Delta IV Out as Potential X-37 Launcher?

On 22 Aug 2003 22:03:19 -0700, (ed kyle) wrote:

I should have said that Arianespace has now abandoned the
multiple configuration strap-on booster concept. The Ariane 5
strap-on boosters are a fixed part of the base vehicle design.
There are no other Ariane 5 variants that use different levels
of first stage thrust augmentation via different combinations
of strap-on boosters.

True, but at least Delta IV and Atlas 5 can and have launched
meaningful payloads without any strap-ons. Ariane 5 can't get off the
pad without them.

Ariane 4, on the other hand, used variable strap-on geometry
from the start, resulting in at least six possible vehicle
configurations that I can recall. Clearly, Arianespace decided
to simplify by reducing vehicle variants with Ariane 5.

Eh... that's playing a little loose with history by starting your
Ariane count at Ariane 4 instead of Ariane 1. I see no particular
difference in the Ariane 1-4 family's evolution of strap-on booster
configurations and Delta 1-3 family's use of them.

Brian

ed kyle wrote:

Boeing's approach, where part of the
vehicle is integrated horizontally and part vertically, with
the payload added vertically, does seem to have failed by
combining the worst features of both horizontal and vertical
methods. Another design by the committee that gave us the
X-32 "Monica" and the "Sonic Cruiser"?

No, the Monica and the Sonic Cruiser were Boeing-Seattle creations.
Delta IV was designed in Huntington Beach.

As for the meat of the subthread, I have to say that as much as I like
Delta IV, the 8 hours of on-pad time for the Atlas V is damned impressive.

Mike

-----
Michael Kent Apple II Forever!!
St. Peters, MO

In article ,
Murray Anderson wrote:
Both Delta II and Atlas II are modular designs...

Not really, not in any strong sense. The only thing that was really
modular about Delta II, at least until the IIH appeared, was the option of
leaving off a few of the strap-ons (which was always more of a marketing
gimmick than a way to really reduce the cost a whole lot -- the things
cost only about $1M each).

Similarly, the modularity on Atlas II and III is pretty weak -- just an
option to add a couple of small strap-ons -- compared to Angara or even
Ariane 4.

Their EELV replacements are modular designs.

Yes and no. Most of the real modularity -- the option of using more than
one core stage -- is steadily receding into the never-never land of
hypothetical configurations which see little or no actual use.

However, it is true that they are vigorously adding strap-on options,
because their core stages are too small and the multi-core configurations
are too expensive. The real question is whether the core-only versions
are going to see any actual use. (Nobody has flown a bare Delta II core
in a long time -- I'm not sure it's even possible any more -- so it
doesn't really count as a modular option.)
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

"Murray Anderson" wrote in message ...
"ed kyle" wrote in message
om...
Damon Hill wrote in message
. 132...
(ed kyle) wrote in
om:

I wonder if it might not be cheaper to simply build a single,
more powerful rocket and launch it under-capacity much of the
time. That is consistent with Proton, Sea-Launch Zenit, and
now Ariane 5.

Simplified modularity is the order of the day; one size fits all
doesn't, really. Check out the approach that Angara is taking. The
Angara can cover a very wide range of payloads, which Ariane
5 can't.

I've seen many Angara concepts on paper over the years, but
none have flown. The modular approach has been tried before,
and it has failed every time.


Both Delta II and Atlas II are modular designs, and Delta II is a
continuation of a family of modular designs. Their EELV replacements are
modular designs. Ariane 4 was a modular design. This may be a bad idea, but
the statistics on reliability don't give any support. Arianespace must be
wishing they had a new launcher as reliable as the old.
Khrunichev is in good company with its modular design.


Delta II, Atlas II, and Ariane 4 are/were not modular the way
that Angara is planned to be, with a first stage built up as
a cluster of identical thrust units. This type of modularity
has failed before when attempted by Conestoga, OTRAG, and VLS.
It may work for Angara and/or Delta IVH, but the real problem
is that it makes the bigger Angara 5 vehicle more complicated
than necessary. An Angara 1, with just one boost unit, will
probably never fly because it is too small. Angara 3 will
rarely fly because it too is small. Of this year's 15 GTO/GSO
satellites, only 4 were small enough for Angara 3 (and two of
these were carried in dual Ariane 5 launches). Most of these
satellites are Angara 5 class, so why not build a single-diameter
Angara 5 first stage?

- Ed Kyle

"Henry Spencer" wrote in message
...
In article ,
Murray Anderson wrote:
Both Delta II and Atlas II are modular designs...

Not really, not in any strong sense. The only thing that was really
modular about Delta II, at least until the IIH appeared, was the option of
leaving off a few of the strap-ons (which was always more of a marketing
gimmick than a way to really reduce the cost a whole lot -- the things
cost only about $1M each).

Similarly, the modularity on Atlas II and III is pretty weak -- just an
option to add a couple of small strap-ons -- compared to Angara or even
Ariane 4.

