Design limits of electric motors?

[Clifford Heath]

The gears are just too tempting a tagret for sabatoge.

sabotage - the word has an interesting etymology.

A "sabot" is a wooden shoe, so named by the French peasants
who wore them. We know them as clogs, and tend to associate
them more with the Dutch. Anyhow... during the Industrial
Revolution, "saboteurs" became so-called from their practise
of throwing a sabot into the gears of the machinery, thereby
"clogging up the works" and often breaking the gears.

Irrelevant to electronics, but the kind of thing that geeks
and engineers like to know .

Clifford Heath.

 

[Rich Grise]

For a given drive frequency that's true, and it will be more difficult
to drive a multi-pole motor fast. As far as the torque goes your slots
get smaller when you have more poles, so you can't stuff as much copper
in there, so your torque per pole goes down as fast as the number of
poles goes up.

Well, yes - but is it proportional? If so, then the torque would be
constant, within a reasonable experimental error. ;-) Or so it looks
to me.

Thanks,
Rich

 

[John Larkin]

sabotage - the word has an interesting etymology.

A "sabot" is a wooden shoe, so named by the French peasants
who wore them. We know them as clogs, and tend to associate
them more with the Dutch. Anyhow... during the Industrial
Revolution, "saboteurs" became so-called from their practise
of throwing a sabot into the gears of the machinery, thereby
"clogging up the works" and often breaking the gears.

Irrelevant to electronics, but the kind of thing that geeks
and engineers like to know .

Clifford Heath.

Isn't a sabot also the drop-away casing used on those hypervelocity
uranium tank-killer shells?

John

 

[Joel Kolstad]

sabotage - the word has an interesting etymology. ....
Irrelevant to electronics, but the kind of thing that geeks
and engineers like to know .

Yep, but surely most proper geeks and engineers would have learned it from
Star Trek... uh... VI, I think it was?

 

[Alan McClure]

daestrom wrote:


"John Larkin" +ACY-lt;jjlarkin+AEA-highlandSNIPtechTHISnologyPLEASE.com+ACY-gt; wrote in message news:jkaec0tu69q5o3jsj9ijm0edpr4a95dl3u+AEA-4ax.com...



On Tue, 08 Jun 2004 21:03:37 GMT, "daestrom" +ACY-lt;daestrom+AEA-NO+AF8-SPAM+AF8-HEREtwcny.rr.com+ACY-gt; wrote:



Hate to burst your bubble, but they +ACo-do+ACo- make gearing for this kind of power. Typical steamships use reduction gears between the IP/LP turbines (in thousands of RPM) and the main shaft (hundreds of RPM). And smaller gearing between the HP and IP turbines. Bull-gears, the final output



gear



connected to the propeller shaft are large with double helix cut. Often



use



double-reduction with 'quill' shafts between successive gear stages. Saw more than one bull gear get some broken teeth ground out. Didn't replace the teeth, just ground down the sharp edges so they wouldn't wear into the low-speed pinions (some sailors didn't believe the rules about FOD).



On the ships I saw, the access ports to the main gear were sealed with huge padlocks, and only the Chief had the keys. The gears are just too tempting a tagret for sabatoge.



Yep. But when the sailor has a preventative maintenance procedure to go in and take some measurements, if they aren't careful about restraining all the things about their person, some genuine accidents do happen. And if the sailor is too scared of the 'chief' to admit anything, then it gets left inside. Eventually, with the motion of the ship and all, it gets ground up in the gear. Leaving some damaged teeth behind. daestrom

In the US Navy I was in, ships reduction gears where not opened except for very
carefully planned evolutions.+AKA- All tools/parts/rags/etc. were logged in and logged
back out of a "clean" area around any open reduction gear cover. Any time a cover
was open an armed guard was placed on it to prevent any/all possibility of damage
to the gear. Opening up an red. gear was/is a very rare evolution and is usually
watched closely by the Engineer Officer, the M division officer, and possibly the
ships' Captain.
In addition, the lube oil low pressure alarm for the reduction gear energized a
siren that could wake up the dead two area codes away, just to give an indication
serious even the possibility of damage to the gear is considered.
It was easier for two missile techs to do PMs on a Polaris missile than it was to
get permission to open an inspection cover on the boats' reduction gear.
ARM


ARM

 

[SioL]

daestrom wrote:

<Snipped unreadable html crap>

How light yellow on while background or perhaps even
dark brown on black?

