Almost finished!!!! It's Big and Beautiful!!!!
Construction of the AS-K 18
by Jim Ealy, 2006
The laser cut parts are superb, not too
tight of a fit, but laser cut just to hold together until glue
dries. For the record, this is the easiest wing I have ever built -
is too scale AND not over engineered! I used CA glue and 15 minute
epoxy for this kit. I placed plans with wax paper on one of my long
tables. These tables are framed up 2" x 4" with 1 inch plywood 30"
x 108" and 5/8 "homesote" for ease of pinning. I have never felt
that a piece of glass was worth the effort. My 10 year old tables
are still flat and have been used for many excellent flying ships.
Most of you will not have a 1/2 in plate glass top that is also 8
feet long. Also, the pictures are shot with flash and natural
light. I just got a new digital and did not realize that the lens
was fast enough to give pleasing and detailed shots in natural
light. When I did learn this fact - I did not want to rip the wing
apart to retake the shots. The remaining tail feathers and
fuse will all be done in same lighting conditions.
Decide if you are going to build the 2 piece or 4 piece
After making that decision layout the plans with wax paper on
Take the 1/8 by 1/2 spruce spar material and cut to length. If
you need to splice, make sure your diagonal cut is at least 2 and
1/2 times the width. (1/2 x 2 1/2) = 1 1/4 inch long. (Pic #1) I
made the two piece wing, so I cut and glued a full length spar with
1/2 x 1/8 inboard and 3/8 x 1/8 outboard portion.
Then you need to attach a 1/2" by total length piece of 0.007"
carbon strip. This will allow you to also winch launch and do
aerobatics. This was done to both top and bottom spars. Whether it
is best to attach the carbon on the inside of the spars or the
outside of the spars is your choice and who you believe. Some
suggest that carbon on top and bottom of each spar is better. Your
The wing is more accurately built upside down (Pic #2). The full
scale ship has flat tops and up swept bottoms. While this is a much
more difficult process - whether it is worth it, is really up to
you. The ship also has dihedral and that really obscures the issue.
It is almost impossible to tell the correct from the incorrect when
the wing also has dihedral. With the Granau Baby IIb --- no
dihedral, a flat bottom wing appears very different from the full
Full span webs are specified for the wing. It is a matter of
debate, whether to place a rib, then the next web, and the next rib
(Pic #3), etc or to glue all ribs and then add webs. I do both
until I get bored, then I change. The end result is the same, if
both are done carefully.
The plans call for two wings tubes and rods off of the spar (Pic
#4). It turns out that many large GREAT TD ships from the past used
exactly this method. This spar design survived, when other part of
the fuse and wing did not in a successful rekitting.
Place the sheeting over the plans. Make every effort to plot rib
locations on the sheeting, as it will be impossible to see
locations from the plans with the sheeting in place.
Glue carbon/spruce spar in place.
Add ribs and webbing
I decided to use a single wing rod sandwiched between the spars
with vertical webs epoxied in place with 3/32 ply web caps between
I also added a 1/4" by 1/8" spar TE to the balsa sheeting.
Others would suggest that a 1/4 - 1/2 " by 0.004 carbon strip would
be better, sandwiched between the top and bottom sheeting. It
would, but that adds additional cost that some may not want to
endure. Both are probably not needed. However, my TE's get wavy
after several years of flying in humid conditions.
If you build the 4 piece wing you will need to add a wing rod
tube to the inboard and outboard panel at the spar (Pic #6).
- a) The normal way to complete this process is to cut a carbon
or brass tube to total length (2 bays). Cut outside diameter of
tube hole in the end ribs.
- b) Place both inboard and outboard wing panels in place on
- c) Insert wing rod tube in place.
- d) Fit, epoxy, and add webbing below and above the tube.
- e) Epoxy 1/16 ply web caps (top to bottom) on both sides of
wing rod tube.
- f) Use cut-off wheel between ribs 25 and 25a to cut wing rod
tube in half, CAREFULLY! (Pic #6). A 2nd method is to
cut the tubes first, put in place, insert wing rod and then epoxy
tubes in place CAREFULLY!!!. Both methods have disadvantages -
1st methods can nick up ribs, 2nd can glue
rod in place. However, I do glue one end of the rod into place,
keeps from getting lost.
Use a 1/8 carbon rod for an alignment or a 5/32 wooden dowel.
Use a hard balsa block between ribs 24 and 25 and ribs 25a and
Add aileron sub-spars (Pic #7). I increased the aileron sub spar
length by one rib bay in both directions beyond the plans for extra
strength and support (Pic #8).
