What are your ultimate commercial rocket designs?

[Hyperion5]

Falcon 9 can not sustain an engine failure during second stage flight, which is more than 2/3 of the time to orbit.

Also, Soyus can not sustain an engine out as there is only one engine per booster

I guess I should have made my point clearer, as I didn't mean the Soyuz had an engine-out capability.  With regards to Spacex, obviously they're trying their best PR spin on the Falcon 9's design, as it in my opinion is not an "improved version" of the Saturn family's design architecture. 

But what about the broader point?  Is the extra complexity of multiple engines per stage worth it if that stage can tolerate an engine failure?  Whenever I think of engine-out capability, I always think of Johnathan Barr and Bernard Kutter's Atlas V Phase 2 report showing 3 of 4 engine capability would reduce upper stage failures to almost 1/16th that of a single-engine Centaur (page 5 of http://www.ulalaunch.com/site/docs/publications/EELVPhase2_2010.pdf). 

[Jim]

Look at the PR spin surrounding the Falcon-1

[Hyperion5]

Well, I'd like one that can significantly expand the launch market through price and capability.  Easily reusable, scalable, and cheapest fuel (methane).  Aviation is something like a 700 billion dollar industry.  I'd aim to capture 1% of that, and would want to be able to provide worthwhile destinations and adventures in space. 

Can fly 1,2,3, or 5 1st stage cores per launch.  5 would be shaped like 8o8
Fully reusable, always crossfeeds when more than 1 core. 
1st stage cores are at least 20 meters in diameter. 

I've been trying to square this circle for awhile now, but I still can't figure out how you're going to make 20 m diameter rockets easily reusable.  You point out the difficulty of doing this straight off. 

Ground handling and payload processing would be a considerable challenge at all stages. But not insurmountable. 

The End.

I totally understand the colonization market is what you're trying to fill, but how can a rocket this size be both "easily reusable" while giving the ground crews such huge issues in moving it around or payload integration?  I get that you could make it reusable.  I'm just questioning whether anything this size could be "easily reusable".  I mean, the first stage alone on one of these Zeus rockets is going to dwarf an entire Saturn V.  Now imagine you've landed that first stage and now you've got to get it back on a crawler using a movable crane (because there's a chance it'd destroy any fixed crane landing at the boost-back pad).  It sounds like a herculean endeavor, even for someone with big equipment experience. 

It would have optionality to fly with no upper stage (just a payload on parallel staging to orbit), or 1 or 2 upper stages, also an option depending on mission/goals.  Option for the 3rd stage to be hydrogen (or nuclear if I'm allowed to suggest it). 

Part of the reason for large diameter is for radial artificial gravity within the transit vehicles and stations.  If first stage core is 20 m diameter, the payload, packed might be 30 meters.  Station, Inflated, might be 50+ meters.   

Alright, well I've got no problem with the 1.5 staging option.  In fact, given the Angara A5P is supposed to be a 1.5 stage vehicle, I'd say this is even more feasible with methalox engines.  The real issue with vehicles of this size is their size and power.  There was something like a 4.5 mile exclusion zone around the Saturn V rockets launching Apollo missions for very good reasons (see N-1 explosions).  So while you may be able to convince NASA to launch at Cape Canaveral or the ESA to let you launch at Kourou, that'd probably only be the single-stick versions.  Anything bigger than that you'd probably get pushback from the local community.  Just consider for a moment that the 300 decibels of sound from the Saturn V lifting off would be enough to kill you at distances of up to around 800 feet. 

That means you need to find a relatively isolated but still sizable island somewhere to launch.  Midway Atoll comes to mind (once housed 2000 residents), as do the islands just off the eastern coast of Puerto Rico.  Btw, fun speculation, but if you were to launch a 5-core Zeus rocket from Puerto Rico, I would guess you should be able to see it from as far away as Trinidad & Tobago in the south and the Bahamas and southern Florida in the north.  It'd be the first pan-Caribbean viewing experience of an artificial object's launch.   

[go4mars]

I totally understand the colonization market is what you're trying to fill

I would ideally strive for a business model that I felt had a chance of paying for it's development assuming only the terrestrial hypersonic passenger travel market.  Again, if you could get 1% of the global airline business, that's over $7 billion revenue each year.  The Martian wannabe's like me would be gravy.  Part of the reason for concentrating on effective "first" stage capability is because most of the work done by this thing will be throwing large passenger compartments across the world.  Initially ballistic, then zero g for a while, then a high and fast cruise phase, then relatively low and subsonic for final approach.  These passenger compartments could take many different forms, but I suspect would have electric battery powered systems for extremely fast cruising at 80000 feet or so, and before you got over populated areas, you'd get lower and subsonic.  There would be rockets with relatively small tanks for terminal descent vertical landing (or maybe horizontal landing).           

