Things I would do differently
The purpose of this page is to pass in specific things I've figured out about building this particular aircraft. Some of these ideas may not translate to other aircraft, but
they made a big difference to me, and if I would have know these things before I started, they would have saved me huge amounts of grief and time. I pass them on
here for anyone who may find any of them helpful. Please remember that I am not an A&P mechanic and have never built an airplane before, so for some of you
experienced guys, some of these items may seem pretty obvious. The point is that I didn't know them beforehand and its very likely that some other builders out there
may not know this stuff either!
I'll be adding more info and photos later. This is just a start.
- Use the manufacturers suggested methods. I can't say enough good things about West System epoxy. When I started having problems with glue joints cracking
(not their fault - see my log) I called them up and they jumped all over the problem. They wanted samples of the batches of glue from each job and samples of fresh
glue. They wanted pictures and more samples. They had a meeting every Friday with several of their engineers and discussed my problem. They eventually figured
out that if I controlled my humidity issues and used their product the way they recommended, I wouldn't have any more problems. They sent me all sorts of guides
and manuals on best practices and I even get a magazine once in a while showing lots of pretty elaborate projects that other people are creating using their products.
The big thing that I discovered after reading their product guides is to use a thickener and create very large fillets on the glue joints. This creates a much larger
bonding area and eliminates the tight angles than can focus the various stresses into a very small area.
- Avoid Bake-offs with ice. (more to come)
- 2nd coats of epoxy. (more to come) Timing and pigment.
- Variable size hole cutter. I started trying to cut the lightening holes (there are a LOT of them) with hole saws or with a jig saw and then sanding to final shape. I
mentioned this to some old guys at an EAA meeting and they told me about this wonderful tool that lets you cut holes to any size you want. You just adjust the arm to
where you want it and you get perfect holes every time. Another little tidbit is that the plugs that come out when you cut the holes make great clamping pads.
- 4" to 6" angle grinder with a sanding disc. This was recommended to me by one of the other Tally-Ho builders. You can remove very large amounts of material
in a very short time. It also is surprisingly easy to very precise with it, allowing you to get very close to final shape very quickly, leaving only a little finish sanding to
do. The drawback is that it creates large amounts of very fine sawdust. But its often worth the trade off. When I use this tool I will often recruit a helper to stand
right next to me with a large shop vac and try to capture as much of the dust ass possible as I create it.
- Thimble Sander. This is the ultimate tool for shaping those inside corners on the bulkheads, ribs, etc. Its almost like this tool was designed specifically for making
- Laser Level (more to come)
- Detail Sander (more to come)
The "Tally-Ho" Plans
- Use the good stuff. The guy at my local hardwood shop was out of aircraft grade plywood and suggested some marine grade stuff. I talked with Terry and he
assured me that marine grade was fine for the fuselage bulkheads as they aren't actually stress bearing, they only create the shape for the skin and the skin caries the
loads. So I went ahead and used the marine grade stuff for most of the bulkheads. What a nightmare! I'll get the name of it and put here, but even Wicks and
Aircraft Spruce sell it. Its some dark wood from Africa that is manufactured in France. To me it feels much heavier and it splinters and splits like crazy. Even with
backing clamped in place it splintered when drilled or hole sawed. I spent large amounts of time patching up the splintered edges with epoxy. The aircraft grade birch
I got that came from Finland hardly ever splintered and had a much nicer finish, seemed lighter to me, and much stronger. There's no doubt that the dark marine
grade stuff is very pretty when finished, but I'm painting everything anyway. Its also cheaper, but not worth the trade-off at all. You'll never catch me using that stuff
- Wood shrinks when the humidity drops - A LOT!! If you read my log you'll see the extreme difficulties I had with humidity causing the wood to shrink as much as
5%. This probably won't apply to most builders, but I live where it gets really cold (-40 to -60F) for several moths out of the year. This completely removes the
humidity from the air and I've been told that in some situations its even referred to as negative humidity as it draws the moisture out of everything. This is especially
true of wood. There have been several occasions where visiting musicians have their instruments warp or crack within a day or two of arriving in town. I've
discovered that the owners of high end wooden aerobatic aircraft keep them stored in temperature and humidity controlled hangers. The only way to deal with too
little, or even too much humidity is to run humidifiers (or dehumidifiers) and pay great attention to sealing the wood. Terry was very adamant about this, but he was
concerned about too much moisture where he was from. I can tell you that I need to be sure I get everything sealed to keep the moisture in or the aircraft structure
will actually tear itself apart.
- Steam Works Wonders! (more to come)
- Overly precise dimension call outs. In several situations Terry handed the drawing of the plans off to a 3rd party. It looks like the guy putting the call outs for the
dimensions often "pulled the measurement" directly from the drawing using standard Autocad tools. This created very specific measurements that, if taken at face
value, will drive you nuts if you try to comply with them. You will often see measurements, especially for larger diameter holes or radiuses in 16ths, or even 32nds
that don't even need to be within an 8th to be fine. I spent an enormous amount of time on the jig fences trying to get the specified holes exactly positioned and cut to
the right size. I bought several sets of drill indexes and expensive hole saw kits to get some of the more unusual sizes that were called for in the plans. In retrospect,
the only reason for the holes in the fences are to allow you to install some of the stringers and longerons while the jig is still in place. Those holes could be ANY size
as long as they are large enough and don't weaken the structure of the bridge piece. Even if you get them wrong its an easy matter to grind them out a little bigger if
you need to when the time comes. There are other places where this occurs. So if the measurement seems overly precise, back off and look at the context and
decide if it really needs to be that way.
- Printing/Scaling errors. Check the full size templates! On more than one occasion I had cut out and finished shaping and sanding an expensive piece of wood only
to find it was the wrong size. At first I blamed the plans and thought bad things about Terry and his draftsman (I even called up and confronted Terry about it once)
only to find out it was my fault! The plans come on a CD as .PDF files that you either take to a copy store or plot out yourself if you have access to a standard
plotter. However, if you plot them out yourself you will find out that there are lots of settings available when it come to orienting the drawings on the roll paper, paper
size, etc. It turns out that on more than one occasion I somehow ended up with a type of "auto scaling" enabled when I printed a particular sheet. This doesn't make
too much difference on most of the plan sheets, but its critical on the full size template sheets. So before you use a template sheet as a template - BE SURE to
measure one of the drawings for accuracy. If the plan says its a full size template and the call out says its 4 inches, measure it and make sure it actually is 4 inches.
- Many metal piece templates don't have bend allowance included. (more to come)
- Elevator pulley bushings vs sealed bearings (more to come)
- Elevator hinges (more to come)
- Elevator and Stab hard points (more to come)