Today's Message Index:
----------------------
1. 06:09 AM - Re: Re: Appendix Z (Robert L. Nuckolls, III)
2. 06:38 AM - Magneto tacho signal (Dennis Johnson)
3. 07:44 AM - Re: Magneto tacho signal (Robert L. Nuckolls, III)
4. 08:03 AM - Re: Magneto tacho signal (Robert L. Nuckolls, III)
5. 09:54 AM - Re: Magneto tacho signal (Ed Holyoke)
6. 03:42 PM - Re: Magneto tacho signal (Kelly McMullen)
7. 06:29 PM - Re: XeVision HIDs (Speedy11@aol.com)
8. 07:16 PM - Re: Bells and Whistles (Speedy11@aol.com)
9. 07:40 PM - Re: XeVision HIDs (XeVision)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
At 10:39 PM 10/16/2009, you wrote:
>
>Thanks Bob, do you have a rough idea when it will be available? I'm hoping
>to start the electrical this spring.
>Tim
Certainly this winter. I'm still moving, building benches
and shelves, sorting keep-it/sell-it stuff between two
households and sorta remodeling the Wichita house as
I go. Want to get my kids moved into it before Thanksgiving.
We're playing musical houses right now!
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Magneto tacho signal |
Hi Bob B.,
I also have one LightSpeed electronic ignition and one magneto. I have
a Grand Rapids engine information system. I wired the engine
information system to accept either the RPM signal from the electronic
ignition or the RPM signal from the magneto, controlled by a toggle
switch*.
I never use the toggle switch and use the RPM signal from the electronic
ignition as the only input. As you said, that means my RPM goes to zero
when I briefly switch off the electronic ignition during the pretakeoff
runup . That has never been a problem for me because I rely on exhaust
gas temperature on each cylinder to confirm that all spark plugs powered
by each ignition system are firing. I believe that is a better method
than measuring the RPM drop on a single ignition system, which was
probably used before airplanes had EGT readings on each cylinder.
The electronic ignition has been 100% trouble free so far, but if it
failed in flight, I would lose my tachometer reading. I have enough
experience with my airplane by now that I don't think I'd have any
difficulty continuing flight to my planned destination without a
tachometer.
Best,
Dennis
Lancair Legacy, nearly 300 tach hours
*The Grand Rapids EIS must be configured correctly for the type of tach
signal that it receives. I configured mine for the signal produced by
the electronic ignition, which is different than the signal produced by
the magneto. So if I ever switched the toggle switch to display RPM
from the magneto, the actual number would be way off, but by a knowable
amount. In nearly 300 hours of flying, I've never actually used the
toggle switch to select RPM from the magneto and if I had it to do over
again, I would leave it out of my design. Higher parts count,
additional complexity, another point of failure.
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Magneto tacho signal |
At 02:05 AM 10/17/2009, you wrote:
>Bob,
>
>Got the same setup and have an Electronics International tach which
>looks at the signal from both ignitions and displays the one still
>turned on during ignition checks. That way I can see the RPM drop on
>both sides. Don't know who makes your glass, but you might want to
>check with them and see if their device can do that, too.
Good idea. I think most electronic/glass tachs
offer dual sensing capability.
> When we got the plane, the tach only read the Lightspeed. The tach
> dropped to zero when the Lightspeed was switched off. It wasn't
> optimal, but sorta got used to not seeing the drop. I listened for
> it, instead. I eventually sent the tach back to the factory and had
> it re-rigged to display both. If I had to choose between the
> electronic ignition signal and the one from a transducer plugged
> into the tach cable hole on the engine, I'd take the electronic
> ignition - it's going to be more accurate.
Actually, the "accuracy" of tachometer signals
is dead-on irrespective of technology. These
are integer pulse signals of so many pulses per
engine revolution and are not subject to errors
of calibration. Now, reading a p-lead offers some
challenges with respect to lots of short spikey
signals riding on the signal of interest but that's
a simple filtering issue that does not affect the
accuracy of the signal of interest.
>I'm not sure what signal there is to sense while the mag is grounded.
For a p-lead sense tach, this is right-on. Some models
of tachometer have a vent-plug in the side you can
replace with a hall or electro-magnetic transducer
that watches poles of the magneto's magnet fly by.
This sort of "mag pickoff" is functional whether or
not the magneto is operating.
>To change the subject slightly, I've always wondered about having
>the backup ignition be less reliable than the main. Sure, a magneto
>doesn't need the electric system to keep working - until it quits
>working right, anyway, like mine did yesterday. Did the 500hr
>inspection on it less than a hundred hours ago and the brand new
>condenser took a crap and took out the points. My next plane will
>have dual Lightspeeds. Ours hasn't changed a degree in timing in the
>6+ years we've been flying it. Say that about a magneto.
