launch vehicles have flown before and are currently flying. The Shuttle is an example.

Offline kevin-rf

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8652
  • Overlooking the path Mary's little Lamb took..
  • Liked: 1124
  • Likes Given: 243
Re: 1 1/2 SD CLV
« Reply #9 on: 03/13/2007 11:31 AM »
So is the single solid Atlas V variant, 411/511(?).
If you're happy and you know it,
It's your med's!

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #10 on: 03/13/2007 11:38 AM »
Quote
Jim - 8/3/2007  5:38 PM

Disposal SSME is not cost effective and also the production line is shut down
ESAS was eager to use them and then the air-start issue proved to be not practical.
But what about the cheaper, disposable, ground-started SSME ?
Boosted SSTO schemes with high vac Isp motors - like the Shuttle - work like magic - technically.
What has to be cost effective is the launch vehicle in toto. If you can talk about "cost effectiveness" at all wrt CLV.

Quote
there are major or impossible roll and control issues to over come
Major issues- yes, until they're solved. After that they become "brilliant engineering".

Quote
the current fwd SRB attach point is based having a another one to react to.
I agree, new tank structure. Like for every new launch vehicle ever developed.

Quote
concept is non viable
Jim, you might be right.
Or, some serious entity - COTS contender, space faring entrepreneur - might some day say: SDLV is an option !

renclod


Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #11 on: 03/13/2007 11:53 AM »
Quote
renclod - 13/3/2007  8:26 AM

Quote
bad_astra - 8/3/2007  5:24 PM

Wouldn't fly.

Thank you !
Axially asymmetric launch vehicles have flown before and are currently flying. The Shuttle is an example.

Not this severe.

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #12 on: 03/13/2007 12:09 PM »
Quote
kevin-rf - 13/3/2007  3:31 PM

So is the single solid Atlas V variant, 411/511(?).

Right :

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
RE: 1 1/2 SD CLV
« Reply #13 on: 03/13/2007 01:00 PM »
Quote
charlieb - 8/3/2007  6:20 PM

Look up in the dictionary  "asymetric thrust" - you'd find this as the illustration.  Man-o-man you wanna blab about attitude control issues - woah babe.  If the SSME quit running with the SRB still attached - it'd be instant cartwheel in the sky for starters - especially at the higher altitudes.  It'd be real ugly..
-----
former shuttle flight controller (JSC-DF24), current sat ops engineer

Exactly, I "wanna blab about attitude control issues" - I find this topic most interesting.

What do you mean, charlieb : was this type of guidance studied and found impossible ?
No mitigation for this failure mode ? SRM gimbal angle of ~7 deg not wide enough ?
Or SRM gimbal rate of ? deg/sec not fast enough ?
Of course, with a single motor quitting, you have LOM but you're saying also LOC ? No time for the LAS to fire ?

I'm currently reading my way through papers available online (for free  :cool: ), like from Georgia Tech, but it's a paine...

For example :
http://etd.gatech.edu/theses/available/etd-01032005-164555/unrestricted/dukeman_greg_a_200505_phd.pdf
http://controls.ae.gatech.edu/papers/calise_gnc_03.pdf
But I've found very little about axially asymmetrical LV.

Go ahead, charlieb, please, show me where else shall I look. Thank you !

renclod


  • Guest
Re: 1 1/2 SD CLV
« Reply #14 on: 03/15/2007 03:00 AM »
Very original and interesting, renclod. Reminds me of "bimese" and "trimese" concepts, and some discussion of thrust vectoring that was beyond me years back

Assume for the moment you could dynamically stabilize this vehicle with flight software, would such loads compromise the structural integrity of the hardware as it currently exists? Would staging such a vehicle present problems, or just be like Shuttle?

Offline aftercolumbia

  • Member
  • Full Member
  • **
  • Posts: 265
  • Liked: 0
  • Likes Given: 0
Re: 1 1/2 SD CLV
« Reply #15 on: 03/15/2007 04:23 PM »
I'm going to hit the "asymmetric" thrust issue with the proper technicalese:

Based on the first impression, it would appear that the angle of attack (alpha) is approximately 8 degrees from lift-off through max-q and then increases to about 13 degrees near staging (I actually got my protractor out.)  The Shuttle is about 2deg from lift-off through max-q and goes up only slightly during ascent, the virtue of the boosters flanking the tanks, and there being two of them.  The Atlas V 411/511 configurations would have similar alphas by virtue of the SRBs being very much smaller.  Remember also that Atlas V uses a propellant combination of approximately 1.02 average density, whereas the fluffy External tank hs 0.31 and more unused stage volume.  Therefore the Atlas V 411/511 core has more control over the center of gravity position, and therefore the thrust axis and alpha.

