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Vibration Monitor (Hyde, Wanttaja?)



 
 
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  #51  
Old March 28th 05, 05:43 PM
nafod40
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Pete Schaefer wrote:
OK, if all you want is to record data, then yeah, whatever you want to use
is just fine as long as you can keep it from interfering with any critical
functions on your plane. However, debugging all the potential EMI stuff
could be hell just to get things to work.


I hate cables. They are a gawdawful pain to manufacture, install, even
worse to troubleshoot, and hell to fix. Installing new ones to odd
points on a plane is sometimes impossible. I flew the E-2C (whistling
s%$# can) and most of our class alphas were due to cables abrading and
causing shorts, wandering signals, fires, etc. Obviously the bad things
came from the power-carrying cables failing, but everything in the
bundle went south when they did.

EMI is obviously an issue, in ways I don't understand since I'm not a
tron-bender, but the idea that you could plunk down a sensor and have
*no* additional wiring whatsoever appeals to me. I wonder how much wire
weighs and costs in the typical airplane? What are the EMI issues for
your Mark I Mod 0 homebuilt? Nav system, obviously. What else? Sounds
like an experimental airplane kind of thing to me.

A company a friend of mine owns is developing the self-powered sensors,
so I'm familiar with the work. The ones they sell now are bigger and (I
think) battery-powered, but they are installing them on Navy ships,
which have emmisions and EMI concerns too.

http://www.rlwinc.com/

  #52  
Old March 28th 05, 09:04 PM
Frank van der Hulst
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Pete Schaefer wrote:
Frank:

I do have quite a clue about EMI, and clearly have a better clue than you
about systems engineering in general. Here's a question for you:

Why bother?


For the same reason that we build planes instead of buying them.

If you're trying to cert bluetooth for aviation, maybe with the thought of
selling some other bluetooth product that you think you can make a big chunk
of cash with, then, yeah, maybe going off to play with bluetooth on your
airplane makes sense. Personally, I can't see it. Maybe it makes sense for
using it to reprogram boxes on your airplane, but to go to the extent of
making it useful/safe in flight....nah. Way too much effort for too little
return, given that the inclusion of an RS-232 port is so freakin' easy.


I agree totally. except maybe about RS-232. I suggest that some sort of
current-based rather than voltage-based signalling would be more
noise-immune. Bring back 20mA current loop! :-)

If you have some other goal in mind, maybe some other sensing or data fusion
tech (e.g. may you have a huge array of air data sensors for some advance
stall detection method), then you have to look at whether or not the tech
risk buys you something that you can't get otherwise. Why bluetooth rather
than the 1/2 dozen other wired data communication protocols (e.g. 1392, .
422, 232, 485, CAN, etc.) that are out there?


The TWO key ideas in the proposition (wasn't mine, BTW) were wireless
comms and self-powered. If you can do BOTH of those, then wired comms
and power is best. Wireless comms has been pretty much solved. For
example, I saw a projection in an engineering mag that within 25 years
wireless will replace wired as the cheapest comms technology to the home.

But without "self-powered" it is pointless. Are there any devices out
there that can turn (e.g.) vibration into *useful* amounts of electricity?

I get rather frustrated with people who get really !@#$ing enamored with
technologies for implementation and loose sight of what their goals are.


Hmmm... so what are *my* goals? Maybe I want the geekiest plane on the
block? I suggest that one or other of your 4 beers has introduced some
patronisation (as well as abrasiveness) into your system.

All
too often, risk variables get introduced where none is warranted, resulting
in zero or negative value added.


I'll choose what risks are warranted on *my* project, thanks.

I beat on my guys daily about issues like
this. (Kelly Johnson (...yeah, I work at that place.....) had a lot to say
about where it was acceptable to take project risks..too bad so much of it
never got captured in "the rules").


This is fine where *you* get to set the goals.

So, back to Blue Tooth....

Why bother?


