ESA, the CEV and the Soyuz

[gaetanomarano]

<br />since I talk of new spaceplanes, LSAMshenzhou, moonrovers, etc... some thinks I'm already mad...

 

[radarredux]

Apparently you guys finally drove SG insane.

 

[nacnud]

<font color="yellow">Apparently you guys finally drove SG insane.<br /><br /><font color="white">Ooops sorry <img src="/images/icons/frown.gif" />. <br /><br />One more question S_G: if I bolted the CEV to the S-IVB and made a submarine what time would it be in Calcutter?</font></font>

 

[nacnud]

Ok it worked out how to translate the gobbledygook.<br /><br /><font color="yellow">S_G 1:<font color="white">"Ok the new details are released in Spring, but do you have a specific date?" <br /><br />No <br /><br /><font color="yellow">S_G 2:<font color="white"> "Orbital module as well or more like below?" <br /><br />yes, like you show. no orbital module. <br /></font></font></font></font>

 

[shoogerbrugge]

can anyone explain me why the CEV won't have an orbital module. I always thought it was rather basic logic that you want your decend module as small as possible. Since that would decrease the need of a large heat-shield, and thus decrease the whole need for upmass. I always thought that dividing the spacecraft in 3 dedicated modules would increase flexibility and decrease total weight, or am I missing something?<br /><br />What is the advantage of a 2 module CEV compared to a 3 module Soyuz/SenZhou

 

[nacnud]

This is a pure guess but perhaps because the CEV currently always docks with another vehicle (LASM, ISS etc) for extra space it isn't needed. Also if the CEV is to be reused the lack of an orbital module increases the ammount reused.<br /><br />Then again there is always the 'not invented here' problem plus no US craft has had an orbital module. <br /><br />Mind you I would have put one in, but I'm no rocket scientist <img src="/images/icons/smile.gif" />

 

[tomnackid]

Apollo was to originally have an orbital module (some say the Soviets "stole" the idea--I dunno about that--its a logical approach and could easily have been invented independently) but Max Faget said that during development for safety and convenience more and more activities were being proposed as taking place in the command module. Eventually the orbital module became superfluous.

 

[mcs_seattle]

nt

 

[JonClarke]

Most biconic entry designs actually enter in with a significant nose up attitude, much like the Shuttle. Finless Kliper is essentially a biconic , and yes, it has swivling seats.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[gofer]

The *orbital* module of a spacecraft is a rudiment of the bad olden days of space races when engineers had to squeeze the last ounces of weight from the return capsules which also affect the weight of the parachute systems, and stuff people into tin cans as tight as they could. And a reflection of old technological limitations. A Kludge, in software speak. It also makes sense as a poor man's lame space station, i.e. you don't have a proper station to dock to after the launch. If your architecture is stationless (the Moon, whatever beyond) than the *orbital* (key word) module is pure nonsense altogether. Note that the latest Klipper has dropped the OM as well. (and good riddance, dropping the SM is a mistake though) It is meant to be a self-containing vehicle (if it wasn't for this latest Parom SM kludge) <br /><br />Witness the Soyuz spacecraft as used now... If its SM was capable enough to deliver the craft to the ISS on same day/hour why would you need an OM at all (now it's used as a 'recreation room' for 1 person before getting to the ISS)? Combining them into a single structure is a rational development. As an emergency bakck up? Nope, the Descent module carries the life support+bakcup. And I bet enlarging the SM's tanks would be less of a weight hit than adding an OM. Nowdays, the OM is a silly, outdated idea.<br /><br />The Apollo designers were on the right track and a bit ahead of the time. A single habitable volume + a service module (LEO craft) + optional mission specific modules (an airlock, a manipulator arm, an Lunar transfer stage)...

 

[n_kitson]

<blockquote><font class="small">In reply to:</font><hr /><p>The *orbital* module of a spacecraft is a rudiment of the bad olden days of space races when engineers had to squeeze the last ounces of weight from the return capsules which also affect the weight of the parachute systems, and stuff people into tin cans as tight as they could.<p><hr /></p></p></blockquote><br />Today engineers still have to squeeze our the last ounces of weight. The physics of space flight have not changed. We still cannot afford to send any useless mass into orbit, or return it. When it comes to space craft, the highest functionality for the least mass is critical on both launch and return.

 

[JonClarke]

Your arguments spacks of the bad old days as well - when every US solution was automatically good and every Russian approach bad. <br /><br />The reality is it depends what you want your spacecraft to do. For some missions an orbital module makes sense, for others it does not.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[gofer]

<blockquote><font class="small">In reply to:</font><hr /><p>Today engineers still have to squeeze our the last ounces of weight. The physics of space flight have not changed. We still cannot afford to send any useless mass into orbit, or return it. When it comes to space craft, the highest functionality for the least mass is critical on both launch and return. <p><hr /></p></p></blockquote><br /><br />The physics are pretty much the same, you got that right. These days the squeezing is done for the upmass (e.g. wanna fit as many transponders in those comm sats as you can). <br /><br />The technology has changed though. Even back in the 60s OM-less spacecraft performed wonderfully in LEO missions and with space stations (including space station repair) and landing was no problem. The landing technology *has* improved since then.<br /><br />BTW, arguing from your position: why send the useless mass of the orbital module into the orbit? In the case of the Soyuz, do you know what's in it and why it's there in the first place?