The loads situation created by such high alphas would be huge problems for this vehicle.  The SRB thrust loads want to enter the vehicle at a strange aft position creating an ugly bending moment and ruining the intertank arrangement of the original (may force loadbearing structures into the LH2 tank.  This problem is the "common bulkhead killer" for the SSME stage of the Shuttle Derived Vehicles (Doug Stanley brought this up when he mulched Direct.)  The high alpha leads to two massive problems:

1. The vehicle will have lots of drag during max-q.  This is more of a structural issue than a performance one.  It is likely that shifting positions of boundary transition/separation points will wreak havoc with predicting drag loads and moments, in turn wreaking havoc on the control system design and guidance software.  This will lead to higher booster performance dispersions, and therefore higher performance reserve residuals, making the booster less efficient.

2.  The booster will move sideways at lift-off and have to turn to align the thrust axis to the vertical.  This creates a very delicate ground proximity situation.  It is unlikely that the SRB plume will align with its flame trench until tower clearance for example.  There has to be a considerable clearway on the "core side", which is clear of umbilical towers and other things that can be damaged by the plumes or collided into by the booster.  The situation for this booster isn't as nasty as the one I created for myself in Mars Challenger.  The squat Judith booster was originally supposed to be able to take off with four of its five motors.  When an outboard motor was out, all this stuff came into play, including rediculous gimbal angles and the notion of the Judith lander cutting itself apart to make a lane for the booster's lift-off translation.  I gave up pretty fast on that idea once I started seriously looking at these problems.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #16 on: 03/15/2007 09:27 PM »
The structual attachments are the problem for the concept

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #17 on: 03/20/2007 02:56 PM »
Quote
nobodyofconsequence - 15/3/2007  7:00 AM

Very original and interesting, renclod. Reminds me of "bimese" and "trimese" concepts, and some discussion of thrust vectoring that was beyond me years back

Thank You ! Great ! The first forum member to show interest is NOBODY OF CONSEQUENCE !!! ;)

Quote
Assume for the moment you could dynamically stabilize this vehicle with flight software, would such loads compromise the structural integrity of the hardware as it currently exists?

The answer is yes, if you think current Shuttle External Tank and current SRB thrust and aft attachments. But I say even half serious contemplation of this asymmetrical CLV concept would agree to a radical redesign. The propellants are roughly 1/3 of the Shuttle's . There's a >23 tone payload on top - the CLV ! The main engine is inline. At a first glance even the SRB-side of the attachments should be different.

Quote
Would staging such a vehicle present problems, or just be like Shuttle?

I'd say no, no problems. At SRB separation (first staging event) the asymmetrical contraption flyes with it's XoZo axes in the orbit plane, SRB on top and SSTO bottom. SRB departs the same general angle like from the Shuttle stack, ~45 deg; same solid rocket motors like current SRB.

Second staging is, of course, the separation of the CLV from it's spent single inline stage.





Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #18 on: 03/20/2007 03:08 PM »
Quote
renclod - 20/3/2007  11:56 AM

I'd say no, no problems. At SRB separation (first staging event) the asymmetrical contraption flyes with it's XoZo axes in the orbit plane, SRB on top and SSTO bottom. SRB departs the same general angle like from the Shuttle stack, ~45 deg; same solid rocket motors like current SRB.


Big problems.  There will be contact during separation

It is undoable.

Lift off is another show stopper.

Offline DMeader

  • Full Member
  • ****
  • Posts: 954
  • Liked: 100
  • Likes Given: 47
Re: 1 1/2 SD CLV
« Reply #19 on: 03/21/2007 06:27 PM »
Quote
Jim - 20/3/2007  12:08 PM

Big problems.  There will be contact during separation

It is undoable.

Lift off is another show stopper.

Be gentle here if I do not use the right terminology or ask silly questions, I admit I'm not a rocket scientist but am trying hard to understand this. Apologies if Aftercolumbia addressed this and I didn't understand.

Assuming 2.8 million pounds thrust at liftoff for the SRB and 400,000 for the single core-stage engine, it seems to me that with the side-mounted SRB providing most of the liftoff thrust, both nozzles would have to be gimballed rather severely to account for the asymmetry and  to allow the vehicle to fly straight. Is there even enough range-of-motion for this to be possible?

What is going to happen at Max-Q? I don't think the liquid engine would be able to throttle back to avoid overstressing the vehicle, or would that not be necessary with this configuration.