*With* self-powered devices, it gives options not available via wired
systems.

For data collection, I've already got a half-dozen options in my hip pocket
that I know will work just fine with very well understood EMI issues that I
know how to mitigate. What's my goal? Blue tooth airplane or getting the
data for some other purpose?

I have very little room for Geek Factor on any airplane that I'll ever
build. If it can't buy it's way on (I'd lump Blue Tooth in here), then !@#$
it.


Pete

P.S. I just got done with a 5 hour drive and am tired as all !@#$. I've got
4 beers in me to diffuse stress. Please forgive my abbrasiveness. I'm not
really that bad of a guy. I just don't want people to pursue ideas that
will get them killed.


Hey, I prefer to talk straight too. And also don't want people to kill
themselves. But if people don't experiment with Experimental category
aircraft, then nothing is going to change.

Frank
  #53  
Old March 28th 05, 09:19 PM
nafod40
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Frank van der Hulst wrote:

*With* self-powered devices, it gives options not available via wired
systems.


Couple of sources. This is a hot research area.

http://www.sandia.gov/media/NewsRel/...eredsensor.htm

http://www.perpetuum.co.uk/

  #54  
Old April 2nd 05, 12:47 AM
Ernest Christley
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Frank van der Hulst wrote:

Why bother?



*With* self-powered devices, it gives options not available via wired
systems.


Even if you have to run 12V to it, in a metal airplane that will only be
one wire and one connection. Assuming they can build a wireless device
that can stand up to typical airplane abuse for a while*, this would
make for a much simpler and safer installation. At these power levels,
the EMI issue is a red herring that would be easily defeated with a
$0.98 roll of aluminum foil, and once defeated on the ground the
problem isn't likely to pop back up in flight (like loose cabling will).

IMHO

*It seems that your standard store bought router is designed to die
after a few years. I wouldn't trust this quality control with my
comfort. I barely trust it with my ability to read this newsgroup.


--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."
  #55  
Old April 2nd 05, 04:09 AM
Pete Schaefer
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So, what things on the airplane are you guys going to replace with
self-powered blue tooth devices?


"Ernest Christley" wrote in message
om...
Even if you have to run 12V to it, in a metal airplane that will only be
one wire and one connection. Assuming they can build a wireless device
that can stand up to typical airplane abuse for a while*, this would
make for a much simpler and safer installation. At these power levels,
the EMI issue is a red herring that would be easily defeated with a
$0.98 roll of aluminum foil, and once defeated on the ground the
problem isn't likely to pop back up in flight (like loose cabling will).

IMHO

*It seems that your standard store bought router is designed to die
after a few years. I wouldn't trust this quality control with my
comfort. I barely trust it with my ability to read this newsgroup.



  #56  
Old April 2nd 05, 05:38 AM
Frank van der Hulst
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Pete Schaefer wrote:
So, what things on the airplane are you guys going to replace with
self-powered blue tooth devices?


First thing would be Bluetooth headsets... no more cords tangling round
the cockpit.

Next would be various engine instruments... EGT, CHT, etc.

Maybe move the entire radio receiver out to a wingtip or somewhere well
away from the engine's RF noise. But I can't see that being
self-powered. Perhaps we could use Tesla's beam-power technology to run
those.

Frank
  #57  
Old April 2nd 05, 07:12 AM
Ernest Christley
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Frank van der Hulst wrote:
Pete Schaefer wrote:

So, what things on the airplane are you guys going to replace with
self-powered blue tooth devices?



First thing would be Bluetooth headsets... no more cords tangling round
the cockpit.


That's a good one. Keep an old pair if wired sets stuck in an
accessible hole someplace...just in case.


Next would be various engine instruments... EGT, CHT, etc.


Perfect. If the signal dies, the plane won't know it. The Cherokee I
trained in didn't even have a working EGT.


