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Post by theholyinquisition on Apr 14, 2017 3:58:21 GMT
Actually, if I may quote from Ignition! An Informal History of Liquid Rocket Propellants: "G. M. Beighley, at Aerojet, tried another approach, this one resembling the usual bi-propellant arrangement. His two propellants were liquid hydrogen and a slurry of powdered beryllium metal in liquid oxygen. He was able to report his results by 1966, and they were not encouraging. He never got more than 70 percent combustion efficiency, and was plagued by "burnbacks" of his Be-O2 slurry through the injector. It's really surprising that he didn't manage to kill himself.
At any rate, he didn't continue the work, and as little has been heard of the Be-H-O system in the last few years, it is probably dead. When the combustion difficulties are added to the toxicity of BeO and the price of beryllium, there isn't really much point in continuing with it. "
So, yeah, when the man who worked in propellant chemistry from 1948 until the 1960s says it won't work, it probably won't work.Well, what if we changed that setup so that the beryllium powder was in the Hydrogen instead of in the Oxygen? Sure, you wouldn't be able to use regenerative cooling unless you were using a material that didn't oxidize for a nozzle without risk of either the nozzle oxidizing through or having a buildup of beryllium deposits in the channels, but you wouldn't have that burnback issue, because there isn't any oxygen in the H2/Be slurry, and the O2 doesn't have any fuel in it. And non-regeneratively cooled engines are already a thing IRL (see also, RL-10B2, IIRC). Alternatively, you could have it so that the Be-H2 slurry isn't pre-mixed in the tank, but the Be powder is instead added on the way to the engine, and some of the hydrogen is routed around the powder adding system and instead used to regeneratively cool the engine. Well, the first reason is that not pre-mixing makes your engine even more complex, which is not something you want. Second, that 70% combustion efficiency means that the beryllium isn't burning at all, which is understandable because it only burns at 1000 degrees celsius. |
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Post by newageofpower on Apr 14, 2017 5:10:24 GMT
Pre-mixing fuel and oxidizer increases combustion efficacy at the cost of additional complexity (and danger of KABOOM); something that is basically implied in our highly efficient CoADE rocket designs.
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blkcandy
Junior Member
Burn complete. Crawling back to bed.
Posts: 78 
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Post by blkcandy on Apr 14, 2017 6:19:47 GMT
All of our designs were min-maxed. Many were less than 0.01% away from total catastrophe.
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Post by Zerraspace on Apr 14, 2017 9:53:02 GMT
Yeah, if these were for real ships I’d be working with a safety factor (1.2 to 1.5 probably, got to consider mass is an issue here), plus a bit more structural mass to keep things held together. 3 mm of aluminium might be good for the space shuttle external tank, but I’d like something a little more substantial for a combat craft, and most of my ships have plenty of acceleration and delta-v to spare. Returning to designs, based on RiftandRend's earlier feedback and simply a desire to further explore the editor, I decided to go ahead and make my own drones. This time around I had quite a bit less to go on, and this is what I deduced are good requirements based on my own intuition and what I’ve seen in the channels: -Since a drone is probably countering shots, missiles and other drones, it needs to have good range for small cross-sections -Since a drone is going to stay out for long durations and is meant to be reusable, it needs much better armor than missiles -Since a drone is going to be out for a lot longer to get shot at, it needs to have a small cross-section -Since a drone doesn’t have to rush anywhere, acceleration is not as important as in missiles -Since a drone is expected to stay out for extended periods, it requires a significant burn time -Since a drone is (usually) a combat platform, all weapons should be turreted and have good turn time to assist aiming So I went into the process with certain baseline expectations for delta-v, acceleration and mass – 7.5 km/s, 10 g’s, 15-30 tons – till I had trouble applying it for one of the drones, seeing as it carried a particularly heavy weapon that was meant for my capital ships. It’s while tweaking this that I realized that raising the delta-v to fill the quota was adding a lot of extra mass and taking away much of the maneuverability. Moreover, the former missile engines, while giving great thrust, had very small gimbals to maintain their narrow profiles which meant long turning times for the drones. Hence, I went back and revised all of the drones, setting new limits – 6 km/s, 6 g’s, 15-25 tons, 1 minute burn time, 1.2 seconds turning time or less – which I was able to achieve. And here they are, after much tweaking with tanks to achieve the desired profiles, and making new custom engines and weapons: Gun Drones  The Pepperspray uses the stock 200 kW coilgun modified to be turreted, simply because it’s so light and low power that I could mount a ton of them all around to ensure firepower can