Author Topic: Saturn V modifications needed for maximum discretionary LEO payload?  (Read 15319 times)

Offline joema

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What modifications would have been necessary for a 1970s 3-stage Saturn V to lift the maximum discretionary LEO payload? IOW use a partially-fueled SIVB, trading the TLI propellant mass budget for additional LEO payload.

I assume some SIVB structural reinforcement? Was that ever studied? Can anyone comment on the extent of modifications required?

A few details:

The maximum LEO mass orbited was about 147,363 kg for SA-513 (Skylab), which included about 36,500 kg for the expended SII 2nd stage.

The maximum LEO payload for the Apollo missions was 139,750 kg for Apollo 17 at SIVB 2nd ignition. SIVB dry mass was about 11,400 kg.

The Apollo 17 LEO mass was functional payload, but it wasn't discretionary. IOW the Saturn V couldn't have launched a 128,350 kg satellite (139,750 kg total LEO mass - 11,400 kg SIVB dry mass).  What modifications would have been necessary to life the maximum discretionary LEO payload?

Offline Analyst

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joema - 1/4/2008  4:44 PM

The maximum LEO mass orbited was about 147,363 kg for SA-513 (Skylab), which included about 36,500 kg for the expended SII 2nd stage.

Skylab was ~80,000kg, so 147,363kg is way to high.

Analyst

Offline Jim

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joema - 1/4/2008  10:44 AM

What modifications would have been necessary for a 1970s 3-stage Saturn V to lift the maximum discretionary LEO payload? IOW use a partially-fueled SIVB, trading the TLI propellant mass budget for additional LEO payload.

I assume some SIVB structural reinforcement? Was that ever studied? Can anyone comment on the extent of modifications required?

A few details:

The maximum LEO mass orbited was about 147,363 kg for SA-513 (Skylab), which included about 36,500 kg for the expended SII 2nd stage.

The maximum LEO payload for the Apollo missions was 139,750 kg for Apollo 17 at SIVB 2nd ignition. SIVB dry mass was about 11,400 kg.

The Apollo 17 LEO mass was functional payload, but it wasn't discretionary. IOW the Saturn V couldn't have launched a 128,350 kg satellite (139,750 kg total LEO mass - 11,400 kg SIVB dry mass).  What modifications would have been necessary to life the maximum discretionary LEO payload?

Did the Skylab numbers include the shroud?  Also Skylab went to a 50 degree inclination which is a performance hit.

The IU. a payload adapter and fairing are weights that have to be included.

I have the Saturn v payload planner's guide at home and will look at it




Offline Takalok

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joema - 1/4/2008  10:44 AM
The maximum LEO mass orbited was about 147,363 kg for SA-513 (Skylab), which included about 36,500 kg for the expended SII 2nd stage.

You may be mixing pounds and kilograms.  The Saturn INT-21 was a two stage vehicle with a LEO payload of about 75,000 kg or about 166,000 pounds (thereabouts).  

The original design scheme for Saturn was a modular system that would cease production of the Saturn 1B and provide a variety of "building block" configurations based on the three stages of Saturn V for payloads from the Saturn INT-20 with a LEO payload of 60,500 kg (66 tons) to the 410 foot!!! tall monster SAT-V-24(L) with a payload of 435,000 kg (960,000 pounds!! - 480 tons!!).  

Imagine - 410 feet tall with a 480 ton payload.  Hard to wrap my head around that.

Just as an aside, the larger proposed Saturns used strap-on solid boosters.  The very largest however, used strap on fuel pods with an additional two F-1A engines (total of 7 for the first stage)

Anyway, all these glorious configurations were spelled out in minute detail in the "Final Report - Studies of Improved Saturn V Vehicles and Intermediate Payload Vehicles" done for NASA by MSFC.  

I have it in a PDF which I am attaching (This NASA report has no copyright)
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Offline Archibald

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Part of the designs mentionned above are showed at Astronautix
... that ackward moment when you realize that Jeff Bezos personal fortune is far above NASA annual budget... 115 billion to 18 billion...