But yes.  These would also enable meaningful space colonization and tourism programs. 

how can a rocket this size be both "easily reusable" while giving the ground crews such huge issues in moving it around or payload integration?

Methane plays a part (no coking, cheap, etc.), but there are plenty of ways it could be conceivably devised.  I like the idea of landing with long legs, or on submerged risers, within a deep pool of fresh water (height adjusted so that the nozzles don't get quenched on landing (takeoff submerged "sea-bee style" is fine)).  This is also where you would take off from.  Payload integration would be a challenge, and would need special/new approaches.  The most common payloads might need to be constructed nearby (or possibly on barges).  It is possible that the payloads would fly themselves to the top of the rocket in a refuellable "propulsively landing powered clamshell", which is topped off just before launch.  An alternative is to have a "rocket belt" position the payload (or upper stages) on the rocket, then detach itself and fly up and away.  Either of these would need either significant shielding on top of the lower stage, or more likely would have significant cosine losses (a la superdraco orientation) so that the rocket plumes don't torch the stage directly below. 

Consider for a moment that the 300 decibels of sound from the Saturn V lifting off would be enough to kill you at distances of up to around 800 feet.

I think you mean 220 decibels at the source(correct me if I'm wrong), and diminishing pretty fast.  The last shuttle launch I saw (215 decibels at source?) was from KSC visitor's center (6 miles apparently) and it was not loud.  I could hardly hear it over the noise of the crowd.  I read somewhere that at 6 miles it's down to 90 decibels (I suspect measured when the wind was supremely calm).     I know it's a logarithmic scale, with 12-gauge shotgun blasts at 165.  Have a look at this chart to get a better idea of how it diminishes with distance (exponentially).  I would suggest that you are overstating the concern, though yes, it would be a factor to examine.  I missed Saturn V, but intend to be as close as practicable when FH lights up.  Guys who saw shuttle and Saturn V (similar lift-off thrust) generally seem to prefer the "throatier sound" from kerolox combustion.  I wonder how methane compares.

http://www.makeitlouder.com/Decibel%20Level%20Chart.txt 


The key idea here is creating something so capable and cheap, that it very meaningfully expands the market.  This is clearly NOT for just serving the current market a little better. 

[Hyperion5]

I totally understand the colonization market is what you're trying to fill

I would ideally strive for a business model that I felt had a chance of paying for it's development assuming only the terrestrial hypersonic passenger travel market.  Again, if you could get 1% of the global airline business, that's over $7 billion revenue each year.  The Martian wannabe's like me would be gravy.  Part of the reason for concentrating on effective "first" stage capability is because most of the work done by this thing will be throwing large passenger compartments across the world.  Initially ballistic, then zero g for a while, then a high and fast cruise phase, then relatively low and subsonic for final approach.  These passenger compartments could take many different forms, but I suspect would have electric battery powered systems for extremely fast cruising at 80000 feet or so, and before you got over populated areas, you'd get lower and subsonic.  There would be rockets with relatively small tanks for terminal descent vertical landing (or maybe horizontal landing).           

But yes.  These would also enable meaningful space colonization and tourism programs. 

Alright, but where are you going to get all these pads built?  The exclusion zones on rockets the size are going to be at least five miles around the pad in all directions.  That and noise zoning ordinances will eliminate launching near most cities.  Of course if you're launching from NYC to Singapore you probably won't mind a few hours getting there, but at lesser distances this would be a factor versus something like a supersonic jet. 

how can a rocket this size be both "easily reusable" while giving the ground crews such huge issues in moving it around or payload integration?

Methane plays a part (no coking, cheap, etc.), but there are plenty of ways it could be conceivably devised.  I like the idea of landing with long legs, or on submerged risers, within a deep pool of fresh water (height adjusted so that the nozzles don't get quenched on landing (takeoff submerged "sea-bee style" is fine)).  This is also where you would take off from.  Payload integration would be a challenge, and would need special/new approaches.  The most common payloads might need to be constructed nearby (or possibly on barges).  It is possible that the payloads would fly themselves to the top of the rocket in a refuellable "propulsively landing powered clamshell", which is topped off just before launch.  An alternative is to have a "rocket belt" position the payload (or upper stages) on the rocket, then detach itself and fly up and away.  Either of these would need either significant shielding on top of the lower stage, or more likely would have significant cosine losses (a la superdraco orientation) so that the rocket plumes don't torch the stage directly below.