Glue the 1/8" false leading edge. Splice the false LE in the
same fashion as the spars. Glue in place, and trim to correct
height for total length with razor plane.
Important Note: Use the triangular shaped spruce
spar-splice pieces as jig pieces to lift up the wing tip to build
in the wash-out. Do the same with the aileron outboard end. By
moving these pieces in and out, you can achieve the correct amount
of staggered lift to the TE of the wing to achieve the desired
wash-out. This will be easier to do, if you build the wing in the
flat bottom version. If you build the wing upside down, you will
need to shim up the TE of the entire inboard section and pin down
the wing tip, before you add the bottom sheeting.
Continue adding ribs 26 - 43. Cutting aileron sub ribs and
gluing in place on aileron sheeting.
Trim the aileron sub-spars for airfoil shape guided by the top
surface of ribs.
Glue the remaining TE sheeting in place.
Add the Aileron servo. I chose to attach the push rod inside the
wing (Pic #9).
The spoilers are not difficult. You must however, choose whether
to go with the barn-door or the Shempp-Hirth style (Pic #10). I
decide that two pairs of Multiplex spoilers were too much of an
investment for the first build. In later builds, I will add them to
the top and bottom as per full scale craft. For the first build, I
used the barn-door style (Pic #11) as per plan and on the top only.
These will certainly be effective for the model.
Add long TWISTED spoiler wires though holes provided (Pic #12
and 13). I decided not to use the four wire/one plug version. I
will glue the end plugs together to prevent incorrect orientation
Add top sheeting. Complete the spoiler installation. Trim the LE
of aileron for top hinging. The gap should be at least 3/8" (Pic
#14) at bottom of sub spars. This will allow for about 1 1/2"
aileron and 5/8" down aileron.
Add the balsa LE. Plane and sand to correct shape. Wing will be
covered with white Coverite and trimmed with latex paint.
The Fuselage is even
better engineered than the wings. This is a perfect ship for the
first time "newbie's" scale kit builder. You will
take great pride in the finished project. For those of us who
remember Ambroid fondly – this will be a great joy!!! This is a
combination of sound modern construction with the old "box-loc"
of years past. The parts are cut perfectly with just enough
tightness to ensure staying in place for the time needed to ensure
- Glue the horizontal plate (#11) to formers E and F.
- Glue the two braces (#17) to the plate and former E.
- Brace or clamp to ensure straightness! The straightness of these parts will ensure the straightness of the entire fuse.
- Glue former G to the plate, etc.
- Glue braces (17) to the plate and former G at the same time.
- Again, brace or clamp to ensure trueness.
- Here is where things get interesting... Dry fit ribs 10 and 10a (2) and vertical brace.
- Cut a piece of spar material (1/2 by 3/16 x 51/4)
all fit together and need to be assembled, but not glued together.
When satisfied with the fit and procedure, check again!
- Glue assembled ribs, brace and spar to top of plate.
- Check trueness -- adjust if necessary before glue dries.
- Glue 10b (2) to the vertical brace and plate. Clamp in place.
- Dry fit wheel-well support and keel in place. Mark positions of formers on both pieces,
make sure that it is straight and accurate to the plans. Also make
sure that the formers are still vertical and not bowed/bent. Only
when you are certain that all is as called for on plans --
remove, add glue, and refit. CLAMP to ensure that all stays as
- Add plywood false former ( ). This can be done as the very first step. I just
overlooked/forgot it in my rush to get started!
- Add spruce stringers to both sides of fuse, add forward keel (), add formers:
B,C,and D. I used rubber bands to hold in place. It is best to glue
the stringers to formers E, F, and G. Again decide how you are
going to best do this in the dry state. When you have it aligned,
straight and true -- mark all positions on the keel and stringers.
Again make sure the formers are vertical as per plan and
perpendicular to keel. This is where you "position twice and
- Do not add former A.
- Glue formers B, C, and D in place, rubber band and clamp. Trim stringers to correct
length and glue former A to keel. Make sure it is aligned correctly.
- Your keel should look straight!!!
- Fit top keel (), align and mark positions. Glue in place.
- Clamp all parts in correct alignment.
- Dry fit the other
stringers, be sure to make sure that the formers remain vertical and
the fuse remains straight.
- Glue the stringers
in place, clamp and or use rubber bands to hold in place.
- The plans call for
hard balsa 1/4 x 3/8", I substituted redwood, light and
stronger that hard balsa. You must stop gluing at former B, until
you have added this stringer to both sides. Before dry fitting this
stringer, trim the stringer from former C to former A. When the
glue joints for both stringers have dried, wet the wood, this will
make it easier to force the thick stringers to meet former A.
