 |
|
| Science Forum Index » Space Forum » Rocket design up in air, says Marshall chief |
|
Page 3 of 3 Goto page Previous 1, 2, 3 |
|
| Author |
Message |
| Henry Spencer |
 Posted: Sat Feb 19, 2005 1:33 pm |
|
|
|
Guest
|
In article <9ote11taevvputvpugppf9cutfu1v5bt02@4ax.com>,
Fred J. McCall <fmccall@earthlink.net> wrote:
[quote:78da0f17e7]:>Name a single man-rated solid fuel vehicle...
:The original Titan IIIC, which was built to carry Dyna-Soar. Mind you, it
:*did* have thrust termination for its SRBs, to give Dyna-Soar a clear
:chance to escape.
Paper rating.
[/quote:78da0f17e7]
They're all paper ratings. Nobody has ever demonstrated *by flight test*
that "man-rating" makes any real difference in reliability. (Some of the
specific design changes made to man-rate missiles probably do improve it,
but the process as a whole, when applied to a vehicle designed for manned
flight, no.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | henry@spsystems.net |
|
|
| Back to top |
|
|
|
| Ed Kyle |
| Posted: Sat Feb 19, 2005 7:29 pm |
|
|
|
Guest
|
Fred J. McCall wrote:
[quote:46dad82528]"Ed Kyle" <edkyle99@hotmail.com> wrote:
:Henry Spencer wrote:
:> In article <6p6b019hhp1qtip0qo9vo7c3svn2vmcldn@4ax.com>,
:> Fred J. McCall <fmccall@earthlink.net> wrote:
:> >Name a single man-rated solid fuel vehicle anywhere during the
:history
:> >of space, other than the STS with SRBs.
:
:> The original Titan IIIC, which was built to carry Dyna-Soar.
:
:Ariane 5, designed to launch the Hermes spaceplane.
Let's wait until they stop blowing up, shall we?
[/quote:46dad82528]
Right now, Ariane 5ECA is the world's most powerful,
successfully-flown rocket in production and flying.
The last Ariane 5 "blow up" happened in December 2002.
There have been seven consecutive successes since.
By the way, none of the four Ariane 5 mission failures
that have occurred (out of 21 flights) involved the
vehicle's solid rocket boosters. Two were outright
failures of liquid propulsion systems. Two were
flight control issues. All four failures would have
been survivable if a crew carrying system with an
escape system had been the payload.
[quote:46dad82528]Hermes spaceplane? Another paper vehicle.
[/quote:46dad82528]
It was well into development - and Ariane 5 *was*
developed to carry it. That is why Ariane 5 has
had to be so extensively upgraded to compete in the
comsat market. It was not optimized for that work
from the outset.
- Ed Kyle |
|
|
| Back to top |
|
|
|
| Henry Spencer |
| Posted: Sat Feb 19, 2005 8:10 pm |
|
|
|
Guest
|
In article <1108859388.723936.51460@o13g2000cwo.googlegroups.com>,
Ed Kyle <edkyle99@hotmail.com> wrote:
[quote:df2c064997]Hermes spaceplane? Another paper vehicle.
It was well into development - and Ariane 5 *was*
developed to carry it. That is why Ariane 5 has
had to be so extensively upgraded to compete in the
comsat market. It was not optimized for that work
from the outset.
[/quote:df2c064997]
It would have needed even more upgrading without Hermes. Hermes's main
influence on Ariane 5 is that Hermes kept requiring the rocket to be
*bigger*... and the upgrades are all pushing that still further. The
problem Ariane 5 has with being competitive in the comsat market is not
optimization for Hermes, but the rapid growth in high-end-comsat size
during Ariane 5's prolonged gestation.
Ariane 5 *was* always intended primarily as a comsat launcher, with Hermes
compatibility a secondary constraint... but the economic assumptions used
to assess competitiveness assumed two birds per launch, as used to be
common on Ariane 4. The main reason for building a new launcher was that
the comsats increasingly no longer fit in half an Ariane 4, and A4 wasn't
competitive with only a single payload. Alas, the guys writing the spec
underestimated the rate of growth and the time it would take to get a
replacement launcher going, and undersized Ariane 5, which now has the
same problem.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | henry@spsystems.net |
|
|
| Back to top |
|
|
|
| Rand Simberg |
| Posted: Sat Feb 19, 2005 10:33 pm |
|
|
|
Guest
|
On 20 Feb 2005 01:34:31 GMT, in a place far, far away,
gherbert@retro.com (George William Herbert) made the phosphor on my
monitor glow in such a way as to indicate that:
[quote:36c429a250]Given the alternatives, I'd rather have a launch vehicle I
can confidently monitor and which will deliver me acceptable
warning upon failure, and which has relatively benign escape
conditions upon abort, than a very reliable but unforgiving ride
which I won't have much good telemetry and warning about
going south when it does.