I'm really wondering what would happen at separation.  As thrust from the SRB tails off, would not both the core-stage engine and the SRB have to again begin gimbaling rapidly to account for the loss of thrust from the solid, and would not seperation have to occur pretty much at the instant that the decreasing SRB thrust equals the mass of the empty booster? If not and the liquid engine is gimbaling to continue flying straight allowing for the increasing load of the booster as its thrust falls below its own weight, the liquid engine will be pointing in the wrong direction when seperation does occur and I don't know what the vehicle would do at that point.

Again, thank you for your patience!  ;)

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #20 on: 03/22/2007 09:28 AM »
Quote
DMeader - 21/3/2007  10:27 PM

Quote
Jim - 20/3/2007  12:08 PM

Lift off is another show stopper.

Assuming 2.8 million pounds thrust at liftoff for the SRB and 400,000 for the single core-stage engine, it seems to me that with the side-mounted SRB providing most of the liftoff thrust, both nozzles would have to be gimballed rather severely to account for the asymmetry and  to allow the vehicle to fly straight. Is there even enough range-of-motion for this to be possible?


Let me exercise some very simplistic geometry.

Let's say the center of gravity is like in the picture. Is it realistic ?

Fb = 3.3 mil. lbf , booster thrust

Fs = 0.37 mil. lbf, core stage thrust

SRM gimbal angle = 2 deg. (7 deg. max)

core stage motor gimbal angle = 4 deg (10 deg max.)

Then you have null pitch moment.

Side motion, or horizontal translation at liftoff:

Fv = total thrust, vertical axis component = Fb x cos(2deg) + Fs x cos(4deg) = 3.667 mil. lbf. G=1.9 mil.lbf.

Fh = total thrust, horizontal axis component = Fb x sin(2deg) + Fs x sin(4deg) = 0.141 mil. lbf.

The vertical acceleration is 12.53 times the horizontal acceleration.

When you translated the first 300 ft vertically, you also translated ~ 24 ft horizontaly.

Is it so bad ?

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #21 on: 03/22/2007 10:59 AM »
Also the upper attach point is on the wrong spot on the SRB, it has to be in the same place as the shuttle's SRB

Offline kevin-rf

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 8652
  • Overlooking the path Mary's little Lamb took..
  • Liked: 1124
  • Likes Given: 243
Re: 1 1/2 SD CLV
« Reply #22 on: 03/22/2007 12:41 PM »
The lox is much denser (1.140 g/cc) than LH (0.071 g/cc) so your CG for the ET will be far foward of what you drew. And will shift downward with time because of the mass of the Lox/LH engine.

*numbers quickly pulled off of http://www.astronautix.com so they may be wrong.
If you're happy and you know it,
It's your med's!

Offline E_ E_ H

  • Fascinated
  • Full Member
  • ***
  • Posts: 396
  • Southampton, UK
  • Liked: 0
  • Likes Given: 0
Re: 1 1/2 SD CLV
« Reply #23 on: 03/31/2007 12:54 PM »
Is this what happens at NASA? Someone comes up with a radical idea then everyone dismisses it out of hand. IT'S ONLY A CONCEPT! By their very nature these things tend to ask their own technical questions and set challenges, and surely the challenge is to examine them and come up with radical solutions?
Ground control to Major Chris....

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
RE: 1 1/2 SD CLV
« Reply #24 on: 04/11/2007 02:16 PM »
Asymmetrical concepts are not dead yet...

Performance Evaluation of a Side Mounted Shuttle Derived Heavy Lift Launch Vehicle for Lunar Exploration

http://www.ae.gatech.edu/labs/ssdl/Papers/Masters/Thompson%208900%20May%202006.pdf

Next thing I'm gonna find out is that they also studied the asymmetrical CLV... but for some reason they choose not to post in here   ;)


Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #25 on: 04/11/2007 03:07 PM »
ALS and NLS studied many side mounted vehicles.  That is not unusual.   The issue here is side mounting on a single SRB.

Offline meiza

  • Expert
  • Senior Member
  • *****
  • Posts: 3068
  • Where Be Dragons
  • Liked: 3
  • Likes Given: 3
Re: 1 1/2 SD CLV
« Reply #26 on: 04/11/2007 04:28 PM »
Perhaps it'd help if you made the tanks really skinny and tall. (SRB attach at intertank) That way the center of mass would be closer to the thrust axis of the SRB.

Offline bad_astra

  • Full Member
  • ****
  • Posts: 1872
  • Liked: 254
  • Likes Given: 311
RE: 1 1/2 SD CLV
« Reply #27 on: 04/11/2007 06:26 PM »
Quote
renclod - 11/4/2007  9:16 AM

Asymmetrical concepts are not dead yet...

