Shuttle Design/ Build 101

[mrmorris]

<font color="yellow">"From what I can remember, the space shuttle was originally proposed..."</font><br /><br />You obviously didn't take the time to read the Astronautix link that nacnud put in the thread about six posts back in order to refresh your memory. You are remembering incorrectly.<br /><br />Read a book or three on the history of the manned space program and stop relying on a 'Halman History' that has numerous inaccuracies when compared to what actually took place. A few months back I read four back to back within a matter of a few weeks -- with copyright dates from the late 70's to 2001. The differences in historical perspective on the shuttle program were immense, with one being written while the shuttle was still being built; a second soon after it started flying; the third soon after the challenger disaster, and the last a fairly recent prespective (albeit before the Columbia disaster).

 

[vogon13]

Way back in the mid sixties, an entire Atlas missle (except for the dual dropaway engines) was lobbed into orbit.. Granted, it was virtually without payload, but almost everything you saw on the pad at liftoff wound up in space. This was accomplished without composite anything, the fuel was not LH2, and all the engineers used slide rules. What is the FREAKING hold up on figuring out SSTO!!!!! Thanx for letting me vent. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[nacnud]

<font color="yellow">What is the FREAKING hold up on figuring out SSTO!!!!!</font><br /><br />Getting it back down again, add a heat shield an your payload drops to almost zero, that’s if you make orbit at all.<br /><br />If you’re thinking of an expendable SSTO then that is currently possible but it is much more efficient to increase the payload through staging as all current ELV do.

 

[mrmorris]

<font color="yellow">"What is the FREAKING hold up on figuring out SSTO!!!!! "</font><br /><br />In extension to what nacnud said: SSTOs are certainly possible -- with ridiculously small payloads. They can be compared to a car where the trunk and the rear seat have been eliminated in order to fit in extra gas tanks. <br /><br />Would such a car be possible to build? <br /> Certainly. <br /><br />Would it have the fuel to go a really long distance?<br /> Sure. <br /><br />Does it make any sense whatsoever to build such a car? <br /> Not a bit.

 

[tap_sa]

There are at least three problems with SSTO:<br /><br />1) Fuel tank weight. No matter how many stages, the rocket will basicly be just a big tank of fuel. If you don't do staging then you haul all tank structure to orbit even if it's mostly empty during flight, most of the fuel will be spent very early. Atlas minimized tank empty weight by replacing structurally rigid tanks with pressurized balloons. If I remember correctly von Braun disliked this idea but had to bear with it because at the time Atlas was the only vehicle capable to put Mercury into orbit. This dislike appears to remain in NASA, the idea of vehicle staying in shape just by pressure is sooo scary.<br /><br />2) Atmosphere vs vacuum. If you design an engine that works well on sea level it's efficiency is seriously impaired in vacuum, and vice versa. Then you have to make some sort of compromise.<br /><br />3) Thrust at lift off and near orbit. When the rocket picks up speed and gains altitude it spends fuel and gets lighter all the time. If thrust remains the same acceleration increases. At some point it becomes too high for even unmanned missions. To keep the acceleration within limits you need to throttle down engines and/or shut them down. It's better to shut down engines and use smaller ones because throttling down usually means loosing some efficiency and you'd need very deep throttling down to 20% or so.<br /><br />Atlas solves 2 and 3 by having high power boosters designed for low altitude and then dropping them off quite early in the flight. That way you don't have compromise the efficiency and haul unnecessary thrust power to orbit.<br /><br />A modern stage and a half vehicle (SHTO?) might be nice for LEO missions, servicing ISS and future space motels but going any further calls for upper stage. You don't want to send the whole craft to GTO.<br /><br /><br /><br /><br />. <br />

 

[halman]

mrmorris,<br /><br />I first heard about the space shuttle in 1972, during a science program. The vehicle that was described is very similiar to the drawing in the Astronautix article dated 1971. Payload specifications were somewhat vague, but definitely less then 10 tons. This was to be a totally reusable vehicle, with a 'flyback' booster, no external tanks, no Solid Rocket Boosters. The concept was directly descended from the lifting body experiments called Dyna-Soar.<br /><br />The next time I saw a piece on the shuttle, it had bloated into something very similiar to its current form. This was in late 1973, in Aviation Week and Space Technology.<br /><br />The shuttle as it was originally proposed was never considered the do-it-all heavy lift launch vehicle that we ended up with. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[halman]

vogon13,<br /><br />Every design for a Single Stage To Orbit launch vehicle that I have seen is HUGE. Minimum 1,000,000 pounds to orbit payload, with vehicles weighing around 10 to 15 million pounds at launch. The first one that comes to mind is the 'Big Onion', which was proposed in the late 1960's. Vertical take off, vertical landing. <br /><br />The usual opposition to a Heavy Lift Launch Vehicle in the 250,000 to 500,000 pound payload category is that there is no requirement for payloads that large. Yau can square that argument for an SSTO vehicle with a 1 million pound capacity.<br /><br />Of course, if we actually are serious about returning to the Moon to stay, then larger launch vehicles will have to be built. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[mrmorris]

