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#420
by
CameronD
on 05 Jan, 2016 21:37
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http://www.rocketlabusa.com/careers/propulsion-careers/propulsion-test-engineer-2/
For security reasons background checks will be undertaken prior to any employment offers being made to an applicant. These checks will include nationality checks as it is a requirement of this position that you be eligible to access equipment and data regulated by the United States’ International Traffic in Arms Regulations. Under these Regulations, you may be ineligible for this role if you do not hold citizenship of Australia, Japan, New Zealand, Switzerland, the European Union or a country that is part of NATO, or if you hold ineligible dual citizenship or nationality. For more information on these Regulations, click here http://www.pmddtc.state.gov/regulations_laws/itar.html.
Thinking of applying for the job, QG??
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#421
by
QuantumG
on 05 Jan, 2016 22:18
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Thinking of applying for the job, QG??
There's few things that could make me move to NZ...
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#422
by
Alf Fass
on 07 Jan, 2016 00:47
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There's few things that could make me move to NZ...
Wow, that is good news...
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#423
by
CameronD
on 07 Jan, 2016 00:53
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There's few things that could make me move to NZ...
Wow, that is good news...
Good for the Kiwis? Or good for Oz??
Fact is, at least there's an active space-launch program, under a supportive government, in Aotearoa.. and that's something that we aren't likely to see in these parts for decades to come.
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#424
by
RoboGoofers
on 13 Jan, 2016 18:10
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is there anything better, currently, than LIon for the turbopump motor? I'm not sure there's an optimized power source for such a use case: very high capacity, non-reusable, light.
-perhaps a flow battery? dump the used electrolyte overboard?
-i read something about cruise missiles using zinc-silver peroxide batteries, but it was a very old article
-run a fuel cell really hot but cool it with LOX? or cool LIon with LOX?
-supercapacitors?
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#425
by
randomly
on 13 Jan, 2016 19:15
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you need both high energy density AND high power density. You need to dump all the energy in a matter of minutes.
flow batteries won't beat out Li-ion, they have both poor energy density and poor power density.
I don't think fuel cells will either, power density limitations. at least not in an overall pro's and con's tradeoff.
The most viable alternative I can think of is hypergolics into a turbine/generator... but that's going away from their goal of simplicity.
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#426
by
gin455res
on 13 Jan, 2016 19:33
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How about one turbo-generator (or piston-generator), running nine fuel, and nine oxidizer electric pumps?
[Perhaps batteries, for boost-back, re-entry and landing for a falcon-9-esque reusable, electron.]
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#427
by
ArbitraryConstant
on 14 Jan, 2016 20:37
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-perhaps a flow battery? dump the used electrolyte overboard?
-i read something about cruise missiles using zinc-silver peroxide batteries, but it was a very old article
-run a fuel cell really hot but cool it with LOX? or cool LIon with LOX?
-supercapacitors?
Supercapacitors might win on the scale of seconds but not minutes. Fuel cells are too heavy. Cruise missiles are storable munitions, different tradeoffs.
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#428
by
Robotbeat
on 14 Jan, 2016 20:44
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There are some fancy chemistry primary lithium batteries that get like 2-3x lithium ion energy density, but I'm not aware of anything that beats good LiPos for high power density.
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#429
by
TrevorMonty
on 14 Jan, 2016 22:11
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One of the other small LVs was also using electric pumps but I can't remember which one.
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#430
by
Skyrocket
on 14 Jan, 2016 22:21
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One of the other small LVs was also using electric pumps but I can't remember which one.
It is the air-launched SALVO rocket, designed by Ventions for DARPA. Very secretive, not much known.
http://space.skyrocket.de/doc_lau/salvo.htm
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#431
by
c4fusion
on 16 Jan, 2016 01:13
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There are some fancy chemistry primary lithium batteries that get like 2-3x lithium ion energy density, but I'm not aware of anything that beats good LiPos for high power density.
Well maybe not power density, but there is a couple of semi commercial products that have higher energy density. One of them is a nano-silicon anode for a lithium chemistry battery:
, interesting lecture by SLAC.
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#432
by
Robotbeat
on 17 Jan, 2016 01:40
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There are some fancy chemistry primary lithium batteries that get like 2-3x lithium ion energy density, but I'm not aware of anything that beats good LiPos for high power density.
Well maybe not power density, but there is a couple of semi commercial products that have higher energy density. One of them is a nano-silicon anode for a lithium chemistry battery: , interesting lecture by SLAC.
