As the latest version of the Phlatscript becomes available I've volunteered to be a part of the beta testing process. As part of that I've chosen to draw up plans for a BF-109E. I plan to build this German foam fighter with colors from the Battle of Britton. As this point in the build it is all preliminary work, however I would like to attempt to follow most of the original panel lines as part of it's construction. This hopefully will limit the need for fiberglass and help in a quick build.
Here is the basic Sketchup work drawn from a set of tiff images found on the net. The plans have been challenging to work from due to poor percision details and I had to draw the fuselage twice to get it looking correct.
At this stage I would estimate I am about 40% complete with the modeling of this 109E. The new Sketchup Phlatscript is amazing. Sometimes when complicated parts are unfolded they tend not to be planer. The new phlatscript allows the objects not only to become flat along the X Y, but also creates a face, even with the most complex of parts.
The true test of the Phlatscript is yet to come, but I expect it will not leave anyone disapointed for buiding models out of foam!
I've learned in modeling that inside the computer parts make perfect sense, but when you have a table full blue foam of parts things can get confusing! I've come up with the arrow head and diamond system to aid in assembly. Arrow heads always point upwards or forward, and diamonds point back or down. The Phlatprinter will cut these into the parts, and the reference aids in both finding the center of the part as well as finding what way is up.
Gasmasher of the Phlatforum worked through a lot of bug reports in a very short amount of time. He was very dedicated to this script, and from my point of view, he couldn't have spent any time on anything else!
Needless to say all his hard work paid off, and I was able to begin cutting parts in a manner much faster then before. I really want to thank him for his hard work, I wonder if he has room for one of these monsters?
I'm going to come out and say it right now, at this scale, this is the most complicated build I have done so far. It has been very challanging to build the wing in this manner.
This going to take a huge canopy mold!
The tail was cut out of 1/2 inch Owens Corning, (Toledo built!), foam, which actually measures 9/16. Advanced sanding was needed to shape the airfoil, and the black and decker mouse worked perfectly.
After some of the other planes I've built I've found that mounting the servos directly on the control surfaces has some rather large disadvantages. The 1:1 mechanical advantage ratio has caused others problems with flutter and poor control authority. My problem has been with servo failure. This could be related to a flutter problem, although I've never actually heard a buzz while in flight coming from the tail. Admittedly, the noise could be masked by the motor. Either way, if you have a servo failure and the servo is buried in the wing, good luck replacing it. Too much work goes into these airframes to have to play surgeon to get to the problem.
Now-a-days I mount the servos further forward, in a more replaceable setting. (But you still don't see me using screws!) One day I will learn...
Here shows the movement I'm able to obtain with the current servo setting. Notice the pin joints used in the tail section, instead of the piano style type. Also take note of the center of rotation and how it's offset into the control surface. This allows for a smaller gap at the joint.
Other parts are cut as spaced on the Phlatprinter. The foam template makes mounting accurate and easy. All that's left is to sand and shape.
The above shows the styrene vacuum formed spinner, and the PET-G clear back plate it is glued to. This turned out much better then I expected, and it actually snaps into place. I still feel a bit of glue is required though.
It turns out that I had problems with the wing on this 109. While most would attribute the terrible tip stall to the design, I would like to say that I know better. The tip stall was attributed to the designer, me. As hard as I tried on this thin wing, I had a very difficult time in getting it to be symmetrical. The result was a very nasty tip stall and a huge aileron differential to keep it in level flight. For the scale this was unacceptable. I had to remake the wing. So the squeeze was put on and it turns out that the Phlatprinter will cut 1/4 inch MDF, the same material it's actually made out of...
You are looking at the first set of hot wire templates cut on the Phlatprinter. Made out of 1/4 MDF wood, they work incredible! And the wings that hot wire templates produce no longer have a tendency to tip stall.
Unfortunately I had more problems with this 109 as well. The wimpy original motor mount allowed for extreme vibrations at high RPMs. The result was the entire nose ripping away in flight! A real disaster and spectacular crash. I would have wrote off a lesser model. But the lesson is foam repairs exceptionally well. And with a CNC platform to recut required parts, necessary repairs were made in less then an hours times.
When the nose tore away, the propeller really chopped up the wing. With a sharp knife and some sanding a block was cut and I filled the wing to match.
The motor mount was beefed up with 9/16 foam and the weak joints were fiberglassed.
I'm happy to report that this 109 is one of the best flyers I've had to date. It has an incredible rate of climb and an excellent glide ratio.
Please check out the gallery for more pictures.
DIFFICULTY: Moderate - due to number of fuselage parts, I recommend sanding each section to ensure alignment.
SCALE: 1/7th approx 55 inch wingspan.
PLANS BY: Erik