Author Topic: "Direct" Alternative  (Read 95272 times)

Offline simcosmos

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RE: "Direct" Alternative
« Reply #20 on: 09/06/2006 12:33 pm »
Hello Mike

I guess than can answer and Ross will correct me as needed ;)

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mike robel - 6/9/2006  4:41 AM
Ross,

I guess I forgot:  3 or 4 SSMEs in the core stage?

3 SSME (and later modified - expendable - 3 SSME or other equivalent thrust / ISP engine configuration) for the basic Direct launcher variants (ET core with equivalent STS propellants quantity and, at each side,  4 segment SRB)

5 engines whenever it would be time to increase the ET propellants capacity, 5 segment SRB, etc in order to have something more like Ares V (but still with STS ET diameter).

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mike robel - 6/9/2006  4:41 AM

Why an ATV in your CEV/ATV launch diagram?  Why not just a cargo module that the CEV would deliver (or other self-contained space station module)?

I believe that the ATV in the picture is just an example, but one thing is more or less certain (for basic Direct CLV variants): the payload under the CEV would need at least some kind of RCS mini-module or even its own propulsion module (if a station module, it could be something like Russian ones) given that the CEV + payload would be injected into a sub-orbital trajectory (for safe disposal of the ET core, like in STS).

If the payload has some RCS capability, it would then be able to keep a given stable attitude and allow the CEV to dock with it and act as the payload's main propulsion. However, in order to avoid such delicate operation before the circularisation burn, perhaps it would be better if the payload had a powerful enough RCS module or even its own small expendable tug (at least capable of making it reach a stable low orbit) or if that payload and its tug were somehow connected to the CEV's SM bottom.

It is in times like this that a Biconic CEV (or capsule with hole in the heatshield) would be very handy, hehe but we can find solutions for the current CEV configuration + basic Direct + extra payload. Anyway: there are some options / talks about the topic being considered by Ross and me in our emails ;)

Meanwhile, I have uploaded a new image in my LivePics page (later to be moved to the flickr photo set) as well uploaded past development images in the flickr url. For the interested, just click in the thumbnail or in the links that are in my forum's signature.

Work in progress... The first Orbiter simulator implementation should happen *soon*: the flight tests should then provide a few nice images and, if having time, will perhaps also do a clumsy demo - read development - video (not 100% sure yet)

António
my pics @ flickr

Offline Norm Hartnett

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RE: "Direct" Alternative
« Reply #21 on: 09/06/2006 06:10 pm »
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kraisee - 5/9/2006  2:16 AM

Also posting this here.

Gads, that sure is a good looking vehicle. To bad NASA isn't going to develop it.

I don't think I ever saw a full costing on this. Are you doing one or did I miss it?
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline kraisee

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RE: "Direct" Alternative
« Reply #22 on: 09/06/2006 10:01 pm »
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mike robel - 5/9/2006  11:41 PM

Ross,

I guess I forgot:  3 or 4 SSMEs in the core stage?

Mike, António already replied, but I'll phrase it my own way too :)

The Phase 1 "Direct" Shuttle Derivative, would utilise 3 standard SSME's, and the exact same tank capacities used today.   It would basically do the same job as STS does right now, taking ~142mT of hardware up the hill on every flight.   The difference though, is the proportion of that mass which is useful payload.   The configuration change allows you to trade Orbiter mass for payload.   "Direct" launches 73.9mT of useful hardware to LEO instead of just 16mT using STS.

The intention is to replace the main engines with a cheaper alternative as soon as it can be developed.   Either 3 x RS-25e (no requirement for air-start, just chep production) or 2 x Hi-Isp (450s vac or better) RS-68 derivative can be utilised.   Rocketdyne/P&W would have to perform trades to confirm which is the best cost option to persue, and that's what we go for ultimately.


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Why an ATV in your CEV/ATV launch diagram?  Why not just a cargo module that the CEV would deliver (or other self-contained space station module)?

I used it as a demonstration of utilising the extra capacity of the Direct.   It's only really a suggestion, but it does offer a number of advantages:   ATV is almost ready to fly right now and it requires no additional development money to be spent at all.   It neatly fits inside the SLA, and would be more than capable enough to provide cargo delivery at the same time as CEV flights.   Other options are possible, but they all require development $$$.


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I like the idea, it seems to have minimum change.  Agree with Jim that its a little overkill in terms of capacity for the CEV only, but we could orbit some whomping big cargo modules in additon to crew rotations, as well as have high capacity boosters for future projects.