"Reliable" or "service-life"? Had this mag been
functioning as-expected for 500+ hrs? I'll suggest
there's value in making a distinction between
COMPONENT reliability/service-life and SYSTEM
reliability. System reliability is calculated
by plotting all critical failure modes on a
"reliability tree" and performing the math
that predicts probability of total loss of system
(the whole airplane) function when viewed through
the relatively narrow window of one flight cycle.
System reliability is enhanced when you have dual
sources for critical functionality . . . i.e. dual
ignition. The question to be pondered is, "what is
the liklihood that I loose BOTH systems in any one
tank full of gas?" I'll suggest further that
your experience with the magneto has been pretty
much on a par with the rest of the folks in the
industry. Changing it out would not mathematically
improve your system reliability.
With respect to "mag drop" . . .
The engine slows down slightly when deprived of
half of the sparks for ignition due to an apparent
retardation of spark. This happens because mags
are fixed timing to accommodate worst case
operations (sea level, full power). When you install
one or two electronic ignitions that watch
manifold pressure and appropriately advance the
spark, you don't get as pronounced (if any) mag
drop when shutting one ignition off. The the only
reason NOT to fly when presented with no (or
un-symmetrical) mag drop is to investigate a
"shift in timing". Such events suggest sloppy
work by the mechanic who last tightened the
mag attach hardware.
It's far more important to simply know that
each ignition source functions independently
of the other irrespective of how much the
tachometer reading changes for each condition.
Bob . . .
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Magneto tacho signal |
<snip>
>The electronic ignition has been 100% trouble free so far, but if it
>failed in flight, I would lose my tachometer reading. I have enough
>experience with my airplane by now that I don't think I'd have any
>difficulty continuing flight to my planned destination without a tachometer.
Aha! I think you could do it too. Our flight instructors
never gave us lessons in what was NECESSARY for low risk
flight, what was USEFUL for flight and what one could
do to cope loss of one or more instruments.
I used to have guys come to 1K1 to rent my airplanes
and when going for a get-acquainted ride with them,
it was not uncommon to have a prospective renter who's
eyes were glued to the instruments . . . or at least
spent very little time outside the cockpit.
One fellow was so concentrated on watching the needles
I borrowed one of our instructors set of block-out
patches and covered EVERYTHING on one of our
C-150's and invited him to go flying with me. I was
able to demonstrate comfortable operation of the airplane
without knowing what ANY of the numbers were. But
that operation was based on staying well inside
the airplane's limits by referencing things I had
explored about visual cues for pitch and power simply
based on where the throttle was and what the engine
sounded like and position of the nose with respect
to the horizon.
I got to go retrieve the company A36 when one of
our pilots left the airplane on the Dodge City
airport because the "tach had died". He didn't know
enough about the airplane to even check the tach
cable fittings (the one on the engine had come
loose). But even if we hadn't fixed the tach
before bringing the airplane home, it would have
been no big deal to fly it back with a dead tach.
One of the really nice things about the OBAM aviation
community is that builders are inherently more
knowledgeable about their airplanes but many
of us still drag a lot of the "padded cockpit"
environment with us. Airplanes don't crash
because a gage quit, airplanes crash because
the pilot lost his connection with the machine.
You can't loose something you never had.I would
encourage everyone, starting with their fly-off,
to explore flight operations with all manner of
degraded instrumentation.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Magneto tacho signal |
Howdy,
Robert L. Nuckolls, III wrote:
> At 02:05 AM 10/17/2009, you wrote:
>
> "Reliable" or "service-life"? Had this mag been
> functioning as-expected for 500+ hrs? I'll suggest
> there's value in making a distinction between
> COMPONENT reliability/service-life and SYSTEM
> reliability. System reliability is calculated
> by plotting all critical failure modes on a
> "reliability tree" and performing the math
> that predicts probability of total loss of system
> (the whole airplane) function when viewed through
> the relatively narrow window of one flight cycle.
Reliable? Functioning as expected? Well, yes.... if it is expected to
foul plugs and deliver rough mag checks requiring more lean running at
high RPM to clear up before taking off. Granted, that doesn't happen
every time as we operate very lean on the ground to try and minimize
this kind of behavior. Requiring much more maintenance? I guess that's
expected, too. Cleaning and gapping plugs takes an inordinate amount of
time. All that lead that gets stuck down by the insulator doesn't come
out easily. I just buy new $3 plugs every year for the Lightspeed and
done (and the old ones are never lead fouled, anyway). The timing always
changes between annuals because of wear on the points and must be reset.
