I noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?Forgive me if this is a non-issue, as I am not too good with the rocket science side of these things.
Quote from: gladiator1332 on 06/01/2009 05:23 pmI noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?Non-Issue.. Far less offset than current shuttle stack.. Plenty of gimbal range for SSME's to keep Jupiter tracking as required. Small payload penalty for offest thrust.
I noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?
I hope that the new pdf will have some good, large dimensioned drawings of each version of 3.0 for us modelmakers. I have watched the after skirt/thrust structure of the core change quite a bit over the span of time.
Quote from: kraisee on 06/01/2009 04:13 pmThe Fwd Skirt actually comes in along with the 'foam' which covers the rest of the LOX tank. Its just a visual thing. They could be separated, but we wanted to keep the video short.Ross.Do you still need the foam now that the orbiter is gone? How much does the foam weigh? I would think the SRBs can take the impact of shedding ice. How about the Delta IV Heavy? Does it shed a bunch of ice on itself on ascent? I have seen some video of Saturn V launches and huge chucks of ice are coming off.Danny Deger
The Fwd Skirt actually comes in along with the 'foam' which covers the rest of the LOX tank. Its just a visual thing. They could be separated, but we wanted to keep the video short.Ross.
Quote from: kraisee on 06/01/2009 04:13 pmThe Fwd Skirt actually comes in along with the 'foam' which covers the rest of the LOX tank. Its just a visual thing. They could be separated, but we wanted to keep the video short.Ross.Thanks, I knew I'd catch your attention ! But this is confusing... "comes in along with the 'foam' " ? What exactly comes in along ?
Jupiter's forward skirt is build of what ?
TIA again, (hope I'm not abusing your patience).
Do you still need the foam now that the orbiter is gone?
How much does the foam weigh?
I would think the SRBs can take the impact of shedding ice.
How about the Delta IV Heavy? Does it shed a bunch of ice on itself on ascent? I have seen some video of Saturn V launches and huge chucks of ice are coming off.
Copied from V2.0 thread, since it appears to be just as relevant to DIRECT 3.0...Quote from: kraisee on 06/01/2009 03:05 pmAnd 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.Not heard of that 7-9% stretch option before.I'd suspect this is because the relationship of SRB-to-ET-to-Shuttle results in more space under the ET for engines than DIRECT actually needs?Shrink the engine space and extend the H2 tank downwards?
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.
It recently occured to me to wonder how there is space under the "ET" to fit a bunch of engines at all. Shuttle's ET is sized to fit between the SRB's (and presumably not to extend too far down into the base heating zone). Nothing about the shuttle "demands" that this should leave enough space under the ET for a set of engines.
That also raised another question. DIRECT's H2 tank height (bottom of barrel section to thrust beam) is defined by the distance between the lower & upper SRB attach points.
Adding another segment to the SRB also requires the same H2 barrel stretch. I'd always assumed this was a 25% increase in core fuel, but now that doesn't seem right.How much does the core fuel load increase for the heavy config?
Quote from: TrueBlueWitt on 06/01/2009 05:29 pmQuote from: gladiator1332 on 06/01/2009 05:23 pmI noticed that the Jupiter-130 will have two engines closer to the front of the vehicle, and one closer to the back. Will this create an offset thrust situation or an offset weight situation? And if so how will this be counteracted?Non-Issue.. Far less offset than current shuttle stack.. Plenty of gimbal range for SSME's to keep Jupiter tracking as required. Small payload penalty for offest thrust.Sure, but does it affect failure modes? I can imagine that a loss of one of the two paired engines would still allow a controllable stack for AOA or ATO (depending on timing), but if you lose that single engine, with all thrust now off-axis, do you have to shut everything down and fire the CES? (ps - very nice graphics!)
Ross... any further word on dropping vectoring control on SRB nozzles?
And what is it going to carry other than garbage? If it can't come down like the shuttle, then it is useless for science or return hardware. Access and loads are bad.
Quote from: TrueBlueWitt on 06/01/2009 05:29 pmRoss... any further word on dropping vectoring control on SRB nozzles?It seems to be a viable option which would reduce the per-flight costs by a reasonable amount and which would also improve both LOM and LOC too.Its an option which really needs further detailed trade study after the Jupiter's have been selected though. We aren't going to pursue it at this time, mostly because we don't have sufficient resources to do it comprehensively and because we have other priorities with the Augustine commission just around the corner.Ross.
...Speaking of which.. Ross... any further word on dropping vectoring control on SRB nozzles?
Quote from: TrueBlueWitt on 06/01/2009 05:29 pm...Speaking of which.. Ross... any further word on dropping vectoring control on SRB nozzles?Hey ! Fixed nozzle SRBs were considered by MSFC as of last year (to my knowledge) in the context of Ares V. Now, compare the [roll] control authority of 6 RS-68 @ 10m v. 3 SSME @ 8.4m (roughly; and even with the 4seg to 5 or 5.5 seg difference). Eh ? Let's give Caesar what is Caesar's.
Ross, Looking at the detailed pictures of D3, it looks like you (team) are dropping the current ESM panel attachment method for LSC or frangible joints up at the Orion/SM. If you change the panel attachment method (6 connections, 2 per panel), that will change the load path into the Orion drastically. And not having anything under the SM puts the SM in tension instead of compression like it is in Ares I. Changing the load path into the Orion/SM carries a time & money penalty for redesigning them. Is this something you have considered either via schedule & cost or via panel/faring redesign? I thought I remember it being stated that the most recent Orion version would be "held" and adapted to Direct.
Would an ATV fit inside the Shroud? Could lift one basically "for free" if the case. let it do it's own docking.