Exactly.

Ares-I can't offer any other capabilities other than CEV launches.   It isn't capable of doing anything else.

Direct can open up a lot of options which Ares-I can't, and saves a lot of time & money in the process.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline kraisee

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RE: "Direct" Alternative
« Reply #23 on: 09/06/2006 10:07 pm »
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Norm Hartnett - 6/9/2006  1:57 PM

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kraisee - 5/9/2006  2:16 AM

Also posting this here.

Gads, that sure is a good looking vehicle. To bad NASA isn't going to develop it.

I'm putting together a proposal.   NASA has not done much yet on the Ares progrm which isn't helpful to Direct too.   It would not actually take a radical course correction to go this path.   With the right argument (saving $8Bn development and $2Bn per year operational), I think it could gather support.


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I don't think I ever saw a full costing on this. Are you doing one or did I miss it?

Dang, sorry Norm.   I posted one on another thread, but forgot to include it here.   Let me amend that...

Ross.
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Offline rsp1202

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RE: "Direct" Alternative
« Reply #24 on: 09/07/2006 12:34 am »
I agree; the crew launcher (Ares 1B?) has changed from a sow's ear into a silk purse. (Though I don't know why LM added the little button nose to the LES/boost protective cover.) Now, suggest a clever way of docking the CEV/LSAM to the EDS on the cargo hauler (Ares 1C?), and I'm sold. I also must have missed something: you're saving the Ares V for Mars?

Offline Norm Hartnett

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Re: "Direct" Alternative
« Reply #25 on: 09/07/2006 12:50 am »
You dock the CEV to the LSAM. Your pilot gets into the LSAM and docks it to the EDS using some nifty adapters on the landing pads of the LSAM. Seems simple and "Direct" to me. :)

Thanks Ross you did publish some graphs in this thread on page 1.
I was looking for something more like a spreadsheet with a bit more detail.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline rsp1202

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Re: "Direct" Alternative
« Reply #26 on: 09/07/2006 02:22 pm »
Okay, at least it's a concept. Thanks.

But it's not that simple if you have to take time to move crew into the LSAM, power up its systems, and fly backwards with a big honkin' package stuck to your nose while making delicate docking maneuvers. Adapter also adds a degree of mechanical complexity, but whether that's marginal or not, I don't know. Then what; power everything down in the LSAM for coast phase, then power up again reaching Moon orbit? Mission timeline is effected, too; how long do you want to linger in Earth orbit doing things before TLI. There's also the change of philosophy, not using the CEV to control major maneuvers.

The two-launch Direct method is elegant in many ways, and perhaps these things by themselves are not that big a deal. I'm easy to convince, NASA maybe not so much.

Offline Norm Hartnett

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Re: "Direct" Alternative
« Reply #27 on: 09/07/2006 04:33 pm »
Yeah that was a simplistic answer and I'm no Rocket Scientist but I'll babble anyway.

Actually I would be more concerned about getting the CEV and LSAM mated than about getting them docked to the EDS. If the CEV initial orbit criteria are as they are now you would have a very limited amount of time to get mated and have the SM (presumably much bigger) get your short stack into a safe orbit or alternatively if your initial orbit criteria was defined by a need to safely dispose of the ET you would still have a limited mating time. A failure to launch the EDS would leave you the unpleasant choice of dumping the LSAM into the atmosphere.
Assuming all that happened you wouldn't be looking at "fly backwards with a big honkin' package stuck to your nose while making delicate docking maneuvers" Remember the LSAM is designed to land on it's feet. A better way of putting it would be "landing with a big honkin' package stuck to the top of your head while making delicate docking maneuvers" basically the LSAM is designed to fly that direction.
If NASA can have a truss screw itself...
to the ISS then I am sure there are any number of options for getting a hard dock to the EDS. Since at least one design for the LSAM has large solar arrays, power might not be an issue plus the Direct design may have enough margin for a fairly large SM able to supply consumables for both modules. All this is just me gassing of course.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline rsp1202

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Re: "Direct" Alternative
« Reply #28 on: 09/07/2006 04:48 pm »
No, good show. The devil's in the details, and this little one is critical to Direct operations. There are bound to be more. I was concerned about control laws for handling the stack, line of sight issues for the pilots, increased workloads, power consumption -- a whole bunch of conditions spiraling out from this one operation.

I'd like to see these things fly, but not if it's used as a political/cost excuse for cancelling Ares V down the road.