And no, it didn't work for 500hrs this time. At the 500hr inspection
(yet more maintenance not required on an electronic ignition), the wear
items (points, condenser, bearings, seals - none of which exist on the
crank sensor Lightspeed) were replaced and this was only about 80hrs
before failure. By the way, this is the Bendix mag. It's meant to be
rebuilt as many 500hr cycles as you want, unlike the throwaway Slick
mag. 80hrs is way too soon for problems to occur, yet sometimes they do.
>
> System reliability is enhanced when you have dual
> sources for critical functionality . . . i.e. dual
> ignition. The question to be pondered is, "what is
> the liklihood that I loose BOTH systems in any one
> tank full of gas?" I'll suggest further that
> your experience with the magneto has been pretty
> much on a par with the rest of the folks in the
> industry. Changing it out would not mathematically
> improve your system reliability.
Changing it out with another mag certainly wouldn't improve system
reliability. Comparing my experience with the magneto to my experience
with the electronic ignition, I think my system reliability would
improve, measurably, by replacing it with an EI. The EI never fouls
plugs, never (so far) requires unscheduled maintenance. The maintenance
that it does require, such as checking timing and replacing plugs at
annual, is quick, cheap and easy. I could even re-use the plugs. They're
always in great shape after a year and a couple hundred hours of use.
If the only reason to have 2 ignitions was for backup - maybe. The
problem is that these engines with big ass pistons really need 2
functional ignitions to get the flame spread over with before the moment
has passed to make useful power. The 25 degree BTDC timing (fairly
standard, although there are exceptions) is a compromise designed to
maintain a margin of safety from detonation at full power and sea level.
The EI fires at the same timing under those conditions. At high altitude
(read low manifold pressure), 25 degrees is way too late for best power
and there is no danger of detonation, so the EI advances to as much as
40 degrees BTDC. This puts the moment of maximum cylinder pressure at
the crank position of greatest leverage (about 19 degrees ATDC). The
magneto fires 15 degrees later than the EI and is not much help. The
role of the magneto under these conditions is truly as a backup system.
The EI also puts out a much hotter spark fired over a larger spark plug
gap. At lean mixtures especially, this ignites the mixture more
reliably. Klaus claims another 5% improvement in fuel economy with a
second EI. If much of your flying is in cruise, I'd think this is
probably about right. It'd probably take a while to pay for the new
ignition that way, though.
>
> With respect to "mag drop" . . .
>
> The engine slows down slightly when deprived of
> half of the sparks for ignition due to an apparent
> retardation of spark. This happens because mags
> are fixed timing to accommodate worst case
> operations (sea level, full power). When you install
> one or two electronic ignitions that watch
> manifold pressure and appropriately advance the
> spark, you don't get as pronounced (if any) mag
> drop when shutting one ignition off. The the only
> reason NOT to fly when presented with no (or
> un-symmetrical) mag drop is to investigate a
> "shift in timing". Such events suggest sloppy
> work by the mechanic who last tightened the
> mag attach hardware.
Asymmetrical mag drop is one thing. As you said, this is to be expected
with 2 different types of ignition. Rough running on one ignition is
something else and indicates fouled plugs or another, possibly worse,
failure. This is definitely a good reason not to fly until cleared up as
you are now down to one good ignition. This raises the odds that you'd
have 2 failures on 1 tank of gas to an unacceptable level.
>
> It's far more important to simply know that
> each ignition source functions independently
> of the other irrespective of how much the
> tachometer reading changes for each condition.
Hear, hear. Another thing is: the traditional mag check at 1600 or 1700
RPM and full rich doesn't really tell you much about the true condition
of the ignition system. My magneto passed this check, yet ran rough in
flight, causing me to return to the airport. Not an emergency, also not
at all comfortable. A more thorough check can be done at altitude,
leaned. This shows up problems you might not notice on the ground check.
Unfortunately, I didn't do this before landing on the prior flight.
Pax,
Ed
>
> Bob . . .
