Building a Cozy MK IV Center Section Spar

Chapter 14 Center Section Spar















I started this chapter by purchasing some white particle board shelving. The shelving was used to build a fixture that I will need to build the main wing spar. I built the fixture and am now waiting on the remainder of my materials to arrive. I have epoxy coming up on the barge and sheets of foam coming USPO.


Today I built the jig to build the center spar in. It took all day to build and maintain the proper measurements.









I then added the "sticks" to the side of the jig per plans. I started checking to make sure each stick was square with the shelf and found that this would be a lot easier by adding three 1 x 3's to join everything together. You have to keep it in three sections due to the angles of the spar. This made the sticks check perfectly square to the shelf of the jig and guaranteed that they are straight with each other.







The US post office delivered my foam today after a little over two weeks enroute. Not bad for Alaska. My new batch of epoxy made it in yesterday on the barge so I am ready to roll.

So tonight I cut all the foam to size and test fit to the jig and did the final sanding to make the foam to fit perfect. I also put the relief in the foam called out in the plans. To do this I used my router and then sanded the relief smooth and sanded the radius to allow the fiberglass to lay properly.


I then microed the foam pieces together and cut pieces of Wicks heavy hazmat box cardboard to hold the foam out against the jig shown above untill the mico cures. I did put the ends on after this picture was taken.









Next I installed the spar box interior fiberglass layups. I started with the bi-directional fiberglass layer. I then installed the bulkheads and the bidirectional glass over them. Next I did the unidirectional layups for the hard points which the bolts that hold the wings onto the Cozy MK IV will pass through. I then installed the aluminum inserts at the hard points and the final layer of unidirectional fiberglass over the inserts. I then put weights on the inserts per plans. I let it cure for a day. This fiberglass session took me 5 hours to complete, this not counting having the fiberglass cloth already cut. I highly recommend using slow cure epoxy for this. I then trimmed the excess fiberglass off and this is what it looks like now.







I then laid out the top pieces on my bench and prepared them for fiberglass. I drew a long straight line on my bench to use to line the parts up. I used micro to join the two center parts together. I glassed them with BID and peel plied them. It looks like I fiberglassed everything together but there is a gap between the far piece and the two center pieces so them I can cut them apart.









I next with micro installed the last side of the box which will be the front. I weighted it down to be sure of a good contact.









While waiting for everything to cure I made my templates for cutting the spar pockets. To do this I glued the templates to plywood and cut them out with a jigsaw and sanded them to finish size.








After the spar box had a couple days to cure, I removed it from the jig.
I then sanded all the corners to make them square and clean. Then I laid out the toughs for the spar tape and used my router and roughed them in. Next I took my sanding block and sanded in the troughs to fit the templates. It took a little while to get them right.









Next I cut the 1" x 1/2" angles with my jig saw on the corners per plans. I used my sanding block to make the angles straight.
Next I laid out the aluminum hard points that will be used for attaching the wings and floxed the hard points in place. At this point I couldn't take it any longer and had to clean up the garage, there was foam dust everywhere.





 

I then cut the Uni directional fiberglass for the shear web. I then filled the holes in the foam with micro and installed the shear web, alternating the fiber direction per layer of fiberglass.
I then added the dams on the side of the spar box. These are used to hold the spar tape in place until the epoxy cures.







After that cured I applied the top spar cap. This layup took about 5 hours doing by myself. I fit all 11 layers the full length. The next day I sanded the radius on the edge of the spar cap and prepared for the bottom spar cap.

The next night after work I installed the lower spar cap. After the spar cap cured, I put a radius on the edge on the lower spar cap. Bellow is what it looks like to this point. I am very happy how it came out so far. The fiberglass work is getting a lot easier to do and make it look good.








The next layup took about 4 hours. It was the four layers of UNI (unidirectional fiberglass) the full length of the spar, alternating the fiber direction on every layer. I included in this layup the hard points for attaching the wing.

I floxed the aluminum plates in place and floxed the corners for a smooth transition for the fiberglass. I next installed the three layers of UNI fiberglass and the single layer of BID (bidirectional) fiberglass. I then applied the peal ply over all of that to give it the smooth look. I also peal plied all of the seams for a smooth finish.








The next day I trimmed all the edges and sanded any rough edges. I then cut the access holes that will allow me access to bolt the wing to the center spar. I probably measure all of these holes 3 times to make sure everything was in the right place. Too much work to screw it up now. Next I glassed the front side of the center spar with two layers of uni once again alternating the fiber direction and lapping it onto the side by one inch. I then peal plied all of the edges. After that cured, I made flox corners and glassed over the end caps. This finishes chapter 14 except for installing the center spare on the fusalage. I won’t be installing it into the fuselage until I absolutely have to in order to save room in the garage. I stored it out of the way and hopfuly will be installing it this winter.



          






The center spar at this point weighed 43 lbs. This doesnt seem too bad for the amount of fibergalss and epoxy that went into this part.


Now it is time to start on Chapter 13 on Monday, May 30, 2011.




If you have any questions, comments or concerns, feel free to email me @
Jfisher59@gci.net