Question Velcro Rockets and the rotation of separated boosters

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mikusingularity
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With some launchers made with Velcro Rockets, when the boosters separate, they rotate away from the main stage. With others, they don't rotate at all, and look like they don't separate as quickly.

Is there any way to control the rotation and speed of the booster once it separates from the main rocket?
 
Last edited:
From the manual:

TIPOFF Normally 1. A multiple of the usual rotation rate upon jettison for sideattached
parallel stages. Almost never needed, but I had to set it to 0
for the X-15-Blue Scout scenario to simulate the launching trapeze.

So try TIPOFF 0.0
 
So, if I wanted to get the ground started GEMs of a Delta II to perform their charateristic tumble after sep, that's the line to edit? Sweet. Time for some .cfg and .scn editing.
 
sputnik said:
From the manual:

TIPOFF Normally 1. A multiple of the usual rotation rate upon jettison for sideattached
parallel stages. Almost never needed, but I had to set it to 0
for the X-15-Blue Scout scenario to simulate the launching trapeze.

So try TIPOFF 0.0
Click to expand...
I tried that, and it didn't work.

The launcher in question is the Long March 2F rocket that comes with Donamy's [ame="http://orbithangar.com/searchid.php?ID=5920"]Shenzhou 9 add-on[/ame].

longmarch2f.png

As you can see, the boosters haven't rotated after separation.
 
Hrm... Can you post the .cfg for that in both the stock and modified versions?
 
Actually, it's the Shenzhou9 Launch.scn I tried to modify. Modifications are bolded and colored red and are for shenzboosters 1-4.
Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 56094.4423692677
END_ENVIRONMENT

BEGIN_FOCUS
  Ship shenzcore
END_FOCUS

BEGIN_CAMERA
  TARGET shenzcore
  MODE Extern
  POS 5.41 -123.46 51.49
  TRACKMODE Ground Earth
  GROUNDLOCATION 100.29067 40.95846 9.79
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE Surface
  SPDMODE 1
END_MFD

