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#80
by
Martin FL
on 04 Aug, 2011 19:03
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Brilliant! Just sat coke all over the desk at that
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#81
by
edkyle99
on 04 Aug, 2011 19:21
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Frankly, Ed, I would be more willing to trust my safety to the Aerojet SRB (or even the ATK GEMs) with dozens of missions between them, than the RSRM-V-inline which has none and has serious flight dynamic issues that may make an abort during burn impossible.
The Atlas V solids don't have a lot of flight experience. Tomorrow's planned Atlas 551 launch will represent 16-ish percent of all Atlas V solids flown. Atlas V has 26 flights under its belt. Only 12 of those used strap-on solid motors.
Delta II had two failures, both involving strap-on solids. The first didn't happen until more than 40 flights into the program, by which time more than 350 solids had powered Delta II rockets.
- Ed Kyle
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#82
by
ugordan
on 04 Aug, 2011 19:24
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Kind of interesting CST-100 needs both DEC and 1 solid. Weren't there some folks running around here saying the solid solution would only need to last until DEC flies?
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#83
by
kevin-rf
on 04 Aug, 2011 19:26
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Brilliant! Just sat coke all over the desk at that
Dust buster should clean up the powder
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#84
by
simonbp
on 04 Aug, 2011 19:29
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...launching a full-up orbital Atlas with the intent to have range-safety blow it up mid-flight. That's ballsy.
A full live Centaur would not be required there.
But it will be since:
a. TLYF
b. It can't be flown empty
c. it can't be flown with different fluid
d. too much engineering to do the above
And if that's the case (test-what-you-fly), it means the transonic abort test would be with the single SRB too.
The burn time of the SRB is 94 seconds. By that point the vehicle is ~11 km up and quite supersonic. Thus, a transonic abort would have to occur while the SRB is still burning. Once the capsule has cleared the vehicle, Range Safety would presumably trigger the destruction of the CCB, causing the SRB to shoot off in a random direction. Does the SRB have a separate destruct mechanism, or would it just continue off?
The whole thing does seem like more of a publicity stunt than a real test, so that the marketing department can say, "Look! Our capsule can survive a massive fiery explosion!" Of course all the new media will show is the explosion, not the capsule parachuting down...
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#85
by
Lars_J
on 04 Aug, 2011 19:33
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Yep, I wonder how excited ULA is that Boeing wants to blow up one of their Atlas V's in mid-flight.
Sure, it will provide a LOT of useful data, but it could also be a publicity minefield.
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#86
by
kevin-rf
on 04 Aug, 2011 19:36
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I suspect that if this test is done at close to max-q, even if the RSO doesn't press the button, the aero forces would shred the vehicle. Though to properly do an end to end test, that includes activating the flight termination package.
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#87
by
ugordan
on 04 Aug, 2011 19:38
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Sure, it will provide a LOT of useful data, but it could also be a publicity minefield.
That has occured to me as well. Maybe one of the ways to eliminate this is make this booster visually stand out from the others. Like big letters "THIS WAY UP" on the CCB or some other goofy thing like those crash test dummy yellow-black round markings
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#88
by
kevin-rf
on 04 Aug, 2011 19:42
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Maybe one of the ways to eliminate this is make this booster visually stand out from the others. Like big letters "THIS WAY UP" on the CCB or some other goofy thing like those crash test dummy yellow-black round markings
You mean like for the last 747-8f test flight drawing a 747 across the mid west?
http://flightaware.com/live/flight/BOE523
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#89
by
hydra9
on 04 Aug, 2011 19:57
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George Sowers: CST-100 will use the Atlas 5 412 configuration (one solid strap-on, dual-engine Centaur).
(Jeff Foust)
The strap-on solid bothers me for crewed flight.
- Ed Kyle
They also bother me for the SLS too! But I guess when you have a LAS-- anything goes:-)
But Boeing engineers have already contemplated deriving a simple crew launch booster from the SLS without SRBs.
http://newpapyrusmagazine.blogspot.com/2010/05/boeings-new-hlv-concept-could-be-dc-3.htmlPlus I'm not so sure if Boeing executives really want the CST-100 to be dependent on launch vehicles manufactured by other companies in the long run-- especially if space tourism really takes off.
Marcel F. Williams
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#90
by
Jim
on 04 Aug, 2011 20:02
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Plus I'm not so sure if Boeing executives really want the CST-100 to be dependent on launch vehicles manufactured by other companies in the long run-- especially if space tourism really takes off.
Marcel F. Williams
Another clue less post. You have a habit of spreading them everywhere. What you are sure of doesn't mean squat and shows that you don't know squat either.
ULA is not" other companies". Boeing owes 1/2 of ULA.
