Quote from: A_M_Swallow on 10/05/2016 12:51 amThe main engine of a spacecraft may be a large engine but its RCS can be medium sized. Using the same propellant can simplify the design of the vehicle.Start up are short of money and have a small time to market. An off the shelf engine reduces both.You typically don't see staged combustion thrusters for RCS. There is a reason for this-they take too long to startup and shutdown. In order to get RCS-type speeds you can't really have turbomachinery. Imagine if your steering wheel took 1 second to turn on and then another to turn off when you were driving. You would crash.The same applies for escape motors. Hence why superdraco is pressure-fed. Also, pressure-fed hypergolic is about the easiest possible engine to develop.
The main engine of a spacecraft may be a large engine but its RCS can be medium sized. Using the same propellant can simplify the design of the vehicle.Start up are short of money and have a small time to market. An off the shelf engine reduces both.
Seems they did some tests with their engine. Look like the pump assembly is mounted directly on top of the thrust chamber. Fuel rich turbine exhaust goes straight to the thrust assembly looks like.https://www.instagram.com/p/BQgeqdfh000/?taken-by=ursamajortechnologies
vonbraunnabe: Is this a hot fire of the full engine?! Or just the preburner?ursamajortechnologies: Full engine
More firehttps://www.instagram.com/p/BSUTaznh7Y2/Moar color:Quotevonbraunnabe: Is this a hot fire of the full engine?! Or just the preburner?ursamajortechnologies: Full engine
Quote from: savuporo on 04/03/2017 02:43 amMore firehttps://www.instagram.com/p/BSUTaznh7Y2/Moar color:Quotevonbraunnabe: Is this a hot fire of the full engine?! Or just the preburner?ursamajortechnologies: Full engineIs it just me or is that an unhealthy shape for a rocket expansion?
And looks like a proper hot fire:https://www.instagram.com/p/BUK8tdql7TK/?taken-by=ursamajortechnologies
Great to see them progressing. The choice of ORSC is interesting, at low turbine inlet temperatures can still get good chamber pressures (1000+ psi) compared to gas generators, but with a penalty of increased weight and complexity. This also leaves a large margin for improvements down the line. Mounting the turbopumps directly on the MCC and 3D printing should help the weight.Not sure what application this is aimed at. The 5klb engine seems like a learner engine, though it could make an interesting in space motor, particularly if its capable of restarts. 35klb at the small sat launcher market, but for a booster stage does the extra weight compared to a gas generator make sense?
Test fire video of our Hadley engine. America's first Oxidizer Rich Staged Combustion (ORSC) rocket engine. Fully designed and built in #Colorado #USA. Turbopump included.
We got some flamey videohttps://www.instagram.com/p/BWYrUQ1lc87/
That was what, 15-20yrs ago now? Has anyone revisited his assessment based on modern manufacturing, materials, and CAE capabilities?
2- They're then planning to do a ~35klbf LOX/Kero or LOX/Methane engine, also leveraging 3D printing and staged combustion.Ursa's pretty clear that their 35klbf LOX/HC concept is focused on addressing what they think the microsat launch market is looking for in a first stage booster engine, not trying to compete with XCOR/AJR/Blue for the ACES upper stage engine contract. And ULA is not going to switch from LOX/LH2 for ACES. Full-stop. But, that doesn't mean Ursa couldn't subsequently adapt this to LOX/LH2 and add a nozzle extension for upper-stage operations. The Ursa team does have the LOX/LH2 experience to do so from their BE-3 days, but it would depend on them identifying a clear and believable market opportunity. That's just not something that I think is on their radar currently.
Quote from: jongoff on 10/15/2016 03:27 pmThat was what, 15-20yrs ago now? Has anyone revisited his assessment based on modern manufacturing, materials, and CAE capabilities?i think the issues are that below that size turbines have very tight tolerance. Some phenomena scale down very badly. A blade that was 100x the boundary is suddenly 5x the boundary layer thickness. Surface finishes have to be much better, seal clearances. Basically the combustion chemistry and flow properties have not changed. What has changed is the wider availability of small size, high accuracy CNC to make such components. My instinct is this is not an area where 3D printing scores, as it needs a lot of post processing to get the surface finish and grain quality, as smaller parts are going to spin a lot faster. This is (potentially) offset by a better ability to make the blades lighter (more like a honecomb) Personally I'd like to see someone go with an engine made using photo etched foils diffusion bonded together. Aerojet make a big play of this for combustion chambers and injectors, but I think it could be taken a lot further. A few ideas occurred to me that I've not seen implemented Quote from: jongoff2- They're then planning to do a ~35klbf LOX/Kero or LOX/Methane engine, also leveraging 3D printing and staged combustion.Ursa's pretty clear that their 35klbf LOX/HC concept is focused on addressing what they think the microsat launch market is looking for in a first stage booster engine, not trying to compete with XCOR/AJR/Blue for the ACES upper stage engine contract. And ULA is not going to switch from LOX/LH2 for ACES. Full-stop. But, that doesn't mean Ursa couldn't subsequently adapt this to LOX/LH2 and add a nozzle extension for upper-stage operations. The Ursa team does have the LOX/LH2 experience to do so from their BE-3 days, but it would depend on them identifying a clear and believable market opportunity. That's just not something that I think is on their radar currently.Fair point. 35Klb does sound like a nice granular size for a first stage microsat booster engine. One think I note though is that any SC engine that does not have 2 turbines, one Ox rich, one fuel rich will always have a critical seal between the between the preburner and one or the other propellant pumps. Only a twin, ox and fuel rich SC engine can eliminate that failure mode, and the necessary sealing and purge complexity to eliminate the risk of it happening. It seemed odd to me that if you're going to go the SC route why wouldn't you go all in? Get the good T/W and Isp of the SC cycle and simplify the engine design.
Diffusion bonded small scale turbomachinery? You mean like this:
SLA resin 3D printing + investment casting could produce smooth surface.And the problem of surface friction drag scaling happens mainly in cold end pump parts (which have relatively low strength requirements), not in hot end turbine parts.