The Birth of a Taper Wing Waco

By Bob Patrick, McCall, ID

208.634.4824 (h) • E-mail: nx149tw@frontiernet.net

    I finished my Taper Wing Waco on September 19, 2005, after a 13-year time span (with many interruptions). Phil Coulson suggested I write an article on the history of the construction.  I was researching biplane types trying to decide what to build when I found out that Dave Allen was just finishing up a replica Waco Taper Wing. I visited Dave in Colorado four or five times and then decided this is what I want. I wanted a full-size biplane, a radial engine and something with a history. I really like the way it flies! The lively response and high sink rate on approach reminds me of the B727, which I spent 19 years flying.
    I purchased the plans and fuselage from Ernie Bode in Denver. After studying the plans for about 10 days, I began to realize that there were a lot of discrepancies. The distance between the centers of the spars at the butt rib on the chord line is 31 3/4”. This is a very critical measurement, as it must match with the same area on the center section butt rib and the butt rib of the wings. The full scale rib drawings had been copied numerous times, I’m sure, and had grown by over 1/2”. I had the measurement at the butt rib and the measurement at rib #12, and I also knew the spacing of the ribs. So, I lofted the whole wing on the shop floor with chalk line and recorded all the spacings at the center of the spar on the chord line. When I made my 12 wing rib jigs, I removed the error where the top capstrip and bottom capstrip were parallel. This solved the problem so I proceeded to build 57 ribs, with one extra from the center section for a wall hangar and conversation piece.
    I used T-88 glue. A hint: coat the whole inside of all gussets with T-88 to seal them so you wouldn’t have to varnish them twice with a little battery brush. I built the center section first, which is fairly standard construction. It has parallel straight spars and you just level the sawhorses and assemble.
    The first wing was a real learning experience. I built the upper left wing first. You can’t level the spars on a sawhorse because the spars taper. You can’t slide the ribs on to both spars because the ribs all have a different spacing. You put the ribs on the rear spar and then slide the front spar through the ribs, which takes a lot of juggling. You then have to level the spars on the chord line, which is the only true datum to use as a reference point. I made little blocks to nail to the sawhorses and clamped the spars to in a level position on the chord line. The wing is trammeled using the rear spar, as it is the only one at right angles to the ribs. I also used a plywood leading edge so the wing has to be very true, because once you glue that leading edge on, what you have is what you have to live with for eternity.
    I got a little carried away on the lower wings and decided to have landing and taxi lights. The old original Waco Taper Wing used a big Model A Ford type headlight mounted out by the interplane struts with a fairing on the back. I was able to fit modern style landing lights into the leading edge, outside the arc of the propeller. They adjust up and down and I made a Plexiglas lens by heating the sheet of Plexiglas in the oven and folding it over the wing leading edge just down the wing from the light opening.
    I think this is a good time to talk about the philosophy of building or restoring an airplane. Why are you doing it? It would be just as cheap to work a second job and have someone experienced in the field do it for you. Also, it would be much faster, and you would have a flying machine to use much quicker. So why do it ourselves? I did it because I wanted the fun of building the airplane myself. It’s not much fun if you set goals of building it in three years and push yourself until you burn out and give up. It’s also hard on the family, and you never finish the project. I worked on it as a hobby until I was at that famous 90% done stage and then dedicated three years to finishing the airplane. This worked for me.  I also received some advice from an experienced builder. Try to do something every day. It doesn’t have to be in the shop. It can be while you’re driving to work and you’re thinking and planning your next step or how to do a task. Don’t get hung up on a difficult area. Do something that is easy and come back to it in a few days. It always seems easier. If you don’t feel like doing the job you planned for that day, do something else that day. There is plenty to do and you can pick something fun and easy for the session and it will give you a shot of accomplishment.
Don’t plan your time and schedule of what you want to accomplish for each day. It never works out! Just work on it and have fun. If you continue to work, it will get finished. Have your own standards of quality. We have to meet some standard to have a safe airplane but that is far different than personal standards. Your personal standards should be what you are happy with, not to meet someone else’s standards. You will have more fun and end up with a better project if you work to your standards. We are of course, our own worst critic.