Performance Evaluation of a Side Mounted Shuttle Derived Heavy Lift Launch Vehicle for Lunar Exploration

http://www.ae.gatech.edu/labs/ssdl/Papers/Masters/Thompson%208900%20May%202006.pdf

Next thing I'm gonna find out is that they also studied the asymmetrical CLV... but for some reason they choose not to post in here   ;)


Sidemounting has been going on for awhile. STS comes to mind, as does Buran and Polyus. The main issue with that vehicle is that you will never overcome the initial movement off the pad with the current mlp. Flame trench issues, perhaps even accoustic issues. You could redesign the mounting pounts (and end up with a completely different ET) and try to thrust vector, but at the end of it all why bother. Radical pad changes, tank changes.. cheaper in the end to just go with a sidemounted SDLV (my favorite), or Direct derivative, or a whopping big Longfellow as is the case with Ares V.


It was neat looking, though. Sorry I gave it a two word reply earlier.



"Contact Light" -Buzz Aldrin

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #28 on: 04/17/2007 01:34 PM »
Quote
Jim - 11/4/2007  6:07 PM

ALS and NLS studied many side mounted vehicles.  That is not unusual.   The issue here is side mounting on a single SRB.

Thanks, your post focused my research and I have found a "not unusual", side mounted ALS vehicle study; even if 18 years old, it is my best source yet:

>> Guidance, steering, load relief and control of an asymmetric launch vehicle <<
M.S. Thesis - MIT (- Draper Labs - LaRC - JSC); Author: Boelitz, Frederick W. ; Document ID: 19900004941; source: http://ntrs.nasa.gov ;
PDF : http://hdl.handle.net/2060/19900004941 .

This configuration presents :

"not so severe" thrust asymmetry: 7-to-3 (identical motors, booster-to-corestage) but the C-of-G is "inside" the core stage from lift off all the way to separation.

... constant thrust asymmetry (no throttling) compared to the Shuttle-derived (SD) concept which begins with 3.3-to-0.4 and ends with something like 0.08-to-(0.5 ... 0.3).

... all ten engines installed at 5 deg cant, which I hope the oneSRB/oneSSME asymmetrical concept can do without.

... alphas between 4 and 14 degrees; for the SD concept, aftercolumbia 's guess is 8...13 (what we need here is a jpeg of his protractor at work) , my guess is 2...TBD



Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #29 on: 04/17/2007 02:26 PM »
Quote
kevin-rf - 22/3/2007  4:41 PM

The lox is much denser (1.140 g/cc) than LH (0.071 g/cc) so your CG for the ET will be far foward of what you drew.

My drawing is far from accurate, but I don't think I'm missing wide, the SRB mass is ~1.3 mil.lbm and the core stage is about half that.

Still, if your note is correct, that's good news for steering... you need less severe gimbal angles in order to null the pitch moment.

Quote
kevin-rf
And will shift downward with time because of the mass of the Lox/LH engine.

Also because propellants are staying at the bottom of theire respective tanks :laugh:

The downward shift of the c-of-g with time is one caveat; the shift toward the core stage axys is another.

Quote
meiza - 11/4/2007  7:28 PM

Perhaps it'd help if you made the tanks really skinny and tall. (SRB attach at intertank) That way the center of mass would be closer to the thrust axis of the SRB.


It would help, but there must be some practical limits regarding the proximity of the two motors. Plus structural issues, of course (thicker tank walls).




Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #30 on: 04/17/2007 02:37 PM »
The issue is not just flight design.  The SRB to tank attachment is the big problem.  Strapon sfor most LV apply their loads at the base in the thrust section, where are large structures.  The Shuttle SRB's do it at the foreward attachment.  Since there is only one SRB, the fwd attachment had nothing to react against.  Also you have put the fwd attachment in the middle of the SRM, it needs to be on top.

