At first glance the drop of in payload from GTO 1500 m/s (11,000) to GEO (4,100 kg) seems harsh.
Some quick napkin-math:For standard commercial GTO missions Ariane 64 lifts 24% more mass than Atlas 551, while still providing a advantageous injection orbit to the customer (Δv GEO 1500 instead 1800 m/s).If both launchers head direct for GEO, then Ariane's advantage is reduced to 6%, despite A64 having a "head start" by launching from Kourou.Now GEO missions are (very) rare, but it's not like a lighter upper stage wouldn't help with GTO or MEO missions as well...
Quote from: calapine on 02/14/2017 07:38 pmSome quick napkin-math:For standard commercial GTO missions Ariane 64 lifts 24% more mass than Atlas 551, while still providing a advantageous injection orbit to the customer (Δv GEO 1500 instead 1800 m/s).If both launchers head direct for GEO, then Ariane's advantage is reduced to 6%, despite A64 having a "head start" by launching from Kourou.Now GEO missions are (very) rare, but it's not like a lighter upper stage wouldn't help with GTO or MEO missions as well...Ariane 6 is not about maximizing performance. It's about minimizing cost to build and launch it. That led to no significant re-design of the existing Vinci-propelled upper stage design, because it is not needed: GTO is by far the standard over GEO.
Quote from: woods170 on 02/15/2017 06:56 amQuote from: calapine on 02/14/2017 07:38 pmSome quick napkin-math:For standard commercial GTO missions Ariane 64 lifts 24% more mass than Atlas 551, while still providing a advantageous injection orbit to the customer (Δv GEO 1500 instead 1800 m/s).If both launchers head direct for GEO, then Ariane's advantage is reduced to 6%, despite A64 having a "head start" by launching from Kourou.Now GEO missions are (very) rare, but it's not like a lighter upper stage wouldn't help with GTO or MEO missions as well...Ariane 6 is not about maximizing performance. It's about minimizing cost to build and launch it. That led to no significant re-design of the existing Vinci-propelled upper stage design, because it is not needed: GTO is by far the standard over GEO.But evegy gram in their upper stage is exactly on gram less in their payload.A62 is now 5000 kg to GTO, A64 11000 kg to GTO.IF they have a 5500 kg satellite to GTO, 500 kg lighter upper stage would allow them to use A62 instead of A64, saving two SRB'sOr, if they have a 6300 kg satellite to GTO, 1300kg lighter upper stage would allow them to use A62 instead of A64, saving two SRB'sAnd AFAIK there are quite a lot of satellites in this size range.Only on LEO launches the upper stage weight is not a big waste. But LEO launches on A6 will be quite rare.
Quote from: hkultala on 02/15/2017 07:33 amQuote from: woods170 on 02/15/2017 06:56 amQuote from: calapine on 02/14/2017 07:38 pmSome quick napkin-math:For standard commercial GTO missions Ariane 64 lifts 24% more mass than Atlas 551, while still providing a advantageous injection orbit to the customer (Δv GEO 1500 instead 1800 m/s).If both launchers head direct for GEO, then Ariane's advantage is reduced to 6%, despite A64 having a "head start" by launching from Kourou.Now GEO missions are (very) rare, but it's not like a lighter upper stage wouldn't help with GTO or MEO missions as well...Ariane 6 is not about maximizing performance. It's about minimizing cost to build and launch it. That led to no significant re-design of the existing Vinci-propelled upper stage design, because it is not needed: GTO is by far the standard over GEO.But evegy gram in their upper stage is exactly on gram less in their payload.A62 is now 5000 kg to GTO, A64 11000 kg to GTO.IF they have a 5500 kg satellite to GTO, 500 kg lighter upper stage would allow them to use A62 instead of A64, saving two SRB'sOr, if they have a 6300 kg satellite to GTO, 1300kg lighter upper stage would allow them to use A62 instead of A64, saving two SRB'sAnd AFAIK there are quite a lot of satellites in this size range.Only on LEO launches the upper stage weight is not a big waste. But LEO launches on A6 will be quite rare.The current cryogenic upper stage on A5 ECA is also very much mass-inefficient. But that does not stop A5 from being the one of the most succesful commercial launchers today.Again: A6 is not about maximizing performance. It's about minimizing cost. And despite the hefty numbers for payload masses today, the general future trend is that mass of commercial payloads will go down.
