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27-11-70 Aileron Spar

Builders Guide

27 Flight Controls

27-11 Ailerons (LD)

27-11-70 Aileron Spar (LD) 

Link to Builders Database for the Ailerons

Link to the most recent version of  27-11-70 Aileron Spar LD PDF drawing

The aileron spar is manufactured from 6061 T6 aluminum tube 1.5×.035
the spar will be manufactured from 2 pieces spliced together at the 138 inch position.

The spice tube will be manufactured from 6061 T6 aluminum tube 1.375×.049 or optional material .1375×.058. Although the holes for the spice tube are shown in the drawing we will not be drilling the rivet holes until the splice tube is placed inside of the 2 spar segments.

The splice sleeve needs to be installed centered on both the inboard and outboard sections of the aileron spar. Mark the 6 inch sleeve  at the 3 inch position with a magic marker to be used for positioning.

Before we can begin the process of assembling the 2 pieces of spar we need to make some reference marks down the length of the spar tubes. We do this by placing a channel or an L angle against the outside of the spar tube. This automatically aligns with the length of the tube because of the geometry of the L angle. We use some painters tape to hold it in place every couple of feet.

The next step is to take your magic marker and holding it in the exact same position down the length of the tube create a mark along the centerline of the tube.

The next step is we need to create an additional line down the tube that is 90° from the other lengthwise line. This is pretty simple to generate a line that is 90° with a little bit of simple math.

The tube diameter is 1.5 inches. The circumference of the tube is equal to (Pi)(D) = 3.1415 × 1.5 =  4.71  If we want to divide the circumference into 90° segments we can simply divide 360° divided by 90°= 4  We can now take our circumference of  4.71 ÷ 4 = 1.178″.

We can now take a scrap piece of paper and mark out the dimension of 1.178 Along the edge of the piece of paper.

We can now take the piece of paper and wrap it around the perimeter of the tube. Line up one of the marks with the original lengthwise line and we can now use the other mark on the piece of paper to generate the 90° mark.

If you needed to create more than a 90° mark you could simply duplicate the process for the 180° and the 270° Positions.

Refer to the spar spliced detailed drawing for the positioning of the splice and the rivets that will hold the spliced to the 2 spar segments.

We will insert our spar splice centered on the outboard edge of the aileron spar and drill and Cleco the 2 holes through the spar and the splice to initially position the spar splice.

Next we will take the outboard section of spar material, generate and alignment line along the length of the tube as we did with the inboard section of spar tube material. We will then but it up against the inboard section of spar and once again drilling Cleco at the appropriate positions.

We can then duplicate the process at 90°, 180°, and 270°  . This part of the process is a little bit tricky. Because the wall thickness of the spar material is .035 we end up with about a .030 clearance between the reinforcing sleeve and the inside diameter of the spar tube. One of the reasons that we have so many rivets holding the 2 tubes together is to make up for this clearance issue. Ensure that you maintain alignment between the 2 spar tubes that are being spliced together by placing it on the workbench during the construction process. Also ensure that the tube is straight from side to side by using a straight edge or even the L channel that you used during the process of marking the spar tubes.

Once you have riveted the 2 spar segments together we can proceed on to the next step.
The next step is to drill each one of the hinge location holes. These are 1/4 inch diameter holes but we start off with drilling them with a 3/16 inch drill bit and then once we have installed the reinforcing sleeves we will up-size the hole to 1/4 inch using a uni-bit. There are 4 hole locations in the spar. These will receive eyebolts that will function as the hinge. The inboard eye bolt will be attached with a nylon nut but all of the other eyebolts will need to have a nylon nut plate permanently attached to the spar. In the drawing for the Aileron Spar LD rearview you can see the 4 holes that are .25 inch diameter. These will be all referenced from the inboard edge of the wing spar. This is where accuracy counts because these holes have to line up precisely with the fork bolts that are installed on the trailing edge of the wing assembly. In fact if you are unsure about the accuracy of the fork bolts that you installed onto the wing assembly You may want to position your aileron spar along side of the rear spar with the fork bolts installed and double check the dimensions.
You will need to also Mark and drill the 3/16 inch holes labeled (.191) at the inboard end of the spar that are used for the attachment of the aileron control for. These holes will be located at .5 and it .2 inches from the inboard edge of the aileron spar and are on the same plane as the aileron hinge location holes.

We will mark the 4 aileron hinge bolt hole locations and drill completely through the spar using the V block and the drill press. We will drill with a 3/16 inch drill bit and then upsize the hole after putting the sleeves inside of the spar.

