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Post Info TOPIC: CEV vs. HL-20 derivatives
10kBq Jaro


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CEV vs. HL-20 derivatives
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NASA's CEV is going to look awfully antiquated, when private companies start landing their mini-shuttles at airport runways, IMO....


http://www.space.com/missionlaunches/051123_spacedev_dreamchaser.html


Private Spacecraft Developer Settles on New Design


By Tariq Malik, Staff Writer;  posted: 23 November 2005


A private space firm with orbital aspirations has revamped its plans for a crew-carrying spacecraft.


Poway, California-based aerospace firm SpaceDev has a new design for its Dream Chaser vehicle and hopes to offer suborbital rides within two years, with orbital flights to follow.


Instead of deriving a spacecraft from NASA’s X-34 space plane concept, the firm has opted for a blunt-nosed lifting body approach to cut down on reentry heating stresses, SpaceDev chief Jim Benson said in a telephone interview. The plans stem from work SpaceDev performed with NASA’s Ames Research Center to study the use of hybrid rocket propulsion for spaceflight testbeds.


"Because of the X-34’s pointed nature and sharp edges, the high temperatures would meet the limits of our vehicle right at the ragged edge," Benson said, adding that the new Dream Chaser design more closely resembles the Horizontal Landing-20 (HL-20) model studied by NASA’s Langley Research Center. "The HL-20 was a great little vehicle and it’s already designed."


Small enough to fit inside the payload bay of a NASA shuttle with folded wings, the HL-20 Personnel Launch System was slated to carry 10 astronauts (two pilots and eight passengers) or small payloads into orbit, though funding for the program dried up in 1990.


SpaceDev’s take on the small spacecraft would be lighter, seat four people for a suborbital flight and up to six for an orbital trek. The space plane is envisioned to launch atop a launch stack of hybrid rocket engines - like those developed by SpaceDev as part of the SpaceShipOne Ansari X Prize entry - and make a runway landing back on Earth, according to its designed flight profile.


"We don’t use cryogenic liquids, so there’s no ice or foam to worry about, and it’s non-explosive," Benson said of the current design.


Benson said that with $20 million or less and about two years, SpaceDev could have a four-person suborbital Dream Chaser vehicle ready for flight. Given three more years, as well as $100 million, and the firm could develop an orbital variant, he added.


SpaceDev hopes its design will enable the firm to participate in commercial cargo and other services to support the International Space Station (ISS), and could aid future Moon expeditions as well. Last week, NASA chief Michael Griffin said private supply ships with their own launch services will be vital to deliver future cargo to the ISS.


"We’re keenly interested in that," Benson said, adding that an orbital Dream Chaser could haul one ton of cargo - with limited crew - to the ISS. "Once we get into orbit, you can really make use of it. It doesn’t matter if it’s going to the space station, habitat modules or what…what we need is low-cost access to low Earth orbit."



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GoogleNaut


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Yeah, I read this last night too. I think its wonderful that SpaceDev is picking up the reins as it were--I think a mini shuttle makes good sense. It allows crews to fly to and return from space. It allows spacesuited workers to manipulate payloads. It also allows a lot more contingency leeway--a smaller, more responsive vehicle can be reserved for a 'hot launch' if an emergency requires a rescue. I think the PR value of such a system has been entirely overlooked too.

I am also an advocate of the CEV--it too makes sense, because crews returning from interplanetary missions will have a much higher delta-v to dispose of. A ballistic capsule, versus a minishuttle, is able to return at 11 km/s, the entry speed of the Apollo's. The high heats of this entry regime negates the benefits of a minishuttle with reusable TPS--only ablative heatshields can dissipate the extremely high heat loads of high entry speed.

So I would strongly argue that we need both.


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larry


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Sadly NASA has turned into a welfare program for engineers. It's not that NASA engineers aren't good - rather the bureaucracy acts as damping rods on intelligence.




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john fraz


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The KISS principle (form follows function)
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K.I.S.S. = "Keep It Simple, Stupid"

One thing to keep in mind, (maybe it's my irrational dislike of most things to do with the Space Shuttle), is that this wouldn't be a "mini-shuttle". No payload bay, no multi purpose mutually contradictory design requirements that add weight and complexity & cost so we spread more graft $ around to more congress-critter's districts.
The ESA Hermes was a "mini shuttle", (designed by committee) and look what happened to it; cut because it was growing from a safe crew launcher, getting politicians and contractor's favorite pet projects added into it, overgrowing any sane booster development schedule whether or not any of these new design features were needed. Like the Space Shuttle, things were added for the express purpose that they made it more expensive, so more politicians had a stake in it with jobs in thier districts. (there needs to be something for politicians to advocate spending money on that doesn't involve getting our nations into wars or cutting the hamstrings of our space programs...)

You don't take a crew "shuttle" spaceplane and make it operate in LEO for 2+ weeks running experiments and testing long-term effects on astronaut's of microgravity! It doesn't need any more than a few days on-time provisions, and probably not even that. Enough to get up, deliver crew and payload (food and mail and small experiment packages) through the airlocks, and come back down to be turned around for the next flight (a "shuttle" by definition... look it up, if in doubt)

BTW, you also wouldn't want to take a ground-LEO-ground safe crew launcher "shuttle" into interplanetary trajectories. It only has provisions to last a few man-days as a ferry/taxi, so you can't live in it, it desn't have a suit-up airlock or anything else -let alone a heat-shield that could take interplanetary speeds.

OTOH, why would you build a "CEV" or whatever you want to call it, for safe ground-LEO-ground taxi service or ISS lifeboat service, and give it a heat shield that could take an 11km/sec re-entry? It's not an interplanetry or Lunar surface expedition ship. I've never heard a good explanation for NASA and the Shrub White House's claims that one ship could be designed to do all that. That entire early "plan" looked fishy to me: like it was designed by a White House PR clerk who had nothing to do with engineering or aerospace. "well, a spaceship naturally is able to do all those things, isn't it?" And our CEV as of today is still clinging to those unnecessary design requirements, and facing multi-mission problems and design difficulties...


If I can later, I'll edit my HL-20 evolution thread (page 2 now) and add it all as replies to this thread.

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John


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RE: CEV vs. HL-20 derivatives
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No payload bay, no multi purpose mutually contradictory design requirements that add weight and complexity & cost so we spread more graft $ around to more congress-critter's districts.


I think there is very little "graft" in this whole thing, former congressman Cunningham aside.  But, in a democracy you are going to have to spread the money around in order to get political support.  The requirments issues is driven by shortage of money/projects.  When everyone could have there own specialized system one didn't have so much of this.  Today if you don't get your requirments on the one system that is getting built you just out of luck.


As for the CEV's heatshield requirements, well yes the whole plan is to go back to the moon.  Buzz Aldrin even has a Mars idea where it is a key component.  The current NASA plan is to get back to "exploration" rather than just a transportation service. 


In a way this goes against my bias which is for a big technology push.  We haven't make a major advance in operational (vs lab) space propulsion since the mid '60s, i.e. the LH2-LOX rocket engine.  The Shuttle is a prototype rather than a true spaceship but is an important step in the right direction.  Clearly another step is required now.  I think that it does give us a lot data on what work well and what doesn't.  I've tended to favor the hybrid airbreathing/rocket concept for SSTO vehicles.  Perhaps that isn't the answer but we need to get to the level of a single vehicle with significant throw away parts that can fligh multiple mission before depot level maintainance.   I would guess that if we could fly ten mission for the support that one Shuttle mission requires that would do. 



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