Update Multistage2026 - Development thread

[jacquesmomo]

Hi Matias (and Gattispilot )

So here are the results of my tests with 2 groups of Boosters :

• 2 boosters from my Ariane 5 rocket
• 4 boosters from my Ariane 6 rocket

(I've made a 6.6 Ariane 6 rocket.... )

Just a clarification regarding the Ariane 6 4 boosters :
N=1 because there's 1 mesh with all 4 boosters.
When separation => 1 mesh with all 4 boosters (vesselbuilder vessel)
with :
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters)
Then this new vesselbuilder vessel => 4 CHILDS (1 booster each) and the original single mesh (with all 4 boosters) disappears.

For the 2 others boosters from Ariane 5, I use the "stage" system from multistage.

Ok ? Here we go

TEST #1 (1 group with the 4 Ariane6 boosters as single booster)

[BOOSTER_1] ; 4 Boosters P120C from Ariane 6 ===
N=1
meshname=Kourou_Rockets\Ariane6\A6_Booster-14
off=(0,0,5)
height=25.32
diameter=5.16
emptymass=500000
fuelmass=140000
thrust=20000000
burndelay=2
burntime=137
eng_1=(3.799,-3.800,-1.000)
eng_2=(-3.799,3.800,-1.000)
eng_3=(3.799,3.800,-1.000)
eng_4=(-3.799,-3.800,-1.000)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(0,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters

Normal operation


TEST #2 (1 group with the 2 Ariane5 boosters)

[BOOSTER_1] ; 2 Boosters from Ariane 5 rocket ===
N=2
meshname=Kourou_Rockets\Ariane5\A5_Booster
off=(-5,0,25)
height=25.32
diameter=5.16
angle=0
emptymass=500000
fuelmass=140000
thrust=20000000
burndelay=0
burntime=100
eng_1=(0,0,-16)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(-5,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8

Normal operation again


TEST #3
Group 1 with the 2 Ariane5 boosters
Group 2 with the 4 Ariane6 boosters as single booster

[BOOSTER_1] ; 2 Boosters from Ariane 5 rocket ===
N=2
meshname=Kourou_Rockets\Ariane5\A5_Booster
off=(-5,0,25)
height=25.32
diameter=5.16
angle=0
emptymass=10
fuelmass=10
thrust=10
burndelay=0
burntime=100
eng_1=(0,0,-16)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(-5,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8

[BOOSTER_2] ; 4 Boosters P120C from Ariane 6 ===
N=1
meshname=Kourou_Rockets\Ariane6\A6_Booster-14
off=(0,0,5)
height=25.32
diameter=5.16
emptymass=500000
fuelmass=140000
thrust=20000000
burndelay=2
burntime=137
eng_1=(3.799,-3.800,-1.000)
eng_2=(-3.799,3.800,-1.000)
eng_3=(3.799,3.800,-1.000)
eng_4=(-3.799,-3.800,-1.000)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(0,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters

Result:
Group 1: no exhaust and no pstream
Group 2: exhaust and pstream ok


TEST #4
Group 1 with the 4 Ariane6 boosters as single booster
Group 2 with the 2 Ariane5 boosters

[BOOSTER_1] ; 4 Boosters P120C from Ariane 6 ===
N=1
meshname=Kourou_Rockets\Ariane6\A6_Booster-14
off=(0,0,5)
height=25.32
diameter=5.16
emptymass=500000
fuelmass=140000
thrust=20000000
burndelay=2
burntime=137
eng_1=(3.799,-3.800,-1.000)
eng_2=(-3.799,3.800,-1.000)
eng_3=(3.799,3.800,-1.000)
eng_4=(-3.799,-3.800,-1.000)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(0,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters

[BOOSTER_2] ; 2 Boosters from Ariane 5 rocket ===
N=2
meshname=Kourou_Rockets\Ariane5\A5_Booster
off=(-5,0,25)
height=25.32
diameter=5.16
angle=0
emptymass=10
fuelmass=10
thrust=10
burndelay=0
burntime=100
eng_1=(0,0,-16)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(-5,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8

