3 shuttle main tanks, side-by-side

Michael Bloxham · 2007-01-08 10:07:24

Forgive my limited knowlegde of rocketry, but I don't see any big showstoppers with this one. Let me know if there are, but if not, try to keep discussion on what would make this difficult, and what we could do about it.

Just to start it off, I can imagine three shuttle main tanks in a straight line of 3. The two outer tanks comprise the first stage, the middle tank the second stage, and the final stage which rests atop the middle tank can be whatever you like. All three tanks can be started and checked before liftoff. The two outer tanks will obviously burn faster than the middle tank but RS-68 engines could be used on all three tanks.

This is a pretty obvious idea, so forgive me if it's been discussed before.

GCNRevenger · 2007-01-08 11:27:58

The idea for such a rocket has been kicked around in the past, particularly by CalTech's plan.

The trouble with such an arrangement is the performance you get per dollar, which isn't very good. The thrust-to-weight ratio is largely responsible for this, that because it is so heavy compared to the thrust it will have to burn a great deal of extra fuel, badly impacting payload. Three 8.4m wide tanks also generate more drag, which can't be good either. And the fact such an arrangement would probably need 12-15 RS-68 class engines (at ~$30-40M a pop) as well as three ~$60-80M tanks in addition to an upper stage (EDS style), that adds up (up to ~$1Bn each just for hardware).

Assembly in the VAB might be tricky too, it was never intended to accommodate rockets that wide as far as I know.

Michael Bloxham · 2007-01-08 12:26:35

I understand it is better to have a good thrust-to-weight ratio on the first stage, but could you give me some numbers? I imagine the Energia may be similar to the rocket I propose (did CalTech give it a name?), although I don't recall whether the first stage of the Energia was hydrogen or kerosene fueled? Perhaps the fact that the first stage of this proposed rocket is much larger in proportion to the second stage is somehow detrimental to performance aswell?

Regardless, what I would really like to know is the potential payload to LEO.

SpaceNut · 2007-01-08 12:34:08

"Three 8.4m wide tanks also generate more drag," I could see this one as being fixed by shaping them to a wings edge to lower the amount of drag.

I also wonder about the tanks on the sides as not being as large length as the center one and having them drop off to improve the weight ratio. The tanks and engines could come back down as Kistler proposes for reuse if posible.

I agree with the need for a more powerful engine is in order to make it work.

Michael Bloxham · 2007-01-08 12:50:38

Shortening the tanks might work, but I wonder whether the system might start to look a little, well, offensive :oops: . Better do a good job of that wing/shroud thingy to make it look socially acceptable.

GCNRevenger · 2007-01-08 14:12:31

Well lets see, before "TheStick" design for Ares-I was settled upon, a host of other ideas were also considered. Among these was using a Shuttle main tank with three or four SSME engines instead, with no booster rockets. Being that CEV won't weigh more than 20-30MT, it can be surmised thats what a single core could probably do give or take. This is pretty reasonable compared to the Delta-IV as far as mass and thrust, as the Shuttle core weighs around three times what the 8.6MT payload of Delta-IV can carry.

So then comparing this to Delta-IV Heavy, the three-core version notionally similar to what you have in mind, carries almost exactly three times what the single-core version does. So, multiplying the 30MT single-8.4m core by three gives you 90MT payload. Lets say that the greater efficiency lent by the increased size and the upper stage make it 100MT even. While this is not bad, its certainly not worth $1Bn worth of rocket.

This is also bad compared to what you could get for just a little bit more: the Delta-IV Heavy especially suffers from the problem of a bad thrust-to-weight ratio. Also, the upper stage in the Delta-IV design has to do more work per-mass than Shuttle, which is really almost a single-stage rocket if you don't count the boosters. Anyway, but by adding a six-pack of dinky little strap-on GEM solid rockets and a higher thrust upper stage, the Delta-IV Heavy would be somewhere in the 30-35MT range. Multiply this by three, and you are talking 130-140MT or so if you just add small boosters and upgrade the upper stage to a pair of J-2X rockets.

