"New" CEV pictures

[halman]

Solarspot,<br /><br />The term 'spacious' refers to excessive or large amounts of room or space in a given structure. It is not a term I would have applied to either the Gemini or Apollo capsules, as both provide about the same amount of room as sitting in the front seat of a car. A station wagon, in the case of Apollo, and a compact in the case of Gemini. The consoles were only about a foot or so away from their faces. Only when the center seat had been stowed and the two astronauts were in the Lunar Excursion Module did the remaining astronaut have any excess room.<br /><br />Remember, this vehicle is supposed to support a crew of 6 for a number of days. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[holmec]

yeah something like that....very nice pic. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[jimfromnsf]

"Only when the center seat had been stowed and the two astronauts were in the Lunar Excursion Module did the remaining astronaut have any excess room. "<br /><br />Not true. There is more volume than just the seat area. There is the lower equipment bay, where two astronauts could stand. This is "aft" of the crew seats. This volume is access even before the middle seat is stowed<br /><br />Also there is the volume underneath the seats.

 

[solarspot]

halman;<br /><br />Just nittpicking as some would call it... I reffered to Gemini as "spacious enough" to mean that... with costs of transportation to space... I wouldn't ask for more space then that unless I was paying a hundred-million dollars my seat. Personally I do consider Apollo to be slightly larger than necessary for the task it had to perform, although I submit I may easily be wrong on that last statement due to my limited knowledge about Apollo's interior. <br /><br />But I suppose if I designed every manned spacecraft for the next 2 decades... astronauts would end up crammed into spacecraft like sardenes (sp?) for days on end, routenly... Maby it's for the best that I don't work on manned spacecraft designes lol.<br /><br /><br />

 

[thereiwas]

Gemini was roomy compared to the Soyuz re-entry section.

 

[jimfromnsf]

Not really. <br />Soyuz 3.5 m3<br />Gemini 2.55 m3

 

[j05h]

<i>> The CEV can directly return to earth from the moon. Going from the moon to LEO and rendezvous with a vehicle would take a large amount of propellant which weighs a lot more than a heat shield </i><br /><br />That is not conclusive, especially with a working ISRU infrastructure. The mass of propellant to drop into LEO can be less than a heatshield, depending on assumptions for each. Realistically, they are similar in mass terms, there is not an order of magnitude difference but a percentage. Economically, putting something up there and reusing it is smarter than dumping it in the ocean. CEV relies on an untried rocket and fickle budget - I can see Lockheed finishing it or fielding some kind of capsule, but think the flown product is going to be a lot different than currently described.<br /><br /><i>> Also there is the phasing requirements to allow rendezous.</i><br /><br />Phasing is a serious issue for any return-to-LEO designs. Could a secondary high-Isp engine help with this, or is it all in the timing? It seems like it would almost make sense for a tug/capsule to meet the returning craft in a planned higher orbit then proceed to a station or reentry. Or the capsule could launch after LEO return to ensure proper orbits. A SeaLaunch type system would really help in this regard.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

<The mass of propellant to drop into LEO can be less than a heatshield, depending on assumptions for each. Realistically, they are similar in mass terms, there is not an order of magnitude difference but a percentage.><br /><br />Hmmm...for propulsive braking into LEO from lunar return you would need a delta-V of around 3 km/s. Using Apollo style storable propellants with an ISP of 310 seconds you would need a mass ratio of around 2.7 to achieve that much delta-V.<br /><br />Okay let's try a best case of nuclear propulsion with an ISP of 900 seconds. Even then you are talking about a spacecraft mass of 30% propellant. Not very efficient at all.<br /><br />A spacecraft which aerocaptures into LEO wouldn't need parachutes or the heavy heat shield of a more typical direct-entry capsule. The mass of a heatshield would probably be less than 15%. That is a huge difference in mass compared to propulsive braking.<br /><br />Aerobraking also has a mechanical reliabililty advantage of being a (relatively) passive system.<br /><br />Any reusable manned spacecraft for travel between the Earth and the Moon is going to use aerobraking. The mass advantages are too great to give up.<br /><br />For unmanned cargo though, propulsive braking would be logical for a slow electric-propulsion reusable orbital tug. <br /><br />

 

[gunsandrockets]

Cool!

 

[gunsandrockets]

<Gemini was roomy compared to the Soyuz re-entry section.><br /><br />The Gemini reentry vehicle and the Soyuz descent capsule are pretty much the same in terms of living space per crew member.<br /><br />As I recall the numbers from astronautix.com give a living space of around 2.5 cubic meters for the Gemini and 4 cubic meters for the Soyuz. That works out to 1.25 cubic meters per person in the Gemini and 1.33 cubic meters per person in the Soyuz. Not much to choose from between those.<br /><br />I will grant you that the Soyuz seats are more cramped than the Gemini seats, with the way the Soyuz crew must bend their legs and tuck in their feet.

