Gauges

ADS-B in for $20

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ADS-B ( Automatic Dependant Surveillance Broadcast ) provides much needed information to pilots and air traffic controllers. ATC can see the location, speed and direction of any aircraft equipped with ADS-B out. Pilots can see other aircraft with ADS-B out and get updated information such as weather and temporary flight restrictions. Historically getting access to this data required expensive avionics but recently a few low cost solutions have appeared.

With some specialized software European USB TV tuners can pickup the ADS-B signals and thanks to mass production such devices can be purchased for under $20. I purchased a tuner that comes with an external antenna from Amazon.

NooElec SDR
NooElec SDR

Using a USB OTG cable I connected the tuner to my tablet.

USB OTG with charge cable
USB OTG with charge cable

I already had Avare installed and setup so I only needed to install ADSB Receiver Pro on my tablet. Now when using Avare I can see other aircraft and weather data.

Blue dots represent other aircraft
Blue dots represent other aircraft

If you need more detailed directions to get this setup head over to the site that made this possible: http://hiz.ch/index.php/home/adsb-receiver

The FAA has mandated that aircraft flying in nearly all controlled airspace must be equipped​ with ADS-B out by Jan 1st 2020. I hope this mandate helps drive some competition in the market and bring down prices of ADS-B out transponders. In the meantime at least I can pickup ADS-B in with little investment.

Wiring Engine Information System

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The EIS monitors the cylinder head temp, exhaust gas temp, RPM, battery voltage and air temperature. Each item can have limits set so if something is out of the ordinary the warning light on the dash will illuminate.

The cylinder head temperature probes sit between the sparkplugs and head. I ran the wires through the fins and up the side of the engine where they are held in place with a clamp. The exhaust gas temperature probe wire is also held by this same clip.

Cylinder head temperature probe wires run through fins
Cylinder head temperature probe wires run through fins
EGT and CGT probe wire secured with wire clamp
EGT and CGT probe wire secured with wire clamp

The probe wire then run to the front of the engine where another wire clamp was added.

EGT and CHT wires routed over starter
EGT and CHT wires routed over starter

The EIS harness terminates in from of the battery where the probes are connected. I kept the pair of wires for the second exhaust gas probe in the harness even tho I’m not using them. Maybe some day this airplane is updated to two cylinder and then they are needed.

EGT and CGT connected to EIS harness
EGT and CGT connected to EIS harness

The grey  tachometer wire goes to the other side of the engine and connects to the lighting coil. I spliced an extra connector into the voltage regulator wires to connect the tach input. Still need to put an end on the grey tach wire.

Lighting coil & tach connection
Lighting coil & tach connection

The EIS uses a single DB-25 connector for all the wires. I took the connector apart and removed all of the unused wires by pushing the pins out with needle nose pliers. A few of the wires exit the EIS harness just behind the connector such as power, ground, fuel sender and warning light.

EIS connector
EIS connector

The violet wire runs through the harness to the warning light with the other side of the warning light is connected to power. I made sure that the dash is easily removed by disconnecting wires as opposed to having to cut wires to remove it.

EIS warning light
EIS warning light

The last item to connect is the green wire to the fuel level sending units from the gas tanks. When it gets a little warmer I’ll roll her outside, mount the wings and tanks and then work on routing the fuel sensor wires. I’m not exactly sure where everything ends up so not much I can do with that for now.

Fuel Gauge

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Started working on the electrical wiring and discovered that the EIS 2000 I have only supports a single fuel level input. They sell the EIS 2000 as a two or four stroke model when in reality it does not matter if you have a two or four stroke the difference between the two models is features not engine type. When I build the next airplane I think I will build my own EIS or use the flybox.

So the Grand Rapids folks suggested using a switch so I can select what tank level I want to monitor. After thinking about this for some time I decided this is the best option but that it needs to be implemented carefully. Imagine monitoring the full tank but running the engine from the empty tank. That could result in a bad day. 

