New details on CEV

[najab]

><i>I've suggested to use the SM engine to slow the bell-CEV speed on earth return...</i><p>A stupid suggestion if ever I've heard one. Even a three year-old can see the flaw in this 'plan'.</p>

 

[gaetanomarano]

<br />why?<br /><br />I hope that future vehicles will be not made to (ONLY) burn in atmosphere!<br /><br />CEV is a little object (great part of moon-hardware is already lost or burned when it come back to earth) but, when we will have a giant vehicle like the mars-ferry, we will burn it in atmosphere and save only the "cone"?<br /><br />where is the flaw?<br /><br />spacecrafts use (and will use) their engines to enter or exit form planets and satellites orbit<br /><br />they only need the propellent to do it (enter in earth orbit or simply slow its speed)<br />

 

[najab]

Let's see if you can figure this out - what is the SM engine going to burn?

 

[tomnackid]

"they only need the propellent to do it (enter in earth orbit or simply slow its speed) "<br />-------------------------------------------------------<br />And if pigs "only" had wings they could fly. Don't you EVER get tired of looking like a fool???

 

[tomnackid]

Sorry, I'm pulling a "G-man" here and answering my own post. <br /><br />Anyway, G, your proper response should have been something like:<br /><br />"Well, could someone please tell me how much delta V is required to slow the CEV down from escape velocity to orbital velocity and how much propellant will that translate into? Oh, and if its not too much trouble how will the mass of the required propellant compare to the mass of a heat shield that do a direct reentry?"<br /><br />By doing this you will be a constructive member of the Space.com community and not a blithering idiot. See, its not so hard.

 

[gaetanomarano]

<br />my true impression is that ESAS is NOT a good-made-plan but a GOD-made-plan... no one can critic this DIVINE PLAN... not even in its minute details...

 

[najab]

<blockquote><font class="small">In reply to:</font><hr /><p>my true impression is that ESAS is NOT a good-made-plan but a GOD-made-plan... <p><hr /></p></p></blockquote>This isn't about ESAS, it's about the CEV slowing down on it's way back from the Moon. And you haven't answered my very simple question: what is the SM engine going to burn to slow down?

 

[tomnackid]

my true impression is that ESAS is NOT a good-made-plan but a GOD-made-plan... no one can critic this DIVINE PLAN... not even in its minute details... <br />-----------------------------------------------<br />When I want a blithering idiot to critique my country's space program I will give you a call. In the meantime many well informed, well educated people on this board and in other places HAVE critiqued the plan. Some critiques I agree with some I don't, but either way it doesn't really matter. Not being an engineer or astronaut I have no say in what the spaceship should look like, what it should be made out of, what it should run on. As am American taxpayer my responsibility is to let my elected officials know how I want my money spent. IF the only choice at the moment is between a space plane that is very very expensive to operate yet only uses a tiny fraction of its capabilities and exploration of the moon and mars in a more modest vehicle then I support the latter. And by exploration I don't mean dumping a bunch of souped up RC race cars on the moons surface and hoping that somehow they will run across interesting stuff. Especially considering the fact that rovers that can operate autonomously over long ranges for long periods of time and actually make important discoveries and can be mass produced for a reasonable price are probably further away than a working CEV!

 

[gaetanomarano]

<br />I'm not an engineer... some peoples may design a mission or a vehicle and engineers build them<br /><br />but I can give a response in "tons" from a past calc I've made here for LSAM+shenzhou...<br /><br />from 2.5 tons to escape lunar orbit (with no brake on return to earth) ...the CEV weight (without the propellant/weight used to exit the lunar orbit) ...earth gravity six times the moon... I think around 24 tons to enter earth orbit and 8-10 tons only to brake to earth orbital velocity... but (only this time...) I can be wrong... after all I'm not an engineer...