Offline meiza

  • Expert
  • Senior Member
  • *****
  • Posts: 3068
  • Where Be Dragons
  • Liked: 3
  • Likes Given: 3
Re: 1 1/2 SD CLV
« Reply #31 on: 04/17/2007 08:50 PM »
Had some fun with mspaint, modifying the original proposal.. :)

Offline bad_astra

  • Full Member
  • ****
  • Posts: 1872
  • Liked: 254
  • Likes Given: 311
Re: 1 1/2 SD CLV
« Reply #32 on: 04/17/2007 08:52 PM »
Just place the ET atop the SRB and have Superstick. (*Jim Alert*: This was only in jest)
"Contact Light" -Buzz Aldrin

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #33 on: 04/18/2007 01:08 PM »
Quote
Jim - 17/4/2007  5:37 PM

The issue is not just flight design.  The SRB to tank attachment is the big problem.  Strapons for most LV apply their loads at the base in the thrust section, where are large structures.  The Shuttle SRB's do it at the foreward attachment.  Since there is only one SRB, the fwd attachment had nothing to react against.
I got the point since 8/3

Quote
Jim - the current fwd SRB attach point is based having a another one to react to.
Maybe the SRB forward skirt, redesigned, could take the bending moment.

Quote
Jim - 17/4/2007  5:37 PM
Also you have put the fwd attachment in the middle of the SRM, it needs to be on top.
Just a lazy pixel manipulation of elements borrowed from somewhere else.

Not easy to come up with an accurate representation of the concept. Not until proper simulations are done and the iterations are converging.





Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #34 on: 04/18/2007 01:55 PM »
Quote
renclod - 18/4/2007  9:08 AM

Not easy to come up with an accurate representation of the concept. Not until proper simulations are done and the iterations are converging.


  There is no need for the side struts on the upper attachment, the side struts are in the lower attachment.

The problem is the beam  in the ET

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #35 on: 04/18/2007 05:55 PM »
Quote
Jim - 18/4/2007  4:55 PM

There is no need for the side struts on the upper attachment, the side struts are in the lower attachment.

The problem is the beam  in the ET

The side-stable aspect is not my concern here.


Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #36 on: 04/18/2007 06:03 PM »
Quote
renclod - 18/4/2007  1:55 PM

Quote
Jim - 18/4/2007  4:55 PM

There is no need for the side struts on the upper attachment, the side struts are in the lower attachment.

The problem is the beam  in the ET

The side-stable aspect is not my concern here.


Too overly conplex and not worth the effort.  

1.  The normal SRB fwd skirt must be redesigned
2.  The ET intertank as well

therefore no advantage over inline


-  tried technology, low development cost (not true, major ET and SRB changes)
- ground start SSME (not in production nor is cheaper expendable version possible)
- all avionics in CEV (except for SSME controller)  Why ?  And CEV is not sized for this
- side mount, diminished efficiency
- side mount, increased risk for LOM
- single engine; no engine-out capability
- lift off loads
- angle of attack

Offline MKremer

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 3909
  • Liked: 13
  • Likes Given: 493
Re: 1 1/2 SD CLV
« Reply #37 on: 04/18/2007 06:45 PM »
Quote
renclod - 18/4/2007  12:55 PM
The side-stable aspect is not my concern here.
As with the current SRB mating, the top connection is for the vertical force, the bottom connection is for any lateral forces.

For the tank structure, the single-side SRB vertical force needs to be equally distributed to both the intertank and upper and lower tanks (maybe some type of inter-tank 'force-ring' like the SRBs have in the upper and lower locations, but with an engineered thrust structure within the intertank itself to distribute the offset force equally overall).

The lateral force structure and connections could probably be done the same as with the current SRBs.

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #38 on: 04/19/2007 10:34 AM »
Quote
MKremer - 18/4/2007  9:45 PM

Quote
renclod - 18/4/2007  12:55 PM
The side-stable aspect is not my concern here.
As with the current SRB mating, the top connection is for the vertical force, the bottom connection is for any lateral forces.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980069724_1998134068.pdf
NONLINEAR ANALYSIS OF THE SPACE SHUTTLE SUPERLIGHTWEIGHT LO 2 TANK:
PART I - BEHAVIOR UNDER BOOSTER ASCENT LOADS

Quote
The SRB beam compensates for the eccentricity of
the concentrated loads introduced by the SRBs. The SRB
beam also supports loads that are normal to the intertank
(parallel to the SRB beam) at the SRB attachment points.

Edit:
My initial reply here was wrong, both text and picture. Sorry.


Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #39 on: 04/23/2007 04:06 PM »
Quote
Jim - 18/4/2007  9:03 PM

... no advantage over inline
Not to be antagonistic, but if this parallel-asymmetrical concept is not just a chimera :

Apples-to-apples, parallel versus inline,
hypotetical single SRB and hypotetical single hydrolox engine,
both derived from existing hardware,
unique targeted orbit :

1/ The maximum performance attainable - injected payload mass to the desired LEO - might be better for the parallel configuration (as the hidrolox engine adds impulse from lift off).

2/ The ground start (a la Shuttle) is a clear and huge advantage for the configuration that can feature it.