Special instructions apply to the installation of the very last rib rib #13 and the adjustment of the aileron spar length. The spar length has been left slightly long to accommodate the ability to move the outboard rib as close to the wing tip as possible to reduce the gap and improve the performance of the aircraft. Although this is trivial the ability to improve and slight ways makes a difference to many builders. If your building the aileron’s 1st you can simply build according to the drawings and cut 1/2 inch off of the end of the main spar at the wing tip location. If you have built the wing’s 1st you can position the spar onto the trailing edge of the wings and then adjust the position of rib #13. Once the rib has been positioned  with at least 1/8 of an inch gap between the outboard portion of the rib and the wing tip the remaining portion of the aileron spar can be trimmed off. You should leave a minimum of .4 inches edge distance from the center of the outboard hinge hole location and the trimmed off portion of the spar.

The aileron spar overview drawing shows the position of each one of the internal reinforcing members that are positioned for each of the hinge locations. Each one of the hinge locations have a 3 inch long 1.375×.049 reinforcement tube. The exception is the inboard section uses a 6 inch long 1.375×.049 reinforcement tube to accommodate the attachment of the aileron control for. We will be positioning each one of these reinforcement tube wanted a time starting with the outboard 1st.
In this picture here we see the trimmed off portion of the outboard spar and the hinge hole location drilled and ready for nut plate installation.

The outboard hinge location will need a nut plate installed. This is a special nut plate that has to rivets on one side of the hinge location primarily due to the close proximity to the edge of the material.

You will need to pre-drill Each of the nut plates to a #30 or 1/8 inch prior to installation.

Reinstall the nut plate onto the Aileron spar then drill, Cleco, and rivet the nut plate in position

Next we will proceed onto inserting the sleeve at the number 3 hinge location this is 119.846 inches from the inboard edge of the ailerons spar. Since the splice tube is in the way, we will need to insert the reinforcement tube from the inboard edge and slide it down into position. There are many ways to accomplish this we’ve come up with a couple of simple solutions to inserting the reinforcement tube.
We will pre-manufacture the 2 reinforcement tubes that are used for the center 2 hinge locations. It is manufactured from a 3 inch piece of 6061 T6 aluminum 1.375×.049. We will predrilled the .25 inch diameter hole to a 3/16 inch hole in the V block before inserting it into the spar and then we will upsize the hole to .25 after is positioned in place.

We will predrilled the reinforcement tube on the V block drilling a 3/16 inch hole completely through the center of the 3 inch long 1.375×.058 reinforcing tube. The next trick is to slide this 119.846 inches into the set inside of the spar and have it line up perfectly with the other hole. You can see in the picture below that we have predrilled the reinforcement sleeve And we have created a mark around the perimeter of the tube at the hole location so that as we slide the reinforcement down the inside of the spar if it rotates we will still be able to see where the hole location is by looking through the whole that is predrilled in the aileron spar.

There’s many ways to position the internal sleeve. You can take a stick or another piece of material and simply shove it down to the proper length based on a mark on the side of the stick.

You can stick a punch or and awl through the hole that you want to slide it to, Then just tilt the spar and slide the sleeve down until it hits the punch. 

Because the sleeve is quite a bit smaller than the diameter of the tube You can manipulate it with a punch through the hole for the hinge until you line it up correctly.

Once we have the internal sleeve in position we will Cleco one side with a 3/16 inch Cleco and then upsize the whole using a long snout Uni bit
We will then insert a 1/4 inch short bolt in the quarter-inch hole flip the spar over and upsize the adjacent side with the Uni bit

We can then proceed to install the 2 Leg nut plates. By inserting a AN4 Bolt through the nut plate line it up with the spar drilling it to 1/8 inch for each rivet hole and then installing the nut plate with a 4 – 2 stainless steel rivet on each leg.

We will duplicate this process for the number 2 hinge hole location located at 56.846 inches from the inboard edge of the ailerons Spar.

The final reinforcement tube that we need to install is the inboard reinforcement tube. This tube is manufactured from a 6 inch length of 6061 T6 aluminum  1.375×.049. Although the drawings showing all of the holes in the reinforcing sleeve it is not necessary to predrilled these holes as you can use the aileron spar as a drill guide once the sleeve is installed. The inboard aileron hinges located at 3.5 inches from the end of the aileron spar however this is the only aileron here’s the does not need a nut plate. It is located outside of the structure and as such we can use a nylon nut to attach the eye bolt.

This is the last step in the pre-manufacturing of the aileron spar. The next step is to continue construction of the aileron.

Click this link to visit the aileron assembly page

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About Brian Carpenter (255 Articles)
CEO Rainbow Aviation / Adventure Aircraft

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