 

[najab]

Okay, let's assume your figures are right (no they are not, but let's assume they are) - that's another 8-10 tons that has to be boosted out of lunar orbit, so how much additional prop will be required for TEI, which means how much more prop required for LOI, and how much more will be required for TLI, and how much more massive will the launch vehicle have to be?<br /><br />The answer: that (mere) 8-10 tons will increase the liftoff mass by at least 20 additional tons.

 

[tap_sa]

<font color="yellow">" that (mere) 8-10 tons will increase the liftoff mass by at least 20 additional tons. "</font><br /><br />Huh? A <i>lot</i> more, if we are talking about liftoff mass from Earth. 120-150t at least. We are talking about 13-14km/s of deltav for that 8-10t payload. In GT's world we'd be filling up at L-1 Exxon <img src="/images/icons/wink.gif" />

 

[najab]

Yup, I just realised I was misunderestimating it. <img src="/images/icons/wink.gif" />

 

[josh_simonson]

The CEV section is rather long winded about re-entry stuff, but it looks to me like they are doing a 'skip' re-entry so that the CEV can adjust it's course to always land accurately in the landing zone. <br /><br />A direct-only re-entry would either require waiting up to a couple weeks for a landing window for the landing zone or water landing somewhere in an ocean (as Apollo did).<br /><br />There was a blurb that it's only recently been discovered (90s) how to skip in a capsule with a L/D ratio less than 0.5 (CEV is 0.3) so there may be some risk that it doesn't work out, forcing a fallback to a short direct landing window with water landing as a backup.<br /><br />Still, in order to do sharp course correction during the 'skip' entry, the CEV needs large sidewall angles so that it can bank without burning it's sides. So the difference between the bi-conic capsule and the CEV is that they both probably skip in, but the CEV can do so accurately.

 

[mattblack]

It's all about re-entry from Lunar etc speeds. Good luck slowing a lifting body of spaceplane coming back to Earth at 25000 mph (39000 kmh)!! Or, designing a thermal protection system to do so. The Apollo shape is obviously proven, as is the Soyuz/Zond.<br /><br />Also, Apollo CM had a lift over drag ratio of 0.5 and Gemini had 0.15. I don't know what Soyuz's is, but I'd bet it was (about) halfway between Gemini and Apollo. Also, the CEV CM has that added 'bulge' in it's shape which I would think is related to adjusting its C.G. to something more favourable? <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[JonClarke]

"So the difference between the bi-conic capsule and the CEV is that they both probably skip in, but the CEV can do so accurately."<br /><br />We need to be careful with terminology here. Bottom firsdt and nose first biconics are different beasts. Nose first bionics are highly manouverable (originally developed for MIRV warheads). I can't comment on the properties of bottom first biocnics.<br /><br />I would not call the Soyuz a biconic in any shape or form. But it has both successful returned from the Moon (despite what was said earlier) and carry out skip entries.<br /><br />Jon<br /><br /> <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>

 

[josh_simonson]

Thanks, I'll use 'bell shaped' in the future.

 

[vt_hokie]

<i>did they ever decide who is going to build the CEV? I understand it is between Lockheed Martin and Boeing/Northrop Grumman?</i><br /><br />Does it even matter? NASA basically dictated the uninspired capsule design, shooting down any more innovative proposals? So, no matter who builds it, it's just going to be a revised Apollo capsule.

 

[mattblack]

(Rhetorical) Excuse me but WHAT more innovative proposals?! <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[tomnackid]

"Does it even matter? NASA basically dictated the uninspired capsule design, shooting down any more innovative proposals? So, no matter who builds it, it's just going to be a revised Apollo capsule."<br />----------------------------------------------------------------<br /><br />Yeah, lets just chuck the billions of dollars we spent developing and actually flight testing the Apollo technology so you armchair rocketeers can jerk off over something with fins and racing stripes.

 

[Robert_D]

One thing I haven't seen mentioned is the fact that the CEV will be facing backwards during TLI. Does anyone know if that is mentioned in the report (I have only read the executive summary so far). Does anyone know what the g force will be during TLI?<br /><br />Thanks.

