Next up is to put together a custom battery tray. When performing a glow to electric conversion, often you can use the fuel tank floor for the battery tray. In this case, the floor needed to be lowered about an inch to have enough room for a 6S lipo pack. The stock floor is aligned by sitting in a notch formed by the fuselage doubler. Since I intended to lower the floor, I started by adding some balsa tri-stock to create an upper alignment point. I wanted an upper alignment so that I could easily add some cross-braces (see below) to reinforce the tray from beneath.
I cut a new tray from 1/8″ lite plywood. Unlike the stock tank floor, I cut this to fit the full length between F1 and F3. This will give me plenty of room to adjust the pack fore and aft when balancing. I also wanted to add slots for a Velcro battery strap on either side of the middle of the tray. To cut these slots, I clamped a piece of straight scrap-wood to my drill press table, then drilled a series of holes along the length of the slot. This arrangement allows you to quickly drill a series of holes along a line. The slots are then cleaned up with a popsicle stick with some sandpaper attached.
The tray is then glued in against the tri-stock. Given that a 6S battery can weigh in at over 1-1/2 lbs, I wanted to reinforce the battery tray. I added some 1/4″ x 1/8″ basswood cross braces beneath the tray. This creates a light but rigid platform for the battery. I may add some balsa tri-stock to the corner formed by the fuselage side and the tray floor before is close up the bottom of the fuselage.
I finally got a few days to spend working on the Hog Bipe. I am deviating from the original kit a bit more now. I plan to add a custom scratch-made cowl (more on that coming in a future post), so I cut the fuselage cheeks off at this point.
Another significant modification is to add a custom battery access hatch. I started by cutting the hatch floor from some 1/8 lite ply along with a new F1A and two sets of F2 formers. I used lite ply for the formers in stead of balsa since I felt balsa would end up getting damaged with routine handling of the hatch. One of the F2 formers was glued to the fuselage top at a slight rearward angle, allowing for easy installation and removal of the hatch with no interference. The new F1A was installed square at the front of the new hatch floor. I then positioned the hatch on the fuselage and glued the other F2 to the hatch floor at an angle to match the F2 previously installed to the fuselage top. Stringers were then added.
To secure the hatch, I added a short 1/8″ hardwood dowel to the front and a pair of 1/4″ dia x 1/16″ thick rare earth magnets in the back. A strip of 1/8″ ply was added in front of F2 on the fuselage top for the mating magnets. The magnets were epoxied into 1/4″ dia by 1/16″ deep counter bores made with a forstner bit.
Sheeting proceeded more or less per the kit instructions (sheeting the hatch and the fuselage front separately). I sprayed down the sheeting with a bit of ammonia based window cleaner to soften the wood, then formed it around the fuselage using tape to hold it in place. After letting it dry overnight, I then trimmed it to final shape.
I added some scrap 3/16″ square stringer material to provide something to attach the sheeting bottom to. Instead of CA, I installed each piece with Titebond, holding it in place with pins and tape. I let the glue dry for each piece before moving onto the next. A bit time consuming, but for me, this approach yields the best results.
Sharp eyes will also note I also added a bit of sheeting to the F1 firewall bulkhead so that it would match the battery hatch. I am happy with how the sheeting came out. The hatch fits nice and snug, and all of the seems are nice and tight and will only require a small amount of filler.
Next up is the battery tray, motor mounts, and then the custom cowl.