SioL

 

[Zak]

They had atomic turbojets in the 50's (no kidding, and very scary if you
ever consider that airplanes do crash sometimes). Fortunately they
never flew them. _Any_ heat source can be used as long as it transfers
heat to the air quick enough, but I'm not sure if it'd work with a
ramjet because of the speed of the air.

Don't go sit next to the engines in such a plane. Unless it is made of
quite thick lead. Hmmm...


Thomas

 

[Alan McClure]

"John Larkin" <jjlarkin+AEA-highlandSNIPtechTHISnologyPLEASE.com> wrote in
message


Yep. But when the sailor has a preventative maintenance procedure to go in
and take some measurements, if they aren't careful about restraining all the
things about their person, some genuine accidents do happen. And if the
sailor is too scared of the 'chief' to admit anything, then it gets left
inside. Eventually, with the motion of the ship and all, it gets ground up
in the gear. Leaving some damaged teeth behind.

daestrom

Second try. Sorry about the HTML, Mozilla and I haven't come to terms
yet.
ARM



In the US Navy I was in, ships reduction gears where not opened except
for very
carefully planned evolutions.+ACs-AKA- All tools/parts/rags/etc. were logged
in and logged
back out of a "clean" area around any open reduction gear cover. Any
time a cover
was open an armed guard was placed on it to prevent any/all possibility
of damage
to the gear. Opening up an red. gear was/is a very rare evolution and is
usually
watched closely by the Engineer Officer, the M division officer, and
possibly the
ships' Captain.
In addition, the lube oil low pressure alarm for the reduction gear
energized a
siren that could wake up the dead two area codes away, just to give an
indication
serious even the possibility of damage to the gear is considered.
It was easier for two missile techs to do PMs on a Polaris missile than
it was to
get permission to open an inspection cover on the boats' reduction gear.
ARM


ARM

 

[K Williams]

Tim Wescott wrote:

They had atomic turbojets in the 50's (no kidding, and very scary
if you
ever consider that airplanes do crash sometimes). Fortunately
they
never flew them. _Any_ heat source can be used as long as it
transfers heat to the air quick enough, but I'm not sure if it'd
work with a ramjet because of the speed of the air.

Project "Pluto" in the late '50s through '64. The engine (a ramjet,
rather than turbo-jet) was intended to power ICBMs and was tested
(statically) for the duration needed (7 minutes, IIRC). ISTR that
it was also carried aboard a test B36, but un-powered, and perhaps
even un-fueled.

http://www.nv.doe.gov/news&pubs/publications/historyreports/news&views/pluto.htm

 

[K Williams]

Isn't a sabot also the drop-away casing used on those
hypervelocity uranium tank-killer shells?

APDS (I think) = Armor-Piercing Discarding-Sabot rounds are
kinetic-energy killers. The penetrator is necessarily a dense
material, usually either depleted uranium or tungsten. Note that
shot-guns may also use sabots for flechetes. I guess one could
think of the patch around a musket ball as a sabot too. ;-)

 

[s falke]

Project "Pluto" in the late '50s through '64. The engine (a ramjet,
rather than turbo-jet) was intended to power ICBMs and was tested
(statically) for the duration needed (7 minutes, IIRC). ISTR that
it was also carried aboard a test B36, but un-powered, and perhaps
even un-fueled.

http://www.nv.doe.gov/news&pubs/publications/historyreports/news&views/pluto.htm


Riveting.

--s falke

 

[Tim Wescott]

Tim Wescott wrote:





Project "Pluto" in the late '50s through '64. The engine (a ramjet,
rather than turbo-jet) was intended to power ICBMs and was tested
(statically) for the duration needed (7 minutes, IIRC). ISTR that
it was also carried aboard a test B36, but un-powered, and perhaps
even un-fueled.

http://www.nv.doe.gov/news&pubs/publications/historyreports/news&views/pluto.htm

Look up the X-6 program. It was to have been a modified B-36 with a
reactor, heat pipes to the engines, and turbojets with heat exchangers
instead of combustors. They actually flew a modified B-36 test bed with
the reactor waaay in the back and a lead and rubber lined crew capsule
waaay in the front. They also tested the engines on the ground (but I
don't think the heat source was atomic).

