ARES I - NOT to be re-usable?

[docm]

http://www.spaceref.com/news/viewnews.html?id=1177<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Some of the people working on the design of NASA's new Ares I launch vehicle want to delete the requirement to recover and reuse the rocket's first stage. The reason: the weight of hardware required to make recovery possible - and practical.<br /> /><br />NASA sources report that a formal, internal process to change some requirements has been initiated during the on-going requirements definition process for the Ares I. If implemented by NASA <b>this requirements change would delete the recovery and reusability of the Ares I first stage altogether.</b><br /><br />In making this recommendation, <b>this requirements change request cites the fact that somewhere between 20,000 and 25,000 pounds of weight could be saved</b> in the design of the first stage by removing the systems needed to allow it to be recovered after it has been used.<br /><br />Cutting this weight would offer a substantial increase in the payload that the Ares I is capable of lofting - as well as what the Ares V is capable of delivering to orbit as well.<br /><br />Wind tunnel analysis has shown that the flight path that the first stage of the Ares I would fly is higher and more energetic than the one flown by the current 4 segment Space Shuttle SRBs. Some modifications (i.e. additional weight) have already had to be made in existing SRB systems to accommodate this somewhat more extreme flight profile.<p><hr /></p></p></blockquote><br />Soooo.....let me get this right;<br /><br />1. word leaks out that ARES I is underpowered<br /><br />2. NASA goes into a tizzy denying it<br /><br />3. the designers then want to ditch re-usability to save weight<br /><br /><img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[dreada5]

Not certain, but a while ago (before all this talk about the stick being underpowered) I remember hearing that that Ares 1 wouldn't be recovered (don't know which stage) because there weren't any significant savings to be made once retrieval, reprocessing costs had been factored in.

 

[mrmorris]

<font color="yellow">"...I remember hearing that that Ares 1 wouldn't be recovered (don't know which stage) because there weren't any significant savings to be made..."</font><br /><br />Correct. IIRC (I think I do), According to SG, the current boosters cost close to 90% of their purchase cost to refurbish. The 5-segment booster will be flying higher and faster and will be considerably further downrange when it hits ocean, making it considerably harder and more expensive to recover.<br /><br />So making it recoverable means:<br /><br />-- You spend time and dollars developing and testing recovery hardware & methods.<br />-- You lose considerable payload capacity on every launch.<br />-- You won't save much money on each launch making them recoverable.<br /><br />Making them recoverable is more a PR issue than an economic one. So: Good PR -- Neutral (at best) economics -- Bad engineering. My vote says dump the recoverable option now.

 

[barrykirk]

So, if you want really cost effective re-usability, you<br />need to go with liquid fuels.

 

[vonster]

<blockquote><font class="small">In reply to:</font><hr /><p>Cutting this weight would offer a substantial increase in the payload <p><hr /></p></p></blockquote><br /><br />I think you're misreading it, theyre looking to increase payload, not make up for an underpowered system.<br /><br />I wouldnt assume everyone at NASA is stupid and / or lying about this issue? <br /><br />.

 

[rocketwatcher2001]

I'm still waiting for the fly-back boosters. That should make things cheaper in the long run. <div class="Discussion_UserSignature"> </div>

 

[josh_simonson]

Divers have to go down 120' to put a plug in the SRB nozzle for recovery, adding another segment will push that down to about 150'. 120' is the safe limit for diving on air due to nitrogen narcosis, so the recovery divers would need to be retrained for deep dives with mixed air, and require new gear, more pay and more expensive insurance for the more hazardous conditions.<br /><br />That certainly wouldn't close that 10% gap all on it's own, but it's an example of the kind of factors that make re-useing the 5 seg less attractive. It isn't hard to envision re-use being nickled and dimed into a losing proposition given the current margin is so low.

 

[propforce]

Let's add a marine propulsion system to the FSB <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[darkenfast]

The possibility of not recovering the SRB's has been mentioned occasionally since the first ESAS press conference. This is nothing new, just a new target for the "bashers".

 

[holmec]

This would be an operational problem. And it doesn't make sense if you recover Ares V SRBs and not Ares I SRB. <br /><br />So if I were the overall manager of Constellation project I would not allow it since it invites inconsistencies in operations and possible accidents/liabilities, and worse of all CONFUSION. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[dreada5]

You would force your team and the agency to do the following?<br /><br />- spend more money on recovering, processing<br />- reduce the performance of the ARES 1<br />- scrap the current design / redesign ARES 1

 

[trailrider]

