Ariane 6: solid vs. liquid

[spacediver]

It is now a few weeks that ESA pointed the way to the future of European space transportation during their ministerial conference in Italy. Besides the development of the new Ariane 5 ME upper stage a clear decision towards an Ariane 6 development was made.

In the aftermath of the conference voices of ESA officials could be heard that a decision towards an all solid Ariane 6 (except for the cryogenic upper stage) is already made. If this is true I see a dark future coming for European space transportation.

During the last months I was working on an ESA study for new launch service concepts, including detailed cost estimates for different launcher solutions. For me the most interesting result is that an all cryogenic launcher, using 3 Vulcain 3 engines (optimized for sea level operation) in the first and one Vinci in the second stage and no additional boosters leads to similar cost as all the solid launcher versions that we investigated. The reference mission for all concepts was defined with 6500 kg to a GTO trajectory.

The cost argument is the one mostly heard when the solid vs. liquid discussion is going on, because, as we all know, a solid stage is less costly than a liquid stage. But the truth is that solid launch vehicles always need at least one stage more to reach GTO than the liquid launchers and therefore, on the systems level, lead to about the same systems cost. 

In case of the next European launcher we have to take into account higher development cost for a solid compared to an all cryogenic launcher, much higher development risks for the large (in some concepts segmented) CFRP solid motor casings, the higher dynamic loads for the upper stage and payload and, for me the most important argument, the loss of the large liquid engine technology in Europe!

Once the solid Ariane 6 is in service and the Ariane 5 decommissioned, the ability to build large cryogenic engines in the 100t thrust class will be vanished within a few years. What ever launcher comes after Ariane 6 cannot build on this crucial technology anymore! It is unlikely that anyone in Europe is willing to spend >5 billion Euros to redevelop such an engine again.

To me the case is clear: A solid Ariane 6 is a dead end! The next European launcher should be an all cryogenic, two stage concept without strap-on-boosters.

What do you think?

Spacediver

[IRobot]

Are you sure the Ariane 5 will be decommissioned?? I was under the impression that they complement each other, being Ariane 6 the cheap option with less flexibility.

[Nicolas PILLET]

Are you sure the Ariane 5 will be decommissioned?? I was under the impression that they complement each other, being Ariane 6 the cheap option with less flexibility.

Yes, AR6 is the replacement for AR5.

[woods170]

Are you sure the Ariane 5 will be decommissioned?? I was under the impression that they complement each other, being Ariane 6 the cheap option with less flexibility.

Yes, AR6 is the replacement for AR5.

Much like what happened to Ariane 4 and Ariane 5 it is a fact that AR5 and AR6 will co-exist for a number of years before AR5 is decommissioned.
However, calling AR6 the replacement of AR5 is somewhat besides the thruth. AR6 is the "thing next in line" but with substantially less lift capacity.
AR6 is therefore to be considered as the system to fit a re-defined ESA launcher strategy. Put shortly: AR5 is overpowered and even in dual-launch capacity is not economical. The answer, according to the French, is a smaller, more flexible launcher; AR6.
And for some funny reason the French are now pushing for a solid solution. However, it is NOT a done deal that AR6 will be all solid. The upper stage is very likely going to be cryogenic stage to be developed for Ariane-5 ME.

[rklaehn]

Ariane 6 going all solid means that europe is no longer even trying to compete for the GTO market.

They just want a launcher that is not prohibitively expensive at a low flight rate for institutional and military payloads, and that allows the french to subsidize the solid rocket motor industrial base that they need for ICBMs.

Really a shame given the leading position arianespace has right now for GTO payloads.

[spectre9]

People want to know why solids are hated.

This is why.

Goverments insist on them even though they're crap technology compared to kerolox.

The Russians and SpaceX are the only rocket scientists with brains still operating.

Sorry for the tone of this post but if ESA wants to build a solid Ariane 6 I believe that's absolute stupidity.

People don't build steam trains. Why? There's better.

It's the same with solid rocket fuel.

[woods170]

Ariane 6 going all solid means that europe is no longer even trying to compete for the GTO market.

They just want a launcher that is not prohibitively expensive at a low flight rate for institutional and military payloads, and that allows the french to subsidize the solid rocket motor industrial base that they need for ICBMs.

Really a shame given the leading position arianespace has right now for GTO payloads.

You should remember that Ariane began life as a launcher to assure European independent access to space.
In this case "independent access" was meant for institutional and military payloads.
The fact that Ariane now is the leading launcher in the commercial market is actually a side-effect. Ariane has always been expensive, actually too expensive to justify it's existence for the relatively low number of institutional and military payloads that fly on it.
Therefore, the launcher was offered to launch commercial payloads. That secondary role soon overtook the primary role in absolute number of launches.
But, the consideration for Ariane-6 is no different from that of Ariane-1; to assure European independent access (both institutional and military) to space. The role of that launcher in the commercial market will again be secondary.
The leading role of Arianespace for GTO is nice but not exactly generating a lot of profit. The current models of Ariane-5 are so expensive that ESA needs to pour in millions of Euro's each year, just for Arianespace to break even. Despite Astrium promising otherwise I personally don't think that will change with the arrival of Ariane-5 ME.

[Rugoz]

During the last months I was working on an ESA study for new launch service concepts, including detailed cost estimates for different launcher solutions. For me the most interesting result is that an all cryogenic launcher, using 3 Vulcain 3 engines (optimized for sea level operation) in the first and one Vinci in the second stage and no additional boosters leads to similar cost as all the solid launcher versions that we investigated. The reference mission for all concepts was defined with 6500 kg to a GTO trajectory.

The cost argument is the one mostly heard when the solid vs. liquid discussion is going on, because, as we all know, a solid stage is less costly than a liquid stage. But the truth is that solid launch vehicles always need at least one stage more to reach GTO than the liquid launchers and therefore, on the systems level, lead to about the same systems cost.

In case of the next European launcher we have to take into account higher development cost for a solid compared to an all cryogenic launcher, much higher development risks for the large (in some concepts segmented) CFRP solid motor casings, the higher dynamic loads for the upper stage and payload and, for me the most important argument, the loss of the large liquid engine technology in Europe!

You seem to have more information available than we have. At what launch rate are the solid and liquid designs equal in terms of costs?

Regarding the loss of liquid engine technology. I don't understand this argument. Just because you stop manufacturing vulcain engines doesn't mean all the knowhow will suddenly vanish.

Also if Ariane 6 should be competitive its not helpful to subsidize certain industries just because some people happen to like them.

People want to know why solids are hated.

This is why.

Goverments insist on them even though they're crap technology compared to kerolox.

The Russians and SpaceX are the only rocket scientists with brains still operating.

Sorry for the tone of this post but if ESA wants to build a solid Ariane 6 I believe that's absolute stupidity.

People don't build steam trains. Why? There's better.

It's the same with solid rocket fuel.

Very convincing arguments 

[asmi]

Regarding the loss of liquid engine technology. I don't understand this argument. Just because you stop manufacturing vulcain engines doesn't mean all the knowhow will suddenly vanish.

Really? Have you ever wondered why US is desperately trying to catch up in kerolox engines technology with the Russians, and russian engines are still superior in just about every aspect that matters - more reliable, cheaper, simpler, higher performance. They also once thought that "oh this is impossible to do", and "we'll get back on it later", until they've suddenly discovered that it's actually IS possible, and they are still inferior in that technology. The problem is that technologies in space industry are not static, they evolve rather quickly, and what is considered "good" now will become obsolete much quicker than you think.

As for this ESA's decision - I think it's nonsence from technological point of vew, but this decision has nothing to do with technology, and everything to do with politics.

[woods170]

Regarding the loss of liquid engine technology. I don't understand this argument. Just because you stop manufacturing vulcain engines doesn't mean all the knowhow will suddenly vanish.

Really? Have you ever wondered why US is desperately trying to catch up in kerolox engines technology with the Russians, and russian engines are still superior in just about every aspect that matters - more reliable, cheaper, simpler, higher performance. They also once thought that "oh this is impossible to do", and "we'll get back on it later", until they've suddenly discovered that it's actually IS possible, and they are still inferior in that technology. The problem is that technologies in space industry are not static, they evolve rather quickly, and what is considered "good" now will become obsolete much quicker than you think.

As for this ESA's decision - I think it's nonsence from technological point of vew, but this decision has nothing to do with technology, and everything to do with politics.

Yes. And you should also remember that politics is exactly the reason why the Ariane series of launchers exists in the first place.

[asmi]

Yes. And you should also remember that politics is exactly the reason why the Ariane series of launchers exists in the first place.

True. But as spaceflight enthusiast I don't give a damn about politics. That's why I agree with the post above that this decision is, politely speaking, "not wise".

[baldusi]

I see this in another way. Since ATV is going to be cancelled, and no crew capsule is expected, Ariane 5 payload capacity is not needed. But they are spending a lot of money en Soyuz launches. Which not only means additional budget on top of the Ariane 5 subsidy, but also goes outside of EU members.
Thus, a more expensive LV that actually replaces the Soyuz and allows to launch the heaviest satellites (6.5tonnes to GTO) they might actually spend less money. And surely less foreign currency.
I still think that the critical issue is which generates the lowest cost, since that would reduce the amount of subsidies and maximize the high tech jobs. But on the other hand, French ICBM are the only truly European nuclear technology, since UK uses American rockets and are not that into the EU.
If I had to think like a politician, I would think that this is a way to keep an European ICBM industrial base, for the strange case that an European Defense Forces are formed in the future. If they have German, Italian and Spanish companies subcontracting, then the prospective transition to a full European Nuclear Triad would be easier.
Of course this is sort of far in the future, but good leaders look into the next century. Please remember that the European Coal and Steel Community was made exactly to make the weapon production a crossed ownership system. This might be the first step to make the ICBM production a pan European system.
Regrettably, the rest of nuclear policy of Germany, Italy and Spain makes it impossible to make a pan European nuclear head system.