The rocket cannot lift off : the Thrust value of Booster_1 is not taken into account.
(and the Thrust value of Booster_2 is too small)


TEST #5
Group 1 with the 4 Ariane6 boosters as single booster
Group 2 with the 2 Ariane5 boosters
emptymass ; fuelmass ; thrust are modified

[BOOSTER_1] ; 4 Boosters P120C from Ariane 6 ===
N=1
meshname=Kourou_Rockets\Ariane6\A6_Booster-14
off=(0,0,5)
height=25.32
diameter=5.16
emptymass=10
fuelmass=10
thrust=10
burndelay=2
burntime=137
eng_1=(3.799,-3.800,-1.000)
eng_2=(-3.799,3.800,-1.000)
eng_3=(3.799,3.800,-1.000)
eng_4=(-3.799,-3.800,-1.000)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(0,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters

[BOOSTER_2] ; 2 Boosters from Ariane 5 rocket ===
N=2
meshname=Kourou_Rockets\Ariane5\A5_Booster
off=(-5,0,25)
height=25.32
diameter=5.16
angle=0
emptymass=500000
fuelmass=140000
thrust=20000000
burndelay=0
burntime=100
eng_1=(0,0,-16)
eng_diameter=3.5
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
eng_pstream1=booster
speed=(-5,0,0)
rot_speed=(0,0,0)
expbolts_pos=(0,0,20)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8

Result :
The rocket can lift off, BUT still :
Group 1: no exhaust and no pstream
Group 2: exhaust and pstream ok

In conclusion:
The values "emptymass ; fuelmass ; thrust" of [BOOSTER_1] are not taken into account (only [BOOSTER_2] values).
eng_tex and eng_pstream1 of [BOOSTER_1] are not dysplayed (only these of [BOOSTER_2]

 

[Matias Saibene]

Hi Matias (and Gattispilot )

So here are the results of my tests with 2 groups of Boosters :

• 2 boosters from my Ariane 5 rocket
• 4 boosters from my Ariane 6 rocket

(I've made a 6.6 Ariane 6 rocket.... )

Just a clarification regarding the Ariane 6 4 boosters :
N=1 because there's 1 mesh with all 4 boosters.
When separation => 1 mesh with all 4 boosters (vesselbuilder vessel)
with :
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters)
Then this new vesselbuilder vessel => 4 CHILDS (1 booster each) and the original single mesh (with all 4 boosters) disappears.

For the 2 others boosters from Ariane 5, I use the "stage" system from multistage.

Ok ? Here we go

TEST #1 (1 group with the 4 Ariane6 boosters as single booster)



View attachment 48551

Normal operation


TEST #2 (1 group with the 2 Ariane5 boosters)



View attachment 48552

Normal operation again


TEST #3
Group 1 with the 2 Ariane5 boosters
Group 2 with the 4 Ariane6 boosters as single booster



View attachment 48553

Result:
Group 1: no exhaust and no pstream
Group 2: exhaust and pstream ok


TEST #4
Group 1 with the 4 Ariane6 boosters as single booster
Group 2 with the 2 Ariane5 boosters



The rocket cannot lift off : the Thrust value of Booster_1 is not taken into account.
(and the Thrust value of Booster_2 is too small)


TEST #5
Group 1 with the 4 Ariane6 boosters as single booster
Group 2 with the 2 Ariane5 boosters
emptymass ; fuelmass ; thrust are modified



View attachment 48554

Result :
The rocket can lift off, BUT still :
Group 1: no exhaust and no pstream
Group 2: exhaust and pstream ok

In conclusion:
The values "emptymass ; fuelmass ; thrust" of [BOOSTER_1] are not taken into account (only [BOOSTER_2] values).
eng_tex and eng_pstream1 of [BOOSTER_1] are not dysplayed (only these of [BOOSTER_2]

This is very valuable information because I see the problem with the numbering persists.
I'm currently working on Linux to fix a bug in Multistage2026 that prevents the meshes from displaying correctly at launch. I have more diagnostic tools on Linux (Valgrind, for example). So, I'll sync the code with Windows and recompile it.

Once I've recompiled on Windows, I'll look into your case; things are starting to look promising.

