Carlson Skunk Works

June 20th, 2011

AMF 14H Maranda SN:1026 Making Sawdust June 20, 2011

Posted by Roger in AMF 14H Maranda SN1026, news

Almost a month since my last post, but thing have progressed nicely. I now have a fuselage! So, let me fill you in on what has been happening.

Windshield Frame in Jig

The last time I was discussing the windshield frame, so here it is all set in its jig, ready to be welded. I ended up cutting the lower back corners off of the jig in order to get it to fit under the bed cover for my pickup. Then it was off to Minnesota to see my brother in law, Don, and get this welded.

I am not a welder. I have played with welding just a little bit, but Don is a professional welder and a welding teacher. It took him less than two hours to do all the welding for this piece.

Windshield Frame in place

Here is how the finished product will fit in the plane. The sides are only clamped to the bulkhead to hold things in place. The firewall has not bee built yet, so I have a couple of pieces of plywood holding the front end of the windshield frame in place to give a better idea of how it will fit.

This is a little different angle on the same subject showing more of the side of the fuselage and the windshield frame. Don sure did a nice job!

One of the things that I didn’t think about was that welding leaves a bead along the welded joint. This is good from a strength standpoint, but it means that I had to rasp away a bit of wood to allow the metal bracket to fit to the fuselage side tightly. Not a problem. I just got out my trusty rasp and gently removed what was required. Then I applied two coats of wood sealer.

I found some wood sealer that advertised “water clean up”. Well, it was worth a try. I was very plesantly surprised by this product. I think the brand is Valvethane or something like that. Anyway, I bought it quite a while ago and it had not settled. A quick stir with a stick and I applied the first coat. The color is sort of milky, but there is very little if any odor. The brush rinsed out quickly with warm water. I applied this in the morning and by lunch time it was dry. A quick sanding and things were ready for the second coat.

I expected the brush to be somewhat stiff like I often find brushes that have been used to apply latex paint. The brush was soft like it was brand new! The second coat went on smoothly and quickly and the brush cleaned up quickly and thoroughly. The second coat was dry in about an hour and the brush was still like new. I am very sold on this product.

I put some more finishing touches on the fuselage sides before assembly. I wanted to be sure that the side windows were identical, so I clamped the sides together with the outsides facing each other. Then I drew lines 1 1/2″ in from the frame pieces all around. I think rounded corners look nicer and more finished than sharp corners, so I took a spray paint can and used it as my template for the corner radiuses. When I had everything marked I tried out the scrollsaw attachement to my Dremel tool and used it to cut the hole. It worked very well. A bit of sanding and the holes were finished.

The next step was to mark the locations for the bulkheads on each side. Now I didn’t get pictures of this portion of construction, but you can see the result above. I actually assembled the fuselage upside down. The main bulkhead needed to be flush with the bottom of the fuselage sides and a gusset was applied to hold them together. Ensuring the proper fit worked best with the fuselage upside down.

Since things were bottom up, I installed the bottom cross pieces which stiffened the whole assembly. When that was done I turned the fuselage right side up and am now working on the top portion.

The fuselage looks quite large and it will seat two people, but the way it is constructed makes it quite light. I am able to lift it on and off of the worktable by myself. However, it won’t be too long before I will need to take the table apart so I can have more room to work on it lower down. At this point I put it on the floor when I am working on it and I put it on the table when my wife’s car needs to be put in the garage.

The thing that I am mulling over at present is whether the upper cross pieces should be fitted between the upper longerons, or if they should be positioned on the fuselage side above the longerons. Right now I am thinking that on the longerons would provide the most strength, but I will wait and see what some of the other builders say about it.

Of course, one of the most important pieces is the tailpost. This is where the fin will fasten to the fuselage. The large hole is to allow clearance around the nut for the bolt that fastens the hinge to the fin. The hinge connects the rudder to the fin. So, for this time, this is the end.