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#91
by
Danderman
on 04 Aug, 2011 20:05
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Atlas V 400 constrains the capsule mass + LAS to 20,000 lbs. Atlas V 500 can accommodate more weight, using the payload fairing for support, but I don't see how a capsule could fly inside a payload fairing.
CAnt find the source, but I believe it was previously mentioned that the Atlas V for CST-100 would be the 41X variety rather than 400
Any Atlas V-4XX vehicle has a weight constraint of 20,000 lbs, regardless of how many Centaur engines or strap-ons are used. Its a structural constraint.
To remove the constraint, Atlas V-5XX is used, as the payload fairing can support the additional weight. However, the Boeing capsule will not use a 5xx series Atlas.
How Boeing is going to get around that constraint is a mystery to me.
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#92
by
Jim
on 04 Aug, 2011 20:05
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#93
by
Jim
on 04 Aug, 2011 20:08
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Atlas V 400 constrains the capsule mass + LAS to 20,000 lbs. Atlas V 500 can accommodate more weight, using the payload fairing for support, but I don't see how a capsule could fly inside a payload fairing.
CAnt find the source, but I believe it was previously mentioned that the Atlas V for CST-100 would be the 41X variety rather than 400
Any Atlas V-4XX vehicle has a weight constraint of 20,000 lbs, regardless of how many Centaur engines or strap-ons are used. Its a structural constraint.
To remove the constraint, Atlas V-5XX is used, as the payload fairing can support the additional weight. However, the Boeing capsule will not use a 5xx series Atlas.
How Boeing is going to get around that constraint is a mystery to me.
Why wouldn't the 5XX be used?
Or a thicker Centaur can be used.
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#94
by
Danderman
on 04 Aug, 2011 20:10
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Atlas V 400 constrains the capsule mass + LAS to 20,000 lbs. Atlas V 500 can accommodate more weight, using the payload fairing for support, but I don't see how a capsule could fly inside a payload fairing.
CAnt find the source, but I believe it was previously mentioned that the Atlas V for CST-100 would be the 41X variety rather than 400
Any Atlas V-4XX vehicle has a weight constraint of 20,000 lbs, regardless of how many Centaur engines or strap-ons are used. Its a structural constraint.
To remove the constraint, Atlas V-5XX is used, as the payload fairing can support the additional weight. However, the Boeing capsule will not use a 5xx series Atlas.
How Boeing is going to get around that constraint is a mystery to me.
Why wouldn't the 5XX be used?
Or a thicker Centaur can be used.
The difference between the 4xx and 5xx series is the payload fairing used for the 5xx series - but the Boeing capsule cannot be accommodated inside the payload fairing; ergo, Boeing has already decided on using the 4xx series.
As for a "thicker" Centaur, *rockets aren't Legos*, you can't just "thicken" a Centaur.
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#95
by
Jim
on 04 Aug, 2011 20:12
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As for a "thicker" Centaur, *rockets aren't Legos*, you can't just "thicken" a Centaur.
yes, it can. The skin gage for it and the old Atlas were changed at will to suit mission requirements in the past
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#96
by
Jim
on 04 Aug, 2011 20:14
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The difference between the 4xx and 5xx series is the payload fairing used for the 5xx series - but the Boeing capsule cannot be accommodated inside the payload fairing; ergo, Boeing has already decided on using the 4xx series.
A fairing can encapsulate just the Centaur, which was the idea for OSP.
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#97
by
CitabriaFlyer
on 04 Aug, 2011 20:22
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Jim or any expert,
How does the 421 configuration (2 engine Centaur and 1 solid) help you? Is it more payload to orbit?
Is it a more benign trajectory?
Is it something else?
How concerned would you be riding with a solid attached? Is the performance/safety of the extra thrust worth any risk of a solid rocket?
I guess Boeing believes that to be the case.
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#98
by
Ben the Space Brit
on 04 Aug, 2011 20:27
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I'm no expert but...
How does the 421 configuration (2 engine Centaur and 1 solid) help you? Is it more payload to orbit?
It's 412 - PLF size, number of solids, number of engines on Centaur
The benefit is payload to orbit. The 5m PLF weighs more and the Dual Engine Centaur has higher thrust meaning it sacrifices the ability to push things beyond LEO in exchange for pushing more to LEO. The solid is just for extra thrust in the first ~75 seconds of flight.
There
is an increased risk from using a solid rocket booster on the vehicle, although it is mostly a statistical issue. That said, I imagine ULA would not have recommended the use of an SRM (especially not the asymmetrical 1-booster option) unless it was really necessary.
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#99
by
marsavian
on 04 Aug, 2011 20:33
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They are also using dual-engine Centaur on all man-rated Atlas Vs for LOC/LOM and redundancy reasons I believe. Extra engine in case one doesn't fire at all on staging.
