An HL-20 question...

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lampblack

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Reading the recent SDC story on Dreamchaser led me to google around a bit on the HL-20 concept.<br /><br />It seemed so promising: a small, nimble horizontal lander that could carry up to 10 people to orbit, with quick turn-arounds due to low-cost maintenance more like a commercial aircraft than an experimental spacecraft.<br /><br />This may be old territory for many folks here, but I'm wondering: How could the Powers That Were in the early 1990s allow such a promising concept to be shoved to the back burner? Can anyone offer any insight -- or at least share a few relevant links? <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>
 
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gunsandrockets

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It probably boils down to NASA having to scrape by on shrinking budgets while still supporting the Space Shuttle money hog. Nothing was left over for promising programs such as the HL-20.
 
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gunsandrockets

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http://www.astronautix.com/craft/mig10511.htm<br /><br />"The spaceplane itself was a flat-bottomed lifting body with a large upturned nose that earned it the nickname 'Lapot' (wooden shoe). The nose design was found to greatly reduce afterbody heating during reentry and was adopted by NASA in its HL-20 proposal of the 1980's."<br /><br />This part is very interesting...<br /><br />"A unique feature of the spaceplane were the variable dihedral wings. These were set at a 60 degree angle above horizontal during launch, orbit, and reentry, where they served as vertical stabilizers. After becoming subsonic, dual electric actuators moved them to a horizontal position, where they served as wings, substantially increasing the lift of the spaceplane for airbreathing operations."<br /><br />...very clever them Ruskies!
 
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vt_hokie

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<i> How could the Powers That Were in the early 1990s allow such a promising concept to be shoved to the back burner? Can anyone offer any insight -- or at least share a few relevant links? </i><br /><br />To use the favorite line of many CEV proponents, "Because it can't go to the moon!" <br /><br />After all, sending a few guys to the lunar surface for a few days is so much more important than establishing safe, routine access to space!
 
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qso1

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vt_hokie:<br />To use the favorite line of many CEV proponents, "Because it can't go to the moon!"<br /><br />Me:<br />Lunar missions were not even being seriously discussed at the time the HL-20 was being proposed. The HL-20 was one of several proposals for inexpensive access to space floating around in the early 1990s. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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nacnud

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The HL-20 lost out to the X-38 because the X-38 was cheaper. In turn the X-38 lost out to the Soyuz because the Soyuz was cheaper.
 
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mattblack

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>>The HL-20 lost out to the X-38 because the X-38 was cheaper. In turn the X-38 lost out to the Soyuz because the Soyuz was cheaper.<<<br /><br />All true. I was dissapointed when HL-20 and X-38 were cancelled. I thought the HL-20 in particular would have been brilliant. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>
 
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qso1

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nacnud:<br />The HL-20 lost out to the X-38 because the X-38 was cheaper. In turn the X-38 lost out to the Soyuz because the Soyuz was cheaper.<br /><br />Me:<br />None of the American proposals were cheap enough to compete with an already existing Soyuz in any case. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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nibb31

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Which is stupid, because it's the reliance on Soyuz that causes the current limitation to a crew of 3. The X-38 was supposed to be a lifeboat for the entire crew of 6.
 
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j05h

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> Which is stupid, because it's the reliance on Soyuz that causes the current limitation to a crew of 3. The X-38 was supposed to be a lifeboat for the entire crew of 6.<br /><br />No, the limited crew is because of the reliance on Shuttle to support larger crews. If in the early 90s, the first redesign had included "Alternative Access", Station would be done and STS retired. The Russian limit isn't Soyuz, but the Soyuz production line (subtle, but different). Soyuz works great compared to the alternatives, and the production line is currently being expanded. The expansion is happening because of (drum roll)... the market demand.<br /><br />It's still disturbingly shortsighted that x38/aCRV was cancelled, because we really need it now. Just like the "cynics" predicted in the late 90s.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
 
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Boris_Badenov

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Money, money, money. Everything they had to spend went to the Shuttle. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>
 
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avmich

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> Soyuz works great compared to the alternatives, and the production line is currently being expanded. The expansion is happening because of (drum roll)... the market demand.<br /><br />Not exactly. The demand was always here; the ability to make Soyuzes wasn't. There used to be 4 flights of Soyuz per year, and it slipped to 2 per year because of the difficult financial situation in Russia. Even commercial flights weren't enough to justify making more flights - mainly because of overhead expences. But now money are flowing more steadily into Russian aerospace, as the government commands bigger budgets; so comes the decision to build 4 Soyuzes per year again.
 
