and Jim Grizzle, added August 20th, 2004
McGinnis are co-designer/co-builders. The fuse is a Cramer Flat Bat available from
http://www.onlinesports.com/pages/I,CR-001850.html. The knob and the nose are
cut off just past the radius. An HDPE firewall is cut from a WalMart cutting board
to fit inside the bat and pop riveted in place. A Dave Brown 1519 motor mount is
rotated slightly counterclockwise so the muffler will clear the fuse. The battery is
tie-rapped to the inside left of the fuse, opposite the muffler, right behind the firewall
to help in the overall balance. The mini receiver is foam wrapped and tie-rapped to
the bottom of the fuse below the 2" by 5" hole cut in the top of the bat below the
wing. Throttle and elevator mini servos are mounted from the top and the wiring is
run inside the bat. Conventional coroplast tail feathers reinforced with .016
Aluminum 'L' angles are slid into slots cut in the bat and tie-rapped in place. After
determining the balance point for the wing location, 3/16" Carbon Fiber rods are
inserted through the bat for the rubber bands. The OS RNV is modified according to
the instructions provided by Mark LaBoyteaux at http://www.texascombat.com/.
The fuse ready to fly weighs from 21 to 23oz.
We use the 64" SmackII wing with a 4/10" shim under the TE to correct the
incidence. The cores are available from Mike Nemesh at
http://www.mindspring.com/~mnemesh/. The wings are built with the standard
materials, epoxy, bi-di and packing tape. 1/8" FG spars top and bottom with no LE
armor other than bi-di tape. A 5" x 2" hole is cut behind the spar to house the fuel
bladder and is covered on the top by clear plastic cut from a Chicken Finger, (Jim's
favorite meal), box obtained from the Deli section at your local grocery store. 1 ¼"
ailerons and 1 Hitec HS-81MG servo complete the wing. The wing ready to mount
weighs 15 to 17oz.
Parts needed
1 Cramer flat bat
1 laser cut firewall
2 HG51MG Hitec servos
1 Electron 6 Hitech receiver
1 300ma battery
1 battery switch
2 6" servo extensions
5 1/8" long aluminum rivets
6 1/8" short aluminum rivets
1 6" piece Velcro
Zip Ties
1 Dave Brown or Hayes 15/19 motor mount
Control horn and, push rods and connectors
First cut off the front of the bat 1/8" behind the mold line. Cut off the rear of the bat just behind the first ridge on the
handle. These can be cut off with a band saw or radial arm saw but needs to be square. Measure 6-1/2" from the front of
the bat and cut a hole 2" wide x 4" long on the flat side of the bat. This is where you gain access to the inside of the bat
and will be covered by the wing. Cut the elevator servo hole centered just inside the first ridge on the grip of the bat
behind the access hole. Cut the throttle servo hole on the right front of the flat portion bat about 1" from the front edge
and as far to the right as possible, making sure you keep it on the flat area. Next we cut the slots for the vertical and
horizontal stabs. We use a radial arm saw but it can be done with a Dremel also. David made a jig and we cut both slots
for the horizontal with one cut. It is cut on the mold line on each side of the bat. One side has to be trimmed a little to
make it the same length as the other. Raise the cutting depth of the saw and cut the vertical slot in the top center of the
bat the same length as the other slots. Our tail feathers are coro and are mated together with .016 aluminum formed L-
shaped brackets as shown in the above photo. Bend the aluminum to a 90 degree angle and attach to the horizontal and
vertical surfaces with 1/8" rivets. Drill holes and install zip ties to hold it in place. Next we install the battery inside the bat
at the left front.
Leaving enough room for the firewall to be mounted flush to the front we drill four holes large enough for the zip ties, lay
the battery on the outside of the bat and align with the mold line on the side of the bat. Mark your top holes here. Mark
the other two below the battery and drill. It is much easier to mount the batteries before you install the firewall. Slide the
battery inside the bat, run zip ties thru the holes, around the battery and pull tight against the side of the bat.
Now slide the firewall in the front of the bat and square up. I usually glue it with pro bond to keep it from slipping while
drilling. Now drill 5 ea 1/8� holes thru the bat into the firewall and rivet in with 1/8� long aluminum rivets. Put two
on the flat side, one on the bottom and 1 on each side. Install motor mount making sure to put it at an angle that your
muffler will clear the side of the bat. We also drill out the firewall inside the center of the motor mount to save weight. It
is 1" and saves about .3 oz. Now we install the wing hold down dowels. We use 7/32� carbon fiber tube but 1/4
plywood works well also. Wood is heavier and more fragile. Now mount the receiver in the open area of the bat with a
zip tie after wrapping with foam. It is mounted directly against the bottom of the bat. Install your servos and push rods,
hook up the wiring. Mount a Dave Brown 1519 engine mount at an angle for the muffler to clear the fuse, Install engine
and you are finished with the fuse.
We use a 64" Smack wing with 1/8" slots for the fg rods and construction is in the regular manner. We use 1-1/4"ailerons
and attach with bi-di tape. The LE is reinforced with bi-di tape only. No hard leading edge. I hotwire cut a wedge 3/8" at
the thickest point to go under the TE of the wing. Cover with packing tape. Balance should be 2-2/3" to 3" back from
wing leading edge at the root. You should have no problem (with a little experience) make a completed weight just under
40 oz. I have built one at 36.5 oz. with monokote covering.
Our objective was to build an inexpensive, easy to build, easy to fly, easy to launch, light, agile airplane. Although this
took a while as everything was not accomplished in our first few builds. We stuck with the basic design and just tried
improve on it. We are pretty close now. We have worked really close and really well together. These little toy airplanes
have pulled us close as friends.
After all, what can you expect from a couple of newbies?