Offline Norm Hartnett

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Re: "Direct" Alternative
« Reply #29 on: 09/07/2006 05:03 pm »
Another thing that just popped into my mind. The Apollo capsule docking to the LEM/TLI stack (or the CEV docking to the LSAM/EDS) was a small mass bumping into a big mass. With Direct you have two dockings. A small mass bumping into a slightly bigger mass and then two more almost equal masses bumping into each other. Elastic collisions with near equal masses do not lend themselves to hard docks.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline HailColumbia

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Re: "Direct" Alternative
« Reply #30 on: 09/07/2006 05:36 pm »
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Norm Hartnett - 7/9/2006  12:20 PM

If the CEV initial orbit criteria are as they are now you would have a very limited amount of time to get mated and have the SM (presumably much bigger) get your short stack into a safe orbit


What about using the LSAM to perform the burn to a safe orbit while still in the adapter? You would have to redesign the adapter probably, but, as its an imaginary adapter anyway, thats not a big deal.  (and of course you would lose precious decent propellent)
-Steve

Offline yinzer

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Re: "Direct" Alternative
« Reply #31 on: 09/07/2006 06:12 pm »
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Norm Hartnett - 7/9/2006  9:50 AM

Another thing that just popped into my mind. The Apollo capsule docking to the LEM/TLI stack (or the CEV docking to the LSAM/EDS) was a small mass bumping into a big mass. With Direct you have two dockings. A small mass bumping into a slightly bigger mass and then two more almost equal masses bumping into each other. Elastic collisions with near equal masses do not lend themselves to hard docks.

Sure they do.  The ISS is rapidly approaching the weight of the Shuttle Orbiter, and they dock just fine.
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Offline yinzer

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Re: "Direct" Alternative
« Reply #32 on: 09/07/2006 06:26 pm »
And yeah, this is one of the problems with using the "Direct" launcher to carry large amounts of cargo to ISS.  Shuttle uses the OMS engines to do a two-burn ascent to LEO.  This requires less delta-V overall, and when one is carrying along a lot of non-payload weight, that's important.  Also, when the upper stage weighs 30-70 tons, you need to be much more careful about where it lands, which suborbital injection helps with.

But you need an engine restart to make it work and RCS for the between-burn coast period.  If you're using SSME for the ascent, that means you need separate circularization engines.  Not an insoluble problem, but if your launch vehicle is cheaper because you ditch all the Orbiter costs, except for the aft fuselage, and except for the GPCs, and except for the OMS/RCS pods... you can see where this leads.
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Offline Norm Hartnett

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Re: "Direct" Alternative
« Reply #33 on: 09/07/2006 06:41 pm »
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yinzer - 7/9/2006  12:59 PM

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Norm Hartnett - 7/9/2006  9:50 AM

Another thing that just popped into my mind. The Apollo capsule docking to the LEM/TLI stack (or the CEV docking to the LSAM/EDS) was a small mass bumping into a big mass. With Direct you have two dockings. A small mass bumping into a slightly bigger mass and then two more almost equal masses bumping into each other. Elastic collisions with near equal masses do not lend themselves to hard docks.

Sure they do.  The ISS is rapidly approaching the weight of the Shuttle Orbiter, and they dock just fine.

Oh good needn't worry about that then.
“You can’t take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware.” Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline kraisee

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Re: "Direct" Alternative
« Reply #34 on: 09/07/2006 08:27 pm »
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HailColumbia - 7/9/2006  1:23 PM

What about using the LSAM to perform the burn to a safe orbit while still in the adapter? You would have to redesign the adapter probably, but, as its an imaginary adapter anyway, thats not a big deal.  (and of course you would lose precious decent propellent)

Hail, that is *precisely* the mode I have been assuming, and which sim is going to model in Orbiter for this.

And I'm toying with an idea of "topping-off" the LSAM's Decent tanks with LOX from the EDS after docking.   It's not necessary I don't think, but offers one growth option which would increase performance in the future.

As it is though, Direct can place about 13mT extra in LEO (IMLEO) at the start of the mission compared to the Ares-I and V together, so this is not necessary.

Ross.
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Offline kraisee

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RE: "Direct" Alternative
« Reply #35 on: 09/07/2006 08:48 pm »
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rsp1202 - 6/9/2006  8:21 PM

I agree; the crew launcher (Ares 1B?) has changed from a sow's ear into a silk purse. (Though I don't know why LM added the little button nose to the LES/boost protective cover.) Now, suggest a clever way of docking the CEV/LSAM to the EDS on the cargo hauler (Ares 1C?), and I'm sold. I also must have missed something: you're saving the Ares V for Mars?

