Titan SRMU Future Use?

Sorry if this has already been addressed.

Watching the next to last Titan the other night
got me to wondering about those powerful Alliant
solid rocket motor (upgrades) SRMU's that poured
out 1,500 metric tons of combined thrust at
liftoff. These babies were developed at great
cost during the mid-1990s and will, after the
last Titan flies in a couple of three months,
have flown only 17 missions. All SRMUs have
flown successfully to date.

Is there any possibility that these high-thrust
rocket motors could be applied to another launch
vehicle? My back-of-the-envelope figuring hints
that a Delta IV or Atlas V hauled aloft by twin
SRMUs could put well more than 30 metric tons
into LEO - significantly more than either EELV
Heavy design.

NASA's going to need heavier lift to go to the
Moon. Could SRMU, a rocket already bought and
paid for and about to be tossed into the
dustbin after having hardly been broken in, play
a role? Or is it too late?

- Ed Kyle

Ed Kyle wrote:

Could SRMU, a rocket already bought and paid for

Any estimate of what the marginal cost of more SRMUs
would be?

"Ed Kyle" wrote in news:1114900650.594337.300570
@g14g2000cwa.googlegroups.com:

Is there any possibility that these high-thrust
rocket motors could be applied to another launch
vehicle? My back-of-the-envelope figuring hints
that a Delta IV or Atlas V hauled aloft by twin
SRMUs could put well more than 30 metric tons
into LEO - significantly more than either EELV
Heavy design.

NASA's going to need heavier lift to go to the
Moon. Could SRMU, a rocket already bought and
paid for and about to be tossed into the
dustbin after having hardly been broken in, play
a role? Or is it too late?

How much do these motors cost per flight, and how
much would it cost to modify the existing EELVs
and launch facilities to work with them? By
reducing the number of EELV booster units required
to be manufactured, would the costs then go up?
The whole concept of EELV revolves around simplification
and reduction of _unique_ parts and systems per
launch vehicle.

That said, the extra lift given to Delta IV would
be attractive since it has less takeoff thrust to
work with.

--Damon

Allen Thomson wrote:
Ed Kyle wrote:

Could SRMU, a rocket already bought and paid for

Any estimate of what the marginal cost of more SRMUs
would be?

SRMU cost information is hard to find. One detail
I located was a cost item in a congressional budget
that listed the hardware cost of performing one
SRMU qualification test to be $62.8 million
(in ~FY 1997 dollars). But with Titan, costs were
all about build-rates. During the early 1990s,
Lockheed Martin was building up to six Titan IV
vehicles per year for $1-1.2 billion. During the
late 1990s, the company was providing two vehicles
per year for $1 billion. The fixed costs of this
program were substantial because everything had been
sized for a production rate of up to 10 per year.
The SRMU contract was let during the early 1990s,
so Hercules (later ATK) built facilities to handle
the higher launch rates - but it never built more
than two SRMU sets per year. Hercules actually
sued Martin (its prime contractor) for $100s of
millions because of this. The settlement payout
ended up being part of the total Titan program
costs, as near as I can tell.

So ATK might have been able to build one SRMU set
for $125.6 million. But it might also have been
able to build two or four or six for the same total
price if the build rate was fast enough.

- Ed Kyle

Damon Hill wrote:
"Ed Kyle" wrote in
news:1114900650.594337.300570
@g14g2000cwa.googlegroups.com:

Is there any possibility that these high-thrust
rocket motors could be applied to another launch
vehicle? My back-of-the-envelope figuring hints
that a Delta IV or Atlas V hauled aloft by twin
SRMUs could put well more than 30 metric tons
into LEO - significantly more than either EELV
Heavy design.

NASA's going to need heavier lift to go to the
Moon. Could SRMU, a rocket already bought and
paid for and about to be tossed into the
dustbin after having hardly been broken in, play
a role? Or is it too late?

How much do these motors cost per flight, and how
much would it cost to modify the existing EELVs
and launch facilities to work with them? By
reducing the number of EELV booster units required
to be manufactured, would the costs then go up?