 

[Terry Given]

that was horrible! shame on you

Legible Cheers,
Terry

 

[Terry Given]

[email protected] (Andrew Gabriel) wrote in message

This isnt too hard to work round though - but of course that does add
complication. Reduced voltage, dummy loading, monitoring the tacho
output, and designing to avoid no-loads can all work.

Regards, NT

ripping the fan off a vacuum cleaner motor so it runs unloaded is fun too -
just stand well clear.

Cheers
Terry

 

[Rich Grise]

Project "Pluto" in the late '50s through '64. The engine (a ramjet,
rather than turbo-jet) was intended to power ICBMs and was tested
(statically) for the duration needed (7 minutes, IIRC). ISTR that
it was also carried aboard a test B36, but un-powered, and perhaps
even un-fueled.

http://www.nv.doe.gov/news&pubs/publications/historyreports/news&views/pluto.htm

Stick one of those on the ass-end of the shuttle, and just fill the
tank with water, which you shove in the front instead of compressed
air.

Doing that math would kinda be nuclear rocket science, wouldn't it?

Just on a whim, I looked up nerva - here's just one hit:
http://www.aemann.pwp.blueyonder.co.uk/spacecraft/nerva/nerva.html

Cheers!
Rich

 

[Doug]

Well, yes - but is it proportional? If so, then the torque would be
constant, within a reasonable experimental error. ;-) Or so it looks
to me.

Thanks,
Rich

It depends on what you want to remain constant. If you are keeping the
horsepower constant, then reducing the rpm by half will cause the torque to
be twice as much. power = angular velocity x torque x (some correction
factor to make all the units work together) using horsepower, foot pounds,
and rpm HP=(rpm)(torque)/5260.

 

[Doug Goncz]

From: DaveC [email protected]

I began wondering if air flight could ever use electric motors
to drive turbines that would provide equivalent thrust of jet turbine engines

Yes, it can!

But only with the use of fuel.

What has been patented already is the MHD generation of power at efficiency
much greater than turbine power extraction efficiency from a high temperature
(enough to melt a turbine), high pressure, high "enthalpy" gas stream, and the
use of that power to drive a conventional compressor turbine at conventional
electric motor efficiencies in the 90s of percent, with the compressed air
gaining energy from the burning of fuel.

The combination of ultracapacitors and electric fan drive has enough power to
sustain flight for seconds. Batteries, not enough power, and electrolytic
capacitors, insignificant flight time (energy).

Sorry, you can barely drive on stored electrical energy, much less fly. To go
man go, you need fuel, whether it's Gatorade or JP4, because the freely
available energy of oxygen in the air is essentially unlimited.

That's why fuel cell vehicles are promising. Good energy per weight fuel, nice
power per weight reactor.

I can put some PC 2500 ultracaps on ebay if you'd like to tinker with this a
bit. Hazmat: contains methyl cyanide, hermetically sealed. On overcharge,
venting may occur with release of methyl cyanide, and cyanosis. Cyanosis can
result in death.

Reserve price: $70 each.


Yours,

Doug Goncz ( ftp://users.aol.com/DGoncz/ )

Read about my physics project at NVCC:
http://groups.google.com/groups?q=dgoncz&scoring=d plus
"bicycle", "fluorescent", "inverter", "flywheel", "ultracapacitor", etc.
in the search box

 

[daestrom]

daestrom wrote:

"John Larkin"

+ACY-lt;jjlarkin+AEA-highlandSNIPtechTHISnologyPLEASE.com+ACY-gt; wrote in

message On Tue, 08 Jun 2004 21:03:37 GMT, "daestrom"
+ACY-lt;daestrom+AEA-NO+AF8-SPAM+AF8-HEREtwcny.rr.com+ACY-gt; wrote:


Hate to burst your bubble, but they +ACo-do+ACo- make gearing for this kind of
power. Typical steamships use reduction gears between the IP/LP turbines
(in thousands of RPM) and the main shaft (hundreds of RPM). And smaller
gearing between the HP and IP turbines. Bull-gears, the final output
gear
connected to the propeller shaft are large with double helix cut. Often
use
double-reduction with 'quill' shafts between successive gear stages.