    I won’t go into the details of making all the wing assembly box areas and other details. I would suggest facing the access boxes with 1/2” plywood which gives a wider area for gluing fabric. This can’t be used on the front ones because they are into the curve of the leading edge and that won’t work. I glued the plywood leading edge and held it down with nailing strips, which are split and discarded and the nails pulled out. I used 3/32” on the leading edge and 1/16” on the tip where there is a compound curve. If you fasten the two straight edges first, the curved front will roll up into a compound curve very nicely.
Since plywood comes 8’ long and the wing is 11’6”, it requires two joints, which were made in a router box with a 1 to 10 taper giving you about a 1” lap. I placed the joints over a rib, which makes them very strong. I used aluminum for all the formers at the stations in the fuselage and aluminum hat metal for the stringers. I made a plywood baggage compartment, which allowed me to have the floor of the baggage compartment closer to the elevator push rod without the worry of baggage shifting and pushing down on the push rod.
    My VHF antenna is behind the baggage with the inspection hole in the belly and one under the turtle deck for access and removal. It is an “Advanced Aircraft Electronics” antenna and it is epoxied to a laminated stick attached top and bottom. The engine tends to block reception when more than 20 miles out and you’re copying ATIS information. If you turn 90° left or right, it works fine. I put two coaxial cables in for the antenna; one is standby in case the other wears out or fails. It’s a very hard place to get to.
    There are 13 metal panels that cover the fuselage from the back of the pilot’s seat to the firewall. The two panels at the front, which attach to the firewall, are the most difficult. The two gear fittings, flying wire attach points, lower outrigger gear strut and the cutout for the wing butt rib penetrate this panel. It does take some time to fit it. It also pulls down in somewhat of a compound curve at the firewall, which I reinforced underneath with additional .025” aluminum epoxy sandwiched and flush riveted.
    One area I would never attempt again is painting the instrument panels. I tried twice to get a textured finish and finally gave up and spent eight hours stripping them. I had the two instrument panels, which serve as formers, and the radio box powder coated for $100.00, and only lost three days labor on that learning curve.
    I think the most rewarding area is covering it all with fabric. I used the Superflite process, which worked very well. The primer undercoat is much faster than all that silver and it’s lighter. The empty weight for the airplane came in at 1,888 pounds.  I had a real problem trying to use a turbine drive paint and respirator HVLP unit. It was the highest quality made with a four-stage drive. It applied primer fine, but when it came to finish colors I couldn’t make it work satisfactorily. When you start the unit the air coming out of the spray gun is at room temperature. After you paint a while, the temperature will go to 110-degrees. This just cooks the paint and leaves a very lousy finish. The only way to even get somewhat of a satisfactory finish is have it running with the gun only, no paint until it is up to 110-degrees output temperature. Then thin the material 60% or more to provide a cooling effect and fill the cup and paint. This seemed like a jury-rigged way to paint.  I did a lot of research and finally bought an Anest Iwata HVLP spray gun. HVLP spray guns used to require a very large commercial type compressor because of the large volume of air required. They have been re-engineered and improved to the point where they operate very well from a small shop-type compressor. Binks, Devilbiss and other manufacturers also make comparable HVLP spray guns. My gun is much more capable than my ability.  One disadvantage of the HVLP system is that all the “over spray” falls on the floor as liquid and makes a real mess. You definitely have to cover the floor with plastic to catch it all and it has to be changed often. If you don’t change it when it dries, it starts flaking off and will float around the paint booth as you walk on it and drag your hoses through it.