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spacefire

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HL20 and HL42 were ind esign stage while the SHuttle was flying. I'd have thought the Challenger disaster would foster the creation of alternative programs but HLs stayed sort of on the back burner with only minor research being done, till the 90s when everyone forgot about them.<br />Typical government process. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>
 
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qso1

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We may yet see an HL-20 type vehicle again. Either developed by private enterprise or NASA and possibly mounted where CEV is on the CLV. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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nacnud

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You couldn't put the HL-20 on the Aries I (CLV) because of the torques developed by the wings.
 
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vt_hokie

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Why would the torques produced be more of a showstopper than those that must be generated by the shuttle orbiter on the stack?
 
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strandedonearth

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Because the Center of Pressure (Cp) generated by the wings of the HL-20 would be much farther ahead of the vehicle's Center of Gravity (Cg) compared to the Cp/Cg relationship on the STS stack, requiring bigger fins at the base of the vehicle and/or a more robust thrust vector control (TVC) system. For an inherently stable vehicle, the Cp actually has to be BELOW the Cg (Model Rocketry 101).
 
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qso1

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After being told this here by several posters including S_G, I wonder then, after all these years why that was not known when they proposed the Dyna Soar, the Hermes, and HL-20. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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j05h

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The DynaSoar rockets (various Titans) had extremely large control surfaces on the tail, the Titan III version would have sported canard winglets, too. They aren't standard versions of those rockets. According to the Astronautix article, the proliferation of rockets across the US effort (NASA, AF) was one of the reasons for cancellation. <br /><br />Hermes was to fly on Ariane 5, the TVC system would probably be powerful enough to compensate. Not sure about the original HL-20 stack, but SpaceDev's new config is pretty cool. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
 
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qso1

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Those look like various Dyna Soar sketches. And they show that such a configuration must be workable. After all, Dyna Soar actually got to the mockup stage and it seems unlikely a proposal would get that far if instability were an insurmountable problem.<br /><br />I don't doubt the wings cause some difficulty but I just wonder if that difficulty can be safely overcome. I also tend to think that a clustered booster (Titan with strapons) may be a more stable config. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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qso1

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The Titans with the huge fins, I do recall those and that must have been after the original Titan 1 launcher proposal that I didn't recall seeing fins on but I might just be remembering wrong.<br /><br />The Spacedev config, is that the one that's side mounted? If so, your back to the original problem with the shuttle. Maybe the aerovehicle has some other method of dealing with ice chunks. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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j05h

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<i>> The Titans with the huge fins, I do recall those and that must have been after the original Titan 1 launcher proposal that I didn't recall seeing fins on but I might just be remembering wrong. </i><br /><br />Normally the Titans had thrust-vector control instead of fins. The mods required to fly Dyna Soar on Titan seem similiar to what is being argued for CEV/CLV. They are both existing rockets, but once you get into the mods it snowballs.<br /><br /><i>> The Spacedev config, is that the one that's side mounted? If so, your back to the original problem with the shuttle. Maybe the aerovehicle has some other method of dealing with ice chunks.</i><br /><br />Yes, the DreamChaser is sidemounted. It wouldn't have the ice problem because it will use hybrid engines. Not that it won't suffer debris issues, but ice shouldn't be present.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>
 
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qso1

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I didn't get a chance to look at Dreamchaser specs but if its not cryo then ice won't be a problem. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>
 
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