[/quote:36c429a250]
Yes, one of the many myths about "man-rating" is that it means that
the vehicle has somehow been made much more reliable (something that's
really not possible on expendables with low flight rate). And it's a
myth to which people who should know better (e.g., many professionals
in the industry) still subscribe.
I have a dream of a day when the phrase "man-rating" will have drifted
entirely out of the lexicon. |
|
|
| Back to top |
|
|
|
| Sander Vesik |
| Posted: Sun Feb 20, 2005 7:00 am |
|
|
|
Guest
|
Fred J. McCall <fmccall@earthlink.net> wrote:
[quote:00b3b21a87]"Ed Kyle" <edkyle99@hotmail.com> wrote:
:Henry Spencer wrote:
:> In article <6p6b019hhp1qtip0qo9vo7c3svn2vmcldn@4ax.com>,
:> Fred J. McCall <fmccall@earthlink.net> wrote:
:> >:Not necessarily. SRBs don't have to be terminatable
:> >:for there to be viable warning and escape systems for
:> >:the crew riding on top.
:
:> >Name a single man-rated solid fuel vehicle anywhere during the
:history
:> >of space, other than the STS with SRBs.
:
:> The original Titan IIIC, which was built to carry Dyna-Soar.
:
:Ariane 5, designed to launch the Hermes spaceplane.
Let's wait until they stop blowing up, shall we?
[/quote:00b3b21a87]
There is extremely unlikely to be another blowup until such
day as and when they roll out Ariane ECB.
[quote:00b3b21a87]
Hermes spaceplane? Another paper vehicle.
[/quote:00b3b21a87]
So? Ariane was designed so that it could be use as and when
Hermes becomes available.
--
Sander
+++ Out of cheese error +++ |
|
|
| Back to top |
|
|
|
| Ed Kyle |
| Posted: Sun Feb 20, 2005 11:10 am |
|
|
|
Guest
|
Henry Spencer wrote:
[quote:97327edf8a]... The
problem Ariane 5 has with being competitive in the comsat market is
not
optimization for Hermes, but the rapid growth in high-end-comsat size
during Ariane 5's prolonged gestation. ...
... The main reason for building a new launcher was that
the comsats increasingly no longer fit in half an Ariane 4, and A4
wasn't
competitive with only a single payload. Alas, the guys writing the
spec
underestimated the rate of growth and the time it would take to get a
replacement launcher going, and undersized Ariane 5, which now has
the
same problem.
[/quote:97327edf8a]
Isn't this a chicken and egg problem? Aren't comsats
simply built as large and heavy as the available
launch capacity? During the mid-1990s, Arianespace
provided Ariane 44L, which could loft two 2+ ton sats
or one 4.9 ton sat, so comsat builders and buyers
pushed the mass up to 4.9 tons. Proton, a match to
Ariane 44L mass capability, and China's 5 ton Long
March 3B entered the commercial market at about the
same time.
If Ariane 5G had arrived sooner, it might have had a
chance to drive the defacto comsat size up to 6.6
tons, minimizing the Proton/Zenit market. But the
market seems to move faster than the launch vehicle
development. Consider that the Atlas 5-431 now
prepping for launch will boost a nearly 6 ton
(Inmarsat) payload.
Perhaps rockets should only be replaced by designs
that doubletheir payload capability.
- Ed Kyle |
|
|
| Back to top |
|
|
|
| Fred J. McCall |
| Posted: Sun Feb 20, 2005 5:42 pm |
|
|
|
Guest
|
Sander Vesik <sander@haldjas.folklore.ee> wrote:
:Fred J. McCall <fmccall@earthlink.net> wrote:
:> "Ed Kyle" <edkyle99@hotmail.com> wrote:
:>
:> :Henry Spencer wrote:
:> :> In article <6p6b019hhp1qtip0qo9vo7c3svn2vmcldn@4ax.com>,
:> :> Fred J. McCall <fmccall@earthlink.net> wrote:
:> :> >:Not necessarily. SRBs don't have to be terminatable
:> :> >:for there to be viable warning and escape systems for
:> :> >:the crew riding on top.
:> :> >
:> :> >Name a single man-rated solid fuel vehicle anywhere during the
:> :history
:> :> >of space, other than the STS with SRBs.
:> :>
:> :> The original Titan IIIC, which was built to carry Dyna-Soar.
