My primary complaint about the published plans for the ESA
next generation launcher and/or Ariane 6 was that the liquid fueled
version was to use a
single new expensive staged-combustion engine at
about twice the thrust of the Vulcain.
I was therefore pleased to see that there is now being considered a
version that will use two engines on the core:
CNES, ASI Favor Solid-Rocket Design For Ariane 6.
By Amy Svitak.
Source: Aviation Week & Space Technology.
October 15, 2012.
Amy Svitak Naples, Italy, and Paris.
Bonnal says CNES is preparing wind-tunnel tests to adjust the margin
policy, and pressure oscillation has been assessed for different
flight phases.
Similar to the P1B, the all-liquid H2C would use up to six strap-on
boosters to carry as much as 8,400 kg to GTO. Twin main engines,
capable of 150 tons of vacuum thrust derived from the Ariane 5's
Snecma-built Vulcain 2, would comprise the H165 first stage, which
would be topped by a 31-ton cryogenic upper stage, he says.
http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_10_15_2012_p26-505016.xml&p=3
However, it seems to be the nature of governmental space agencies to
always want to go grandiose, like NASA. But instead of incurring the cost
of increasing the thrust of the Vulcain 2, why not use the same ones,
use a smaller upper stage (31 tons really??) and go with the smaller
Ariane 5 "G" version of the core stage?
As I discussed before, judging by the Japanese example with
the H-II rocket of adding on a second cryogenic engine, this
modification of the Ariane 5 core to use two Vulcains probably can be
done in the $200 million range. Then there really is no need to
continue talking about billion dollar development programs for the
Ariane 6.
Indeed with the recent ESA decision to engage in the development of
the Ariane 5 ME, this modification to the Ariane 5 core to use two
Vulcains is so comparitively low cost it could be done at the same
time as the Ariane 5 ME development. That is, you could have both
the Ariane 5 ME and the Ariane 6 in the same time frame.
Another point, again as I discussed before, the most
important result of following this approach is that it would result in
a manned capable launcher in a short time frame. Even if you are
skeptical of the SSTO version, just using the prior, small, ca. 10mT
gross mass upper stages, of the earlier Ariane versions,
you could have your manned launcher without the solid
side boosters. This key advantage I still haven't seen discussed but
obviously it would a great benefit in producing support among the
European public and the politicians who hold the ESA purse strings.
Bob Clark
Note: the attached image did not appear in the AV Week article, at least it
doesn't in the current version online. I found it after a web search. It does
show two engines on the liquid fueled version of the Ariane 6 core.