I'm not sure where the 20k-25k lbs figure comes from, but you'd certainly have to redesign the Decelerator Sub System (SRB-DSS)...i.e., the parachute system. With the higher trajectory and greater mass you'd have to enlarge the drogue chute. Deployment profile for the drogue would have to be revised. You'd have to either add a fourth main chute (~2500 lbs IIRC) if you use the same 136 ft. dia. hemispherical chutes. There would probably be room in the widened inverted frustum. Forward dome and deck fittings would need redesign. It might be possible to use an automated robot to plug the nozzle. Not sure if the aft skirts would have to be beefed up. Depends on the desired velocity at water impact. Of course, all this will take additional development. <br /><br />Lockheed-Martin would be the logical choice to develop the new SRM-DSS, although I doubt any of the other original personnel are around. (The chief systems engineer passed away about 3 years ago. <img src="/images/icons/frown.gif" /> ) Doubt they'd want any of us anyway...<br /><br />The whole idea of using the SRB for the stage 1 is because of the technology developed from the Shuttle program.<br /><br />Hmmm... Let's see... This will be the same ol' SRB used on the Shuttle...except:<br /><br />1) We need 5 segments instead of 4.<br /><br />2) We need roll control during Stage 1 burn.<br /><br />3) We need to change the position of the separation motors to point nozzle forward in order to back the SRM away from Stage 2/Orion.<br /><br />4) We will change from HTBP to PBAN propellant<br /><br />5) Need a larger nozzle for higher thrust. Not sure about an increase in the size of the TVC packages.<br /><br />6) We need to develop a new Decelerator Subsystem, including possibly developing robotic plug emplacer.<br /><br />7) Liberty Star or Freedom Star will have to go further out in the Atlantic to recover the booster. More costs resulting.<br /><br />The only thing about NOT recovering the Stage 1 is whether it will imme

 

[propforce]

<blockquote><font class="small">In reply to:</font><hr /><p>The whole idea of using the SRB for the stage 1 is because of the technology developed from the Shuttle program. <br /><br />Hmmm... Let's see... This will be the same ol' SRB used on the Shuttle...except: <br /><br />1) We need 5 segments instead of 4. <br /><br />2) We need roll control during Stage 1 burn. <br /><br />3) We need to change the position of the separation motors to point nozzle forward in order to back the SRM away from Stage 2/Orion. <br /><br />4) We will change from HTBP to PBAN propellant <br /><br />5) Need a larger nozzle for higher thrust. Not sure about an increase in the size of the TVC packages. <br /><br />6) We need to develop a new Decelerator Subsystem, including possibly developing robotic plug emplacer. <br /><br />7) Liberty Star or Freedom Star will have to go further out in the Atlantic to recover the booster. More costs resulting. <br /><br />The only thing about NOT recovering the Stage 1 is whether it will immediately break up and sink (STS-4's booster did when the main deck fittings prematurely blew at altitude rather than water impact), or create a hazzard to navigation! <br /><br />After all that, all you have to do is jack up the tail numbers... <p><hr /></p></p></blockquote><br /><br />NASA's ARES 1 design just get better and better <img src="/images/icons/smile.gif" /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[no_way]

<blockquote><font class="small">In reply to:</font><hr /><p>NASA's ARES 1 design just get better and better<p><hr /></p></p></blockquote><br /><br />I saw someone referring to them as "ARSES I/V" somewhere earlier .. im not sure whether its a new codename, simple typo or what ..

 

[scottb50]

I think it should be ARRRRR's, matey. <div class="Discussion_UserSignature"> </div>

 

[radarredux]

> <i><font color="yellow">3. the designers then want to ditch re-usability to save weight</font>/i><br /><br />I remember reading about this as a possibility many months ago, maybe more than a year ago. From what I recall, the reasoning then was: (1) the cost of designing and manufacturing a reusable vehicle was higher than a disposable one and (2) the cost of recovery and refurbishment was still fairly high. Thus, the overall cost advantage of reusability was hard to measure.<br /><br />Now, weight seems to be another another issue in favor of going towards a disposable booster. (It seems weight is almost always an issue)</i>

 

[j05h]

>> "ARSES I/V"<br /> /> "Ares I/V" <br /><br />I think you dropped a letter, Newartist.<br /><br />This is yet another indication: here comes EELV to the rescue. Payload neutrality, high flight rate, fuel depots and more customers for existing rockets creates a market for spaceflight. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[mrmorris]

<font color="yellow">"It seems weight is almost always an issue"</font><br /><br />There is no 'almost' to it... ever. The math of mass fractions makes it a given that spacecraft/booster mass will always be in the top five most important development issues.

 

[tomnackid]

Not recovering the SRBs has been an option since the first shuttle flew. This is nothing new. Engineers study every contingency to see how they could impact performance. Remember the "Walmart LM" a few months back? Some engineering team was tasked with coming up with a design for a lunar module given a worst case scenario regarding funding and mass fraction. Suddenly all of the NASA bashers were proclaiming that this was now THE plan for Constellation and isn't it horrible how NASA has screwed up so bad. This seems to be an emerging pattern in the blogsphere--find a "worst case scenario" contingency report and proclaim it to be the current status of Project Constellation then start with the "I told you so's" and the righteous indignation. There are plenty of legitimate reasons to criticize NASA without twisting the facts.

