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The lesser known Saturn IV stage



 
 
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  #1  
Old March 7th 20, 03:24 AM posted to sci.space.history
Greg \(Strider\) Moore
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Default The lesser known Saturn IV stage

https://spaceflightblunders.wordpres...ocket-hotness/
Nope, not the IV-B, but the IV which only flew on the Saturn I.

  #2  
Old March 7th 20, 07:27 AM posted to sci.space.history
David Spain
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Default The lesser known Saturn IV stage

On 2020-03-06 10:24 PM, Greg (Strider) Moore wrote:
https://spaceflightblunders.wordpres...ocket-hotness/

Nope, not the IV-B, but the IV which only flew on the Saturn I.


Which would have made a wicked looking 100MT ICBM. I know, I know,
Saturn was a civilian-only program.

Not exactly silo ready either.... heh.

Since the RL-10 was abandoned in favor of the J2 was there anything of
use in this flight other than testing of the Saturn I first stage?
For example, the avionics package, tankage and pumps, ullage, the helium
purge?

Dave
  #3  
Old March 7th 20, 06:22 PM posted to sci.space.history
Jeff Findley[_6_]
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Posts: 2,307
Default The lesser known Saturn IV stage

In article , says...

On 2020-03-06 10:24 PM, Greg (Strider) Moore wrote:
https://spaceflightblunders.wordpres...ocket-hotness/

Nope, not the IV-B, but the IV which only flew on the Saturn I.


Which would have made a wicked looking 100MT ICBM. I know, I know,
Saturn was a civilian-only program.

Not exactly silo ready either.... heh.

Since the RL-10 was abandoned in favor of the J2 was there anything of
use in this flight other than testing of the Saturn I first stage?
For example, the avionics package, tankage and pumps, ullage, the helium
purge?


This was the first large LH2/LOX upper stage. So I believe that it was
pretty much an engineering pathfinder for the IV-B. It provided
experience with designing, building, and flying a large LH2/LOX upper
stage. I'm sure the lessons learned went into the IV-B.

Jeff
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All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
  #4  
Old March 8th 20, 03:08 PM posted to sci.space.history
David Spain
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Posts: 2,901
Default The lesser known Saturn IV stage

On 2020-03-07 1:22 PM, Jeff Findley wrote:
This was the first large LH2/LOX upper stage. So I believe that it was
pretty much an engineering pathfinder for the IV-B. It provided
experience with designing, building, and flying a large LH2/LOX upper
stage. I'm sure the lessons learned went into the IV-B.


It's hard to have a discussion when we agree on almost every point. ha.

So let's expand the envelop a bit. The J2 used in the Saturn 5 third
stage had to have a restart capability to do LEO and TLI insertions. Was
the ignition system used for that significantly different than that used
for the second stage engines? I suspect not.

I seem to remember the bell housing on the third stage was longer than
that used on the second stage even though same J2 engine. Vacuum
optimization?

Are there ANY applications these days for the new and improved J2X?
I should do a Google search and see. Opinions welcome.

Dave


  #5  
Old March 8th 20, 04:05 PM posted to sci.space.history
Jeff Findley[_6_]
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Posts: 2,307
Default The lesser known Saturn IV stage

In article , says...

On 2020-03-07 1:22 PM, Jeff Findley wrote:
This was the first large LH2/LOX upper stage. So I believe that it was
pretty much an engineering pathfinder for the IV-B. It provided
experience with designing, building, and flying a large LH2/LOX upper
stage. I'm sure the lessons learned went into the IV-B.


It's hard to have a discussion when we agree on almost every point. ha.


True.

So let's expand the envelop a bit. The J2 used in the Saturn 5 third
stage had to have a restart capability to do LEO and TLI insertions. Was
the ignition system used for that significantly different than that used
for the second stage engines? I suspect not.


I'm guessing not as well. Here's a web page detailing the J-2's spark
igniter (the venerable RL-10 also uses a spark igniter).

http://heroicrelics.org/info/j-2/aug...k-igniter.html

One of the (few) advantages of LH2/LOX is that it's relatively easy to
ignite. So you can use a spark igniter to create an engine design that
can ignite as many times as necessary. Unlike kerosene/LOX which often
relies on the chemicals TEA/TEB to insure that ignition takes place
(Merlin does that).

I seem to remember the bell housing on the third stage was longer than
that used on the second stage even though same J2 engine. Vacuum
optimization?


I can't find any evidence of that. This Wikipedia entry lists one
expansion ratio for the J-2 (27.5:1 expansion area ratio).

https://en.wikipedia.org/wiki/Rocketdyne_J-2


Astronautix.com says essentially the same thing:

http://www.astronautix.com/j/j-2.html

The J-2X had a different expansion ratio (80:1), which increased
efficiency compared to the original J-2:

http://www.astronautix.com/j/j-2x.html

Still, if you don't need the higher thrust of the J-2X, the later
versions of the RL-10 are better in almost every way.

Are there ANY applications these days for the new and improved J2X?
I should do a Google search and see. Opinions welcome.


I doubt it. As the designs for the Exploration Upper Stage show, you
can cluster modern RL-10 engines to better effect. Modern RL-10 engines
have more thrust, have larger bells, are generally more efficient than
the early RL-10 used on the original Saturn IV stage.

The fact is, the J-2X was only really needed for Ares-I due to the fact
that they needed very high thrust for the second stage and due to the
small diameter of the five segment SRB first stage, there simply was no
room for a cluster of more efficient RL-10 engines.

Even the Northrop Grumman Omega launch vehicle will use dual RL-10
engines in its upper stage. They are able to do this because underneath
isn't a single solid stage, but two large solid stages (same diameter as
Ares I's five segment SRB, but shorter) *plus* additional solid strap-
ons!

https://www.spacelaunchreport.com/ngl.html


At any rate, here is a very cool web page which details the evolution of
the RL-10 engine:

https://www.b14643.de/Spacerockets/S...gine/index.htm

One of the great innovations on the RL-10 was the addition of an in
flight extensible nozzle. This allows for much higher expansion ratios
while not requiring a longer interstage in the launch vehicle's design,
saving mass on the launch vehicle.

According to Wikipedia, the "EUS will use the new RL10C-3 version, the
biggest and most powerful of the RL10C-X engines".

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.
 




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