Offline joema

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Takalok - 1/4/2008  11:57 AM
...You may be mixing pounds and kilograms.  The Saturn INT-21 was a two stage vehicle with a LEO payload of about 75,000 kg or about 166,000 pounds (thereabouts)....
Thanks for the info and document.

According to the NASA/Marshall SA-513 Flight Evaluation Report, the orbital mass of the Skylab workshop was 88,474 kg. See Table 15-5 "Flight Sequence Mass Summary": http://ntrs.nasa.gov/search.jsp?R=252427&id=4&qs=No%3D90%26Ne%3D41%26N%3D51%2B300%2B4294967039

Likewise the same document lists the total mass injected to LEO on SA-513 as 147,363 kg. I assume that includes SII, orbital workshop, payload shroud (11,630 kg), etc.

My question was what SIVB structural modifications would have been required to use the full three-stage Saturn V LEO payload capability. IOW the standard Saturn V, no F-1A upgrades, just partially fuel the SIVB and use the saved propellant mass budget for useful orbital payload. The scenario would be the standard low-inclination orbit, 170 km altitude.

I assume the standard SIVB couldn't structurally support the additional payload weight, but don't know for sure. Just curious if this was ever studied, or of anyone has opinions on this.

Online nacnud

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Takalok - 1/4/2008  5:57 PM

Imagine - 410 feet tall with a 480 ton payload.  Hard to wrap my head around that.


To put that in perspective that is a one launch ISS! If only...

I asked on another thread but no one answered, was there ever a study for a one F1 engine Saturn 1B?

Offline Jim

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joema - 1/4/2008  3:37 PM

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Takalok - 1/4/2008  11:57 AM
...You may be mixing pounds and kilograms.  The Saturn INT-21 was a two stage vehicle with a LEO payload of about 75,000 kg or about 166,000 pounds (thereabouts)....
Thanks for the info and document.

According to the NASA/Marshall SA-513 Flight Evaluation Report, the orbital mass of the Skylab workshop was 88,474 kg. See Table 15-5 "Flight Sequence Mass Summary": http://ntrs.nasa.gov/search.jsp?R=252427&id=4&qs=No%3D90%26Ne%3D41%26N%3D51%2B300%2B4294967039

Likewise the same document lists the total mass injected to LEO on SA-513 as 147,363 kg. I assume that includes SII, orbital workshop, payload shroud (11,630 kg), etc.

My question was what SIVB structural modifications would have been required to use the full three-stage Saturn V LEO payload capability. IOW the standard Saturn V, no F-1A upgrades, just partially fuel the SIVB and use the saved propellant mass budget for useful orbital payload. The scenario would be the standard low-inclination orbit, 170 km altitude.

I assume the standard SIVB couldn't structurally support the additional payload weight, but don't know for sure. Just curious if this was ever studied, or of anyone has opinions on this.

you are assuming that the 3 stage can lift more than the 2 stage based on what?  One Skylab mission?.  you don't know the performance reserve of the skylab launch

Offline William Barton

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Forgive me for being naive and somewhat innumerate, but I asssume the net payload of the Saturn V to LEO was the Apollo stack (including SLA) plus the TLI fuel and oxydizer. If you put a lead weight on top the the Saturn V equal to the Apollo stack + TLI propellant, and burn the SIVB dry on the way to LEO, wouldn't the net payload be just the same?

Offline Jim

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joema - 1/4/2008  3:37 PM

I assume the standard SIVB couldn't structurally support the additional payload weight, but don't know for sure. Just curious if this was ever studied, or of anyone has opinions on this.

I would say no it couldn't

Offline mike robel

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nacnud - 1/4/2008  3:39 PM
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Takalok - 1/4/2008  5:57 PMImagine - 410 feet tall with a 480 ton payload.  Hard to wrap my head around that.
To put that in perspective that is a one launch ISS! If only...I asked on another thread but no one answered, was there ever a study for a one F1 engine Saturn 1B?
I have never found one.  It almost boggles my imagination that noone ever did it.  I did make a model of one that is probably buried in the NASA model building thread.

