Carlson Skunk Works

September 24th, 2012

AMF 14H MARANDA SN:1026 Making Sawdust September 24, 2012

Posted by Roger in AMF 14H Maranda SN1026, news

This week I have made a fair amount of progress, but on little things. All the wing fitting parts are now done except for the bolts. The good news is that I have a bunch of new pictures.

These are the mounting brackets for the left rear wing spar. The plans call for aluminum angle that is two inches wide on one side and one and a half inches wide on the other side. When I ordered the material all I could find was aluminum angle that was two inches wide on both sides. So my mounting brackets are a bit different from the plans. Also notice that at this point the brackets have just been cut to length.

Yesterday I trimmed the corners to finish the brackets. I started by finding a fender washer to use as a template. I used that to ensure the same amount of material on all sides of the hole. Then I just used a straight edge to lay out lines from the corners to the edge. Once that was done I cut the corners off the piece and deburred edges.

The fittings that go in the upper end of the rear strut were a bit interesting to make. The plans were unclear as to exact measurements and there is an angle on the end so the whole part is cut from 3/4″ x 2″ aluminum bar stock. What are the chances that I would be able to accurately cut a 3/4″ x 3/4″ section from the bar stock with my trusty hacksaw? NILL! Therefore I decided to drill a series of holes along the edge that needed to be cut to act as guides for the saw. By drilling these on the drill press I think I have a fair chance of having that edge be vertical.

So this is what it looks like after the excess material has been removed from the bar stock. This is still attached to the two foot long bar stock that I had ordered. I only need about seven or eight inches on each end, but that gives me enough material to make another set of these if needed. Having this on the end of the bar stock also provides a nice handle to use while I finish fitting the piece. This end has to slide into the strut. With a bit of filing it does slide in and out very nicely and maintains a snug fit.

Once the end was fitted to the strut the angle needed to be determined. I cut the end of the strut at the required angle last week when we fitted the wings to the fuselage. So what I did was mark the part of the fitting that fits into the brackets on the rear spar so that is was perpendicular to the end of the strut. This worked very nicely. The other issue was determining the length of the part that fit the spar brackets. I just took a wild guess and laid my small square against the end of the strut and marked the fitting on the other side of the square.

Cutting the fitting off of the bar stock was probably the most difficult part of this operation. I clamped the bar stock to my workbench and used my hacksaw, but cutting through the 3/4″ bar stock for two inches was a bit of a chore. Of course I wanted the end to be as close to square as possible, so I was being very careful with my cut as well.

When the roughed out and marked end had been separated from the bar stock I still needed to cut the top part to fit the spar brackets. Once that was done I put the fitting in the strut and held it in place in the bracket so I could mark where the hole needed to be drilled.

With everything in place and the fit is nice and snug. In fact, I may need to file a bit more from the sides of the fitting to make it slide into the spar bracket smoothly.

The wing is hanging from the ceiling after last week, but I thought I would just fit the struts to it to be sure the angles and lengths seemed to be about right. Things are looking pretty good from what I can see at this point. At a later date I will need to put the wings back on the fuselage and verify all the angles and fittings. However, that is still a ways away.

This is what I though I had a picture of when I did my last post, but found out that it was missing. This is what the rear spar mounting brackets are connected to on the inside of the fuselage. There is a flat plate on each side of the bulkhead. The plates are bolted together through the bulkhead. Against the bulkhead and the side of the fuselage is a 1″ x 1″ angle. The rear spar mounting brackets are bolted through the fuselage side to the angle. Getting all those holes to line up was a real challenge.

Like Randy, I found that I needed to add a piece of filler behind the angle to give the bolts holding the rear spar brackets something to clamp down on.

Now I need to measure all the holes and order the appropriate bolts.

September 16th, 2012

AMF 14H MARANDA SN:1026 Making Sawdust September 16, 2012

Posted by Roger in AMF 14H Maranda SN1026, news

Progress has been happening almost in spite of myself. The fuel tank is pretty much in the same place that it was on the last post, but I have been doing more thinking about how to go about installing it. So, in the mean time I decided to work on getting the wings installed.

I ordered struts from Carlson Aircraft, Inc. in Ohio. They are not related to me in any way that I know of. The struts arrived in about a week in a cardboard tube. Each strut comes in a long plastic sleeve. I left the sleeves on to protect the struts until the plane is done.

What needed to be done was to make the attachment brackets for the rear wing spars. The front spars attach to the windshield frame that Don welded up for me before I could put the sides together to make the fuselage. The rear attachment brackets require an aluminum plate to be installed on the front and back of the rear bulkhead and some aluminum angle to be drilled and installed. That all meant that I had to drill a bunch of holes straight through the bulkhead to allow the bolts to hold the plates and angles in their proper locations. I guess it is time for some pictures.

Well, since I don’t have any pictures of the individual parts, I will post some pictures of the plane as it stood yesterday evening about 6:00. The picture above shows the front view. Doug, a friend from EAA, came over to lend a hand and since he is a brick layer he offered to bring a couple of sets of scaffolding. This was great since each leg had a base that was adjustable up and down about two feet total. We put a 2 x 6 on the top of each scaffolding section and rested the ends of the spars on them. Then we adjusted the legs up and down to get the proper dihedral and washout.

Moving to the south just a bit gives a slightly different angle on things. The main struts are in place at this point and are actually holding up the front spar on each wing. The scaffolding is only supporting the rear spars and is maintaining the washout.

I stacked up my shop stools, some plywood and the box that my heat gun came in, to raise the tail wheel so the fuselage is basically level.

With the washout in place I measured and cut the left rear strut. It fit just fine, but I need to finish the top attachment piece that goes into the strut. Since it is now the correct length I can finish the top piece and put it into place in the strut.

I pulled the fuselage out into the driveway about 7:30 in the morning. At this point it is about 6:00 pm and we still need to remove the wings and hang them back on the ceiling in the garage, then break down the scaffolding for Doug, so he can head home for supper.

The plane is back in the garage and the garage has been vacuumed. There is even room for Marsha’s car. Now to figure out what I am going to attack next.