When do we get an official Direct 3.0 Thread?
Good suggestion Danny, I'll see about making an MPEG version.And no, the LOX tank is sized to precisely the same capacity as the current ET's Ogive tank.We do still have an option to increase the capacity of both the LOX and LH2 tanks by ~7-9% (in the same way as NLS was going to), but right now, mostly for simplicity sake, we have simply chosen not to mess around with altering the capacities. We can close all performance requirements comfortably without it.Ross.
Quote from: PaulL on 05/22/2009 06:09 pmQuote from: kraisee on 05/22/2009 03:35 amOne of the best 'alternative' mission profiles which we have been able to confirm so far is that of using the EDS to perform the LOI as well as the TLI.Because the lander doesn't have to perform the LOI, it results in a lander which is considerably smaller and lighter than the current CxP design. This solves almost all of the Altair's height/stability issues and might even allow the thing to fit inside an 8.4m PLF again too. At this size and mass the LSAM & CEV will *easily* fit on a J-130, thus improving both costs and safety for each mission. Also by having multiple engines on an RL-10-powered EDS you get high Isp and a great deal of engine-out capability for the LOI as well, which is nice.With this profile we're seeing about 10% extra payload mass to the Lunar surface as well -- and that's the real point.Ross.Ross, this looks like a very interesting configuration. Having a JUS able to handle both TLI and LOI burns would probably also allow you to do a "full" Apollo-8 mission to any low lunar circular orbit with only one rocket.PaulLOver on the Altair thread, Ross said that the LOI accounts for just over half the total descent stage mass for the LSAM. Interestingly, this makes it in the ballpark of an EELV upper stage. My idea, on hearing this, was to leave the EDS basically as-is, and split the LSAM into a three-stage vehicle- LOI, descent, ascent. An extra stage sounds like a bad idea but remember it would be an already flying stage, and if all goes to plan might be man-rated anyway as part of a LEO-servicing EELV.As always in rocketry, it's a case of balancing the efficiency of added stages against their added complexity and costs.
Quote from: kraisee on 05/22/2009 03:35 amOne of the best 'alternative' mission profiles which we have been able to confirm so far is that of using the EDS to perform the LOI as well as the TLI.Because the lander doesn't have to perform the LOI, it results in a lander which is considerably smaller and lighter than the current CxP design. This solves almost all of the Altair's height/stability issues and might even allow the thing to fit inside an 8.4m PLF again too. At this size and mass the LSAM & CEV will *easily* fit on a J-130, thus improving both costs and safety for each mission. Also by having multiple engines on an RL-10-powered EDS you get high Isp and a great deal of engine-out capability for the LOI as well, which is nice.With this profile we're seeing about 10% extra payload mass to the Lunar surface as well -- and that's the real point.Ross.Ross, this looks like a very interesting configuration. Having a JUS able to handle both TLI and LOI burns would probably also allow you to do a "full" Apollo-8 mission to any low lunar circular orbit with only one rocket.PaulL
One of the best 'alternative' mission profiles which we have been able to confirm so far is that of using the EDS to perform the LOI as well as the TLI.Because the lander doesn't have to perform the LOI, it results in a lander which is considerably smaller and lighter than the current CxP design. This solves almost all of the Altair's height/stability issues and might even allow the thing to fit inside an 8.4m PLF again too. At this size and mass the LSAM & CEV will *easily* fit on a J-130, thus improving both costs and safety for each mission. Also by having multiple engines on an RL-10-powered EDS you get high Isp and a great deal of engine-out capability for the LOI as well, which is nice.With this profile we're seeing about 10% extra payload mass to the Lunar surface as well -- and that's the real point.Ross.
I have just created a new DIRECT v3.0 thread here:http://forum.nasaspaceflight.com/index.php?topic=17295.0This thread will remain open for a while still, in case there is discussion about the older version of DIRECT, but most discussion should move over now, please.Ross.
Quote from: kraisee on 06/01/2009 03:49 pmI have just created a new DIRECT v3.0 thread here:http://forum.nasaspaceflight.com/index.php?topic=17295.0This thread will remain open for a while still, in case there is discussion about the older version of DIRECT, but most discussion should move over now, please.Ross.This older version may become the current one again if regen RS-68s are sanctioned .
One of the best 'alternative' mission profiles which we have been able to confirm so far is that of using the EDS to perform the LOI as well as the TLI.Because the lander doesn't have to perform the LOI, it results in a lander which is considerably smaller and lighter than the current CxP design. This solves almost all of the Altair's height/stability issues and might even allow the thing to fit inside an 8.4m PLF again too. At this size and mass the LSAM & CEV will *easily* fit on a J-130, thus improving both costs and safety for each mission. Also by having multiple engines on an RL-10-powered EDS you get high Isp and a great deal of engine-out capability for the LOI as well, which is nice.With this profile we're seeing about 10% extra payload mass to the Lunar surface as well -- and that's the real point.
