Today's Message Index:
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1. 01:25 AM - Re: Direction Indicator Needs (GLEN MATEJCEK)
2. 02:18 AM - Re: Direction Indicator Needs (Stuart Hutchison)
3. 11:12 AM - Re Direction Indicator Needs (D L Josephson)
Message 1
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Subject: | Re: Direction Indicator Needs |
>
> Hi O.C.- RE:
>
> http://www.grtavionics.com/mini.html#Features
>
> is simply the indication of a remotely located magnetometer (which is
> available for the Mini-X and Mini-AP, but not the Mini-B) then I don't
> think
> that will meet the intended requirement of 14 CFR 91.205 (d) (9) criteria
> for a Gyroscopic directional indicator (directional gyro or equivalent).
>
>
> I'm curious as to why you are concerned this hardware would be
inadequate. It seems to me that it fits the bill and then some.
To reference what Ryan cited:
>
> The dynon d6 pilot guide says "Like a conventional gyro-stabilized magnetic
> compass, magnetic heading reacts immediately to turn rate so that heading
> changes are reflected immediately. It then uses magnetometer data over the
> long term to ensure that it remains correct. Additionally, heading is
> corrected for attitude so that it is accurate as you pitch and roll. "
> Sounds equivalent to a dg to me.
>
> This would be quite a bit better than a DG- It won't precess, doesn't
need to be manually synced to a compass, and there are no bearings to wear
out. If your concern relates to the display, there are many certified
drum-type DG's still flying today. That's not my first choice for a
display, but it does work.
Thoughts?
Message 2
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Subject: | Direction Indicator Needs |
G=99day OC,
We have the same issue in Australia, with policy anchored to antiquated
analogue designs. CASA, our FAA, was slammed by most sectors of the
Aviation community in submissions to the Federal Government review
(still underway) over recent months.
In my mind the installation should be =98no less safe=99
than existing IFR instruments. There is a LOT left to be desired in
many S/E Type Certified IFR aircraft that depend on a notoriously
unreliable single vacuum pump to drive the two most important flight
instruments on the panel, the attitude indicator and the DG, neither of
which are required to have a built-in failure flag. These two
instruments usually also drive the autopilot! The compass is fast
becoming totally obsolete alongside a certified GPS, perhaps several,
that measure point-to-point track. Among other things, magnetic heading
from the magnetometer helps calculate wind, but if you know the track
and groundspeed, who needs a wet compass?! Flying limited panel on the
=98backup=99 electric turn and bank indicator (which
actually indicates rate of change of heading, not roll and is gimbal
limited to about rate 1 or 2) is extremely difficult in rough weather,
which has resulted in numerous fatalities.
CASA has yet to agree that system safety can be achieved a variety of
ways, not the least by full redundancy. The Garmin 1000 is not fully
redundant, which is why there is a backup three-pack to complement the
PFD/MFD. A second AHRS, ADC and magnetometer would be required to make
the system fully redundant, but software is also vulnerable to latent
bugs and multiple systems can be expected to behave the same way under
the same preconditions, so alternative hardware or staggered software
versions seems like a good idea to me. CASA is wedded to outdated
TSO=99s, arguing that if a piece of equipment is required by the
Regs, then it must be approved in one of the recognised ways. In the
absence of a specific approval, in most cases, that means a TSO. CASA
don=99t seem to care that the most recent TSO for attitude
indicators was published via typewriter in 1959. We do not want Dynon,
AFS, GRT etc etc to required TSO=99s, nor is it necessary in order
to achieve the equivalent form, fit, function and quality intended by
the TSO.
Like the US, Australia will slowly adopt
=98performance-based=99 testing for equivalent functionality
of non-TSO flight instruments, but the authorities are moving at a
glacial pace. I think it is statistically significant that there are
thousands of Dynon, AFS, GRT etc etc systems being operated VFR in the
AB(E) community without systemic issues that would preclude them being
used for IFR. Heated pitots becoming overcome with trapped
moisture/ice are unhelpful for the IFR cause, but these are known issues
that can and will be overcome in due course. All this is in relation to
flight instruments of course. Communication/Navigation/Surveillance
(CNS) systems are a different matter and should be TSO=99d if we
expect to fly IFR in/around airspace with airliners and paying
passengers.
Cheers, Stu
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Owen
Baker
Sent: 11 June 2014 04:24
Subject: AeroElectric-List: Direction Indicator Needs
6/10/2014
Hello Aeroelectric and Avionics Listers, I know that there are many
technically smart people on these lists and I would like to enlist your
assistance.
Picture this situation: There are hundreds (maybe thousands) of EAB
(Experimental Amateur Built) IFR capable aircraft flying around with
vacuum driven mechanical spinning mass gyroscopic attitude and
directional indicators. A large percentage of these builders and pilots
would like to (or need to) replace those indicators with something
electronic (other than expensive electrical motor driven mechanical
spinning mass gyroscopic) in nature and remove the entire vacuum system
from their EAB.
Replacing the attitude indicator does not appear to be a big problem in
meeting the requirement of 14 CFR 91.205 (d) (8) =9CGyroscopic
pitch and bank indicator (artificial horizon)=9D since there are
several offerings available. Here are some:
http://www.dynonavionics.com/docs/D6_intro.html
<http://trutrakap.com/product/gemini-pfd/>
http://trutrakap.com/product/gemini-pfd/
<http://www.grtavionics.com/mini.html>
http://www.grtavionics.com/mini.html
<http://www.sandia.aero/?q=node/80>
http://www.sandia.aero/?q=node/80
But there does not appear to be available an electronic directional
indicator that would meet the 14 CFR 91.205 (d) (9) criteria for a
=9CGyroscopic directional indicator (directional gyro or
equivalent)=9D if one believes that the Regulatory intended
direction to be indicated must indeed be the current aircraft magnetic
heading and not the current aircraft magnetic course (provided by GPS)
over the surface.
I feel that somewhere in the electronic magic that MEMS
<< https://www.memsnet.org/mems/what_is.html >>
and AHARS
<<
http://www.microstrain.com/inertial/3DM-GX3-25?gclid=CjgKEAjw2dqcBRC2q-
LXjpfxjnQSJAAeYF5LUC4gvWycBVg6DDW_mzzSdTyyF3q0yoQHrT6ij9VbvvD_BwE >>
represents there must be a practical, relatively inexpensive means of
creating a direction indicator that will meet the intended requirements
of 14 CFR 91.205 (d) (9). If so, I (and probably many others) would
like to buy one for my EAB airplane.
How about it experts (and entrepreneurs) are my desires hopeless and
unrealistic?
OC
'O C' Baker says "The best investment you can make is the effort to
gather and understand information."
Message 3
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Subject: | Re Direction Indicator Needs |
MGL also makes 2-1/4" and a 3-1/8" round-hole-mount displays for their
AHRS and compass modules. It's about $1300 for attitude, TC and DG, or
$500 for direction only, including the sensors.
It would be up to you to be certain that these are equivalent to
gyroscopic instruments. The sensors don't contain spinning masses but
sense acceleration and attitude with multiple single-axis vibrating
structures instead. The basic sensors are quite cheap; you can get a "10
degree of freedom" sensor module on a pc board for under $12 which
includes 3 axes each of attitude, acceleration and magnetic field plus a
barometric pressure sensor. Computations that used to take 30 pounds of
synchros can now be done with a Kalman filter running on a fifty cent
microcontroller chip.
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