<font color="orange">halman 11/27/04 06:13 PM</font><br /><font color="yellow">"The original design concept of the space shuttle was for a vehicle about the size of the current shuttle, with a small payload capacity, which was carried to an altitude of about 20 miles by a fly-back booster."</font><br /><br />The original concept was about the size of the current shuttle -- but a smaller payload. OK.<br /><br /><font color="orange">halman 01/18/05 06:22 PM</font><br /><font color="yellow">"From what I can remember, the space shuttle was originally proposed as a small vehicle to carry personnel to orbit, to be used in conjunction with step-rockets, which would carry the cargo. "</font><br /><br />The original concept was much smaller than the current shuttle -- no payload, just personnel. OK.<br /><br /><font color="orange">halman 01/20/05 05:06 AM</font><br /><font color="yellow">"The vehicle that was described is very similiar to the drawing in the Astronautix article dated 1971. Payload specifications were somewhat vague, but definitely less then 10 tons. <br />... The next time I saw a piece on the shuttle, it had bloated into something very similiar to its current form. "</font><br /><br />The original concept was much smaller than the current shuttle -- smaller payload, then grew in size to the current design. OK.<br /><br />You can't even remember your own posts. Why should anyone give any credence to your memory of the early 70s?<br /><br />In 1971, the shuttle was at about the same stage of 'development' that the CEV is now. NASA had a broad set of specifications for it that numerous vehicle types would fit. From the Astronautix article:<br /><br /><i>"The requirements called for "Integral Launch & Re-entry Vehicles" having a 12-crew capability, 720km re-entry cross range, and a <b>2.268-22.68t payload</b> capability by 1974. </i><br /><br />They had only pinned down the payload specs to an order of magni

 

[craigmac]

I think the original objective of this topic was to come up w/ solutions and improvements to the current design...

 

[mrmorris]

<font color="yellow">"...original objective of this topic..."</font><br /><br />Understood. I made only a single post regarding the <b>topic</b>. The remainder were in response to halman's posts. In my one post, I was trying to indicate just how <b>much</b> of an improvement would be required in a Second-Generation Shuttle to make it truly efficient (as opposed to simply being less inefficient than the current shuttle). However -- I'll exit stage left and leave the topic alone henceforth.

 

[marcel_leonard]

<font color="yellow">mrmorris-<br />I still hold to the opinion that replacing it with something much smaller and simpler will allow for a better use of NASA's budget and advance the technology of manned spaceflight more rapidly. With less money spent on operating costs of existing systems, more money can be spent on development of new technology. R&D, after all, is the best part of NASA. They have the money to spend billions developing the tech that the private sector can then make use of. For NASA to be most effective, they have to constantly be on the cutting edge -- always trying something new. The shuttles aren't new, and they cost so much to run, that NASA has much less money to do this. <br /></font><br /><br />How about keeping the current shuttle design for heavy payload deliveries, and creating a smaller lighter orbiter for crew transport to and from the ISS? Maybe even one that is even SSTO? <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[nacnud]

Been tried, got cancelled remember the OSP

 

[tap_sa]

<font color="yellow">"How about keeping the current shuttle design for heavy payload deliveries"</font><br /><br />Would the shuttle be cheaper than EELVs? I doubt.<br /><br /><font color="yellow">"a smaller lighter orbiter for crew transport to and from the ISS"</font><br /><br />G-X3 + Falcon !

 

[marcel_leonard]

Sorry I couldn't reply earlier finals week. All things being considered; you can't tell me that after almost thirty years of operation that NASA couldn't upgrade the orbiter to a lighter/faster/safer version of it's self [ie. May 2005 return to flight status; plus backup recovery crew]. Maybe they can contract the guys from MTVs Pimp My Ride? I bet they could a least design a more user freindly LCD touch tone control panel for their flight deck. <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[marcel_leonard]

Here is an interesting article on Zane Pinckey. <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[craigmac]

What would it take an SSTO that could travel at the following escape velocites?<br /><br />Flight Plan<br /> speed required <br />Earth to LEO (low Earth orbit) 17,000 mph <br />Earth to Earth escape 24,200 mph <br />Earth to lunar orbit 25,700 mph <br />Earth to GEO (geosynchronous Earth orbit) 26,400 mph <br />Earth to solar escape 36,500 mph <br /><br />I'm for specs on what type of materials should it be made out of? What type of fuel? Basically the overall configuration of the SSTO...<br />

 

[dan_casale]

The current proposals for a space tether call for it to be anchored to an ocean going platform like an oil drilling platform. That way it can be moved to avoid all the weather problems. see www.liftport.com for more information.<br /><br />As I understand, there are several sites in the ocean that almost never have storms.

 

[dan_casale]

Your are correct. My oversite.

 

[nacnud]

Suprisingly enough the site does not <i>have</i> to be on the equator, the lowest forces are experiened at the equator but it could be built elsewhere. In which case the elevator would be curved when view from the side (north/south) with the most pronounced curve nearest the ground.

 

[nacnud]

OK this is what I mean.

 

[nacnud]

<font color="yellow">BTW did you mean curved when viewed from the east or west? </font><br /><br />Yes probably.

 

[marcel_leonard]

Call me naive but I don't think that at present we have cable technology that could withstand the extreme amounts shear/tenstile stress/strain for a thether system like this one to work. Not to mention orbital and gravitational mechanics which would snap it like a thread...... <div class="Discussion_UserSignature"> "A mind is a terrible thing to waste..." </div>

 

[nacnud]

Well we don't have the technology for any kind of space elevator yet. I admit that an equatorial site would be perfered to mimimise the forces on the cable but in theory it doesn't have to be there, you just need a better kind of unobtainum. <img src="/images/icons/smile.gif" />

 

[fatjoe]

Affordable Space Delivery System ASDS is more likely to win out; as an alternative shuttle propulsion with a combination of scramjet/plasma propulsion engine...

 

[craigmac]

Sometimes I think we are living in a new modern day dark ages were the Church/State having convinced the whole of society that it is impossible to reach orbit affordably. The same way a millenium ago the Church/State convinced society as a whole that the Earth was the center of the Universe...