Category Archives: Fuselage

Flap Sensor

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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. 

VP-X and Communications

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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. 

Gear Bolt Mod

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Time: 5 Hours

If you remember in my previous blog posts I did quite a bit of work to the landing gear towers to open them up and make it easier, relatively speaking, to access the landing gear bolt nuts. The boats go up through landing gear into the landing gear tower where the nuts needed to be torqued. This task has proved to be very difficult for many builders as there’s not a whole lot of room in the towers. Not too long ago my buddy Glenn and I read about another builder and some clips he was making and selling. These look very cool to us and thought we would try them! What they are is a couple pieces of strong steal U-channel that is just wide enough that the head of the gear bolt, when turned correctly, fit in between. A hole is drilled to allow the bolt to slide down through and the head be sandwiched between the two flanges of the U shape. Here are a couple photos to better describe what I’m talking about. 

   The theory here is that the bolts would be installed backwards or down through the gear towers and the gear legs versus up through them. This metal clip would then bind against another nut in the tower to prevent it from spinning. What this allows is the nut to be placed on the bottom of the gear legs, easily accessible to torque with just one person as the bolt head would remain stationary due to these clips. 
 After five hours of swearing, removing various nuts, holding back wires that are run and moving brake lines I was able to modify and manipulate these clips along with the bolts to finally get them in their final position! The clips needed some modifications to fit around other nuts that are in the gear tower as the tolerances are pretty close in the space. So you read that correctly five hours to install four bolts! The first picture shows you the normal condition with the nut inside the gear tower and how hard it would be to get a socket and torque wrench in there to adjust these. The second photo shows the mod with the bolts going down through.
   I did buy new gear bolts to adjust for the slight increase in thickness of the clips as well as to address the original bolts that were only showing one maybe one and a half threads. I ordered new bolts from Genuine Aircraft Hardware and adjusted the bolt I ordered. The original bolt was a close tolerance NAS6206-27 bolt. I ordered a NAS6606-27 bolt to replace it. This new bolt has the same grip length just a little longer threaded portion which adds to the overall length of the bolt by about 1/8″. Now I have 2 to 3 threads showing outside of the nut as it is torqued. As for was this modification worth it in the pain in the butt it it was to get these bolts and clips down in the tower? A definitely yes as it took me 10 seconds to torque the nut and I could do it all by myself. These bolts and nuts will need to be torqued every one hundred flight hours and this mod allows me to do that by myself very easily. So a little hardship now will pay off greatly in the long term, I only wish that I had done this mod back when I was assembling the landing gear which would’ve made it so much easier!

Fuel Tank Attach Brackets

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Time: 8 Hours

After finishing the rear spar you have one task to complete before moving on to the fuel tank attached brackets. The fuselage bottom skin overlaps the wing by a few inches. The usual eventually get combined together with screws after the wings are attached for the final time. The wings skins add the holes drilled in them already but the fuselage skin does not. What you were supposed to do is mark all the holes on the wing skin with lines before attaching the wings so that you have a reference point and distance in order to drill the skin on the fuselage. However they make a cool drill jig that my buddy Glenn had so I borrowed it and made quick work of these holes. This tool basically as one side with a nipple that will identify the hole on the wing skin and sandwiches the fuselage skin between the tool so that you can drill the skin and it will match up perfectly. 

    
 I know that’s not the best description hopefully the pictures will help describe it better. So now when I remove the wings I will dimple the fuselage skin and put nutplates in the wing skin. With that tool I was able to get all these holes done really quick. From there you move on to the fuel tank attach brackets. When I built the fuel tanks I had put a bracket on each forward inboard corner that would eventually mate up with the brackets I need to make. The plans call for these brackets to be made out of U channel aluminum.  

 So I took the dimensions and measurements and marked them on the two pieces of U channel. 

    
   After four hours of drilling, cutting, grinding, sanding and filing I had the two final pieces. 
 This is where they will fit eventually.  

   As you can see that they don’t fit completely flush up against the fuselage, and flush against the tank bracket. Van’s says to hit them with the large hammer in a vice to bend them to get them to sit flush at both locations.  That is an understatement! These things are thick and not easily bent. It took me an hour to bend and manipulate the right side to get it to fit flush against the fuselage and the tank bracket. From there you clamp the brackets together with it tight against the fuselage and drill from inside the fuselage through the bracket. This is not an easy task as it’s pretty tight inside the fuselage. I started with a 12″ #30 drillbit from inside and finished with the  #12 drillbit in my angle drill from the outside. with the first hole drilled I put in AN 3–7 bolt in and tightened it down to hold it tight against the fuselage. I then drilled the second hole and repeated the steps to finish that bracket.  

  

  

 I moved on to the other side and finished it up a little quicker than the first as I had a little insight as to where to bend.  

 With both brackets secured to the fuselage I marked the brackets for the single AN4 bolt and drilled the hole.    

 So now all the wing attach points have been completed. This will no allow me to build and rig things like the aileron attachment, flap rigging and fuel line connections. 

 

Rear Wing Spar

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Time: 4 Hours

Once I had the wings initially attached I set out to make their final adjustments. Even though the wings are securely attached at the main spar they still have a little bit of play since the rear spar is not drilled yet. This allows you to make adjustments before drilling and finalize their position. There are three adjustments that need to be done. First is the sweep forward and aft with regards to the wing tip and fuselage. To measure this you run four plum bobs along the wings. Then you run a taught string along the floor so that all four of the plum bob’s a line on that string. You can make adjustments forward and aft to get them to line up. The plans allow for up to 1/2″ in the difference. My wings were wishing 1/8″ and I tweeted them a little to tighten them up a little more.   

 The second measurement is to make the wings square with the fuselage. To do this you make a measurement from the tip of the leading edge on the vertical stabilizer to the seam on the wing top skins at the wing tip. Again you get a 1/2″ play in the two sides and I had less then a 1/16″. The final and most critical measurement is the angle of incidence. Every wing has some angle of attack built in to it with reference to a level fuselage. Van’s tells you that with a level fuselage you can run a level from the leading edge of the main spar flange to the aft edge of the rear spar flange and there should be exactly 2 51/64″ space between the aft end of the level and the wing skin. The easiest Way to do this is to make a spacer that you can place at the aft and underneath the level. My buddy Glenn had saved his spacer from his first airplane so I borrowed it to make my adjustments.  

  With the spacer and my 4 foot level and my digital level I worked my way along each wing at several different points checking the measurement. I had to make some small adjustments on both sides to get them just perfect.   

  

 With all three of those adjustments perfect I clamped the rears are in place. I then took the day off and came back at it the next day and re-did each of the measurements to doublecheck and triple check that they were perfect. After confirming that all the measurements remain the same I prepared to drill the rear spar to do this I used my drill cup and a #30 drill bit. The drill cup made sure that I drilled square to the surface. From there I stepped up using two readers and two drill bits to get the final size of 5/16″. 

   Now the wings are all set in their final position, hopefully the plane will fly straight and won’t have a heavy wing. Now that I have the wing secured in its position I can start to work on all the extra wing attach chores like rigging the ailerons, flaps and other items.