Question about shuttle orbiter reentry

[qso1]

The big problem with adding boosters is that at launch, your booster deadweight eats up much of your payload capacity. Then where do you physically locate them? A location that has to be able to facilitate safe firing (No plume impengement on the orbiter) and separation. <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>

 

[vogon13]

Indubitably!<br /><br /> <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>

 

[spacester]

Please note that I said <font color="yellow">In theory – wholly impractical, I'm sure – you could even strap some solid rockets onto the orbiter and come in a lot cooler. </font><br /><br />Please note the "wholly impractical" part. And that it presupposes that the solids got to ISS by some other, much less expensive means.<br /><br />It's a thought experiment for an old and well traveled topic, submitted after the initial responses were given. Do we still do that kind of thing around here?<br /><br />edit: I had other qualifying statements in that post that are being ignored . . . <br /> <div class="Discussion_UserSignature"> </div>

 

[qso1]

No problem.<br /><br />spacester:<br />It's a thought experiment for an old and well traveled topic, submitted after the initial responses were given. Do we still do that kind of thing around here?<br /><br />Me:<br />Sure we do. Different responses for different folks, mine tend to come off a bit on the serious side so bear with me. <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>

 

[qso1]

spacester:<br />edit: I had other qualifying statements in that post that are being ignored...<br /><br />Me:<br />My apologies on those I may have ignored. <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>

 

[spacester]

No problem. My apologies if I'm over-sensitive . . . <div class="Discussion_UserSignature"> </div>

 

[halman]

spacester,<br /><br />I can think of another loophole. It is not practical at the moment, but the day may come...<br /><br />If a tether could be run out some distance, with a remote controlled 'sled' at the end, the 'sled' could do the aerodynamic braking, transfering the change of velocity to the shuttle via the tether. I described this idea in another thread, some time ago, and called it a 'space anchor'. Someone told me that it had already been thought of, which made me feel good all over. We just don't have the technology for a tether that would work yet. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[vogon13]

Tether + lifting form ballute = Triton / Pluto lander<br /><br /><img src="/images/icons/smile.gif" /><br /><br /><br /><br /> <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>

 

[CalliArcale]

I must say, it's fun reading some of the suggestions coming up in here. They're actually a lot more practical than the tired old impractical ones that used to come up. <img src="/images/icons/wink.gif" /> It's refreshing! Thanks, everybody!<br /><br />The aerobraking idea is interesting. Essentially, that's already what it's doing, but could it be dragged out a lot more? I suppose the biggest penalties there, besides crew consumables, are:<br /><br />* the payload bay doors probably need to be closed, and that renders the radiators inoperable; there is a limited supply of ammonia for the flash evaporator system that cools the Orbiter with the doors closed<br /><br />* the percentage of mission spent doing useful things is much smaller; so is it cheaper to have less TPS, or to have a faster reentry?<br /><br />It's too bad the Shuttle's so damn big. That's the main limiting factor, it seems. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[bdewoody]

Over the years we have been putting humans into soace I have come to believe that until or unless we can neutralize gravity aka. anti-gravity space travel will not spread to the general public. That is unless we discover some new material that can deflect the heat and not be so vulnerable to impact damage. It's probably the ride up that is most dangerous but I have a feeling that re-entry scares people more, what with that firey halo they see out the windows. <div class="Discussion_UserSignature"> <em><font size="2">Bob DeWoody</font></em> </div>

 

[josh_simonson]

Momentum exchange tethers can drop payloads off to re-enter at less than half orbital velocity, the tether gains orbital energy in the procedure that can be used to lift the next payload. This reduces the need for thermal protection on descent, and significantly improves the mass fraction on ascent. It isn't anti-gravity, but it's feasible with current technology/physics.<br /><br />If the sub-orbital tourism industry takes off we may well see such a system developed since the upgrate from suborbital launches to tether interceptor isn't nearly as great as to a full orbital craft.