Reuse ability isn't going to happen, the tanks are made light weight so they aren't going to withstand impact anyway. Kistler can get away with it since they burn Kerosene, making the fuel tanks much much smaller.

Energia is notionally more similar to the original Ares-V design, with an 8m wide tank and four SSME-type engines burning Hydrogen for the main core, and between four and eight medium-sized Kerosene boosters (each about half the punch as our SRB). The upper stage would be powered by a single modified SSME-type engine.

The aerodynamic section thing isn't going to happen either, it would be too heavy for the amount of drag that would be decreased.

Michael Bloxham · 2007-01-08 14:32:31

Whats the fundamental difference between an Energia or an all-hyrdogen Ares V and a 3-main tank booster?

Is it possible to convert the outer tanks to kerosene without too much redesign?

Michael Bloxham · 2007-01-08 14:38:48

Let it be clear: What I propose is clearly a 2-stage launch vehicle. The outer tanks should burn much faster and drop away just like the SRB's of the current shuttle stack. I assume the Delta IV heavy is the same (even though it doesn't appear to offer any performance advantage)?

GCNRevenger · 2007-01-08 14:39:34

The outer tanks are much too big for kerosene fuel, simply making them shorter would probably make them too short, the longer the tank the less heavy structure you need to make up for the boosters pulling the core stage from one side.

Kerosene doesn't have a whole lot better performance than large solid rockets like the 5-segment SRB, so you don't gain much versus the current NASA Ares-V design.

Michael Bloxham · 2007-01-08 15:17:42

Thats okay, outdoing the AresV is not whats needed. I fear these SRB's aren't going to help NASA's PR machine when they start launching lunar missions, with all the talk of massive amounts of toxic propellents being released into the air with every 'noble' launch.

It sounds to me like a 3-main tank, Kerosene/Hydrogen, 2 or 3 stage launch vehicle is at least do-able, with no really big show stoppers, other than the pointlessness of it all in the face of better alternatives I guess.

The wikipedia article on the Delta IV mentions 'propellant cross feed from strap on boosters to the common core' as one of the potential upgrades to the Delta IV system. I briefly thought of this as an alternative to trying to squeeze enough engines under one booster, but this doesn't seem enough to warrant its expense. What do they say?

They also mention up to 6 strap on booster cores are possible. I guess you could at least consider the possibility of the same configuration but with shuttle main tanks. Although honestly, I do struggle to imagine that such an unwieldly booster could only lift about 200 tonnes. Where are the newmars number crunchers?

Michael Bloxham · 2007-01-08 15:40:46

What does the added weight of the kerosene boosters entail?

Lets just use our imagination for a moment... If we needed to mount an asteroid protection mission, with todays equipment, how many main tanks (kerosene or hyrdogen) and SRB's could we strap together before the whole thing starts to... well I don't know what would happen. Is there a limit?

GCNRevenger · 2007-01-08 16:01:42

Not many, before you would simply have to disguard the designs altogether. Multiple launches of a smaller rocket would be employed.

If you really want a Kerosene booster, make an American version of Energia, using Atlas-V rockets as boosters perhaps. It wouldn't be much better than Ares-V is now though I bet.

SpaceNut · 2007-01-08 22:12:42

Just playing around with what is available and some numbers what could we make from an Atlas V and a Delta IV?

Tthe Atlas V launch vehicle system

based on the 3.8-m (12.5-ft) diameter Common Core Booster (CCB) powered by a single RD-180 engine.
Diameter: 3.81 m (12.49 ft). Span: 3.81 m (12.49 ft). Length: 32.46 m (106.49 ft).
Atlas CCB. Gross Mass: 306,914 kg (676,629 lb).
Thrust (vac): 4,151.998 kN (933,406 lbf). Isp: 338 sec. Burn time: 253 sec. Isp(sl): 311 sec.
Centaur V1. Gross Mass: 22,825 kg (50,320 lb).
Atlas V Payload in kg - Configuration x Orbit
Configuration LEO 28 deg LEO Polar Geosynch Transfer Geosynch
Atlas V 401 12,500 10,750 5,000 N/A

So just the core is able to push 35,325 kg during the Burn time: 253 sec. with the RD-180 engine