:> :
:> :Ariane 5, designed to launch the Hermes spaceplane.
:>
:> Let's wait until they stop blowing up, shall we?
:
:There is extremely unlikely to be another blowup until such
:day as and when they roll out Ariane ECB.
Does that mean they won't be launching any more?
:> Hermes spaceplane? Another paper vehicle.
:
:So? Ariane was designed so that it could be use as and when
:Hermes becomes available.
Which looks pretty much like it will be around the First of Never.
http://www.astronautix.com/craft/hermes.htm
--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw |
|
|
| Back to top |
|
|
|
| Henry Spencer |
| Posted: Sun Feb 20, 2005 6:28 pm |
|
|
|
Guest
|
In article <1108915851.055508.133200@l41g2000cwc.googlegroups.com>,
Ed Kyle <edkyle99@hotmail.com> wrote:
[quote:51fe548d53]Isn't this a chicken and egg problem? Aren't comsats
simply built as large and heavy as the available
launch capacity?
[/quote:51fe548d53]
The heaviest ones, yes. But the owners of the big birds expect them to be
expensive to launch. Arianespace's bread and butter have historically
come from launching mid-range comsats two at a time.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert | henry@spsystems.net |
|
|
| Back to top |
|
|
|
| John Schilling |
| Posted: Mon Feb 21, 2005 2:53 pm |
|
|
|
Guest
|
henry@spsystems.net (Henry Spencer) writes:
[quote:4ddcb3dfee]In article <1108915851.055508.133200@l41g2000cwc.googlegroups.com>,
Ed Kyle <edkyle99@hotmail.com> wrote:
Isn't this a chicken and egg problem? Aren't comsats
simply built as large and heavy as the available
launch capacity?
The heaviest ones, yes. But the owners of the big birds expect them to be
expensive to launch. Arianespace's bread and butter have historically
come from launching mid-range comsats two at a time.
[/quote:4ddcb3dfee]
Which is more difficult to arrange on a purely commercial basis than
Arianespace had expected. An error compounded by jumping the gun on
building the launcher for the biggest comsats, when most of customers
were satisified with midsized birds that can go up on any launcher.
Ariane V is not the right launcher for this decade, and it's going to
take some less than subtle political pressure on the market to keep
it alive. Ariane IV, single-manifesting the big birds and doubling
up the commodity mid-sized satellites, would be a nice thing for
Arianespace to have it its catalog right about now. Oops.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schillin@spock.usc.edu * for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition * |
|
|
| Back to top |
|
|
|
| Ed Kyle |
| Posted: Mon Feb 21, 2005 4:32 pm |
|
|
|
Guest
|
John Schilling wrote:
[quote:1f8c8bf56c]
Ariane V is not the right launcher for this decade, and it's going to
take some less than subtle political pressure on the market to keep
it alive. Ariane IV, single-manifesting the big birds and doubling
up the commodity mid-sized satellites, would be a nice thing for
Arianespace to have it its catalog right about now. Oops.
[/quote:1f8c8bf56c]
I agree that Arianespace may have retired
Ariane 4 too soon, but Ariane 5 might turn
out to be more successful than common wisdom
currently allows one to expect. Ariane 5 has
a 35-payload backlog right now - more than any
other single launch vehicle in the world.
- Ed Kyle |
|
|
| Back to top |
|
|
|
| Fred J. McCall |
| Posted: Sun Feb 27, 2005 12:07 am |
|
|
|
Guest
|
"Ed Kyle" <edkyle99@hotmail.com> wrote:
:Fred J. McCall wrote:
:> "Ed Kyle" <edkyle99@hotmail.com> wrote:
:>
:> :Henry Spencer wrote:
:> :> In article <6p6b019hhp1qtip0qo9vo7c3svn2vmcldn@4ax.com>,
:> :> Fred J. McCall <fmccall@earthlink.net> wrote:
:> :> >Name a single man-rated solid fuel vehicle anywhere during the
:> :history
:> :> >of space, other than the STS with SRBs.
:> :>
:> :> The original Titan IIIC, which was built to carry Dyna-Soar.
:> :
:> :Ariane 5, designed to launch the Hermes spaceplane.
:>
:> Let's wait until they stop blowing up, shall we?
:
:Right now, Ariane 5ECA is the world's most powerful,
:successfully-flown rocket in production and flying.
When it works.
:The last Ariane 5 "blow up" happened in December 2002.
:There have been seven consecutive successes since.
Wow, only 1 in 8 explodes? Not a ride I'd want to take.
:By the way, none of the four Ariane 5 mission failures
:that have occurred (out of 21 flights)
Around 25% failures. Even better.
