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#540 by Zed_Noir on 24 Aug, 2016 08:04
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Rocket lab will need Alaska pad for DOD missions as I doubt DOD would be allow their payloads launched from NZ.
Maybe easier & cheaper to staged Electron polar launches from Launch Complex 576 at VAFB. -
#541 by russianhalo117 on 24 Aug, 2016 19:42
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US PSCA launches will be retrograde orbits and SSO CCAFS launches will be fore US LEO and WFF is considered for high energy orbits. Discussions are ongoing with Space Florida and MARSRocket lab will need Alaska pad for DOD missions as I doubt DOD would be allow their payloads launched from NZ.
Maybe easier & cheaper to staged Electron polar launches from Launch Complex 576 at VAFB. -
#542 by Prober on 25 Aug, 2016 13:28
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New Update article, video etc.
http://forum.nasaspaceflight.com/index.php?topic=33141.msg1560147#msg1560147 -
#543 by orulz on 25 Aug, 2016 19:58
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Even if they don't make December for their first launch, presumably there are other somewhat exciting milestones that they need to go through before launch that they will be able to do once they have the pad set up - such as static test fires of the fully integrated first stage? Rocket Lab is one of the more exciting things going on in spaceflight right now.
Even if their first rocket fails, if they make it past stage separation and the second stage ignites successfully, I think their future will be safe, for now. Especially if they make it to orbit, even the wrong orbit, and even if something goes wrong while deploying the payload, I think their customers will actually have increased confidence - it's proof that the concepts involved are all valid and that they're close to making it work- just need to polish the design.
There are too many things that can go wrong for the first few launches to all go smoothly - even something that might seem trivial like fairing separation can cause snags.
What I hope we do not see, especially on the first flight, is a failure of the first stage whether by RUD or loss of guidance or whatever. I do however hope they are capitalized to recover from such a possibility. -
#544 by yg1968 on 31 Aug, 2016 03:06
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#545 by high road on 31 Aug, 2016 11:43
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Do they have downlink and/or tracking this time?
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#546 by Sam Ho on 03 Sep, 2016 12:15
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Article saying they were not affected by the earthquake and everything is still on track.
http://spacenews.com/rocket-lab-launch-site-not-damaged-in-new-zealand-earthquake/ -
#547 by NZ1 on 04 Sep, 2016 00:32
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This quote is interesting. It possibly suggests that batteries will be ejected on the way up, to progressively save weight.
"Lithium batteries will be jettisoned, possibly into NZ water"
They are looking at resuseability.
"We are continuing to consider ways of recovering and reusing the vehicle to further reduce any potential environmental impacts."
http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11702310 -
#548 by CameronD on 05 Sep, 2016 00:08
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This quote is interesting. It possibly suggests that batteries will be ejected on the way up, to progressively save weight.
"Lithium batteries will be jettisoned, possibly into NZ water"
They are looking at resuseability.
"We are continuing to consider ways of recovering and reusing the vehicle to further reduce any potential environmental impacts."
http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11702310
"tis interesting indeed and sounds like the NZ Gov'ment could get themselves into much hot water if they "permitted" uncontrolled dumping. Memories of the 'Rena' disaster are still fresh...
My take on their re-usability effort is a simple parachute recovery into the ocean for collection on a nice day by a borrowed fishing trawler... nothing terribly extraordinary and even then only after they get a few successes under their belts.
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#549 by Davidthefat on 05 Sep, 2016 20:06
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This quote is interesting. It possibly suggests that batteries will be ejected on the way up, to progressively save weight.
"Lithium batteries will be jettisoned, possibly into NZ water"
They are looking at resuseability.
"We are continuing to consider ways of recovering and reusing the vehicle to further reduce any potential environmental impacts."
http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11702310
I see it as the lithium battery raised concerns specifically and they were simply addressing it in their statement. I see no reason why the batteries will be jettisoned independently from the stage. The whole stage will be discarded, and lithium batteries are among the materials being jettisoned. -
#550 by Steven Pietrobon on 06 Sep, 2016 06:23
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I see no reason why the batteries will be jettisoned independently from the stage. The whole stage will be discarded, and lithium batteries are among the materials being jettisoned.
