Category Archives: Mid Fuselage

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. 
  

Instrument Panel

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Time:2 Hours

I had shipped my blank instrument panel up to SteinAir in Minnesota a couple of weeks ago to have them cut out the avionics on their CNC machine. It had arrived back this week and I had forgot to blog about it. They have all the avionics dimensions saved and can configure your panel any way you want. The benefit to having them cut out all the holes is that they also cut all the screw and rivet holes. My configuration has the two radios, intercom and autopilot panel very close to each other. There are four nutplates for each off them which means there are a lot of holes. I cleaned up all the edges and holes before countersinking for the rivets. After that work was done I temporarily screwed it in place. This will now give me the correct placement and length of the harnesses I will build.  

    
    
    
   
 So the idea is that after I have all the harnesses built and I buy the avionics I will be able to screw them in place and attach the harnesses and I will be good to go. 

Console’s and Wiring

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Time: 8 Hours

Had a great day in the shop today working on several tasks. First up was to rivet the two spar caps on so that I could put the consoles in place after finishing the wiring. These caps get blind riveted in place since you can’t get to the back side with them in place.  

   On the left side I added the two support brackets for the throttle quadrant.  

 With the caps in place I grabbed the left side console and worked on the wiring for the smoke system.   

 With as much of the wiring complete on the switches I put the console in place along with the throttle quadrant.  I fished all the wires from the switches into the gear tower and up behind the panel. 

 There were a few wires that needed to be made for the smoke system to be complete.  

   I moved on to the right side console.  
   The back of the panel area is getting to be a serious plate of spaghetti.  

 I figured now is a good time to start cleaning it up before I move on to another task. To do this i’m going to start building up all the wiring harness ends. I’m starting with the VP-X switch d-sub connector. This connector houses all the inputs from the switches on the consoles. It also has the flap control inputs from the pilots grip. An input from the starter contactor to allow a signal when the starter is engaged for an annunciation on instrument panel. 
     

  About eight more harnesses left to do to clean this area up. A lot of work done today and great progress. I also shipped out my pilot grip back to Tosten manufacturing to have a switch changed. On my flaps I had a switch that was off in the middle, momentary (spring loaded) in the down position and always on in the up position. This switch is designated like this (on)-off-on. With the VP-X you don’t want a switch that stays in the on position as it will continue to send power to the flap motor and you will get a runaway fault. Instead you need a momentary on both sides of the off position, (on)-off-(on). I emailed Tosten and they said send it and they would replace for free just pay the shipping. Great customer service for sure.