Scenario Help With Fairings

AlfalfaQc

AlfalfaQc

Future Rocket Engineer
Joined
Jun 19, 2012
Messages
72
Reaction score
0
Points
6
Hello everyone!

I just dowloaded the fantastic Deep Space Communication Satellite and I must say it looks nice. Now, here's my problem: I want to use it on a Velcro Delta IV Heavy with fairings to protect the satellite, but I don't know how to make the fairings release before the satellite. When I press "J", the satellite get released and not the fairings.

I know there is a FAIRING command that makes them separate automatically when a certain pressure is reached, but I don't quite understand how it works (where to put it in the scenario).

Here's my scn file:

Code: 
BEGIN_DESC
The Delta IV Heavy.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 59602.629167
END_ENVIRONMENT

BEGIN_FOCUS
  Ship DeltaCBC
END_FOCUS

BEGIN_CAMERA
  TARGET DeltaCBC
  MODE Extern
  POS 9.73 -0.51 -123.30
  TRACKMODE TargetRelative
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE Surface
END_MFD

BEGIN_MFD Right
  TYPE Orbit
  PROJ Ship
  REF Earth
END_MFD

BEGIN_SHIPS
DSCS:DSCS
  STATUS Landed Earth
  BASE Cape Canaveral:5
  AFCMODE 7
  PRPLEVEL 0:0.250000
  NAVFREQ 0 0
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 0 0
END
DeltaStg2:Velcro/D4Stg2_5m
  STATUS Landed Earth
  BASE Cape Canaveral:6
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  SCREENHEIGHT 250.0
  CAMERA 0 0 20.0
  PAYLOAD Fair1 Velcro/Parts/DeltaIV_5m_heavyfairing_left Velcro/Parts/DeltaIV_5m_heavyfairing_left 0 0 14.25 2043.5 0 0.0 1.0
  PAYLOAD Fair2 Velcro/Parts/DeltaIV_5m_heavyfairing_right Velcro/Parts/DeltaIV_5m_heavyfairing_right 0 0 14.25 2043.5 0 0.0 1.0
  IGNITENEXT 0
  SERIESBURN 0 DSCS 0.0 0.0 0.0 0.0 1.0 0.0

END
DeltaCBC:Velcro/CBC
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  PADBIAS -17.00
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  MaxMainThrust = 1888270.35			; Throttle setting at 57% throughout
  SCREENHEIGHT 225.0
  MINPITCH 10.0
  CAMERA 0 0 50.0
  SERIESBURN 0 DeltaStg2 0.0 0.0 1.2  0.0 1.0 0.0
  PAYLOAD Int Velcro/Parts/Int_CBC_5m Velcro/Parts/Int_CBC_5m 0 0 0 0.1 0 0.0 1.0
  IGNITENEXT 0
END
Dummy1:Velcro/DeltaIVDummyBoost			; Simulates the high-throttle portion from ignition to t+60
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  BOOSTERBURN 1 DeltaCBC 0.75 0.0 0.0 0.0 0.0 -1.0 0.0 
END
Dummy2:Velcro/DeltaIVDummyBoost			; Simulates the throttle-up at T+251 sec.
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  DELAYSTART 251.0
  BOOSTERBURN 1 DeltaCBC 0.01 0.0 0.0 0.0 0.0 -1.0 0.0 
END
LRB1:Velcro/CBC_LRB_L
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  PARALLELBURN 1 DeltaCBC 1.5 0.0 1.0  1.0 0.0 0.0 
END
LRB2:Velcro/CBC_LRB_R
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  PRIMEBOOSTER 0
  CENTERTHRUST 1
  PARALLELBURN 1 DeltaCBC -1.5 0.0 1.0  -1.0 0.0 0.0 
END
LC37:delta4/lpad
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  HEADING 210.00
  AFCMODE 7
  PRPLEVEL 0:1.000000
  THLEVEL 1:1.000000
END
END_SHIPS

Thanks for the help!
 
