Velcro Saturn B-I + AMSO = Orbit?

[Usonian]

I spent some frustrating hours trying to launch an AMSO CSM into LEO with a Velcro Saturn B-I. I have been weaking the PITCHMULTIPLE and MINPITCH trying to make it work.

Has anyone done this? If so, are you willing to share your scenario file?

I plan to release v2 of Skylab1973 shortly and I want to add crew launch scenario that will allow AMSO fans to fly their preferred CSM.

I will pay BIG for this scenario set up - a credit in my docs, the coin of the Orbiter realm.

 

[sputnik]

You'll have to de-fuel the AMSO; if it's got 1.0 FUELLEVEL, it's loaded for a lunar mission and it's too heavy for a Saturn Ib.

I think.

But I'm not sure what level is historically appropriate. 0.4 or 0.5, I think.

Another gotcha: assuming you're using the attach system (and you will), it doesn't matter where the AMSO vehicle starts the scenario, as it'll snap to where it needs to go. Except, you need to make sure it doesn't start landed on a launch pad, or Orbiter will helpfully load fuel back up to 1.0 for you, which you don't want.
I solved this problem for the C-3 scenario; not sure why I never did did it with a Ib.

 

[Usonian]

Thanks, I will give it a try. Honestly, the fuel load never occured to me. It's also helpful to know why some Velcro launch scenarios start with the attached vessels "STATUS Orbiting Earth"


-----Posted Added-----


Not quite working. I have the AMSO CSM set up in series burn (as it is for the Saturn V) but the autopilot seems to have the whole stack behaving like a three stage rocket, expecting the CSM engine to complete the boost to orbit. Should I set up the CSM as a payload? I recall that the AMSO meshes are scrambled, so the vessel must be fully initiated, and that requires seris burn or payatch. Got any clues?

 

[sputnik]

You should stick with the series burn, and the autopilot doesn't know or care. If it can get you in orbit with two stages, it will. If not, it'll set up for the third stage to try to do the job. Changing the attach method won't have any effect.

Wow. I just tried doing it myself, and I had to cut the fuel all the way down to 18%. Also to fix the SLA masses, which were too high. And I'm not sure 18% fuel is enough to do a Skylab mission. Here's what I used, anyway:

BEGIN_DESC
The Saturn-Ib was an improved Saturn-I.
END_DESC

BEGIN_ENVIRONMENT
System Sol
Date MJD 39307.6367479746
END_ENVIRONMENT

BEGIN_FOCUS
Ship S-Ib
END_FOCUS

BEGIN_CAMERA
TARGET S-Ib
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
AS-506:AMSO\Apollo
STATUS Orbiting Earth
RPOS -4065931.00 591626.06 15607271.12
RVEL -5641.258 120.015 4005.905
AROT -178.28 -50.83 -44.56
RCSMODE 1
PRPLEVEL 0:0.180
NAVFREQ 0 1 2 3
XPDR 0
STATE 8
ABORTSTATUS 0
MISSIONTIME 0.0
PWR 0.000
INVULNERABLE 1
END
S-IVb:Velcro/s4b
STATUS Landed Earth
BASE Cape Canaveral:6
HEADING 0.00
TGT_HEADING 095.0
FUEL 1.000
CONFIGURATION 0
CAMERA 0 0 40.0
SLA 4 -2.0 2.0 0.0
LES 12.0
PAYLOAD Ring Velcro/Parts/S4b_upr_transition Velcro/Parts/S4b_upr_transition 0 0 0.0 0.0 0 0.0