:involved the
:vehicle's solid rocket boosters. Two were outright
:failures of liquid propulsion systems. Two were
:flight control issues. All four failures would have
:been survivable if a crew carrying system with an
:escape system had been the payload.
For some definition of 'escape system'.
:> Hermes spaceplane? Another paper vehicle.
:
:It was well into development - and Ariane 5 *was*
:developed to carry it. That is why Ariane 5 has
:had to be so extensively upgraded to compete in the
:comsat market. It was not optimized for that work
:from the outset.
I could swear someone else already exploded (so to speak) that one.
--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw |
|
|
| Back to top |
|
|
|
| Ed Kyle |
| Posted: Sun Feb 27, 2005 1:59 am |
|
|
|
Guest
|
Fred J. McCall wrote:
[quote:fa94187ea9]"Ed Kyle" <edkyle99@hotmail.com> wrote:
:Right now, Ariane 5ECA is the world's most powerful,
:successfully-flown rocket in production and flying.
When it works.
[/quote:fa94187ea9]
The revised Ariane 5ECA design (with the
corrected Vulcain 2 engine) worked perfectly on
its inaugural flight. The Ariane 5G series has
a better record than Delta IV and H-IIA, and it
is on a par with Zenit 3. In the large
commercial payload class, only Proton stands
head and shoulders above Ariane 5 in terms of
demonstrated reliablility at the present time.
Commercial launch customers are confident
enough in Ariane 5 to have given it the world's
largest launch backlog at 35 satellites.
[quote:fa94187ea9]:
:It was well into development - and Ariane 5 *was*
:developed to carry it. That is why Ariane 5 has
:had to be so extensively upgraded to compete in the
:comsat market. It was not optimized for that work
:from the outset.
I could swear someone else already exploded (so to speak) that one.
[/quote:fa94187ea9]
The Ariane 5 design was originated to launch Hermes
and was driven by Hermes mass requirements. Original
plans called for an upgrade based on Ariane 4, but
Hermes grew heavier, forcing a new design. Ariane 5
ended up being as big as it was because Hermes
required it to be that big. ESA approved and funded
the development of Hermes and Ariane 5 at the same
time. Development proceeded simultaneously for several
years until Hermes mass and costs grew too high and the
project was shelved. By then the Ariane 5 design was
set - having expanded still further to handle Hermes.
That Ariane 5 would also launch commercial satellites
was always a given, but those requirements did not
drive the design.
- Ed Kyle |
|
|
| Back to top |
|
|
|
| Will McLean |
| Posted: Sun Feb 27, 2005 1:45 pm |
|
|
|
Guest
|
Fred J. McCall wrote:
[quote:637405cc09]"Ed Kyle" <edkyle99@hotmail.com> wrote:
:Fred J. McCall wrote:
:> "Ed Kyle" <edkyle99@hotmail.com> wrote:
:
:> :Henry Spencer wrote:
:> :> In article <6p6b019hhp1qtip0qo9vo7c3svn2vmcldn@4ax.com>,
:> :> Fred J. McCall <fmccall@earthlink.net> wrote:
:> :> >Name a single man-rated solid fuel vehicle anywhere during the
:> :history
:> :> >of space, other than the STS with SRBs.
:> :
:> :> The original Titan IIIC, which was built to carry Dyna-Soar.
:> :
:> :Ariane 5, designed to launch the Hermes spaceplane.
:
:> Let's wait until they stop blowing up, shall we?
:
:Right now, Ariane 5ECA is the world's most powerful,
:successfully-flown rocket in production and flying.
When it works.
:The last Ariane 5 "blow up" happened in December 2002.
:There have been seven consecutive successes since.
Wow, only 1 in 8 explodes? Not a ride I'd want to take.
[/quote:637405cc09]
It's not such a bad record for a launcher that early in its history.
R-7, Atlas and Titan II all had worse records for their first twenty
flights.
Note that Mercury, Gemini and Soyuz all used solids for part of every
flight.
Will McLean |
|
|
| Back to top |
|
|
|
| Fred J. McCall |
| Posted: Mon Feb 28, 2005 12:42 am |
|
|
|
Guest
|
"Will McLean" <mclean1382@aol.com> wrote:
:Note that Mercury, Gemini and Soyuz all used solids for part of every
:flight.
The only solids I'm aware of that were used for the first two are the
separation and retro motors. These hardly fall in the category of
solid booster motors.
--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn |
|
|
| Back to top |
|
|
|
|
|
All times are GMT - 5 Hours
The time now is Fri Dec 11, 2009 12:43 pm
|
|