Saw more than one bull gear get some broken teeth ground out. Didn't
replace the teeth, just ground down the sharp edges so they wouldn't wear
into the low-speed pinions (some sailors didn't believe the rules about
FOD).
On the ships I saw, the access ports to the main gear were sealed with
huge padlocks, and only the Chief had the keys. The gears are just too
tempting a tagret for sabatoge.

Yep. But when the sailor has a preventative maintenance procedure to go in
and take some measurements, if they aren't careful about restraining all the
things about their person, some genuine accidents do happen. And if the
sailor is too scared of the 'chief' to admit anything, then it gets left
inside. Eventually, with the motion of the ship and all, it gets ground up
in the gear. Leaving some damaged teeth behind.

daestrom


In the US Navy I was in, ships reduction gears where not opened except for very
carefully planned evolutions.+AKA- All tools/parts/rags/etc. were logged in and logged
back out of a "clean" area around any open reduction gear cover. Any time a cover
was open an armed guard was placed on it to prevent any/all possibility of damage
to the gear. Opening up an red. gear was/is a very rare evolution and is usually
watched closely by the Engineer Officer, the M division officer, and possibly the
ships' Captain.
In addition, the lube oil low pressure alarm for the reduction gear energized a
siren that could wake up the dead two area codes away, just to give an indication
serious even the possibility of damage to the gear is considered.
It was easier for two missile techs to do PMs on a Polaris missile than it was to
get permission to open an inspection cover on the boats' reduction gear.
ARM

Yep, the same as my US Navy. But the lower-level watch changes the main
lube-oil strainer once a watch. Care to guess what sort of things can be
dropped into a strainer housing while the strainer is removed? Even just
buttons off your sleeve or a pair of dolphins off your shirt. Not always
deliberate, but lets face it, it happens. And the gears chew em up and
grind em to bits. But that leaves a mark on the gear.

Ditto for the lube oil sump when its open for inspection/cleaning. The
close-out of the sump is signed off by an officer. Some junior officers
don't bother to leave the ward-room to perform that inspection.

Navy has been using FOD (Foreign Object Damage) prevention practices for a
long time. Yes, the engineer has the key to the locks on the reduction gear
and the sailors setup a tent over the gear and go through a lot to put
lanyards on all tools, and log everything in and out. But guess what, sh**
still happens.

daestrom

 

[daestrom]

Second try. Sorry about the HTML, Mozilla and I haven't come to terms
yet.
ARM



In the US Navy I was in, ships reduction gears where not opened except
for very
carefully planned evolutions.+AKA- All tools/parts/rags/etc. were logged
in and logged
back out of a "clean" area around any open reduction gear cover. Any
time a cover
was open an armed guard was placed on it to prevent any/all possibility
of damage
to the gear. Opening up an red. gear was/is a very rare evolution and is
usually
watched closely by the Engineer Officer, the M division officer, and
possibly the
ships' Captain.
In addition, the lube oil low pressure alarm for the reduction gear
energized a
siren that could wake up the dead two area codes away, just to give an
indication
serious even the possibility of damage to the gear is considered.
It was easier for two missile techs to do PMs on a Polaris missile than
it was to
get permission to open an inspection cover on the boats' reduction gear.
ARM

Depends on the situation I guess. IMA and 'depot' level maintenance opens
them up fairly routinely. But like I mentioned in my other post, the lube
oil system isn't so tightly controlled. The strainer is swapped every watch
by 'lower-level louie'. And when the sump is opened up for clean/inspect,
it is usually some junior officer that does the close-out inpsection (not a
very easy job to do).

Small crap *does* get in them despite all the precautions. Doesn't put a
gear OOC, but does leave its 'mark' on things. Buttons, 2nd-class metal
'crow' insignia, dolphins, 'tweakers', you name it. Some identifiable
remains, some just bits of plastic/metal.

daestrom

 

[daestrom]

Yep, but surely most proper geeks and engineers would have learned it from
Star Trek... uh... VI, I think it was?

Yes, "The Undiscovered Country". When coming up with an excuse why the
Enterprise could not return to base as ordered, the young female Vulcan
explains the Dutch history of the word.

daestrom
P.S. And yes, a 'sabot' is also a drop-away casing around irregularly
shaped objects used to make them fit in a gun barrel.