CS Looking at Electric Pumps

I have to be a little picky with this video, the masses given comparing pressure fed to electric fed could have been more detailed. In amongst those numbers, I assume is battery weight which would have been nice to know.
If they intend to use Li-Pos and if they want to reuse these they can only really go down to 3.0 volts per cell, or else damage occurs. Others using Li-Pos to power pumps I have heard go down to 2.8 volts per cell, but as this is in an expendable rocket, it does not matter as much. So a bit more care and extra battery capacity may be required to be able to operate safely, which is, of course, more weight.

There is also no deltaV comparison, which is really the only important number you are designing for when trying to reach space, in this case, 105 km altitude.

Where,
Δv = Velocity change (deltaV)
Isp = specific impulse
g0 = gravity
m0 = Initial mass (with propellant)
mf = Final mass (without propellant)

The comparison also does not state the chamber pressure of the engine, I assume the electric comparison uses the same chamber pressure as the pressure fed. But as stated, the whole point of a pump is to decrease your tank mass and increase engine chamber pressure which in turn increases your engine Isp, your deltaV and decreases engine mass (theoretically). The question then is, what chamber pressure can you reliably design and manufacture for?
One must take into account the higher heat flux and added cooling requirements also.

The COTS or common of the shelf components I have to also argue, you are never going to be able to buy a pump off the shelf that will match your mass flow and pressure requirements, let alone material compatibility. Electric motors and speed controllers you may be able to, which will speed up development, but you will probably have to make modifications to make these flight-ready anyhow.

All in all, I can definitely see the advantages of looking into this pumping method for such a project, and it is great they are open to it.
I just wish the video lived up to its name more as we do not really get a good comparison between the two systems.

Copenhagen Suborbitals: Year in Review 2019

Video Caption: Our rockets are 100% crowdfunded. Visit http://www.copsub.com/support-us to become one of our supporters!
Compliment us by wearing our apparel:
https://www.zazzle.com/store/copsub Book a visit for our rocket factory in Copenhagen: https://www.airbnb.com/copsub

Copenhagen Suborbitals is the world’s only manned, crowdfunded space program. In the future, a volunteer astronaut will fly to space on our home-built rocket. We do this on our spare time, all the donations go to paying our workshop rent and buying materials. We are forever thankful to each of our supporters!

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Copenhagen Suborbitals: 1/10th Scale Capsule Testing

Video Caption: Our rockets are 100% crowdfunded. Visit http://www.copsub.com/support-us to become one of our supporters!
Compliment us by wearing our apparel: https://www.zazzle.com/store/copsub Book a visit for our rocket factory in Copenhagen: https://www.airbnb.com/copsub

Copenhagen Suborbitals is the world’s only manned, crowdfunded space program. In the future, a volunteer astronaut will fly to space on our home-built rocket. We do this on our spare time, so all your donations go to paying our workshop rent and buying materials. You are the biggest part of this project and we are forever thankful to each of our supporters!

In this video we take you with us on some small preparations for our upcoming 1:10th scale Spica space capsule splashdown tests which will give us some real world data to compare with our landing simulations. This will put us on track for a safe landing of our homemade space capsule and volunteer astronaut when coming back from space.

CS: Building Spica’s Inter-tank Section

Video Caption: Our rockets are 100% crowdfunded. Visit http://www.copsub.com/support-us to become one of our supporters! Compliment us by wearing our apparel: https://www.zazzle.com/store/copsub Book a visit for our rocket factory in Copenhagen: https://www.airbnb.com/copsub

The production of Spica – the largest crowdfunded, amateur space rocket has begun. After cutting all the parts for it on our homemade CNC plasma cutter and rolling the stainless steel hull we begin to weld all the pieces together for an inter tank section that will bridge the liquid oxygen and ethanol propellant tanks which will feed our DIY bi-liquid rocket engine. The world’s first crowdfunded crewed launch vehicle is on it’s way!

Copenhagen Suborbitals is the world’s only manned, crowdfunded space program. In the future, a volunteer astronaut will fly to space on our home-built rocket. We do this on our spare time, all the donations go to paying our workshop rent and buying materials.

We are forever thankful to each of our supporters!
Twitter : https://twitter.com/CopSub
Facebook : https://www.facebook.com/CopenhagenSu…
Instagram : https://www.instagram.com/copsub/
LinkedIn : https://www.linkedin.com/company/cope…
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Music: “All Systems Nominal” and “Moon Dance” by Everyday Astronaut: (https://www.everydayastronaut.com)
Percussion elements by Eric Taylor: (https://twitter.com/EricTaylorF_L) “Twisted” by Kevin MacLeod (https://incompetech.com)