Delta IV Heavy

Common core Diameter: 5.10 m (16.70 ft). Span: 5.10 m (16.70 ft). Length: 40.80 m (133.80 ft).
Delta RS-68. Gross Mass: 226,400 kg (499,100 lb). Empty Mass: 26,760 kg (58,990 lb). Thrust (vac): 3,312.755 kN (744,737 lbf). Isp: 420 sec. Burn time: 249 sec. Isp(sl): 365 sec.
Delta 4H - 2. Gross Mass: 30,710 kg (67,700 lb). Empty Mass: 3,490 kg (7,690 lb). Thrust (vac): 110.050 kN (24,740 lbf). Isp: 462 sec. Burn time: 1,125 sec.
LEO 28 deg: Geosynchronous transfer:
25,800 kg (56,800 lb) 10,843 kg (23,904 lb)

So just the core is able to push 56,510 kg with Burn time: 249 sec with the RS-68 engine.

ftlwright · 2007-01-11 16:05:05

General rule of thumb is that you want to keep the payload-to-mass ratio the same for each stage. Atmospheric drag, dead weight, rocket/nozzle optimization all play a part here (this is also why most aerospace engineers are skeptical when looking at SSTO or delivery vehicle to orbit solutions).

While kerosene is significantly more adaptable to mision requirements, you won't get any real thrust-to-weight advantages over solid rocket boosters. The tech has become extremely mature and I don't think safety is much of an issue here (besides its static mission nature).

The hypothetical here is extremely difficult to answer without a better definition of the mission profile. How long do we have? Approximately how large of a astroid? Speed? If your just trying to go for "OMG, LMAO LOL!!!11eleventyONE!!!" type thrust, your best bet is to just go with a Sea Dragon design and hope for the best. Both the laws of physics and chemistry are working again you here and there just aren't any simple solutions.

Michael Bloxham · 2007-01-11 17:34:05

Imagining it now, with anything more than 7 boosters strapped together the whole thing will start to look like very flat, like a pancake. Once this happens I guess the aerodynamic drag of the whole system starts to go up real fast.

GCNRevenger · 2007-01-11 17:41:23

Yeah thats kind of much

How about this, standard 10m Ares-V core, 4X five-segment SRBs, plus two Delta-IV CBC cores between pairs of boosters? Upgrade the upper stage to 12m and use a pair of J-2X engines.

Dayton Kitchens · 2007-01-11 22:10:20

Yeah thats kind of much
How about this, standard 10m Ares-V core, 4X five-segment SRBs, plus two Delta-IV CBC cores between pairs of boosters? Upgrade the upper stage to 12m and use a pair of J-2X engines.

What would be the LEO capability of that?

Michael Bloxham · 2007-01-12 04:18:51

What do we know about Max-Q and maximum heating?

http://en.wikipedia.org/wiki/Max_Q

Would simply making a 4xSRB launch vehicle twice as heavy keep the same Max-Q as with a 2xSRB launch vehicle? I mean, that would be just like flying 2 shuttles side-by-side right?

So no show-stoppers there?

GCNRevenger · 2007-01-12 09:50:16

What do we know about Max-Q and maximum heating?
http://en.wikipedia.org/wiki/Max_Q
Would simply making a 4xSRB launch vehicle twice as heavy keep the same Max-Q as with a 2xSRB launch vehicle? I mean, that would be just like flying 2 shuttles side-by-side right?
So no show-stoppers there?

Something like that, but the increased dead weight of the SRBs and the lower efficiency of the RS-68 versus SSME, would hold the payload down to around 150MT with just extra SRBs.

Now maybe if you added the extra pair of SRBs, the two Delta-IV CBCs, and the upgraded 12m upper stage with two or three J-2X engines then we're probably talking about ~180 metric tonnes.

Michael Bloxham · 2007-01-12 23:26:41

You mean something like this?

cIclops · 2007-01-13 06:24:28

Now maybe if you added the extra pair of SRBs, the two Delta-IV CBCs, and the upgraded 12m upper stage with two or three J-2X engines then we're probably talking about ~180 metric tonnes.

LOL. The cost of all that hardware plus the retooling for a 12m stage and new pad construction would be enormous and for what, an extra 36% lift capacity. KISS. For a little more recurring cost and a tiny fraction of the risk and development cost (for docking), 2 x Ares Vs can deliver 263 mT to LEO.

Michael Bloxham · 2007-01-13 08:37:44

Hold on... If there's no problem adding 2 extra SRB's, so long as the main vehicle is twice as heavy, then why not just make the main tank twice as volumous?

I guess there are a lot of questions to be asked here.

Can we get a way with a little more Max-Q or max heating than the space shuttle? If so, perhaps only 1.5 times as volumous? We could achieve that by lengthening the tank by only 50%.

Ofcourse, you'll still need more engines.

How many engines can we fit under a 10m tank?

Might these revised RS-68's be more throttleable than the SSME's?

If we're going to the trouble of retooling for this new 10m diameter tank, than why not 11 or 12m? Why did NASA stop at 10?

Perhaps we're overlooking potential physical problems with 4 SRB's; like excessive vibration and heating?

I bet we could assemble a 4 SRB vehicle in the assembly building without too much difficulty. Transporting it might be a problem though. I don't know much about pad modifications.

cIclops · 2007-01-13 09:09:03

If we're going to the trouble of retooling for this new 10m diameter tank, than why not 11 or 12m? Why did NASA stop at 10?

Because AFAIK Michoud still has has the capacity to make 10m tanks using tooling setup during the Apollo era.

Michael Bloxham · 2007-01-13 10:22:36

One down, five to go.

Thanks for that cIclops. I bet I missed some real good discussion about that here at newmars. Do you know of any posts?

GCNRevenger · 2007-01-13 12:04:52

I think you are pushing your luck with six RS-68 engines under a 10m tank, maybe seven. Five is a much more comfortable fit.

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#1 2007-01-08 10:07:24

Re: 3 shuttle main tanks, side-by-side

#2 2007-01-08 11:27:58

Re: 3 shuttle main tanks, side-by-side

#3 2007-01-08 12:26:35

Re: 3 shuttle main tanks, side-by-side

#4 2007-01-08 12:34:08

Re: 3 shuttle main tanks, side-by-side

#5 2007-01-08 12:50:38

Re: 3 shuttle main tanks, side-by-side

#6 2007-01-08 14:12:31

Re: 3 shuttle main tanks, side-by-side

#7 2007-01-08 14:32:31

Re: 3 shuttle main tanks, side-by-side

#8 2007-01-08 14:38:48

Re: 3 shuttle main tanks, side-by-side

#9 2007-01-08 14:39:34

Re: 3 shuttle main tanks, side-by-side

#10 2007-01-08 15:17:42

Re: 3 shuttle main tanks, side-by-side

#11 2007-01-08 15:40:46

Re: 3 shuttle main tanks, side-by-side

#12 2007-01-08 16:01:42

Re: 3 shuttle main tanks, side-by-side

#13 2007-01-08 22:12:42

Re: 3 shuttle main tanks, side-by-side

#14 2007-01-11 16:05:05

Re: 3 shuttle main tanks, side-by-side

#15 2007-01-11 17:34:05

Re: 3 shuttle main tanks, side-by-side

#16 2007-01-11 17:41:23

Re: 3 shuttle main tanks, side-by-side

#17 2007-01-11 22:10:20

Re: 3 shuttle main tanks, side-by-side

#18 2007-01-12 04:18:51

Re: 3 shuttle main tanks, side-by-side

#19 2007-01-12 09:50:16

Re: 3 shuttle main tanks, side-by-side

#20 2007-01-12 23:26:41

Re: 3 shuttle main tanks, side-by-side

#21 2007-01-13 06:24:28

Re: 3 shuttle main tanks, side-by-side

#22 2007-01-13 08:37:44

Re: 3 shuttle main tanks, side-by-side

#23 2007-01-13 09:09:03

Re: 3 shuttle main tanks, side-by-side

#24 2007-01-13 10:22:36

Re: 3 shuttle main tanks, side-by-side

#25 2007-01-13 12:04:52

Re: 3 shuttle main tanks, side-by-side

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