is the one on the right a down scale of a Jet freak?
if it is, how did it perform? and do you have plans?
Yes it is; you know your gliders! I did these a couple of years ago. I just downscaled the plans (
found here), using as the scale factor the difference in the diameter of a BT-20 (the original Jet Freak's motor tube) and the diameter of a BT-2.5. The scale factor is 0.38179347826086956521739130434783 (
), meaning that the micro version is about 38% of the size of the original plan. I turned the nose cone out of a piece of square basswood stock (the only nose cone that I have ever turned so far).
How did it fly? Well, the nose cone shoulder is actually a short section of BT-2. To provide nose weight, I took a stack of either #2 or #4 steel washers (I can't remember which anymore) and glued it into the shoulder with CA. I arrived at the number by stuffing some washers in and holding them in place with a small ball of tissue, and then giving the glider hand tosses in my living room. Of the three micro gliders that I built, the JF was the easiest to trim balance. I did find that it also needed a little tail weight in the rudder; I used one strip of "match solder" (from
Radio Shack) that I folded around the bottom corner of the rudder. (Before permanently attaching it with CA, I had it taped on with a little strip of cellophane tape for trim testing.) On the top of the wings, running down the center, is a narrow strip of 0.005" steel shim stock cut from a sheet that I obtained from
Small Parts, Inc.
The Micro Jet Freak had nice long, stable glides in many, many hand tosses in my living room. It has made one actual flight, in which it looped off the pad and right into the ground. I think that I may have made a construction error by giving the motor tube a slight up angle; it probably should either be dead level or else have a slight down angle. But I'll also try more test flights with this build.
Anyway, here are the materials and measurements:
Motor tube: 1" (25.5mm) length of FlisKits BT-2.5
Wings: 2-5/16" (59mm)-root edge; 2-17/32" (64mm)-leading edge; 1-3/16" (30mm)-trailing edge. Cut 2 wings from 1/64" (0.4mm) aircraft plywood.
Rudder: 1-3/32" (27.5mm)-root edge; 1-11/32" (34mm)-leading edge; 7/16" (11mm)-top trailing edge; 1/2" (12.5mm)-trailing edge. Cut from 1/64" (0.4mm) aircraft plywood.
Pylon: 1" x 1/8" (25.5mm x 3mm) parallelogram. Cut from 1/16" (1.6mm) basswood.
Nose cone: 3/8" (9.5mm) long by 0.281" (7mm) diameter rounded ogive, turned down from a short length of 3/16" square (5mm²) basswood.
Nose cone shoulder: 5/16" (8mm) length of FlisKits BT-2, glued to the base of the nose cone.
Jet deflector-wing protector: 1-1/4" x 1/2" (32mm x 12.5mm) strip (and then creased in half lengthwise) of 0.005" (0.127mm) thick steel shim stock.
Launch lug: 1/2" (12.5mm) long FlisKits micro launch lug.
Empty weight: Barely perceptible.
Seriously, I don't have a scale sensitive enough to measure the weight; on my gram scale, it barely jiggles the needle.
I am planning to build a BT-3 based version (51% scale) of the plan as well. The fantastically high thrust (relative to its size) of the Micromaxx-II motor might have also contributed to the loop. In that case, a larger, slightly heavier version might boost a little more slowly, which might help the JF stay in the air until motor burn-out.
By the way, this glider was designed to eject its motor, but considering the fact that the empty Micromaxx case is so light, I wonder if it really makes any difference if it keeps the motor. I may try it on a Micromaxx-II NE when I get some.
(The other micro glider, my Micro Invader, also looped into the ground off the pad, but this is a notorious problem with that glider's design. Like the full-sized version, it was a bear to trim balance, too. Not shown in the pictures that I posted is my third micro glider, my Micro AMROCS Wombat, which I constructed out of 1/32" basswood. It was built at the same time as the other two. The Micro Invader and the Micro Wombat both use FlisKits nose cones. The Wombat was the only one of the three that did not loop into the ground when it was launched; it actually transitioned into a flat glide. Unfortunately, I had set up the pad too close to my house, and the Wombat sailed right into the branches of a bush immediately after it began its glide. The full-sized Wombat also happens to be the only glider that I have built so far that actually boosts and glides, so it must be a very forgiving design.
)
MarkII