Quote from: envy887 on 06/04/2018 01:48 pmIf they want to RTLS with the booster after GTO missions it's either that or a much larger vehicle to make up for the efficiency difference. And full reuse will be very difficult with a medium lift vehicle and GG engines. Since Ariane isn't doing super-heavy lift as far as I can tell, they are going to be years behind the competition if they don't start on staged combustion. ???Reusability, full or partial, is perfectly doable with GG. Since when have SpaceX fans become ISP fetishists?As for "behind the competition". Lot's of people here obviously don't get the nature of the Ariane program. It has never been about technological leadership. It's irrelevant if they fall behind as long as the government is willing to fund the next iteration.As a taxpayer I don't have a problem with that. I don't want a government-funded state-of-the-art engine program, because it would be bloody expensive. If the commercial market becomes big enough, ArianeGroup can play leader on their own. Otherwise they have to live with being followers.
If they want to RTLS with the booster after GTO missions it's either that or a much larger vehicle to make up for the efficiency difference. And full reuse will be very difficult with a medium lift vehicle and GG engines. Since Ariane isn't doing super-heavy lift as far as I can tell, they are going to be years behind the competition if they don't start on staged combustion.
Quote from: ChrisWilson68 on 06/04/2018 06:59 amAgain, failing to appreciate the disruption that is happening, even as it is happening. Thinking there will somehow magically be a market for the far more expensive solution.You forget: SpaceX is disrupting the launch market because they are launching unicorns into space. Arianespace is just launching ponies. Silly Arianespace. don't take it too bad, I'm not in denial nor an Arianespace amazing people, just a little annoyed and irritated by the overal tone "SpaceX is turning led into gold" you know what I mean.
Again, failing to appreciate the disruption that is happening, even as it is happening. Thinking there will somehow magically be a market for the far more expensive solution.
I'm sure 20 years ago people at Kodak were annoyed and irritated by the tone of people talking about these new digital cameras and how digital cameras were turning lead into gold.Being annoyed doesn't mean a major technology change isn't real.
Quote from: Oli on 06/04/2018 02:50 pmQuote from: envy887 on 06/04/2018 01:48 pmIf they want to RTLS with the booster after GTO missions it's either that or a much larger vehicle to make up for the efficiency difference. And full reuse will be very difficult with a medium lift vehicle and GG engines. Since Ariane isn't doing super-heavy lift as far as I can tell, they are going to be years behind the competition if they don't start on staged combustion. Reusability, full or partial, is perfectly doable with GG. Since when have SpaceX fans become ISP fetishists?As for "behind the competition". Lot's of people here obviously don't get the nature of the Ariane program. It has never been about technological leadership. It's irrelevant if they fall behind as long as the government is willing to fund the next iteration.As a taxpayer I don't have a problem with that. I don't want a government-funded state-of-the-art engine program, because it would be bloody expensive. If the commercial market becomes big enough, ArianeGroup can play leader on their own. Otherwise they have to live with being followers.Being a follower can be a fine strategy. But you have to actually follow. If Europe want to follow, then need to be working on staged combustion now.Otherwise, they're failing to follow, they're being left behind.
Quote from: envy887 on 06/04/2018 01:48 pmIf they want to RTLS with the booster after GTO missions it's either that or a much larger vehicle to make up for the efficiency difference. And full reuse will be very difficult with a medium lift vehicle and GG engines. Since Ariane isn't doing super-heavy lift as far as I can tell, they are going to be years behind the competition if they don't start on staged combustion. Reusability, full or partial, is perfectly doable with GG. Since when have SpaceX fans become ISP fetishists?As for "behind the competition". Lot's of people here obviously don't get the nature of the Ariane program. It has never been about technological leadership. It's irrelevant if they fall behind as long as the government is willing to fund the next iteration.As a taxpayer I don't have a problem with that. I don't want a government-funded state-of-the-art engine program, because it would be bloody expensive. If the commercial market becomes big enough, ArianeGroup can play leader on their own. Otherwise they have to live with being followers.