 

[mattblack]

In Gemini when the Agena was lit "eyeballs out" it was about 1g. The Apollo SIVB/Apollo stack experienced about 1g "eyeballs in". So I guess the EDS/LSAM/CEV stack would be something similar, though eyeballs out. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[frodo1008]

Correct! In order to use the SM to slow from 25,000 mph to 18,000 mph takes extra propellents!! Propellents that have to be taken all the way to the moon and then back before they can even be used to slow the capsule! That is a LOT of extra weight! So much so in fact that any adventage in the bell shape is totally overcome by this factor alone!!<br /><br />Another BAD IDEA brought to you by that great professor of bad ideas otherwise known to all as gaetanomarano!<br /><br />Doesn't the professor realize that people who have truly vast experience have already designed the vehicle?<br /><br />Also just as he feels perfectly free to critisize such people because as he says the vehicle dosen't exist yet. He evidently will not give the same consideration to these experienced people that he gives himself here!!<br /><br /><br />At any rate a smaller version of this design has already proven itself in going to the moon with men in it, and then bringing them back safely! I realize this as I actually worked at Rocketdyne at the time and helped to build and inspect and even test almost every type of engine in that project! The project was called Apollo!!!<br /><br />Why should NASA attempt another unproven design, when they already have one that worked so very well!!!!

 

[mlorrey]

"Yeah, lets just chuck the billions of dollars we spent developing and actually flight testing the Apollo technology so you armchair rocketeers can jerk off over something with fins and racing stripes. "<br /><br />Except that NASA also spent billions actually flight testing lifting body designs, more than a half dozen different ones in the 60's and 70's, and billions more in the 80's, 90's, and 00's. The X-37 is based on the X-24A, and is the most aerodynamically studied aircraft body, far more than the Apollo's skipping ability.<br /><br />The Apollo capsule design is based on the phallic jerk-off spasms of the corporate-welfare-dependent ICBM industry and shallow politicians looking to divert public opinion with fireworks shows that build no actual infrastructure in space, or reusable space launch infrastructure on earth.

 

[rubicondsrv]

mlorrey <br /><br />a capsule is the most effecient way to build a RV in terms of mass to volume with the exception of a sphere which is impractical for many reasons one of wich is that a sphere only supports balistic reentry. <br /><br />for LEO other options such as winged, biconics, and lifting bodies may be better suited to some tasks. <br />however for higher reentry speeds such as from the moon they become impractical. they also do not have as many viable abort options (try doing a reentry with a winged veichle without constant controll input)<br /><br />also capsules cost less to design, build, and operate than other options. (RLVs and winged veichles require high flight rates to become the economical option.)<br /><br />This is not to say that winged vheicals and lifting bodies do not have a place but it is not trips to the moon or staying on orbit at a space station for six months at a time.<br /> <div class="Discussion_UserSignature"> </div>

 

[tomnackid]

Also an Apollo derived capsule has the option of doing skip reentry for a more accurate landing within the continental US. It can also, in an emergency, do a direct reentry (something a Soyuz derived capsule can't do from the moon) and land anywhere there is relatively flat terrain--land or sea (something a lifting body or winged vehicle can't do). <br /><br />I have no doubt taht we will have winged runway landing spacecraft someday when the traffic to and from LEO warants it. NASA has done more than its share of the ground work in this regard. The technology is there, it is up to industry to take the ball and run with it (which it hasn't yet). In the mean time I don't want to see NASA's mandate to explore space hog tied until some "perfect" spacecraft is invented. Columbus didn't ned steamships to cross the atlantic--I'm sure he would have found them very comfortable and convenient, but he wasn't going to wait around for that. similraly you don't need a spaceplane, space hotel, space refueling depot to start exploring the mon. Those things will be nice when the come--and they will come--but I'm not going to make NASA wait around for them. NASA is in the business of (a) technologica research--which as mlorrey pointed out they have already doned loads of whn it comes to spaceplanes and lifting bodies, and (b) exploration--which has been somewhat neglected in the shuttle era. They are not in business to run taxis!