Chapter Project – George Laporte's Pitts S-1C
– by Bill Evans

During 2009, Canada's Centennial of Flight, an early member of EAA 266, George Laporte, offered his Pitts S-1C project to the chapter at no cost with the provision that we would make something useful out of it.

The Survey

The 2009 Directors briefly surveyed the project and decided that here was something worthwhile and that it should be kept. The fuselage is tack welded and on its gear. The horizontal stabilizers have been fabricated and there is sufficient tubing left to fabricate the vertical fin and tail control surfaces. A complete set of plans is included. The lower wing is complete, the wing ribs for the upper wing are assembled and there is sufficient wood to complete the upper wing. Marc Clement has offered his preliminary opinion that there is likely no penetrating rust in the 4130 tubing. A further inspection after cleaning will be necessary before priming. Michel Moreau has shown the lower wings to André Letourneau and he felt that they were of acceptable materials and good construction. The main landing gear includes axles, wheels and drum brakes. The drum brakes might not be adequate for a flying aircraft. There are a few 60 year-old instruments. It is not likely that these would be useable.
Michel Moreau has offered the limited use of his garage (summer 2010) to fabricate the structure of the upper wing. Marc Clement has offered to complete the welding of the fuselage structure if we clean the surface rust and redo any of the 50 year-old tack-welds. Another member has offered to fabricate the fuel tank out of aluminum. Gord Larsen has offered the use of his gas compressor to sand blast the fuselage. Bill Evans will supply sand blasting equipment and glass bead. We have been offered money, materials and time by skilled members, in a number of aircraft technical fields. So all the elements are in place to make major progress on this project. What is required is manpower and enthusiasm.

Next Steps

It has been decided to start by specifying two activities and proceeding with them, after which further activities will be identified once we have willing participants. They are as follows:
1) Sandblast the fuselage, inspect and prime temporarily pending finish welding. The interior of the fuselage tubing could also be preserved with preservative and linseed oil to prevent future rust. Gord Larsen has offered his facility and compressor at Lancaster for the sandblasting. Then Marc Clement will complete the welding. If we had a suitable steel primer it could also be primed at the same time.
2) Fabricate the upper wings with the existing wing ribs (already assembled) and spar stock that André Letourneau has offered to cut to size.

Other Needs

It would be advantageous to obtain any available documentation on building a Pitts, such as type club news letters etc. Any documents pertaining to the type and if it exists a builders manual would be welcome. Would any of you find and donate these items?

Volunteers

Given our average age, the project may be too much for most of the retired members to attempt alone. Together the project becomes much more viable and the timeline becomes realistic. Finally Iron sharpens Iron; the group members inspire each other to build.
One homebuilder wrote this, “Build Something in your lifetime. Make your mark in aircraft metals. Leave a legacy behind for others.” Day by day we can make this aircraft happen. Please consider joining.

Bill Evans
Pitts S-1 Project Leader.
Phone 514-907-4919 email: wwevans@enter-net.com

Photos and updates below...

Fuselage as received, complete with a few years of surface rust

Fuselage on its wheels and after many hours of sandblasting and sanding

May 21, 2010: It took about a week of steady work, but the fuselage, stabilizers and landing gear have been rough sanded and then sand blasted. Thanks to Michel Moreau, David Cyr, Gord Larsen, Hank Smulders, Ross Holden and anyone else who helped. Perhaps 30 man hours were expended, admittedly most of them mine. We consumed 3 rolls of emery cloth and perhaps 5 X 30kg bags of sand. The fuselage is presently at Michel Moreau's. The rest of the fuselage related parts are at my place. Next week we hope that Marc Clement will be able to re-do the welding as required and complete those parts that have been tacked. Once the welding is completed it will be primed. The primer is not yet chosen. The spruce for the upper wing spars is drying at Beloil, awaiting cutting. I bought a pair of cast aluminum rudder pedals at S&F, but have decided against using them on my Sonerai. I'll adapt the pedals I have to better suit me. My Sonerai passed engine run today, thence to be rigged and flown from Cornwall again this year. Thus we will soon have another bay for Pitts work this summer. Bill Evans

June 8, 2010: A Fuselage Question: Our current challenge with the project is to determine if the fuselage is as strong as the plans design and will it pass inspection. As it turns out, the longerons were cut in sections; cut at each bulkhead, (whereas the plans indicate a solid length from firewall to tail section, which requires bending the longerons during the welding process). Finger plates were welded over the joints to reinforce the longerons, but there is opinion that this does not comply with standards. Bill has researched repair procedures and has found the following in support of finger plates.

Bill read AC43.13 and found a procedure for repairing tubular 4130 structures. A drawing describing finger plates can be seen here. Bill believes that there is no practical or regulatory difference between an approved repair to a tubular structure, whether the repair is implemented before or after a Special C of A is issued. AC43.13 applies and is accepted by Transport Canada.

