Author Topic: RocketLab Electron Smallsat Launcher  (Read 738476 times)

Offline TrevorMonty

Re: RocketLab Electron Smallsat Launcher
« Reply #1440 on: 12/16/2018 07:18 am »
While we coast, investigation has revealed that a large adult sheep masses about 160 kg. It is 180 cm long and stands 127 cm at the shoulder, with about 50 cm of that height being the legs. The Electron can carry 220 kg to orbit and has a fairing that is 100 cm in diameter and 191 cm long, including the forward taper. Though payload interfaces would need to be designed, it would appear Electron has SSTO capability (Single Sheep to Orbit).
Luckily for the sheep RL don't launch meat.
 

Offline Lars-J

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Re: RocketLab Electron Smallsat Launcher
« Reply #1441 on: 12/17/2018 04:46 pm »
Now that Electron seems to be a working and reliable launcher (so far) - perhaps it and SpaceX's F9 should give other launch providers a template going forward to developing new launch vehicles. Electron and F9 do after all share some things that would appear to be useful 'good practices' for others to adopt: (and no, not 9 engines specifically) ;)

 - several engines on first stage (smaller engines less costly to develop)
 - upper stage has vacuum version of first stage engine (saves money)
 - same diameter on both stages (saves money by simplifying tooling)

Sure, this approach won't work for all. But it is amazing that only SpaceX and RocketLab so far are doing this.

Offline envy887

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Re: RocketLab Electron Smallsat Launcher
« Reply #1442 on: 12/17/2018 06:27 pm »
Now that Electron seems to be a working and reliable launcher (so far) - perhaps it and SpaceX's F9 should give other launch providers a template going forward to developing new launch vehicles. Electron and F9 do after all share some things that would appear to be useful 'good practices' for others to adopt: (and no, not 9 engines specifically) ;)

 - several engines on first stage (smaller engines less costly to develop)
 - upper stage has vacuum version of first stage engine (saves money)
 - same diameter on both stages (saves money by simplifying tooling)

Sure, this approach won't work for all. But it is amazing that only SpaceX and RocketLab so far are doing this.

Blue was going to do all those with New Glenn, but dropped the common upper stage engine. They still are doing the other 2 things.

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Re: RocketLab Electron Smallsat Launcher
« Reply #1443 on: 03/23/2019 07:05 am »
https://twitter.com/rocketlab/status/1109216668608192512

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We don't just go to orbit, we deploy satellites with exquisite accuracy. Electron's Kick Stage takes our customers' satellites exactly where they need to go. Looking forward to flying another Kick Stage on our @DARPA #R3D2 mission. L-2 days!
rocketlabusa.com/vehicle/kickst…

Offline TrevorMonty

Re: RocketLab Electron Smallsat Launcher
« Reply #1444 on: 03/29/2019 02:25 am »


https://www.forbes.com/sites/jonathanocallaghan/2019/03/28/rocket-lab-launches-experimental-satellite-for-darpa-on-its-first-mission-of-2019/#50084c08d0c0

"We’re at a count of 117 stored launch vehicles now in some form of development,” said Beck. “We’ve doubled in size in the last six months, and most of that is really building the business.”

That 117 could be varies parts eg engines, valves, avionics, doubt its stages.

Offline Stan-1967

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Re: RocketLab Electron Smallsat Launcher
« Reply #1445 on: 04/09/2019 02:32 am »
Rocketlab has a new users guide as of April 2019.  Linking to it here:
https://www.rocketlabusa.com/assets/Uploads/Rocket-Lab-Payload-Users-Guide-7.3.pdf

Good info on the kick stage & the "Photon" spacecraft platform.
« Last Edit: 04/09/2019 03:00 am by gongora »

Offline Comga

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Re: RocketLab Electron Smallsat Launcher
« Reply #1446 on: 04/09/2019 05:06 pm »
On the point about the thermal control of the payload, Electron doesn't seem to have aircon going to the fairing. Anyone know if this is the case?

Rocketlab's Electron User guide ( see page 14) says the fairing can have environmental controls, although presence of this feature seems to be payload specific. 

The link on Rocketlab's website to the current Version 6.2 of the Electron Payload User's Guide is broken, possibly by intention.