3/ Operationally, a last moment swap of the hydrolox engine should go faster with a parallel configuration  (is possible without destacking).

4/ The roll control in the first phase of the ascent (when the stack has the largest moment of inertia) might take advantage of having two engines burning in parallel; although the forces are asymmetric, variably asymmetric for that matter, the asymmetry can be modeled.

...in my humble oppinion...



Offline publiusr

  • Elite Veteran
  • Full Member
  • ****
  • Posts: 1540
  • Liked: 1
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #40 on: 04/23/2007 10:19 PM »
Jim's right on this one. At least with Buran, Polus, GTK you had two sets of strap ons and the structure was rigid--with plenty of gimbal.

A single SRB on one side is a nightmare.

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #41 on: 05/07/2007 02:42 PM »
Quote
meiza - 11/4/2007 11:28 AM
Perhaps it'd help if you made the tanks really skinny and tall. (SRB attach at intertank) That way the center of mass would be closer to the thrust axis of the SRB.

bad_astra - 17/4/2007  11:52 PM
Just place the ET atop the SRB and have Superstick. (*Jim Alert*: This was only in jest)

Following both advices to see what gives...
The payload (CEV) and the hidrolox engine (SSME) are missing from the picture.
Oxygen tank: 6m dia, 7.2m height, 164.88 cu.m (0.3 x Shuttle LOX tank volume)
Hidrogen tank: 4m dia, 36.8m height, 451 cu.m (0.3 x Shuttle LH2 tank volume)

* * *

Another interesting study:
http://www.la.dlr.de/ra/sart/publications/pdf/esa01-2001.pdf
REUSABLE HYDRO-CARBON BOOSTER STAGES AS
A REPLACEMENT FOR
LARGE SOLID ROCKET MOTORS
Martin Sippel, Uta Atanassov, Jens Kauffmann, Josef Klevanski, Volker Schmid
Space Launcher Systems Analysis (SART), DLR, Cologne, Germany

Quote
2.1 Single LFBB, single fuselage
At first DLR started an analysis of this most simple
configuration, of which a similar one had already been
regarded within the previous FESTIP study. An updated
design of the vehicles from reference 2 results in
increased system weight and size, which in some cases
with hydrogen-fuel surpassed the length of the core stage
[4].
Such a bizarre configuration can be avoided by using
higher density RP1 as the propellant. One of the
promising configurations in ref. 2 with five NK-33 rocket
engines is redesigned with regard to requirements, and
increased mass margins of the ASTRA-program. This
new analysis also takes fully into account the effects of
necessary engine gimbaling to achieve the static
equilibrium of momentum.



  • Guest
Re: 1 1/2 SD CLV
« Reply #42 on: 05/07/2007 06:30 PM »

Quote
renclod - 23/4/2007  11:06 AM  Not to be antagonistic, but if this parallel-asymmetrical concept is not just a chimera ...
What grates on the nerves of the traditional is that this is unstable to begin with and depends entirely on control theory/application to become stable. Those who believe in real-time flight dynamic controls as being more powerful than presumed vehicle stability by symmetry or center of mass don't have a problem with this.

If you've dealt with symmetric vehicles with engine-out contingencies,  or center of mass contingencies, you deal with asymmetric thrust conditions as an exception. So what you suggest is making it the rule, not the exception, which does not seem like much of a jump for me - believe in software over hardware.

What concerns me more is the booster "walking" on launch out of the flame trench, the torsional/shear between the boosters as the vehicle actively stabilizes itself, the range of the SSME gimbal, slew rates, the thrust level and prestaging propellant consumption cost of "stabilizing", and the development cost of "additions" to kill these new issues.

I prefer attempts to try different things - gets us out of sour old moods and complacency, and stretches the mind.  


Offline savuporo

  • Senior Member
  • *****
  • Posts: 5155
  • Liked: 985
  • Likes Given: 343
Re: 1 1/2 SD CLV
« Reply #43 on: 05/07/2007 08:17 PM »
The flyback booster has actually flown :)
http://www.jf2.com/oldcsaweb/pr010523.html

IIRC these guys had heck of a lot of trouble with CG issues, to get the things to fly.
Orion - the first and only manned not-too-deep-space craft

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #44 on: 05/11/2007 09:42 AM »
Quote
nobodyofconsequence - 7/5/2007  9:30 PM

What grates on the nerves of the traditional is that this is unstable to begin with and depends entirely on control theory/application to become stable. Those who believe in real-time flight dynamic controls as being more powerful than presumed vehicle stability by symmetry or center of mass don't have a problem with this.
I should have started this thread with something like this:

>> Space Shuttle vehicle lift-off dynamics occurring in a transition from a cantilever to a free-free flight phase <<

PEARSON, D. W. (Rockwell International Corp., Space Transportation Systems Group, Downey, CA)
AIAA-1982-1553
In: Guidance and Control Conference, San Diego, CA, August 9-11, 1982, Collection of Technical Papers. (A82-38926 19-18) New York, American Institute of Aeronautics and Astronautics, 1982, p. 304-312.
http://pdf.aiaa.org/preview/1982/PV1982_1553.pdf

... but I just found it, and it's just one page  :frown:

The Shuttle is "the traditional" these days...

