The baggage compartment floor for the RV-3 presents many of the same challenges as did the seat pan ? but in addition to stating out as a fairly plane sheet of metal that has to end up fitting in a curve, it also has elements of taper and a curve across the airplane (form side to side) that has to be contended with. The piece of raw stock that you get to fabricate the floor with is a bit deceptive ? it?s shape invites you to find a centerline from the ?bottom? edge and measure from there- but if you do this, you?re going to run out of material before you reach the other end. A paper template is definitely an important tool in figuring out how to cut this piece out.
I started out with a ream of heavy ?card stock? paper that I originally bought for making checklist cue cards. I laid out enough of these to carpet the projected size of the compartment floor and taped them together with wide masking tape, making myself a single big sheet of stock. I then measured the length of the compartment, from bulkhead to bulkhead, as well as the width of the ?overlap? onto the F-305 (in front), and F-306 (in back). I transferred these to the sheet and cut it to length, plus the tabs. Marking a centerline on the sheet, as well as on the two bulkheads, was the next important step. This served as a reference for putting it in and removing it repeatedly.
I had previously mounted the elevator bell crank supports to the F-306 using clecos. I now used those clecos to give me good positioning for the template sheet by piercing the sheet with the clecos, and sandwiching the paper between the angles and the bulkhead. I did the same thing up front with the clecos holding the seat pan to the F-305. With the raw template stock held fore and aft, it was a simple matter to press it on each side where it meets the fuselage stringer. Remember to make sure that it stays tight to the baggage floor ribs as well. Creasing the card stock with my fingernail was the easiest way to make sure that I left a mark I could use to find the edge. The cut-outs for the flap actuator were made from drawing measurements (which actually sem to be correct!)
From this point, I removed the creased template and traced over the creases with a pen and straight edge. I then cut it out and laid it on the aluminum stock, finally figuring out that you have to place it somewhat diagonally to make it fit. Verily ? Van DOES give you enough aluminum to make the part!
The only thing special about cutting out and shaping the part was putting in the creases on both sides where it ?breaks? to go on to the fuselage stringers. It pays to have a homebuilding neighbor with a long sheet-metal break?.
DON?T make the bends based purely on your paper template ? wait until you fit the aluminum and mark it precisely ? paper changes dimension with humidity ? and in Houston, we have LOTS of humidity!
Drilling the floor to the ribs is very similar to installing the seat pan ? very careful measurement to establish a baseline for the center of each baggage floor rib, then drilling the floor, and finally drilling it to the ribs. I like to drill with a #40 first, just in case I have to make little ?adjustments? before upsizing to the eventual #30?s for the final pop rivets. Since the sides of the floor actually curve on their way to the stringers on the fuselage sides, I drilled them firmly to the floor ribs first to establish the ?flat portion, then did the sides. Making and installing the stiffeners on the floor between the two floor ribs was straightforward, if a little tedious (had to bring out the C-Frame and back-riveting plate ? hadn?t used those for a little while!).
I am sure that the flap actuator ?dog-houses? will be fun to fabricate, what with the slight curve and all. I think I?ll go work on the forward seat ?steps? and stick mixer close-outs, and let the dust settle in back for awhile....
(And while I have been building floors, Louise has made a really nice seat back...I'm sure she'll write it up, eventually....I hope so - I want to learn how she made the fiberglass top fit so well!)
Paul
I started out with a ream of heavy ?card stock? paper that I originally bought for making checklist cue cards. I laid out enough of these to carpet the projected size of the compartment floor and taped them together with wide masking tape, making myself a single big sheet of stock. I then measured the length of the compartment, from bulkhead to bulkhead, as well as the width of the ?overlap? onto the F-305 (in front), and F-306 (in back). I transferred these to the sheet and cut it to length, plus the tabs. Marking a centerline on the sheet, as well as on the two bulkheads, was the next important step. This served as a reference for putting it in and removing it repeatedly.
I had previously mounted the elevator bell crank supports to the F-306 using clecos. I now used those clecos to give me good positioning for the template sheet by piercing the sheet with the clecos, and sandwiching the paper between the angles and the bulkhead. I did the same thing up front with the clecos holding the seat pan to the F-305. With the raw template stock held fore and aft, it was a simple matter to press it on each side where it meets the fuselage stringer. Remember to make sure that it stays tight to the baggage floor ribs as well. Creasing the card stock with my fingernail was the easiest way to make sure that I left a mark I could use to find the edge. The cut-outs for the flap actuator were made from drawing measurements (which actually sem to be correct!)
From this point, I removed the creased template and traced over the creases with a pen and straight edge. I then cut it out and laid it on the aluminum stock, finally figuring out that you have to place it somewhat diagonally to make it fit. Verily ? Van DOES give you enough aluminum to make the part!
The only thing special about cutting out and shaping the part was putting in the creases on both sides where it ?breaks? to go on to the fuselage stringers. It pays to have a homebuilding neighbor with a long sheet-metal break?.
DON?T make the bends based purely on your paper template ? wait until you fit the aluminum and mark it precisely ? paper changes dimension with humidity ? and in Houston, we have LOTS of humidity!
Drilling the floor to the ribs is very similar to installing the seat pan ? very careful measurement to establish a baseline for the center of each baggage floor rib, then drilling the floor, and finally drilling it to the ribs. I like to drill with a #40 first, just in case I have to make little ?adjustments? before upsizing to the eventual #30?s for the final pop rivets. Since the sides of the floor actually curve on their way to the stringers on the fuselage sides, I drilled them firmly to the floor ribs first to establish the ?flat portion, then did the sides. Making and installing the stiffeners on the floor between the two floor ribs was straightforward, if a little tedious (had to bring out the C-Frame and back-riveting plate ? hadn?t used those for a little while!).
I am sure that the flap actuator ?dog-houses? will be fun to fabricate, what with the slight curve and all. I think I?ll go work on the forward seat ?steps? and stick mixer close-outs, and let the dust settle in back for awhile....
(And while I have been building floors, Louise has made a really nice seat back...I'm sure she'll write it up, eventually....I hope so - I want to learn how she made the fiberglass top fit so well!)
Paul
