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