This is one of my favorite model aircraft but, the Spirit was not always one of my favorite because of it's lack of windscreen or cabin windows. In time it's unique classic looks won me over and now I can say, it ranks away up near the top. For years: while I was living on a farm with my very own flying strip, I would dust it off on that special day in May (21 May 1927) and put her up for another anniversary flight.
The kit was little more than a box of wood and a great set of plans; this was manufactured and sold when model aircraft enthusius were not afraid of a building challenge, in fact the build was for them at least half the fun.
She was always a bear to fly; something like the real thing I gather: from what I read over the years the Spirit was a modification of an existing Ryan aircraft called the Brougham; a conventional looking single engine transport with a range of only about 700 miles. The Lindbergh NYP aircraft would have to fly over 3000 miles nonstop so drastic modifications had to be made; all of which adversely affected the aircraft's flight characteristics. The number one problem was to increase the aircraft's range; to accomplish this a massive fuel tank was inserted into the forward cockpit. The addition of this fuel tank meant forward vision was impossible and windscreens and forward cockpit windows were eliminated, giving the Spirit that distinctive look. The look that I hated as a child: then the hobby shops and magazines were filled with examples and references to this aircraft; where do passengers sit? I wanted to know. The weight of the extra fuel meant that the wing area had to be increased to carry that extra load; this was done by adding an extra 6 feet to the overall span bringing it up to 46 feet. Seeing as the overall length of the fuselage is only slightly more than 26 feet its directional stability is marginal at the most. Flying this model was also not easy and as I recall it was a bear to control, requiring coordinated rudder, aileron and elevator just to get it to turn, without falling out of the sky. The landings too were always a struggle: with all that extra wing area it didn't want to sink in a normal downward glide slope unless, the speed was reduced to dangerous levels where the tail was on the verge of stalling. This very thing happened to me on at least one occasion, where a picture perfect approach developed into a nose dive into the ground.
Watch this video of a talented flyer control his Spirit in a stiff crosswind.
Sit in the Spirit's virtual Cockpit to get a feel of what it must have been like to sit there for 33 hours without sleep (when you want to see all 4 clips of this fantastic event you must click "Contact" to get a menue). The Flash Player may ask you permission to run, allow and you should be able to view the great clips. Click on the instruments to start the show.
Many years ago I purchased the collection of a deceased local modeler and among the many items included in the lot, was a partially completed Pica kit of the Waco YMF 3 biplane.
Fuselage Plan Sheet 1
Wing Plan Sheet 2
I have always admired the Waco line of biplanes although I admit that my knowledge of the various models in the Waco line-up was very limited to say the least. The Pica manufacturer describes the kit as a semi-scale 1/6 size of the Waco YMF-3.
It will be a long time before our Waco will be looking anything like the above.
My Webra 61 Speed fits perfectly in the wooden engine mount.
The plan calls for a single aileron servo to be mounted at the wing centreline moving the ailerons through a wire and bell crank system but we elected to actuate the ailerons with dual servos mounted at the control horne wing station.
The attachment of the interplane struts to the upper and lower wing panels is detailed above and below.
We elected to set up the ailerons with a servo mounted in each lower wing panel and located at approximately the control horn station. Since the wing section is not very deep we looked for the smallest pair of servo that we had, these happened to be a pair of never used Airtronic servos. To use these servos on our Spektrun radio system the pinout had to be modified to be compatible with Futaba connectors.
This process involved identifying the three output airtronic wires and re-attaching them to the appropriate location on the Futaba connector.
Through trial and error we discovered that the Airtronics lead with the white line is actually the positive. From there it was straight forward; the other end lead had to be the signal and the center lead is the negative.
Nylon hinge tange is used to attach the ailerons to the wing structure. I am skeptical about the integrity of this form of hinging but because there are three hinge points there will be a certain degree of redundancy if one fails.
Sheeting will be required around the servo cutouts to provide a surface to stick the covering material to.
Lower wing nearing completion.
Drilling holes for wing attachment is a job that I absolutely detest since there is just one chance to get it right. The wing and the fuselage have to be held in as near perfect alignment while drilling pilot holes for hold down bolts and front dowl. The care taken with this process seems to have paid off in this case; with the components attached in place, wing alignment is well within eye pleasing tolerances.
Hinging and mounting Tail Feathers
The Pica plans are not too clear on the details of the relationship between the vertical fin and the horizontal tail plane so we went to AeroFred.com and downloaded their Waco F-3 plan which is clearer on the positioning of the tail components.
Hinging and fitting Tail Feathers
The spars in the tail surfaces are made from spruce which is hard to slot so, we decided to use Robart Steel Point Hinge Points (#308). These hinges require drilled holes for insertion into the structure. The only time consuming procedure was the forming of the square recess required to bury the clevises which is essential for a minimum surface gap. The original Gorilla glue proved ideal for attaching the hinge points to the structure because if its gap filling qualities. Care not to use it too liberally proved a wise move. Soaking the moving clevises in baby oil to negate the chances of any excess glue inhibiting movement was also a good idea because, this very thing occurred with one of the hinges and the glue was easily removed because of the presence of the oil.
The hardest thing to date was adjusting and fitting the inter plane struts; each strut is attached at four separate points.
Sig Koverall was selected to cover this air-frame in an effort to control the cost.
Koverall is a cloth covering of the type used on full-scale aircraft, but in a lighter weight (1-1/4 oz. per sq. yd.) for models. Koverall can be used on almost all R/C models large or small. Its superior strength and low price has made Koverall a real favorite with builders of giant size models. It's the most economical cloth covering you can buy!
SIG Koverall is an uncoated, heat shrinkable plain fabric. It has no glue on it. To adhere Koverall to a model, you can either dope it on ala the traditional silk-and-dope method, or better yet, use SIG Stix-It heat activated covering adhesive (see below). Just brush a coat of Stix-It on the model framework, let it dry, then iron-on the Koverall just like you would a much more expensive iron-on fabric covering. Once the Koverall is stuck down around the edges, it can be shrunk perfectly tight with an iron or heat gun. Seal the Koverall with 1 - 2 coats of Sig Nitrate Clear Dope and then apply the finish of your choice.