[spectre9]

Very convincing arguments 

It's not an argument any more.

It's a fact that gets ignored.

Kerolox > solids

The difference is both performance and price now. Casting and transporting solids cost big dollars and the lost payload over time of making your rocket heavier don't make sense.

There's building solid rockets because they're the right option and there's building solid rockets because of refusal to develop better liquid alternatives which Russia/Soviets have had for over 50 years.

[tobi453]

To me the case is clear: A solid Ariane 6 is a dead end! The next European launcher should be an all cryogenic, two stage concept without strap-on-boosters.

What do you think?

Spacediver

Spacediver, I'm from germany and you are absolutely right. I dont know what CNES is thinking, but this is the end of european space transportation.

I am astonished that no public figure of the european spaceflight community has named this concept what it is - rubbish.

This spacenews article makes it pretty clear that the solid concept has been selected:
http://www.spacenews.com/article/cnes-sets-%E2%80%9Ctriple-seven%E2%80%9D-goal-for-ariane-6-rocket

The design of the rocket — two solid-fueled lower stages and a cryogenic upper stage, plus solid-fueled strap-on boosters — was frozen Nov. 21 during a meeting of ESA government ministers.ESA Launcher Director Antonio Fabrizi said this design, and no other, is what ministers approved.

[edkyle99]

In the aftermath of the conference voices of ESA officials could be heard that a decision towards an all solid Ariane 6 (except for the cryogenic upper stage) is already made.

"Liberty" (of a sort) lives. 

 - Ed Kyle

[IRobot]

Regrettably, the rest of nuclear policy of Germany, Italy and Spain makes it impossible to make a pan European nuclear head system.

As Anne Coulter's nuke threat to France is nonsense, the only credible nuclear threat to Europe (that would require a nuclear response) is China.
Russia is making too much money to go to war. And their billionaires love the Med!

France alone has more nukes than China. England has almost as much as France. Germany has 10 US nukes. So Europeans don't see any need to increase nuclear arsenal. And there hasn't  been bloodlust around here in the past 60 years...

[Rugoz]

Really? Have you ever wondered why US is desperately trying to catch up in kerolox engines technology with the Russians, and russian engines are still superior in just about every aspect that matters - more reliable, cheaper, simpler, higher performance.

It's a fact that gets ignored.

Kerolox > solids

The difference is both performance and price now. Casting and transporting solids cost big dollars and the lost payload over time of making your rocket heavier don't make sense.

That is all nice but as far as I can remember kerolox was never seriously considered for ariane 6. In the end it was multiple vulcains vs solids.

This spacenews article makes it pretty clear that the solid concept has been selected:
http://www.spacenews.com/article/cnes-sets-%E2%80%9Ctriple-seven%E2%80%9D-goal-for-ariane-6-rocket

70m euros per launch, 4-5bn development costs. Sound like a bad deal. For that amount of money I would expect something fancy.

[spectre9]

It's a fact that gets ignored.

Kerolox > solids

The difference is both performance and price now. Casting and transporting solids cost big dollars and the lost payload over time of making your rocket heavier don't make sense.

That is all nice but as far as I can remember kerolox was never seriously considered for ariane 6. In the end it was multiple vulcains vs solids.

I thought there was an option to purchase Russian engines?

Just buy RD-180 and build an Atlas V copy.

I think they want to. If they can't make a Falcon 9 or a Soyuz themselves it's a good option.

[asmi]

That is all nice but as far as I can remember kerolox was never seriously considered for ariane 6. In the end it was multiple vulcains vs solids.

I've brought this up as example of what will happen if you "keep technology" without improving it. US is literally paying quite a price for that oversight, and Europe doesn't want to learn from other's mistakes by making their own. But honestly I don't think they've chosen solids because they didn't realize how stupid this decision is - I'm pretty sure that at least their engineers realize full well what's gonna happen - but it's not the engineers who get to make a call on that - it's politicians, and they don't give a damn about anything that doesn't provide them immediate and tangible benefits. The same btw is happening in US Congress now:
Congress: We want NASA to go to the asteroid and build SLS for that.
NASA: But we can't unless we bring asteroid close enough
Congress: Fine, then we want NASA to go to Mars and build SLS for that.
NASA: But we can't do that either since we've got no money for mission module, and astronauts can't live for half a year in a tin can.
Congress: Fine, we don't really care where will you go, but you must build SLS for that.

[sdsds]

For the proposed "PPH" scheme would the stages be stacked at the pad? In an existing integration facility? In a new one? Or is there as yet no proposal regarding that?

[edkyle99]

The proposed P7C design in really interesting.  It seems to have come out of the woodwork in recent months.  Two basic propulsion units combined in different ways to create a family of launchers that could be somewhat optimized to the payload.  The solids would be cutting edge - better than any other solid produced anywhere on earth.  The upper stage would be the world's most efficient upper stage, hands down. 

Could this be a Falcon killer?

 - Ed Kyle

[Rugoz]

I've brought this up as example of what will happen if you "keep technology" without improving it. US is literally paying quite a price for that oversight, and Europe doesn't want to learn from other's mistakes by making their own. But honestly I don't think they've chosen solids because they didn't realize how stupid this decision is

They've chosen solids because a) the military likes them and b) because maybe solids aren't a bad option after all. Everybody keeps saying kerolox is so much cheaper than solids without providing any numbers.

The hatred for solids seems to come from the fact that reusability is ruled out from the start. I agree this sucks.

To my knowledge solids are not low tech, to the contrary, so I wouldn't say its just keeping tech instead of improving it.

Could this be a Falcon killer?

70m per launch doesn't sound like a falcon killer, but it may at least be competitive, on condition that spacex must bury its reusability plans.

[IRobot]

My hate for solids is due to the inability to do engine cut off.

[mmeijeri]

That's not important for Ariane's official mission, which is to provide assured access to space for institutional payloads.

[Hauerg]

In the aftermath of the conference voices of ESA officials could be heard that a decision towards an all solid Ariane 6 (except for the cryogenic upper stage) is already made.

"Liberty" (of a sort) lives. 

 - Ed Kyle

No Vulcain, no Liberty.

[aquanaut99]

My hate for solids is due to the inability to do engine cut off.

My dislike stems more from the fact that solids are inefficient and enviro-unfriendly (strange to see the otherwise green-minded Europeans, especially the Germans, agreeing to this; my guess is the French military-industrial complex must have pressured really hard).

The inability to cut off, while bad, is less of a deal for Ariane-6, since no astronaut will ever fly on it and it will never be man-rated. I do agree, however, that, for a rocket that is to fly people, lack of cut-off should be an absolute no-go. And, yes, that means that we should never have flown people on Shuttle for 30 years and that SLS is a bad idea. I have said so before and will say so again: solids are not for manned spaceflight!

All in all, I am very disappointed that Europe will, most likely, chose this design. IMO it is the worst of the proposals and will cause them to lose all they have accomplished so far.

[Rugoz]

Hey found a movie

[tobi453]

Germany and idustry wanted the Ariane 5 ME and they got what they wanted. France wanted the A6 and gave in. Thats the reason germany and industry can't speak up against the A6, at least not for the next several months and after that it could be too late. The only realistic option to stop this mess now is by germany denying money in 2014 at the next ministerial council. Italy and France are perfectly fine with this concept.

Many commentators interpreted the results of the ministerial council that germany won the Ariane argument by getting ME. Maybe this assessment was false.

Here are some reason why this concept is bad:
1. First stage liquid propulsion knowledge will be lost
2. Europe gives up on reusability for the next 50 years, because of 1.
3. Europe gives up on manned spaceflight. Currently manned spaceflight is not a priority in Europe but someday the debt crisis will hopefully by over and if the rocket could be easily modified for manned spaceflight like Atlas 5 there could be a chance. With this solid concept there is no chance at all
4. The rocket has no growth potential
5. The Ariane review determined that the rocket can only be cheaper if the industrial structure is fundamentally changed. I don't see this happening here, I don't think the cost target of 70 M Euros can be met. Dordain had the right idea with NELS (New european launch service) but that seems far away now. I wonder whether ESA will ever release some results of the studies going on at the moment
6. Solid is a dead end in the long term, the whole exercise is a waste of money. The money should instead be spent on something with a future: CH4/LOX or something similar
7. No perspective for the young people in Europe interested in space transportation. In 50 years europe will still be doing the same as today: stagnation.

I could entirely be possible that SpaceX will take the leading position from Arianespace in lets say the next 10 years due to its excellent strategic management.

[Rugoz]

^

Oh come on now you're being ridiculous. For reusability a new engine would have to be developed from scratch anyway.

If they build skylon and this I will be more than satisfied 

[IRobot]

My dislike stems more from the fact that solids are inefficient and enviro-unfriendly (strange to see the otherwise green-minded Europeans, especially the Germans, agreeing to this;

German people are environment friendly. Their industry is not. They are the #5 consumer of coal in the world.

[Rugoz]

By the way when we talk about solids, maybe it would make sense to make them reusable. After all they're stable enough such that you only have to attach a parachute to it and let them drop in the ocean.

[apace]

By the way when we talk about solids, maybe it would make sense to make them reusable. After all they're stable enough such that you only have to attach a parachute to it and let them drop in the ocean.

Always had the idea, that reusable solids are same expensive as new solids...

[woods170]

To me the case is clear: A solid Ariane 6 is a dead end! The next European launcher should be an all cryogenic, two stage concept without strap-on-boosters.

