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The New Space Race

 

BBC weighs in on the companies competing to lower the cost of space access, including one from New Zealand I hadn't heard of.

http://www.bbc.co.uk/news/resources/idt-sh/disruptors_the_new_space_race?ocid=gnl.email.banner.bbc-gnl..disruptorsep1_

bob Waldrop, Okie City

markus baur
 

Am 06.10.2017 um 16:55 schrieb Bob Waldrop:
BBC weighs in on the companies competing to lower the cost of space access, including one from New Zealand I hadn't heard of.
http://www.bbc.co.uk/news/resources/idt-sh/disruptors_the_new_space_race?ocid=gnl.email.banner.bbc-gnl..disruptorsep1_
the new zealand team is interesting - they developed a rather unique engine, that would have been impossible only a few years ago

https://en.wikipedia.org/wiki/Rutherford_(rocket_engine)

lithium batteries into space!

servus

markus

bob Waldrop, Okie City


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Tarl Neustaedter
 

On 2017-Oct-6 11:04 , markus baur wrote:
[...]
the new zealand team is interesting - they developed a rather unique engine, that would have been impossible only a few years ago

https://en.wikipedia.org/wiki/Rutherford_(rocket_engine)

lithium batteries into space!
[...]. The first stage battery, which has to power the pumps of nine engines simultaneously, can provide over 1 MW of electric power.
Wow.  Serious lithium batteries! Although, given that this needs to run at such high power for only a couple of minutes, I wonder if supercaps might be a better container for that kind of energy.

markus baur
 

Am 06.10.2017 um 17:34 schrieb Tarl Neustaedter:
On 2017-Oct-6 11:04 , markus baur wrote:
[...]
the new zealand team is interesting - they developed a rather unique engine, that would have been impossible only a few years ago

https://en.wikipedia.org/wiki/Rutherford_(rocket_engine)

lithium batteries into space!
[...]. The first stage battery, which has to power the pumps of nine
engines simultaneously, can provide over 1 MW of electric power.
Wow.  Serious lithium batteries! Although, given that this needs to run at such high power for only a couple of minutes, I wonder if supercaps might be a better container for that kind of energy.
i THINK this is supposed to mean 1 MWh - if i find the time i will chase down the reference and maker an edit to wikipedia

the pump has two electric motors, with 50 hp each - 1 hp is about 0,7 kw - so electric power should be something around 70 kW .. so something does not fit

servus

markus


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Tarl Neustaedter
 

On 2017-Oct-6 11:42 , markus baur wrote:

    [...]. The first stage battery, which has to power the pumps of nine
    engines simultaneously, can provide over 1 MW of electric power.

Wow.  Serious lithium batteries! Although, given that this needs to run at such high power for only a couple of minutes, I wonder if supercaps might be a better container for that kind of energy.

i THINK this is supposed to mean 1 MWh - if i find the time i will chase down the reference and maker an edit to wikipedia

the pump has two electric motors, with 50 hp each - 1 hp is about 0,7 kw - so electric power should be something around 70 kW .. so something does not fit

That would make considerably more sense, and makes it less extreme than my original guess. 1 MWh discharged in five minutes (order of magnitude of main engine firing duration) is about 83 kW, which matches your number.

Given that the amount of energy stored seems to be the driving factor, rather than discharge rate, it's probably lithium batteries, not supercaps.

https://en.wikipedia.org/wiki/Supercapacitor#Comparison_with_other_storage_technologies

Although, lithium batteries to hold a MWh probably mass around 4 tons(!). Mass of supercaps to hold that much energy would be even larger.

markus baur
 

Am 06.10.2017 um 18:08 schrieb Tarl Neustaedter:
On 2017-Oct-6 11:42 , markus baur wrote:

    [...]. The first stage battery, which has to power the pumps of nine
    engines simultaneously, can provide over 1 MW of electric power.

Wow.  Serious lithium batteries! Although, given that this needs to run at such high power for only a couple of minutes, I wonder if supercaps might be a better container for that kind of energy.
i THINK this is supposed to mean 1 MWh - if i find the time i will chase down the reference and maker an edit to wikipedia

the pump has two electric motors, with 50 hp each - 1 hp is about 0,7 kw - so electric power should be something around 70 kW .. so something does not fit
That would make considerably more sense, and makes it less extreme than my original guess. 1 MWh discharged in five minutes (order of magnitude of main engine firing duration) is about 83 kW, which matches your number.
still there is something squirely going on .. i have a few things to finish first, then will start chasing this down ..

servus

markus

Given that the amount of energy stored seems to be the driving factor, rather than discharge rate, it's probably lithium batteries, not supercaps.
https://en.wikipedia.org/wiki/Supercapacitor#Comparison_with_other_storage_technologies
Although, lithium batteries to hold a MWh probably mass around 4 tons(!). Mass of supercaps to hold that much energy would be even larger.