As the batteries are used up, they are discarded during flight. For example, the battery pack could be split into four separate batteries during a two minute flight. After 30 seconds the first battery is empty and released, at one minute the second battery is empty and released and at 90 seconds the third battery is released. This means that less unnecessary mass is carried further into flight, increasing vehicle performance. -
#551 by QuantumG on 06 Sep, 2016 07:23
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I see no reason why the batteries will be jettisoned independently from the stage. The whole stage will be discarded, and lithium batteries are among the materials being jettisoned.
As the batteries are used up, they are discarded during flight. For example, the battery pack could be split into four separate batteries during a two minute flight. After 30 seconds the first battery is empty and released, at one minute the second battery is empty and released and at 90 seconds the third battery is released. This means that less unnecessary mass is carried further into flight, increasing vehicle performance.
Is that what they said they're doing, or just an explanation for why it might be useful?
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#552 by TrevorMonty on 06 Sep, 2016 14:56
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This staged jettisoning system would be even more effective for 2nd stage when it will burn for longer.I see no reason why the batteries will be jettisoned independently from the stage. The whole stage will be discarded, and lithium batteries are among the materials being jettisoned.
As the batteries are used up, they are discarded during flight. For example, the battery pack could be split into four separate batteries during a two minute flight. After 30 seconds the first battery is empty and released, at one minute the second battery is empty and released and at 90 seconds the third battery is released. This means that less unnecessary mass is carried further into flight, increasing vehicle performance. -
#553 by savuporo on 06 Sep, 2016 15:08
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As the batteries are used up, they are discarded during flight. For example, the battery pack could be split into four separate batteries during a two minute flight. ..
Except for in applications like this, you likely actually do need the full battery to deliver the required power to run the pump. Specific power matters just as well as specific energy. You cant drop half the pack and still pull the full amps.
I'm pretty sure the mention in the article talks about batteries ending up in the ocean together with the expended stage, not being jettisoned, as it talks about kerosene and batteries in the same sentence. -
#554 by Steven Pietrobon on 07 Sep, 2016 12:17
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Is that what they said they're doing, or just an explanation for why it might be useful?
Explanation of why it would be useful.Except for in applications like this, you likely actually do need the full battery to deliver the required power to run the pump. Specific power matters just as well as specific energy. You cant drop half the pack and still pull the full amps.
Yes you're right. Let the total energy be E = P*T where P is power in Watts and T is time in seconds.
For a battery pack the power P = V*I where V is the total voltage and I is the total current in Amps.
Each battery has energy Eb = 3600*Vb*Ab where Vb is the battery voltage and Ab is the battery Amp hour rating (1 hour is 3600 seconds).
The maximum battery current Ib = C*Ab where C is the current rating multiplier.
We have E = T*V*I = T*Ns*Vb*Np*C*Ab where Ns is the number of batteries in series in each string and Np the number of parallel strings of batteries. Total number of batteries is
E/Eb = T*Ns*Vb*Np*C*Ab/(3600*Vb*Ab) = Ns*Np*T*C/3600
However, as we know the total number of batteries is Ns*Np, this means the optimal battery configuration requires T*C = 3600 (this is the equation to remember!).
For a first stage flight of 180 seconds (3 minutes), that would require a C rating of 20. Batteries of this C rating are available. See
http://www.all-battery.com/highcrateli-polymer.aspx
If we have two batteries operating at 90 seconds each, then the required C rating of each battery pack needs to double to 40. I couldn't find any batteries with that high a C rating. Maximum seems to be C = 25.
http://www.all-battery.com/25c2500mah222v6sli-polylipobatterypack.aspx -
#555 by Comga on 07 Sep, 2016 13:34
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"tis interesting indeed and sounds like the NZ Gov'ment could get themselves into much hot water if they "permitted" uncontrolled dumping. Memories of the 'Rena' disaster are still fresh...
I know that you know what the "Rena disaster" is, but a link would help the rest of us.US PSCA launches will be retrograde orbits and SSO CCAFS launches will be fore US LEO and WFF is considered for high energy orbits. Discussions are ongoing with Space Florida and MARS
Wow. Almost a quarter of the "words" in that sentence are acronyms. Impressive even for NSF.
And the stuff about sequentially discarding batteries is neat theory, but is not part of Rocketlabs's plan, is it?