What do you think?

Spacediver

Spacediver, I'm from germany and you are absolutely right. I dont know what CNES is thinking, but this is the end of european space transportation.

I am astonished that no public figure of the european spaceflight community has named this concept what it is - rubbish.

This spacenews article makes it pretty clear that the solid concept has been selected:
http://www.spacenews.com/article/cnes-sets-%E2%80%9Ctriple-seven%E2%80%9D-goal-for-ariane-6-rocket

The design of the rocket — two solid-fueled lower stages and a cryogenic upper stage, plus solid-fueled strap-on boosters — was frozen Nov. 21 during a meeting of ESA government ministers.ESA Launcher Director Antonio Fabrizi said this design, and no other, is what ministers approved.

I disagree. This design is not rubbish, not from a political viewpoint. And all of you should remember that ESA decisions for new launchers are more based on political arguments than technical aspects.
Like the United States there has never been doubt inside the ESA political echelons about the use of solids, even on vehicles that were supposed to be flown manned. Ariane-5 was, after all, initially designed as the launch vehicle for the crewed Hermes space shuttle.
With the US space shuttle now gone the two biggest solid boosters on the planet fly on every Ariane-5 mission. From a political viewpoint it is clear as glass: the Ariane solids (never mind the difference between the ones used on Ariane-2, Ariane-4 or Ariane-5) have never given any trouble on any of the launches involved. The liquid technology however has given trouble, on a number of launches.
From the viewpoint of a technically ill-informed politician it is clear: solid technology on European launchers is more reliable than liquid technology. And that "fact" was heavily pushed by CNES.

The ESA politicians also recognize the fact that the current Vulcain technology is a dead-end. You don't go anywhere if you don't develop a new, more powerfull, more reliable, more economic hydrolox engine. That costs big money. And don't forget the role of Vega. The Italians, along with the French have set the stage for very advanced solids technology thru the development of Vega. Developing the first two stages for Ariane-6 will be the next logical step coming forth from the Vega development program.

[woods170]

By the way when we talk about solids, maybe it would make sense to make them reusable. After all they're stable enough such that you only have to attach a parachute to it and let them drop in the ocean.

Always had the idea, that reusable solids are same expensive as new solids...

Correct, if the flight-rate is low enough. That's why Ariane-5 has disposable solids.
The sole reason why on a few Ariane-5 flights the solids were recovered (by means of parachute) was post-flight inspection to validate the design.

[edkyle99]

With this solid concept there is no chance at all
4. The rocket has no growth potential

I disagree, respectfully. 

The performance of an all-liquid rocket would grow by increasing first stage engine thrust, second stage specific impulse, and stretching all of the tanks. 

A solid-liquid rocket would be able to grow in the same way.  The first stages could be stretched to increase thrust, the propellant formulation could be improved, and/or the dry mass could be shaved.  Nozzles could be redesigned to improve specific impulse, and so on.  The second stage could be improved in the same way as for the all-liquid rocket.

 - Ed Kyle

[edkyle99]

My dislike stems more from the fact that solids are inefficient and enviro-unfriendly.

The new all-solid Ariane 6 designs would burn less solid propellant per launch than Ariane 5.  The ability to tailor the launch vehicle to the payload should mean less solid burned overall, over time, compared to Ariane 5.  Finally, the more efficient solids should reduce propellant mass burn requirements.

 - Ed Kyle

[asmi]

Like the United States there has never been doubt inside the ESA political echelons about the use of solids, even on vehicles that were supposed to be flown manned. Ariane-5 was, after all, initially designed as the launch vehicle for the crewed Hermes space shuttle.

There is a huge difference between combined solid-liquid rocket and all-solid rocket. Latter can not be used for manned flight because for that you need throttling and early cut-off capability, and it's not possible with solids.  That is exact reason why first phase of Shuttle flight didn't have abort capability. So going all-solid == no manned missions now (and quite possibly never).

With the US space shuttle now gone the two biggest solid boosters on the planet fly on every Ariane-5 mission. From a political viewpoint it is clear as glass: the Ariane solids (never mind the difference between the ones used on Ariane-2, Ariane-4 or Ariane-5) have never given any trouble on any of the launches involved. The liquid technology however has given trouble, on a number of launches.
From the viewpoint of a technically ill-informed politician it is clear: solid technology on European launchers is more reliable than liquid technology. And that "fact" was heavily pushed by CNES.

Are you comparing few dozens of launches with 2000+ launches done by liquid rockets? Sorry, but you can't say solids are more reliable unless you've got comparable number of flights, now liquids win this race hands down.

The ESA politicians also recognize the fact that the current Vulcain technology is a dead-end. You don't go anywhere if you don't develop a new, more powerfull, more reliable, more economic hydrolox engine. That costs big money. And don't forget the role of Vega. The Italians, along with the French have set the stage for very advanced solids technology thru the development of Vega. Developing the first two stages for Ariane-6 will be the next logical step coming forth from the Vega development program.

That is their investment in the future. As much as you'd like to think otherwise, solid is a dead-end technology. There is only so much one can do to improve it, and there are quite a number of issues which appears to be non-solvable - ISP of solids is rather low (so fuel fraction is bigger, and overall performance is worse for given liftoff mass), cross-feed and refueling are both impossible, reusability is also very questionable.
Liquids, on the other hand, offer a lot of possibilities, and area of possible improvements is vast. If Europeans doesn't like paying Russia for RD-180 or some other kerolox engine, they can license it and build it inside Europe, sure this would be quite an investment, but after european scientists and engineers learn how RD-engines family are built and work, they can improve on top of this baseline instead of starting from scratch.

So I stand by my point that they've picked the worst possible option.

[tobi453]

Ed, of course you are right. I should have said limited growth potential. If you look at Ariane 5 Europe managed to almost double the performance from the initial version (Ariane 5 G) 6->12 tonnes (ME). I don't think this is feasible with this concept. With a liquid concept you could develop a heavy variant (like Delta IV, Falcon).

@woods170: I completely agree, politics is a very important in Europe and because of that the rocket is not going to be competitive without subsidies. The politicians are deceiving themselves when they think that this is going to work with a strict GEO return policy.

As for technology: Liquid propulsion would of course also require a major development effort (maybe LH2 staged combustion, Methane or something else), but it would not be wasted money in the long term. It all comes down to the question whether you think reusability is going to work out or not.  If we give up the knowhow on liquid first stage propulsion it will be very difficult to catch up again once someone develops a (partial) reusable system.

[IanO]

The proposed P7C design in really interesting.  It seems to have come out of the woodwork in recent months.  Two basic propulsion units combined in different ways to create a family of launchers that could be somewhat optimized to the payload.  The solids would be cutting edge - better than any other solid produced anywhere on earth.  The upper stage would be the world's most efficient upper stage, hands down. 

Could this be a Falcon killer?

 - Ed Kyle

It looks like the proposed LAPAN RPS-420 microsat launch architecture (3xsolid / 1xsolid / then uppers), but of course hugely scaled up!

[Rugoz]

Are you comparing few dozens of launches with 2000+ launches done by liquid rockets? Sorry, but you can't say solids are more reliable unless you've got comparable number of flights, now liquids win this race hands down.

Obviously he's talking about the Ariane 5 program. Also solid rockets probably have been used like a billion times, not the same size but still.

As much as you'd like to think otherwise, solid is a dead-end technology. There is only so much one can do to improve it, and there are quite a number of issues which appears to be non-solvable - ISP of solids is rather low (so fuel fraction is bigger, and overall performance is worse for given liftoff mass), cross-feed and refueling are both impossible, reusability is also very questionable.
Liquids, on the other hand, offer a lot of possibilities, and area of possible improvements is vast.

Solids have improved quite a lot, at least when it comes to weight. The ISP of solids is rather low, but so is the ISP of kerolox. Liquids offer more possibilities, but that doesn't necessarily make the more economical.

Still I agree that reusability is not an option with solids, but do we know how reusability will look like? If it will be something along the lines of skylon there is no point in starting another high thrust engine program now. In fact in such a case going with solids is reasonable because it satisfies potential military needs which a reusable launcher can't.

Ed, of course you are right. I should have said limited growth potential. If you look at Ariane 5 Europe managed to almost double the performance from the initial version (Ariane 5 G) 6->12 tonnes (ME). I don't think this is feasible with this concept. With a liquid concept you could develop a heavy variant (like Delta IV, Falcon).

Actually improvements to the EAP (boosters), EPC (first stage) and EPS (upper stage) all added approximately the same to GTO performance.

[Proponent]

My hate for solids is due to the inability to do engine cut off.

Thrust termination for solids isn't out of the question.  The burn rate of solids generally goes as a power of the pressure, with index greater than one.  Vent the casing and the pressure will drop.  Thrust-termination ports were planned for the solids that the Air Force was going to use on the Titan III-M when launching the Manned Orbiting Laboratory.  Blowing the nozzle off has also been suggested.  Whether this is a good idea or not is another question; I'm just pointing out that the blanket statement that solids can't be shut down isn't true.

I think the biggest arguments against solids for human missions are that their failure modes are not graceful.  The entire casing is a critical area, whereas in a liquid-propellant engine only the small engine itself (including pumps, combustion chamber and nozzle) is critical.  It's therefore easier to monitor a liquid's health and shut it down if things start to go wrong.  If a solid fails, it's more likely to be spectacular, whereas when liquids fail they don't usually blow up and tear the vehicle apart.  And if if a solid were to fail non-spectacularly, there's no possibility of re-routing its propellant to another engine, as there is with a liquid.

