turbopumps for model rockets

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

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Anthony J. Cesaroni President/CEO Cesaroni Technology/Cesaroni Aerospace

887-2370 x222 Toronto (410) 571-8292 Annapolis

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

But a turbopump only has 4,000+ parts and is the highest performance to mass mechanical device on the planet. What's the problem?

:)

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!

OTHO, it looks like their stuff is geared toward mass produced expendable vehicles.

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

~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

887-2370 x222 Toronto (410) 571-8292 Annapolis

Ken Veney's dyno.

I rarely believe what I hear or read. Unless I see it.

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

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"?

LOL! I can imagine!

-dave w

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