Atlas III isn't a modular design in the sense we're discussing, since it
doesn't have strap-on boosters as an option. The only options are related to
the Centaur. Atlas IIAS has 4 solid strap-ons, two ignited at ground level,
two in the air. Definitely modular.

Their EELV replacements are modular designs.

Yes and no. Most of the real modularity -- the option of using more than
one core stage -- is steadily receding into the never-never land of
hypothetical configurations which see little or no actual use.

Atlas V 401 has a GTO payload of 4.9 tons, which makes it a realistic option
in many cases. It's true that Delta IV Medium is a little small. It appears
to be underpowered, about 1.15 g thrust at liftoff, which is supposed to be
low for LH2 rockets. They should have designed the RS-68 for higher thrust.

Murray Anderson
However, it is true that they are vigorously adding strap-on options,
because their core stages are too small and the multi-core configurations
are too expensive. The real question is whether the core-only versions
are going to see any actual use. (Nobody has flown a bare Delta II core
in a long time -- I'm not sure it's even possible any more -- so it
doesn't really count as a modular option.)
--
MOST launched 1015 EDT 30 June, separated 1046, | Henry Spencer
first ground-station pass 1651, all nominal! |

"ed kyle" wrote in message
om...
"Murray Anderson" wrote in message
...
"ed kyle" wrote in message
om...
Damon Hill wrote in message
. 132...
(ed kyle) wrote in
om:

I wonder if it might not be cheaper to simply build a single,
more powerful rocket and launch it under-capacity much of the
time. That is consistent with Proton, Sea-Launch Zenit, and
now Ariane 5.

Simplified modularity is the order of the day; one size fits all
doesn't, really. Check out the approach that Angara is taking. The
Angara can cover a very wide range of payloads, which Ariane
5 can't.

I've seen many Angara concepts on paper over the years, but
none have flown. The modular approach has been tried before,
and it has failed every time.


Both Delta II and Atlas II are modular designs, and Delta II is a
continuation of a family of modular designs. Their EELV replacements are
modular designs. Ariane 4 was a modular design. This may be a bad idea,
but
the statistics on reliability don't give any support. Arianespace must
be
wishing they had a new launcher as reliable as the old.
Khrunichev is in good company with its modular design.


Delta II, Atlas II, and Ariane 4 are/were not modular the way
that Angara is planned to be, with a first stage built up as
a cluster of identical thrust units. This type of modularity
has failed before when attempted by Conestoga, OTRAG, and VLS.

But it's not any different in concept from using solid strap-ons, or liquid
strap-ons like Ariane 4 (some versions). The fact that the projects failed
has nothing to do with the identical nature of members of the cluster.

It may work for Angara and/or Delta IVH, but the real problem
is that it makes the bigger Angara 5 vehicle more complicated
than necessary. An Angara 1, with just one boost unit, will
probably never fly because it is too small. Angara 3 will
rarely fly because it too is small. Of this year's 15 GTO/GSO
satellites, only 4 were small enough for Angara 3 (and two of
these were carried in dual Ariane 5 launches). Most of these
satellites are Angara 5 class, so why not build a single-diameter
Angara 5 first stage?

- Ed Kyle

The Angara 1 is for LEO satellites, and possibly the Russian military needs
it. Your point about the core stage being too small may be valid in the
commercial market, but it isn't a purely commercial vehicle.

Murray Anderson

"Dholmes" wrote in message
...

Atlas V 401 has a GTO payload of 4.9 tons, which makes it a realistic
option
in many cases. It's true that Delta IV Medium is a little small. It
appears
to be underpowered, about 1.15 g thrust at liftoff, which is supposed to
be
low for LH2 rockets. They should have designed the RS-68 for higher
thrust.


While I agree that the R-68 should have been built bigger the thrust ratio
is very misleading.

The Delta 4 medium does not launch at lower gravity then Atlas 5 401 when
launching to GTO and beyond.
It is only when launching lower then GTO that it does.

I'm not quite sure what you mean here, but 1.15 is the figure given in the
Delta 4 manual.

The first stage of the Delta would do about 1.35 as a stand alone while
the
Atlas 4 would do about 1.25.

I get 1.3 for the Delta and 1.26 for the Atlas, but my figures for Delta are
just estimates from acceleration and thrust data, so you could be right
about it.

The reason they are close is not because of the first stage but the
second.
On the Delta 4 the second stage weights 51,000 lbs vs. 42,000 for an Atlas
5
while only having 75% of the trust.

The Centaur III on the Atlas V weighs about 51000 lbs. It's heavier than the
Atlas II Centaur.


When combined with a larger fuel tank on the fist stage and large solid
rocket boosters the Delta 4 is much more expandable then the Atlas 5.



Both are pretty expandable. E.g. Delta IV Heavy and Atlas V 551.

Murray Anderson

(ed kyle) writes:
Most of these
satellites are Angara 5 class, so why not build a single-diameter
Angara 5 first stage?

Transportation limitations. Specifically, the ability for the modules
to be shipped by rail.

Jeff
--
Remove "no" and "spam" from email address to reply.
If it says "This is not spam!", it's surely a lie.