Offline Rusty_Barton

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From the November 1, 1958 report

ARMY ORDNANCE SATELLITE PROGRAM
http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=ADA434326&Location=U2&doc=GetTRDoc.pdf

http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA434326

PDF page 174 shows early Saturn I designs, at the time called JUNO V. One with 8 clustered engines and one with a single 1.5-million lb thrust engine. So Von Braun thought about this design in 1958.


Offline joema

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William Barton - 1/4/2008  3:38 PM...If you put a lead weight on top the the Saturn V equal to the Apollo stack + TLI propellant, and burn the SIVB dry on the way to LEO, wouldn't the net payload be just the same?
Yes, but if you off-loaded the TLI portion of SIVB propellant, that would give more payload margin to LEO.

For a non-lunar mission, you could theoretically increase the LEO useful payload to balance the mass of offloaded SIVB propellant. My question was whether SIVB structural modification would have been required (I think yes), and how extensive this would have been.

Offline joema

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Jim - 1/4/2008  3:06 PM...you are assuming that the 3 stage can lift more than the 2 stage based on what?  One Skylab mission?.  you don't know the performance reserve of the skylab launch
That's an excellent point. I was assuming the three-stage version would have more theoretical LEO payload capability, and the performance reserves of the two- and three-stage versions were the same.

However SA-513 (Skylab) actually injected more mass to LEO than the Apollo 17, (147,530 kg vs 140,893 kg; figures updated slightly from my earlier post).

This implies SA-513 carried less performance reserve, or had LEO payload capability similar to the three-stage version, or both. Very interesting.

Offline Rusty_Barton

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In the early 1960's NASA was developing a 1.5-million pound thrust
liquid hydrogen/liquid oxygen engine for "post Saturn vehicles".
The project was canceled in the mid-1960's.

The M-1 rocket engine project - Oct 1, 1963
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730065121_1973065121.pdf


Offline tnphysics

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Did you include the S-II dry mass? The Delta IVH could put more mass in LEO without its upper stage, but most of this would be useless CBC dry mass. You may be seeing this phenomena here.

Offline Jim

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tnphysics - 1/4/2008  8:59 PM

Did you include the S-II dry mass? The Delta IVH could put more mass in LEO without its third stage, but most of this would be useless CBC dry mass. You may be seeing this phenomena here.

The D-IV H doesn't have a 3rd stage.  It is two stage with strapon LRB's.  The core and LRB's can not put a payload in orbit

Offline Jim

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The Saturn v payload planner's guide says 261,000 lbs to 100nmi

Offline Takalok

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Jim - 1/4/2008  9:17 PM

The Saturn v payload planner's guide says 261,000 lbs to 100nmi

This quote is really to the point regarding LEO.  You have to define what LEO is.  The materials I've read from the 60's regarding LEO use 100 nautical miles as the standard (about 115 regular miles).  Also, the orbit you choose obviously affects your payload.

For comparison, the ISS is at about 217 miles, and it is also in LEO.   SkyLab was at about 245 miles.  Also, I belive the ISS is not in as favorable an orbit for NASA as SkyLab was.

That being said, from the previous documentation I posted, and perusing a few other places, it looks like the Saturn's maximum LEO was achived with the INT-21 configuration, consisting of just the first and second stages.  (excluding proposed versions)

Apparently this tread's thoughts that the fuel in the S-IVB would reduce LEO is correct.  However, it seems the best result for LEO is just eliminate the third stage altogether.

Now, if you want enough velocity to reach the moon or mars, you're going to want that extra S-IVB fuel, and few less suitcases.  

 :laugh:  :laugh:
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Offline Jorge

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Takalok - 1/4/2008  8:56 PM

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Jim - 1/4/2008  9:17 PM

The Saturn v payload planner's guide says 261,000 lbs to 100nmi

This quote is really to the point regarding LEO.  You have to define what LEO is.  The materials I've read from the 60's regarding LEO use 100 nautical miles as the standard (about 115 regular miles).  Also, the orbit you choose obviously affects your payload.

For comparison, the ISS is at about 217 miles, and it is also in LEO.   SkyLab was at about 245 miles.  Also, I belive the ISS is not in as favorable an orbit for NASA as SkyLab was.

Skylab's inclination was 50 degrees. ISS, 51.6.

Practically speaking, there is no difference between the two.
JRF

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