As best I can determine from the paucity of publically
available data, one SRMU would have the same ballpark
cost, but would probaly cost 10-20% more, than one
EELV core stage. But an SRMU would seem to provide
a correspondingly higher performance. On the other
hand, I have to agree that the cost of reducing the
EELV core stage build-rates would probably drive the
total costs up too much - unless a much higher total
mass rate to orbit was needed.

One way to reduce facilities costs would be to use
the existing SMARF (and probably Pad 40) at Cape
Canaveral. SMARF cost $millions to build - it was
constructed specifically to handle SRMU - but it
only supported about one dozen launch flows!.

The whole concept of EELV revolves around simplification
and reduction of _unique_ parts and systems per
launch vehicle.

That said, the extra lift given to Delta IV would
be attractive since it has less takeoff thrust to
work with.


On the face of it, it seems a waste to shut down the
program - the world's second most powerful rocket
motor, and the world's most technologically advanced
big solid motor - after so few flights. But SRMU had
a troubled start (with one qual motor failure, a big
lawsuit by Hercules against Martin, a big run-up in
costs, etc.) and I've got to wonder if ATK might be
happy to be rid of the thing. The last SRMU set was
probably manufactured more than two years ago, so the
production capacity is already shut down and will
soon be lost permanently, if it isn't already.

- Ed Kyle

Ed Kyle wrote:


So ATK might have been able to build one SRMU set
for $125.6 million.



Or ATK could build up about 4 RSRMs for the same price...

You haven't defined "performance". The Titan SRB has high thrust but low
specific impulse. The total impulse would be about 850 million
Newton-seconds in a vacuum, whereas the Delta IV booster has about 820
million Newton-seconds, and the Atlas V booster about 1 billion
Newton-seconds. So the performance of these stages is about the same.
Using the very large solid would require extensive modifications to the pads
for either Atlas or Delta.

Murray Anderson

"Ed Kyle" wrote in message
ups.com...
Damon Hill wrote:
"Ed Kyle" wrote in
news:1114900650.594337.300570
@g14g2000cwa.googlegroups.com:

Is there any possibility that these high-thrust
rocket motors could be applied to another launch
vehicle? My back-of-the-envelope figuring hints
that a Delta IV or Atlas V hauled aloft by twin
SRMUs could put well more than 30 metric tons
into LEO - significantly more than either EELV
Heavy design.

NASA's going to need heavier lift to go to the
Moon. Could SRMU, a rocket already bought and
paid for and about to be tossed into the
dustbin after having hardly been broken in, play
a role? Or is it too late?

How much do these motors cost per flight, and how
much would it cost to modify the existing EELVs
and launch facilities to work with them? By
reducing the number of EELV booster units required
to be manufactured, would the costs then go up?

As best I can determine from the paucity of publically
available data, one SRMU would have the same ballpark
cost, but would probaly cost 10-20% more, than one
EELV core stage. But an SRMU would seem to provide
a correspondingly higher performance. On the other
hand, I have to agree that the cost of reducing the
EELV core stage build-rates would probably drive the
total costs up too much - unless a much higher total
mass rate to orbit was needed.

One way to reduce facilities costs would be to use
the existing SMARF (and probably Pad 40) at Cape
Canaveral. SMARF cost $millions to build - it was
constructed specifically to handle SRMU - but it
only supported about one dozen launch flows!.

The whole concept of EELV revolves around simplification
and reduction of _unique_ parts and systems per
launch vehicle.

That said, the extra lift given to Delta IV would
be attractive since it has less takeoff thrust to
work with.


On the face of it, it seems a waste to shut down the
program - the world's second most powerful rocket
motor, and the world's most technologically advanced
big solid motor - after so few flights. But SRMU had
a troubled start (with one qual motor failure, a big
lawsuit by Hercules against Martin, a big run-up in
costs, etc.) and I've got to wonder if ATK might be
happy to be rid of the thing. The last SRMU set was
probably manufactured more than two years ago, so the
production capacity is already shut down and will
soon be lost permanently, if it isn't already.

