First thing I needed to do was trim the bottom of the winglets to match the contour of the wing's airfoil. Luckily, there is a template located on the full-scale drawings page A11. Here I am aligning the template with the leading and bottom edges.
Used a pencil to trace the template outline...
Dremel wheel to cut the fiberglass...
This exposed the foam.. being careful to not cut the com antenna cable at the leading edge!
Used a knife to trim the foam off... did the best I could to keep the knife perpendicular to the winglet's surface...
Then used the dremel wheel to finish cutting the airfoil contour...
I should note that I also had to trim the top of the winglet. This
is because I purchased my cores from Eureka CNC. They leave the winglet extra
tall on purpose so you can shape the winglet top however you like. Since I plan
on having a flat top, I decided to simply cut it per plan's dimensions.
Here is the tricky part: the original plans give you the trailing
edge length (48") and then shows the top corner forms a 78.64 degree angle
with the top. I should probably invest in a protractor, but since I didn't have one... I used a little trigonometry.
I measured 48" inches along the trailing edge from the bottom of the winglet. I then drew a line 90 degrees from the trailing edge. I measured 7" along this line and then measured 1.41" perpendicular to it... this gave me the 78.64 degrees I needed... extended the line and cut the top! (I later noticed I could have just as easily drawn a line parallel to the top, but I wasn't sure if the top was cut at the same angle as the plans called for.)
I should note here that the 48" dimension does NOT include the 1" cap. This is important because when mounting the winglets onto the wing, the C dimension on Page 20-2 is referenced from this point (referenced from 49" to the bottom corner).
Here I am using the multi-tool to trim the winglet top...
Ta-daaaa! Winglet trimmed to proper height!
We then of course had to repeat all of this for the other winglet....
Moving on... it was now time to figure out where the winglets will be mounted. Using a level as the plans say, we measured 4.5" aft of the wing's leading edge... I taped a drill bit to the level to make it easier to know where to butt the ruler up against (since the wing's leading edge has a sweep and the level has a flat surface).
At 4.5" aft of the leading edge, I made a mark. This is where the leading edge of the winglet goes. I also made a mark where I needed to trim a small bit of fiberglass so the com antenna cable would have a place to slide in.. you'll see what I mean below...
Here we are presenting the winglet in place... dry run... aligning the leading edge with the 4.5" mark...
Here is a good shot showing why I needed to trim a bit of the fiberglass aft of the 4.5" mark to let the com antenna cable slide in...
We positioned a bunch of scrap foam under the winglet's trailing edge to help hold the winglet in place while we measured the A, B and C dimensions the plans give.. (actually the dimensions are found in the CP's since they forgot to publish them in the plans.)
The plans use the inboard top corner of the aileron as the reference point... it then wants us to measure the distance from this point to the LEADING edge of the bottom winglet (dim "A"), reference point to the TRAILING edge of the bottom winglet (dim "B"), and lastly from the reference point to the top of the trailing edge (dim "C"). Note that I still have not added the 1" cap to the top of the winglet, so that needs to be taken into account when measuring the C dimension to the top trailing edge of the winglet.
We used duct tape to hold the measuring tape exactly on the aileron reference point (starting +10 inches so that it would be more accurate then using the tape measure's tip).
And then positioned the trailing edge of the winglet exactly where it needed to be (note that B=108.35... but since I positioned the tape measure at WPRP at 10"... I had to put the bottom of the trailing edge at 118.35).
After checking, double checking and checking some more... I traced the winglet's outline onto the wing.
A good shot showing the winglet's outline on the wing's top surface...
And of course, this had to be repeated for the other wing...
Happy with the outlines, it was now time to trim the wing tips... dremel wheel to the rescue...
I took the same approach as trimming the winglet bottoms... removed the top surface first... then the foam.. then the bottom skin... of course, the wing was a little more complicated because there is a spar in the way...
Used the multi-tool to carve the section of the spar away... let me tell you, conducting surgery on the wing's main spar is an adrenaline rich activity!!
With the spar trimmed up, it was now time to trim the bottom skin...
Clearly marked it with a sharpie...
And used the dremel wheel to cut it...
Made sure to not trim the rudder conduit for now...
Ah yes, and of course, repeat for the other wing...
With the wing tips trimmed up, it was time to carve the flox corners. Do not underestimate the amount of time it takes to perform this step! I probably spent 10+ hours on this. First task was to mark how deep the inside flox corners go... this is a 2" deep flox corner...
I then used the dremel to mill out the foam (remember, on the inside corner goes 2" deep)...
The dremel only removed the foam, I then needed to remove the micro that was stuck to the fiberglass... this part is exhausting!
Just when I thought I was done, I remembered there is another winglet that needs prepping! When that was complete, I moved on to milling the flox corners on the wing...
Similar procedure here... used the dremel to remove the foam.. and a metal file to remove all the micro...
And just when I thought I was done... I remembered that airplanes have TWO wings!!! Aaaand do it again...
I then focused on the smaller, normal flox corners that go on the outside corners...
Smaller outside flox corners getting prepped on the winglets...
I wanted to make sure that ALL the micro was removed... so I made this tool using a popsicle stick and sandpaper...
It was the "magic miracle worker"! Required a lot of patience, but after an hour or two of sanding, all micro was gone!
With the wing tips and winglets prepped, the winglets were now ready to be bondo'd onto the wings... we repositioned them in place, measuring the A, B and C dimensions again... and used duct tape to temporarily lock them in place.
I then peeled the duct tape back at the root to allow me to apply the bondo blobs... I sanded the surfaces first to make sure the bondo would have a good bite...
Here's a shot showing how I used a bunch of shims to help hold the winglet in place while the bondo blobs were applied...
I made tick marks on the 2x1 and surfaces so that I knew exactly where the 2x1 needed to be locked in...
After checking, rechecking and checking again the A, B and C dimensions... I mixed up some bondo and blobbed it on...
Waited a few minutes for it to cure before moving on to the 2x1...
Removed the duct tape on the base of the 2x1 and bondo'd it in place... using the tick mark to know exactly where it needed to be...
Waited for it to dry, and then bondo'd the top of the 2x1...
The winglet was now "locked in place" with bondo... and ready for the inside layups!
Wow!! She is starting to look like one sexy airplane!!!
1 comment:
Looking Good!
Barry
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