REFLECTOR: Reflector Digest, Vol 94, Issue 37

[James Lotspeich]

It's been a while, but I believe Cloudcap builds laser altimeters for
precision autopilot landings (UAV autopilot).  The cost six years ago was
~$1k.  Worked pretty well when wings are level up to maybe 1000ft.  With an
IMU or AHRS unit, you can tell when you're level.  The laser will give a
good height above ground.  Both units feed serial data or CAN bus.  I'd
trust the laser over field elevation calculations.  Also could be used for
an auto gear down if you're feeling really experimental.

James

On Wednesday, January 23, 2013, Richard J. Gentil wrote:

> Hi Dave,
>
> I'm sorry I didn't make myself clear. I was going on the premise of
> building your own because the topic had mentioned building a single PCB
> computer to do what you needed. My comment was on how Avidyne handled it
> with the information from the Garmin and it was something that if you were
> thinking of designing on your own could give you some ideas on how to
> implement it. And I should add if you did build it, I would be happy to
> take one off your hands. ;)
>
> Richard
>
> Sent from my iPhone 5
>
> On Jan 23, 2013, at 2:43 PM, Dave T Nelson <dtnelson at us.ibm.com> wrote:
>
> *I'll respond to Rich Ervin and Rich Gentil below...*
>
> *From:*
> ----- Message from Rich Ervin <rich_ervin at hotmail.com> on Wed, 23 Jan
> 2013 13:54:25 -0500 -----
> *To:*
>
>    <reflector at tvbf.org>
>
>  *Subject:*
>
>    Re: REFLECTOR: Need a topic... gear down check
>
>  Any way to build this based on altitude or distance to ground? Some
> simple range detecting device that can measure the distance to the ground?
>
> *What I'm planning is to use the Dynon altitude (referenced to MSL), and
> subtract the altitude of the destination airport (using the three letter
> identifier and a quick database look up)... to approximate the AGL
> altitude.  This is far from perfect... I've looked at trying to find an
> elevation database I could use and reference via lat/long... but so far no
> luck. *
>
> *From*:
> ----- Message from "Richard J. Gentil" <richard at naples-air-center.com> on
> Wed, 23 Jan 2013 14:22:12 -0500 -----
> *To:*
>
>    Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>
>  *Subject:*
>
>    Re: REFLECTOR: Need a topic... gear down check
>
>  Rich,
>
> You could use a radar altimeter. Also the Avidyne System in the Cirrus
> uses the GPS to give you TAWS terrain warnings when you are more then 5
> miles from an airport and it calls out 500ft when you are on approach
> before landing at an airport.
>
> I would think that something like that would be what you are looking for
> in order to integrate with a gear warning if the gear is still up.
>
> Richard
>
> *I've actually looked at homebrew radar altimeters for this
> application... complicated and expensive.  The Avidyne system in a Cirrus
> is quite different from my Garmin GNS-530W... my Garmin has terrain
> warnings, but unfortunately does not output anything usable regarding
> terrain warning or AGL altitude in the RS-232 data string.  As I'm not
> ready to by an Avidyne (or a Cirrus), I'm kinda out of luck on that front
> and working on my own solution.*
>
> *To all - thanks for the input!*
>
>
> Dave
>
> Dave T. Nelson
> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
> Program Director, ISC ECAT NPI & Test Engineering
>
>
>
> ------------------------------
> To: reflector at tvbf.org
> From: dtnelson at us.ibm.com
> Date: Wed, 23 Jan 2013 10:56:02 -0600
>
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