be amassed in any direction. I did my best to array the guns around the center of mass to control recoil. The Gunspray is meant as a replacement for the Hellfire drone and was going to have a fourth 30 mm cannon when I figured I saved quite a bit of mass and cross-section without it. I’m not particularly pleased with this one – the large ammo cartridges required a deep gap to fit and the guns aren't much better than stock (the 30 mm is turreted for half the mass and the 60 mm launches 50 gram shells instead of 10 like the stock) – but it is my first attempt at using conventional weaponry. Laser Drones  There isn’t much to say about these two, save that the turrets are probably larger and heavier than you would be comfortable with due to my obsession with range and good armor. The light version uses a 1 MW laser, the medium-light uses a 15 MW version and was quite a hassle to get to this length due to the number of radiators required. The light laser drone still maintains most of the more stringent original requirements, since I didn’t think it would be worth it to develop yet another smaller engine just for this drone. Multiplatform Drones  The Firespray drone is nothing more than an upsized Pepperspray drone featuring a small missile dispenser. It’s currently configured to carry fifty 25 kilogram 5 kg flak explosive Smallbombers – my first and thus far only attempt at a mini-missile – but it wouldn’t be any hassle to convert it to carrying my new version of the Nuclear Gyrojet. I went back and changed that to run on CH4/O2, which boosted its delta-v past 2 km/s as I’d hoped. The Multilaser drone was envisioned as a mixed fighting and point defense drone, with a major turret for hitting at range and a vast number of smaller turrets for taking out several projectiles or small missiles, though I realize the lasers’ tendency to fire on the same missile would probably render this ineffective. This was aggravated by the requirement for two different types of lasers to handle the different sized mounts – I really wish you could use the same device for both, and frankly, should probably have sufficed with small turrets. That being said, I’m particularly pleased with this drone, not because of its current capabilities but because of how much I was able to improve it. The original weighed 35 tons and had five sets of radiators; this one is under 25 tons and much shorter. Not displayed is my attempt at a far better equipped multilaser drone with several mixed 1 and 15 MW far range turrets. Said drone would probably be devastating but ended up being an overly massive beast – 300 tons – that I decided it was really too much to pack on most ships, and would probably better serve as a small capital ship. The Virgil could probably handle it though. Sniper Drone  I only made one of these, so I compared it to the closest stock variant available, the Lancer drone. Funnily enough, they use the same weapon, after a fashion - the 5 mm railgun is a modified form of the 200 kW 4 mm railgun since it was light, fast, far hitting and efficient. I modified it for use on my own capital ships (it's what the Virgil and Catch Me If You Can packed) but lighter, higher power and turreted, then subsequently remodified it for the drones because some of my own changes cut out most of its close range. This reintroduced a bit of its old mass (it's now 2.6 tons instead of 2 tons), but hitting 1 m2 at 12 km instead of 2 km is worth it. Doing it with 100 rounds per second is even better. |
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Post by ash19256 on Apr 15, 2017 1:40:57 GMT
Well, what if we changed that setup so that the beryllium powder was in the Hydrogen instead of in the Oxygen? Sure, you wouldn't be able to use regenerative cooling unless you were using a material that didn't oxidize for a nozzle without risk of either the nozzle oxidizing through or having a buildup of beryllium deposits in the channels, but you wouldn't have that burnback issue, because there isn't any oxygen in the H2/Be slurry, and the O2 doesn't have any fuel in it. And non-regeneratively cooled engines are already a thing IRL (see also, RL-10B2, IIRC). Alternatively, you could have it so that the Be-H2 slurry isn't pre-mixed in the tank, but the Be powder is instead added on the way to the engine, and some of the hydrogen is routed around the powder adding system and instead used to regeneratively cool the engine. Well, the first reason is that not pre-mixing makes your engine even more complex, which is not something you want. Second, that 70% combustion efficiency means that the beryllium isn't burning at all, which is understandable because it only burns at 1000 degrees celsius. Well, if not pre-mixing the H2-Be would make the system too complex, what about burning a H 2-Be slurry and LOX? Granted, IRL, you wouldn't be able to do regenerative cooling with this particular engine, but I don't see any reason why you couldn't design an engine that is either radiatively or ablatively cooled for the purpose of burning that fuel? Besides, that would definitely get rid of the burnback issue. |
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Post by theholyinquisition on Apr 15, 2017 2:40:32 GMT
