3.7 Hours -
Since I didn’t spend an hour making a new workbench today, I actually made descent progress on the airplane project. Of course, I haven’t even made a dent in the fuselage parts crate yet!
The first thing I did today was to match-drill the F-704C center sections to the F-704A forward bulkhead. Since this bulkhead is a critical component of the plane for stress distribution, the parts have to be in absolutely perfect alignment before drilling. To get the alignment just right, the big NAS1307 wing bolts are partially inserted before clecoing anything together. The NAS1307 bolts are close tolerance bolts, so they are very difficult to insert. I put a couple drops of air tool oil on the ends to make insertion a bit easier, and I only inserted them a little bit since there’s no need to put them all the way in (they’re about 4 inches long). Once the bolts were in (one on top and one on bottom), I put a few clecoes in and started drilling.
The big NAS1307 wing bolts are used to make sure the F-704C & D center sections are in perfect alignment with the bulkheads for final-drilling. They only need to go in a little bit at this stage, which is good because these suckers are tight!
Once the forward bulkhead was done, the F-704D center sections had to be match-drilled to the F-704B aft bulkhead. The F-704 shear bars also have to be drilled to the aft bulkhead, making it a little more involved than the forward bulkhead. To align the shear bars, I pulled out a couple more long bolts, inserted them through the shear bar and bulkhead, and then used a big clamp to lock the shear bar in position. Once the bar was clamped, I started drilling.
On the aft F-704B bulkhead, the shear bars are aligned with bolts and clamped in place for match-drilling.
An F-704G shear bar after drilling.
After match-drilling the shear bars, they are removed and the rivet holes are countersunk on the forward side. Since my countersink cage was already set up with a #30 cutter from the other day, countersinking four holes was pretty easy.
The F-704G shear bars are countersunk for a flush rivet on the forward side.
On to the control column. The F-633 control column mounts need a little fabrication work, so I located them in the parts bin and started marking out the location of the top hole. Once the top hole is drilled in the mount, they are bolted to the F-704B aft bulkhead, squared, and the bottom hole is back-drilled using the bulkhead as a guide. So far so good.
The F-633 control column mounts need some fabrication, They arrive from the factory zip-tied together through the bearing.
The top hole on the F-633 control column mounts is located and drilled.
The F-633 control column mounts are bolted to the bulkhead through the top hole, squared, and then the bottom hole is drilled using the bulkhead as a guide.
After the bolt holes are drilled on the F-633 control column mounts, Van’s suggests removing some material for weight savings. The amount of material to be removed is clearly laid out in the plans, so I marked the area to be removed and then made a rough cut with my band saw. By the time I got to the second mount, my band saw blade had had enough and was no longer cutting well, making the second mount much more challenging than the first. Looks like I’ll have to make a Home Depot run for a new blade before the band saw is used again.
Van's suggests removing material from the F-633 control column mounts for weight savings. The one on the left has been rough cut, while the one on the right has only been marked.
As usual, after the rough cuts were made, I used files, my belt sander, and the Scotchbrite wheel, to finish the edges of the mounts. This was no easy task since the mounts are made from some really thick aluminum. However, the finished product looked pretty good.
The F-633 control column mounts are finished. My band saw blade needs to be replaced after working on these!
Next, the F-633 control column mounts were re-bolted to the F-704B bulkhead, and the control column was installed. The instructions aren’t very clear about washer placement for the control column…they basically say to use enough for a tight fit, but not so many that movement of the column is stiff. The washer wrenches sure helped with washer placement here!
The control column base installed on the F-633 control column mounts.
After the control column was installed, I pulled out the control stick bases. These needed a little work before they could be installed. The brass bushings had to be removed, and the I.D. had to be enlarged to 1/4″ in order to accommodate an AN4 bolt. To open up the I.D. of the bushings, I made a small clamp out of a piece of 2 x 4. With the bushing held in the clamp, I could then use my drill press to open up the hole.
The hole in the center of the control stick brass bushings needs to be enlarged to 1/4". I made a wood clamp to hold the bushing while my drill press did it's thing.
Even after opening up the bushings, a little more work had to be done. The bushings were a little to long for the control column base, so I shortened them with a couple quick passes on the belt sander. Once shortened, they were still tight in the control column, but I could squeeze them into place. Before re-inserting the bushings in the control stick bases, I made sure everything was clean and then applied a little grease to the outside of the bushing.
With the bushings finished, I could finally install the control stick bases. Nothing complicated here…a bolt, washer, and castle nut, for each side. For now, I’m not installing the cotter pins since I know these will be removed more than a few times later down the road.
The control sticks are installed on the base and bulkhead. Now that it's assembled, it has to come off...but I'll leave it like this for tonight.
The plans say to remove the control column and stick bases as a unit, but leave the control column mounts installed on the bulkhead. Since I’ve read in a few places that the mounts have to come off eventually too, I’ll remove the whole assembly as a unit. It’s pretty obvious that the mounts are going to be in the way anyways. However, all of this is going to wait for another day.
