In a message dated 12/26/2007 2:59:26 P.M. Pacific Standard Time,
brent@regandesigns.com writes:
the
humility to accept the results of testing and the wisdom to mitigate the risk.
Hamid is a very good engineer. Ignore his advice at your peril. If you need a
sycophant, you are looking in the wrong place.
I guess I missed the humility part...
Look gents, there are many ways to skin a cat and you two (Hamid and daddy
Brent) are VERY confident regards yours. Fine, but my comments
started from another point of view that I would suggest is still worth
consideration, to wit:
I like the Dynon as a backup to a certified EFIS on a Lancair IV with a
properly designed power production/distribution system--my original statement
when I entered this string. It was good enough for the fine ENGINEERS at
Scaled when WE flew SS1 to space, it never failed and it was praised by Mike
Melvill, the world's first civilian astronaut. But that really isn't the
point either. The point is the design process in total: a reliable
panel is the result of system design philosophy that begins with some
questions:
1. Is the engine electrically dependent?
2. Is the panel electrically dependent?
If yes to either, then really study Nuckolls.
Include the ability to isolate and monitor each of the generation and storage
elements. Include a current limiter for each of the alternators.
Include all the normal over voltage protection and low voltage warning
devices. Be able to monitor load. Interestingly the Chelton does NOT
have a current measuring capability so add one if you are using that all
singing, all dancing Hamid/Brent EFIS. (a wonderful piece of gear I am
very glad to have on my panel) I located a load meter/volt meter in my
normal field of view and have a low voltage light that illuminates within a few
seconds of an alternator failure.
3. Is the panel providing information or just a bunch of data?
Work to make it simple--you will have plenty to
keep you busy without having multiple redundant displays everywhere begging for
attention. Remember many flew for decades with a fraction of the
information provided by one good EFIS--the panel is a bad place for gadget
overload.
4. Contain your redundancies--a subset of the above.
After trying to design in simplicity I still had
FOUR separate sources of heading information when I considered where to put the
standby compass. Sooo why would I add a fifth, other than to appease an
inspector who doesn't really understand the regs.
5. Are you really weather current: IMC not just IFR?
If single pilot IMC in a complex airplane
is your goal, a good autopilot is a fine place to spend some
money--maybe worth more of your consideration than the shape of backup
instruments. Remember a good autopilot provides the same attitude data
while it flies the approach.
6. If you do all that then your airplane, not just your
panel, will have power when you need it so really an electric gyro as a
backup attitude indicator or an electric mini EFIS is a flip of the coin.
My decisions after the above resulted in a single alternator and two
Odyssey batteries as I stated previously. I like multiple batteries
because I am confident their technology will continue to develop rapidly as
hybrid this and that's come to the market place and I will be able to benefit
with easy retrofits (no body is spending much money on next generation
alternators that can be screwed into TSIO-550s). I have a current limiter
and a B&C voltage regulator with very reliable protection and warning
circuitry. I have one main bus, two battery switches, one LSE only on each
battery bus and an alternator switch so everything is deselectable for trouble
shooting. I do not have an avionics switch but do have an EFIS mstr for
the Chelton suite as well as an autopilot mstr for the TruTrak suite. I do
not have a second alternator because I did not think it worth the addition of
gears in the accessory section of the engine (no mags, no stby alt, no vacuum
pump, no accessory gears) as well as a second voltage regulator and associated
wiring. I have many fuses and few CBs.
Mine is the yellow panel, the first in the Lancair
Avionics IV/IVP gallery. The left insert is dedicated to the dual LSE
ignitions, the rest is self explanatory I think. Having flown as a USAF
combat, fighter and test pilot for twenty years and worked at Northrop as
analyst, engineer, manager and executive for the YF-23, B-2, JSF, and many
advanced projects for 15 as well as served on the board of Scaled, I think it is
wonderful to have a panel with NO round gauges--truly 21st century stuff!
All works fine and plays together well--providing information not just
data--pretty much right from the start. My first homebuilt was a LongEZ
that took years to sort out; I built this LIV mostly alone in 6 years and one
week and accumulated 146 hours the first year, about 10% IMC. I think that
speaks well of the airplane and the systems design and integration--a tip of the
hat to the team at Redmond as well as Mr Nuckolls. From my point of view
the LIV is the best, most efficient cross country airplane available today--and
it is a joy to fly and goes really fast!
paul, N94PT