I'm not sure I'd recommend the clamshell trick.  That sounds like it'd introduce more risk into this than you'd want.  You'll probably want as little risk in payload integration as possible.  Have you considered using a giant airship like the envisioned Aeroscraft ML86X?   

Consider for a moment that the 300 decibels of sound from the Saturn V lifting off would be enough to kill you at distances of up to around 800 feet.

I think you mean 220 decibels at the source(correct me if I'm wrong), and diminishing pretty fast.  The last shuttle launch I saw (215 decibels at source?) was from KSC visitor's center (6 miles apparently) and it was not loud.  I could hardly hear it over the noise of the crowd.  I read somewhere that at 6 miles it's down to 90 decibels (I suspect measured when the wind was supremely calm).     I know it's a logarithmic scale, with 12-gauge shotgun blasts at 165.  Have a look at this chart to get a better idea of how it diminishes with distance (exponentially).  I would suggest that you are overstating the concern, though yes, it would be a factor to examine.  I missed Saturn V, but intend to be as close as practicable when FH lights up.  Guys who saw shuttle and Saturn V (similar lift-off thrust) generally seem to prefer the "throatier sound" from kerolox combustion.  I wonder how methane compares.

http://www.makeitlouder.com/Decibel%20Level%20Chart.txt 


The key idea here is creating something so capable and cheap, that it very meaningfully expands the market.  This is clearly NOT for just serving the current market a little better. 

I'd always wondered if I'd remembered that old source correctly.  Still those kinds of decibels and the thrust involved suggest you're going to have to build some supremely sturdy launchpads, particularly because a launch failure, even with engine-out reliability and good quality control, would probably only be a matter of time.  So how do you make sure your pads could survive such an explosion?  I expect you could save any crew with a launch abort system at least. 

You were wondering what methane sounded like, so I found a video of a small methalox engine firing:



Methane engines have without doubt some of the most beautiful exhaust flames out there, with enough carbon that it's much more visible than a hydrolox engine's exhaust but only enough so that the flame burns a beautiful blue. 

[Kaputnik]

A question which I think might fit into this thread.

If we look at rocket motors/stages currently produced, which type would give the best impulse per $?

I would assume that some already-available unit produced for perhaps a military application would fit the bill. Maybe a missile, RATO, etc.

Any suggestions?

[Hyperion5]

A question which I think might fit into this thread.

If we look at rocket motors/stages currently produced, which type would give the best impulse per $?

I would assume that some already-available unit produced for perhaps a military application would fit the bill. Maybe a missile, RATO, etc.

Any suggestions?

Well Ed Kyle keeps talking up the Trident II D5 missile, which has had 143 successes in a row now.  Surely one of the ballistic missiles currently in use by Russia, US, China or the other major powers fits the bill.  I believe he said you could get about a metric ton into orbit with the Trident.  If you could super-size that missile to match the Soyuz you might be on the right track for commercial payloads.  The insurance premiums would be tiny compared to launching on a Zenit or Proton. 

You mentioned impulse/$.  I'm assuming you mean specific impulse/$?  There's also impulse density/$, which might be more important.  That seemed to be the approach that Spacex took.  They didn't aim to smash records on Isp/$, but they did do phenomenal on thrust/$ and quite well on impulse density/$.  I wonder how well any of those correlates with the cost per kg to orbit. 

[Robotbeat]

Impulse is different from specific impulse. Impulse is thrust times time and has units of Newton-seconds.

Also, Trident missiles aren't exactly cheap.

[Hyperion5]

Impulse is different from specific impulse. Impulse is thrust times time and has units of Newton-seconds.

Also, Trident missiles aren't exactly cheap.

Alright, but would you have some suggestions for him instead of the Tridents then? 

[Kaputnik]

I'm assuming you mean specific impulse/$?

No, I meant impulse/$.
i.e. the total propulsive power from the stage, divided by cost.

My thinking is that, if there is some off-the-shelf unit (I'm expecting it to be a small solid, I would be very surprised if it wasn't) then that could form an important part of a commercial MCD vehicle.

[R7]

Always liked the Rocket Company design a lot. High KISS factor. (But I think they needlessly reduced it by adding pilot to first stage)

http://www.amazon.com/exec/obidos/ASIN/1563476967/qid=1119462002/sr=11-1/ref=sr_11_1#reader_1563476967

[Hyperion5]

Always liked the Rocket Company design a lot. High KISS factor. (But I think they needlessly reduced it by adding pilot to first stage)

http://www.amazon.com/exec/obidos/ASIN/1563476967/qid=1119462002/sr=11-1/ref=sr_11_1#reader_1563476967

KISS factor?  That's a new one to me.  What does that stand for?

