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Old 11-09-2017, 12:18 AM
svyolo svyolo is offline
Join Date: Oct 2017
Location: bellingham, wa
Posts: 202

Skipping the FPM, is skipping the best part of the HUD. It even gives you a really accurate, smooth AOA, without any air instruments. The difference between where the airplane is pointed, and where the FPM is, is your AOA, if you are straight and level.

I think I would used airline style scales for airspeed and altitude, vs the Vipers.
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Old 11-09-2017, 12:03 PM
sblack sblack is offline
Join Date: Dec 2009
Location: Montreal
Posts: 1,499

I was excited by the GRT system, but there just isn't room to install it on an RV4 canopy.
Scott Black
Old school simple VFR RV 4, O-320, wood prop, MGL iEfis Lite
VAF dues 2020
Instagram @sblack2154
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Old 01-03-2019, 01:59 AM
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hpmicrowave hpmicrowave is offline
Join Date: Nov 2007
Location: Fort Walton Beach, FL
Posts: 101
Default MGL - Dynon DIY HUD Development Project

Along with many other pilots I?ve always wanted a HUD in my plane and have explored many possibilities through the years. After reading the previously mentioned kitplanes Magazine Article on HUD's in experimental aircraft and how Grand Rapids Avionics is integrating a generic HUD with their EFIS I bought a similar HUD sold as a car HUD that will accept an HDMI video input and a small group of us have started our own experimental avionics HUD project. I?m convinced now having my own HUD is very close to happening.
The big thing here is I have a HUD projector that can be seen in daylight (14,000 nits), it?s not overly bright but it works in sunlight, it has good enough resolution (480x240), and is full color (not all colors work well on HUDs in daylight but the ones that do are there). I first tested the HUD using the straight VGA Video Out from both the MGL Odyssey and MGL iEFIS Explorer through their VGA output port and then into a VGA to HDMI converter and then into the HUD projector. At first only the VGA video from the Odyssey worked correctly but recent iEfis VGA SW updates have made it compatible also. But to optimize using the straight VGA Video out from the iEFIS requires a user MGL screen design that keeps as much Black background as possible with critical HUD data superimposed on this black background like you would want from a HUD, this worked but it makes your panel screen and the HUD both into HUD screens, not what you really want.

So we now have a small project team using a Raspberry PI microcomputer to read and process the MGL serial Blackbox data stream and then output this as a HUD formatted HDMI video signal into the HUD projector to create a custom HUD display designed for MGL Efis users (Odyssey and iEFIS). Since were community here on VANS forum were also writing our SW to be Dynon serial data compatible (MGL or Dynon data is selected in the configuration file read at startup).

The HUD?s were using so far for development are pretty cheap (around $300) and take a direct digital HDMI signal that appears to be good enough for experimental aircraft usage. The HUD can also display iPhone and Android phone video out (not of interest to us right now).
The Raspberry PI microcomputer costs about $26 to $35 and has a built in HDMI interface. Were writing the SW in the Python programming language on the PI. So far we can process and display on the HUD real-time attitude, airspeed, altitude, GndSpeed, Mag Heading, Gnd Track, and the Alt Baro Setting. Much additional data is being read but not yet displayed. Development continues at our part time pace. Were kind of using the F18/HUD display as base line for this early SW development. Were shooting to have 4 selectable HUD displays 1-Nav, 2-Appch, 3-Maneuvering, 4-Special Purpose (let your mind fill in what this could be). When completed the SW should be available for all MGL and Dynon users and will hopefully setup through its configuration file. It doesn?t send data to or try to control your EFIS so it will be a passive addition to your avionics.

Any serious Raspberry Pi developers who might be interested in joining our little GitHub group send me a PM. Some development pics are available on the MGL forum.

Kitplanes HUD Magazine article:

MGL Black Box Serial Data Feed Details (data available for HUD display).

Check the Dynon and Skyview pilot manuals for the EFIS SERIAL DATA OUTPUT Format (available real-time data) for their RS232 port.
Cecil "TRON"
RV8 N95CH In Phase 1 !!
RV6A Flying with Son Chris
Member, FlyOnSpeed Team
Sling 4 TSI Tail Done, Fuselage next
2021 Dues Paid, Home Field 18FD

Last edited by hpmicrowave : 01-03-2019 at 09:24 AM.
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Old 01-03-2019, 09:29 AM
Canadian_JOY Canadian_JOY is offline
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,388

Cecil - this sounds like a very exciting project.

I'm curious... so far some reviewers of the GRT solution grouse about the car HUD devices not being focused at infinity. Is this an aspect you are hoping to overcome with your development, or one of those things one has to make peace with in order to have an affordable HUD?

