Category Archives: Wiring

Time: 4 Hours

One nice feature of the VP-X is the flap control. With a position sensor, a smal device the translates the actual position of the flaps into a digital signal, you can take advantage of several features. The first is exact control of the flap motor either up or down with a single switch movement. The second is intermediate flap steps. Once the sensor is set up you can define the value of the flaps full up and flaps full extended. With those two numbers you can use any value in between to have intermediate flap stops. First up is to instal a sensor, I’m using a Ray Allen POS-12 that I got from Aircraft Spruce. There are no plans for how to attach this sensor but a few builders have documented how they did their install. The sensor is just a small potentiometer that has a rod that slides in and out for a total travel of 1.2 inches. The idea is to attach this sensor to the side bulkhead below the flap motor. Then attach the rod end to the flap push tune so that when the rod moves up and down as the flaps do it would either extend or retract the sensor rod. I went to a local hobby shop to get a few parts, clevis’s and threaded rod, that I used to bridge the sensor to the adel clamp I put on the flap push tube. I mounted the sensor to a scrap piece of sheet and put in an approximate 30° bend in the top end to give the sensor a straight shot to the flap tube when I clamped it to the bulkhead. 

It ended up working really well after I made a few adjustments. The idea was to have the sensor rod extend almost completely and retract almost completely. Once I had that adjusted I drilled the bulkhead for a screw to attach it. I hooked up my laptop to the VP-X and brought up the flap settings. The sensor was showing up perfect and just indicates a number between 0-255. That’s the digital number of where the flaps are. The up position was showing 0 so I set the VP-X at 1 to allow the motor to shut off. The number with the flaps full down was 233 so I set that for the flaps full setting. So now when I click the flap switch down on my grip the flaps run to full down and then the motor stops. The same happens with a single click up which brings the flaps full up. The VP-X also allows for two intermediat flap stops. So with the flaps full up or 0° I used my digital level to zero out for 0°. I adjusted the flaps down till the level read 10° down and looked at the sensor number. I plugged that number into the first flap stop. I repeated this process for 20° down flaps for the second flap stop. So now the VP-X goes to 10° flaps with the first click down on the flap switch. Click it again and you get 20° and once more for full flaps down at 40°. One click up and the they retract fully. I will be able to use the sensor data to create a flap indication on the Dynon screen as well later down the road. Turned out to. E a cool feature of the VP-X for just a little extra work. 

Time: 6 Hours

The other day I recieved a box of goodies from Aircraft Spruce that contained several items including the Vertical Power VP-X Pro, Dynon COM and Dynon Intercom. The VP-X is a solid state circuit breaker technology that allows for a lot of customization and control of your electrical system. The pro version is a two buss system for redundancy and safety. I went agead and bought these items so I could power up the plane to check my wiring. I got the COM and intercom so that I could check my intercom harness and the headset jack for squeals and interference. First up was to mount the VP-X and get it into position.  

   Once I got it’s perfect placement I removed it and the brackets it came with to drill four holes for the screws that I would use to attach it. I then returned the VP-X to the spot and clamped it into position so that I could match drill the holes.  
 The forward side of the box I used the shelf I built and screwed it directly to the VP-X instead of the supplied bracket. After all the holes were drilled I removed the front bracket and primed it as well as put in two nutplates.  

 To get power from the battery to the VP-C I needed to run a #4 cable from the battery contactor to the VP-X. I figured out the best run path and needed to drill a hole in a flange just aft of the battery compartment which was just above the battery contactor giving me a straight path to the lug I need to attach to. I had to remove the contactor to get access for the drill.  I also was drilling blind up through the flange and used a mirror to align the drill bit with a mark I made in the center of the flange. I then stepped up the hole size to a 1″ hole for a grommet that allow the cable and terminal to fit through. 