In designing this I decided the goals should be as follows: 

  1. The position of the tank selector valve dictates what fuel tank is monitored by the EIS
  2. If the fuel selector valve is in the off position then the EIS should see an empty tank triggering the warning 

The typical inexpensive fuel selector valve is not suitable for triggering some electrical switches. I ended up purchasing a WSM 006-600 jet ski fuel valve on Amazon.com and a couple of 2750017 micro switches from the local RadioShack. 

Fuel valve and micro switches
Fuel valve and micro switches

Using a file I put a flat spot on the knob that was parallel to the flat side of the D hole in the knob. The location of the flat spot is important so if you have a different valve you might need to change the location.

Fuel valve knob modified with notch
Fuel valve knob modified with notch

When the knob is installed on the valve the flat spot should line up with a micro switch roller only when the valve is turned to the left or right tank. This will require the switches to be mounted 180° from one another. I used OnShape.com to make a drawing that I printed out in reverse on toner transfer paper. This will provide accurate centers for the holes and the labels for the valve. 

Putting the switches to their marked locations on the toner transfer paper you can get an idea of how this will work. 

Arrangement of micro switches
Arrangement of micro switches

I varnished a piece of plywood, sanded it smooth and applied the toner transfer. Then the parts were cut out and drilled. A smaller valve support plate needs to be 5/8″ away from the panel so the notch in the knob is just below the plywood. 

Micro switch actuated by notch
Micro switch actuated by notch

On the outside, for asthetics I used 1/4″ X 3/4″ pine. A 1/8″ notch was cut into the outside piece and the valve support set into the notch. The inboard side used a small piece of 1/4″ X 5/8″ pine. Alignment is important so I glued this together with the valve and knob installed to keep everything indexed.

Fuel valve support
Fuel valve support

Once the epoxy cured the switches were mounted using #3 screws and the valve installed. 

Fuel valve, switches and wiring
Fuel valve, switches and wiring
Fuel selector knob and labeled panel
Fuel selector knob and labeled panel

The electrical wiring did take a little bit of planning. I wanted to make sure that should there ever be a malfunction that only a single fuel level sensor would be connected to the EIS. Here is the wiring diagram that does this: 
http://schematics.com/embed/fuel-sender-selector-46440/full

Before takeoff simply turning the valve to all three positions will confirm if the system is functioning properly.

I think this turned out well, looks pretty good mounted on the fuselage side. 

Fuel tank selector valve
Fuel tank selector valve

Toner Transfer

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I’m still not happy with the dash so time for the fourth iteration. This time I designed it in CAD using OnShape.com, including all of the labels. To fabricate it and apply labels I thought using a tuner transfer method might be nice.

First the wood was vanished and sanded smooth. I only had A4 size toner transfer paper so I had to print multiple pages to cover the whole dash. PosteRazor was very helpful in printing the pages, just don’t forget to mirror your CAD image before printing.

Starting with the center bottom page I taped it to the board and used the wife’s iron to transfer the toner. To align the next page I pushed T-pins into various reference points.

Pins to mark index locations
Pins to mark index locations

Those same reference points were poked through the paper.

Pins to mark index locations
Pins to mark index locations

Then using the holes the next page was aligned using multiple reference points.

Aligning the transfer paper
Aligning the transfer paper

Then the page was tapped in place and toner transferred with the iron. This process was repeated until the whole dash was completed. The nice thing is if you mess up just sand off the mistake and try again!

Since all the holes were marked with toner it was really easy to cut out all of the holes precisely where I wanted then.

Toner transfer also marked hole locations
Toner transfer also marked hole locations

I might want to add some more text or switches before I complete the airplane so for now I am leaving off the final coat of varnish. But once completed I plan to add a couple of coats to help protect the toner from abrasion.

Preview of final dash
Preview of final dash

I recently started working on the electrical wiring and quickly discovered that most 12v USB phone chargers emit RF interference like crazy. When tuned to around 132Mhz the interference makes reception impossible. Anyone know of a decent priced charger that does not emit tons of RF?

Dashboard Take Three

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Lurking on ETLB forum I stumbled across a post from Brian about his V-Max dash that had some rubber insulators between the fuselage and the dash. Makes sense to me, reducing the amount of engine vibration that reaches the gauges is a good thing. So I decided to do the same thing.  Ordered some rubber vibration isolation mounts.

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Vibration isolators

These isolators have M5 threads and are about 5/8″ in diameter. The rubber section is also about 5/8″ high.

Next I created three triangular brackets using some RS-1 and 1/8″ plywood. 

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Dashboard Bracket

The dash panel is attached to the brackets using two bolts. By using bolts I can easily replace the dash panel in the future should I ever install different gauges.

The most important thing to remember is that the dash panel and anything attached to it must not touch any part of the airplane. Any wiring or tubing that is attached must be loose and free otherwise it will transmit vibrations to the dash.

Because of that I mounted the trim adjuster to the fuselage using an aluminum bracket, this way vibrations are not transmitted to the dash through the stiff cable.

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Pitch trim adjuster bracket

Since the dash is angled I made a shim so the adjuster can be mounted at the same angle.

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Pitch trim shim

The notch is to clear the front spar carry through bolt.

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Pitch trim adjuster

The hole is the dash is made about 1/4″ diameter larger than the adjuster knob so it does not touch the dash.

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Clearance for pitch trim

Mounting the dash this way will make it easier to inspect and maintain these components.

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Rear of dash panel

On the right side the bolts holding the EIS in place are also used to attach the dash panel to the bracket.

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The final result looks great.

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Completed dash

Now I just need to take it all apart so I can varnish the panel and brackets.

Mounting the Radio

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After sitting in the cockpit trying different locations I decided to mount the radio on the dash. I had to make a small spacer of 1/8″ ply because the back of the radio is recessed where the screws are located.

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Spacer for radio
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Back of radio

It fits well in this location with the modified Yaesu adapter I made.

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Radio mounted

This location did block one of the two switches I had on the dash and the one unblocked switch cannot have a cover because the radio adapter keeps the cover from opening. I plan to enlarge the blocked switch hole to feed the radio wires through the dash. I’m undecided on what I want to do about switches. I really only need one switch but if my generator fails it would be nice to be able to turn off non-essentials to preserve battery power.

At this time I will go with just one switch next to the starter key. The dash is looking really nice so far.

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MiniMax dash with radio mounted

Static Ports

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Before covering the tail section of the fuselage I thought it would be a good idea to build some static ports and run the tubing. The flight manual says to put the static ports in the center of the diagonal between stations six and seven.

I cut a 3/4″ cube from some scrap wood and drilled a 19/64″ hole through the center. Then used a 11/32 to drill nearly all the way through leaving about 1/8″ of the 19/64″ hole.

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Static port block

I then put some CA ( super glue ) on the 19/64″ portion of the hole. Once dry I run a 1/8-27 NPT tap through the hole. As the tap cut I would remove it, add more CA, let it dry and then tap a little deeper. The end result is some nice strong threads in the block.

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Static port block with threads

Next I cut a 1 1/2″ square piece of 1/8″ plywood and drilled a 19/64″ hole in the center.

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Static port base

Next I used the 19/64″ drill bit to line up the block and plywood to glue them together.

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Now the hose adapter can be installed so you can get an idea of the final result.

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Static port assembly
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Static port assembly

The plug on the outside is some fastener I found at the local hardware store. To make them useful I drilled a 1/16″ hole in the center.

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1/16" hole for static port

I glued the assembly in the center of the diagonal between stations six and seven.

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Attached static port to fuselage

Once the glue was set I vanished the exposed wood then started running the tubing. I put a tee between the two ports.

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Static port tee and tubing

Drilled a hole in the elevator cable bracket on station six to hold the tubing.

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Tubing support

Did the same at station five and a hole was drilled in station four directly under the left rudder cable.

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Tubing support

Another hole was drilled in the seat support directly above the elevator trim cable.

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The tube follows the same path as the trim cable up behind the instruments. I did not connect it to the instruments yet because I have not decided on the exact routing behind the dash so no pictures of that. The plan is to add tee so it can be connected to the air speed indicator and altimeter.

Updated Dashboard

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My first dash was made from 1/4″ plywood, this was difficult to deal with since most panel mount items are made for a maximum of 1/8″ panels. The problem with 1/8″ panels is they are too flimsy and need additional support. I’ll worry about that a bit later. I started with the same type of plywood used on the fuselage sides, thought the matching color would look nice. After drilling, sanding and varnish I have a nice looking dash.

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Minimax dashboard

The tablet will mount to the four holes in the center. The next problem is making the dashboard stiffer. The first thing I did was cut the perimeter of the original 1/4″ dash.

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The bottom needed to be cut down to 1/8″

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Next I created two support members and glued the three pieces in place.

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I also added a piece of 1/8″ ply to the center mount point.

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The trim adjuster was also bolted to the support brace.

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The result is a rigid dashboard that can easily be replaced should I decide to rearrange/replace the instruments in the future. It also looks really nice.

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Compass

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Since electronics can fail when you need them most, mechanical backups can be a life saver.

I did not want to put a compass in the dash since that would place it closer to electronics that will interfere with the compass. Found this pedestal mount compass that will be easy to mount to the canopy deck.

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Pedestal compass

It did require a couple washers between canopy and compass on the right and left screws to account for the curve of the canopy. With the compass installed the dash is looking nice.

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Compass installed

Instruments and Switches

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With the fuselage nearly completed I started working on the gauges and electrical system. Using some 1/4″ plywood I started laying out the dash.

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Once everything was in place the dash was cut out. Three corner blocks were made and bolted to the dash board using threaded inserts. Wax paper separated the blocks from the board to ensure only the blocks get glued.

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After a little bit of sanding to get the dash sitting at the correct angle the blocks were glued to the fuselage.

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Empty dash

Since the dash is not glued in place I can easily removed it and  replace it should I ever decide to modify the layout. Mounting the components was much easier with it removed so the three bolts were removed.

The toggle switches were not long enough to fit through the 1/4″ plywood so I used the router on the back side to remove some material in that area.

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Cutout for switches

All of the switches were mounted.

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Switch connectors
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Toggle switch covers

The two red ones will control the redundant magnetos. This allows me to turn each off, one at a time, to ensure each ignition system is working before flight. To stop the engine both switches will must be flipped at the same time. The blue ones will control items like the radio, auxiliary power etc.

The next component to install is the engine information system (EIS).

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Engine information system

This monitors engine temperature, fuel level and various other important things. If it detects a problem it will alert the pilot by activating the warning light.

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Warning light

Next I installed some USB charge ports and a cigarette lighter port. This should be sufficient to power any accessories.

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Power for accessories

The keyed switch needs a small block glued to the back of the dash to keep the switch body from rotating.

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Block to help support ignition switch

This switch controls the master power and engine starter.

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Keyed ignition switch

Last are the two most important gauges. The air speed indicator. The airplane needs about 28MPH just to fly and is designed for a top speed of 90MPH. Flying too slow or fast could be fatal.

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Falcon air speed indicator

The altimeter simply tells us how high, above sea level, we are. Airspace restrictions can vary by altitude plus there might be mountains or towers requiring an altitude change.

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UMA non-sensitive altimeter

The dash was bolted to the fuselage to check the fit. Hooking up wires and tubes will be rasy with the cockpit opened.

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Back side of dash

It looks good with the cockpit closed.

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Dash with canopy closed

I will also have a compass but it’s currently on a UPS truck somewhere. When it arrives I plan to mount it on top of the canopy deck in the center.