I have GRT avionics in our aircraft and would love to have a HUD. So far I'm not enamored with the GRT solution as the car HUD devices seem a bit "kludgey". Too many wires and adapters required to make everything run. I am liking GRT's idea of using a dedicated microcomputer (compute stick) to do the massaging of data from the EFIS.

One important feature for me is the ability to have the HUD image inverted so the projector can be mounted below the HUD combiner glass. I suspect this is a pretty simple software switch, but I don't write software code so may be out to lunch. Nevertheless, it's a feature which is pretty much mandatory if considering applications outside the world of RV's.
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Old 01-03-2019, 09:48 AM
andrewtac andrewtac is offline
Join Date: May 2014
Location: Friendswood TX
Posts: 315

Interested, sent a pm
Mark Andrew Tacquard

RV8 N189DK
RV10 in progress
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Old 01-03-2019, 11:30 AM
Pdtofly Pdtofly is offline
Join Date: Jan 2012
Location: Reno, NV
Posts: 492
Default Me to


I am interested also. PM sent.

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Old 01-03-2019, 11:35 AM
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hpmicrowave hpmicrowave is offline
Join Date: Nov 2007
Location: Fort Walton Beach, FL
Posts: 101
Default DIY HUD

The key to our project is that we are developing an open source HUD SW processor with an HDMI video output so it should be able to feed any HUD system with a HDMI input. One of our team does want the video flipped for an on the glare shield mount so that option will be in the cofiguration set up file.

Yes most car HUDs are not set up for an infinity projection, but my test unit (same as the GRT unit) in my bench out the window tests looks to be focused about at the prop and I think it’s acceptable.

The Epic Optix HUD I believe will take an HDMI video input (I’m checking now) and it’s focused at infinity so that commercial unit made directly for aviation would provide a more perfect projection, at a higher cost (about $1700 right now).

The MyGoFlight HUD unit appears from the pictures I’ve seen to use the same projection unit as the GRT HUDLY unit (their documentation doesn’t say its projected to infinity?) and their working toward an FAA certification (approx $20k installed?) so near infinity may be good enough for the FAA.
Cecil "TRON"
RV8 N95CH In Phase 1 !!
RV6A Flying with Son Chris
Member, FlyOnSpeed Team
Sling 4 TSI Tail Done, Fuselage next
2021 Dues Paid, Home Field 18FD

Last edited by hpmicrowave : 01-03-2019 at 12:52 PM.
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Old 01-04-2019, 02:45 PM
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Brantel Brantel is offline
Join Date: Mar 2006
Location: Newport, TN
Posts: 7,509

If these guys will have me, I hope to add Garmin?s serial stream to the mix of selectable protocols the HUD processor can support.
Brantel (Brian Chesteen),
Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
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Old 01-04-2019, 03:42 PM
Canadian_JOY Canadian_JOY is offline
Join Date: Aug 2007
Location: Ontario, Canada
Posts: 2,388

Thanks for the clear, concise reply to my questions, Cecil. This sounds like an excellent project indeed! I'm a software dolt so I won't be volunteering, unless you want a high quality generator of bugs! LoL
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Old 01-04-2019, 09:23 PM
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Snowflake Snowflake is offline
Join Date: Oct 2009
Location: Sidney, BC, Canada
Posts: 4,111

FWIW, I have one of the new Hudly units gathering dust on my shelf. I really like the performance of it in the car, in daylight. Extremely readable, and even though it's not focused at infinity it feels seamless to glance at it.

I stopped using it in the car after about a week though, because the WiFi connection between my phone and the Hudly won't stay connected. Hudly says this isn't a problem with the Hudly, and they are "sort of" right. My phone is set to use WiFi when available to save on data charges, and doing so means it'll hop from known WiFi to known WiFi to find a signal that has internet access. We have city-wide WiFi here that has reasonable, but not perfect, coverage... When I drive into an area where I am covered, the phone switches to the local WiFi, and drops the Hudly connection. Not very useful if you're using the Hudly for driving directions.

Hudly's solution is to turn off WiFi roaming. Not a solution for me, sorry.

However, the Hudly unit itself would work well in the airplane if I had something to supply data to it. This talk of using a Raspberry Pi makes me wonder if we should be combining efforts with the Stratux team. My Stratux has GPS, AHRS, pressure ALT, and traffic and weather via ADS-B. And the Pi has HDMI out. Surely we could leverage all of that and have a combined device that gives useful heads-up info on the Hudly (wired via HDMI) without losing the traffic info already served over WiFi to our tablets/phones?
Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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