- Trim and glue the
aft section of the 1/4 x 3/8 stringer in place on both sides of
- Add the remaining
stringers, glue in place ONLY forward of former G. When dry, put
the remaining formers in place. DO NOT GLUE, YET. Align the aft
formers in place. Check to make sure that they are aligned correctly
in the vertical and laterally. After you are sure all is correct --
check with the plan several times. Mark each former's position
on each stringer. Remove formers and glue each carefully in place.
- When dry, add top
and bottom stringer, check alignment. Make sure the aft section is
straight and true. When all is straight, glue the top and bottom
stringers in place.
- When all stringers are in place and the aft section is straight and
true, add and glue the diagonal 1/8" x 1/2" strips.
Wheel Well and Sheeting
- The wheel well is
very solid. The plan shows the two half moon shaped doublers on
the outside of the wheel well sides. They should go on the inside,
so that the 1/4" square spruce
supports will fit without notching as in the picture #19
- I used a brass tube
that fits inside the wheel hub. I then glued a piece of carbon rod
with OD equal to ID of brass tube in the brass tube.
- The wheel well fits
nicely in the former E slot. The plywood support half ring also fits
nicely and provides very good support.
- As is evident in
this photo, I've covered the fuse with 1/64" ply sheeting
instead of 1/16 balsa as per
plan. I wanted the inside of the cockpit to show the ply of the full
scale ship. The 1/64 ply is very strong and provides for more resistance
to puncture. If the plywood is
not important, then go with hard 1/16 balsa sheeting.
- I will glue a
releasable tow hook in front of the wheel well and to the bottom
keel. This two hook can
be used for aero-towing or for winch launching. While the tow
hook is too far
forward for maximum winch launches, it will give reasonable height.
You can always increase the line length.
Picture # 21
- The only way to add
ply or balsa sheeting is to cut and fit, cut and fit. I suggest that
you sand the
edges of the ply skid to the proper angle to make a smooth transition.
I did not, but
will on the second build. You can see from picture #21 and the next
Picture #22 that
formers A, B, and C also need to be sanded to the proper angle.
Picture # 22
- The top keel also
needs to be sanded to the former contour for the best fit of the sheeting.
- Add all of the
sheeting and sand to smooth contour from former A to G. Be sure
to have everything completed, BEFORE completing the sheeting. The
top sheeting needs to be completed in two sections, from former B to
C and from former A to B. The compound bends will not allow one
piece from former A to C. The only sharp transition lines that show
on the full scale are the two below the canopy hinge line.
FIN AND RUDDER
- The fin and rudder is a typical build. I started with the rudder.
- Trim a piece of very hard balsa or spruce with a plane.
- Add triangle gussets to the ribs and then glue rib/gusset
combination to the spar.
Rudder/fin picture #1
- Add TE and block it up with 1/8 pieces
- Add a small piece of balsa at top.
- Add large piece of hard balsa for bottom of rudder.
- Add 1/64 ply
sheeting or 1/16 balsa top and bottom, on both sides
- Sand to shape
- Trim another piece
of very hard balsa or spruce to shape to match the rudder spar.
- I added ribs in
vertical position just as I did with the rudder spar. Add triangular
- Raise the LE with
1/8 strips. Glue LE to ribs and top gusset
- Add sheeting
balsa to both sides. Be sure to have balsa sheeting exceed the fin
spar to provide a hinge gap seal!
- Sand to shape and contour.
- Trim top and
bottom spars of the fin and rudder for brass hinge pins.
- Top hinge is a
single strip of brass drilled for three screws. Two for fin and one
for rudder spar.
- I added a small
piece of brass to the bottom of the fin spar. I then soldered
another piece of brass to the first piece to form a "T" with the
vertical section of the "T" screwed to the rudder spar. I also
clamped the brass strip down with screws.
- If you are going
to use regular hinges, hard balsa spars would be OK. But if you are
going to use this method of hinging, use spruce spars.
Cockpit/Canopy Refit and Fuse Twisting
- My fuse does not
have the twisting, that has been discussed in several chat-rooms, as
I used spruce for ALL longerons. This does make the tail heavier.
But something I can live with. I do not believe that you need to
sheet the aft section. If you used balsa longerons, diagonal
bamboo skewers (horizontal and vertical) can be used in the aft
section to stop the twisting and still maintain the scalloped formers
look with the covering. You could also sheet "just" the fuse
section under the stab, for additional anti-twisting.