The parallel / asymmetrical CLV- featuring the ground started and tested hidrolox engine and a single solid rocket booster - "does not seem like much of a jump for me" either.

I believe the concept deserves a serious study and I really hope such an endeaviour is underway as we "speak" and the abstract will be published.


Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #45 on: 05/11/2007 11:43 AM »
Quote
renclod - 11/5/2007  5:42 AM


I believe the concept deserves a serious study and I really hope such an endeaviour is underway as we "speak" and the abstract will be published.


Nobody is looking at it because is it not worth the effort.  It causes more problems and solves none

Offline publiusr

  • Elite Veteran
  • Full Member
  • ****
  • Posts: 1540
  • Liked: 1
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #46 on: 05/21/2007 11:34 PM »
Agreed.

  • Guest
Re: 1 1/2 SD CLV
« Reply #47 on: 05/22/2007 03:48 AM »

Quote
renclod - 11/5/2007  4:42 AM  I should have started this thread with something like this:  >> Space Shuttle vehicle lift-off dynamics occurring in a transition from a cantilever to a free-free flight phase <<  PEARSON, D. W. (Rockwell International Corp., Space Transportation Systems Group, Downey, CA)  AIAA-1982-1553  In: Guidance and Control Conference, San Diego, CA, August 9-11, 1982, Collection of Technical Papers. (A82-38926 19-18) New York, American Institute of Aeronautics and Astronautics, 1982, p. 304-312. http://pdf.aiaa.org/preview/1982/PV1982_1553.pdf  ... but I just found it, and it's just one page  :frown:   The Shuttle is "the traditional" these days...   The parallel / asymmetrical CLV- featuring the ground started and tested hidrolox engine and a single solid rocket booster - "does not seem like much of a jump for me" either.  I believe the concept deserves a serious study and I really hope such an endeavor is underway as we "speak" and the abstract will be published.  

I agree. I remember the discussions of the asymmetries of the Shuttle (albeit in a plane,  while what you've suggested is much more complex) back in the 70's.  The only reason I opened my mouth about it is I get tired of the "flat earth brigade" - you can make such a vehicle work, but you might not want such a vehicle due to a variety of costs.


Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #48 on: 05/24/2007 12:57 PM »
Quote
Jim - 11/5/2007  2:43 PM
Nobody is looking at it because is it not worth the effort.  It causes more problems and solves none
Then let's try the "cool" factor...

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #49 on: 05/24/2007 01:16 PM »
ugly to me

Offline Martin.cz

  • Member
  • Member
  • Posts: 82
  • Liked: 9
  • Likes Given: 124
Re: 1 1/2 SD CLV
« Reply #50 on: 05/24/2007 02:01 PM »
Cool and crazy :)
btw, another crazy idea:
What abou TWO 4seg SRBS ? :D
Either in side by side:
A
II
or "train config":
A
I
I

  • Guest
Re: 1 1/2 SD CLV
« Reply #51 on: 05/24/2007 09:44 PM »

Quote
renclod - 24/5/2007  7:57 AM  
Quote
Jim - 11/5/2007  2:43 PM Nobody is looking at it because is it not worth the effort.  It causes more problems and solves none
Then let's try the "cool" factor...
Jim's not right here - "Nobody" is looking at it because it *might be worth the effort*. :laugh:

Yes that's cool and definitely non-traditional. Also a little unsettling - reminds me of a two tailed sperm (see http://www.clt.astate.edu/wwilliam/cls_1521_seminal_fluid.htm)


Offline publiusr

  • Elite Veteran
  • Full Member
  • ****
  • Posts: 1540
  • Liked: 1
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #52 on: 06/01/2007 08:48 PM »
Quote
Jim - 24/5/2007  8:16 AM

ugly to me

Agreed.

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #53 on: 07/15/2007 05:07 PM »
Quote
nobodyofconsequence - 25/5/2007  12:44 AM

 reminds me of a two tailed sperm

do they shed one when ready for the real job ?!