[kch]

Always liked the Rocket Company design a lot. High KISS factor. (But I think they needlessly reduced it by adding pilot to first stage)

http://www.amazon.com/exec/obidos/ASIN/1563476967/qid=1119462002/sr=11-1/ref=sr_11_1#reader_1563476967

KISS factor?  That's a new one to me.  What does that stand for?

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

[Hyperion5]

Always liked the Rocket Company design a lot. High KISS factor. (But I think they needlessly reduced it by adding pilot to first stage)

http://www.amazon.com/exec/obidos/ASIN/1563476967/qid=1119462002/sr=11-1/ref=sr_11_1#reader_1563476967

KISS factor?  That's a new one to me.  What does that stand for?

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

Ah, so it's about the principle of keeping things simple.  I've been wondering if that principle can sometimes run into problems when faced by things solved by built-in redundancy (extra complexity).  For instance, the Falcon 9 has triple-redundant avionics.  Is this an instance where the complexity that comes with redundancy and the reliability it can bring trumps simplicity? 

Or take engine-out capability.  The EELVs are quite reliable, but they've also suffered the occasional upper stage engine hiccup that's led to problems.  I remember seeing a ULA study that they'd see better than an order of magnitude drop in failure rate on a 4-engine upper stage compared to the current Centaur stage on the Atlas.  Wouldn't that be a case of where more complexity and redundancy would bring about better reliability?  I know it'd be extra engine expense, but the economies of scale would improve considerably if an Atlas were using 4X the upper stage engines it did previously. 

[R7]

Ah, so it's about the principle of keeping things simple.  I've been wondering if that principle can sometimes run into problems when faced by things solved by built-in redundancy (extra complexity).

Not necessarily, they can compliment each other. Design a system with KISS in mind, that usually yields better reliability alone. Then add redundancy, even better.

KISS in the Rocket Company vehicle showed for instance in first stage, IIRC it was pressure fed.

[Robotbeat]

Ah, so it's about the principle of keeping things simple.  I've been wondering if that principle can sometimes run into problems when faced by things solved by built-in redundancy (extra complexity).

Not necessarily, they can compliment each other. Design a system with KISS in mind, that usually yields better reliability alone. Then add redundancy, even better.

KISS in the Rocket Company vehicle showed for instance in first stage, IIRC it was pressure fed.

I think pressure fed makes sense a lot of times, but developing a pump has a LOT of advantages and shouldn't be discounted.

[go4mars]

Alright, but where are you going to get all these pads built?  The exclusion zones on rockets the size are going to be at least five miles around the pad in all directions.

A lot of the world's great cities are near bodies of water.  That's one option.  Another is high-speed transport, whether train, hyperloop, etc., to somewhere feasible and relatively nearby.  My friend's gps showed 347 km/hour on the Eurostar at one point for example.  Calgary might use Nose Hill Park. 

I'm not sure I'd recommend the clamshell trick... You'll probably want as little risk in payload integration as possible.  Have you considered using a giant airship like the envisioned Aeroscraft ML86X?   

If a giant airship existed and was available, feasible, and easily affordable, then it could be a great option.  But if you are building a powered clamshell anyways for other operational reasons, including perhaps abort contingencies and complete system reusability, then I think it makes sense to use it for stacking.  As to risk, the system would be tested many times first, in various wind conditions, etc.  If grasshopper and dragon, the Masten stuff, and other guys can control accurately enough...    then why not?

you're going to have to build some supremely sturdy launchpads, particularly because a launch failure, even with engine-out reliability and good quality control, would probably only be a matter of time.  So how do you make sure your pads could survive such an explosion?  I expect you could save any crew with a launch abort system at least. 

If it is necessary, build longish legs, and innundate the area with perhaps a meter of fresh water for launch/landing operations.  Though it might not be necessary.  A merlin doesn't seem to cut into the concrete.  I'm not sure how much larger this could be extrapolated to.  In any case, I suspect it will be trickier to deal with this issue on Mars or the moon for very big rockets. 

[R7]

developing a pump has a LOT of advantages and shouldn't be discounted.

And the RComp design didn't, but followed the minimum cost design ideology that lower the stage less need to aim for maximum efficiency in mass/Isp etc. Upper stage used ...  . .. . . .. .. either stock RL-10s or assumed RL-60, can't remember which. Don't have the book, read the story online back in 2005 or so. Unfortunately it isn't anymore available from web archive.

First stage recovery was solved very simply. It just went up and down, provided only enough vertical speed for the second stage to have time to horizontally accelerate into orbit.

[Robotbeat]

Pop-up first stage booster is a good idea.

[go4mars]

Pop-up first stage booster is a good idea.

Totally.  I suspect that's especially true for destinations above LEO.