Quote from: ChrisWilson68 on 06/05/2018 09:58 pmQuote from: Oli on 06/04/2018 02:50 pmQuote from: envy887 on 06/04/2018 01:48 pmIf they want to RTLS with the booster after GTO missions it's either that or a much larger vehicle to make up for the efficiency difference. And full reuse will be very difficult with a medium lift vehicle and GG engines. Since Ariane isn't doing super-heavy lift as far as I can tell, they are going to be years behind the competition if they don't start on staged combustion. Reusability, full or partial, is perfectly doable with GG. Since when have SpaceX fans become ISP fetishists?As for "behind the competition". Lot's of people here obviously don't get the nature of the Ariane program. It has never been about technological leadership. It's irrelevant if they fall behind as long as the government is willing to fund the next iteration.As a taxpayer I don't have a problem with that. I don't want a government-funded state-of-the-art engine program, because it would be bloody expensive. If the commercial market becomes big enough, ArianeGroup can play leader on their own. Otherwise they have to live with being followers.Being a follower can be a fine strategy. But you have to actually follow. If Europe want to follow, then need to be working on staged combustion now.Otherwise, they're failing to follow, they're being left behind.BE-4 is a low performance SC engine with a chamber pressure of 13.4MPa (for comparison Vulcain 2.1 has a chamber pressure of 12.1MPa). Is Blue Origin falling behind as well? By your definition SpaceX was falling behind when it went for a kerolox GG, given high performance engines like RD-180 and RS-25 were already in use for decades.Besides, work on SC has already been done in Europe a decade ago. If SpaceX didn't appear Ariane 6 might very well have had a SC engine, at least that was the favored technical configuration back then. Then cost-consciousness set in.
I'm sure 20 years ago people at Kodak were annoyed and irritated by the tone of people talking about these new digital cameras and how digital cameras were turning lead into gold.
Quote from: Oli on 06/06/2018 09:25 amQuote from: ChrisWilson68 on 06/05/2018 09:58 pmQuote from: Oli on 06/04/2018 02:50 pmQuote from: envy887 on 06/04/2018 01:48 pmIf they want to RTLS with the booster after GTO missions it's either that or a much larger vehicle to make up for the efficiency difference. And full reuse will be very difficult with a medium lift vehicle and GG engines. Since Ariane isn't doing super-heavy lift as far as I can tell, they are going to be years behind the competition if they don't start on staged combustion. Reusability, full or partial, is perfectly doable with GG. Since when have SpaceX fans become ISP fetishists?As for "behind the competition". Lot's of people here obviously don't get the nature of the Ariane program. It has never been about technological leadership. It's irrelevant if they fall behind as long as the government is willing to fund the next iteration.As a taxpayer I don't have a problem with that. I don't want a government-funded state-of-the-art engine program, because it would be bloody expensive. If the commercial market becomes big enough, ArianeGroup can play leader on their own. Otherwise they have to live with being followers.Being a follower can be a fine strategy. But you have to actually follow. If Europe want to follow, then need to be working on staged combustion now.Otherwise, they're failing to follow, they're being left behind.BE-4 is a low performance SC engine with a chamber pressure of 13.4MPa (for comparison Vulcain 2.1 has a chamber pressure of 12.1MPa). Is Blue Origin falling behind as well? By your definition SpaceX was falling behind when it went for a kerolox GG, given high performance engines like RD-180 and RS-25 were already in use for decades.Besides, work on SC has already been done in Europe a decade ago. If SpaceX didn't appear Ariane 6 might very well have had a SC engine, at least that was the favored technical configuration back then. Then cost-consciousness set in.Merlin was innovative in ways beside cycle and pressure: its cost, thrust/weight ratio, reusability, and deep throttling were all state of the art. Prometheus is an attempt to copy that state-of-art, but it is also a sign of missing another coming disruption.
Quote from: ChrisWilson68 on 06/05/2018 11:02 pmI'm sure 20 years ago people at Kodak were annoyed and irritated by the tone of people talking about these new digital cameras and how digital cameras were turning lead into gold.from wiki,Steven Sasson, an engineer at Eastman Kodak, invented and built the first self-contained electronic camera that used a charge-coupled device image sensor in 1975.
Quote from: envy887 on 06/06/2018 01:09 pmMerlin was innovative in ways beside cycle and pressure: its cost, thrust/weight ratio, reusability, and deep throttling were all state of the art. Prometheus is an attempt to copy that state-of-art, but it is also a sign of missing another coming disruption.How about the relationship between Merlin and FASTRAC ?
Merlin was innovative in ways beside cycle and pressure: its cost, thrust/weight ratio, reusability, and deep throttling were all state of the art. Prometheus is an attempt to copy that state-of-art, but it is also a sign of missing another coming disruption.
What I exactly meant: SpaceX used Fastrac (and Bantam) technologies for Merlin. Even if there is no DIRECT legacy between the two, it certainly helped... By the way, FASTRAC was for X-34 (AFAIK) which is not that dissimilar to a Falcon 9 in its goals - a reusable first stage, low cost. How about that.
FASTRAC had an ablative chamber and nozzle, so while it was cheap I don't think it would have been very practical to reuse. It also didn't feature restart, deep throttle, or high TWR. So it wasn't anywhere near state of the art besides on cost.
None of which is particularly relevant to Prometheus. Prometheus, if it works as intended, will be a good engine. But it will be outdated in an era where engines have to be BOTH high performance and low cost. That's what we're looking at in 15 years.