1.0
PAYLOAD SLA1 Velcro/Parts/SLA01 Velcro/Parts/SLA01 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD SLA2 Velcro/Parts/SLA02 Velcro/Parts/SLA02 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD SLA3 Velcro/Parts/SLA03 Velcro/Parts/SLA03 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD SLA4 Velcro/Parts/SLA04 Velcro/Parts/SLA04 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD LES Velcro/Parts/Sat5BPC Velcro/Parts/ApolloLES 0 0.0 28.25 126 0 1
SERIESBURN 0 AS-506 0.0 0.0 -8.2 0.0 1.0 0.0
PAYATCH AS-506_LM_vessel 0.0 -0.0 0.0 0.0 -1.0 0.0 1.0 0.0 0.0
END
S-Ib:Velcro/S-1b
STATUS Landed Earth
BASE Cape Canaveral:6
HEADING 0.00
TGT_HEADING 095.0
FUEL 1.000
CONFIGURATION 0
MINPITCH 20.0
CAMERA 0 0 55.0
SERIESBURN 0 S-IVB 0.0 0.0 -8.9 0.0 1.0 0.0
PAYLOAD Fins Velcro/Parts/S-1bFins Velcro/Parts/S-1bFins 0 0 0 0.0 0 0.0 1.0
PAYLOAD Interstage Velcro/Parts/S4b_to_s4b_interstage Velcro/Parts/S4b_to_s4b_interstage 0 0

-37.5 1000.0 0 0.0 1.0
END
END_SHIPS

 

[Usonian]

Eureka!

I too found the error in the SLA mass. The Scenario file had it at 3500 kg for each of the four sections. According to the Skylab Saturn 1B Flight Manual, NASA, 1972, the total mass for SLA and Ring was 3500 pounds. Divided four ways, the correct mass for each of four SLA is 396.9 kg.

That made all the difference! With a 40% CSM fuel load, I easily reached orbit using the autopilot through all of the first stage and about 1/3 of the second stage burn time. I took over manually from there and even with some clumsy moves had no trouble reaching a 185km x 225km orbit. The Flight Manual indicates an orbit of ~520,000 feet, about 158 km, so I shouldn't have any trouble fiddling around with the autopilot to achive something roughly similar. Getting the correct inclination is the main thing, and the autopilot handles the roll program nicely.

Velcro is one huge addon, so errors are unavoidable. The nice thing about its is the degree of control a user has over all the pieces and the ease with which prblems can be tracked down.

 

[sputnik]

Well, I'm still embarassed.

How are you flying it manually on the second stage that differs from how the autopilot does it? It certainly ought to be possible to get it to do the job hands-off.

 

[Usonian]

I am just now sitting down to tweak the autopilot. My gut feeling is that the autopilot pitches down too fast to 0 degrees immediately after stage 2 ignition, then it pitches back up to 40 degrees (pitch angles from the surface HUD). It seems to work better to slowly pitch down, under manual control, to 0 degrees after staging.

But I will poke around with the autopilot and report back. I am excited about the prospect of opening up Skylab1973 to AMSO users.

As for embarassment, forget about it!


-----Posted Added-----

BEGIN_DESC
The Saturn-Ib was an improved Saturn-I.
END_DESC

BEGIN_ENVIRONMENT

...

S-IVb:Velcro/s4b
STATUS Landed Earth
BASE Cape Canaveral:6
HEADING 0.00
TGT_HEADING 095.0
FUEL 1.000
CONFIGURATION 0
CAMERA 0 0 40.0
SLA 4 -2.0 2.0 0.0
LES 12.0
PAYLOAD Ring Velcro/Parts/S4b_upr_transition Velcro/Parts/S4b_upr_transition 0 0 0.0 0.0 0 0.0 1.0
PAYLOAD SLA1 Velcro/Parts/SLA01 Velcro/Parts/SLA01 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD SLA2 Velcro/Parts/SLA02 Velcro/Parts/SLA02 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD SLA3 Velcro/Parts/SLA03 Velcro/Parts/SLA03 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD SLA4 Velcro/Parts/SLA04 Velcro/Parts/SLA04 0 0 -52.0 500.0 0 0.0 1.0
PAYLOAD LES Velcro/Parts/Sat5BPC Velcro/Parts/ApolloLES 0 0.0 28.25 126 0 1
SERIESBURN 0 AS-506 0.0 0.0 -8.2 0.0 1.0 0.0
PAYATCH AS-506_LM_vessel 0.0 -0.0 0.0 0.0 -1.0 0.0 1.0 0.0 0.0
END

...

END_SHIPS

The red line may be the thing "red lining" your S-1B launch performance

 

[sputnik]

Oops. The dangers of cutting and pasting from another scenario. I'm surprised that even works, since AS-506_LM_Vessel doesn't even exist in this scenario. Thanks!