- Ed Kyle

Murray Anderson wrote:
You haven't defined "performance". The Titan SRB has high thrust but
low
specific impulse. The total impulse would be about 850 million
Newton-seconds in a vacuum, whereas the Delta IV booster has about
820
million Newton-seconds, and the Atlas V booster about 1 billion
Newton-seconds. So the performance of these stages is about the same.

You're right. I should have said "thrust" or
"total impulse". But either way I seem to have
misspoken. Titan SRMU is the third, not the
second, most powerful rocket motor, in terms
of both thrust and total impulse.

But it turns out that it isn't Atlas V CCB that
is number two ahead of SRMU - it is Zenit RD-171
(just barely). I think you may have had a low
number for Titan IVB SRMU total impulse. Perhaps
you used data for the original Titan IVA solid
rocket motor. According to spaceandtech.com,
SRMU had a total impulse of 1,040 kN-sec.

Here is a list of the most powerful active rocket
motors, or single engine/stage combinations, as I
understand it. We'll be crossing SRMU off the
list in a couple of months, and Atlas V CBC seems
designed, in retrospect, to take its place.

Motor/Stage(Engine) Total Impulse
---------------------------------------------
STS RSRM 1,429.5 kN-sec
Zenit 2 (RD-171) 1,063.6 kN-sec
Titan SRMU 1,040.0 kN-sec
Atlas V CCB (RD-180) 996.5 kN-sec
Delta IV CBC (RS-68) 832.7 kN-sec
Ariane 5-E Core (Vulcain-2) 729.0 kN-sec
Ariane 5 EAP 650.0 kN-sec
---------------------------------------------

Note that the Proton first stage would be
No. 2 on this (and on the thrust list) if we
were looking at stage total impulse rather
than motor/engine total impulse.

- Ed Kyle

Using the figures at spaceandtech, plus the figure of 259 seconds sea level
specific impulse from www.astronautix.com, gives a nominal burn time of 106
seconds at full initial thrust. Then using a vacuum thrust of 7500*285.6/259
= 8270 kN, we get total impulse 876,649 kN-sec.
Remember that the thrust generally tapers off in solids, so you can't use
the total burn time times initial thrust.

Murray Anderson

"Ed Kyle" wrote in message
ups.com...
Murray Anderson wrote:
You haven't defined "performance". The Titan SRB has high thrust but
low
specific impulse. The total impulse would be about 850 million
Newton-seconds in a vacuum, whereas the Delta IV booster has about
820
million Newton-seconds, and the Atlas V booster about 1 billion
Newton-seconds. So the performance of these stages is about the same.

You're right. I should have said "thrust" or
"total impulse". But either way I seem to have
misspoken. Titan SRMU is the third, not the
second, most powerful rocket motor, in terms
of both thrust and total impulse.

But it turns out that it isn't Atlas V CCB that
is number two ahead of SRMU - it is Zenit RD-171
(just barely). I think you may have had a low
number for Titan IVB SRMU total impulse. Perhaps
you used data for the original Titan IVA solid
rocket motor. According to spaceandtech.com,
SRMU had a total impulse of 1,040 kN-sec.

Here is a list of the most powerful active rocket
motors, or single engine/stage combinations, as I
understand it. We'll be crossing SRMU off the
list in a couple of months, and Atlas V CBC seems
designed, in retrospect, to take its place.

Motor/Stage(Engine) Total Impulse
---------------------------------------------
STS RSRM 1,429.5 kN-sec
Zenit 2 (RD-171) 1,063.6 kN-sec
Titan SRMU 1,040.0 kN-sec
Atlas V CCB (RD-180) 996.5 kN-sec
Delta IV CBC (RS-68) 832.7 kN-sec
Ariane 5-E Core (Vulcain-2) 729.0 kN-sec
Ariane 5 EAP 650.0 kN-sec
---------------------------------------------

Note that the Proton first stage would be
No. 2 on this (and on the thrust list) if we
were looking at stage total impulse rather
than motor/engine total impulse.

- Ed Kyle