Offline AntiKev

  • Veteran
  • Full Member
  • *
  • Posts: 179
  • Pilot
  • Windsor, Ontario
    • James
  • Liked: 0
  • Likes Given: 0
Re: 1 1/2 SD CLV
« Reply #54 on: 07/15/2007 06:20 PM »
Like any other problem in engineering, throw enough people and money at it, and yeah, you can do it.  But sometimes you have to ask why.

Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #55 on: 07/17/2007 11:19 AM »
AntiKev
Quote
- 15/7/2007  9:20 PM
Like any other problem in engineering, throw enough people and money at it, and yeah, you can do it.  But sometimes you have to ask why.
Why ?

Not because they're easy but because they're hard.
To see what else can be done with a single solid rocket booster and a single cryo stage.
To toy with the stage-and-a-half-to-orbit versus the two-stage-to-orbit, parallel/asymmetrical versus in-line, configurations.
To have the liquid fuel engine started before solids ignition.
To keep the liquid fuel engine close to the launch table and free of encapsulation.
To enjoy the freedom to design the tankage to the requirements of the mission without fear of piercing through the roof.
To look at *two* hydrolox engines instead of one, and seek engine-out capability.
To let the Shuttle have her baby quaternions and squatcheloids running allover the place.
Just for the fun of it.
And no, this topic is not about the real world, it's just a paper rocket's struggle to get into the matrix [ Pro/E, APAS(HAPB), POST 3-D et al]

 :)


Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32440
  • Cape Canaveral Spaceport
  • Liked: 11187
  • Likes Given: 331
Re: 1 1/2 SD CLV
« Reply #56 on: 07/17/2007 11:35 AM »
Yes, there are whole bunch of option to play with.  Why not liquid first stage and solid second......

This topic is a waste

Offline bad_astra

  • Full Member
  • ****
  • Posts: 1872
  • Liked: 254
  • Likes Given: 311
Re: 1 1/2 SD CLV
« Reply #57 on: 07/17/2007 02:56 PM »
Quote
This topic is a waste

agreed
"Contact Light" -Buzz Aldrin

  • Guest
Re: 1 1/2 SD CLV
« Reply #58 on: 07/18/2007 03:52 AM »

Quote
AntiKev - 15/7/2007  1:20 PM  Like any other problem in engineering, throw enough people and money at it, and yeah, you can do it.  But sometimes you have to ask why.

Sometimes symmetry costs - like getting a long spindle shaped Stick with incredible roll issues and high stress bulkheads. And more.

Looking at the dynamic stability models of this, it looks a lot better the more one looks at it. It's an oblong top, which you could intentionally rotate and/or reverse successively. Computationally very predictable.

Would the thrust structure joining stages at the top be compromised by asymmetric torques from the two stages, or would the randomization of the acoustical energy from each booster tend to cancel out and thus you'd get self damped structure that might be lighter than that of the Stick?

Don't see it obvious as being more expensive. Only obvious that its different. Uglier things than this make it to a launch pad.


Offline renclod

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1663
  • EU.Ro
  • Liked: 8
  • Likes Given: 2
Re: 1 1/2 SD CLV
« Reply #59 on: 07/19/2007 05:00 PM »
nobodyofconsequence
Quote
- 18/7/2007  6:52 AM
Would the thrust structure joining stages at the top be compromised by asymmetric torques from the two stages, or would the randomization of the acoustical energy from each booster tend to cancel out and thus you'd get self damped structure that might be lighter than that of the Stick
It's obvious to me that your expertise in this area is top, first class. I have little to offer.

The lift-off vibro-acoustics experienced by a stack based on Shuttle SRB(s) are severe. There is a FUNDAMENTAL difference between a symmetrical launcher and one non-symmetrical.
Quote
See http://www.boeing.com/defense-space/space/constellation/references/presentations/Space_Shuttle_Integration_Lessons_Learned.pdf

This is the second time I offer this precious, delicious, informative link.

Page 24 of 84 is my refference here - "Liftoff Loads Analyses".
When a spike in thrust, or jolt, manifests in the SRB(s) (and the ignition is only the first one), an asymmetric launcher's payload (like the Shuttle), given that the SRB thrust axys is NOT going through the centre of mass is taking it (at least partially, depending on the station) like a LATERAL acceleration. This is the well known 2g lateral acceleration (vibration) that the Shuttle crew are submitted to until staging.

On the other hand, a symmetrical launcher will take the same jolt right along it's axys of symmetry, and ALL the pieces composing the stack will experience this shock.




Tags: