Big Dumb Boosters- and why we're overthinking this whole rocketry business

[Northstar1989]

After reading up on the Sea Dragon concept of the late 1960's, I've come to the conclusion that we're over-thinking this whole rocketry business.

http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29

You see, the concept of Sea Dragon was simple- it's a LOT cheaper to build a large, heavy, powerful, sloppily-designed rocket that can lift the same payload to orbit with a lot greater inefficiency; than it is to build a carefully-engineered, narrow-tolerance rocket like most current US rocket designs. This concept is known, quite simply, as "the Big Dumb Booster principle".

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

So, why do we waste so much effort on ultra-engineered rocket designs, made out of fragile composites and high-tech alloys, when it would be a lot cheaper to slap something together out of corrugated steel and just launch the payload to orbit on THAT? It's not like we've been re-using any of our current rocket designs, anyways... The current US approach to rocketry strikes me a bit like building a Ferrari just so you can take it on one short drive off the edge of a cliff, when any old junker would do...

My best guess is that we're not ACTUALLY utilizing our current approach because it's cheaper or more effective (because it's not)- we're utilizing it because of lobbying (launch companies can charge more for high-performance designs) and because politicians want to generate more jobs in the space industry for political reasons...

Please discuss.

Regards,

Northstar

EDIT: See also the posts and links below on the Aquarius Rocket- a more modern cousin of the Sea Dragon proposed for initial launches in 2005/2006.

Edited July 11, 2014 by Northstar1989

[astropapi1]

So, why do we waste so much effort on ultra-engineered rocket designs, made out of fragile composites and high-tech alloys, when it would be a lot cheaper to slap something together out of corrugated steel and just launch the payload to orbit on THAT?

The guys who build the probes wouldn't want their multi-billion robot to be launched on a rocket that was just slapped together. They want a rocket that can put their payload on the correct trajectory with high reliability, no matter the cost.

This design could be used for "low-cost" stuff like some resupply missionsa to the ISS. Something that was proposed for the Aquarius rocket. And even then, the 1/3 success rate didn't convince anyone to actually fund the project.

Edited January 18, 2015 by astropapi1
Dem gramer mistakes doe

[AlexisBV]

I think the point is still valid. Just because it's "dumb", made of steel, doesn't mean it isn't reliable, precise, or gets the job done. My wife has a $200 hybrid bike made mostly of steel. I have a $600 "cheap" road bike. Sure, I spend less energy getting from A to B, but I get flats between 2-10 times per year, and the mechanisms need fine tuning at least once a year. My wife's bike had 2 flats in 9 years, and seen a bike shop about as often. Her bike has even been in an accident with another bike (not mine), and not a dent. The other bike's wheel was completely destroyed. If it were a "mission", the steel bike would be able to carry on. The fancy one, not so much.

The point is, you can still get the job done with something simpler. Manage your requirements. Avoid scope creep. In the case of rocketry, I'm guessing fuel isn't the main cost driver. If that's the case, than the question "why bother with efficiency" is certainly pertinent.

Edited June 26, 2014 by AlexisBV

[Kryten]

The idea simply doesn't work with the market for payloads as it is. Look at sea dragon-it might have had a low price per kilogram, but it would be completely unaffordable. Why? Not enough demand to even fill out a single launch. Even if there was (let's some some government decides to send up a massive space station with it), there would not be the regular business required to pay for maintenance of all the equipment, to pay off the cost of producing all of that equipment in the first place, for paying the launch crews, et.c. et.c.

[YNM]

After reading up on the Sea Dragon concept of the late 1960's, I've come to the conclusion that we're over-thinking this whole rocketry business.

http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29

You see, the concept of Sea Dragon was simple- it's a LOT cheaper to build a large, heavy, powerful, sloppily-designed rocket that can lift the same payload to orbit with a lot greater inefficiency; than it is to build a carefully-engineered, narrow-tolerance rocket like most current US rocket designs. This concept is known, quite simply, as "the Big Dumb Booster principle".

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

So, why do we waste so much effort on ultra-engineered rocket designs, made out of fragile composites and high-tech alloys, when it would be a lot cheaper to slap something together out of corrugated steel and just launch the payload to orbit on THAT? It's not like we've been re-using any of our current rocket designs, anyways... The current US approach to rocketry strikes me a bit like building a Ferrari just so oyu can take it on one short drive off the edge of a cliff, when any old junker would do...

Nah, now you (also) likely don't want to kill so many people right ? Make sure your vehicle is reliable, not just suddenly you see crews exploded every 2nd launch, or they need two rockets for one launch because the other one is (statistically) will fail. The guy that said Russian ones are BDB, that's an underestimation IMO... They (manned or manned testing ones) launch things automatically. Docks automatically. Return automatically... and that's from day one. Various comments for comparisons between Soviets and US vehicles, just scroll not far down. Safe to say, bar the unmanned ones, they prefer reliable vehicles for these things.

For probes, similar reason - you don't want to build two hardware for a single project that actually only needs one because statistically the other one would fail. Imagine if a school has just built a micro-satellite and then they heard that the launch failed... they might have no more budget to rebuild it.

Edited June 26, 2014 by YNM

[Skyler4856]

Also keep in mind why governments fund the vast majority of rockets, their capability to launch military equipment, and I doubt any country would like to see their state-of-the-art top secret spy satellite fall into "enemy hands"...

[Nibb31]

What you're missing is that expendable boosters are already optimized for cost. They are already designed to be cheap and expendable. You won't be able to get any cheaper without sacrificing reliability, and reducing reliability will only increase insurance costs, which would offset any reduction in cost.

[Duxwing]

Also keep in mind why governments fund the vast majority of rockets, their capability to launch military equipment, and I doubt any country would like to see their state-of-the-art top secret spy satellite fall into "enemy hands"...

A technical note: spy satellites falling into enemy territory would smash into the ground.

-Duxwing

[R0cketC0der]

A technical note: spy satellites falling into enemy territory would smash into the ground.

-Duxwing

Actually they would burn up way before that, unless the rocket fails pretty shortly after liftoff. If it would fail pretty shortly after liftoff, the debris wouldn't be crashing on enemy territory.

[Dkmdlb]

In the case of rocketry, I'm guessing fuel isn't the main cost driver.

Elon Musk says fuel cost accounts for 0.3% of the launch cost.

The idea simply doesn't work with the market for payloads as it is. Look at sea dragon-it might have had a low price per kilogram, but it would be completely unaffordable. Why? Not enough demand to even fill out a single launch.

The point is that the BDB concept can work for rockets of all sizes, not just the big'o boys.

[linkxsc]

Makes me kinda chuckle cause in a lot of cases, thats about how I see it in KSP. From the start of the game until the end (with mods like KSP interstellar which often needs fairly heavy lifters, and other difficulty/realism mods) I have about 5 designs.

Tier 1, A launcher for satellites and probes that can put ~10 tons into orbit every single time.

Tier 2, A scaled up "KSO" version because I play with remote tech and KSPI and use those to launch relay networks, or i can use one to easily push 25 tons to LKO.

3rd can do 50 tons to LKO, and often a bit more, usually has about 30% fuel left before staging into the payload. Lots of these end up floating in interstellar space, though I do make an effort to recover them from time to time. (Also great for solar power > microwave stations that will later be moved to low kerbin orbit)

4th can do over 100 to LKO, rarely used, total lagfest on my laptop (I3 with 4gb ram and an "intel integrated" gfx chipset)

5th usually can be described as "Strap 8 orange tanks on, with 6 mainsails, and the 2 spares fueling the final stage craft's engines, turn off the mainsails gimbal, and hope for the best" which often works out just fine as long as your load is balanced and you throw a few struts on. (FAR can both help and kill this method tho)

Usually the tier 2 launcher is my primary station refueling machine too (or a modified tier 1 for refueling off of kethane bases on the mun and such). Ofcourse I can easily get probes to eve or jool using the tier 3 aswell. Anything larger usually gets refueled in orbit before making its voyage, but in the grand scheme of things anything i do that requires more than 3 tier 3 launchers, is just me dicking around building stations or crazy capital ships. Anything even remotely legit (like a lot of the really REALLY basic, refueling stops) can be done with the t3 or lower.

As far as IRL. It does make me wonder sometime why there has never been a settling on ~10 rocket designs good for different weights (gonna guesstimate the GSO transfer percentage, with the space shuttle it was ~ 15% of its LKO payload mass, so I'll jstu go with that, it should be understandable though)

T1 = ~2.5t LEO, 750lb GTO

T2 = ~5t LEO, 1500lb GTO

T3 = ~10t LEO, 3000lb

T4 = ~20t (The space shuttle was about this size, lifting ~53,000lb/26t to LEO, or 8300lb/4t to GTO)

T5 = ~40t

T6 = ~60

T7 = ~80

T8 = 100

t9 = 130 Saturn 5 was around 130 tons IIRC, or ~50 tons to the moon

t10 = 160

Above that god only knows what we're building up there, I'm sure that by the t7-10 we'd probably be better off building it in orbit. Although one must remember, there have been plans to design rockets such that the upper stages are left in orbit to be used as things later. (I recall 1 plan to use the space shuttle fuel tanks as storage modules that could be attached to space stations with a bit of in orbit modification.)

Just my tidbit

[Duxwing]

Actually they would burn up way before that, unless the rocket fails pretty shortly after liftoff. If it would fail pretty shortly after liftoff, the debris wouldn't be crashing on enemy territory.

What if you're in East Germany?

-Duxwing

[Red Iron Crown]

Cheaper, lower reliability boosters only make sense for cheap payloads, of which there are very few now. Maybe in the future, if we need to send up dumb tanks of propellant or other cheap supplies in dumb containers.

[TheShadow1138]

What if you're in East Germany?

-Duxwing

It would depend on launch site, but I'd imagine that any nations that had launched spy satellites to spy on East Germany would have done so from the Western Hemisphere. Thus, I believe a failed launch would either crash in the Atlantic, or burn up before reaching East Germany. I'm not sure if NATO nations launched spy satellites from locations other than KSC, Vandenberg AFB, or Guiana Space Center.

[YNM]

A technical note: spy satellites falling into enemy territory would smash into the ground.

-Duxwing

... And causing littering fines.

Just a note, the HST is actually derived from spy satellite technologies, and it's length is half of the Skylab. I'm not sure how many parts of the skylab were returning, but safe to say, if a reconnaisance spy satellite the size of HST were to deorbit, there might be significant debris.

Also, just imagine how expensive it is, if you have to replace it because of low reliability launchers...

[DerpenWolf]

I think I get the concept, you build your rocket crudely so it has to be big and thus heavy, and due to the lack of precision it becomes far easier to mass produce them. They wouldn't nessicarly be unreliable ( if the part has problems add more steel) it would just be inefficient and made big to make up for the inefficiency! Is this concept correct?

[Streetwind]

As far as IRL. It does make me wonder sometime why there has never been a settling on ~10 rocket designs good for different weights (gonna guesstimate the GSO transfer percentage, with the space shuttle it was ~ 15% of its LKO payload mass, so I'll jstu go with that, it should be understandable though)

T1 = ~2.5t LEO, 750lb GTO

T2 = ~5t LEO, 1500lb GTO

T3 = ~10t LEO, 3000lb

T4 = ~20t (The space shuttle was about this size, lifting ~53,000lb/26t to LEO, or 8300lb/4t to GTO)

T5 = ~40t

T6 = ~60

T7 = ~80

T8 = 100

t9 = 130 Saturn 5 was around 130 tons IIRC, or ~50 tons to the moon

t10 = 160

Question one: who should "settle" on this? There is not a single country in the world, today or at any point in the past, that has more than 10 active launchers at any one time. Heck, I'd be surprised if there ever was an entire power bloc that had that many. Only nowadays we're coming close to that largely because of the rise of commercial launch providers, and they don't exactly have much room to downsize: SpaceX has one active launcher, Orbital Sciences has one active launcher, ULA has three active launchers in distinctly different size categories.

Question two: Why so many rockets? If you have a rocket capable of lifting 20 tons, you don't need one capable of lifting 10 tons, because you can just stuff two small rockets worth of payload into the bigger one. And if you have one capable of lifting 40 tons, you in turn don't need one capable of lifting 20 tons... Of course that's a theoretical argument, rockets usually have very good reasons for being the size they are. But the point is: you don't need to tailor launchers for your payload. It's done the other way around, payloads are designed to be no larger than the largest available launcher can handle. And payload bundling is a very real thing. Consider the Falcon 9: it lifts 13 tons to low Earth orbit, making it fairly small on your scale. And yet, the one that's currently standing on the pad for launch has six satellites onboard. And the previous ISS resupply mission carried not only the Dragon cargo spacecraft, but also another five cubesats as secondary payload. It's an everyday occurence in spaceflight nowadays; there's no need to develop and maintain a 2 ton launcher when you can simply bundle six of those payloads and launch them on one rocket.

[Nibb31]

Also I don't see why "big and dumb" would automatically be cheap. Your average container ship is big, dumb, and made of steel, and still costs more than a Falcon 9 launch.

[linkxsc]

Cheaper, lower reliability boosters only make sense for cheap payloads, of which there are very few now. Maybe in the future, if we need to send up dumb tanks of propellant or other cheap supplies in dumb containers.

Whoever said simple and cheap means less reliability. In some cases simpler stuff is more reliable because theres less stuff to go wrong with it

Question one: who should "settle" on this? There is not a single country in the world, today or at any point in the past, that has more than 10 active launchers at any one time. Heck, I'd be surprised if there ever was an entire power bloc that had that many. Only nowadays we're coming close to that largely because of the rise of commercial launch providers, and they don't exactly have much room to downsize: SpaceX has one active launcher, Orbital Sciences has one active launcher, ULA has three active launchers in distinctly different size categories.

We are talking about the future correct? And countrys have settled on standards for stuff before. But yeah as it is now, outside of the commercial market thats slowly cropping up (and likely to get much much bigger) government space programs have often had a limited number of lifters.

Question two: Why so many rockets? If you have a rocket capable of lifting 20 tons, you don't need one capable of lifting 10 tons, because you can just stuff two small rockets worth of payload into the bigger one. And if you have one capable of lifting 40 tons, you in turn don't need one capable of lifting 20 tons... Of course that's a theoretical argument, rockets usually have very good reasons for being the size they are. But the point is: you don't need to tailor launchers for your payload. It's done the other way around, payloads are designed to be no larger than the largest available launcher can handle. And payload bundling is a very real thing. Consider the Falcon 9: it lifts 13 tons to low Earth orbit, making it fairly small on your scale. And yet, the one that's currently standing on the pad for launch has six satellites onboard. And the previous ISS resupply mission carried not only the Dragon cargo spacecraft, but also another five cubesats as secondary payload. It's an everyday occurence in spaceflight nowadays; there's no need to develop and maintain a 2 ton launcher when you can simply bundle six of those payloads and launch them on one rocket.

Now, theres actually several statements in here so.

So many rockets because I was just throwing numbers out there, they could easily have them in 50 ton increments if they wanted.

and the 10 ton vs 20 ton argument makes me lol. Remember, you may be able to put 2 payloads into orbit at once with the larger rocket, but that would in turn require more engineering on the payload so they can correct orbit themselves. Your 20ton lifter might not be able to put 2 payloads on their projected orbits as reliably as 2 separate launches.

At the same time, the 2 ton launcher was again, just me throwing out numbers. But thats about the size to LKO that I use for most of my deep space probe replication projects (most recent, and ISEE3, but well, theres no halo orbits in this game).

[Duxwing]

It would depend on launch site, but I'd imagine that any nations that had launched spy satellites to spy on East Germany would have done so from the Western Hemisphere. Thus, I believe a failed launch would either crash in the Atlantic, or burn up before reaching East Germany. I'm not sure if NATO nations launched spy satellites from locations other than KSC, Vandenberg AFB, or Guiana Space Center.

And hence the absence of a security risk for launching a spy satellite via a BDB.

-Duxwing

[YNM]

It would depend on launch site, but I'd imagine that any nations that had launched spy satellites to spy on East Germany would have done so from the Western Hemisphere. Thus, I believe a failed launch would either crash in the Atlantic, or burn up before reaching East Germany. I'm not sure if NATO nations launched spy satellites from locations other than KSC, Vandenberg AFB, or Guiana Space Center.

And hence the absence of a security risk for launching a spy satellite via a BDB.

-Duxwing

Ehmm... Surely not on those orbits ? I mean, spy satellite crashing over some populated cities, on the launching country ? Yeah, not security risk, but what a shame it would be...

Also, you might want to consider what I say here :

A technical note: spy satellites falling into enemy territory would smash into the ground.

... And causing littering fines.

Just a note, the HST is actually derived from spy satellite technologies, and it's length is half of the Skylab. I'm not sure how many parts of the skylab were returning, but safe to say, if a reconnaisance spy satellite the size of HST were to deorbit, there might be significant debris.

Also, just imagine how expensive it is, if you have to replace it because of low reliability launchers...

Additionally, there are other satellites which are larger than HST :

[Duxwing]

Ehmm... Surely not on those orbits ? I mean, spy satellite crashing over some populated cities, on the launching country ? Yeah, not security risk, but what a shame it would be...

Oh, of course: I wasn't disputing that putting many tons of hardware on a shoddy booster is a terrible idea. I was just disproving that whoever realizes that terrible idea should not worry about one's enemy's getting said hardware should the booster fail.

Also, you might want to consider what I say here :

Additionally, there are other satellites which are larger than HST :

http://upload.wikimedia.org/wikipedia/commons/thumb/a/ad/U.S._RecSat_Big_Picture.jpg/640px-U.S._RecSat_Big_Picture.jpg

I agree with everything but the littering fines' significance: any well-funded war department should be able to pay them.

-Duxwing

[cantab]

Actually they would burn up way before that, unless the rocket fails pretty shortly after liftoff. If it would fail pretty shortly after liftoff, the debris wouldn't be crashing on enemy territory.

Space junk can survive re-entry and hit the ground, and even a smashed-to-hell spy satellite will still be pored over by whoever has it.

Back on topic, I think people are in error in interpreting the "Big Dumb Booster" as being unreliable. A well-designed BDB should be very reliable, by virtue of being a simple design that's not pushing the limits of engineering and that once worked out is more-or-less stuck with.

The drawback, I think, comes from the point of view of the desire for national progress. Because a BDB isn't pushing the limits of engineering, its development won't expand those limits much. Long-term, more sophisticated launchers may come to overtake the BDB for cost-effectiveness.

[SUJETO]

[...]

Interesting IDEA ,,, But is a actually a nightmare for designers because the cost of design and build a X rocket is not only the price that you need to pay for a certain mission. Public relations/security/environmental laws/space debris concern/falling stages/buildings-installations/transport/lobbing/publicity/exorbitant wages/political concerns/customers...

The SATURN V is a example of the wish of the designers to have a cheap rocket with "old" technology. A big good rocket can not be made for our days...

[Armchair Rocket Scientist]

Ehmm... Surely not on those orbits ? I mean, spy satellite crashing over some populated cities, on the launching country ? Yeah, not security risk, but what a shame it would be...

Fortunately, even going to polar orbits, countries don't let a rocket launch overfly populated areas.

Here's a ground track of a polar orbit launch from Guiana Space Center:

NASA never launches to polar orbits from KSC, because in either direction you'd be overflying populated areas. Instead, they launch from Vandenburg, like this:

Russia can't really avoid launching over land, but their trajectories seem to mostly go over Kazakhstan, Mongolia, and the Asian part of Russia, all of which are sparsely populated.