All of that said, small solids like those of used on Atlas V (which are not segmented and don't have thrust-vector control) have very good records.  For example, over a thousand were launched on Delta IIs with just one outright failure (and one which failed to separate).  Hence, I suspect that adding a small solid or two to a liquid stage doesn't add much risk.

[Proponent]

How do the solids proposed for Ariane 6 compare in size with Vega's first stage?  Is there a synergy?

I agree with the comments above that, when you consider all factors, this design makes a lot of sense for ESA.  It keeps production going for large solids, which the military will like.  Ariane 5, despite subsidies, is becoming uncompetitive, so if ESA's giving up on commercial launches, Ariane 6 will fly infrequently, so solids may well offer the lowest cost.

Once Ariane 5 is gone, the only launch vehicle with segmented solids will be SLS.

[sdsds]

The P7C design for Ariane 6 would reportedly use a P135 motor, as compared with the P80 motor currently used for the Vega first stage. An Ariane 6 with the new motor, “could facilitate new development of a more powerful Vega engine that could lower production costs and greatly improve its competitiveness in the commercial smallsat market.

“For Vega, we want a P120 at a minimum,” says Enrico Saggese, head of Italian space agency ASI.

http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_10_15_2012_p26-505016.xml&p=3

[Proponent]

Thanks.

[mmeijeri]

1. First stage liquid propulsion knowledge will be lost

Do you work on Ariane's core stage liquid propulsion yourself?

[tobi453]

No, I don't work on Ariane at all. I'm just a poor student concerned about the european space program. So don't believe everything I'm writing.

[Rugoz]

Maybe someone working on those ariane 6 studies could present us some rough cost estimates, if its not confidential  .

If you look at the ariane 5 cost breakdown there is no way you can offer the launch of an all liquid launcher with 3 vulcain engines for 70m.

The P7C however seems at least feasible on paper for 70m.

[mmeijeri]

If you look at the ariane 5 cost breakdown there is no way you can offer the launch of an all liquid launcher with 3 vulcain engines for 70m.

Do you have a link for that? I imagine a large part of the costs are fixed costs and a large part of those fixed costs are related to the solids.

[Patchouli]

It's a fact that gets ignored.

Kerolox > solids

The difference is both performance and price now. Casting and transporting solids cost big dollars and the lost payload over time of making your rocket heavier don't make sense.

That is all nice but as far as I can remember kerolox was never seriously considered for ariane 6. In the end it was multiple vulcains vs solids.

I thought there was an option to purchase Russian engines?

Just buy RD-180 and build an Atlas V copy.

I think they want to. If they can't make a Falcon 9 or a Soyuz themselves it's a good option.

Spacex and the Russians along with ULA's Atlas V seem to suggest kerolox is the way to go if you want the cheapest and most reliable first stage possible.

If they want a jobs program Snecma should be able to easily produce a large kerolox engine.
To get started quickly they could license the RD-180 or even an engine like the Tr-107 or F-1A or AJ-26-500.

A single RD-180 or F-1 first stage plus a cheap second stage might be able to deliver on the 70M target yet still be able to offer larger payloads with the addition of a better upper stage.
Maybe even use a cut down Vega first stage for the low end vehicle's second stage.

[woods170]

To quote Jim: Rockets are not Lego's.

[Rugoz]

Do you have a link for that? I imagine a large part of the costs are fixed costs and a large part of those fixed costs are related to the solids.

Don't know what you mean by fixed costs in this context, but the facility for casting boosters with 3m diameter is already up and running in kourou, the more you use it the better.

I posted this in another thread, however the numbers are from a german blog and only estimates which may be simply wrong:

I found a nice calculation on a german site:

Ariane 5

Production cost: 114m (not launch cost, based on arianespace's purchase of 35 rockets for 4bn)

Boosters: ~25m
Vulcain: ~15m
Upper stage: ~20m
EPC (incl. vulcain), VEB, fairing: 69m

Ok lets assume 3 cheaper vulcains at 30m + 20m upper stage, that is already 50m without boosters and core. 40% cheaper sounds very difficult to achieve.

Spacex and the Russians along with ULA's Atlas V seem to suggest kerolox is the way to go if you want the cheapest and most reliable first stage possible.

The russians and SpaceX also lack the knowhow to design and manufacture large solids.

Also, why are delta IV and atlas V so costly despite resembling the optimal designs many here advocate?

[spectre9]

Atlas V 401 is a beast rocket.

Look at it's stats, no solids 

Everything else with or without solids from the EELV range just doesn't float my boat like the 401.

Kerolox 1st stage, Hydrolox 2nd stage.

That's the way to go for the best performance.

The Russians and SpaceX lose a bit not having the LH2 stage.

[mmeijeri]

Don't know what you mean by fixed costs in this context, but the facility for casting boosters with 3m diameter is already up and running in kourou, the more you use it the better.

fixed costs = costs you incur even if you produce no engines
variable costs = additional costs per engine

If you build N engines, costs would be C = C_fixed + N * C_variable

With 3 * N engines, costs would be C = C_fixed + 3 * N * C_variable

If C_{fixed,average} := C_fixed / N >> C_variable, then total costs for 3 * N engines could be much less than 3 times the costs for N engines, plus you would get to eliminate the fixed and variable costs of the solids.

A similar argument applies to the solids, so it would be interesting to know all the components to determine which option would be cheaper. Just knowing the average costs of an engine at current production numbers doesn't tell you very much.

[cheesybagel]

IMHO Ariane 6 is an interim solution to replace the use of Soyuz for launching the Galileo constellation and other tasks like that. The infrastructure to cast solids is already there in Kourou where it is used for both P230 and P80. I would not be surprised if they only needed to change the casings and the electronics. This should provide a responsive launch solution for military and other critical payloads at a low R&D cost.

However Ariane 6 does not address the long term requirement for reusable launch which is being embodied in programs like the Volga LOX/LCH4 staged combustion rocket engine and IXV.

Still this is somewhat disappointing. In my opinion liquid rocket engines are the most viable solution for space launch we have. It will also be rather pathetic to witness European liquid rocket engine capabilities crumble just as China gets their staged combustion Long March 5 rocket working. A decade from now European leaders will wonder where their space launch infrastructure went as SpaceX, Chinese, and Russians grab the launch market.

[spacediver]

Wow, only a few days and more than 50 replies!
Obviously it was an urgent problem to be discussed.

I'd like to give some more results from the NELS study but I will not publish any concrete numbers as they are confidential. I hope you understand that I don't want to put my job in jeopardy...

In the study we investigated different launcher concepts, including concepts with LOX/kerosene, LOX / hydrogen and solid first stages, all combined with a cryogenic upper stage. We also investigated different versions of the PPH approach, including the CNES concepts.

The most interesting result is that all modular concepts, using a common core approach or strap-on-boosters, are not competitive to the “clean” inline designs.

The three most promising concepts KH (kerolox first stage with NK-33 engines), HH (cryogenic first stage with Vulcain 3) and PPH (solid first and second stage in-line) have practically the same recurrent cost. The small differences are well within the accuracy of our cost estimates.
Therefore, no economic justification for a solid Ariane-6 design can be derived from these results!   

BTW, no concept is able to meet the 70M Euro benchmark for 6,5t to GTO.

Taking into account the loss of crucial technology, for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

The development cost for the HH concept are in the same range as for the solid concepts, but the development risk is much lower as the Vulcain engines are well understood and the V3 is directly derived from the V2. Also the main stage tank is nothing but a stretched version (with different wall thickness of course) of the existing EPC stage.

The development time is also shorter. A “Block 1” version of the HH concept, using Vulcain 2 engines with shortened nozzles instead of the Vulcain 3 and the Ariane 5ME upper stage could be launched already in 2018! It would have a GTO payload capacity of only 4,3 t but it can be used to qualify the first stage prior to the availability of the Vulcain 3.

In my eyes it is a shame that such a concept is not even given a fair chance to compete against the PPH in a phase A study.

Spacediver

[mmeijeri]

The most interesting result is that all modular concepts, using a common core approach or strap-on-boosters, are not competitive to the “clean” inline designs.

Competitive is in the eye of the beholder. You can tweak your assumptions to get the outcome you want.

The three most promising concepts KH (kerolox first stage with NK-33 engines), HH (cryogenic first stage with Vulcain 3) and PPH (solid first and second stage in-line) have practically the same recurrent cost.

What about fixed vs variable costs?

The small differences are well within the accuracy of our cost estimates.
Therefore, no economic justification for a solid Ariane-6 design can be derived from these results!   

Or against it.

BTW, no concept is able to meet the 70M Euro benchmark for 6,5t to GTO.

Interesting.

Taking into account the loss of crucial technology, for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

Do you work on liquid engines yourself?

The development cost for the HH concept are in the same range as for the solid concepts, but the development risk is much lower as the Vulcain engines are well understood and the V3 is directly derived from the V2. Also the main stage tank is nothing but a stretched version (with different wall thickness of course) of the existing EPC stage.

Did the study look at a triple Vulcain 2 variant?

[Rugoz]

The most interesting result is that all modular concepts, using a common core approach or strap-on-boosters, are not competitive to the “clean” inline designs.

The three most promising concepts KH (kerolox first stage with NK-33 engines), HH (cryogenic first stage with Vulcain 3) and PPH (solid first and second stage in-line) have practically the same recurrent cost. The small differences are well within the accuracy of our cost estimates.
Therefore, no economic justification for a solid Ariane-6 design can be derived from these results!   

BTW, no concept is able to meet the 70M Euro benchmark for 6,5t to GTO.

Taking into account the loss of crucial technology, for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

Interesting, can you provide us with a cost breakdown, core stage, vulcains, upper stage?