Maybe move the entire radio receiver out to a wingtip or somewhere well
away from the engine's RF noise. But I can't see that being
self-powered. Perhaps we could use Tesla's beam-power technology to run
those.

Frank


Oooh. You just lost me on that one. To much complication with the radio
to human interface there. You've got a device in front of the pilot to
select a station, which must transmit it to a device out on the wing,
which has to recieve and interpret it correctly, then transmit the
correct station's signal back over bluetooth. You'd still have to run
signal wires for the physical backup. I just don't see the advantage
when remoting the antennae is all that's necessary to avoid the engine EMI.

How about stress monitors built into the prop (I have no idea if anyone
makes such a thing). Would help you to carve a perfect prop.

Miniature temp probes and air pressure sensors that you can stick all
over the place. Would make it real easy to map out the pressure regions
on the airplane and design a better cooling system or decide if wing
modification would be necessary/beneficial.

Vibration sensors stuck inside control surfaces and different parts of
the skin. Early warning system for flutter. Might only give you time
for a short prayer, but it may save your butt if you can react quick enough.

Nothing is stopping anyone from doing any of this with wired sensors.
It would just be cleaner and easier if the wire can be left on the spool.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."
  #58  
Old April 2nd 05, 07:53 AM
Frank van der Hulst
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Ernest Christley wrote:

Maybe move the entire radio receiver out to a wingtip or somewhere
well away from the engine's RF noise. But I can't see that being
self-powered. Perhaps we could use Tesla's beam-power technology to
run those.


Oooh. You just lost me on that one. To much complication with the radio
to human interface there. You've got a device in front of the pilot to
select a station, which must transmit it to a device out on the wing,
which has to recieve and interpret it correctly, then transmit the
correct station's signal back over bluetooth.


This kind of stuff is bread-and-butter for Bluetooth. Remember that one
of its original design goals was moving (high-quality stereo) audio in
real time from a player to headphones. Sending channel-select signals in
the opposite direction isn't a biggy either... Bluetooth devices are
continually communicating digitally amongst themselves.

You'd still have to run signal wires for the physical backup.


Why? The airplane will keep flying if the radio fails. Granted that,
depending where you live and fly, losing access to your radio could be a
bit, um, difficult. But, for many, a radio isn't a necessity.

I just don't see the advantage
when remoting the antennae is all that's necessary to avoid the engine EMI.


You said it yourself in your last sentence: It would just be cleaner and
easier if the wire can be left on the spool.

How about stress monitors built into the prop (I have no idea if anyone
makes such a thing). Would help you to carve a perfect prop.


Prop blade pitch control... a motor in the spinner to adjust pitch,
controlled via Bluetooth. No hollow crankshafts and oil pressure
systems, no slip-rings.

Frank
  #59  
Old April 2nd 05, 08:17 AM
Scott Skylane
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Frank van der Hulst wrote:
/snip/
Prop blade pitch control... a motor in the spinner to adjust pitch,
controlled via Bluetooth. No hollow crankshafts and oil pressure
systems, no slip-rings.

Frank


Eh? How would the motor be powered, batteries? I'm not sure how long
reasonably sized batteries would work. And what about centrifugal force
issues?...

Happy Flying!
Scott Skylane
  #60  
Old April 2nd 05, 08:39 AM
Pete Schaefer
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"Frank van der Hulst" wrote in message
...
First thing would be Bluetooth headsets... no more cords tangling round
the cockpit.


That would be pretty nice. But now you need batteries in your headset to
power the audio amp.

Next would be various engine instruments... EGT, CHT, etc.


I guess you'd need some devices (i.e. wires) for routing the signal through
the firewall or around it. How much lighter would this be than, say, a
twisted pair for CAN?

Maybe move the entire radio receiver out to a wingtip or somewhere well
away from the engine's RF noise.
But I can't see that being self-powered.


The receiver could be, but not the transmitter. An antenna wire is probably
a lot lighter than running power out, so I guess that would need to stay in
the cockpit.




 




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