    I also learned something about painting while I was doing all the research. First, you always read the articles on painting and they say PRACTICE, PRACTICE, PRACTICE. But they don’t tell you how to practice. Second, no one has ever told me where I should be looking and concentrating. The area behind the paint fan is where it is happening. I always wanted to watch where I was going instead of where I had been. You also have to see that area behind the fan in its reflection.  I have two things in the paint booth to set the gun and find the speed for moving forward and proper thinning. The first is a big piece of cardboard to adjust the fan and output. Then I have a piece of metal to paint for checking for proper thinning and forward speed. The PPG paint takes approximately 1/3 thinner at 70-degrees booth temperature. I used the same piece of scrap metal for all my painting. You just keep sanding it and prepping it when you prep your next paint session. The last trick I found out, partly from talking to a painter and then figured it out myself is to keep thinner in the booth to add after the first cross coat. The wet paint will suck the thinner out of the second cross coat and it won’t flow as well. It has to flow like water on a very clean windshield when you’re washing your car.
    I riveted 3030-1/2 inch aluminum fuel line to my cockpit openings underneath and covered the edge with tape and then plumbing insulation. There is also a .025” aluminum vertical brace under the rear cockpit opening on the sides about where everyone wants to put their hand when getting in and out. I trimmed the edge of the foam tube lengthwise to the proper angle and glued it down on the top of the cockpit opening. This allows you to roll the leather around it and pull it up tight with the leather lacing without it creeping and moving. Mary Sue found some leather lacing at Tandy’s. It was made from kangaroo, which is finished very nicely and is extremely strong.
    The radio installation wasn’t near as difficult as I had envisioned. I used the Becker VHF com and transponder. The com has its’ own built-in manual intercom, which you need so that you don’t get the sound of the wind whistling from a voice-activated microphone. I had it pre-wired and bench set and checked by a radio shop before installation and it works quite well. I have a radio box that mounts on the right sidewall and holds the radio, transponder and three circuit breakers. The extra circuit breaker is for an auxiliary power outlet to power a portable GPS, which has a plug-in at the bottom of the radio box.
I didn’t make a wiring diagram. I visualized the basic ideas in my head and worked from there. I set the battery solenoid and the starter solenoid side-by-side and bussed them together with a big copper strap. They are mounted on the right side of the firewall a little below center. The large copper strap is the first buss and the battery and alternator attaches to it. This saves running a heavy wire 8’ back to the rear cockpit and back. Then I just ran one circuit at a time and checked it when finished. Having the power there to test each circuit made it easier. I don’t remember any sparks flying, so I must have done it correctly the first time.
I do miss the building but I have some little changes and additions, which should keep me busy for a year or two.
    I flew the airplane for the first time on September 19, 2005, for 50 minutes from McCall, ID. I was planning on a one-hour flight but froze out. I didn’t have my longjohns on and my legs and feet got cold, mainly from wind blowing up my pants legs. I have since learned to put heavy rubber bands around my pants legs when it is cold. I do have one heat muff on the exhaust stack designated for cabin heat and it really helps in the front seat. I’m planning a canvas snap-on cover for the front cockpit with a zipper head opening, which will keep the heat in and the cold air out. Below 100 MPH I get some heat in the back but in a high-speed descent and the airspeed up around 150 MPH, that much moving air really sucks the heat out fast.  I flew the 25-hour test time off by October 15th. The latest we flew was for our Christmas card picture on Jug Handle Mountain, November 19th. I wore my Carhart insulated coveralls and Mary Sue wore her ski clothes.  We had a wonderful summer of flying to all the big events and put 52 hours on the airplane. The Arlington, WA, EAA Regional Fly-In was our test trip and we got packing and camping gear down on that fly-in. The big one was Oshkosh across the Idaho Mountains, over the Grand Tetons and the Big Horn Mountains to the friendly plains of the Midwest. You haven’t lived until you’ve crossed the Grand Tetons at 10,000’ looking up at the Grand Teton at 13,770’ from an open cockpit airplane.
I could write a lot more on our Oshkosh trip alone but will save it for another time. We were very fortunate at Arlington, receiving the Grand Champion plans built award. At Oshkosh we received the Reserve Champion plans built trophy.
    If there are members out there building a Taper Wing, feel free to contact me and I’ll try to help you in any way I can. We are thinking about some Waco and biplane gatherings for 2007 so maybe we’ll meet some of you there.

A champagne celebration after the first flight September 19, 2005. Mary Sue and Bob toast one another while Bob tries to thaw out.

Final assembly in the hangar. Cotter pins everywhere. Here Bob is putting cotter pins in the flying wire attachments.

Christmas card photo flight November 19, 2005. Bob and Mary Sue in their bright red Waco over the snow cover on Jug Handle Mountain.