Wednesday, August 15, 2012

Completing Spar Box Assembly Order Change

The last post left off with the mating of the aft spar with the assembly comprised of the forward spar, upper spar cap and lower spar cap to make up the spar box.

Now that the spar box has been Clecoed together it is time to Cleco the remaining two HS-1212 inspar ribs to the outboard ends of the spar box assembly to complete the “box”. Cleco the HS-1212  inspar ribs using the three rivet holes in the forward and aft spars. If the HS-1212 inspar ribs have been marked and orientated correctly, all the lightening holes should be in alignment so you can see through them.
                                   I placed a white sheet of paper at the end of the forward spar which can be seen
                                   from the other end of the spar box. Proper alignment, life is good.

Next step is to Cleco the HS-1209 spar cap spacers to the upper HS-1211 spar cap/HS-1212 inspar rib assembly. Repeat this step on the lower spar cap. All four HS-1211 cap spacers are now ready for riveting using the solid rivets called out in the plans. Rivet away!
                                               HS-1211 spar cap spacers in place and ready for riveting to the
                                               upper and lower spar cap/inspar rib assembly.

It is now time to begin making the spar box assembly a permanent structure and catching back up with Van’s plans. Once the HS-1212 inspar ribs have been checked and verified for correct orientation, riveting of the box assembly can begin by riveting the HS-1203 aft spar to the two intermost HS-1212 inspar ribs with LP4-3 pop rivets. (Remember in the previous post I made the decision to place solid rivets in the forward spar at this location, so the aft spar will get the pop rivets. Should a builder decided to do it the other way around; he/she would be placing pop rivets at this time but into the forward spar).
                   Riveting the HS-1203 aft spar onto the two intermost HS-1212 inspar ribs with LP4-3 pop rivets.

For the next phase of the spar box assembly, follow the instructions in the plans on page 9-05 Step 4 and set all 12 of the CS4-4 rivets into the countersunk holes made in the HS-1202 and HS-1203 spars way earlier in the plans (6 locations on top/6 on bottom).
                                    Setting the CS4-4 rivets, called out in the plans, into the spar box assembly.

Time to get some rivets into the two outermost HS-1212 inspar ribs. Note: A second reminder - to prevent the thin flanges from lifting during the riveting with solid rivets, remember to slide a small piece of vinyl tubing or a rubber “O” ring over the shaft of the rivet tall enough to compress the parts together before the rivet begins to set. This makes consistently tight joints.

Cleco two HS-1214 clips onto the HS-1203 aft spar at each outer HS-1212 inspar rib … ensure correct orientation per the plans and rivet with solid rivets. The upper and lower rivets are easy to set using a longeron yoke… however the center rivet may need to get a pop rivet which is what I was originally planning on doing. But good fortune was upon me and was able to set the center rivet with a hand squeezer and 1 ½ inch yoke going through the lightening hole. It was a very tight fit but doable.
                                    Riveting the HS-1214 clips to the HS-1203 aft spar and outboard HS-1212
                                    inspar rib with solid rivets.

Now would be a good time to rivet the two remaining HS-1214 clips to the outer ends of the HS-1203 aft spar with solid rivets making sure of correct orientation per the plans.
                           Completed HS-1203 aft spar with all six HS-1214 rib clips attached with solid rivets.

Now that the spar box riveting is completed for the HS-1203 aft spar, it is time to finish up the front spar by Clecoing two HS-1204 ribs onto the HS-1202 forward spar at each outboard HS-1212 inspar rib. Refer to the plans for correct rib orientation. Rivet the upper and lower flange holes with solid rivets first because the center hole may require a pop rivet if you can’t get a squeezer on the rivet. I was able to set a solid rivet but it was tight.
                            HS-1204 rib riveted onto the HS-1202 forward spar at the outer HS-1212 inspar rib.

Huston We Have A Problem - To make room for the pneumatic squeezer a Cleco was placed inside the two spars and …..
                                   Not one of the finer moments at DOG Aviation, the assembly crew (me) managed
                                   to get a pair of Cleco pliers stuck inside the forward and aft spars.

The pliers were finally removed without destroying anything except my pride… but it was not easy, they were wedged in there real good and it was tough getting the leverage to compress them enough to move them, yet alone remove them … it resulted in a time sucking abyss.
                     A proud moment at DOG Aviation, the completed stabilator spar box assembly mostly comprised
                     of solid rivets. It took some time to figure out but the results make it all worth while.

Now that there are four HS-1204 ribs riveted onto the forward spar, the stabilator spar box is complete and building will resume per Van’s plans. Of course, all of the ribs that will attach to the aft spar’s rib clips will be attached with solid rivets, the access is good.  The remaining ribs that will attach to the front spar will also receive solid rivets where possible and will be documented in future Blog posts.