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Model Forum / General / Rockets / July 2004turbopumps for model rockets
Does anyone do turbopumps for model rockets powered by Lox/whatever, especially Lox/LH2? I can probably build everything except the turbopumps, which kind of implies that a lox/whatever pressure-fed model is not totally out of the question. But I'd like to do turbopumps as well ... I expect they will probably have size/performance limitations, like model-size jets - except model-size jets aren't _that_ limited in things like thrust-to-weight ..  SignaturePeter Fairbrother Turbopumps are unobtanium even in full scale applications. Just ask Mr Musk at Space X or anyone in the motor Mafia. They are one of the most expensive, temperamental, highest risk components in any propulsion system and are application specific. The technical challenges are at least an order of magnitude greater than the miniaturization of a gas turbine. They also don't trade well against alternatives such as positive displacement schemes in systems under 2.5K pounds of thrust. There has been some work in this area but the pump dynamics are far from trivial. An example can be found at http://www.m-dot.com/ . Anthony J. Cesaroni President/CEO Cesaroni Technology/Cesaroni Aerospace http://www.cesaronitech.com/ (905) 887-2370 x222 Toronto (410) 571-8292 Annapolis > Does anyone do turbopumps for model rockets powered by Lox/whatever, > especially Lox/LH2? [quoted text clipped - 6 lines] > model-size jets - except model-size jets aren't _that_ limited in things > like thrust-to-weight .. > Turbopumps are unobtanium even in full scale applications. Just ask Mr Musk > at Space X or anyone in the motor Mafia. They are one of the most expensive, [quoted text clipped - 5 lines] > but the pump dynamics are far from trivial. An example can be found at > http://www.m-dot.com/ . I've seen the M-dot site: their stuff looks beautiful - and most likely expensive! Your comment about positive displacement systems is interesting... on a small-scale, I wonder how well something like a miniature piston engine driving something a lobed-rotor pump would work. (Imagine the oil pump from a motorcycle engine as the feed pump, with a good size model racing boat glow engine spinning it... darn! now I'll have to run some numbers for a reality check!) -dave w > > Turbopumps are unobtanium even in full scale applications. Just ask Mr Musk > > at Space X or anyone in the motor Mafia. They are one of the most expensive, [quoted text clipped - 17 lines] > > -dave w But a turbopump only has 4,000+ parts and is the highest performance to mass mechanical device on the planet. What's the problem? :) SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring common sense back to rocketry administration. Produce then publish. http://www.usrockets.com My articles valuable? Donate http://tinyurl.com/2hmgv >> Turbopumps are unobtanium even in full scale applications. Just ask Mr Musk >> at Space X or anyone in the motor Mafia. They are one of the most expensive, [quoted text clipped - 8 lines] >I've seen the M-dot site: their stuff looks >beautiful - and most likely expensive! OTHO, it looks like their stuff is geared toward mass produced expendable vehicles. >Your comment about positive displacement systems is interesting... >on a small-scale, I wonder how well something like a miniature [quoted text clipped - 4 lines] > >-dave w I'm not a motor head, but dragster motors put out some impressive HP at low mass, for suitably brief periods of time. I understand that there has been some development of hydrogen fueled internal combustion engines as well. Although, I can't imagine sport rocketeers ever working with liquid hydrogen. As a practical matter (!?), I'd expect the next major development in sport rocketry to be pressure fed LOX hybrid motors. This would ease ignition while raising Isp, at the expense of working with LOX and high pressure nitrogen. Alan > I'm not a motor head, but dragster motors put out some impressive HP > at low mass, for suitably brief periods of time ~5900BHP @ ~7200RPM . Torque in the 6000 lb.-ft. range, too. After about 35secs (start, burn out, back up and pass) a nitromethane motor will vaporize pistons, rings and sparkplugs. Other anomalies associated can be clutch pack overheating and motor "hydraulicking" (breakdown of the ignition cycle - sometimes by a melted or otherwise disintegrated spark plug or other failed ancillary ignition periphery - fills a cylinder with unburned, semi-unvaporized nitro. When the volume reaches a critical mass, it detonates and obliterates the cylinder head/cylinder wall/engine block enmasse during a compression stroke. Often takes out the supercharger, too. Think a CATO's a bad day? :-)> ) I have yet to see any convincing engineering data to substantiate the horsepower claims of top fuel dragsters. No one in recent times has run one of those motors on a dynamometer that I'm aware of so the published data you read or see on Speed Vision is speculated hype and bench racing IMHO. Most of the fuel that passes through those engines is used to cool them and they operate far from stoichiometric A/F ratios. Note the ten foot flames from the headers. There are plenty of dynos that can handle the acceleration rates and power of those motors available if they required. We have two dynamometer test cells and have a group here that builds dynamometer systems on a commercial basis so I have a bit of incite on the topic. I suspect that drag racing budgets are too restrictive to do this type of R&D anyway. A Formula 1 engine is far more sophisticated and efficient but then they have the technology and the budgets. Neither however compare to the power density of a turbopump and a top fuel dragster engine falls well behind in all respects. The HPTFP on the SSME is 58,978 horspower and a lot smaller and lighter than a T/F engine. It's also 78% efficient. Anthony