Vibration Monitor (Hyde, Wanttaja?)

Pete Schaefer wrote:
"Ernest Christley" wrote in message
om...

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.


How much would someone pay for the software to analyze this data? Also,
you'd probably need structurally integrated sensors, which would have to be
strong enough to support the loads. This would be a pretty tough engineering
problem in itself.



??? analyze ???
What analysis would you want to do other than to look a the relative
strains at a few distinct points. You'd like a bell shaped lift curve
on the prop, same as for a wing. I would pay $0 dollars for software
analysis, and opt for plotting the values on a sheet of graph paper with
a pencil. Well, that's not EXACTLY true. I'd probably use Gnumeric
(open source spreadsheet), as it would produce a much prettier graph
that I would.

Mind you, I'm talking a home carved wood prop here. Build in a little
pocket for the probe. Keep carving until one gives you the perfect profile.


Miniature temp probes and air pressure sensors that you can stick all
over the place.


More software. Sure it could be done, but cheaply enough for the average
home builder?

Why the software again. Danm, man, what do you think people did before
Intel came along with their little 4-bit wonder. You're engine isn't
cooling like you want it to. The way to see what you need to fix is to
map out pressures in and around the radiator system (I'm building a
water cooled auto-conversion. Please be patient with the radiator
thing.) The current way is to run water lines all over the place, duct
taping them to the side of the plane to get them back to the cockpit so
that you can measure all the relative water columns. No fancy analysis
is needed. Either you have a few inches of pressure across the radiator
cores, or you don't. Move the sensors around to find out where the high
pressure areas are.



Vibration sensors stuck inside control surfaces and different parts of
the skin. Early warning system for flutter.


Might be really expensive to get the signals characterized well enough for a
warning system.

Do you have a squelch knob on your radio? Do you have to run incoming
signals through a laborious data analysis before you decide where to set
said squelch? No! You just turn it up till the background noise stops.
Same here. If you hit flutter, the intensity will increase
dramatically, just like the occasionaly noise gets through the squelch.

As I said in my original post, it will probably give you just enough
time to kiss your butt goodbye, but flutter isn't always noticed for
what it really is and it does't always catastrophically destroy the
airplane. Sometimes it beats the airplane to death slowly. If the
'flutter squelch' from the t-tail always goes off as you hit 140kts and
dies back down as you pass through 150kts, it might be a clue that you
should rebalance the t-tail or avoid 145kts as a minimum.



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.


There's a ton of stuff stopping people from doing this right now. It's
money. None of the stuff you've mentioned is even remotely innexpensive. I
know people who've researched this stuff with the wired sensors for several
years, and haven't gotten much of it out of the lab. Yeah, with steady
improvements in computational fluids, finite element, mems tech, sensing
tech, etc., this stuff will be eventually packaged into something us
home-builder types can afford to use. However, most of it is still too
damned expensive, manpower intensive, and technically immature for even the
military to employ on huge aircraft development programs like JSF. By the
time this stuff really becomes generally available, I'm sure there will be
something better than blue tooth around.


I say those people are asking for too much. If you want the computer to
tell you exactly what's wrong, I'll agree with you all day long that
it's not economically possible with todays technology. If all you want
is a little information about what's going on around you (with the human
doing the divining), the cost is well under $500 (for wired sensors,
don't know about BlueTooth).


--
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)."