That is why I suggested triple launch 3 30 million satellite launch beats 70 million in anybodies book provided the launcher is reliable .
Quote from: floss on 02/24/2017 05:27 pmThat is why I suggested triple launch 3 30 million satellite launch beats 70 million in anybodies book provided the launcher is reliable . The number of times there would be 3 ~3000 kg satellites needed to be launched and ready for the same launch window is so rare that developing & certifying a SYLTA (Système de Lancement Triple Ariane) isn't worth it.Aside from that, a triple launch would be a nightmare from an insurance point of view...
Quote from: calapine on 02/24/2017 08:52 pmQuote from: floss on 02/24/2017 05:27 pmThat is why I suggested triple launch 3 30 million satellite launch beats 70 million in anybodies book provided the launcher is reliable . The number of times there would be 3 ~3000 kg satellites needed to be launched and ready for the same launch window is so rare that developing & certifying a SYLTA (Système de Lancement Triple Ariane) isn't worth it.Aside from that, a triple launch would be a nightmare from an insurance point of view...I never said 3 3000 kg satellites I figure that Ariane 6 will grow fairly quickly after it is built just like Ariane 5 did at present Ariane 6 4 adds no new capability.
Well, we all know how these European projects work.... there has to be a next project so that more money can be spent and a mass-optimized upper stage is a really nice one because you can easily develop that without interrupting current operations...
Quote from: pippin on 02/15/2017 12:23 amWell, we all know how these European projects work.... there has to be a next project so that more money can be spent and a mass-optimized upper stage is a really nice one because you can easily develop that without interrupting current operations...I hpoe you are not an US citizen, else I would have to say: "SLS".
Quote from: calapine on 02/24/2017 08:52 pmQuote from: floss on 02/24/2017 05:27 pmThat is why I suggested triple launch 3 30 million satellite launch beats 70 million in anybodies book provided the launcher is reliable . The number of times there would be 3 ~3000 kg satellites needed to be launched and ready for the same launch window is so rare that developing & certifying a SYLTA (Système de Lancement Triple Ariane) isn't worth it.Aside from that, a triple launch would be a nightmare from an insurance point of view...Was not that the point of Cone eXpress with 75 million you can add a third satellite to Ariane 5 already seeing as the launch of a satellite is the most dangerous part of its life the more satellites on a reliable launcher the better .
Quote from: floss on 06/04/2017 04:55 pmQuote from: calapine on 02/24/2017 08:52 pmQuote from: floss on 02/24/2017 05:27 pmThat is why I suggested triple launch 3 30 million satellite launch beats 70 million in anybodies book provided the launcher is reliable . The number of times there would be 3 ~3000 kg satellites needed to be launched and ready for the same launch window is so rare that developing & certifying a SYLTA (Système de Lancement Triple Ariane) isn't worth it.Aside from that, a triple launch would be a nightmare from an insurance point of view...Was not that the point of Cone eXpress with 75 million you can add a third satellite to Ariane 5 already seeing as the launch of a satellite is the most dangerous part of its life the more satellites on a reliable launcher the better .Why bother bring that up? ConeXpress has been dead for a decade.
Quote from: woods170 on 06/05/2017 06:46 pmQuote from: floss on 06/04/2017 04:55 pmQuote from: calapine on 02/24/2017 08:52 pmQuote from: floss on 02/24/2017 05:27 pmThat is why I suggested triple launch 3 30 million satellite launch beats 70 million in anybodies book provided the launcher is reliable . The number of times there would be 3 ~3000 kg satellites needed to be launched and ready for the same launch window is so rare that developing & certifying a SYLTA (Système de Lancement Triple Ariane) isn't worth it.Aside from that, a triple launch would be a nightmare from an insurance point of view...Was not that the point of Cone eXpress with 75 million you can add a third satellite to Ariane 5 already seeing as the launch of a satellite is the most dangerous part of its life the more satellites on a reliable launcher the better .Why bother bring that up? ConeXpress has been dead for a decade.Dead or just waiting for an investor my point was that triple launch is nowhere near as costly as some people think .