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Archive for June, 2011
Posted by A Useless Geek | Jun 05, 2011 @ 10:18 AM | 10,374 Views
This thread may get a lot of traffic, or none. Who knows? I'll keep updating as I get more photos made of assemblies on which I'm working.

To start with, let's take a look at how I build wing assemblies for the Skinny Boy, Eluder, Longhorn, Lunatic, etc. These are flat pan wings with a dihedral in the middle. The wing roots are cut at an angle so that they meet in a vertical line when the halves are put together. The underside of the assembly gets support from balsa trailing edge wedges cut down to size. After the wedges are put in place the entire underside of the wing root is sanded flat to meet with the flat top of the airframe.

Put the wings top down on a flat surface, then use blue tape down the centerline to hold the assembly together. Flip the wing over and apply puffed up Gorilla Glue to the seam. Weigh down one wing and prop the other one and the correct angle. Prevent the GG from puffing up too much on the top side by applying blue painter's tape. (The cat isn't necessary, but may help relieve tension.) The extra GG puff on the top side of the wing supports the wing during high G maneuvering.

Balsa trailing edge wedges are available at the LHS in long strips. Use a slitter to cut them down to size. You only need enough width to make contact with the top of the airframe, typically 10-16mm wide depending on what you are using. Glue the wedges along the underside of the center seam. The thin edge goes toward the center. The idea is to make a flat surface so that you can glue the wing to the airframe without gaps.

After the glue is cured you can sand the underside of the wing root to get a completely flat surface that can then be glued to the top of the airframe. You gots a basic airplane!
Posted by A Useless Geek | Jun 03, 2011 @ 02:25 PM | 10,089 Views
So, I've sorta fallen down on the really fast park jets the last year or so. The indoor/outdoor sport planes have been so much phun that I've ignored the realm of fast park jets almost completely. A couple of my fast projects are coming back to life now that I have everything (except batteries) to finish them.

I considered doing the Multiplex Blue Shark TwinJet first, since it already has servos mounted and such, but I know how much effort will go into getting the motors aligned on that beast. Instead I'll do the Electrifly Firebat first because it's a little simpler and has some features I want to mess with anyway.

My plan is to enhance the maneuverability with my own stiff balsa elevons, separately-controlled anhedral canards, and linked rudders. Needless to say it will be brushless and carbon fiber supported. I'm not going to go nuts with power; I figure 500 watts or so ought to get it moving pretty good. Maybe a little more.

The naked airframe as shown is at 193 grams, so it won't be a lightweight. (By comparison, a good Longhorn is 180 grams all up.) I'm not really worried about weight at this point because I know I can get it to fly fine with the amount of power I have in the motor box. I am thinking I can get this planes put together at 500 grams or maybe a shade less. And that's with an 80 gram motor, so it ought to scoot pretty good.

Stay tuned as this one comes together.

Later:

Okay, so I decided to try something a little less expensive and maybe...Continue Reading