tag:blogger.com,1999:blog-7598615455712402973.post2320568910772916535..comments2024-03-25T11:14:45.840-04:00Comments on Polymath: On the lasting importance of the SpaceX accomplishment, Page 3: towards European human spaceflight.Robert Clarkhttp://www.blogger.com/profile/16114043697010364282noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-7598615455712402973.post-72771411912957413092013-11-26T00:45:15.771-05:002013-11-26T00:45:15.771-05:00 I agree. The Italians the other big player in ESA... I agree. The Italians the other big player in ESA also favor the solid-fueled version of the Ariane 6 because a large part of the solid-fueled Vega is built in Italy. Choosing the solid-fueled Ariane 6 helps to subsidize the Vega too.<br /> However, ironically if SpaceX succeeds in reusability then even also the solid-fueled Vega will become obsolete, because of the drastic drop in launch costs.<br /> So even this justification requires you believe SpaceX will fail in reusability.<br /><br /> Bob ClarkRobert Clarkhttps://www.blogger.com/profile/16114043697010364282noreply@blogger.comtag:blogger.com,1999:blog-7598615455712402973.post-29121574937823701382013-11-25T12:40:19.532-05:002013-11-25T12:40:19.532-05:00The boosters on P7C are stretched versions of the ...The boosters on P7C are stretched versions of the Vega first stage; they would actually be the cheapest to develop. One of the biggest arguments in favor of the P7C design is that the new solids could be used to upgrade Vega as well, and that fixed costs and development costs would be shared over two programs. Ariane 6 would also consist of only three major components, made on three production lines, one shared with Vega; the H2C design would have required five, and P1B six unique production lines with no synergies with Vega whatsoever. However, human spaceflight potential remains a strong advantage of H2C, but as sad as I find it as a European, there is very little interest in human spaceflight from European nations, in particular France.<br /><br />I will write something about Ariane 6, since I find it very interesting and I would love to expand on the "winners and losers" of the competition. However, I've been very busy over the past few weeks with other stuff on my blog, so that will take some time. Marijn Molemanhttps://www.blogger.com/profile/10374646748718489690noreply@blogger.comtag:blogger.com,1999:blog-7598615455712402973.post-75394258564211345792013-11-24T03:18:00.731-05:002013-11-24T03:18:00.731-05:00 Thanks for that info. When I wrote this, I was co... Thanks for that info. When I wrote this, I was comparing to the solid rocket versions being discussed then. These ALSO used small strap ons to increase the payload to GTO. In fact the two Vulcain solution had greater payload both with and without strap ons than the solid rocket versions:<br /><br />http://exoscientist.blogspot.com/2013/03/the-coming-sstos-multi-vulcain-ariane.html<br /><br /> The latest version of the solid rocket version of the Ariane 6 uses larger rocket motors, so does not need the strap ons to reach the 6.5 mT to GTO. However, the development cost of these new large solids will be very expensive. A high development cost contributes to a high flight cost because this development cost has to be paid off by the price of the launcher. <br /> Actually, the cost of the small solid strap ons is known and is actually comparatively small because such already exist and have been used effectively for both the Delta IV and Atlas V for years now to increase their payload to orbit. In fact the liquid fueled version of the Ariane 6 with the strap ons would be comparable in price to those of the Delta IV and Atlas V since it would be similar to them.<br /> However, the two Vulcain solution would have the advantage that it could also be used to give Europe its own independent manned spaceflight capability.<br /> I agree with what you said about the three Vulcain solution. It would be even more capable then the two Vulcain and could also give Europe a manned spaceflight capability. I was focused on the two Vulcain because it would be so low cost without the strap ons, and could be so rapidly developed to give Europe manned spaceflight.<br /><br /> Bob ClarkRobert Clarkhttps://www.blogger.com/profile/16114043697010364282noreply@blogger.comtag:blogger.com,1999:blog-7598615455712402973.post-8319863610845555392013-11-23T13:48:58.660-05:002013-11-23T13:48:58.660-05:00" Also, I've been informed by people who ..." Also, I've been informed by people who aware of CNES studies on a multi-Vulcain Ariane that the estimated price for the two-Vulcain Ariane 5 core would be only 50 million euros, about $60 million(!) So for only a ca. $200 million development cost and a $60 million launch cost the ESA could have manned spaceflight ability."