Has anyone downloaded any revisions after the December 2016 Version 4.0 attached to the above post?
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline edkyle99

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Re: RocketLab Electron Smallsat Launcher
« Reply #1447 on: 04/09/2019 05:29 pm »
On the point about the thermal control of the payload, Electron doesn't seem to have aircon going to the fairing. Anyone know if this is the case?

Rocketlab's Electron User guide ( see page 14) says the fairing can have environmental controls, although presence of this feature seems to be payload specific. 

The link on Rocketlab's website to the current Version 6.2 of the Electron Payload User's Guide is broken, possibly by intention.

Has anyone downloaded any revisions after the December 2016 Version 4.0 attached to the above post?
Here's 6.2

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Re: RocketLab Electron Smallsat Launcher
« Reply #1448 on: 12/06/2019 05:29 am »
twitter.com/simplyspace_yt/status/1202628705484337152

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I remember @Peter_J_Beck mentioned this as an advantage of electric turbo pumps, they can run the tanks dry if need be.

https://twitter.com/peter_j_beck/status/1202679301562257408

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This is correct, stage 1 is burnt to depletion. On a small launch vehicle residuals can easly dwarf the payload lift capacity. 150L of left over propellants is our total payload, so it’s super important to have good propellant management.

https://twitter.com/_david_011/status/1202681382687952896

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What are the things you really need to manage to be able to run your propellant tanks dry?

twitter.com/torybruno/status/1202724197589377025

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One can always run one’s tanks dry, ending up with more of whatever parameter was in the last burn. Atlas and Delta are far more sophisticated. They can dynamicly measure performance during burn and reprogram the overall trajectory to provide more of a predetermined orbital state

https://twitter.com/peter_j_beck/status/1202826463956717568

Quote
We have the same dynamic measurement approach on ascent. ULA absolutely set the gold standard for orbital accuracy and now Electron is delivering this accuracy for small satellites. (Within 400 meters on apogee last flight)

https://twitter.com/torybruno/status/1202726456855367682

Quote
Additionally, simply running to depletion will give a variable and unpredictable final velocity vector, spoiling accuracy. Which is no way to get a bullseye...

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Re: RocketLab Electron Smallsat Launcher
« Reply #1449 on: 04/25/2020 06:25 am »
twitter.com/maxstricht/status/1253748605107798020

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@Peter_J_Beck Why not coat electron so the ice doesn't stick, so you would get better preformance?

(And so we get to see a black rocket fly?)

https://twitter.com/peter_j_beck/status/1253767191930925056

Quote
The ice is actually helpful as it acts as a thermal insulator and allows us to maintain cooler LOX. Also, coating the tanks is another production process and right now not having to paint the whole Rocket is wonderful.


Offline john smith 19

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Re: RocketLab Electron Smallsat Launcher
« Reply #1451 on: 05/02/2020 07:02 am »

Quote
We have the same dynamic measurement approach on ascent. ULA absolutely set the gold standard for orbital accuracy and now Electron is delivering this accuracy for small satellites. (Within 400 meters on apogee last flight)

https://twitter.com/torybruno/status/1202726456855367682

Quote
Additionally, simply running to depletion will give a variable and unpredictable final velocity vector, spoiling accuracy. Which is no way to get a bullseye...
Actually both statements are true.

In principle a more controlled booster burn means a more precise US burn and hence a narrower spread of altitude/inclination/velocity ranges.

But if you're goals include first stage recovery and its a small stage then burn to completion is an excellent strategy. It gives maximum margin for the US (unless the booster was loaded with below minimum propellant levels, which would be very poor pad operations). 

So the US GNC might need to be more precise and the processor work harder to calculate exactly what the stage has to do cope with such a wider dispersion.

In the days when a flight processor could weigh a 100lb and a few 100 KIPS this was a serious trade off which should not be taken lightly.  :(

Things have moved on a bit since then.  :) The only real question would be if the INS has the necessary accuracy and update rate and the TVC actuators the necessary authority to command the vehicle if the booster performance was borderline viable. I'm not familiar enough with the SoA. My instinct is this is one of those "could be" problems if you choose absolutely rock bottom grade sensors and actuators, but disappears if you buy slightly up the capability scale.