The plans have a
significant mistake with the shape of the canopy and frame. HOWEVER,
this can be corrected in about 2 hours of relaxed work, if you have
already completed the fuse according to plans. I had, as per the
building of the fuse section!!! If you have not started, it will
require much less time.
I built the fuse/canopy
as per plans, but I had a funny feeling about the shape since I open
the kit. I could not place the problem, if there was one. The full
scale ship has the front canopy frame, CA, tilted forward, per the
pictures on Ray's website. The plans show the canopy's front
frame vertical. I have about 100 pictures of different ASK-18's
and I still could not "place/see" the mistake on the plans......
Use a Zona saw and
"saw" down through the sheeting. After marking the sheeting with
a pencil, start the cut, 1 inch from the vertical on the top keel.
The cutting should be done slowly and carefully! Cut the top part of
former C from the bottom part. Tilt it forward until it just fits
under the sheeting and the top keel. At one inch, C is just perfect,
the down slop of the keel allows C to once again fit correctly. See
following pictures. LUCK!!!!!!!
Pictures #0a and 0b: Plastic on frame and Correction on plans
Picture #1 Canopy frame vertical and the fuse corrected
If you use the canopy
frame as provided -- you do not have to cut another CA. Picture #2
shows a one inch forward slant.
The stretcher bar in
the front of the canopy frame (picture #2) is useless and ugly. I cut
this out and Ray and I both laminated CA with 0.007 carbon sheet for
strength, as per picture #3 Trim to fit.
- In picture #4, the
finished frame CA is in place. You must glue a 1/4 square spruce
longeron to the bottom of the canopy frame for proper fit and
strength. In the next section I will show you how to "up-scale"
the cockpit with very little effort.
Up-Scale the Cockpit
The cockpit can be
given a full-scale appearance with very little effort!! The
instrument panel provided is un-like any I've seen in an ASK-18. I
copied the instrument panel shown in Ray's website pictures. I
added a floor for the instrument panel, pilot's legs, and stick. I
also used a few bamboo skewers (painted with aluminum paint) to
simulate the tube construction. (pic #1 and
#6) The instrument panel
can be stained with walnut stain with a cloth and by rubbing in
several coats. The back of the canopy frame is not scale, but adds
structure and support to the canopy.
(pic #3) Therefore a few
access panel holes are cut into the former E and canopy EA.
EA is also stained with walnut. The canopy frame is painted
black as per the photos on Rays; website. The seat is visible in pic
#1 & #5
behind the pilot and
#6. The releasable tow hook and
servo are hidden below the seat, made from 1/8 lite ply.
In pic #6,
the seat can be seen, the metal tube structure, and the beginning of
the well for the stick. I will also mount a camera on the canopy
frame, cut in a sliding ventilation window, and a ditty bag. These
extras may take 5 hours total, but they add so much to the overall
Cockpit picture #1
Cockpit picture #2
Cockpit picture #3
Cockpit picture #4
Cockpit picture #5
Cockpit picture #6
Stab and Elevator
- The stab and elevator
are built the same way as the rudder and fin. Glue ribs to hard balsa
spars. Glue the LE and tips to spar and ribs.
- Do the same with the
TE and elevator spar.
- Add the gussets and
elevator tips. Decide how you are going to hinge the elevator. You
may wish to add a few blocks of hard balsa for the hinge points. If
you are planning on using flat blade hinges, the spars are more than
- Shape and sand all
parts to a smooth outline to match the plans. Select light, but
sturdy 1/16 balsa sheeting for the stab. I added a few more hard
balsa and ply pieces to the stab root. I will attach the stab and
elevator permanently. (Epoxy) Add balsa sheet to top and bottom of
the stab and sand to a smooth contour.
- I used a pull/pull
setup for the rudder. I also added bamboo skewers as cross braces and
that stiffen the aft end of the fuse to my liking. I also added a
piece of 1/32 ply under the stab on both sides for stiffness and a
clean exit for the pull/pull cables. I have not decided on a skid,
as per kit and plans, or a wheel as per several full scale ships.
Servos in fuse/wing
nacelle/turtle deck. Front half of fuse/wing nacelle covered and
spruce strips add to aft section of nacelle for ply hatch cover hold
downs. The front half will be covered with 1/64 ply. The 1/4;
inch hole on both sides of the aft - nacelle are for the 1/4;
inch dowel alignment pins attached to wings.
The hole between the
two elevator halves is the slot for the elevator horn.
Sky Bench Aerotech
Ft. Wayne, Indiana 46804