<br /><br />You should be aware of something though; this variant, using 2x Vulcain and known as H2C, can only get a payload of 2200 kg to GTO, which translates to about 4500 kg to LEO. However, in order to reach the GTO payload of 6.5 tons that was targeted by CNES, it needed to use 4 solid strap-on boosters. The exact cost of these boosters are not known, but they are very expensive, usually about 10-20 million dollars for a booster. The 6.5 ton version of the H2C was estimated by the European Air and Space Academy to cost €98 million, which is about $138 million. <br /><br />However, the option of a 3x Vulcain core was investigated too, though never officially by ESA. Because it did not need strap-ons to reach the 6.5 ton mandate, it was a far lower cost option than the H2C design. It would still have trouble reaching the €70 million mandate, but was theoretically closer to that mandate than either H2C or Multi-P. <br /><br />The biggest problem ESA has with low-cost launchers is the geo-return principle. Every country investing in a program roughly gets the same amount of money back in contracts. That's why Ariane and Vega are such mosaics of hardware from different countries, and it's why non of the current Ariane 6 designs can reach the 70 million euro goal assuming current industry standards. However, they are looking at being less strict about it with Ariane 6, and Dordain has recently said that he is confident that the €70 million goal can be reached.Marijn Molemanhttps://www.blogger.com/profile/10374646748718489690noreply@blogger.comtag:blogger.com,1999:blog-7598615455712402973.post-69586194900926277042013-05-20T15:35:07.363-04:002013-05-20T15:35:07.363-04:00Hi Bob:
I pretty much agree with, except that so...Hi Bob:<br /><br />I pretty much agree with, except that solids could be handled like buying a giant cheap JATO. <br /><br />You don't worry about the solid, let its maker worry about refills. You just bolt it on, and send the empties back to him. <br /><br />It's like the old glass bottle sodas. You get a rebate on the empties if you can recover them (and you can). Otherwise, they're pretty cheap even without the rebate. That's the appropriate idea. <br /><br />If thrust vector on the solid is not an issue (admittedly a big "if" unless you design specifically for that), then the solid can actually be quite cheap (as JATO was). That's how you implement the appropriate idea.<br /><br />Then it's "gas-and-bolt-on and go". Like with JATO. Could be quite routine, just like JATO once was.<br /><br />GW<br /><br />Gary Johnsonhttps://www.blogger.com/profile/06723964751681093047noreply@blogger.comtag:blogger.com,1999:blog-7598615455712402973.post-59462154827053983352013-05-19T20:27:42.354-04:002013-05-19T20:27:42.354-04:00Thanks for the always informative response. Howeve... Thanks for the always informative response. However, I do have an over arching agenda. And that is to make a manned launcher and a reusable ("gas and go") launcher. That is not possible with solids. But that is the only way spaceflight will become routine.<br /><br /> Bob ClarkRobert Clarkhttps://www.blogger.com/profile/16114043697010364282noreply@blogger.comtag:blogger.com,1999:blog-7598615455712402973.post-42521369996836567912013-05-18T17:27:01.449-04:002013-05-18T17:27:01.449-04:00"All-solid" 1st stage I'm not so sur..."All-solid" 1st stage I'm not so sure about, but the presence of solids early in the trajectory is actually a good thing, despite the obsolescence of the technology. <br /><br />There's no reason not to use a very old technology, if it confers a benefit. To think otherwise is nothing but an age bias. That can be quite harmful, and in a variety of ways and venues, not just launch. <br /><br />Between launch and about 80 kft/M2-2.5 conditions (typical of vertical launch), Isp is relatively unimportant to launch outcome. Engineering studies have always shown this.<br /><br />Thrust per unit frontal area is very important in that flight phase, and solids have an inherent advantage over all known liquids in those terms, and for a variety of very good engineering reasons. Those same studies showed this, too.<br /><br />The only-possible superior non-nuclear, non-airbreathing, technology might be hybrids, if those can be scaled to 120+ inch sizes. No one yet has scaled them up that big, in flying form, even experimentally. <br /><br />And, all the potential airbreathers are far shorter on thrust per unit frontal area than the liquid rockets, again for a variety of good engineering reasons. This includes scramjet, ramjet, and any possible turbine-related technology. <br /><br />That does not rule out the parallel-burn rocket-airbreather, however. Not any more than it rules out the parallel-burn solid-liquid, or the parallel-burn hybrid-liquid. Those two (solids and hybrids as strap-on boosters shed early) are both good solutions to improving effective launched mass fraction per unit launch cost.<br /><br />If you want an airbreather in the no-more-than M2-ish range, I'd suggest (plain) ramjet as the one with the lightest hardware weight per unit frontal area, by far, over anything with turbines in it, no matter how "advanced". <br /><br />For max M2 only, no more than a simple pitot (normal shock) inlet is required, and you can use a convergent-only nozzle and light the thing subsonically. Isp potential is about half to two-thirds that of a "supersonic" design. Thrust at lower speeds is way far better. Such strap-ons would be easily recoverable and re-usable. <br /><br />Note that I said nothing about scramjet. Scramjet is completely inappropriate if you clear the usable atmosphere at only M2. Scramjets typically won't even work at all until you are well above M3.5 to 4. <br /><br />If you depress the trajectory to stay lower in the atmosphere in order to make the scramjet useful, you waste all your airbreather Isp advantage in the extra drag incurred at lower altitudes. <br /><br />There is no way around that, which is really why the X-30 project died. Most of us working in airbreathers knew that, long before the X-30 project ever started. <br /><br />In short, I see no niche for scramjet in space launch, only in missile propulsion for the M4 to 10 range. <br /><br />GW<br /><br />Gary Johnsonhttps://www.blogger.com/profile/06723964751681093047noreply@blogger.com