 

[gofer]

<blockquote><font class="small">In reply to:</font><hr /><p>Your arguments spacks of the bad old days as well - when every US solution was automatically good and every Russian approach bad. <br /><br />The reality is it depends what you want your spacecraft to do. For some missions an orbital module makes sense, for others it does not.<p><hr /></p></p></blockquote><br /><br />Sorry, but you may be projecting? I never said in my arguments that Russian (44 years old Soviet, actually) solution is automatically bad. Actually, the Russian solution, the Klipper, actually seems to have caught on with the times and lost the OM. <br /><br />I said it's outdated now, and that the Apollo engineers had a better idea. On technical grounds. Nothing personal or political. (btw, I am Soviet/Russian and have a healthy doze of respect for many engineering solutions of the old USSR, but I also understand the (tough) conditions that bourn them; memoirs, and accounts help) For both -- out-of-LEO and station bound work.<br /><br />The OM on the Souyz is a rudiment of the days past. It's nothing to be ashamed of, it's just a past requirement of minimizing the down mass (rumor has it - Korolyov gave out bonus stipends for every ounce of mass removed from the descent module of the Soyuz, but there was a piece of an old railroad rail to balance out the COG!) And some others.<br /><br />You actually gave the best support for my 'arguments': "For some missions an orbital module makes sense, for others it does not. " The base config minimum is the best engineering solution, and if the 'extra' is optional (i.e. makes sense sometimes) it's not made a part of the base system. <br /><br />And I just can't think of any modern day missions where an Orbital Module would 'make sense'....

 

[nacnud]

In the Soyuz the OM contains the toilet, docking mechanisum, the door to get in the thing and some of the life support, all of which you can do without for an hour or two as you decend, and not really worth saving if it can be replaced for less than $1,500 per lb.<br /><br />I tend to think that OM make alot of sense for spacecraft, especialy when trying to keep costs down. Only a full reuseable, high flight rate carft should be without <img src="/images/icons/smile.gif" />

 

[gunsandrockets]

"The large crew module is needed for the 6 person crew (ISS and Mars missions). The CLV can not lift the large CM and a orbital module."<br /><br />If the 6 person specification for the CEV crew module is just for 'descent module' jobs (ISS lifeboat), then the CM is still awfully roomier than the descent module of the Soyuz.

 

[gunsandrockets]

"I tend to think that OM make alot of sense for spacecraft, especialy when trying to keep costs down."<br /><br />Exactly right. Plus the OM enables the spacecraft to have an airlock for free. <br /><br />The Soviets showed the same care in keeping the Soyuz weight down that Grumman showed in keeping down the weight of the Lunar Module.

 

[gunsandrockets]

"I said it's [Soyuz configuration] outdated now, and that the Apollo engineers had a better idea."<br /><br />I have to disagree. The Soyuz configuration with it's minimalist descent module + large orbital module, compared to the Apollo command module, provides more living space for the crew even though the total mass is less. That's quite an achievement.

 

[gunsandrockets]

"The CEV does not have a airlock."<br /><br />I suspected as much considering the current Apollo 2.0 incarnation of the CEV. But that doesn't mean the CEV couldn't or shouldn't have an airlock. The earlier LockMart lifting-body CEV of May had an airlock. And an airlock is a feature easily and cheaply accomodated by using the Soyuz configuration with it's orbital module.<br />

 

[gunsandrockets]

"The problem is weight. The CLV can only lift the CEV as it is. "<br /><br />The problem with weight is from using the Apollo 2.0 capsule. If a Soyuz 2.0 was chosen instead the CEV could be lighter plus have an airlock as a freebee bonus.<br /><br /><br />

 

[dobbins]

There are no freebies. One of the reasons the Russians are dropping the Soyuz is the complexities an orbital module adds to the the LES.<br /><br />An airlock won't be needed for most missions the CEV is intended to fly. If some future mission profile requires an orbital module, say a construction project like the ISS, then a reusable module that remains in a parking orbit until needed can be launched. Then the CEV could dock with the module, carry out it's mission, and undock prior to reentry leaving the orbital module ready for it's next mission.<br /><br />No design is perfect, they all involve tradeoffs. The best design is the one where these tradeoffs work best for the missions that the vehicle is intended to fly.<br /><br />

 

[lampblack]

<font color="yellow">There are no CEV missions that require a airlock. Any contingency EVA would be performed by depressurizing the crew module and going out the side hatch.</font><br /><br />Which begs the question, I guess: how would they arrange to depressurize the crew module with six people onboard? Would they carry contingency spacesuits for everybody?<br /> <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>

 

[dobbins]

The Soyuz shroud is more complex than the LES cover that protected the Apollo CM, it has to cover both the OM and RM. The LES is attached to the shroud which has to lift the OM and the RM away from the rocket, then jettison, then the shroud has to release, then the OM has to be jettisoned so the chutes on the RM can be used. Far more complex than the Apollo LES lifting the CM and it's protective cover, then releasing the CM from it's cover.<br /><br />

 

[JonClarke]

"There are no freebies. One of the reasons the Russians are dropping the Soyuz is the complexities an orbital module adds to the the LES. "<br /><br />If complexity were such a problem i doubt they would have chosen this configuration 40 years ago, or persisted with it for so long. The whole system works as works well.<br /><br />We also don't know that the Russians are dropping Soyuz. If past pratcice is anything to go by, Aoyuz may well continue in production in parallel with its replacement.<br /><br />Lastly, the design of the "replacement", Kliper, has not been frozen. Several variants do have an orbital module.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[dobbins]

A replacement for Soyuz or a US capsule using Soyuz technology is NOT in production and that means the more complex LES will have to be mastered all over again for a new design. It's better to avoid Mr. Murphy and his law by following KISS.<br /><br />