The complaint would be "But we'll have to load the US heavy to cope with worst case performance of the booster."
Umm, don't you do this anyway? Especially if like ULA you put a premium on mission success. Likewise AFAIK propellant biasing (where you load a bit more of the lighter propellant to ensure the heavier one always burns out first, pushing maximum reaction mass out the back) is SOP for all liquid propellant rockets.

This has been a known thing since Longsdon's and Africano's classic paper on the subject.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Steven Pietrobon

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Re: RocketLab Electron Smallsat Launcher
« Reply #1452 on: 05/03/2020 12:52 am »
Likewise AFAIK propellant biasing (where you load a bit more of the lighter propellant to ensure the heavier one always burns out first, pushing maximum reaction mass out the back) is SOP for all liquid propellant rockets.

I believe the reason for fuel biasing is so that you don't run the engine oxidiser rich (which would subsequently result in the metal in your engine burning) when the fuel runs out. It just so happens that most propellant combinations have an oxidiser to fuel ratio greater than one. Fun fact! Liquid fluorine and HTP has a mixture ratio less than one (0.88).
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline TrevorMonty

Re: RocketLab Electron Smallsat Launcher
« Reply #1453 on: 05/03/2020 02:35 am »

Quote
We have the same dynamic measurement approach on ascent. ULA absolutely set the gold standard for orbital accuracy and now Electron is delivering this accuracy for small satellites. (Within 400 meters on apogee last flight)

https://twitter.com/torybruno/status/1202726456855367682

Quote
Additionally, simply running to depletion will give a variable and unpredictable final velocity vector, spoiling accuracy. Which is no way to get a bullseye...
Actually both statements are true.

In principle a more controlled booster burn means a more precise US burn and hence a narrower spread of altitude/inclination/velocity ranges.

But if you're goals include first stage recovery and its a small stage then burn to completion is an excellent strategy. It gives maximum margin for the US (unless the booster was loaded with below minimum propellant levels, which would be very poor pad operations). 

So the US GNC might need to be more precise and the processor work harder to calculate exactly what the stage has to do cope with such a wider dispersion.

In the days when a flight processor could weigh a 100lb and a few 100 KIPS this was a serious trade off which should not be taken lightly.  :(

Things have moved on a bit since then.  :) The only real question would be if the INS has the necessary accuracy and update rate and the TVC actuators the necessary authority to command the vehicle if the booster performance was borderline viable. I'm not familiar enough with the SoA. My instinct is this is one of those "could be" problems if you choose absolutely rock bottom grade sensors and actuators, but disappears if you buy slightly up the capability scale.

The complaint would be "But we'll have to load the US heavy to cope with worst case performance of the booster."
Umm, don't you do this anyway? Especially if like ULA you put a premium on mission success. Likewise AFAIK propellant biasing (where you load a bit more of the lighter propellant to ensure the heavier one always burns out first, pushing maximum reaction mass out the back) is SOP for all liquid propellant rockets.

This has been a known thing since Longsdon's and Africano's classic paper on the subject.
When Photon is being used, 2nd stage orbit insertion doesn't need to be perfect as Photon can correct for it. Any smallsat that doesn't use Photon will have DV to do its own orbit correction as it will be deployed to 2nd stage disposal orbit.

With ULA Centuar   is doing final payload deployment so its more critical.

Electron can run its tanks dry as electric pumps can react instantly when it detects no fuel. I don't think same can be said for turbopumps, hence need to keep little unburnt fuel.
« Last Edit: 05/03/2020 02:36 am by TrevorMonty »

Offline john smith 19

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Re: RocketLab Electron Smallsat Launcher
« Reply #1454 on: 05/03/2020 07:17 am »
I believe the reason for fuel biasing is so that you don't run the engine oxidiser rich (which would subsequently result in the metal in your engine burning) when the fuel runs out. It just so happens that most propellant combinations have an oxidiser to fuel ratio greater than one. Fun fact! Liquid fluorine and HTP has a mixture ratio less than one (0.88).
That's true for Shuttle but IIRC the Longsdon & Africano paper (one of my favorites, but missing one vital piece) the goal is normally to maximize pay. Given all vehicles to date were expendable not destroying the engine after it's served its purpose does not seem a high priority.

So the logic says burn till oxidizer depletion.  TBH This looks like another piece of rocket industry folklore.

It always fascinated me that Aerojet often pitched huge O/F ratio changes in their engine designs. It might be because they never expected them to be built but equally it could be they knew that
Maximum chamber temp --> stochiometric O/F ratio.