Have you also looked at the P7C design?

[MikeAtkinson]

spacediver,

did you look at any reusable options?

Although the KH, HH and PPH options were similar in the cost estimates for 6.5 T to GTO, where there significant differences in either payload to LEO or payload for BEO orbit missions?

[sdsds]

results from the NELS study

Thanks very much for providing this overview!

In addition to the questions from others:

for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

On other threads people have suggested propellant offload approaches like this, and had their ideas shot down by assertions from professionals that first stage propellant offloading just isn't done. (It came up most prominently in the AJAX thread, if I remember correctly. But also in discussions of other cores that might use 3 or 4 engines depending on the mission.) So, is this concept considered to be "low risk" in general? Or were there specific aspects of the core using Vulcain-3 engines that made it possible?

[Patchouli]

To quote Jim: Rockets are not Lego's.

They're kinda already doing that with some of the variants to get commonality with Vega.

One issue with Araine 5 it's now too small for double GTO launches as a typical geostationary satellite today is nearly twice the mass one was back in the 80s but overkill for a single comsat.

The best course would seem to be to try and emulate LVs like Falcon and Angara.





 

[woods170]

One issue with Araine 5 it's now too small for double GTO launches as a typical geostationary satellite today is nearly twice the mass one was back in the 80s but overkill for a single comsat.

Yeah, same problem that killed Ariane 4. For Ariane 5 it will be (temporarily) solved by the arrival of Ariane 5 ME. But that's it. After that they will have to revert back to single payload launches. Hence the main driver for Ariane 6.

[bobthemonkey]

Apparently insurers have been assigning lower risk and therefore premiums to single launches, compared to dual setups.

There was also some debate about finding suitable payloads for a dual manifest flight.

[spacediver]

The most interesting result is that all modular concepts, using a common core approach or strap-on-boosters, are not competitive to the “clean” inline designs.

Competitive is in the eye of the beholder. You can tweak your assumptions to get the outcome you want.

No, competitive is a matter of cost! If a certain configuration has 25% higher RC cost than another it will not be competitive vs. that other concept!

The three most promising concepts KH (kerolox first stage with NK-33 engines), HH (cryogenic first stage with Vulcain 3) and PPH (solid first and second stage in-line) have practically the same recurrent cost.

What about fixed vs variable costs?

Share of fixed cost is a bit higher for the liquid concepts, giving the solids a small advantage at low launch rates.

The small differences are well within the accuracy of our cost estimates.
Therefore, no economic justification for a solid Ariane-6 design can be derived from these results!   

Or against it.

Yes, but if cost can not drive the decision, I normally would choose the technology with the better future prospects. And that is definitely LOX/hydrogen!

BTW, no concept is able to meet the 70M Euro benchmark for 6,5t to GTO.

Interesting.

Taking into account the loss of crucial technology, for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

Do you work on liquid engines yourself?

No, not anymore.

The development cost for the HH concept are in the same range as for the solid concepts, but the development risk is much lower as the Vulcain engines are well understood and the V3 is directly derived from the V2. Also the main stage tank is nothing but a stretched version (with different wall thickness of course) of the existing EPC stage.

Did the study look at a triple Vulcain 2 variant?

No, the Vulcain 2 as used today has too low lift of thrust as it is optimized for altitude operation. You'd need at least 4-5 Vulcain 2 to get off the pad.

BTW: the Vulcain 3 I refer to is a low cost version of the Vulcain 2 with simplified components. Optimized for sea level operation with a much lower expansion ratio, lower ROF, slightly increased combustion pressure but still GG cycle.

[pippin]

Apparently insurers have been assigning lower risk and therefore premiums to single launches, compared to dual setups.

Source? Arianespace claims that Ariane 5 has the lowest insurance premiums in the business and they always do dual launches for commercial launches.

[spacediver]

The most interesting result is that all modular concepts, using a common core approach or strap-on-boosters, are not competitive to the “clean” inline designs.

The three most promising concepts KH (kerolox first stage with NK-33 engines), HH (cryogenic first stage with Vulcain 3) and PPH (solid first and second stage in-line) have practically the same recurrent cost. The small differences are well within the accuracy of our cost estimates.
Therefore, no economic justification for a solid Ariane-6 design can be derived from these results!   

BTW, no concept is able to meet the 70M Euro benchmark for 6,5t to GTO.

Taking into account the loss of crucial technology, for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

Interesting, can you provide us with a cost breakdown, core stage, vulcains, upper stage?

Have you also looked at the P7C design?

Of course I have all that data available, but I can not post it here. We made cost and mass breakdowns with 50 to 70 line items per launcher configuration. The cost estimates are based on information from external partners (e.g. engine manufacturers) and common cost estimation tools. That tools were calibrated to known cost breakdowns of existing launchers.

Yes, we also investigated a similar design like P7C.
It's RC cost is about 2% higher than for HH. It was one of the most expensive solid configurations that we investigated due to the high number (5) of propulsive modules.

[spacediver]

results from the NELS study

Thanks very much for providing this overview!

In addition to the questions from others:

for me the clear winner is a HH concept using 3 Vulcain-3 engines in the first stage for the large payloads (up to 6,5 t) and two engines on the same first stage with a 35% propellant offload for the small payloads (up to 3,5 t).

On other threads people have suggested propellant offload approaches like this, and had their ideas shot down by assertions from professionals that first stage propellant offloading just isn't done. (It came up most prominently in the AJAX thread, if I remember correctly. But also in discussions of other cores that might use 3 or 4 engines depending on the mission.) So, is this concept considered to be "low risk" in general? Or were there specific aspects of the core using Vulcain-3 engines that made it possible?

Prop offload was done with Ariane 40. the version without boosters. It could not lift off fully fueled.

If you look on the small launcher version isolated from the overall concept, it would be a bad design to use a too large fuel tank that you do not need, but regarding the fact that only 20% of the expected payloads are in the bandwidth of the "small" launcher it would not justify the development and production of a shorter tank version.
You'd need to run a separate production line, even if there is a high comonality in components, and you need to know very early in the production process if you need a standard or small launcher.

The cost saving is only one engine for the small launcher, but you can decide very late in the stage production process (only a few weeks prior to delivery of the stage) if you need to mount 2 or 3 engines.

The only real risk I see is some base heating problem when the center engine is missing, but this could be addressed by proper thermal protection design.

[mmeijeri]

No, competitive is a matter of cost! If a certain configuration has 25% higher RC cost than another it will not be competitive vs. that other concept!

You didn't respond to my main argument: you can tweak your assumptions to get the outcome you want. Just try a long list of slightly different assumptions, and see which makes your preferred solution come out best, then set that as your official goal. I'm sure that happens all the time. I've seen amusing examples of this relating defence spending of NATO countries to GDP, population, area, total length of borders, GDP/capita etc etc. Almost every country could point to a statistic that showed they were spending more than others. Remember, there are lies, damned lies and statistics!

Yes, but if cost can not drive the decision, I normally would choose the technology with the better future prospects.

Bear in mind the official goal of Ariane 6 is assured access to space for institutional payloads, not having state of the art propulsion technology. Also, the solids have commonality with ballistic missiles.

And that is definitely LOX/hydrogen!

I'm not so sure about that, neither LOX/LH2 nor solids are ideal as a first stage. They were meant to be used together, that doesn't mean either is good alone.

No, the Vulcain 2 as used today has too low lift of thrust as it is optimized for altitude operation. You'd need at least 4-5 Vulcain 2 to get off the pad.

Hmm, that does not match the numbers I've seen. You could also use a shorter EPC of course.

[Oli]

@spacediver

So did they give your team any reasons why your preferred design was not selected? How many different teams at different institutions/companies were doing such studies anyway?

Regarding the HH concept, how would the first stage compare to the A5 first stage? Propellant load, tank diameter etc.? Is there reason to believe it would be significantly cheaper? You know as a layman it just seems that about the only thing you save from A5 are the 2 boosters, which, to my limited knowledge, don't even remotely make up 40% of A5 launch costs...

Yes, we also investigated a similar design like P7C.
It's RC cost is about 2% higher than for HH. It was one of the most expensive solid configurations that we investigated due to the high number (5) of propulsive modules.

So how would you judge their 70m/launch target? Delusional? Maybe they're just trying to shoot down the whole ariane 6 program 

[spacediver]

You didn't respond to my main argument: you can tweak your assumptions to get the outcome you want. Just try a long list of slightly different assumptions, and see which makes your preferred solution come out best, then set that as your official goal. I'm sure that happens all the time. I've seen amusing examples of this relating defence spending of NATO countries to GDP, population, area, total length of borders, GDP/capita etc etc. Almost every country could point to a statistic that showed they were spending more than others. Remember, there are lies, damned lies and statistics!

So you accuse me, the whole team from different companies, our external partners, our ESA client and our supervising external experts from DLR and other institutions that we manipulated the study results according to our biases?
It is that really what you want to say?

BTW: There was hardly any room for assumptions. We had a bunch of hard requirements from ESA that we had to follow!

One of these requirements was first launch 2020 which threw any reusable or partly reusable solutions out of the scope.

[mmeijeri]

So you accuse me, the whole team from different companies, our external partners, our ESA client and our supervising external experts from DLR and other institutions that we manipulated the study results according to our biases?
It is that really what you want to say?

I didn't accuse anyone of anything. I said competitive is in the eye of the beholder. But yes, everyone is vulnerable to biases. Ask a solid propulsion expert for an answer, and you'll likely get one biased towards solids. If we ask a liquid propulsion person like yourself, we're more likely to get an answer that is biased towards liquids.

BTW: There was hardly any room for assumptions. We had a bunch of hard requirements from ESA that we had to follow!

