Parkmaster Pro Profile
Introduction
Thought I would give a small light profile plane a go. Using the Parkmaster Pro as a base to design from and the nice plan and profile pics from the manual....
... I modeled up the panels in sketchup. She is going to be a small bird - just a little under 20 inches wingspan. Planning on a laminated double layer fuse , single layer wing and horizontal stab and light electronics. Goal is to be sub 6 oz. These are the plans - they fit on 7 pages - Yay!
Build Version 1
This ended up pretty badly in that the plane was too small, too heavy and a tad messy. It hasn't been maidened and if I get the parts cut for version 2 before I next get to the field, this one will not be maidened.
Pre-Work
Wanted to try a couple of things before hand. First, does a "glue-spar" (see the FT Viggen build video) add any strength or can extreme packing tape do the job. Second, what adhesive works best for lamination, hot glue, Titan II (a PVA based glue I think) or gorilla glue. I was going to go all nerdy and actually measure things like deflection under load etc. In the end I just selected the best based on what I could feel in the piece.
The test articles were 20 x 3 inch strips of foamboard.
For the glue spar a single layer was score cut length ways, the cut opened to apply glue, then closed and let set. Glues were hot glue, Titan II , and gorilla glue. A sample was also setup with a half-width extreme packing tape strip applied lenghtways to both sides of the foamboard.
Conclusion: Glue spars dont make any difference to the strength of a strip of foamboard, but extreme packing tape strips does help alot.
For the lamination, 2 of the 20 x 3 inch strips were glued face to face. The hot glue was liberally applied in a tight "s" pattern across the piece. The other two were applied and scraped across the piece until an even coating was obtained. The pieces were held under weight until set.
Conclusion: Although a little heavier, the gorilla glue works best as a lamination adhesive. However, it is possible that the Titan II would have fared better if I had worked more quickly with it - I was beginning to set before I completed covering the piece.
Plans
The usual single sheets taped together.
Wing
Part was cut and a BBQ skewer spar was pocketed in the middle of the span, held it with gorilla glue. Extreme packing tape both sides to reinforce. Wing is single layer, flat-plate.
Fuse
Fuse was a double layer laminated with gorilla glue. Prior to lamination two BBQ spars were pocketed into either side. Couldn't decide whether to remove the paper from the inside of each piece or not, so I ended up removing the paper from one side only. Small pieces of painters tape were added to the side that received the glue. These were lifted and small tacks of hot glue added just before making the sandwich. Part was laid flat under weights until set. Rudder is a tape hinge (extreme packing tape captured between the layers before lamination)
Horizontal Stabilizer
Just a small version of the wing really.
Final Parts and Dry Fit
Wing and Horizontal Stabilizer Install
Using a couple of storage containers as supports the stabilizer and wing were both glued in place at the same time. The supports ensured that the fuse, wing, and stabilzer were all square and true.
Weight Check
After the parts were set, a quick check on the weight indicates that were are heading for >8 oz, which is gonna be a little heavy for this bird. The motor being used is the smallest I have and will produce about 12oz thrust on 3S with an 8x6 prop. At this point it was also evident that additional spars were needed for the wing. Two additional spars were added each side.
Component Mounting
A couple of additional foam pieces were added to widen the nose so that a small section of plywood could be glued in place and reinforced with extreme packing tape. With the motor and ESC installed, the 9 gram servos were tacked into position with a small bead of hot glue so that the balance of the plane could be checked. The front servo needed to be installed about 1 inch forward of the original "guestimate" in the plans. The various pockets were cut for the servos and they were hot glued in place. Once everything was in place, she looked a bit of a mess
Final Product
Not pretty and probably won't fly.
Next Steps
As the month progresses, I'll have another go at this. Larger airframe (28-30 inch WS), and probably a KF foil.
Update 23FEB19 - No real update. This one got thrown on the bench while I worked on other stuff. When I last went out flying I thought I would chuck her up to see what would happen but notices that the fuse had developed a slight curve. Not sure if this was because she had a lot of other stuff piled on top over the couple of weeks.
Update 022419 - I used a thin strip of extreme packing tape to pull the fuse straight last night and, seeing as she was built, attempted to maiden her today - which was a disaster - as predicted. Oh well.