a new vehicle design please give me some advices

[LithiumCassini]

Total:

Mass 32.451 t
Payload 0.472 t 1.041 t (include fairing and controls)
Atom ∆V 7993 m/s
Vacu ∆V 9435 m/s

First stage:

Propel mass 22.838 t

(ratio)
LH2 46055.2
LO2 17155.3

Tank mass 1.662 t

Total mass 26.816 t

Engine mass 0.143*7 (1.001) t
Thrust 54.813*7 (383.691) KN
Isp 316~373s

Second stage:

Propel mass 4.148 t

(ratio)
LH2 8366.1
LO2 3116.3

Tank mass 0.302 t

Total mass 5.635 t

Engine mass 0.143 t
Thrust 54.813 KN
Isp 316~373s

 

[PhantomCruiser]

What kind of help?

 

[LithiumCassini]

ah, about the optimization in staging and TWR

I intend to use this vehicle to start up a new company, because of lacking partners and I can't design everything...so please...
about TWR, should I increase or decrease the thrust? I'm using the same engines for upper stage and first stage (eh, the nozzle is different). one for 2nd stage and 7 for the 1st stage
about staging, should I increase the ∆V of which stage or not? do I need a third stage or boosters?
thanks a lot!

 

[PhantomCruiser]

You should be able to plug those numbers into a scenario using multistage. Hang on.

This is a butchered up .ini file from the sample.

[MISC]
cog=25

[TEXTURE_LIST]
TEX_1=Exhaust_atsme

[STAGE_1]
MeshName="multistage\stage2"
IGNITE_DELAY=10.
Diameter=8.0
Height=32.54
EmptyMass=3978
FuelMass=22838
Thrust=383691
BurnTime=600
off=(0.,0.,37.5)
eng_1=(-1.5,0,-16.5)
ENG_PSTREAM1=contrail

[SEPARATION_23]
MeshName="multistage\sep23"
SEPARATION_DELAY=2.0
Diameter=8.0 
Height=5.0
EmptyMass=1.0 
off=(0.,0.,55.715)

[STAGE_2]
MeshName="multistage\stage3"
IGNITE_DELAY=2.
Diameter=5.0 
Height=11.95
EmptyMass=1497 
FuelMass=4148
Thrust=54813
BurnTime=300
off=(0.,0.,62.215)
eng_1=(0,0,-6)
eng_diameter=2
ENG_TEX=Exhaust_atsme

[FAIRING]
N=2
MeshName="multistage\fairing"
Diameter=5.0
Height=16.53
angle=0.
off=(1.25,0.,76.48)

[PAYLOAD_1]
off=(0.,0.,74.5)
speed=(1.,0.,1.)
rot_speed=(0.,0.,0.5)
MeshName="multistage\maqsat1"
Module="multistage\maqsat"
name="maqsat-1"
Diameter=4.8
Height=4.
Mass=650

Here's a scenario

BEGIN_DESC
Launch 3 stage rocket from Kennedy Space Center.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51982.9067479746
END_ENVIRONMENT

BEGIN_FOCUS
  Ship Test
END_FOCUS

BEGIN_CAMERA
  TARGET Test
  MODE Extern
  POS 2.89 0.74 -110.96
  TRACKMODE TargetRelative
  FOV 70.00
END_CAMERA

BEGIN_STATIONS
END_STATIONS

BEGIN_SHIPS
Test:Multistage\Multistage2
DEMO_2:Multistage\Multistage2
  STATUS Landed Earth
  BASE Cape Canaveral:4
  HEADING 0.00
  FUEL 1.000
  CONFIG_FILE Config\multistage\test.ini
  CONFIGURATION 0
  CURRENT_BOOSTER 1
  CURRENT_STAGE 1
  CURRENT_PAYLOAD 1
  FAIRING 1
END
END_SHIPS

This is from the generic multistage sample, so forget about what it looks like it's just boilerplate. I just tossed some numbers in there for the engine burn times, but it looks as if you'll need some boosters. I started falling back down into the atmosphere before I got to 20Km in altitude, and I was not getting very much speed.

 

[LithiumCassini]

thank you, but which one do you think is better, orbiter or KSP+RO+RF+FAR+RSS?

 

[PhantomCruiser]

Orbiter is my preference. There were some KSP forum users (probably a bunch of kids) that turned me off of Kerbal. There are plenty of people here that use KSP regularly, if you are on the forum there might recognize some names.

Can you tell me what the burntime of the engines are? For both stages? It will help me get a clearer picture of how the rocket performs.

 

[Urwumpe]

thank you, but which one do you think is better, orbiter or KSP+RO+RF+FAR+RSS?