Perhaps, and I'm happy to believe that's your opinion, but from here it's hard to agree or disagree without seeing the studies in question.

[mmeijeri]

As an aside, are you accusing decision makers of being biased towards solids?

[spacediver]

@spacediver

So did they give your team any reasons why your preferred design was not selected? How many different teams at different institutions/companies were doing such studies anyway?

No. The order came from highest ESA ranks. Even the ESA people that were our direct contacts were not happy with this decision.

For me it is clear that A6 had to be all solid no matter what the results of the studies would be. This is purely politically driven.

For me as a German tax payer it is a nightmare that my money will be used to subsidize french military missiles while our own technological capabilities will decline. I hope that our government will refuse to go that way but I doubt that they really will...

Regarding the HH concept, how would the first stage compare to the A5 first stage? Propellant load, tank diameter etc.? Is there reason to believe it would be significantly cheaper? You know as a layman it just seems that about the only thing you save from A5 are the 2 boosters, which, to my limited knowledge, don't even remotely make up 40% of A5 launch costs...

The first stage tank would be a stretched version (with thicker wall of course) of the A5 EPC. Same tank dome shape, same diameter. Could be made on existing tooling.
The cost reduction would come from the use of only one propellant trechnology (no more solid furl factory in Kourou necessary), less infrastructure cost, horizontal integration etc...

Nevertheless, as all the other concepts, it will never meet the 70M€ target

Yes, we also investigated a similar design like P7C.
It's RC cost is about 2% higher than for HH. It was one of the most expensive solid configurations that we investigated due to the high number (5) of propulsive modules.

So how would you judge their 70m/launch target? Delusional? Maybe they're just trying to shoot down the whole ariane 6 program 

No f***** way that any of the concepts will ever meet the 70M€ target. Not with the current political / industrial landscape.

Maybe it would be  better to stick with A5ME and take more time to develop a partly reusable system until 2030...

[spacediver]

As an aside, are you accusing decision makers of being biased towards solids?

Yes I do, and that is no secret!

Anyone in the European space community knows that ESA and CNES are pushing toward concepts that can subsidize the french military applications.
The Italians are pushing towards solids because of their VEGA which is, at least, something one could understand.

[spacediver]

So you accuse me, the whole team from different companies, our external partners, our ESA client and our supervising external experts from DLR and other institutions that we manipulated the study results according to our biases?
It is that really what you want to say?

I didn't accuse anyone of anything. I said competitive is in the eye of the beholder. But yes, everyone is vulnerable to biases. Ask a solid propulsion expert for an answer, and you'll likely get one biased towards solids. If we ask a liquid propulsion person like yourself, we're more likely to get an answer that is biased towards liquids.

We had external partners from both sides in our team.
And It's not so that all our team members have the same point of view that I have.
Within our team there are lots of colleagues that are quite fine with the solids...

[woods170]

The first stage tank would be a stretched version (with thicker wall of course) of the A5 EPC. Same tank dome shape, same diameter. Could be made on existing tooling.
The cost reduction would come from the use of only one propellant trechnology (no more solid furl factory in Kourou necessary), less infrastructure cost, horizontal integration etc...

Nevertheless, as all the other concepts, it will never meet the 70M€ target

Emphasis mine. That argument does not apply as long as Vega keeps flying.

No f***** way that any of the concepts will ever meet the 70M€ target. Not with the current political / industrial landscape.

Had you actually expected anything else? No single version of Ariane has ever met the predicted cost target. All versions turned out to be (in some occasions much) more expensive then advertised. That's why I don't buy the crap coming from Astrium that the Ariane-5 ME won't need any subsidies. And clearly, that has been recognized by ESA top-brass as well, because they openly questioned that claim.

Maybe it would be  better to stick with A5ME and take more time to develop a partly reusable system until 2030...

The benefits (regardless of them being financial or technical) of (partial) reusability are highly over-rated. IMO that is something a certain new-space company from Hawthorne will discover as well if and when they take reusability of their launchers to the full level. And that is a commercial effort. I don't give anything for (partial) reusable efforts when it's being paid for by an intergovernmental agency like ESA.

[edkyle99]

Anyone in the European space community knows that ESA and CNES are pushing toward concepts that can subsidize the french military applications.

I've wondered about such assertions, in the U.S. too when it comes to ATK and Aerojet.  How does pouring solid motors in Kourou (or SLS SRBs in Promontory) really help French (or U.S.) defense needs?  Military missiles usually use a different, more potent blend of propellant, for example.  Large numbers of military missile motors are needed for the arsenal, while only a relative handful of Ariane 6 or SLS motors would be poured.  No military missiles use any of the space launch tooling.  And so on.

 - Ed Kyle

[arkaska]

Anyone in the European space community knows that ESA and CNES are pushing toward concepts that can subsidize the french military applications.

I've wondered about such assertions, in the U.S. too when it comes to ATK and Aerojet.  How does pouring solid motors in Kourou (or SLS SRBs in Promontory) really help French (or U.S.) defense needs?  Military missiles usually use a different, more potent blend of propellant, for example.  Large numbers of military missile motors are needed for the arsenal, while only a relative handful of Ariane 6 or SLS motors would be poured.  No military missiles use any of the space launch tooling.  And so on.

 - Ed Kyle

R&D?

[Patchouli]

Would it even be possible to manrate the all solid Ariane 6?

[R7]

Would it even be possible to manrate the all solid Ariane 6?

Or 'comsat-rate' for that matter? All solids is going to be a rough ride.

[Lars_J]

Would it even be possible to manrate the all solid Ariane 6?

There really is no such thing as a "man rating". You make it as safe as you can.

The only question is how much risk you are willing to accept.

[Patchouli]

Would it even be possible to manrate the all solid Ariane 6?

Or 'comsat-rate' for that matter? All solids is going to be a rough ride.

You can beef up a comsat to handle a rough ride and so long as it doesn't break on the way up no one is going to complain.

[R7]

You can beef up a comsat ... no one is going to complain.

Except comsat manufacturers and their customers for the price-hike.

[edkyle99]

You can beef up a comsat ... no one is going to complain.

Except comsat manufacturers and their customers for the price-hike.

Solid motors do not guarantee that payloads will suffer high vibration loads.  Methods are available to attenuate vibrations before they reach the payload.

Consider that Ariane 5 and Vega produce similar vibration loads on payloads, according to their user's guides.  Both produce 1g or less sine-equivalent vibration at the payload, though at different frequencies.  Vega produces slightly higher static g-forces.  Ariane 5 produces slightly higher acoustic loads.

 - Ed Kyle

[strangequark]

I've wondered about such assertions, in the U.S. too when it comes to ATK and Aerojet.  How does pouring solid motors in Kourou (or SLS SRBs in Promontory) really help French (or U.S.) defense needs?  Military missiles usually use a different, more potent blend of propellant, for example.  Large numbers of military missile motors are needed for the arsenal, while only a relative handful of Ariane 6 or SLS motors would be poured.  No military missiles use any of the space launch tooling.  And so on.

 - Ed Kyle

You may have a point, if you're talking about missiles in current production. However, when was the last time the US actually built an ICBM? Using solids in spaceflight maintains an industrial base when actually building missiles is frowned upon.There is certainly a level of understanding in government that using solids elsewhere helps.  Who knows the level of pressure exerted by DOD, Congress, etc due to that understanding? That's for conspiracy theorists to work out. As for the commonality, first off, the details can vary while still maintaining critical skills. Secondly, there's still tons of commonality. Every single launch vehicle used by Orbital, for instance, has copious amounts of ICBM heritage.

Current French SLBMs have a direct lineage to the Ariane 5 solids, incidentally.

[woods170]

I've wondered about such assertions, in the U.S. too when it comes to ATK and Aerojet.  How does pouring solid motors in Kourou (or SLS SRBs in Promontory) really help French (or U.S.) defense needs?  Military missiles usually use a different, more potent blend of propellant, for example.  Large numbers of military missile motors are needed for the arsenal, while only a relative handful of Ariane 6 or SLS motors would be poured.  No military missiles use any of the space launch tooling.  And so on.

 - Ed Kyle

You may have a point, if you're talking about missiles in current production. However, when was the last time the US actually built an ICBM? Using solids in spaceflight maintains an industrial base when actually building missiles is frowned upon.There is certainly a level of understanding in government that using solids elsewhere helps.  Who knows the level of pressure exerted by DOD, Congress, etc due to that understanding? That's for conspiracy theorists to work out. As for the commonality, first off, the details can vary while still maintaining critical skills. Secondly, there's still tons of commonality. Every single launch vehicle used by Orbital, for instance, has copious amounts of ICBM heritage.

Current French SLBMs have a direct lineage to the Ariane 5 solids, incidentally.

Or so it is claimed on the Internet. I have yet to see hard evidence for that.
However, the Ariane 5 EAP's are constructed by members of the Europropulsion consortium, under auspices of EADS Astrium. And guess who is responsible for production of the M51 SLBM...EADS Astrium. So, I would not be surprised that there would be direct lineage between EAP and M-51, but I've yet to see hard evidence for that.

[mmeijeri]

So, I would not be surprised that there would be direct lineage between EAP and M-51, but I've yet to see hard evidence for that.

Wikipedia says that, and I believe I've seen other sources say this too.

[mmeijeri]

Using solids in spaceflight maintains an industrial base when actually building missiles is frowned upon.

Unsegmented solids are still used on EELVs and in air-to-air missiles, cruise missiles etc. Wouldn't that be enough to keep the industrial base alive?

[Stephan]

Current French SLBMs have a direct lineage to the Ariane 5 solids, incidentally.