That's nothing. 350Wh/kg is par for the course for lab-queen cells.
These primary cells, lithium-thionyl chloride chemistry, get 760Wh/kg:
http://www.varta-microbattery.com/applications/mb_data/documents/sales_literature_varta/handbook_primary_lithium_cylindrical_series_er_en.pdfIf you only need to use it once, you can do about 3 times as good as regular Lithium Ion batteries using this kind of chemistry. But I doubt they can discharge as quickly as some nice hobby LiPos.
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#433
by
c4fusion
on 17 Jan, 2016 05:15
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There are some fancy chemistry primary lithium batteries that get like 2-3x lithium ion energy density, but I'm not aware of anything that beats good LiPos for high power density.
Well maybe not power density, but there is a couple of semi commercial products that have higher energy density. One of them is a nano-silicon anode for a lithium chemistry battery: , interesting lecture by SLAC.
That's nothing. 350Wh/kg is par for the course for lab-queen cells.
These primary cells, lithium-thionyl chloride chemistry, get 760Wh/kg:
http://www.varta-microbattery.com/applications/mb_data/documents/sales_literature_varta/handbook_primary_lithium_cylindrical_series_er_en.pdf
If you only need to use it once, you can do about 3 times as good as regular Lithium Ion batteries using this kind of chemistry. But I doubt they can discharge as quickly as some nice hobby LiPos.
I guess what I am trying to say is that there might be some new batteries that are coming out within the year that might be better than LiPo
Cheers,
c4fusion
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#434
by
A_M_Swallow
on 17 Jan, 2016 05:21
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There are some fancy chemistry primary lithium batteries that get like 2-3x lithium ion energy density, but I'm not aware of anything that beats good LiPos for high power density.
Well maybe not power density, but there is a couple of semi commercial products that have higher energy density. One of them is a nano-silicon anode for a lithium chemistry battery: , interesting lecture by SLAC.
That's nothing. 350Wh/kg is par for the course for lab-queen cells.
These primary cells, lithium-thionyl chloride chemistry, get 760Wh/kg:
http://www.varta-microbattery.com/applications/mb_data/documents/sales_literature_varta/handbook_primary_lithium_cylindrical_series_er_en.pdf
If you only need to use it once, you can do about 3 times as good as regular Lithium Ion batteries using this kind of chemistry. But I doubt they can discharge as quickly as some nice hobby LiPos.
I guess what I am trying to say is that there might be some new batteries that are coming out within the year that might be better than LiPo
Cheers,
c4fusion
With 10 year development cycles the space community is slow to take on new technology. Also they do not like the risk of being the first to use something.
For about $200,000 a 1U cubesat to flight test the new batteries can be built and flown. If they work the manufacture can then claim TRL 9 status for his new batteries (and controller).
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#435
by
jamesh9000
on 20 Jan, 2016 07:47
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#436
by
acsawdey
on 20 Jan, 2016 14:19
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There are some fancy chemistry primary lithium batteries that get like 2-3x lithium ion energy density, but I'm not aware of anything that beats good LiPos for high power density.
Well maybe not power density, but there is a couple of semi commercial products that have higher energy density. One of them is a nano-silicon anode for a lithium chemistry battery: , interesting lecture by SLAC.
That's nothing. 350Wh/kg is par for the course for lab-queen cells.
These primary cells, lithium-thionyl chloride chemistry, get 760Wh/kg:
http://www.varta-microbattery.com/applications/mb_data/documents/sales_literature_varta/handbook_primary_lithium_cylindrical_series_er_en.pdf
If you only need to use it once, you can do about 3 times as good as regular Lithium Ion batteries using this kind of chemistry. But I doubt they can discharge as quickly as some nice hobby LiPos.
The discharge rate on these cells is nearly 3 orders of magnitude too low. My calculations based on what's been said about the power and energy needed for the Electron first stage pumps suggested you wanted cells with a discharge rate of 20-25C so that the power and energy needs would match, i.e. the battery is empty at the end of the first stage burn. This cell has a capacity of 1200mAh at a discharge rate of 1 mA, or 0.00083C. At 20 mA you get half capacity or 600mAh which is 0.033C. So this battery technology is completely unsuited to this use unless there is research that suggest the internal resistance can be radically reduced.
The thing is, you could go order a pile of LiPo cells from hobbyking and build a pack that would work for Electron. Sure, it's weight could be improved but it's not so bad that you lose all your payload. Then you can incrementally improve from there.