AC 43.13 - 1B Change 1
4-91. REPAIR OF TUBULAR MEMBERS.
a. Inspection. Prior to repairing tubular members, carefully examine the structure surrounding any visible damage to insure that no secondary damage remains undetected. Secondary damage may be produced in some structure, remote from the location of the primary damage, by the transmission of the damaging load along the tube. Damage of this nature usually occurs where the most abrupt change in direction of load travel is experienced. If this damage remains undetected, subsequent normal loads may cause failure of the part.
b. Location and Alignment of Welds. Unless otherwise noted, welded steel tubing may be spliced or repaired at any location along the length of the tube. To avoid distortion, pay particular attention to the proper fit and alignment.
c. Members Dented at a Cluster. Repair dents at a steel-tube cluster joint by welding a specially formed steel patch plate over the dented area and surrounding tubes. (See figure 4-34.) To prepare the patch plate, cut a section of steel sheet of the same material and thickness as the heaviest tube damaged. Trim the reinforcement plate so that the fingers extend over the tubes a minimum of 1.5 times the respective tube diameter. (See figure 4-34.) Remove all the existing finish on the damaged cluster-joint area to be covered by the reinforcement plate. The reinforcement plate may be formed before any welding is attempted, or it may be cut and tack-welded to one or more of the tubes in the cluster joint, then heated and formed around the joint to produce a smooth contour. Apply sufficient heat to the plate while forming so that there is generally a gap of no more than 1/16 inch from the contour of the joint to the plate. In this operation avoid unnecessary heating, and exercise care to prevent damage at the point of the angle formed by any two adjacent fingers of the plate. After the plate is formed and tack welded to the cluster joint, weld all the plate edges to the cluster joint.

Finger plates on longerons at bulkhead stations where the longerons are segmented and welded (to facilitate bending the longerons along the length of the fusselage)

November 21, 2010: This update summarizes the fuselage work done over the summer 2010 and thus fall this fall.

Gord Larsen loaned us his work space and compressor at Lancaster Air Park so the fuselage and landing gear could be sand blasted in preparation for further welding and subsequent painting. This was in the summer.

Since that time, Ross Holden volunteered a couple of days to complete the welding of those fuselage parts which had been tacked on as well as some parts fabricated by Bill Evans. The result is that Ross completed the wending on 50 parts and fittings, including six finger doublers installed at clusters. Some fuselage tubing clusters had finger doublers already installed. It was an easy decision to install 6 more to ensure uniformity of fuselage design. This welding occurred on November 13 and 20, 2010.

You would think that 50 parts would complete the fuselage since the fuselage was one piece and appeared to be well advanced when we accepted the project. On November 19, I compared the fuselage drawing to the fuselage and found that we still need some 37 fuselage parts. Having restored my Sonerai this came as no shock.

These comprise fairing clips, fuel component mounting brackets, four structural tubes for the empennage, seat belt attachment plates, flying wire attach fittings, two parts to locate and retain the tail wheel assembly, cowling supports, bulkhead attach fittings, fairlead bushings, and the mounting tubes and sleeves for the control column and the rudder pedals as well as the brakes. There are about 37 parts to locate, or fabricate and install.

I am reminded that Michel Moreau and David Cyr also are working on the Pitts; in their case the upper wing. The upper wing is being assembled at this time, with the spars and all the ribs ready for gluing.

Members and other pilots continue to donate components to the project. Paul Joncas donated at Comm transceiver and a Radar transponder. Harvey Reid donated an Airpath compass to the project. These additions are most welcome. Please think of the Pitts project at this time. There are a great many things needed. If you can't think of anything, gifts of cash are always both welcome and appropriate.

Bill Evans

December 6, 2010:

Mark Zablocki and I were able to continue the fuselage TIG welding on Dec 4, Saturday afternoon. Three more areas were completed. I was so impressed with Mark's mastery of TIG welding that we asked him to weld critical fuselage components for the Pitts S-1C. In the photo shown below you can see the fitting which attaches both the lower wing and the main landing gear aft strut. You can see the heat control, 100% penetration and perfect bead development in his welds. (The shiny surface appears because preservative oil has been applied to the fuselage structure to prevent rust.)

The Rudder pedal hinges were positioned, aligned and installed. They will be reamed and bushed later if needed.

Two plates were installed to receive the aileron/elevator torque tube and control stick. Because it involves less weight and has superior bearing retention it is decided to use the latest torque tube design: a pair of split aluminum blocks to locate and retain the torque tube pivot bearings. This also helps to ensure very smooth aileron control.

The fuselage requires a cluster of 6 small steel tubes to strengthen and stiffen the tailwheel attachment, the stabilizer attachment as well as to strengthen the lower attachment tabs for the stabilizer flying wires. This was accomplished by creating a V cluster which attaches to the rudder post, then installing the cluster with 2 other tubes aligned and parallel. Finally the remaining 2 tubes are installed between the upper stringer at the stabilizer forward spar, and the notches where the cluster joins the fuselage diagonal tubes. The geometry seems to have been well engineered, and the 6 tubes together with the primary tubes form a very rugged steel tube truss.

The installation was accomplished by tacking the 6 tubes in place, then verifying the tube placement and alignment. Finally the whole thing is TIG welded in place. This part of the welding took at least 2 hours of solid work. The sturdiness of the result is evident.

Mark assured me that he was worn out by the end of this work, so we stopped at that point.

If needed , the fuselage for the S-1C could now be fabric covered, doped and painted. Yet it is to our advantage to complete the cabane diagonal struts before covering. Further the drawings we have are for a hand-started aircraft. Finally, there are no provisions for an electrical system. It is probable that an owner or owners would want electric start and 2 or 3 small circuits such as VHF, Fuel Pump and Strobe Lights or Beacon. Later drawings and photographs contain the details for these items, and the fuselage tabs needed. Therefore the fuselage will be stored for the winter and the focus of work will move to the upper wing. Also we plan to inspect both wings, landing gear and fuselage at one pre-cover inspection by MDRA, when that day arrives.
Bill Evans
(Pitts Project Leader)