J. Cesaroni President/CEO Cesaroni Technology/Cesaroni Aerospace http://www.cesaronitech.com/ (905) 887-2370 x222 Toronto (410) 571-8292 Annapolis > > I'm not a motor head, but dragster motors put out some impressive HP > > at low mass, for suitably brief periods of time [quoted text clipped - 9 lines] > enmasse during a compression stroke. Often takes out the supercharger, too. > Think a CATO's a bad day? :-)> ) Ken Veney's dyno. I rarely believe what I hear or read. Unless I see it. > Neither however compare to the power density >of a turbopump and a top fuel dragster engine falls well behind in all >respects. The HPTFP on the SSME is 58,978 horspower and a lot smaller and >lighter than a T/F engine. It's also 78% efficient. Sure, but can you pick up a used SSME at the junk yard for $1000 or so? How much HP would a max size HPR pump fed LOX hybrid actualy need? Actualy I was hoping that you would comment on the pressure fed LOX vs, nitrous oxide trades. At what motor size does the LOX start looking more practical? Alan >Anthony J. Cesaroni >President/CEO >Cesaroni Technology/Cesaroni Aerospace >http://www.cesaronitech.com/ >(905) 887-2370 x222 Toronto >(410) 571-8292 Annapolis > Actualy I was hoping that you would comment on the pressure fed LOX > vs, nitrous oxide trades. At what motor size does the LOX start > looking more practical? We did a 29mm LOX/CPVC hybrid (Rattworks like hardware) and despite the load/ignite being a bit hectic it had superlative ISP. Jerry SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring common sense back to rocketry administration. Produce then publish. http://www.usrockets.com My articles valuable? Donate http://tinyurl.com/2hmgv >>Actualy I was hoping that you would comment on the pressure fed LOX >>vs, nitrous oxide trades. At what motor size does the LOX start [quoted text clipped - 4 lines] > > Jerry Who is "we"? >> We did a 29mm LOX/CPVC hybrid (Rattworks like hardware) and despite the >> load/ignite being a bit hectic it had superlative ISP. >> >> Jerry > >Who is "we"? My guess would be the Pacific Rocket Society. Jerry is a member, and I've seen a number of photos of interesting motor designs, including LOX hybrids, that PRS has tested. - Rick "Some things he says *can* be taken at face value" Dickinson Signature"Oh, I'm more than happy to deliberately make myself look like a clueless idiot for the sake of argument. Any argument, I might add." -- Arvid Grøtting >>> We did a 29mm LOX/CPVC hybrid (Rattworks like hardware) and despite the >>> load/ignite being a bit hectic it had superlative ISP. [quoted text clipped - 6 lines] > I've seen a number of photos of interesting motor designs, including > LOX hybrids, that PRS has tested. Aspirespace have also tested Lox/CPVC hybrids http://www.aspirespace.org.uk/ SignaturePeter Fairbrother > >>> We did a 29mm LOX/CPVC hybrid (Rattworks like hardware) and despite the > >>> load/ignite being a bit hectic it had superlative ISP. [quoted text clipped - 9 lines] > Aspirespace have also tested Lox/CPVC hybrids > http://www.aspirespace.org.uk/ Here is a movie of loading a larger LOX-HTPB pressure fed hybrid that was quite successful. http://www.v-serv.com/prs/7-10-04/IM001516.AVI It is 3.6 MB and it is sideways in the frame. SignatureJerry Irvine, Box 1242, Claremont, California 91711 USA Opinion, the whole thing. <mail to:01rocket@gte.net> Please bring common sense back to rocketry administration. Produce then publish. http://www.usrockets.com My articles valuable? Donate http://tinyurl.com/2hmgv > > Actualy I was hoping that you would comment on the pressure fed LOX > > vs, nitrous oxide trades. At what motor size does the LOX start > > looking more practical? > > We did a 29mm LOX/CPVC hybrid (Rattworks like hardware) and despite the > load/ignite being a bit hectic LOL! I can imagine! > it had superlative ISP. -dave w > Turbopumps are unobtanium even in full scale applications. Just ask Mr Musk > at Space X or anyone in the motor Mafia. They are one of the most expensive, [quoted text clipped - 3 lines] > trade well against alternatives such as positive displacement schemes in > systems under 2.5K pounds of thrust. Thanks for the reply. Could you clarify what you mean by "positive displacement schemes"? Do you mean using PD pumps? > There has been some work in this area > but the pump dynamics are far from trivial. Could you give some references, especially to the pump dynamics problems? I'm not sure what you are referring to, although I do know of some scaling problems. The power turbine should be fairly easy, although the preburner or gas generator is a problem still to be solved, and using hollow screw Quimby type PD pumps has always seemed a good possibility to me, although the gearing might be a weight problem. I've done some BOTE calculations, and I think I could build a 300-500 lb thrust Lox/kero turbopumpedrocketengine (there has got to be a better word) with a chamber pressure of ~ 600 psia, and stay under 6.5 lbs weight, and perhaps even under 5 lbs. Will cost a lot of $1,000s each tho'. Something around 150-200 pounds thrust at around 3 lb weight might also be possible. Unfortunately the price would be pretty much the same. The turbopumps will probably not be very efficient, but for a staged combustion cycle that would not matter (or for an expander cycle we'll recover sufficient power from the cooling anyway ...) SignaturePeter Fairbrother LEO - miss, mile, ... > Does anyone do turbopumps for model rockets powered by Lox/whatever, I've never needed one for my Lox. Just a bagel and come cream cheese. I should eat it more often, since the fat is the good stuff that I take in pill form anyway. Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle: http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org Save Model Rocketry from the HSA! http://www.space-rockets.com/congress.html |
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