   I then made up the cable for the right length and attached the terminals. With it built I put it into two adel clamps to hold it into place and attached both ends to the VP-X and the contactor. Holding my breath I flipped on the battery master switch and watched as the VP-X lights came on! First test complete – pass. From there I grabbed my laptop I just bought off eBay, it’s a PC and I’m a MacBook guy, since the software is windows based. The VP-X comes with a crossover cable to allow you to transfer information from their configurator  application to the VP-X. The cool thing is the online planner that I designed my electrical system on the Verticalpower.com website creates a file you can use to upload to the VP-X. So that’s what I did and in a few seconds my system was loaded with all my switch inputs and all the avionics I loaded. So when I flipped the boost pumps switch on my pump actuall came on! Test two complete – pass! Now I grabbed my COM unit and intercom and screwed them into the panel for testing. The COM unit is just a head and has a box that I placed in the tail to conect the antanae and power harness up to. With all the harness’s and antanae connected I flipped the avionics switch on….they powered up!  Test three – pass! 

 The knobs and switches all worked and looked great. Now Glenn grabbed his headset and we plugged it in. Glenn turned on his handheld radio and I pulled the PTT switch and whoa it worked and worked very well! No squeals or static, at least not right now. So this proved that all my wiring for the intercom was a success and had no issues with all the grounds I had to deal with in that one harness. I tested both the pilot and passenger headset jacks and changed the com to both the number one spot and number two spot to check both sides wiring. The other thing I was able to test was the flap switch on the pilot grip. I found that I had the two wires backwards and the up went down and the down went up. That was an easy fix with the harness that went to the VP-X. One thing that I didn’t like was that the flap switch had to be held either up or down to make the flaps run continuously. In order to get the full benefits of the VP-X flap control you need to have a flap position sensor installed to allow the system to know where the flaps are at all times. So that’s the next install for me. 

Time: 12 Hours

This blog post is for several days of work since it is mostly about wiring.  After the last post on the start of the VP-X power connectors I finished up the remaining two connectors with all their power wires.  I started by cutting and crimping all the pins in place.   

 I was getting a good rhythm on prepping the wires and crimping before too long.  The tool that they loan out works really well and I had the remaining plugs done pretty quick.

   So that finished up the power connectors so I packaged up the crimper and ran it to the post office to ship back to Vertical Power, thanks Chad Jensen for the great customer service.  After getting that done I moved on to the Dynon harnesses.  I will have to build one for the autopilot panel, intercom and both com units. I started with the autopilot panel and orginized the wires, labeled, cut and crimped the d-sub pins on.   
    
 I followed this up with inserting the pins into the housing and put the d-sub backshell in place.  I repeated these steps for each of the com units and finished their harnesses.  

    
 I decided to skip the intercom for the moment and moved on to the ADSB and transponder.  Both of these have a power wire, and ground wire and two data wires that are orange and purple.  These data wires are what the system uses to transmit and receive data.  The Skyview screens have a 37 pin harness which has 5 sets of data transfer wires.  Each is a different color with a matching purple and orange stripe.  So you pick a color or port and match the orange wire from the equipment like the transponder to the colored wire that has the orange stripe and repeat with the purple.  I used port #1 for the VP-X so that it can communicate with the Skyview system giving all kinds of information like how tha battery is doing and other electrical draws.  Port #2 was used for the transponder and port #3 for the ADSB.  Since I’m having dual screen, a 10″ and a 7″ I have to split the wires from the items, transponder, ADSB etc., to both screens so that they both receive the information.  I hung the two 37pin harnesses on the back wall of the avionics area so that the length of the wires would be at a good distance to make the harness reach the screens.  

    
 Since I started with port #1 I finished up the last d-sub connector for the VP-X which houses the data wires as well. 

 So on to the intercom, the worst one.  So for the record I am not a avionics guy and have no training on this stuff, with that said this is the hardest harness for me to build and this is why.  From reading all about avionics specifically the communications parts the biggest problem is for noises to come through your headset like buzzing or static.  To prevent these noises you use shielded wire, or wires that are encased with a braided cover under the white tefzel coating.  This braided shield is to prevent other electronics like servos or motors from introducing noise into the communication wires.  Makes sense to me that having these shields is a good thing.  Here is the second thing that you have to do to prevent that noise introduction, grounding.  So this shield needs to be grounded or connected to the airframe so that electrical charges can be dissipated.  The biggest cause of noises in the system come from ground looping.  Something new to me but the idea is that if you ground each end of a wire run there is the possibility that there is a different charge on each end of the shielding and could create a bad situation.  So you leave one end ungrounded and ground the opposite one.  Dynon wants you to have the ground come into the intercom and then to the ground block.  So here is the fun part, I have 8 shielded wire bundles that need to be grounded.  On top of that there are 6 of the wires that are inside those eight bundles that need to be grounded too.  So what I have is 8 shields, 6 internal wires, a wire that will go to the pin in the d-sub and a wire that will go to the ground block that need to be connected together.  This basically brings all grounds to one point and prevents any chance of ground looping.  With all this chaos I had to really plan out my attack on them and figure what I wanted to do.   

 Here is what the block view of the d-sub looks like from the manual.  You can see my chicken scratch on it helping me to understand what I was doing.  

 I used solder sleeves, like I have in the past, to terminate the shielding.  I used one wire to figure out the best length for the harness and cut the wire.  I then measured back 3″ to and removed that covering, trimmed the shielding and connected the solder sleeve.  

    
 So now I had the 8 shields terminated and a lead off of them.  My plans was to solder these together and fold them back over so that a single wire could be added going towards the d-sub and a single wire back to the ground block.  I also needed to add the 6 internal wires to tie into this bundle. I zip tied the ends together to hold them in place so I could solder.  

   I didn’t think that my solder iron would heat up this large bundle so I used my small torch to heat the wires and solder them.  
 I added the wire that will go to the d-sub pin, each time I added wires I used a strand of wire to wrap around the bundle to hold them in place and just soldered over it.   

 Now that I had all the shield wires, the ground wire and the pin wire soldered I needed to add the 6 wires from inside the shielded wires.  These wires are directed towards the d-sub connector so they needed to be bent back to be able to connect to the soldered part, and I didn’t forget the heat shrink before soldering them.  

    
 So now I had all 23 wires completed with their pins installed and needed to insert them into the d-sub housing.  Before doing that I slid a large piece of heat shrink over all the wires to finish them off when done.   

   I then spent some time straightening out the wires so they looked good and zip tied the harness and added the backshelll.

   
 So that was a very tough harness to make and took a lot of thought and planning.  I’m real happy with how it turned out and think that it will work just fine.  I would say I’m probably 85% done with my wiring which makes me happy thinking that all I need to do is screw in the avionics and connect these harnesses and I will be good to go, keeping my fingers crossed as I say that.  I few more items left for me to then I’m off to connecting the wings to the fuselage which is a really cool thought.

Time: 4 Hours

I recieved the loaner crimpers from Chad at Verticle Power this weekend. So I decided to start the work for the power connectors so that I could get them back to him as soon as possible. These crimpers have a slot for the pins to slide into to hold it into perfect position. Once in position there is a sliding do-hicky that come down from the top to limit the wire that’s being inserted from going in to far.  

 Here is what the pins look like out and inserted into the crimpers.  

   
    Here’s the wire stop do-hicky lowered. 
 So with the basics down, Vertical Power has a pretty good instruction manual, I started with the J8 power connector. There are three connectors that use this type of pin, J8 (8 pins), J10 (10 pins) and J12 ( yep 12 pins). The process is fairly straight forward as long as you follow their instructions. After crimping the insertion is done by aligning a little tab on the back of the pin to a notch next to the hole you are inserting it in. This is different from the other Molex connectors I have done which don’t require alignment during insertion. I figured out a good final length that I wanted for the harness. One that made sure I could reach the VP-X as well as giving me plenty of slack to install and move things around. Keeping my fingers crossed that when the day comes to install the VP-X I will have measured correctly.  

    
   Once I had all 8 pins done I cleaned up all the wires and zip tied them to create a nice harness.  

    
 It definitely helps to clean up all the wires in this side of the space. Now off to the other two connectors.