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).
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.
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…
Quote from: douglas100 on 01/26/2018 06:02 pmOn 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.
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?
Quote from: Stan-1967 on 01/26/2018 07:31 pmQuote from: douglas100 on 01/26/2018 06:02 pmOn 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?
I remember @Peter_J_Beck mentioned this as an advantage of electric turbo pumps, they can run the tanks dry if need be.
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.
What are the things you really need to manage to be able to run your propellant tanks dry?
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
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)
Additionally, simply running to depletion will give a variable and unpredictable final velocity vector, spoiling accuracy. Which is no way to get a bullseye...
@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?)
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.
QuoteWe 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/1202726456855367682Quote Additionally, simply running to depletion will give a variable and unpredictable final velocity vector, spoiling accuracy. Which is no way to get a bullseye...
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.
Quote from: FutureSpaceTourist on 12/06/2019 05:29 amQuoteWe 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/1202726456855367682Quote 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.
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).
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.
Quote from: TrevorMonty on 05/03/2020 02:35 amElectron 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).
drivIf the pump is still powered when it starts trying to pump tank fumes the sudden reduction of load will let it accelerate
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.
Another set of 3D printed Rutherford engines rolling off the line in Long Beach. We're fast approaching our 200th engine!