Biplane (TIG/AWJ) Practice Part

Quick Links

1. Introduction

2. AWJ

3. TIG Welding

4. Source

Introduction [RETURN TO TOP]

This document is intended to train TAs on how to TIG weld and use the lab’s Flow Mach2 Abrasive Water Jet cutting machine.

AWJ [RETURN TO TOP]

1. Follow the [LINK TO ZIP FILE] to download the part, assembly, and .dxf files

2. Copy the .dxf files to a jump drive

3. Obtain a piece of 16 GA steel sheetmetal that is at least 7” by 10” to cut the parts from on the waterjet

4. Follow the AWJ Guideline to cut out the parts

a. Ensure you are cutting the proper quantity of each part in FlowNEST

b. Edges will be sharp and need deburring

TIG Welding [RETURN TO TOP]

1. There are four identical body pieces for the plane fuselage. Take two pieces and lay one flat and the other vertical, placing the long edges together (both pieces of metal need to be touching the table). Tack weld the inside corner of the front end of the plane first and then the inside corner of the back end. Then, tack weld the inside corner in the center of the seam.

2. Use the square front piece (the nosepiece of the plane) for alignment to make sure the angles of the welded pieces are square. Bend body pieces as necessary.

3. Add your third body piece. Tack weld it as you did the first two pieces.

4. Take the fourth body piece and lay it on the table. Then take the three pieces already welded and place it on top of that piece with the open side down. Proceed to tack weld both front corners, both rear corners and middle corners (in that sequence).

5. Make 12 welds to hold the fuselage together. Care must be taken to weld in a sequence that will avoid warpage. We suggest making ˝" long corner welds in the following order: (1) top front right, (2) bottom rear left, (3) top middle left, (4) top rear right, (5) front bottom left, and so on until all 12 welds are complete. The welds on the top middle should start 4" from the front of the plane while the bottom middle welds should start 5" from the front of the plane and go ˝" toward the rear. Once these welds have been completed, your fuselage should be in place.

6. Mount the propeller onto the 6-32 fastener and assemble two nuts behind it. Be sure to leave space for the propeller to move freely.

7. Add another nut on the opposite side of the nose plate, tighten the nuts on both sides and again check that the propeller spins freely. Lastly, tack weld the single nut you placed on the backside opposite from the prop to the square nosepiece.

8. Place the nosepiece at the front of the fuselage assembly and tack weld all four corners. Next, weld the four sides. Start with welding the opposite sides to minimize distortion. Let it cool completely between each weld pass.

9. Your completed fuselage, nose and propeller assembly should look similar to what is pictured.

10. At this point, take a steel wire brush, which has been used only on steel and clean all of your welds.

11. Use the drawing template to locate positions for struts, which need to be center punched and drilled before you can go any further. Center punch (as shown) so when you remove the blueprint template, there is a mark to show you where to drill.

12. Using the 1/8" drill bit, carefully drill approximately 1/3 of the way through the thickness of the wing at the center-punched locations. This will enable you to countersink the struts. Repeat this procedure on the opposite side of the second wing. Check to be sure that you are countersinking the top surface of the bottom wing and the bottom surface of the upper wing.

13. Position the bottom wing on the table with the countersinks facing down and place the fuselage on top. Center the fuselage on the wing from left to right. Be sure the distance from the front edge of the plane wing to the nose is correct. Before welding, make sure that everything is properly in place and then tack weld the four corners together. Use fillet welds (full length) to attach the wing to the fuselage. A heat sink is recommended, however, if warpage does occur, bend the wing to make sure it is flat before going to the next step. Be careful not to overweld, keep the weld as small as possible.

14. Tack weld the four 1/8” steel filler rod struts (cut 1.75” inch) into countersunk holes on the upper wing. Be sure to add the diagonal strut to each side of the wing (see photo for proper placement).

15. Now let's move to the pilot's cockpit windshield. Lay the windshield piece flat and tack weld the two triangular sidepieces to the rectangular windshield pieces along the corner edges. If you feel comfortable welding full seams, go ahead and do so. If not, tacks will suffice. Next, prepare to weld the windshield assembly to the fuselage. To do this, center the front of the windshield the proper distance from the front of the plane. Tack weld the windshield to the fuselage on all sides. For a more attractive appearance, weld the full length of all three seams.

16. Tack the vertical stabilizer (top rudder wing) perpendicular to the fuselage at the back edge of the plane. Then tack the left and right horizontal stabilizers (tail wings) to each side of the fuselage. Check alignment and weld the full length of all seams. Allow each weld to cool completely before going on to the next weld.

17. Attach the upper wing to the plane body, like the lower wing. Place the struts in countersunk holes on the lower wings. Tack weld all struts into place. The diagonal struts are unnecessary for this design but feel free to include them if you would like to.

18. Grind flush the ends of the two carriage bolts. Then, weld the two carriage bolts together, being sure to use filler metal. Since most bolts are cadmium plated, allow for proper ventilation for this particular weld or remove the plating prior to welding.

19. Take an 1/8" diameter piece of steel filler rod material used for the struts and bend it into a V (as shown). Weld the two ends just inside the bolt heads on your landing gear assembly.

20. Weld the bottom V to the bottom of the plane. Center your landing gear at the front edge of the bottom wing. Be sure to add adequate filler metal to provide stability for the landing gear.

21. Tack one of the nuts vertically to the bottom rear of the plane to create the rear landing gear.

22. This step is unnecessary for this design but feel free to do it if you would like to. Cut two, struts to the proper length. Place the plane upside down. Center the strut from the side of the windshield assembly to the top wing at an angle and then weld it in place on the bottom of the top wing.

23. Turn the plane right side up and then weld the struts to the sides of the windshield.

24. Weld the back piece to the opening in the tail section of the fuselage.

Source: [RETURN TO TOP]

1. https://www.lincolnelectric.com/en-us/support/welding-projects/Pages/biplane-detail.aspx