 

[mrmorris]

I was thinking (always dangerous) about exactly what the 5-segment SRM buys. Obviously it buys some additional dv... but just how much? One more segment can provide no more than 20% additional dv. Less actually, because the additional mass has a vampiric effect on the existing thrust. How far off *is* the performance of the current 4-segment booster and can it be improved to the point where the fifth segment becomes pointless. <br /><br />From Astronautix, I got the following data for the 4-segment SRB:<br /><br />Gross Mass: 589,670 kg<br />Empty Mass: 86,183 kg<br />Thrust(vac): 11,519.8 kN <br />Burn time: 124 sec<br />Total Thrust: 1,428,455 kN s<br /><br />Just for estimation, I'll assume the 5-segment SRB will mass 20% more and burn 20% longer:<br /><br />Gross Mass: 707,604 kg<br />Thrust(vac): 11,519.8 kN <br />Burn time: 149 sec<br />Total Thrust: 1,716,450 kN s<br /><br />The Orion capsule will be capped at 25,000 kg IIRC, but I don't know what the upper-stage will mass. I *think* the general rule of thumb is to assume 20% of the mass of the previous stage. Using the 5-segment booster, this would be 141,521 kg. With these assumptions, the dv imparted to the total system from the two boosters then would be:<br /><br />Total Mass SRB4 stack: 756,191 kg<br />dv SRB4 - 1,889 m/s<br /><br />Total Mass SRB5 stack: 874,125 kg<br />dv SRB5 - 1,963 m/s<br /><br />So -- working the problem in reverse. If we wanted the SRB4 to be able to provide a dv of 1963 m/s, the total system mass would have to be ~727,690 kg. Is it possible to shave 28,501 kg from the SRB4?<br /><br />From this document: SPACE SHUTTLE SOLID ROCKET BOOSTER LIGHTWEIGHT RECOVERY SYSTEM I got the following figures:<br /><br />Payload savings on the SRB are 1:10 (i.e. every 10 kg saved adds another kg of payload)<br />Parachute recovery system: 3855 kg.<br /><br />OK -- so eliminating the idea of recovering the S

 

[radarredux]

> <i><font color="yellow">There is no 'almost' to it... ever. The math of mass fractions makes it a given that spacecraft/booster mass will always be in the top five most important development issues.</font>/i><br /><br />If the organization would, from the get-go, commit to a much larger booster (preferably that already exists) than they think they will need, then they could absorb a little unexpected weight gain.<br /><br />My guess is that it would be tough to get such a proposal funded from the beginning because the initial costs would be too high on paper. It might also be difficult to keep engineers from succumbing to feature creep: "Cool, we have this exta performance, lets add gizmo X or capability Y to the spacecraft." Before they know it, they have maxed out their weight allowance. How many of us have bought a new computer with a huge disk space and said to ourselves, "I'll never fill up that disk." <img src="/images/icons/smile.gif" /></i>

 

[halman]

mrmorris,<br /><br />Very impressive reasoning and calculating, sir! Now, all you have to do is answer the question of why composites are not going to be used for the Ares casings. Would retooling cost more than ATK (isn't that what Morton Thiokol is known as now?) is worth? Does using composite materials require re-engineering the whole rocket? Would the composite rocket put too many people who work on the current rocket out of work? Although mathematics can give us the correct answers to many of our problems, they are of no use when when we deal with politics and the whims of Congress. <div class="Discussion_UserSignature"> The secret to peace of mind is a short attention span. </div>

 

[mrmorris]

<font color="yellow">"Now, all you have to do is answer the question of why composites are not going to be used for the Ares casings."</font><br /><br />Did some more Googling *after* making my post. Found a thread at <i>forum.nasaspaceflight.com</i> that actually discusses the concept of the filament-wound SRBs and removing the recoverability -- although they're looking at it from the viewpoint of the recent allegations that even the 5-segment doesn't cut the mustard and needs a boost.<br /><br />This document is written as if the filament-wound SRBs were fully developed: <i>"NASA was preparing to fly the Space Shuttle from Vandenberg Air Force Base (VAFB) for polar orbit missions. Filament wound case (FWC) SRBs were developed for the higher energy requirements of these missions."</i> Supposedly it was dropped after the Air Force dropped the Shuttle. As to why -- I've seen several ideas, from allegations that the FW is more expensive to the STS simply not needing it with the AF gone, to safety concerns. HeckifIknow which is true.

 

[vogon13]

Sorry for the shaky recollection here, but IIRC, a filament wound SRB was test fired in Utah.<br /><br />It might not have been an unqualified success . . . <br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[nyarlathotep]

<font color="yellow">Just for estimation, I'll assume the 5-segment SRB will mass 20% more and burn 20% longer:</font><br /><br />Adding segments doesn't make the SRB burn longer, it just adds more thrust. If you want to burn longer you need to widen the casing.<br /><br />If NASA is now going to make the motor casings disposible they should probably look up Aerojet in the rolodex and have a larger diameter motor poured on site.