 

[yoda9999]

By tether and sled, do you mean like a parachute?<br /><br />BTW, do the shuttle astronauts feel the heat during re-entry?

 

[willpittenger]

How much of that was due to the TPS and how much due to really good cooling systems? Also, did Apollo, Gemini, or Mercury astronauts feel anything? <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>

 

[qso1]

bdewoody:<br />It's probably the ride up that is most dangerous but I have a feeling that re-entry scares people more, what with that firey halo they see out the windows.<br /><br />Me:<br />More people probably do fear re-entry but there will be more than enough who are willing to go despite that. On the shuttle re-entry, its mostly a pinkish glow. The fire effects often seen in one of the shuttle vids is on the tail as viewed through the overhead windows at an angle. That can only be seen on the flight deck. Mercury thru Apollo probably had more fire effects due to having ablative heat shields.<br /><br />What will keep the general public at bay is cost. At least unless or until space tourism demonstrates its viability and costs come down for average income folks. <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>

 

[halman]

yoda9999,<br /><br />Well, it would be somewhat like that. But the 'sled' would be a remotely piloted lifting body, only it would be inverted, so that the lifting force pushes the sled down. This force is controled by the pilot to create the most drag possible without burning up the sled. The drag is transferred via the tether to the shuttle, which is slowed without experiencing heating. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[vulture2]

>>>I believe that, if you were to examine the heat signiture of the shuttle during re-entry, the area exposed to the highest temperatures is the belly, the bottom of the vehicle. This is because the shuttle is riding a shock wave, which is protecting it from the plasma its passage through the atmosphere creates. That plasma reaches nearly 20,000 degrees Farenheit directly under the shuttle, but the tiles there are only exposed to about 3,000 degrees. <br /><br />I agree, a blunt body avoids over 95% of the reentry heat because the strong shock wave remains well separated from the surface and carries the energy away. That was the genius of Mercury. Who would have guessed that the best way to reduce the heat of aerodynamic friction is to increase drag tremendously by entering blunt end first?<br /><br />However we agree that sharp leading edges do become very hot; that's why Apollo didn't have them. The Shuttle, however, needed lift at high speed to acieve the specified crossrange. CEV won't have wings, so no crossrange and no runway landings.<br /><br />I think if we ever get a new reusable vehicle, runway landing will ultimately be more practical than landing by parachute. The problems with the shuttle, now that they are better understood, could be avoided in a future design. It could just use a delta wing with better designed RCC or use variable geometry (like SpaceShipOne) to allow a blunt-body entry with less heating, or maybe a replaceable Apollo-type ablaitive on the hotter areas.

 

[vogon13]

------------------<br />blunt end first<br />------------------<br /><br /><br />Nature is already ahead of you here. That's the end of the egg that comes out of a chicken first, too.<br /><br /><br /><img src="/images/icons/laugh.gif" /><br /><br /><br /> <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>

 

[willpittenger]

One idea I had that I mentioned in my Challenger Class Orbiter thread was to use a swing canard. I specified that it should retract onto the top part of the fuselage, which had a thick center with thinner outer sections. Those outer sections also helped with lift. The final part of the lift puzzle I added was a pair of rakes going the length of the fuselage. They served as the lifting body equivalent of those bent wing tips on modern wings.<br /><br />Remeber, I was not creating an orbiter that would launch and land like the STS system. Rather, it would behave more like a conventional plane -- except for the 250 MPH+ ground speeds. Those were needed to take off in the limited runway space that I was willing to put up with. That let me pick up my load at the plant where it was built without requiring special runways. <div class="Discussion_UserSignature"> <hr style="margin-top:0.5em;margin-bottom:0.5em" />Will Pittenger<hr style="margin-top:0.5em;margin-bottom:0.5em" />Add this user box to your Wikipedia User Page to show your support for the SDC forums: <div style="margin-left:1em">{{User:Will Pittenger/User Boxes/Space.com Account}}</div> </div>