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#437
by
Katana
on 22 Jan, 2016 14:38
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20~25C makes perfect tradeoff between power density and energy density.
R/C hobby packs, motors, brushless controllers could be large. Multirotors and boats are large now . Customized products go larger.
In fact the bright color of motor on Rutherford looks popular in R/C hobby industry.
Without customization: Largest COTS brushless controllers i know includes Swordfish watercooled 12S (48V) 240A. Could use 12S(48V) 16000mAh packs and 10kw 1kg motors. This yields 500kgf thrust with 1.5MPa chamber pressure , low but useable. Assume pump efficiency 30%, isp 240s, isp vac 300s .
Use 304 stainless steel watertank for solar heater for propellant tanks. Thickness 0.31mm, diameter 360mm, length 0.5~2.5m each .
Use Soyuz rocket style 2 stages and a half configuration,10kg payload (6U cubesat ) to orbit (dv=10km/s) is possible .
Amateur launcher?
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#438
by
acsawdey
on 22 Jan, 2016 15:48
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Without customization: Largest COTS brushless controllers i know includes Swordfish watercooled 12S (48V) 240A. Could use 12S(48V) 16000mAh packs and 10kw 1kg motors. This yields 500kgf thrust with 1.5MPa chamber pressure , low but useable. Assume pump efficiency 30%, isp 240s, isp vac 300s .
Use 304 stainless steel watertank for solar heater for propellant tanks. Thickness 0.31mm, diameter 360mm, length 0.5~2.5m each .
Use Soyuz rocket style 2 stages and a half configuration,10kg payload (6U cubesat ) to orbit (dv=10km/s) is possible .
Amateur launcher?
All COTS parts would make sense for an amateur launcher. However it's not that hard to build bigger brushless motors, and if you hired a decent EE they could build you as big a controller as you need. There is a huge growth in expertise here due to hybrid and electric vehicles, and the need for high efficiency motors for appliances and industry. Heatsink the controllers to the LOX pump output pipe for cooling.
Is the 240/300 isp you estimate due to the low chamber pressure limiting how much sea level expansion you can have? Also this design seems well suited for a bunch of small chambers around a plug aerospike. Since you don't have a gas generator and power turbine to deal with, chance of RUD seems low if your engine controller regulates pump speed and shuts down if increased motor load indicates a pump failure in progress. With benign failure modes, you can use a lot of little engines to increase reliability.
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#439
by
Katana
on 22 Jan, 2016 23:04
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Without customization: Largest COTS brushless controllers i know includes Swordfish watercooled 12S (48V) 240A. Could use 12S(48V) 16000mAh packs and 10kw 1kg motors. This yields 500kgf thrust with 1.5MPa chamber pressure , low but useable. Assume pump efficiency 30%, isp 240s, isp vac 300s .
Use 304 stainless steel watertank for solar heater for propellant tanks. Thickness 0.31mm, diameter 360mm, length 0.5~2.5m each .
Use Soyuz rocket style 2 stages and a half configuration,10kg payload (6U cubesat ) to orbit (dv=10km/s) is possible .
Amateur launcher?
All COTS parts would make sense for an amateur launcher. However it's not that hard to build bigger brushless motors, and if you hired a decent EE they could build you as big a controller as you need. There is a huge growth in expertise here due to hybrid and electric vehicles, and the need for high efficiency motors for appliances and industry. Heatsink the controllers to the LOX pump output pipe for cooling.
Is the 240/300 isp you estimate due to the low chamber pressure limiting how much sea level expansion you can have? Also this design seems well suited for a bunch of small chambers around a plug aerospike. Since you don't have a gas generator and power turbine to deal with, chance of RUD seems low if your engine controller regulates pump speed and shuts down if increased motor load indicates a pump failure in progress. With benign failure modes, you can use a lot of little engines to increase reliability.
240/300 isp come from different version of sl / vacuum noozles, conventional. It's not worthy to develop plug noozle in such a small but multidisciplinary project. Keep everything simple.
Decent EE on this power level is industrial conventional but hard (myself worked on E vehicles for years). And the controller project maybe more slow and expensive than the engine project itself. Typically controllers RUD everyday during development.
So it's better to spend decent knowledge on choose and TEST reliable COTS, until big big funding enable do everything inhouse.
The difficulty of rocketary are similar to car industry on every aspects, SpaceX and Tesla. Things typical to industry are huge for startup companies.
"Amateur launcher "with amateur COTS really need money typical to business startups. Indeed business startups of other industry do use amateur COTS, arduino, etc.