Chamber temp drops either side of that.

So if the rate of change of O/F ratio is fast enough T(chamb) spikes briefly then starts dropping again.
Indeed could a big enough chamber have so much thermal inertia in it that any actual spike is absorbed by the gas already in the chamber?

Obviously this idea's not viable in an era of manually adjusted test chamber settings, but once those are set by electrically controlled valves....
Like wise there's a lot of caveats to the meaning of "fast enough" especially WRT combustion instability.
The flip side to this is the "Most reliable component is the one that is not there" argument.
« Last Edit: 05/03/2020 07:19 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline john smith 19

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Re: RocketLab Electron Smallsat Launcher
« Reply #1455 on: 05/03/2020 07:29 am »
Electron can run its tanks dry as electric pumps can react instantly when it detects no fuel. I don't think same can be said for turbopumps, hence need to keep little unburnt fuel.
They are both mechanical systems and so are subject to inertia.

There are 2 issues.

If the pump is still powered when it starts trying to pump tank fumes the sudden reduction of load will let it accelerate, probably to the point at which parts start to fly off.  An electric pump replaces a gas turbine with a motor but they are still a spinning lump of metal. OTOH the electric motor can act as a generator to dummy load, so (in principle) could brake much faster.

The other issue is if the chamber burns oxidizer rich that leaves free O2 in the chamber which is probably hot enough to start the chamber burning.

The easy course of action is to ensure the MR never goes Ox rich (or more specifically to the point it exactly matches the fuel, which is the maximum temperature burn).
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline TrevorMonty

Re: RocketLab Electron Smallsat Launcher
« Reply #1456 on: 05/03/2020 09:24 am »
Electron can run its tanks dry as electric pumps can react instantly when it detects no fuel. I don't think same can be said for turbopumps, hence need to keep little unburnt fuel.
They are both mechanical systems and so are subject to inertia.

There are 2 issues.

If the pump is still powered when it starts trying to pump tank fumes the sudden reduction of load will let it accelerate, probably to the point at which parts start to fly off.  An electric pump replaces a gas turbine with a motor but they are still a spinning lump of metal. OTOH the electric motor can act as a generator to dummy load, so (in principle) could brake much faster.

The other issue is if the chamber burns oxidizer rich that leaves free O2 in the chamber which is probably hot enough to start the chamber burning.

The easy course of action is to ensure the MR never goes Ox rich (or more specifically to the point it exactly matches the fuel, which is the maximum temperature burn).
The no fuel detection would be up stream enough to give pump enough time to stop.

Offline Barley

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Re: RocketLab Electron Smallsat Launcher
« Reply #1457 on: 05/04/2020 01:48 am »
driv
If the pump is still powered when it starts trying to pump tank fumes the sudden reduction of load will let it accelerate
Not with an electronically controlled motor.  The motor speed is limited by the frequency of the drive current.  Depending on the exact type of motor the drive frequency is the same as the operating speed, or a few percent higher.  So speed cannot surge much.  The only way for the motor to speed up significantly is for the motor controller to increase the frequency, and that won't happen as a result of physics, since it's controlled by software and control rules.

What happens is as the mechanical load is removed the back emf from the motor drops and the current rises, potentially high enough to melt the motor or controller, but the controller is already switching at kilohertz or higher and can react very quickly to cut the voltage and limit current to prevent damage.

Offline john smith 19

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Re: RocketLab Electron Smallsat Launcher
« Reply #1458 on: 05/06/2020 06:00 am »
What happens is as the mechanical load is removed the back emf from the motor drops and the current rises, potentially high enough to melt the motor or controller, but the controller is already switching at kilohertz or higher and can react very quickly to cut the voltage and limit current to prevent damage.
There's lots of ifs, buts and maybe's in there.

Eletron is a small laucher, so pipe runs are short. Those pumps are in the 10s of 1000s of RPM range. I'm aware of the theory  of what should happen but for something like this I'd want a rig test to prove it.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

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Re: RocketLab Electron Smallsat Launcher
« Reply #1459 on: 05/13/2020 11:37 pm »
https://twitter.com/rocketlab/status/1260710472820523009

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Another set of 3D printed Rutherford engines rolling off the line in Long Beach. We're fast approaching our 200th engine!

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