Friday, October 12, 2018

Fuselage, Part 5 Edge Distance

As others have said, the forward fuselage becomes an exercise in edge distance. This means the closeness of a hole to the edge of the aluminum. It is suppose to be 2 times the hole diameter from the center of the hole to the the edge. So a little fancy math gives 1 1/2 hole diameters from the edge of the hole to the edge of the metal.

This first became a problem for the F-623A clips that couple the mid and aft fuselages. In the picture you will see the plans-built version all primed and ready to go. The non-primed are the ones I remade to solve the edge distance problem as evident by the "x" on the part, where the hole would have ended up.

 Everything was going great until I arrived at the F-719 installation. These parts are "joggled" to overlap the F-904 bulkhead. My parts didn't fit very well; and the rivet would have been right at the jog.  I ended up adapting, as builders often do, and used a second angle piece as shown in the picture. I will round the edges so that these pieces play nice with the passengers. 
 Following others advice, I was very careful to measure all edge distances before drilling. Some are VERY close; but I failed when it came to the F-9101 gear attach web. I followed the plans and drilled the holes in the F-713 longeron on the "outside" center line, but this puts the hole in the F-9101 too close to the edge. I would recommend that the F-713 be drilled with the holes biased on the F-713 web to provide maximum edge distance for the F-9101.


I could trim back the F9101 web to make my F-713 holes line up with the skin holes again, but I am still left with an edge distance problem. The black circle just above the hand-model's thumb is where the F-713 holes should be; still plenty of edge distance.

So far the kit pieces do fit together very well. I think most of my trouble has been operator error. No more beer for you- Seinfeld




Sunday, September 2, 2018

Fuselage, Part 4

Much progress has been made on the fuselage. I realize this is a long build; much like the wings, I look at the instructions and see what I have accomplished and what I have left to go, and just gain a little more respect for all those who have gone before. I keep telling myself there are over a thousand flying, and at least one that has flown around the world. Thanks to all those trailblazers.

The fuse continues with the center section assembly. Much of it to plans, but the crotch belt hold downs were an update that is not explicitly called out in the instructions. I decided to do this while installing the ribs. This allowed me to use solid rivets. I also had to use the 90 degree drill adapter and a 12" #30 bit. I was able to use solid rivets due to my doing this as the center section was assembled. (The separate instructions assume a retrofit and used pulled rivets.) 


Riveting the center section had its difficult moments. It took some effort to get to the rivets for the center ribs and the center-rear bulkhead. If I was to do this again, I would start with the most central ribs and rivet from the center to the outside squeezing the rear and crotch belt supports, and using the rivet gun for the very front.

Once the ribs were in, I turned it up on the edge of the bench and most of the skin rivets were easy with my awesome helper holding the bar. I had to remove the control column brackets and 2 of the 4 seat belt anchors to get access.


To me it was not clear when to dress the R-915 side ribs. I did those after the structure and skin were riveted on and this worked out well. These must be fluted to match the curve of the side skins. I was able to use the prepunched holes and the seat floor edge to judge the fluting. They came out well.



After all this fun, here is the milestone shot. The one that shows real progress is being made. (At least until it comes time to take it apart to deburr and dimple.)
I realize I did not install the optional AHDRS mount in the aft fuselage. I am thinking I am going to put it up front to avoid more wires and tubing going through the center section. That is my story and I am sticking to it. ;-)



Saturday, July 14, 2018

Fuse, part 3

So I am working on the aft fuselage. Like many others, I had trouble with the F779 bottom fuse skin at the rear. This is really thick and pre bent. Well sort of.  I had trouble getting the prepunched holes to lie up between the F779 and the bulkheads F710, F711, and F712. I was determined to have these pieces fit without inviting my neighbor, Mr Armstrong, to come over. Finally got it all lined up.

The trick was tweaking F779. First I made a jig to get the sides bent more by hitting it with a rubber mallet on the end; I tried using a piece of pipe on the bends, but this didn't do much. Then I used the rolling trick from the rudder build to finish bending the curve to 90 degrees. The metal has a lot of spring back, so I couldn't due this by hand. Everything fits well now.


Friday, June 29, 2018

Fuse, part 2 of many

Bending longerons. Those words create fear, at least they did for me. I don't care to beat things with hammers, so I borrowed some longeron bending dies. I added scotch tape to the longerons and spread a thin coat of biolube from the aviation isle of  REI. I didn't have a good vise, so I used c-clamps and the old wing crate as a table. I taped the plan's template to the side of the crate. This worked out well.

Using the c clamps, I did the first pass moving the dies about 1 1/2" at a time. For the first longeron I had help and it went well with very little out of plane bending, but I went thru 12 "el cheapo" c-clamps. For the second longeron, I bought three drop forged c clamps. These are still usable afterwards so worked out better. The rear bend is actually much tighter than the rest, so I had to use three pieces of 1/64" model airplane ply to increase the bend radius of the die.

The second longeron bent easier using the better c clamps, but I had much more out of plane bending. Using some scrap wood and a 2" piece of drain pipe, I was able to roll the bend back into plane. Both are well with the 1/16" tolerance.


Sunday, June 3, 2018

Fuse, part 1

In looking at various build logs of others who have gone before, it seems the fuse takes just as long as the tail and wings combined. So I decided to use a gifted surplus Hobbs meter to keep track of my build time. Now I am depressed; my per week build time is no where near what I expected. So I have abandoned the Hobbs and am just trying to spend any free time on the plane. Anyone want to come by and paint a house while I build?

The big decision was whether to paint the interior pieces that show at this time. After much hemming and hawing, I have taken other's advice and decided to prime everything as I go and then re-prime and paint once the fuse is together. The crevices in seat back brackets will be hard to get to once assembled, so I will leave those cleco'd for now; those will end up having exposed rivets. This plan prevents me from having to worry about scuffing the paint during the build.

So the fuselage bulkheads are ready for assembly. The decision to prime did not add too much work, but it did add confusion. The various steps to prep the bulkheads had to be stopped while I built up a stack of parts to prime. This priming session was a long one, but went fairly quick.

Lawn Art:
 

Tuesday, April 10, 2018

Roadie Box

So the wings are done, but how to store them? So I decided to use the pieces of excellent wood from the shipping crates to modify the gifted wing stand and build a roadie box. This will store the wings and prevent any hangar rash. Here is a picture before the top and ends were attached. Like everything else I thought this would be a 1 day project, but alas, it took me a while longer.


Monday, March 5, 2018

Wings..done

Wings are done. Took me 13 months, but I am happy with the results. A big thank you to all those who helped. Now I need to remove the blue plastic and build a roadie box for long term storage. Yeah!




I will add the tips and avionics during the finishing stages; its too early to buy the avionics.

Here is a picture of the pitot and AoA tubes. I just heated them up and slide them on. The metal tube was prepared by plugging the tubing to keep the curd out, rounding the end, abrading the last 1/2" so the plastic tube would stick better, then removing the temporary plugs. Also visible is the bracket to hold the conduit away from the access cover screws.