> *
>
>
> *
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Magneto tacho signal |
Well, there is something wrong, as I never have to touch my Bendix mags
in less than 400 hours, and then only to tweak the timing by a degree or
so. I don't need to burn off deposits at runup. I do routinely pull the
bottom plugs at annual and clean them...top plugs every other year, just
to get rid of the small amounts of lead. Your points should not wear
that fast. Either the condenser isn't right, allowing faster pitting, or
the cam isn't properly lubed allowing it to wear. 600-700 hours between
inspections for new points, etc. is what I have been getting with my
S200 series 4 cylinder mags. Sure, I would like variable timing, but the
total improvement with both ignitions optimized is only going to be
about 5%. Any claim for more is dreaming. You might consider having a
reputable magneto specialty shop go through that mag. There may be more
bearing or rotor wear allowing slop in the rotor, or something else wrong.
Ed Holyoke wrote:
the relatively narrow window of one flight cycle.
The timing always
> changes between annuals because of wear on the points and must be reset.
> And no, it didn't work for 500hrs this time. At the 500hr inspection
> (yet more maintenance not required on an electronic ignition), the wear
> items (points, condenser, bearings, seals - none of which exist on the
> crank sensor Lightspeed) were replaced and this was only about 80hrs
> before failure. By the way, this is the Bendix mag. It's meant to be
> rebuilt as many 500hr cycles as you want, unlike the throwaway Slick
> mag. 80hrs is way too soon for problems to occur, yet sometimes they do.
> If the only reason to have 2 ignitions was for backup - maybe. The
> problem is that these engines with big ass pistons really need 2
> functional ignitions to get the flame spread over with before the moment
> has passed to make useful power. The 25 degree BTDC timing (fairly
> standard, although there are exceptions) is a compromise designed to
> maintain a margin of safety from detonation at full power and sea level.
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: XeVision HIDs |
I agree that the 4000-5500K range is ideal because it is closest to
"daylight," but I always like the "slightly "bluish" color temp of my Audi TT
HIDs and that is likely what I will change to next time. As I recall those
are about 6500K. I know the 4200K bulbs produce the most light, but my eyes
like the blue tint. I do like the brightness of my lights - a number of
people have asked me about them. The wig-wag LEDs add to the overall effect.
I was unaware of the color shift on the 4200K bulbs. I only have 20 hours
on them, so I'll watch for the change. I may like them better after the
shift.
Stan Sutterfield
do not archive
Optimal color temp for HID is 4000-5500 Kelvin. As the 4200K bulbs (as you
have)
age from new they color shift towards 5000K. This takes 50-100 hours burn
time
to occur.
What is wrong with the color output you have ???
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Bells and Whistles |
Bob,
I understand and concur with your concern.
For example, I prefer manual flaps over electro-whizzy ones, but I can't
argue that there are many applications where powered flaps (electric or
hydraulic) are desirable. There are failure modes associated with powered
flaps that may cause potentially unsafe situations. However, those failure
modes are considered an acceptable risk when weighed against the convenience.
I have to then challenge you and suggest that having (as an example)
airspeed sensors that can disable powered flap activation when IAS is excessive
may be a convenience worth having despite it's potential failure modes.
That is not to say that said sensor need not be robust - I would assume that
robustness would be expected. I believe the application of such a sensor
to a perceived need could be worthwhile.
The Vertical Power concept takes this discussion to a new level. While I
prefer having manual activation of most of my switches and controls, the
Vertical Power ideas are certainly viable.
Experimental aviation is where many (if not most) advances in aviation
occur. I say lets continue to advance aviation by expanding ideas and
concepts - including new electro-whizzys. We don't have to stay with wing-warping
just because it resulted from a prudent development program. Although ...
maybe we need to consider it once again in today's environment. Hmmm ...
any experimental aviation nuts out there willing to rework the wing warp
idea?
Stan Sutterfield
The first question I always ask: "What's
the value added for this new electro-whizzy.
Does the value added more than offset the
cost of a prudent development program?"
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: XeVision HIDs |
If your car came with HID stock and you have not changed your bulbs to Chinese
bulbs, there is no way your car has 6000 or 6500K bulbs.
All cars come from the factory with 4200K bulbs. Your headlight projector may be
making it look bluer.
The highest DOT legal bulb color is 5000 to 5400K. These bulbs do not come in new
cars but are for replacement only to match an older aged bulb color that has
color shifted. Philips offers a 5000K, GE a 5100K and Osram a 5400K. Those are
the highest color bulbs legal in the USA for autos. All cars in the USA come
with 4200K bulbs.
The only TRUE 50 or 75 watt bulbs currently being made are about 4000K.
We have tested many of the Asian made (including Korea) bulbs, some TRY to handle
50 bulb watts but none do it very well. As for 70 or 75 watt, Only the Germans
have a track record or results with that bulb power level.
--------
LED still has a long way to go to compete with HID as a landing light. This is
true in terms of total lumens and reach (distance).
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=268377#268377
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|