It's not so much about what is best, but rather what you can get.With the presentation the situation in Europe is much better than most here thought a few months ago.I don't like the recovery concept too much. Why expend the low and slow boosters while recovering the higher and faster central core?I'd flip the concept. Recover boosters, convert the central stage back to a A5/A6 like sustainer stage, and expend it. The horror!The boosters are small and plentiful enough. If you loose one on landing? No big deal.More importantly Prometheus reuse is limiting. Say 4 boosters, 3 engines each, 4 flights total (1 as landing engine). That means you can dispose of 4 engines each flight. Should be enough for a sustainer stage. Staging really high again means that you can keep the existing hydrogen upper stage and don't need to invent a new one. The additional ISP there should really help.
Quote from: Archibald on 06/06/2018 04:59 pmQuote from: envy887 on 06/06/2018 01:09 pmMerlin was innovative in ways beside cycle and pressure: its cost, thrust/weight ratio, reusability, and deep throttling were all state of the art. Prometheus is an attempt to copy that state-of-art, but it is also a sign of missing another coming disruption.How about the relationship between Merlin and FASTRAC ?Do you think FASTRAC shared any of those attributes? (cost, thrust/weight ratio, reusability, and deep throttling) It was a starting point for a design nothing more. If you know more, please educate us.
Quote from: Archibald on 06/05/2018 06:11 pmGimme a break. Please somebody translate what "GG" and "SC" mean. It would help. A Lot.GG is Gas Generator (Merlin, Vulcain, Vulcain2), SC is Staged Combustion (SSME, Raptor)Were you not aware of this?
Gimme a break. Please somebody translate what "GG" and "SC" mean. It would help. A Lot.
Ahh. So that's why Merlin 1a was ablative. I guess that's where the Barber Nicholl radial inflow turbo pump come from?
It also didn't feature restart, deep throttle, or high TWR.
How politically tenable is a design that doesn't use solids? Italy and Germany just swapped some production stuff so that all the solids work for Ariane are being done in Italy now. If they went to a design that didn't use solids, would Italy try to block it? Could they?As an idea to get around this issue and playing off your concern above about disposing of a costly center stage, how about large, reusable liquid engine boosters that are recovered and an expendable, air-lit solid center core? It gives up some on performance, but always recovers the high value LRE boosters and only tosses the relatively cheap solid case.
Quote from: deruch on 06/06/2018 11:08 pmHow politically tenable is a design that doesn't use solids? Italy and Germany just swapped some production stuff so that all the solids work for Ariane are being done in Italy now. If they went to a design that didn't use solids, would Italy try to block it? Could they?As an idea to get around this issue and playing off your concern above about disposing of a costly center stage, how about large, reusable liquid engine boosters that are recovered and an expendable, air-lit solid center core? It gives up some on performance, but always recovers the high value LRE boosters and only tosses the relatively cheap solid case. The solids are used by Vega and the French SLBM programme. So the French will probably complain, and since CNES (which is French) is normally the development lead for Ariane their concepts will normally have "Use a big solid" as part of their brief.
How politically tenable is a design that doesn't use solids? Italy and Germany just swapped some production stuff so that all the solids work for Ariane are being done in Italy now. If they went to a design that didn't use solids, would Italy try to block it? Could they?
As an idea to get around this issue and playing off your concern above about disposing of a costly center stage, how about large, reusable liquid engine boosters that are recovered and an expendable, air-lit solid center core? It gives up some on performance, but always recovers the high value LRE boosters and only tosses the relatively cheap solid case.
Quote from: john smith 19 on 06/07/2018 06:09 amQuote from: deruch on 06/06/2018 11:08 pmHow politically tenable is a design that doesn't use solids? Italy and Germany just swapped some production stuff so that all the solids work for Ariane are being done in Italy now. If they went to a design that didn't use solids, would Italy try to block it? Could they?As an idea to get around this issue and playing off your concern above about disposing of a costly center stage, how about large, reusable liquid engine boosters that are recovered and an expendable, air-lit solid center core? It gives up some on performance, but always recovers the high value LRE boosters and only tosses the relatively cheap solid case. The solids are used by Vega and the French SLBM programme. So the French will probably complain, and since CNES (which is French) is normally the development lead for Ariane their concepts will normally have "Use a big solid" as part of their brief. not so sure about that. SLBM are considered a strategic asset hence the industrial base is similar. With or without Ariane, it will live as long as France have a nuclear arsenal. Just look at the Saint Nazaire shipyards: Italy wanted them but the French government stepped it and blocked the sale, because building huge ships = strategic capability. I agree with the second point - Ariane SRBs surely have an industrial lobby - mostly civilian, french and italian and mostly disconnected from SLMBs - quite similar to Utah / ATK in Congress. Just thinking about it, near Bordeaux is Saint Médard en Jalles and there is a pretty big solid propellant factory there. They actually fire spent M4 / 45 / M51 missiles just to destroy them. And they manufacture Ariane 5 SRBs there.