And Ariane 5 (and 4) solids have lineage to previous French SLBM ...

[Oli]

New pic.

[Lars_J]

Yikes. Not elegant. Has there ever been a LV of this size with two parallel first stages?

If they still insist on using solids, I'm still shocked that they don't go for the Atlas V approach, with a varying amount of smaller solid boosters surrounding a slimmer cryogenic core derived from Ariane 5. But I guess *someone* at ESA really likes those large solids.

[Galactic Penguin SST]

New pic.

Hmmm...... why go for an even number of first stage solids and take the pain of designing the 1/2 stage separation plane instead of odd numbers (1,3,5 solids etc.)? 

[woods170]

New pic.

Source? Because we've had two replies already discussing the thing we see, but we have yet to determine the source of this picture.

[Galactic Penguin SST]

New pic.

Source? Because we've had two replies already discussing the thing we see, but we have yet to determine the source of this picture.

Turns out it's from CNES...... http://www.cnes.fr/web/CNES-fr/10692-gp-l-europe-s-elance-vers-ariane-6.php

[woods170]

And an artistic view of this vehicle launching... Take a look at this CNES newspage from november 2012.

Edit:
English version of the link provided by Galactic Penguin above...

[Galactic Penguin SST]

Do we know about what kind of performance are we talking about if we varies to number of P135 solid motors used on the first stage from 1 to 5?

[gosnold]

At least 6.5t GTO with 3 1st stage solids, 3.5t with 2. (Source: audio clip at the bottom of the page http://www.cnes.fr/web/CNES-fr/10692-gp-l-europe-s-elance-vers-ariane-6.php)

[R7]

But I guess *someone* at ESA really likes those large solids.

French navy likes it too, they'll get three tests (minimum) per launch 

[baldusi]

Yikes. Not elegant. Has there ever been a LV of this size with two parallel first stages?

If they still insist on using solids, I'm still shocked that they don't go for the Atlas V approach, with a varying amount of smaller solid boosters surrounding a slimmer cryogenic core derived from Ariane 5. But I guess *someone* at ESA really likes those large solids.

To do the Atlas V approach they would also need to develop an RD-180 and CBC equivalent. The way they propose it, ugly as it might look, means just developing one P135. Much cheaper proposition. I always thought it was going to be at least a P150, thou. I guess that's how they propose to grow the family if they need more performance. As I understanding it, current technology allows for P180 without pushing it too much.
So:
3 x P135+1 x P135+US is 6.5mt to GTO
2 x P135+1 x P135+US is 3.5mt to GTO
1 x P135+US is how much to SSO?

[edkyle99]

Notional views.  The phrase "possible configurations" is applied to the images.  The three solid first stage has been shown in a more practical side-by-side arrangement in other drawings.

There is, as I understand it, still another possible range of PPH designs that would use two serial solid stages of different sizes, with smaller strap-on solids added to tailor the vehicle to its missions.  This design would be more capable than the P135 based design shown here.

 - Ed Kyle

[edkyle99]

But I guess *someone* at ESA really likes those large solids.

French navy likes it too, they'll get three tests (minimum) per launch 

No they won't.  French SLBM's are smaller than P135, smaller diameter and they weigh, all three stages total, nearly 1/3rd as much as a single P135 motor.  I suspect that the propellant formulations would be different, they're obviously not using the same tooling, etc.

 - Ed Kyle

[R7]

French SLBM's are smaller than P135, smaller diameter and they weigh, all three stages total, nearly 1/3rd as much as a single P135 motor.  I suspect that the propellant formulations would be different, they're obviously not using the same tooling, etc.

Same manufacturer. I have difficulties imagining EADS (and ATK too) having two completely separate R&D and production lines for military and civilian products, after creating SLBM they would nab new people blissfully ignorant of any missile tech to Plato's Cave, project pages of Sutton on the wall and then task them to make civilian SRMs from scratch while people experienced with missile motors are twiddling thumbs next door. Nah.

[Lars_J]

Yikes. Not elegant. Has there ever been a LV of this size with two parallel first stages?

If they still insist on using solids, I'm still shocked that they don't go for the Atlas V approach, with a varying amount of smaller solid boosters surrounding a slimmer cryogenic core derived from Ariane 5. But I guess *someone* at ESA really likes those large solids.

To do the Atlas V approach they would also need to develop an RD-180 and CBC equivalent.

No, they already have the CBC equivalent - the current Ariane 5 core - it can be used as a starting point. Now it would never be able to take off without solids, but at least you could replace the Ariane 5 solids with 4-8 smaller solids to fine-tune the performance. Think of it as a hybrid between Ariane 5 and Atlas V.

[Oli]

Same manufacturer. I have difficulties imagining EADS (and ATK too) having two completely separate R&D and production lines for military and civilian products, after creating SLBM they would nab new people blissfully ignorant of any missile tech to Plato's Cave, project pages of Sutton on the wall and then task them to make civilian SRMs from scratch while people experienced with missile motors are twiddling thumbs next door. Nah.

To my knowledge M51 (french SLBM) is being built by Herakles, which also manufactures the nozzle for Vega/EAP and stage seperation for Vega.

The rest of Vega (P80, zefiro 23, zefiro 9) is being built in a factory from Avio in Italy. I guess the P135 casing and thermal protection will come from there.

So there is some "commonality" between M51 and the civlian programs, through herakles' contributions. But remember there are also french players like snecma who won't like giving up Vulcain 2 production.

If they still insist on using solids, I'm still shocked that they don't go for the Atlas V approach, with a varying amount of smaller solid boosters surrounding a slimmer cryogenic core derived from Ariane 5.

You find the answer in this thread.

The three solid first stage has been shown in a more practical side-by-side arrangement in other drawings.

How do you know its more "practical"? 

[R7]

To my knowledge M51 (french SLBM) is being built by Herakles, which also manufactures the nozzle for Vega/EAP and stage seperation for Vega.

Good info, thanks. EADS pages speak of itself as "prime contractor", apparently Safran Herakles is subcontractor. Still, same pattern.

http://www.herakles.com/strategique/m45/?lang=en
http://www.herakles.com/espace/propulsion/?lang=en
http://www.astrium.eads.net/en/programme/m-51.html

[Patchouli]

No, they already have the CBC equivalent - the current Ariane 5 core - it can be used as a starting point. Now it would never be able to take off without solids, but at least you could replace the Ariane 5 solids with 4-8 smaller solids to fine-tune the performance. Think of it as a hybrid between Ariane 5 and Atlas V.

They might need a higher thrust first stage engine then Vulcain.
Could a RS-68 be substituted and the tanks stretched to make them closer to a Delta CBC?

Though as is the H155 might make a good first stage with no SRBs and the RS-68.

[mmeijeri]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

[Patchouli]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

It is a regen engine so there should be no problems with clustering them.

[edkyle99]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

Exactly, and this was one of the Ariane 6 design alternatives (two Vulcain engine core with monolithic solid strap-on boosters), but it lost out to the PPH options.

 - Ed Kyle

[Lars_J]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

It is a regen engine so there should be no problems with clustering them.

How about an Ariane 9 with 9 Vulcain engines in a tic-tac-toe arrangement. Sounds familiar. 

[R7]

How about an Ariane 9 with 9 Vulcain engines in a tic-tac-toe arrangement. Sounds familiar. 

Rumor has it that setup is no longer fashionable

How about 4 Vulcains and 8 big strap-ons, we could call it Le Super-Énergie Vulcain !

[spacediver]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

Exactly, and this was one of the Ariane 6 design alternatives (two Vulcain engine core with monolithic solid strap-on boosters), but it lost out to the PPH options.

 - Ed Kyle

Exactly this was the problem.
They investigated only concepts with strap-on-boosters. But strap-on-boosters are expensive! Really expensive! You can kill every concept by adding boosters.
Adding a third Vulcain to the core and throw out the boosters entirely, as we did last year in the NELS study, would probably have resulted in another Ariane 6 baseline concept.
But concepts without boosters were never taken into account by CNES.

Spacediver

[spacediver]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

It is a regen engine so there should be no problems with clustering them.

How about an Ariane 9 with 9 Vulcain engines in a tic-tac-toe arrangement. Sounds familiar. 

Maybe good for a manned lunar mission...
Total overkill for the required Ariane-6 performance.
Probably more than 50 tons to LEO!
And a core diameter of at least 9m!
Would be a nice little beast but without a market...

Spacediver

[woods170]

They might need a higher thrust first stage engine then Vulcain.

Or more than one Vulcain.

Exactly, and this was one of the Ariane 6 design alternatives (two Vulcain engine core with monolithic solid strap-on boosters), but it lost out to the PPH options.

 - Ed Kyle

Exactly this was the problem.
They investigated only concepts with strap-on-boosters. But strap-on-boosters are expensive! Really expensive! You can kill every concept by adding boosters.
Adding a third Vulcain to the core and throw out the boosters entirely, as we did last year in the NELS study, would probably have resulted in another Ariane 6 baseline concept.
But concepts without boosters were never taken into account by CNES.

Spacediver

Looking into the history of Ariane it appears to me that strap-on boosters were a very important reason (along with the three versions of the H10 third stage) why Ariane-4 was such a versatile and succesfull launch vehicle. It could launch payloads thru a very wide mass-range, thanks - in part - to the strap-on boosters. And them being expensive did not seem to scare the customers away.

[baldusi]

Looking into the history of Ariane it appears to me that strap-on boosters were a very important reason (along with the three versions of the H10 third stage) why Ariane-4 was such a versatile and succesfull launch vehicle. It could launch payloads thru a very wide mass-range, thanks - in part - to the strap-on boosters. And them being expensive did not seem to scare the customers away.