Cheers! -
#556 by acsawdey on 07 Sep, 2016 15:05
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For a first stage flight of 180 seconds (3 minutes), that would require a C rating of 20. Batteries of this C rating are available. See
http://www.all-battery.com/highcrateli-polymer.aspx
If we have two batteries operating at 90 seconds each, then the required C rating of each battery pack needs to double to 40. I couldn't find any batteries with that high a C rating. Maximum seems to be C = 25.
http://www.all-battery.com/25c2500mah222v6sli-polylipobatterypack.aspx
Yep, this is exactly what I found when trying to make pack sizing calculations, 25C is the highest rated discharge rate you see advertised, and 20C is what you need for the first stage. It seems like the second stage is the place where ejecting batteries might make sense, it's a much longer burn of only a single engine.
http://forum.nasaspaceflight.com/index.php?topic=37308.msg1359831#msg1359831 -
#557 by savuporo on 07 Sep, 2016 21:03
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If we have two batteries operating at 90 seconds each, then the required C rating of each battery pack needs to double to 40. I couldn't find any batteries with that high a C rating. Maximum seems to be C = 25.
You can actually find cell designs that are able to withstand higher C ratings quite well, for short periods as you are dealing with temperature rise and cooling issues too. It does shorten the cycle life, but that would be irrelevant for this app anyway. But packs are normally engineered for both capacity and power rating together, designing a pack that could split like this sounds like unnecessary level of complexity and risk.It seems like the second stage is the place where ejecting batteries might make sense, it's a much longer burn of only a single engine.
Long burn at much lower power being the key. But still, you'd have ejection mechanisms that would add weight, potential GN&C stability issues, further pack engineering constraints for making it modular .. -
#558 by ringsider on 08 Sep, 2016 11:08
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And the stuff about sequentially discarding batteries is neat theory, but is not part of Rocketlabs's plan, is it?
It's interesting to read this here as I heard the same story - that they will jettison batteries en route, and not just as part of the S1 sep - privately about two months ago. I can't confirm it, it's just something I heard at a conference. It does make sense from a delta-V point of view, but it's more complexity.
The whole electric turbopump angle is interesting but only works for engines of this scale. They have locked themselves into a certain technical approach / solution that has engineering advantages but performance tradeoffs in terms of inert mass and long term scalabilty of the solution. The energy density is the main issue. -
#559 by ringsider on 08 Sep, 2016 12:47
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Is that what they said they're doing, or just an explanation for why it might be useful?
Explanation of why it would be useful.Except for in applications like this, you likely actually do need the full battery to deliver the required power to run the pump. Specific power matters just as well as specific energy. You cant drop half the pack and still pull the full amps.
Yes you're right. Let the total energy be E = P*T where P is power in Watts and T is time in seconds.
For a battery pack the power P = V*I where V is the total voltage and I is the total current in Amps.
Each battery has energy Eb = 3600*Vb*Ab where Vb is the battery voltage and Ab is the battery Amp hour rating (1 hour is 3600 seconds).
The maximum battery current Ib = C*Ab where C is the current rating multiplier.
We have E = T*V*I = T*Ns*Vb*Np*C*Ab where Ns is the number of batteries in series in each string and Np the number of parallel strings of batteries. Total number of batteries is
E/Eb = T*Ns*Vb*Np*C*Ab/(3600*Vb*Ab) = Ns*Np*T*C/3600
However, as we know the total number of batteries is Ns*Np, this means the optimal battery configuration requires T*C = 3600 (this is the equation to remember!).
For a first stage flight of 180 seconds (3 minutes), that would require a C rating of 20. Batteries of this C rating are available. See
http://www.all-battery.com/highcrateli-polymer.aspx
If we have two batteries operating at 90 seconds each, then the required C rating of each battery pack needs to double to 40. I couldn't find any batteries with that high a C rating. Maximum seems to be C = 25.
http://www.all-battery.com/25c2500mah222v6sli-polylipobatterypack.aspx
I am quoting all because I liked your post.
I think what this means is that they are energy density limited by this solution. Unless battery tech improves to increase the density from the same number (ie., mass) of batteries, they can't energize larger pumps to feed fuel to much larger engines without a quite serious mass penalty. This probably means they need to move to old school turbopumps if the vehicle is to evolve.