Well, the first reason is that not pre-mixing makes your engine even more complex, which is not something you want. Second, that 70% combustion efficiency means that the beryllium isn't burning at all, which is understandable because it only burns at 1000 degrees celsius. Well, if not pre-mixing the H2-Be would make the system too complex, what about burning a H 2-Be slurry and LOX? Granted, IRL, you wouldn't be able to do regenerative cooling with this particular engine, but I don't see any reason why you couldn't design an engine that is either radiatively or ablatively cooled for the purpose of burning that fuel? Besides, that would definitely get rid of the burnback issue. That's a good idea, but: the engine still doesn't burn the beryllium. |
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Post by ash19256 on Apr 15, 2017 2:57:31 GMT
Well, if not pre-mixing the H2-Be would make the system too complex, what about burning a H 2-Be slurry and LOX? Granted, IRL, you wouldn't be able to do regenerative cooling with this particular engine, but I don't see any reason why you couldn't design an engine that is either radiatively or ablatively cooled for the purpose of burning that fuel? Besides, that would definitely get rid of the burnback issue. That's a good idea, but: the engine still doesn't burn the beryllium. I don't see why a LH2/LOX engine (at least in CoaDE) wouldn't burn the beryllium. We easily hit more than 1000 K in the even the nozzle of the engine, so I don't see why the beryllium wouldn't burn when it hit the LOX stream. |
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Post by theholyinquisition on Apr 15, 2017 22:23:03 GMT
That's a good idea, but: the engine still doesn't burn the beryllium. I don't see why a LH2/LOX engine (at least in CoaDE) wouldn't burn the beryllium. We easily hit more than 1000 K in the even the nozzle of the engine, so I don't see why the beryllium wouldn't burn when it hit the LOX stream. Because it didn't work in real life. |
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Post by newageofpower on Apr 16, 2017 0:41:47 GMT
I don't see why a LH2/LOX engine (at least in CoaDE) wouldn't burn the beryllium. We easily hit more than 1000 K in the even the nozzle of the engine, so I don't see why the beryllium wouldn't burn when it hit the LOX stream. Because it didn't work in real life. The IRL design had filthy heresies such as SAFETY MECHANISMS and MARGINS FOR ERROR. We, the GLORIOUS MINMAXER COADE ENGINEERS shall avoid such follies and approach THEORETICAL MAXIMAL LIMITS. IN NOMINE Sempai~. |
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Post by ross128 on Apr 16, 2017 3:28:38 GMT
If we truly wish to have no regard for safety or chemical reactivity, then either FOOF or chlorine trifluoride would be the oxidizer of the future.
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Post by theholyinquisition on Apr 16, 2017 4:39:39 GMT
If we truly wish to have no regard for safety or chemical reactivity, then either FOOF or chlorine trifluoride would be the oxidizer of the future. Actually, if we can get tripropellants working, a tank of mercury pumped into your combustion chamber should boost thrust nicely. |
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Post by theholyinquisition on Apr 16, 2017 4:52:31 GMT
Because it didn't work in real life. The IRL design had filthy heresies such as SAFETY MECHANISMS and MARGINS FOR ERROR. We, the GLORIOUS MINMAXER COADE ENGINEERS shall avoid such follies and approach THEORETICAL MAXIMAL LIMITS. IN NOMINE Sempai~. As much as I appreciate the memeing: Everything in the game has been tested and tried in real life. Even the Fluorine/lithium/hydrogen was designed, built, and fired at test stand. (warning, large pdf.) |
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Post by RiftandRend on Apr 16, 2017 7:03:58 GMT
If we truly wish to have no regard for safety or chemical reactivity, then either FOOF or chlorine trifluoride would be the oxidizer of the future. Actually, if we can get tripropellants working, a tank of mercury pumped into your combustion chamber should boost thrust nicely. Wouldn't the temperature losses due to the added mercury reduce the thrust more rapidly than the added exhaust mass? |
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Post by newageofpower on Apr 16, 2017 7:49:40 GMT
Actually, if we can get tripropellants working, a tank of mercury pumped into your combustion chamber should boost thrust nicely. Wouldn't the temperature losses due to the added mercury reduce the thrust more rapidly than the added exhaust mass? Yep. I don't think it's a good idea; the thrust/efficiency (i.e. dV) trade-off is too massive. Also, Mercury has very different vaporization and fluid flow characteristics from, say, methane propellant. Injecting Mercury into the fuel stream may cause explosive disassembly events. |
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Post by The Astronomer on Apr 16, 2017 8:03:55 GMT
Wouldn't the temperature losses due to the added mercury reduce the thrust more rapidly than the added exhaust mass? Yep. I don't think it's a good idea; the thrust/efficiency (i.e. dV) trade-off is too massive. Also, Mercury has very different vaporization and fluid flow characteristics from, say, methane propellant. Injecting Mercury into the fuel stream may cause explosive disassembly events. Inject in small amount to cause small explosions, which enhance exhaust velocity and thrust? |
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