 

[thereiwas]

I was thinking of the shoulder room in Gemini, due to the way the seats angled apart. In Soyuz they are wedged in like sardines.

 

[jimfromnsf]

The Soyuz seats are angled apart also

 

[j05h]

<i>> Hmmm...for propulsive braking into LEO from lunar return you would need a delta-V of around 3 km/s. Using Apollo style storable propellants with an ISP of 310 seconds you would need a mass ratio of around 2.7 to achieve that much delta-V. </i><br /><br />2.7 is between 70-80% of the vehicle being fuel, right? While a big number, and possibly more expensive (for now) than a heat shield, it shouldn't be dismissed out-of-hand for a Moon or Mars return craft. This makes the most sense if it has ISRU on the other end and a tug or fuel depot in LMO/LLO. The true enabler would be a working passenger RLV to LEO. Moving toward a propulsive braking architecture early also allows you to use the same vehicles for flights to and from Mars, Moon and Earth. Otherwise we are often talking about specialized heatshields for two and propulsive braking for the Moon. Is there a generalized artchitecture that would allow this? Three planets for the price of one? <img src="/images/icons/wink.gif" /> This might actually be an argument for the ARES V or other HLV - putting up more robust spacecraft that can (with several fuellings) travel throughout the inner solar system and aerobrake anywhere and prop. brake otherwise? Critical to this would be plentiful fuel (ISRU) or new propulsion tech.<br /><br />The technologies to concentrate on include reusable heatshields (can you split the difference - metal heatshield/structure and some braking?), ISRU development (critical) and some kind of aerobraking demonstrator. Perhaps fly a capsule into a highly elliptical orbit and practice aerobraking remotely before trying with people. This can be done and has been proposed experimentally. <br /><br />Definitely have to agree on the simplicity and usefulness of aerobraking, but think the alternatives should be explored. How about using a really strong electrodynamic tether and electric engine? This would create power as it entered Earth's magnetic field, driving the rocket. You'd have a lot of electric <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

<[A mass ratio of] 2.7 is between 70-80% of the vehicle being fuel, right?><br /><br />63% propellant mass out of the total gross mass. A damned high mass penalty compared to a heatshield mass of less than 15%.<br /><br /><...Is there a generalized artchitecture that would allow this? Three planets for the price of one? ...putting up more robust spacecraft that can (with several fuellings) travel throughout the inner solar system and aerobrake anywhere and prop. brake otherwise? Critical to this would be plentiful fuel (ISRU) or new propulsion tech. /><br /><br />If your spacecraft effectively only had to make one way trips becaue of refuelling at the destination before returning, then your spacecraft could be sized for 1/4 of the normal propellant mass at Earth departure. If you could aerobrake instead of propulsive braking, then your spacecraft could be sized for 1/4 of the propellant mass at Earth departure. Combine the two factors and you only need 1/16 of the propellant. The 1,700 tonnes of propellant in LEO needed for an all chemical rocket, all propulsive, 6 man Mars mission goes down to 110 tonnes of propellant. <br /><br /><br />[For unmanned cargo though, propulsive braking would be logical for a slow electric-propulsion reusable orbital tug.] <br /><br /><Funny, that's where I'd consider a high-G aerobrake. /><br /><br />Let me elaborate.<br /><br />The reason why propulsive braking might be an acceptable choice with electric propulsion is because of the very much higher ISP of electric propulsion. You are much more likely to have a break even point compared to aerobraking. With the lower ISP of chemical or nuclear propulsion the mass cost in propellant is so huge aerobraking is the obviously better choice.<br /><br /><br /><Definitely have to agree on the simplicity and usefulness of aerobraking, but think the alternatives should be explored. How about using a really strong electrodynamic tether and electric engine? This would create power as it en

 

[nyarlathotep]

What you really need is an upsized sea dragon (to be able to launch a ~40m pusher plate) and project orion. 2g acceleration at 100000s isp gets you to mars real quick.<br /><br />You'll still need that electric tug to drag your vehicle out to L2, since I don't think too many would be happy with you lighting it in LEO.

 

[gunsandrockets]

<What you really need is an upsized sea dragon (to be able to launch a ~40m pusher plate) and project orion. 2g acceleration at 100000s isp gets you to mars real quick. ><br /><br />heh<br /><br />The proposed interplanetary Orions didn't have ISP's that high. You are probably thinking of one of the giant interstellar proposals.<br /><br />But in any case we don't need Sea Dragon squared or L2 launch to get an Orion drive ship flying. The Ares V will have slightly greater launch capability than the old Saturn V, which means we could launch the old 10 meter pusher plate Saturn-Orion! Yeah the ISP is less than 3,000 seconds but so what it's good enough.<br /><br /> http://www.astronautix.com/lvs/oriturnv.htm