Rsp,
My approach to this extra docking maneuver would be to keep the crew aboard the CEV - so they are permanently in their lifeboat, just in case.   Control the docking to the EDS from there IMHO.

There will be full suite of cameras and landing radar on the LSAM for Lunar approach anyway, so these can be used for this docking operation.   The crew won't be able to see the EDS during this approach because it will be obscured by the descent stage anyway, so it must be done by camera and instruments.   Further, the LSAM is being designed to perform completely autonomous Lunar landings, so the systems will already be set-up to be remote-controlled anyhow.   This should thus not impact the mass allocation of the LSAM in any way.

Here's a rudimentary drawing showing the basic approach...

I have a design for a simple mechanical release system (not pyro) which "lets go" of the entire cradle holding the LSAM in the SLA through it's launch.   The SLA separates from the core, with the LSAM still inside, and the CEV remaining on top.   LSAM then performs the circ. burn and the remaining section of SLA are then discarded.   The CEV then transitions and docks.   This approach has the benefit of fully testing the LSAM's engines and knowing they work even before the TLI occurs.

As I just mentioned, after docking with the EDS, the LSAM's descent stage tanks could be topped off by the EDS if additional performance is required, but the "Direct" approach already launches a larger LSAM and more propellant than Ares does, so this isn't actually needed.


Ares-V actually becomes unnecessary for Mars.   It sure would be nice, but if it's cancelled, the first launch vehicle you built, the CLV, is still capable enough still launch Mars missions in just five 90mT launches, placing 450mT in LEO!   Four launches of Ares-V also place about 450mT in LEO, but you still need to launch the crew on a fifth launch - so there is no real benefit to that approach.

*IF* the money still exists in 12 years time to grow the "Direct" into a really big launcher, you can easily make the original 27ft diameter ESAS CaLV design, which gives the same performance as Ares-V.  But the CaLV is taken out of the critical path, and even if it gets cancelled we can still go explore.   With just Ares-I, if Ares-V is cancelled we ain't going nowhere at all.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline kraisee

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RE: "Direct" Alternative
« Reply #36 on: 09/07/2006 08:53 pm »
And Norm,
I'm continuing to develop the finite details of the cost structure.

I've got this updated comparison which includes the EDS costs in the totals for both Ares and Direct approaches.

I think you'll all agree this is quite an eye-opener.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline yinzer

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Re: "Direct" Alternative
« Reply #37 on: 09/07/2006 09:49 pm »
The ESAS report claimed that a 4-seg RSRB w/ 3xSSME core stage would require 3 launches to do the lunar mission - this is the vehicle that you are suggesting.  How do you enable the two-launch solution?

And if a 70-ish ton launch vehicle can do a two-launch solution, why not use the Atlas Phase 2, which can Lockheed says can lift 73 tons in a 3-body configuration while still being able to carry the CEV to ISS in a single-stick configuration, and being much more useful to the commercial and military launch markets by bringing economies of scale to Atlas production?

Round and round we go, I suppose.
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Offline kraisee

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Re: "Direct" Alternative
« Reply #38 on: 09/07/2006 10:30 pm »
Yinzer - yes, the ESAS did exactly that.   But it did not factor in any EDS.

With the use of the EDS during the latter part of the ascent phase, like Ares-V does, you boost NET performance by 15mT and you get the 19mT of EDS in orbit in addition.   Two launches places 183mT in LEO at the start of the mission, which is 13mT more than Ares-I and Ares-V will launch together.

That firmly places this solution into the 2-launch category.

And I'm sorry, while "1.5 launch" sounds less, it isn't.   Count the number of launch vehciles they use...   Unless my math teacher "learned me bad"; 1 plus 1 still equals 2, not 1.5...

And frankly, running two launch vehicle operations instead of just one will cost a LOT more, not less.

And yes, Atlas Phase 2-Heavy (3 core) could also do this.   If NASA could get around the political crap-shoot which would follow all those job losses.   I could easily support that solution if the politico's could.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline rsp1202

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Re: "Direct" Alternative
« Reply #39 on: 09/07/2006 10:55 pm »
Re: Phase 2. It's also risky to trust future viability of offshore supply lines. Producing RD-180's here in the States should be emphasized, unless RS-84 development is pushed.

And Ross, I agree the CEV should control docking; using IFR and auto systems is mandatory, especially if the LSAM turns out to be one of the horizontal-design concepts rather than vertical as envisioned in ESAS.

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