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publiusr

Banned

From: Alabama

Registered: 2005-02-24

Posts: 682

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

I don't know that he is a shuttle hugger, in that there is no orbiter.

I think he sees Ares I as just another EELV rocket we don't need, and I also think that Ares I may be a stumbling block to Ares V--and not so much a help.

I have a bad feeling that Griffin might get Ares I done--with a backlash against manned spaceflight killing the CaLV support.

Direct is a means of getting engines under the ET as quickly as we can, so that we will be farther down the road to getting a true HLLV than if we build a dedicated upper stage for Ares I CLV--and wind up getting bogged down on that. Perhaps he can get Direct under contract before the big Congress switch. Probably not.

I am of two minds on the matter myself--and really want to see that big Ares V.

But the Direct method is better than having three EELV class rockets and no HLLVs. That might be the road we are heading down.

I hope I'm wrong.

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

Shuttle huggers are people that are irrationally attached to Shuttle (or its components) for sentimental reasons. Keeping the old launch facilities and retaining as much Shuttle hardware as possible makes me suspect.

None of the EELV rockets have what it takes to carry a capsule large enough to seat four plus the fuel needed to return from Lunar orbit back to Earth. The biggest Atlas-V comes a few tonnes short and the big tripple-barrel Delta would probably be borderline if it were reinforced to meet human flight structural standards. The Atlas would require some serious modification and upgrades, and it would still have those flimsy plastic solid rocket boosters, not to mention a "man capable" launch pad that it presently lacks. The big tripple Delta, even if it were stiffend up, isn't responsive nor affordable, to say nothing of safety with its cheap engines, huge fuel tanks, and terrible acceleration. Neither of the EELVs in any concievable iteration would be any better at launching CEV than Ares-I would, nor would probably cost much more after everything is developed.

Backlash against manned spaceflight? If there was no backlash after the age and a day of the wreched, pointless, useless Shuttle program there suddenly will be a backlash over Ares?

"Direct" is both a misnomer and frankly a cop-out, it sacrifices real heavy lift, Saturn-V class heavy lift, for dinky waterd-down kinda-sorrta heavy lift because the Direct advocates fear having to actually develop new rockets.

"Direct" doesn't have an upgrade path to anything bigger than it either, since it makes a concious decision to limit the diameter of the vehicle and abandon the heavier solid rocket boosters. Making "Direct" into a rocket the size of Ares-V would be about as hard if not harder than the present VSE development plan.

Yes it beats nothing but dinky medium/light launchers, but I don't think its a very good deal.

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[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

publiusr

Banned

From: Alabama

Registered: 2005-02-24

Posts: 682

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

None of the EELV rockets have what it takes to carry a capsule large enough to seat four plus the fuel needed to return from Lunar orbit back to Earth. "Direct" is both a misnomer and frankly a cop-out, it sacrifices real heavy lift, Saturn-V class heavy lift, for dinky waterd-down kinda-sorrta heavy lift because the Direct advocates fear having to actually develop new rockets. .

I understand. I want Ares V myself. Something along the lines of an HLLV.
Someone should remind the incoming Congress that EELVs are red state rockets, and Ares V (with Michold) is a Blue state rocket.

Something to remember when writing your (new) Congressman.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,428

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

Wow such effort back then to kill design based on budget dollars not to meantion the changing direction due to the question of what makes it man rated ....

JeffreyGox

InActive

From: Россия

Registered: 2017-04-09

Posts: 3

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

Hi all just a question, if you bring a car from the UK do you have to have it converted from right to left hand drive?
Thanks
James

GW Johnson

Member

From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,784

Website

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

I don't think so.  In the US,  the laws vary some from state-to-state,  and there are federal standards,  but I know of no requirement for left drive.  I dunno about Canada at all.  I think it's more a matter of minor driver difficulty with the blind spot on the wrong side.  You can handle it,  if you are aware of it. 

GW

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GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,428

Re: BIG advantages of the 4-segments SRB vs. the 5-segments SRB

Ten years on, Northrop Grumman reflects on changes to Solid Rocket Motors from Shuttle to SLS era

Its been that long since the buy out already...

“Usually, thrust predictions [from the models] and that kind of thing are pretty spot on with the big motors.  It’s a pretty well-characterized system, even with the subtle differences moving from the four-segment to the five-segment [design].  Propellant’s about the same.  New insulation.  You have to resize the nozzle because of the new thrust characteristics,” noted Matt.

The added fifth segment will produce 20% greater average thrust and 24% greater total impulse over the Shuttle-era design and will marginally increase the overall burn time of the five-segment SRBs to approximately 2 minutes 12 seconds, ten seconds longer than Shuttle.

The new segment will increase the overall thrust each booster is capable of producing, with each five-segment SRB generating a maximum of 3.6 million lbf (16,103 kN) of thrust for a total thrust from just the SRBs of 7.2 million lbf (32,027 kN) of thrust.

we were close in the figures

Like the Shuttle SRBs, the five-segment SLS boosters will have their propellant grain shaped in such a way to tailor thrust at different parts of flight, allowing the solids to “throttle down” for Max-Q and “throttle back up” thereafter.

Thats different with selective geometry and grain fuels...