Velcro Rockets.pdf said:
Fairing 2 0.5 -1.0 0.0 0.0
This line tells the code that there is a fairing, in 2 parts. The 0.5 means that jettison will
happen at 0.5 Pa ambient pressure. The -1.0 0.0 0.0 string tells the code that the first part comes
off with that added velocity vector; subsequent parts get this vector rotated about the Z-axis
clockwise by 360 degrees divided by the number of fairing parts. So fairings with three or more
parts will need to be in a specific order.
The fairing gets jettisoned when the static pressure decreases to the stated value, or when the
stage jettisons. The fairing jettison strips off the requisite number of CVEL payloads; a 3-part
fairing will need the 3 parts defined as CVEL payloads, and the actual payload will have to be
defined later (higher up in the CVEL payload list).
Click to expand...

Where does it go in the .scn? No idea. a pass through a variety of examples found no actual use of the fairing line. Most of the fairings are using the PAYLOAD line on a stage below that of the actual payload. In your case, I would bump it down to the center CBC stage, and adjust the location. That way, when the upper stage activates, the faring will jettison by itself at the same time. In real life, that would actually be a fairly late fairing separation.
 
Yeah, that might work, but I would still like to have the automatic fairing separation
 
I haven't used it much myself, but the Velcro\Launch Vehicles\Conestoga 1620.scn that comes with Velcro Rockets has an example of the use of the FAIRING line.

In your scenario, I think it should go in the DeltaStg2, right before the PAYLOAD lines.

The example scenario uses this:
Code: 
FAIRING 2 1.0 0.0 4.0 0.2

So it's a two part fairing (consistent with your 2 fairing payloads) and it auto-jettisons at 1 pascal static pressure. (~80 km alt)*

I have no idea why the direction of the example scenario has those values. Perhaps you should try -1.0 0.0 0.0 first and then adjust if necessary.


*Here is a table I have made for myself with the static pressure at various altitudes on Earth. Select an altitude that you want the fairing to jettison and use the value of the pressure in the scenario's "FAIRING" line.


ALT (km)|Pressure (Pa)
60​
|
21.956319​
|
61​
|
19.155356​
|
62​
|
16.686657​
|
63​
|
14.513831​
|
64​
|
12.604141​
|
65​
|
10.928158​
|
66​
|
9.459474​
|
67​
|
8.174416​
|
68​
|
7.051774​
|
69​
|
6.072592​
|
70​
|
5.219932​
|
71​
|
4.492472​
|
72​
|
3.832674​
|
73​
|
3.279521​
|
74​
|
2.800236​
|
75​
|
2.387590​
|
76​
|
2.032800​
|
77​
|
1.728172​
|
78​
|
1.466983​
|
79​
|
1.243359​
|
80​
|
1.052175​
|
81​
|
0.888969​
|
82​
|
0.749858​
|
83​
|
0.631467​
|
84​
|
0.530869​
|
85​
|
0.445528​
|

Hope this helps
:cheers:
 
Thanks a lot! That works perfectly! :thumbup:
 
Hi guys, me again :facepalm:

I'm trying to do the same thing with the DeltaIV Medium+(4,2), but the staging is done differently in this. When you look at the stock scenario, the second stage is incorporated inside the first stage:
Code: 
DeltaCBC:Velcro/CBC
  STATUS Landed Earth
  BASE Cape Canaveral:6
  HEADING 270.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  SCREENHEIGHT 225.0
;  PITCHMULTIPLE 0.5
  MINPITCH 20.0
  CAMERA 0 0 50.0
  Fairing 2 2.0 0.0 -2.0 0.0
  PAYLOAD Int Velcro/Parts/Int_CBC_4m Velcro/Parts/Int_CBC_4m 0 0 0 0.1 0 0.0 1.0
  PAYLOAD Int Velcro/Parts/CBC_shield Velcro/Parts/CBC_shield 0 0 0 0.1 0 0.0 1.0
  STAGE Stg2 Velcro/EELV/D4Stg2_4m Velcro/D4Stg2_4m 0 0 22.95 24170.0 0.0 1.0
    PAYLOAD probe probe probe 0 0 29.75 12477.0 0.0 1.0   ; 5300 to GEO Transfer
  ENDSTAGE
  PAYLOAD Fair1 Velcro/Parts/4m_fairing_1 Velcro/Parts/4m_fairing_1 0.99 0 33.8 1043.5 0 0.0 1.0
  PAYLOAD Fair2 Velcro/Parts/4m_fairing_2 Velcro/Parts/4m_fairing_2 -0.99 0 33.8 1043.5 0 0.0 1.0
END

