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OT - What can you do with this Motor?

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  • Swarf&Sparks
    replied
    OK Evan, catch your drift.

    BTW, I still have several resolvers from that Russian radar.
    I'd be happy to send you a couple or 3 to play with if you have a use for them.

    Only one I've used so far, I took out the rotor and stator and used the SS housing for an outdoor surveillance camera

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  • Evan
    replied
    By resolver I presume you mean the remote indicators used on devices such as a wind cock so the reading can be seen on a dial elsewhere.

    The answer is that it somewhat of similar. The drive amplfiers are looking for a consistent rev to rev signal that they produce. It doesn't really directly read the rotor position. The back EMF changes the pulse shape that the amplifier produces and by sensing that via a sense resistor and integrating that over a portion of each rev the phase information is derived and the timing changed accordingly.

    What looks like a single disk or ring magnet in that sort of motor is really the equivalent of a series of independent magnets. They are magnetized in a multipole pattern. You can determine that by passing a small magnet over the disk. Or, you can sprinkle some cast iron swarf on the motor magnet if you don't mind contaminating it.

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  • Swarf&Sparks
    replied
    So is that anything like a resolver?

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  • Evan
    replied
    It has 9 windings, no visible feed back mechanism and a permanent magnet in the spindle/hub.
    It's done by sensing back emf. The magnets generate a signal in the drive coils as they turn and that is sensed to provide phase information.

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  • Swarf&Sparks
    replied
    Now ya gone and dun it Evan!

    An all them oil companies know where you live

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  • Evan
    replied
    I don't recall for sure. I seem to remember they were run from the intake side. There are descriptions online somewhere. Considering the materials we have now they could probably build one with ten times the efficiency and probably unmeasurable contamination. Imagine how that would affect the long distance travel business.

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  • Swarf&Sparks
    replied
    HEPA??!, hell we used to call em a cyclone.

    BTW Evan, how did they run the control rods in them there nuclear jets?

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  • clutch
    replied
    So this motor is basically a stepper with an electronic control to 'step' it at whatever speed needed?

    At first I thought it was one of those that uses hal effect sensors to simulate a commutator.

    I have a direct drive CD player spindle motor in pieces right now, I wonder if that is an example of the motor type referred to in the original post? It has 9 windings, no visible feed back mechanism and a permanent magnet in the spindle/hub.


    Clutch

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  • Evan
    replied
    How's it going Tryp? I don't know if you caught the thread but I now have an original Whipp shaper vise for the shaper you gave me. Dennis (DP) gave it to me in exchange for some jewellery I made. Long story, in the archives.


    Have you had a chance to visit Standard Modern yet?

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  • tryp
    replied
    Didn't a German? company recently anounce a 1 million rpm motor that would be the bleeding edge of technology. This would be nothing but a marketing hook, as stated above. psssht!

    This dyson guy is a marketing specialist, and he has managed to turn a vacuum cleaner into the next high tech must have gadget for guys. The dyson vacuum isn't revolutionary for technology its the styling that sells and has 24 year old guys bragging to each other about their new vacuum cleaner.

    What would a vacuum cleaner need a 100k rpm motor for anyways? I would think that a good cleaner motor should have lots of volume, good efficiency when restricted and have such a service factor rating that it would never overheat when subjected to ignorant users of consumer equipment that will stall it out or run it restricted.

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  • Evan
    replied
    BTW, the plans for a nuclear ramjet are on the shelf sitting there. The engine design is fully ground qualified for flight test. It was built and tested in Nevada back in the 60s but was canceled for political reasons. It required no fuel other than the uranium fuel rods as it relies on simply heating the air as it passes through the reactor. The design is dead simple and generates only trace amounts of free isotopes in the exhaust due to slight erosion of the ceramic core cladding as it operates. An aircraft so powered could in theory stay aloft for months.

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  • Evan
    replied
    You don't need supersonic inlet conditions to get shock diamonds in the exhaust
    No, you don't, but you only see them in a supersonic exhaust plume. Most jet turbine exhausts are subsonic and even if they start out supersonic they immediately drop to subsonic. Shock diamonds are a string of solitons in the gas flow with a soliton being a self reinforcing solitary wave pattern. It takes a very high velocity exhaust to produce them.

    I have heard many a sonic boom from when I was a child. We lived directly under the test flight path of the XB70. It made a very distinctive double boom. It is also possible for a sonic boom to be generated by an aircraft treling below mach 1. If the conditions are just right or the aircraft hits some clear air turbulence portions of the airframe can generate shock waves momentarily.

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  • interrupted_cut
    replied
    You don't need supersonic inlet conditions to get shock diamonds in the exhaust. I've seen seen them multiple times in low level afterburner passes by F-15's, F-16's and F-18's at airshows. The only times I've ever seen supersonic passes at airshows were at Edwards for the 50th anniversary of Yeager's flight where they did it on purpose, and once at Point Mugu, where an incoming cold front shifted the local mach number below the speed of an F-14 who was supposed to perform a low level fly-by at .95 mach. Or at least that's how they explained it away afterwards while everyones ears were still ringing and all the car alarms were going off.
    Jet engine designers may hate gears, but they must hate turbine blades and stators more. GE and Pratt & Whitney are both developing Geared Turbo Fans for the next generation of transport engines. Pratt engineers say that they will save ~1400 pieces (!) from the hot section assembly by driving the fan off of the high pressure turbine. Those hot section parts are where most of the manufacturing and maintenance costs are.

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  • Evan
    replied
    No, with one major exception. A "pure" ramjet has no moving parts except the engine itself. It relies on the supersonic shock wave at the inlet to both slow down and compress the air to subsonic velocity within the engine where compression heating provides sufficient temperature for ignition as fuel is sprayed in. The combustion gasses expand out the back and thrust is produced.


    The exception is the J58 turbo-ramjet used in the SR71. It is a hybrid engine and switches to ramjet mode at supersonic speeds. It's easy to tell there is something different about it when you look at the exhaust.



    Those are called thrust diamonds and you only see them in a supersonic exhaust plume. The test stand for the engine supplies it with supersonic intake air. That is done by pumping up a "tank farm" of air receivers to high pressure and then blowing them down all at once to feed the engine intake.
    Last edited by Evan; 07-01-2009, 05:25 PM.

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  • mayfieldtm
    replied
    So Evan... Would a Pure Jet be similar to a Ram Jet?

    Tom M.

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