Carlson Skunk Works

July 22nd, 2010

AMF-14H Maranda SN:1026 Construction Log July 22, 2010

Posted by Roger in AMF 14H Maranda SN1026, news

I was notified by Mike Lamb that his virus detection software complains about this site. I apologize for any inconvenience and would like you to know that I have reported the issue to my technical support staff (my son). My son informs me that there is a new version of WordPress available that should fix the issue and he will upgrade as soon as he has an opportunity.

As of this posting the site is now using the new version of WordPress and the latest version of MySQL. He ended up having to upgrade the database in order to accommodate the WordPress upgade.

Now to the news!

Progress has been happening!

All the ribs have been assembled and sanded. The trailing edge gusset slots have been cut and the notches for the leading edge reinforcement strip have been cut.

The wing spars have been reworked and now are using the correct thickness of plywood. The edges need to be sanded and I am working on marking where the ribs will attach and where the holes for attaching the fittings will be located.

The major coup of the summer was the acquisition of an engine! This is a real airplane engine, too. I came across a great deal on a Continental C85-12 with everything. It has two brand new Slick magnetos and harnesses, a starter, a generator, a carburetor with a heat box, the exhaust stacks and heat muffs. AND it cam on an inspection stand! The price was about half what I was estimating it would cost to build up a Corvair engine and just a bit over half of what a VW engine kit would have cost from Great Plains. The only down side is that it did not come with a log book. It was previously owned by an A&P instructor who had one of his classes overhaul it, so it is zero time since major. An A&P friend of mine did a compression test on it before I bought it. The cold compression results were 76, 68, 75, 72.

I suppose some pictures would be appropriate at this point.

This is the engine! It is shown on its stand. The propeller end of the engine is fitted into a prop hub that is bolted to the top of the stand. That means the engine is being stored nose down. I am keeping it under wraps (tarps and bags) to keep the dust off of it. The current plan is to build the fuselage next summer and actually mount the engine next fall.

Here are the ribs. I have them all together in the order that they will be positioned in the wings. The two root ribs still need a bit of work on their noses, but all the others are ready to be fitted to the spars.

Split front spar
This is what the front spars looked like after I cut the 1.5mm plywood web out of them. Pretty rough! I mounted the spars vertically on my sawhorses and used my circular saw to cut them apart. I tried to remove as much of the 1.5mm web as I could, but found that it was very difficult to keep the saw blade perfectly lined up with the plywood. I had to cut in as far as I could from each side, then finish splitting the spars with a hand saw. All together it took about 10 to 15 minutes per spar.

Once the spars were split, I needed to run them through the planer to get a level surface to work with. The first surface had to be prepared to mate with the new 2mm plywood web. When the new web was in place, I had to split things again and prepare the surface to accept replacement fir strips to return the spars to their designed thickness.

This is my precision planer. By using this notched board and clamping its lower end to the workbench, I am able to take cuts of 1/512 of an inch. Because Douglas Fir is prone to splinter and because there are a number of blocks with their grain running perpendicular to the length of the spars, I planed 1/128 of an inch on each pass. That seemed to work quite well although it took a fair amount of time to do the planing.

Here is what the spars look like after planing. There is a lot of difference!

All the spars are now ready to have the ribs fastened to them. However, that will have to wait for a couple of weeks. Tomorrow I am heading to AirVenture! This will be my first time and I am REALLY excited about it!!! Then my wife has scheduled a garage sale for August 14th, so I will need to clean up my work area and get the garage ready for the big sale when I get back from AirVenture. However, wing assembly is expected to commence the week of August 15th.

I have requested an N number for the plane. The FAA will allow builders to reserve an available N number, but it costs a bit. This time it cost $10, but there are some rule changes that are taking effect that will push the cost up more and require that I reapply every three years. I am waiting to get the letter from the FAA approving my request. When I do I will post the N number here.

The airplane also has a name. I have been telling people that I go home at lunch time and “make sawdust”, so I have decided to call the airplane “Sawdust”. Now I need to find a font and make a couple of decals with the name on them to fasten to the sides of the cowl.

For people wanting to see another Maranda in progress, check out Randy Holland’s site: He does a much better job of keeping his site up to date and has great pictures. Randy is just a bit ahead of where I am and has been a great encouragement and a wonderful resource when I have questions.