It would be like if a competitor to Six Flags opened up a theme park 3 states over in the middle of nowhere and expected you to go there because it's cheaper instead of the Six Flags that is down the road.
Sorry for asking, but what do you mean with ITSY?Thanks.
Quote from: First Mate Rummey on 08/09/2017 08:42 pmSorry for asking, but what do you mean with ITSY?Thanks.ITSy is the nickname we've given to the subscale ITS. It's not official at all.
That would also likely change the stage to also be a 5m diameter but the same length reducing impacts on towers and other items placement in the GSE in support of the US and payloads on top.
I'm pretty sure they'd do side entry like Shuttle or Delta Clipper.
Quote from: Robotbeat on 08/01/2017 11:00 pmI'm pretty sure they'd do side entry like Shuttle or Delta Clipper.Only if you make the structure a) Winged or b) Lower aspect ratio. "Upper stage reuse" has been known to be possible since the first Shuttle reflight if you're prepared to design a vehicle to do it. What has made it difficult is if you insist on doing it with a high aspect ratio US, which is what a conventional US is. You are aware that the Shuttle reentry angle (when it lost most of its velocity) was rather nearer to 70degrees to the horizontal than horizontal?Or the DC-X slightly nose down concept was inspired by the USAF's experience with warhead reentry?This idea has a couple of inescapable facts connected with it.1) Every unit of mass you put on the US comes off the payload. On boosters it's more like 13:1. So you can add a (comparatively) huge amount of hardware to do recovery while sacrificing a (comparatively) small amount of payload.2) You can make VTO LV's very light because they are very optimized to be strong in exactly 1 axis, just like a soda can I've stacked 10 fully filled (but unpressurized, which is important as pressurization really helps) vertically. Try stacking with the 9 fully loaded cans on the side of a closed can and see what happens. Make sure you do it in a bowl. It's going to get messy. We know that a layer of paint is enough to insulate a LOX tank through 1st stage recovery engine on, but I don't think that's going to hack it for a side entry (let along not exploding due to flash boiling), do you?So (assuming you've beefed up the whole tank structure to handle substantial side loads) how will you handle the heat, given you have to retain propellant for landing?Obvious options I can see are a)Minimal mass by putting TPS on the "windward" side of the tank. b)Even layer of TPS on the sides of the whole stage c)Thinner layer of TPS on whole stage and slow spin the stage on landing ("Rotisserie" mode as they called it for Apollo and Saturn EDS).All of these offer exciting opportunities to advance the science of control systems quite a lot, with the possible exception of b), Which is the simplest (and heaviest) option. Fortunately the US Army has done quite a lot of work on the guidance issues associated with pairs of spinning tanks in tandem during their development of binary nerve gas shells (and some on bombs), as the consequences of a stray shell were quite serious. Obviously the tanks are rather smaller (and faster spinning) but AFAIK the mathematics still applies wheather it be 50Kg or 5000Kg of fluid and 1 or 1000RPM. Simply insert appropriate operating conditions and fluid properties. But remember a)All require the interior structure and/or the tank pressures to be increased, since this is completely unnecessary for current expendable US practice and b) the "exchange rate" for US is 1:1. Every lb/Kg/banana of mass you add comes off the payload reserve (which is no longer the payload reserve, and you'd be misleading people if you called it that) or off the available payload to orbit. With the exception of tank pressurization gas (which could in principle be vented, if you could retain the propellant) every unit of mass that goes to orbit on the stage (except the payload) has to come back, and be decelerated in the final landing.
Quote from: Robotbeat on 08/01/2017 11:00 pmI'm pretty sure they'd do side entry like Shuttle or Delta Clipper.Only if you make the structure a) Winged or b) Lower aspect ratio. ...
Further, many LEO missions are volume limited.There is absolutely nothing that is preventing SpaceX from building a recoverable upper stage for LEO missions.
All zat is rekvired is the VILL to do so!
Why is your post full of frowny faces? They'll figure it out eventually. And in the meantime, we get explosions! Win, win! :D
Anyway, I'm sure the recovery-attempt upper stage will look all weird with funky aerosurfaces for Falcon Heavy's maiden launch. Like a bastardized ITS spaceship.Turn that frown upside down! :D
7% GTOW - wouldn't that make the legs as heavy as the entire rocket?...
Quote from: meekGee on 08/29/2017 08:52 am7% GTOW - wouldn't that make the legs as heavy as the entire rocket?...7% of LANDING weight, not takeoff weight. And mostly due to the large span required for stability. The upper stage is relatively short and fat.
Quote from: envy887 on 08/29/2017 04:48 pmQuote from: meekGee on 08/29/2017 08:52 am7% GTOW - wouldn't that make the legs as heavy as the entire rocket?...7% of LANDING weight, not takeoff weight. And mostly due to the large span required for stability. The upper stage is relatively short and fat.Thank you for reminding me. Note that the heuristic for HTO vehicles is 4% of landing weight, despite the fact the XB70 managed to do it for 2% as the Boeing page of XB70 shows.