I also wanted to let you know that I'm considering porting VesselBuilder to Linux to make even more add-ons available. Initially, I'd remove the configuration UI, and then add ImGui once everything is working.

 

[jacquesmomo]

This is very valuable information because I see the problem with the numbering persists.
I'm currently working on Linux to fix a bug in Multistage2026 that prevents the meshes from displaying correctly at launch. I have more diagnostic tools on Linux (Valgrind, for example). So, I'll sync the code with Windows and recompile it.

Once I've recompiled on Windows, I'll look into your case; things are starting to look promising.

I also wanted to let you know that I'm considering porting VesselBuilder to Linux to make even more add-ons available. Initially, I'd remove the configuration UI, and then add ImGui once everything is working.

So I trust in you, and again, take your time.

Regarding Vesselbuilder, you're brave, because you're taking on a big project.
And here too, if you need a tester, I think I know this module well.
I've found a few (minor) bugs; I can tell you about them when the time comes.
I've made for myself a "doc" (I forget tips quickly) if you're interested, but it's in French.

One last thing : I'm still on Windows 7... dinosaur but that doesn't seem to be a compatibility issue.

 

[jacquesmomo]

Hi Matias

Another small thing I noticed (again, nothing serious, minor)

Just a reminder about my section [Stage_1]

[STAGE_1] ;=== Etage n°1 (LLPM H150) ou Principal (2/2) ===
meshname="Kourou_Rockets\Ariane6\A6_262_stage1"
off=(0,0,23)
height=38.500
diameter=5.560
emptymass=20000
fuelmass=45000
thrust=1500000
ignite_delay=0.001
burnTime=321
pitchthrust=50000
yawthrust=50000
rollthrust=20000
eng_1=(0,0,-20.0)
eng_diameter=3
eng_tex=Kourou_Rockets\Exaust\Exaustmomo_03
speed=(0,0,-3.5)
rot_speed=(0,0,0)
expbolts_pos=(0,0,40)
expbolts_pstream=Expbolts
expbolts_anticipation=0.8
module=..\Kourou_Rockets\Ariane6\A6_Stage1
name=Stage1

After the separation, the stage_1 should take the name "Stage1"
but it takes the one defined with the "module" command/line



I don't remember if it did same with the multistage module for Orbiter 2016... I'll check...

Have a good day.

 

[Matias Saibene]

Hi Matias

Another small thing I noticed (again, nothing serious, minor)

Just a reminder about my section [Stage_1]



After the separation, the stage_1 should take the name "Stage1"
but it takes the one defined with the "module" command/line

View attachment 48562

I don't remember if it did same with the multistage module for Orbiter 2016... I'll check...

Have a good day.

Well, I think the parser I tried to fix ended up doing black magic.

 

[Matias Saibene]

Hi Matias

Another small thing I noticed (again, nothing serious, minor)

Just a reminder about my section [Stage_1]



After the separation, the stage_1 should take the name "Stage1"
but it takes the one defined with the "module" command/line

View attachment 48562

I don't remember if it did same with the multistage module for Orbiter 2016... I'll check...

Have a good day.

After a little investigation, I found the reason for the vessel name: it's using the mesh name.

I'm almost certain the same thing was in Multistage2015; I don't recall adding that feature myself. In fact, I always just adapted the Multistage2015 source code because I'm sure Fred18 did a great job. The only things I added were SimpleINI and some temporary debug logs.
I rewrote some parts from scratch, but always trying to replicate the original functionality.

case TSTAGE:

        GetMeshOffset(stage->at(current).msh_idh, ofs);
        vel = _V(stage->at(current).speed.x, stage->at(current).speed.y, stage->at(current).speed.z);
        Local2Rel(ofs, vs.rpos);
        GlobalRot(vel, rofs);
        vs.rvel.x = rvel.x + rofs.x;
        vs.rvel.y = rvel.y + rofs.y;
        vs.rvel.z = rvel.z + rofs.z;
        vs.vrot.x = vrot.x + stage->at(current).rot_speed.x;
        vs.vrot.y = vrot.y + stage->at(current).rot_speed.y;
        vs.vrot.z = vrot.z + stage->at(current).rot_speed.z;

        mn2 = stage->at(current).meshname;

        oapiCreateVesselEx(mn2.c_str(), stage->at(current).module.c_str(), &vs);

        oapiWriteLogV("%s: Stage n.%i jettisoned name: %s @%.3f", GetName(), current + 1, mn2.c_str(), MET);
        stage_ignition_time = MET;
        break;

