My background is in aerospace and while I’m not an expert on COPVs, I’m familiar with their design. Carbon fiber overwrap is really good for internal pressure applications or in other words, the typical pressure vessel due to carbon fiber’s very high tensile strength. Think of those videos where folks put rubber bands on watermelons to make them explode; the concept is similar to a COPV in that the rubber bands (carbon fiber) “compress” the watermelon (pressure vessel) to “contain” the pressure. COPVs can take high internal pressures of 6000 PSI (which is the same internal pressure of the ISS NORS tank used to recharge oxygen and nitrogen on the ISS and coincidentally is the same *external* pressure experienced at the depths of the Titanic. (Some helium bottles have higher internal pressure). While in aerospace applications there are some load cases where the COPV has an external pressure load on them like a helium bottle stored in a propellant tank on a SpaceX Falcon 9, those pressures are nowhere near deep sea pressures.
The reason why I don’t think COPVs are a good design for an external pressure application is the load direction; carbon fiber tow doesn’t really do well maintaining an external load. Think back to the watermelon example; apply an increased external pressure and the rubber bands really don’t help with withstanding that increased pressure.
Carbon fiber itself is very difficult to verify that you have the correct properties once they're wound onto the tank. The properties are anisotropic meaning depending on the direction of the fiber you’re gonna get different mechanical properties. Defects like delamination (when a wind unwraps) or voids between the tank wall and fiber are common if you don’t have a qualified winding operation and really really good procedures. In short, while not needing software, repeatability in manufacturing a COPV is incredibly difficult. Part of the reason SpaceX switched to metal tanks is that the mechanical properties of stainless actually increase in a cryogenic environment so there’s an added benefit.
In 2016, SpaceX’s Falcon 9 carrying AMOS-6 exploded during a routine static fire due to a buckled liner of a COPV on the 2nd stage LOX tank. The liner buckled which created a void between the liner and the fiber overwrap which then developed solid oxygen (or an ingress of LOX) that initiated an explosion due to friction. Falcon 9 had been flying for 6 years at that point so I’d consider that a pretty mature or at least an “operational” vehicle so for it to explode on the pad like that is how tricky COPVs can be.
One of my first startup ideas I pitched to YC was to deorbit the inactive LEO satellites/debris as as service utilizing kilowatt-class lasers utilize radiation pressure to degrade the orbit enough to let atmospheric drag take care of the rest.
Well due to (IIRC) the Outer Space Treaty, spacecraft launched is still owned by their original company and I dont think the original company, or anyone else for that matter wants to pay to cleanup their trash, therefore no market.
Didn't get interviewed for most likely that reason.
We decided against launching them because the laser would have a limited power supply and could only deorbit X amount of debris before completely depleting its power supply; something solar panels can't effectively recharge (well you'd need A LOT of them). Combine that with cost for launch, it gets pretty expensive to deorbit only a few satellites.
Because of this we went with surface based lasers; they could be recharged using the local grid and clean a specific section of the sky. We looked at placing lasers at locations with high altitude and cross referenced them with the local $ per kilowatt hour. Never really got to the stage of deciding where to place one since we were still stuck with figuring out the market for it. I guess someones active satellite needs to get Sandra Bullocked by some old debris before we start going "hey. there's a market for cleanup!".
The ISS is currently looking into a laser system to clean up debris if i remember correctly. I guess if they ever figure out the person who uses it would get to call him/herself "ISS Door Gunner"
Pitch: We're ATLAS, we plan to launch extremely small cubesat payloads (x<100kg) into low earth orbit on demand.
1) How much calculations/numbers crunched would we need to convince angels to invest? Rockets of this size aren't something we can bootstrap without a little financial support.
More Background:
Right now, the only way to get a cubesat into orbit is by ridesharing on bigger rockets as a secondary payload. The problem with this is they're not assured to reach a preferred orbit and are at the mercy of the scheduling of the primary payloads. NASA currently has a backlog of ~50 cubesats that need to get into orbit, as well as the many upcoming launches (including SpX this Sunday). We are currently working on the RFP for the Venture Class Launch Service however we may not have the resources to fully complete it by the deadline (13 July). We plan to market this service to Universities as well as hobbyists and government space agencies.
I think one of the challenges is that there is usually extra capacity to the ISS, and so you at least initially you need to compete on convenience not money (by the way, I should note that we funded Bagaveev in the last YC batch).
The most convincing thing to investors will be an order book--ie, go convince people in that backlog to say they will pay you a certain amount for future launches if you can build a reliable rocket. If you have that plus credible initial technical development you can probably raise some money.
> He urged the Air Force's Space and Missiles Systems Center to "embrace SpaceX innovation and practices," while SpaceX needed to understand the Air Force's need to mitigate risks, and be more open to benefiting from the government's experience.
I found this to be the most important point in the entire article because I'm sure the USAF is very "old guard" with a mentality of "if it isn't broken don't fix it" while on the other hand, SpaceX is the new kid on the block with the newest and coolest tech
I did my undergraduate capstone class on the Kessler Syndrome. UNCOPUOS, the United Nations Committee on the Peaceful Uses of Outer Space dictate that a satellite must deorbit itself within 25 years after mission completion.
The Kessler Syndrome right now is a potentially exponential problem that we should be conscientious of because our access to space depends on open orbital lanes.
I want to submit a YC application proposing an orbital debris mitigation as a service company but im not sure if it's an idea YC will facilitate
The science behind the movie Gravity wasn't too accurate but the scenario the characters found themselves in is very very plausible.
The reason why I don’t think COPVs are a good design for an external pressure application is the load direction; carbon fiber tow doesn’t really do well maintaining an external load. Think back to the watermelon example; apply an increased external pressure and the rubber bands really don’t help with withstanding that increased pressure.
Carbon fiber itself is very difficult to verify that you have the correct properties once they're wound onto the tank. The properties are anisotropic meaning depending on the direction of the fiber you’re gonna get different mechanical properties. Defects like delamination (when a wind unwraps) or voids between the tank wall and fiber are common if you don’t have a qualified winding operation and really really good procedures. In short, while not needing software, repeatability in manufacturing a COPV is incredibly difficult. Part of the reason SpaceX switched to metal tanks is that the mechanical properties of stainless actually increase in a cryogenic environment so there’s an added benefit.
In 2016, SpaceX’s Falcon 9 carrying AMOS-6 exploded during a routine static fire due to a buckled liner of a COPV on the 2nd stage LOX tank. The liner buckled which created a void between the liner and the fiber overwrap which then developed solid oxygen (or an ingress of LOX) that initiated an explosion due to friction. Falcon 9 had been flying for 6 years at that point so I’d consider that a pretty mature or at least an “operational” vehicle so for it to explode on the pad like that is how tricky COPVs can be.
EDIT: Spelling and clarification on delamination