Problem Multistage2 rocket exhaust texture problem

[Sky Captain]

I have noticed multistage2 rockets does not show rocket stage exhaust textures correctly.
Exhaust texture is shown as a sphere instead of long flame. It`s strange because when the same rocket with the same parameters is defined as a booster in ini file exhaust texture shows up like it should. Any ideas why such a glitch is occurring?

 

[MJR]

Show me the ini. file for your multistage. Your diameter for the rocket might not be defined even though you think it is. Multistage2 is good, but has bad stuff to it. Show me it and I can tell you what to do. You can also use Exhaust2 for eng_tex.

 

[Sky Captain]

Here is is my ini file although I don`t see any problems with it because I have both rocket and engine diameter defined and when stage 1 from this rocket is defined as a booster for different rocket exhaust texture appears correctly.

[MISC]
cog=2,5
focus=1

[TEXTURE_LIST]
TEX_1=ExhaustLOXKero
TEX_2=ExhaustLOXLH2

[BOOSTER_1]
N=2
MeshName=Multistage\Hercules_I_Fairing
Height=60
Diameter=30
EmptyMass=50000 
angle=180
off=(7.5,0,130.8)
FuelMass=0.00001
Thrust=0.00001
BurnTime=110
Eng_1=(0,0,0)
Eng_Diameter=0.00001
Speed=(10,0,3)
Rot_Speed=(0,-0.1,0)

[STAGE_1]
Height=100
Diameter=20
EmptyMass=1490000
FuelMass=13000000
Thrust=360000000
BurnTime=109
PitchThrust=2250000000
YawThrust=225000000
ROLLTHRUST=225000000
off=(0,-0.15,0)
MeshName="multistage\Hercules_I_Stage1"
eng_1=(0,0,-54)
eng_diameter=20
ENG_TEX=ExhaustLOXKero
SPEED=(0,0,-3)
ROT_SPEED=(0,0,0)

[STAGE_2]
Height=60
Diameter=30
EmptyMass=500000
FuelMass=4000000
Thrust=80000000
BurnTime=220
PitchThrust=125000000
YawThrust=125000000
ROLLTHRUST=125000000
off=(0,0,69)
MeshName="multistage\Hercules_I_Stage2"
eng_1=(0,0,-27)
eng_diameter=20
SPEED=(0,0,3)
ENG_TEX=ExhaustLOXLH2
IGNITE_DELAY=5

[PAYLOAD_1]
off=(0,0,111.8)
speed=(0,0,1)
rot_speed=(0,0,0)
MeshName="LH2TankLight"
Module="spacecraft\Spacecraft3"
name="LH2TankLight"
Diameter=20
Height=75
Mass=950000

 

[MJR]

Try putting the ENG_TEX right after eng_diameter and SPEED last.

 

[Sky Captain]

I tried and nothing changed, exhaust still shows up as a sphere.

 

[MJR]

Its probably the diameter. 20 meters is extremely large beyond standards.

 

[Sky Captain]

Then why this texture glitch affect only rocket`s core stages but not boosters with the same engine parameters?

 

[Sky Captain]

I just put 2 boosters to the rocket and exhaust from boosters shows like it should, but exhaust from core stage shows like a sphere. All engine parameters for boosters and core are exactly the same.

 

[MJR]

On the core stage you said that the diameter was 20 meters. You then defined that the diameter of the exhaust was 20 meters. Try changing it around and see of that helps. Multistage is sensitive so if you have one syntax error even of the minor type it could mess it up and cause this. Keep double checking with the Multistage2 manual and check it because I once had this problem when I was making multistage. If that does not work then I don't know what to tell you.

---------- Post added at 01:39 PM ---------- Previous post was at 01:35 PM ----------

Also, check out this addon. Look at the ini and check how it is setup.

[ame="http://www.orbithangar.com/searchid.php?ID=4103"]Gemini Paraglider (Beta 2)[/ame]

 

[Sky Captain]

I just changed the engine diameter and find out that exhaust on core stage is shown properly only for small engine diameters like 0.5 - 2 m. When I set diameter progressively larger the exhaust texture becomes more and more spherical. It seems that multistage do not scale up exhaust texture properly for core stages.
I also pasted config lines from Gemini Titan rocket ini file into my ini and then set the relevant parameters according to my specifications and nothing changed.

 

[MJR]

Well, at least you have figured out that you can't set ridiculous measurements for eng_diameter.

 

[Sky Captain]

The 20 m figure I get from the article about proposed Sea Dragon rocket which would have used a single 20 m diameter engine with 360 MN of thrust for first stage.

 

[MJR]

Only like you said. Would have used. I doubt engines like that can perform well. They might be powerful, but still.

 

[Sky Captain]

Only like you said. Would have used. I doubt engines like that can perform well. They might be powerful, but still.

Why would it be so? I think it would be preferable for very large rockets to have few large engines than dozens of small ones since it would reduce complexity and chances of failure.

 

[tblaxland]

Why would it be so? I think it would be preferable for very large rockets to have few large engines than dozens of small ones since it would reduce complexity and chances of failure.

Yes but such large engines suffer from flow instabilities in both the combustion chamber and nozzle. Which is why the Russians ended up with the clever design on the R7/Soyuz to use one set of turbo-pumps (the complicated bits) feeding multiple smaller combustion chambers/nozzles (the simple(r) bits).

 

[MJR]

Exactly.

 

[Sky Captain]

Then why did the Sea Dragon designers planned to use a single huge engine if engines so large are not viable because of combustion instabilities? They obviously should have known about this problem. I even remember to read in paper discussing Sea Dragon rocket that combustion instabilities won`t be a problem.

 

[MJR]

Just because they say it is not going to be a problem does not necessarily mean there isn't going to be one. I can guarantee there would have been some at the least.

 

[Sky Captain]

I just read about F1 rocket engine development and in the beginning there were problems with instability, but engineers later managed to solve them.
Anyway for a huge rocket like Sea Dragon intended to be mas produced as cheap as possible it would probably be worth the trouble to solve the instability problem and use one big engine instead of 50 F1 sized engines.

 

[MJR]

You don't need many engines to go to space. It matters about the KN thrust.The Shuttle only has 3 SSMEs and it gets into orbit fine. If a rocket was being mass produced very cheaply I find that dangerous because the more products produced the less quality will matter.