 

[Matias Saibene]

Hi Matias (and Gattispilot )

So here are the results of my tests with 2 groups of Boosters :

• 2 boosters from my Ariane 5 rocket
• 4 boosters from my Ariane 6 rocket

(I've made a 6.6 Ariane 6 rocket.... )

Just a clarification regarding the Ariane 6 4 boosters :
N=1 because there's 1 mesh with all 4 boosters.
When separation => 1 mesh with all 4 boosters (vesselbuilder vessel)
with :
module=..\Kourou_Rockets\Ariane6\A6_Boosters64
name=Boosters)
Then this new vesselbuilder vessel => 4 CHILDS (1 booster each) and the original single mesh (with all 4 boosters) disappears.

For the 2 others boosters from Ariane 5, I use the "stage" system from multistage.

Ok ? Here we go

TEST #1 (1 group with the 4 Ariane6 boosters as single booster)



View attachment 48551

Normal operation


TEST #2 (1 group with the 2 Ariane5 boosters)



View attachment 48552

Normal operation again


TEST #3
Group 1 with the 2 Ariane5 boosters
Group 2 with the 4 Ariane6 boosters as single booster



View attachment 48553

Result:
Group 1: no exhaust and no pstream
Group 2: exhaust and pstream ok


TEST #4
Group 1 with the 4 Ariane6 boosters as single booster
Group 2 with the 2 Ariane5 boosters



The rocket cannot lift off : the Thrust value of Booster_1 is not taken into account.
(and the Thrust value of Booster_2 is too small)


TEST #5
Group 1 with the 4 Ariane6 boosters as single booster
Group 2 with the 2 Ariane5 boosters
emptymass ; fuelmass ; thrust are modified



View attachment 48554

Result :
The rocket can lift off, BUT still :
Group 1: no exhaust and no pstream
Group 2: exhaust and pstream ok

In conclusion:
The values "emptymass ; fuelmass ; thrust" of [BOOSTER_1] are not taken into account (only [BOOSTER_2] values).
eng_tex and eng_pstream1 of [BOOSTER_1] are not dysplayed (only these of [BOOSTER_2]

Could you share some Ariane 5 meshes and .cfg files with me (privately if you prefer)?
I may have made a mistake when changing the index of the BOOSTERS parser.

 

[jacquesmomo]

Could you share some Ariane 5 meshes and .cfg files with me (privately if you prefer)?
I may have made a mistake when changing the index of the BOOSTERS parser.

Hi Matias

Sure.
I'll try to make you a zip file with a "secial" 4-boosters configuration
with all the files needed to make it work.

I might not have time tonight, but at the latest tomorrow.

 

[jacquesmomo]

Hi Matias

So I made for you a special rocket with 3 groups of boosters.
I only included the rocket itself (no pad or moving tower) for simplicity.

I'm having trouble setting the ejection of the four A6 boosters.
I haven't been able to adjust "speed=" and "rot_speed="
It's not important, we'll see later

Here is the special "Jacquesmomo" Ariane rocket !!!



So, just to make it easier for you to find (or modify) the files :

• configuration and guidance files (cfg, ini, txt) are in the folder ...\Config\TESTjm
• The msh files are in the folder ...\Meshes\TESTjm are in the folder
• The texture files (rocket elements and exhausts) are in the folder ...\Textures\TESTjm

In the guidance file, I've included a command for just two sounds.
The two sound files are in the folder ...\Config\TESTJm\Sounds

Almost all files are renamed "TESTjm.* ou An_Jm-<element>. (with n=number 4, 5 or 6) except for textures and sounds


You'll find a scn in \Scenarios folder : "TESTjm Multistage 2026"

I hope I haven't forgotten any files...