You have to put it in the historical context. What was the competition? What were the trading limitations? What was the competition reliability, availability and price?
But in any case, the big issue is not even the now, but the next decade. Boosters allow for very fine performance steps. Yet, the PPH concept seems to have very coarse performance steps. Specially if they are trying to evolve the Vega to a P135+H, basically merging the rocket families.
The boosters decision is this:
No boosters: Overall cheaper at same performance, but coarser performance points.
Boosters: Overall cheaper at same performance, but finer performance points.
What this means is that if you have just two configurations, let's say P135+P135+H 3tonnes to GTO or 3 x P135+P135+H 7tonnes to GTO (it's an example, not actual numbers). And let's assume that the heavy costs twice as the single. Thus, you might have a lower price at 2 to 3tonnes and 5.5tonnes to 7 tonnes. But a 4tonnes satellite would have to pay twice the cost of a 3tonnes. But if you had a boosted architecture, you might be 15% more expensive in the 2 to 3 and 5.5 to 7, but between 3.1 and 4.5 you'd be significantly cheaper.
That's the real tradeoff of the boosted architecture. As it's now, GTO satellites are made in three groups, less than 3.5, 3.5 to 5 and 5+, with each group having, basically, a 1/3 of the market (in payloads, obviously in revenues is not the same). Since you'd be be pricing yourself out of the middle segment of the market, you'd also be resigning about 30% of your potential revenue. For a company that currently has 50% of the market, that's a lot.
But, you might also argue that in the next decade some new contestants will enter the market and that 50% will be impossible to keep. And if you make use of a boosted architecture you'll end up with a competitive price just on the central 1/3 of the market (because some competitors will not use boosted architectures). Thus, you'll lose even more market share.
That's the sort of economic analysis that is made about this issues (albeit at a much more sophisticated level).

[woods170]

Looking into the history of Ariane it appears to me that strap-on boosters were a very important reason (along with the three versions of the H10 third stage) why Ariane-4 was such a versatile and succesfull launch vehicle. It could launch payloads thru a very wide mass-range, thanks - in part - to the strap-on boosters. And them being expensive did not seem to scare the customers away.

You have to put it in the historical context. What was the competition? What were the trading limitations? What was the competition reliability, availability and price?
But in any case, the big issue is not even the now, but the next decade. Boosters allow for very fine performance steps. Yet, the PPH concept seems to have very coarse performance steps. Specially if they are trying to evolve the Vega to a P135+H, basically merging the rocket families.
The boosters decision is this:
No boosters: Overall cheaper at same performance, but coarser performance points.
Boosters: Overall cheaper at same performance, but finer performance points.
What this means is that if you have just two configurations, let's say P135+P135+H 3tonnes to GTO or 3 x P135+P135+H 7tonnes to GTO (it's an example, not actual numbers). And let's assume that the heavy costs twice as the single. Thus, you might have a lower price at 2 to 3tonnes and 5.5tonnes to 7 tonnes. But a 4tonnes satellite would have to pay twice the cost of a 3tonnes. But if you had a boosted architecture, you might be 15% more expensive in the 2 to 3 and 5.5 to 7, but between 3.1 and 4.5 you'd be significantly cheaper.
That's the real tradeoff of the boosted architecture. As it's now, GTO satellites are made in three groups, less than 3.5, 3.5 to 5 and 5+, with each group having, basically, a 1/3 of the market (in payloads, obviously in revenues is not the same). Since you'd be be pricing yourself out of the middle segment of the market, you'd also be resigning about 30% of your potential revenue. For a company that currently has 50% of the market, that's a lot.
But, you might also argue that in the next decade some new contestants will enter the market and that 50% will be impossible to keep. And if you make use of a boosted architecture you'll end up with a competitive price just on the central 1/3 of the market (because some competitors will not use boosted architectures). Thus, you'll lose even more market share.
That's the sort of economic analysis that is made about this issues (albeit at a much more sophisticated level).

Note that your entire argument rests on assumptions with regards to the final configurations and performances of the Ariane 6 vehicle.

As long as this vehicle is still being developed, and hard (as in: set in concrete) config and performance figures don't appear, the entire discussion about Arianespace losing or gaining market-share is moot.
Also, this vehicle does not start flying until 2022. Who knows how GTO satellites are categorized by then. They just might have switched to ion drives by then mostly, drastically reducing their weight. Heck, with that possibility in mind I would even see Ariane 6 performing dual launches.. 
But, let's not get into that discussion...

[Notaris]

By the way when we talk about solids, maybe it would make sense to make them reusable. After all they're stable enough such that you only have to attach a parachute to it and let them drop in the ocean.

Always had the idea, that reusable solids are same expensive as new solids...

Sorry for digging out old comments of this thread. If I remember right the following two points are true:

a) The dimensioning load case for the shuttle boosters were reentry, thus reusability had a performance impact beyond the mass penalty of the recovery system

b) Main reason for choosing reusable shuttle boosters was that the forecasted production capacity could not keep up with the forecasted STS flight rate (which obviously was never reached by far!)

[spacediver]

Looking into the history of Ariane it appears to me that strap-on boosters were a very important reason (along with the three versions of the H10 third stage) why Ariane-4 was such a versatile and succesfull launch vehicle. It could launch payloads thru a very wide mass-range, thanks - in part - to the strap-on boosters. And them being expensive did not seem to scare the customers away.

When the Ariane-program started in the early 70's, satellites were in the class of 1-1,5 tons to GTO, and a commercial satellite market not even existed. When the marked evolved, the US had the launcher gap after Challenger and satellite masses increased, it was a logical step to add booster to the existing launcher to increase payload mass without the need of a total new launch vehicle design.

Now the situation is completely different. We have competition on the commercial market and cost are the most important issue.

To add boosters to a "clean sheet" launcher concept can only be justified by allowing adaptation to different payload mass requirements.
This is where payload manifests and forecasts come into play.

For the NELS study we had two GTO payload requirements: 3,5t and 6,5t.
We investigated different payload forecasts from different organizations (ESA, CNES, DLR etc..) and came to the conclusion that we have about 80% of all launches for the large payload segment (3,5t - 6,5t) and only 20% for payloads below 3,5t.
In this case it is logical to optimize the launcher for the heavy payload class and accept some cost penalty for the small payload missions. We therefore proposed a HH-concept with three sea level optimized Vulcain engines in the first stage for the 6,5t missions. Upper stage with one Vinci.
For the small payloads we would have used exactly the same launcher but installed only two engines to the first stage. For launch, the first stage would only be filled up to 65% of its fuel capacity. This would save only the cost of one Vulcain but for one or two launches a year it would not justify another production line for a smaller first stage.
If we would optimize the launcher for the small payloads and add boosters for the large ones, we would have a tremendous cost penalty for each of the 80% of large payload launches.   

If the payload manifest would be the other way around (20% large and 80% small) then the booster version would probably be the more attractive one.

Now comes the problem with CNES: they are an institutional customer for Ariane, and institutional payloads are normally the smaller ones! So CNES is interrested in an optimized launcher for their own payloads and does not care about the competitiveness of the new launcher in the commercial GTO market.

That is why CNES never took launcher concepts into account that are not using strap-on-boosters, except for the Multi-P.

Spacediver

[Oli]

@spacediver

You once said 70m/launch is not realistic. You have any idea why the keep emphasizing that price point so much?

[Notaris]

@spacediver

You once said 70m/launch is not realistic. You have any idea why the keep emphasizing that price point so much?

Because, depending on market price for launches (i.e. income for performing commercial launches), Ariane 6 would risk to require more governmental support than Ariane 5 - killing the underlying argument for Ariane 6!

[pippin]

Looking into the history of Ariane it appears to me that strap-on boosters were a very important reason (along with the three versions of the H10 third stage) why Ariane-4 was such a versatile and succesfull launch vehicle. It could launch payloads thru a very wide mass-range, thanks - in part - to the strap-on boosters. And them being expensive did not seem to scare the customers away.

But did that really make a lot of sense? You carry all the cost for the different variants in your program while, at least later in the program, the were mostly flying the L variants. I would not be surprised if the overall program costs could have been reduced by doing away with, for example, the solid boosters (after all the liquid ones also shared the engines with the main stage).
And ballast steel isn't really that expensive so there is rarely ever a reason to _exactly_ match a payload mass with a capability.

Ariane always had a lot of aspects to the program that were in the "for the fun of it", "to develop some capability" or "to keep some partner happy" department.
And you know what I think about the whole Ariane 6 program in that respect....

[deltaV]

And ballast steel isn't really that expensive so there is rarely ever a reason to _exactly_ match a payload mass with a capability.

I hereby nominate that sentence for understatement of the day. Enough steel ballast to use an entire Ariane 5's GTO capacity costs around $10k. Even in Elon's dreamworld where most of the cost of a rocket launch goes to propellant that's still a small fraction of the cost of the launch!

[quanthasaquality]

Exactly this was the problem.
They investigated only concepts with strap-on-boosters. But strap-on-boosters are expensive! Really expensive! You can kill every concept by adding boosters.
Adding a third Vulcain to the core and throw out the boosters entirely, as we did last year in the NELS study, would probably have resulted in another Ariane 6 baseline concept.
But concepts without boosters were never taken into account by CNES.

Spacediver

Solid strap ons seem to work on cost in America for the EELVs. The Atlas V 501 can put 10 tons to LEO, and the 551 can put 20 tons to LEO. In the USA, liquid cores get the expensive bureaucratic treatment to ensure reliability. The solids don't need as much expensive oversight to ensure reliability.

With your logic, a larger Delta IV, without SRBs, complete with ablative nose cone, would be cheap to GTO.