BEGIN_MFD Right
  TYPE Orbit
  PROJ Ship
  FRAME Ecliptic
  REF Earth
END_MFD

BEGIN_SHIPS
Shenzhou9/Tiangong1:spacecraft\spacecraft3
  STATUS Orbiting Earth
  RPOS -5574698.36 3680769.69 -648677.09
  RVEL 325.761 -850.709 -7654.239
  AROT 98.19 44.01 -116.69
  VROT -0.06 -0.00 0.00
  AFCMODE 7
  PRPLEVEL 0:0.790411
  NAVFREQ 0 0
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 -2 0.178283
  SEQ 1 2 0.999508
  SEQ 2 2 0.149679
  SEQ 3 -2 0.000000
END
Tiantracker:pv34_joint
  STATUS Orbiting Earth
  RPOS -5574698.03 3680769.35 -648677.04
  RVEL 325.761 -850.709 -7654.239
  AROT 27.44 -18.85 -137.24
  VROT 0.00 -0.00 0.06
  ATTACHED 0:0,Shenzhou9/Tiangong1
  AFCMODE 7
  NAVFREQ 0 0
  TRACKING 1
  CURR_ANG 5.737114
  TGT_ANG 5.968515
  ROT_SPEED 2.000000
END
Shenzhou9/TianSA:Spacecraft\Spacecraft3
  STATUS Orbiting Earth
  RPOS -5574698.03 3680769.35 -648677.04
  RVEL 325.761 -850.709 -7654.239
  AROT 59.59 68.04 -149.77
  VROT -0.06 -0.00 -0.00
  ATTACHED 0:0,Tiantracker
  AFCMODE 7
  NAVFREQ 0 0
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 2 0.999365
END
Shenzhou9/ShenzSM:Spacecraft\Spacecraft3
  STATUS Landed Earth
  POS 56.0946091 -20.0093849
  HEADING 225.37
  ATTACHED 1:2,Shenz2nd_stage
  AFCMODE 7
  PRPLEVEL 0:0.859256
  NAVFREQ 94 481
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 -2 0.000000
  SEQ 1 -2 0.000000
  SEQ 2 -2 0.000000
END
Shenztracker:pv34_joint
  STATUS Landed Earth
  POS 56.0946103 -20.0093838
  HEADING 135.37
  ATTACHED 0:1,Shenzhou9/ShenzSM
  AFCMODE 7
  NAVFREQ 0 0
  TRACKING 0
  CURR_ANG 0.000000
  TGT_ANG 0.000000
  ROT_SPEED 4.000000
END
Shenzhou9/ShenzSA:Spacecraft\Spacecraft3
  STATUS Landed Earth
  POS 56.0946103 -20.0093838
  HEADING 225.37
  ATTACHED 0:0,Shenztracker
  AFCMODE 7
  NAVFREQ 0 0
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 -2 0.000000
END
Shenzhou9/ShenzRM:Spacecraft\Spacecraft3
  STATUS Landed Earth
  POS 56.0945942 -20.0093987
  HEADING 225.37
  ATTACHED 0:0,Shenzhou9/ShenzSM
  AFCMODE 7
  PRPLEVEL 0:0.843123
  NAVFREQ 94 481
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 -2 0.000000
  SEQ 1 -2 0.000000
  SEQ 2 -2 0.000000
  SEQ 3 -2 0.000000
END
Shenzhou9/ShenzOM:Spacecraft\Spacecraft3
  STATUS Landed Earth
  POS 56.0945770 -20.0094146
  HEADING 225.37
  ATTACHED 0:0,Shenzhou9/ShenzRM
  AFCMODE 7
  PRPLEVEL 0:0.843123
  NAVFREQ 94 481
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 -2 0.000000
  SEQ 1 -2 0.000000
  SEQ 2 -2 0.000000
END
Shenz2nd_stage:Velcro/shenzhou9/shenz2nd_stage
  STATUS Landed Earth
  POS -80.5280420 28.4587230
  HEADING 360.00
  ATTACHED 2:0,shenzcore
  AFCMODE 7
  PRPLEVEL 0:1.000000
  NAVFREQ 0 0
  CONFIGURATION 0
  PRIMEBOOSTER 1
  CENTERTHRUST 1
  PADBIAS 1.000000
  FAIRING 2 0.10 0.00 -4.00 0.00
  TGT_HEADING 360.000000
  PAYLOAD Fair1 Velcro/Parts/Shenzfairing2 Velcro/Parts/Shenzfairing2 0.00 0.00 9.40 510.00 0.00 1.00
  PAYLOAD Fair2 Velcro/Parts/Shenzfairing1 Velcro/Parts/Shenzfairing1 0.00 0.00 9.40 510.00 0.00 1.00
  PAYATCH Shenzhou9/ShenzSM 0.0 -0.0 -1.75  0.0 0.0 -1.0  -1.0 0.0 0.0
END
shenzcore:Velcro/shenzhou9/shenzcore
  STATUS Landed Earth
  POS 100.2914100 40.9578800
  HEADING 180.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000 2:1.000000 3:1.000000 4:1.000000
  NAVFREQ 0 0
  CONFIGURATION 0
  PRIMEBOOSTER 1
  CENTERTHRUST 1
  ROLLATT 1
  DELAYSTART 8.000000
  PADBIAS 1.000000
  MINPITCH 5.000000
  LES 140.000000
  TGT_HEADING 102.450000
  SERIESBURN 0 shenz2nd_stage 0.0000 0.0000 12.4000 0.0000 0.0000 -1.0000 0.0000 -1.0000 0.0000
  PAYLOAD LES Velcro/Parts/ShenzLES Velcro/Parts/ShenzLES 0.00 0.00 34.35 1020.00 0.00 1.00
END
shenzbooster1:Velcro/shenzhou9/shenzbooster
  STATUS Orbiting Earth
  RPOS -4622781.01 3313217.99 2870966.11
  RVEL -95.427 133.576 -307.808
  AROT 49.09 46.52 156.58
  AFCMODE 7
  NAVFREQ 0 0
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  DELAYSTART 2.00
  [B][color=red]TIPOFF 0.0[/color][/B]
  PADBIAS 1.00
  TGT_HEADING 102.45
  PARALLELBURN 1 shenzcore -0.0500 0.0000 -5.0000 1.0000 0.0000 0.0000 0.0000 0.0000 1.0000
END
shenzbooster2:Velcro/shenzhou9/shenzbooster
  STATUS Orbiting Earth
  RPOS -4622782.42 3313219.97 2870961.55
  RVEL -96.521 135.108 -311.338
  AROT 49.09 46.52 -23.42
  AFCMODE 7
  NAVFREQ 0 0
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  DELAYSTART 2.00
  [B][color=red]TIPOFF 0.0[/color][/B]
  PADBIAS 1.00
  TGT_HEADING 102.45
  PARALLELBURN 1 shenzcore 0.0500 0.0000 -5.0000 -1.0000 0.0000 0.0000 0.0000 0.0000 1.0000
END
shenzbooster3:Velcro/shenzhou9/shenzbooster
  STATUS Orbiting Earth
  RPOS -4622780.02 3313221.03 2870964.19
  RVEL -94.711 135.869 -309.302
  AROT 49.09 46.52 66.58
  AFCMODE 7
  NAVFREQ 0 0
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  DELAYSTART 2.00
  [B][color=red]TIPOFF 0.0[/color][/B]
  PADBIAS 1.00
  TGT_HEADING 102.45
  PARALLELBURN 1 shenzcore 0.0000 0.0500 -5.0000 0.0000 1.0000 0.0000 0.0000 0.0000 1.0000
END
shenzbooster4:Velcro/shenzhou9/shenzbooster
  STATUS Orbiting Earth
  RPOS -4622783.41 3313216.93 2870963.47
  RVEL -97.237 132.815 -309.844
  AROT 49.09 46.52 -113.42
  AFCMODE 7
  NAVFREQ 0 0
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  DELAYSTART 2.00
  [B][color=red]TIPOFF 0.0[/color][/B]
  PADBIAS 1.00
  TGT_HEADING 102.45
  PARALLELBURN 1 shenzcore 0.0000 -0.0500 -5.0000 0.0000 -1.0000 0.0000 0.0000 0.0000 1.0000
END
JSLC_pad:JSLC_pad
  STATUS Landed Earth
  POS 100.2914100 40.9578800
  HEADING 47.37
  AFCMODE 7
  PRPLEVEL 0:1.000000
  EXHAUST 1
  FLOODLIGHTS 1
END
END_SHIPS