But I would like it to be more like this:

Code: 
DSCS:DSCS
  STATUS Landed Earth
  BASE Cape Canaveral:5
  AFCMODE 7
  PRPLEVEL 0:0.250000
  NAVFREQ 0 0
  RCS 1
  CTRL_SURFACE 1
  CONFIGURATION 1
  CURRENT_PAYLOAD 0
  SEQ 0 0 0
END
DeltaStg2:Velcro/D4Stg2_4m
  STATUS Landed Earth
  BASE Cape Canaveral:6
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  SCREENHEIGHT 250.0
  CAMERA 0 0 20.0
  FAIRING 2 1.0 0.0 4.0 0.2
  PAYLOAD Fair1 Velcro/Parts/4m_fairing_1 Velcro/Parts/4m_fairing_1 0.99 0 33.8 1043.5 0 0.0 1.0
  PAYLOAD Fair2 Velcro/Parts/4m_fairing_2 Velcro/Parts/4m_fairing_2 -0.99 0 33.8 1043.5 0 0.0 1.0
  IGNITENEXT 0
  SERIESBURN 0 DSCS 0.0 0.0 0.0 0.0 1.0 0.0
END

DeltaCBC:Velcro/CBC
  STATUS Landed Earth
  POS -80.5646000 28.5314000
  PADBIAS -17.00
  HEADING 30.00
  TGT_HEADING 095.0
  FUEL 1.000
  CONFIGURATION 0
  MaxMainThrust = 1888270.35
  SCREENHEIGHT 225.0
  MINPITCH 20.0
  CAMERA 0 0 50.0
  PAYLOAD Int Velcro/Parts/Int_CBC_4m Velcro/Parts/Int_CBC_4m 0 0 0 0.1 0 0.0 1.0
  SERIESBURN 0 DeltaStg2 0.0 0.0 1.2  0.0 1.0 0.0
  PAYLOAD Int Velcro/Parts/CBC_shield Velcro/Parts/CBC_shield 0 0 0 0.1 0 0.0 1.0
  IGNITENEXT 0
END

I already added the DSCS vessel in the second file.

But when I start the simulation, it always crashes. I tried to replicate what I did for my DeltaIV Heavy scenario this time with the 4m stage 2 and 4m fairings, but it doesn't work and I don't get why.

Thanks again guys!
 
Remove the empty line between the DeltaStg2 and the DeltaCBC. Orbiter doesn't respond very well to those.
If the problem persists, post the Orbiter.log file and links to the addons needed to replicate the problem.
 
Oh, it worked, thanks. I don't really get why though. I'm not that experienced in coding, but I thought empty lines were simply ignored.
 
You must log in or register to reply here.

Similar threads

Thunder Chicken
Project The Battle for a Flag
Replies
10
Views
5K
Thunder Chicken
Thunder Chicken
Thunder Chicken
Discussion Setting Touchdown Points for Vessels on Solid Planet Surfaces I: The Mass Spring Damper Model
2
Replies
37
Views
13K
Thunder Chicken
Thunder Chicken
Thunder Chicken
Discussion Setting Touchdown Points for Vessels on Solid Planet Surfaces II: Friction Coefficients and Why Vessels Slide Down Hills Even With the Brakes On.
Replies
0
Views
2K
Thunder Chicken
Thunder Chicken
gattispilot
C++ Question Help debugging
2
Replies
31
Views
7K
Buck Rogers
Buck Rogers
Trekkie
Discussion ChatGPT Can help writing Code for Orbiter
5 6 7
Replies
121
Views
32K
nbcfrosty
N
Back
Top