 

[Matias Saibene]

Hi Matias

So I made for you a special rocket with 3 groups of boosters.
I only included the rocket itself (no pad or moving tower) for simplicity.

I'm having trouble setting the ejection of the four A6 boosters.
I haven't been able to adjust "speed=" and "rot_speed="
It's not important, we'll see later

Here is the special "Jacquesmomo" Ariane rocket !!!

View attachment 48640

So, just to make it easier for you to find (or modify) the files :

• configuration and guidance files (cfg, ini, txt) are in the folder ...\Config\TESTjm
• The msh files are in the folder ...\Meshes\TESTjm are in the folder
• The texture files (rocket elements and exhausts) are in the folder ...\Textures\TESTjm

In the guidance file, I've included a command for just two sounds.
The two sound files are in the folder ...\Config\TESTJm\Sounds

Almost all files are renamed "TESTjm.* ou An_Jm-<element>. (with n=number 4, 5 or 6) except for textures and sounds


You'll find a scn in \Scenarios folder : "TESTjm Multistage 2026"

I hope I haven't forgotten any files...

I'm going to Windows right now to try it out.
Thank you so much for your work!

 

[Matias Saibene]

New Multistage2026 release for testing.

Changes to booster mesh loading. Now detects booster groups.

The error was introduced by me when I migrated the code and wrote new code to use the C++ STL.

 

[jacquesmomo]

New Multistage2026 release for testing.
Changes to booster mesh loading. Now detects booster groups.
The error was introduced by me when I migrated the code and wrote new code to use the C++ STL.

Yes, I'll test now...

Oh, sorry, I forgot one thing :
In the ini file, delete this line in the [FAIRING] section:
module=..\Kourou_Rockets\Ariane6\A6_268_FairingSL
name=Fairing
(you don't have the "module")

 

[jacquesmomo]

Sorry, but... it's not quite right yet...

WITH 3 BOOSTERS GROUPS :
1) Only the last booster displays eng_tex and eng_pstream1

2) During separation before end of combustion (manual with J) => CTD

3) If the rocket launches with the guidance file (P key)

• a) If J is pressed before the end of combustion => CTD
• b) If combustion is finished, none of the 3 groups separate automatically

and pressing J => CTD

WITH 2 BOOSTERS GROUPS : same

WITH 1 BOOSTERS GROUP : ok no issue

 

[gattispilot]

So on my sls. still no booster exhaust.

 

[Matias Saibene]

Sorry, but... it's not quite right yet...

WITH 3 BOOSTERS GROUPS :
1) Only the last booster displays eng_tex and eng_pstream1

2) During separation before end of combustion (manual with J) => CTD

3) If the rocket launches with the guidance file (P key)

• a) If J is pressed before the end of combustion => CTD
• b) If combustion is finished, none of the 3 groups separate automatically

and pressing J => CTD

WITH 2 BOOSTERS GROUPS : same

WITH 1 BOOSTERS GROUP : ok no issue

So on my sls. still no booster exhaust.

That's strange! Did you try it on a clean Orbiter installation?

I can't right now, but later I'll look into what I can do and release a new version, and I'll try it on another clean Orbiter installation.

I think it's a problem with the release, not the code. I must have mixed up some file.

 

[jacquesmomo]

That's strange! Did you try it on a clean Orbiter installation?

For me, no, this isn't a new orbiter installation (clean) , but a special orbiter that I only use to fine-tune my Ariane 6 rocket.
I think we can consider it as "clean" ...

 

[Matias Saibene]

Okay, I've now discovered some typos in the strings that are applied by default when a value in the .ini file is missing, for example, the module.

Please share the Orbiter log for each run/test with me when you can. It would be a great help.

 

[gattispilot]

This is for my SLS

 

[Matias Saibene]

I'm going to try a fresh Orbiter installation. I'll also prepare a testing release on GitHub containing fixed and updated files. This way, we'll have everything in one place for testing and avoid using scattered files.

 

[Matias Saibene]

This is a real puzzle for me, and I don't understand why. I'm testing it on a fresh Orbiter installation, and it turns out that Multistage2026 isn't working correctly when separating stages. I'm getting a CTD error due to out-of-range access.

It worked very well in my previous installation.