BEGIN_ExtMFD
END

If you want the booster .cfg (unmodified):
Code: 
; === Configuration file for vessel class Generic CVEL stage (Shenzbooster) ===

Module = Velcro
Meshname = Velcro/Shenzhou9/ShenzBooster
Size = 12.0

Mass = 3000 ; empty mass [kg]
MaxFuel = 38000 ; max fuel mass [kg]
Isp = 2910.97        ; fuel specific impulse [m/s]
IspSL = 2910.29

MaxMainThrust = 816285
MaxRetroThrust = 0
MaxHoverThrust = 0
MaxAttitudeThrust = 3778
COG_OverGround = 4.0
CameraOffset = 0.0 0.0 18.85
CW = .2 .3 .7 .7
LiftFactor = 0.0
CrossSections = 29 27 3.5
RotResistance = 0.7 0.7 0.3
Touchdownpoints = 0 4.4 -18.98  4.4 0 -18.98  -4.4 0 -18.98

Mayfly = 60.0

; === Attachment specs ===
BEGIN_ATTACHMENT
C  0.0 0.0 13.96     0 0 1  0 1 0  VELCRO1
C  0.000 -2.633 -0.107      0 -1 0  0 0 1  VELCRO2
P  0.0 0.0 13.96     0 0 1  0 1 0  VELCRO3
P  0.000 -2.633 -0.107      0 -1 0  0 0 1  VELCRO4
END_ATTACHMENT

; === Engine reference points ===
ExhaustType =LH2
MEngineVec =0 -0.190643 0.98166
MEngineRef1 = 0 0.276 -7.661
 
:hmm: What's the result if you leave the TIPOFF at 1? Do they rotate at all?
 