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Tarl Neustaedter
 

On 2017-Oct-6 12:21 , markus baur wrote:

That would make considerably more sense, and makes it less extreme than my original guess. 1 MWh discharged in five minutes (order of magnitude of main engine firing duration) is about 83 kW, which matches your number.

still there is something squirely going on .. i have a few things to finish first, then will start chasing this down ..

Yeah. My calculation is off, too - I drifted in the wrong direction. 70 kW * 300 seconds = 21 MJ. That's ~6 kWh, not MWh.

markus baur
 

Am 06.10.2017 um 18:25 schrieb Tarl Neustaedter:
On 2017-Oct-6 12:21 , markus baur wrote:

That would make considerably more sense, and makes it less extreme than my original guess. 1 MWh discharged in five minutes (order of magnitude of main engine firing duration) is about 83 kW, which matches your number.
still there is something squirely going on .. i have a few things to finish first, then will start chasing this down ..
Yeah. My calculation is off, too - I drifted in the wrong direction. 70 kW * 300 seconds = 21 MJ. That's ~6 kWh, not MWh.
ok - getting some good data - and its still a mystery

burn time for first stage is 161 seconds - pump power is 2 * 37 kw * 165 seconds is 12210 kWs or 12,210 MWs / 3,4 kWh

http://www.b14643.de/Spacerockets_1/Rest_World/Electron-NLV/Propulsion/engines.htm

the battery pack is for all 9 first stage engines together!

https://web.archive.org/web/20160920143833/http://usgif.org/system/uploads/4606/original/ROCKET_LAB_INTRO_USGIF.pdf

scroll down

9 * 12,21 = 109, 9 MWs - divided by 3600 this gives 0,03 MWh total energy / 31 kWh (and thats a much more reasonable size and weight)

power however = 9 * 2 * 37 = 666 kW .. which is getting close to the stated 1 MW of power ..

especially if we add losses some for less then perfect power and controller electronics (for example, i dont think they really cool the power electronics very much in order to save weight - and hot electronics run inefficient)

servus

markus




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Email from my mobile connection.

Tarl Neustaedter
 

On 2017-Oct-6 15:18 , markus baur wrote:
[...]
9 * 12,21 = 109, 9 MWs - divided by 3600 this gives 0,03 MWh total
energy / 31 kWh (and thats a much more reasonable size and weight)

power however = 9 * 2 * 37 = 666 kW .. which is getting close to the
stated 1 MW of power ..

especially if we add losses some for less then perfect power and
controller electronics (for example, i dont think they really cool the
power electronics very much in order to save weight - and hot
electronics run inefficient)

O.k. - 31 kWh will require a bit over 100 kg of lithium batteries. But
that will only give you 175 kW power rate. Which means they'd need more
like 450-500 kg of batteries, to get the discharge rate they need.

LiIon supercaps would take about 2000 kilograms to hold the required 31
kWh, and they would easily support the discharge rate required.

So the tradeoff still favors batteries rather than supercaps. I suspect
they're pushing the batteries to higher discharge rates than generally
documented by adding conductors and vastly reducing battery life, so
they can reduce the mass of the batteries needed.

markus baur
 

Am 06.10.2017 um 23:31 schrieb Tarl Neustaedter:
On 2017-Oct-6 15:18 , markus baur wrote:
[...]
9 * 12,21 = 109, 9 MWs - divided by 3600 this gives 0,03 MWh total
energy / 31 kWh (and thats a much more reasonable size and weight)

power however = 9 * 2 * 37 = 666 kW .. which is getting close to the
stated 1 MW of power ..

especially if we add losses some for less then perfect power and
controller electronics (for example, i dont think they really cool the
power electronics very much in order to save weight - and hot
electronics run inefficient)
O.k. - 31 kWh will require a bit over 100 kg of lithium batteries. But
that will only give you 175 kW power rate. Which means they'd need more
like 450-500 kg of batteries, to get the discharge rate they need.
sounds correct ...

LiIon supercaps would take about 2000 kilograms to hold the required 31
kWh, and they would easily support the discharge rate required.
So the tradeoff still favors batteries rather than supercaps. I suspect
they're pushing the batteries to higher discharge rates than generally
documented by adding conductors and vastly reducing battery life, so
they can reduce the mass of the batteries needed.
essentially they need two certifiable live cycles out of the batteries (static fire test and flight) - so they will probably design the battery pack to have a design life of about 20 to 25 cycles

servus

markus




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Marvin Carlson
 

The cost of rockets is far too high and the reason, in my opinion is the players have had too much money to think clearly of less expensive alternatives.  This is a big example of governments getting involved and stifling advancement.

On 10/06/2017 09:55 AM, Bob Waldrop wrote:
BBC weighs in on the companies competing to lower the cost of space access, including one from New Zealand I hadn't heard of.

http://www.bbc.co.uk/news/resources/idt-sh/disruptors_the_new_space_race?ocid=gnl.email.banner.bbc-gnl..disruptorsep1_

bob Waldrop, Okie City



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