The key question should be: Better for what? What is your goal?

KSP is a lot more gamified than Orbiter, which makes it way more accessible, especially for younger persons, but it also avoids to be overly realistic. You will always work with a rather simplified engine and a LEGO brick like model to easily construct your rockets.

In Orbiter, you are free to write your own simulation modules in C++ to the extent of looking closely at the nuts and bolts. You can include factors that are hard to represent in KSP. You can enjoy a gravitation model and mathematical fidelity, that KSP does not even intent to have and which all those add-on modules you cite not even care for.

But looking at your numbers, you are at the low end of the launcher masses, which means that traditionally less important factors will have a strong effect on your launcher. For example, thrust structure, electric conduits, piping, ullage space, pressurization. At low masses, even the interfaces to the ground support equipment will matter.

And much more critical: You have done a large blunder with the mixture ratio for the engines. The single Oxygen atom weights more than the two Hydrogen atoms that react with it. LH2 needs more volume, but weights less than the smaller LO2 tank.

---------- Post added at 11:52 AM ---------- Previous post was at 11:44 AM ----------

Can you tell me what the burntime of the engines are? For both stages? It will help me get a clearer picture of how the rocket performs.

Quick calculation: 217s for the first stage. 276s for the second stage.

 

[PhantomCruiser]

Given those numbers? This is just an easily intercepted tactical ballistic missile. Going to need a lot more thrust from the first stage and maybe some boosters. The second stage might be OK, but have to get it up there first.

 

[Urwumpe]

Given those numbers? This is just an easily intercepted tactical ballistic missile. Going to need a lot more thrust from the first stage and maybe some boosters. The second stage might be OK, but have to get it up there first.

Well, 12.5 m/s² initial acceleration isn't too slow, this goes up to 5 g for the first stage and 6.5 g for the second stage. The DV numbers are sound, but use some optimistic structural values.

But then: Fairing and control mass are a bit mixed up to payload.

 

[Linguofreak]

The key question should be: Better for what? What is your goal?

Well... From his first response to Cruiser, I'd say that he's looking to design a real-life launch vehicle.

I intend to use this vehicle to start up a new company, because of lacking partners and I can't design everything...

 

[Urwumpe]

Well... From his first response to Cruiser, I'd say that he's looking to design a real-life launch vehicle.

Then he is possibly wrong using a KSP design as template.

---------- Post added at 03:19 PM ---------- Previous post was at 03:15 PM ----------

I intend to use this vehicle to start up a new company, because of lacking partners and I can't design everything...so please...

Just as reminder: Starting a new company and getting a new launch vehicle on the launch pad are two separate large challenges. The rocket is the smaller one. A launch vehicle consists of WAY more components than just the vehicle that flies into space.

 

[PhantomCruiser]

Do my numbers here look right? I only managed to make an IRBM with these. :shrug: Of course it's late for me, there may be something obvious I've overlooked.

[MISC]
cog=25

[TEXTURE_LIST]
TEX_1=Exhaust_atsme

[STAGE_1]
MeshName="multistage\stage2"
IGNITE_DELAY=10.
Diameter=8.0
Height=32.54
EmptyMass=3978
FuelMass=22838
Thrust=383691
BurnTime=217
off=(0.,0.,37.5)
eng_1=(-1.5,0,-16.5)
ENG_PSTREAM1=contrail

[SEPARATION_23]
MeshName="multistage\sep23"
SEPARATION_DELAY=2.0
Diameter=8.0 
Height=5.0
EmptyMass=1.0 
off=(0.,0.,55.715)

[STAGE_2]
MeshName="multistage\stage3"
IGNITE_DELAY=2.
Diameter=5.0 
Height=11.95
EmptyMass=1497 
FuelMass=4148
Thrust=54813
BurnTime=276
off=(0.,0.,62.215)
eng_1=(0,0,-6)
eng_diameter=2
ENG_TEX=Exhaust_atsme

[FAIRING]
N=2
MeshName="multistage\fairing"
Diameter=5.0
Height=16.53
angle=0.
off=(1.25,0.,76.48)

[PAYLOAD_1]
off=(0.,0.,74.5)
speed=(1.,0.,1.)
rot_speed=(0.,0.,0.5)
MeshName="multistage\maqsat1"
Module="multistage\maqsat"
name="maqsat-1"
Diameter=4.8
Height=4.
Mass=650

 

[Urwumpe]

Your empty mass of the first stage is about 1000 kg to high.

 

[PhantomCruiser]

"Engine mass 0.143*7 (1.001) t"

Didn't catch that. I figure it should have been part of the total mass?
I'll fix it and try again.