MaverickSawyer said:
:hmm: What's the result if you leave the TIPOFF at 1? Do they rotate at all?
Click to expand...
No, not at all.

I'll also throw in the core stage .cfg as well, but I doubt it will hold the key to this issue.

Code: 
; === Configuration file for vessel class Generic CVEL stage (Shenzcore) ===

Module = Velcro
Meshname = Velcro/Shenzhou9/Shenzcore
Size = 18.0

Mass = 9500 ; empty mass [kg]
MaxFuel = 186306 ; max fuel mass [kg]
Isp = 2995.55        ; fuel specific impulse [m/s]
IspSL = 2990.2

MaxMainThrust = 3862000
MaxRetroThrust = 0
MaxHoverThrust = 0
MaxAttitudeThrust = 46778
COG_OverGround = 21.25
CameraOffset = 0.0 0.0 7.5
CW = .2 .3 .7 .7
LiftFactor = 0.0
CrossSections = 79.0 80.0 7.0
RotResistance = 0.7 0.7 0.3
Touchdownpoints = 0 4.4 -21.25  4.4 0 -21.25  -4.4 0 -21.25

; === Attachment specs ===
BEGIN_ATTACHMENT
C  0.0 0.0 29.3      0 0 1  0 1 0  VELCRO1
C  0.0 3.9 0.0      0 0 1  0 -1 0  VELCRO2
P  0.0 0.0 29.3      0 0 1  0 1 0  VELCRO3
P  0.0 3.9 0.0      0 0 1  0 -1 0  VELCRO4
END_ATTACHMENT

; === Engine reference points ===
ExhaustType = LH2
MEngineRef1 = -1.326 -0.001 -12.0
MEngineRef2 = 1.326 -0.001 -12.0
MEngineRef3 = 0.001 1.326 -12.0
MEngineRef4 = 0.001 -1.326 -12.0
 
IDK. The manual is probably the spot to look. I'll dig into it shortly and see what I can find.
 
Please let me know when you find it, because it had me stumped as well.
 
Sorry I misunderstood the question first time; I thought you wanted to prevent rotation, not create some.

Well, at booster separation, Velcro Rockets applies a force for one timestep:

VECTOR3 pos, dir, rot;
GetAttachmentParams (attachpos[1], pos, dir, rot);
AddForce (_V(200*SepForce*GetMass()*rot.x, 200*SepForce*GetMass()*rot.y, 0), _V(0, 0, Tipoff*GetSize()/20));

SepForce is a scalar I set based on experiment, multiplied by the size of the sim timestep.

So, I can think of some ways to break this:
1. Use the Attach Point 0, for lower stages, not 1, for strap-ons (but you haven't done this).
2. Have an absurdly high Irot or RotResistance...but you haven't.

The only oddity I see is that the design intent was that the attachment points for the booster are supposed to be approximately at a physical attach point, and the point described in the scenario file is where that point should attaach to. In each case, the point should be on the outer skin of the cylinder.

But you have attached it at (0.05, 0, -5.0) on the booster. This is so close to zero that it effectively IS zero.

Try moving it to something like (1.5, 0, -5.0) and add the 1.45 to the attach points on the booster:
BEGIN_ATTACHMENT
C 0.0 0.0 13.96 0 0 1 0 1 0 VELCRO1
C 0.000 -1.183 -0.107 0 -1 0 0 0 1 VELCRO2
P 0.0 0.0 13.96 0 0 1 0 1 0 VELCRO3
P 0.000 -1.183 -0.107 0 -1 0 0 0 1 VELCRO4
 
I tried it recently, but it didn't work.
cz2f.png


(I removed the LES from the scenario for this shot because it was supposed to jettison earlier)

edit: I also tried it with the LES, and it didn't work.

*sigh* Anyways, it's okay.
 
Last edited:
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