Wing Center Section
– The first step is to mark the spar tube over the plan and cut it to length. Also lightly sand any smoke stain off the laser cut parts for a nice appearance. The balsa ribs all gently pressed on the tubes and the ply ribs required minor reaming for final fit. Once the ribs were fit, centered and squared they were clamped and glued together with thin CA as an assembly.
The Trailing Edge is aligned perfectly over the plan. Unlike the other YJ models except the 2M GS the 1.5m is designed with only one TE piece on the bottom instead of two (top and bottom). The TE does not require any shaping. I use weights or a heavy can at the end of the spar tube to keep it centered. The ribs are aligned and glued to the TE first with thick CA. With the ribs pushed flat on the level building board the long ribs are then glued to the spar tube with a drop or two of thin CA.
Once the long ribs are glued the 1.8mm Leading Edge rod is press fit into the ribs. The ribs in the center area are cut back to accommodate the center sheeting. The center ribs will barely touch the LE. Final gluing of the center ribs is completed when the lower center sheet is added. Once the LE is press in place start gluing the LE rod with thin CA insuring the ribs are properly aligned over the build plan. The LE rod aligns the half ribs, first a drop of thin CA at the LE, then a drop or two at the spar tube. Once its all together and removed from the building board inspect the glue joints and add a drop at the spar tube in areas that may not have been reached initially.
The end ribs are set to the 4 degree angle (both mid and center-total 8 degrees) using the angle tool before gluing. Unlike the other YJ models the 1.5M does not have balsa laminated to ply that needs to be sanded.
The upper forward sheeting butts up against the forward spoiler bay support. Install it before the top sheeting. Also the ply cross supports in the center beam must be in place. Drill through the center mounting holes/beam/lower sheeting with a 4mm bit before adding the top sheeting.
Top sheeting in place and rear spoiler bay support.
The center section outer three ribs carry a 5/32 OD aluminum tube for the 1/8″ solid joiner rod. Running a 5/32″ drill bit through the tube holes in the ribs first will make fitting the tubes easy and quick. Once the tubes were cut they were wiped clean with Denatured Alcohol then secured in the ribs with thin CA. Be CAREFUL to identify the 1/8″ rod and 3mm rod or tube that joins the mid to tip. 3mm is only .007″ smaller than 1/8″. 3mm will fit this tube loosely and you need the 1/8″ rod for a good fit.
Wing Mid Panel “B”
Building the Mid Panel has one key item you should be careful not to forget. Washout is built into the wing in this panel by raising the outer end of the Trailing Edge 1/32″. This is accomplished by sanding a shim the length of the TE wide enough to support it, tapered from 1/32″ to zero. Below is the shim I made. It tapers from right to left with the thicker 1/32″ at the outer portion of the TE. It simply slides under the TE to induce a twist.
The ribs are all glued in place in the same manner as the center section. The inner rib B1 is glued at the TE but not at the spar or LE. Final gluing of B1 will be completed when this panel is mated to the center section. This is how you get perfect alignment.
The 1/8″ solid CF joiner rod is cut to length. A 1/8″ drill bit has been run through the ribs in the Mid Panel and the rod is dry fit in place. Its would be easier to fit the joiner holes with the drill before assembling the panel.
The Mid panel is matched to the center section. Rib B1 is now pulled in the place and the alignment is perfect. Now you carefully slide them apart and glue B1 to the spar and LE rod.
Next fit the rear alignment pin. A small left over piece of 1.8mm LE rod works well for the pin. A 2mm bit works fine to drill the holes and leaves a hair of play to make alignment easy. Thick CA works well to secure the pin. I glue them into the center panel.
The easiest way to do this is to drill through one mating rib, then match the panels and use a drill bit through your drilled hole to mark the other mating rib. Then drill the mating rib with the panels separated. The mark is between my finger tips in the photo below.
Tip Panels-Next
The Tip panels are the easiest and quickest. Ribs are fit on the spar tubes and the joiner holes are passed through with a 3mm drill bit. Root rib C1 is not secured to the spar tube and leading edge until its match to the Mid panel “B”. Once mated the joiner and ribs are secured with thin CA.
The tips are matched to the end rib and marked.
Top surface is sanded to match the end rib airfoil.
The lower surface is sanded working from the outside edge until there is a thin edge.
The mating tip edge is sanded to a 4.5 degree angle using the angle tool. The end rib and tip have a thin coat of Titebond “each side”. Pins work well to hold the tip in place while the glue dries.
The wing is now built. It took a few hours two mornings in a row.
Fuselage Pod
The pod goes together quickly and easily. Taking a little time up front will save time later when access will be more difficult after its assembled.
Check F2 former to ensure the PTFE push rod tubing fits through the two hole options. There are upper and lower and the decision which to use depends on the servos you use and how high they are. With HS53’s the top hole works well and routing the push rods/tubes is easily accessably.
Fit F3 and F4 to the boom. I used the same reamer I use to the fit ribs to spar tubes. It only takes a light pass. Since the boom on the 1.5M is straight it can be inserted into the pod after pod assembly.
Take a look at your battery. I this case I want to use the same batteries I use in my 2M. From the previous build I know it fits behind F1 and in front of the servo tray. I wanted to be able to move it forward for balance if needed. The two choice were to remove material from the back of the nose block, or open up F1 so the battery could pass through. I elected to open up F1. This former may come like this in the future.
The 1/16 ply tow hook upper reinforcement is glued in place. The nose block is also laminated together and glued to the front of the pod floor.
The 1/8″ square basswood stringers are cut into 3 pieces each side to run from the back of nose block to former F3. The Stringer is cut to step up over the tow hook support. Later you will see that the tow hook fits between the stringers and they prevent it from twisting.
The 1/64′ ply inner side reinforcements are lightly brushed with Z-Poxy laminating resin. Brush the resin or epoxy on the ply parts in order to avoid applying resin where the lightening holes are to save weight. Match them up, lay a piece of plastic over them and weigh down while the cure.
After a trial dry fit glue was applied to the mating surfaces and the sides clamped in place. I have used wood glue and 30 minute epoxy. Epoxy will provide more working time. 30 minute is fine, 45-60 minute would be great.
The 1/64 ply tow hook reinforcement is glued on the bottom at the tow hook slot. Since the bottom is balsa this helps prevent crushing when you tighten the adjustable tow hook. The slot is positioned so the center is very close to CG.
The wing mounting supports are marked WMF (front) and WMR (rear). The upper is ply and the lower is balsa. The balsa has a hex cut to accept the nylon 4mm wing mounting nut. Once the nuts are pressed in they are secured by wicking thin CA into the balsa and letting it wick in. Then the ply pieces are glued on top the balsa pieces.
I notched the lower forward rear filler so it fits flush with the pod bottom.
The rear filler is shaped to wrap around the boom using a round file.
Rear filler pieces are in place. The excess will be sanded of when shaping the pod. I use the side wheel of bench top sander and roll the pod while shaping.
The pod has now been shaped front and rear. The hatch was cut and sanded to match the pod. A small piece was cut from the front of the hatch and glued to catch the forward hold down.
I have some small magnets I am using for the rear hatch hold down. I cut two small balsa pieces to hold the magnets. The balsa was glued in the pod first, then the magnets were glued in with thick CA. They are spaced down to allow room for the washers which are glued under the hatch.
The photo shows the hatch with the washers and a small piece of 1/64 ply scrap for the hatch hold down. The H Stab and Elevator are shaped and the 1/64 ply reinforcements are glued on. The H Stab has ply top and bottom to prevent damage to the balsa when bolted on. The Fin and Rudder are also assembled.
The Stabilizer Mount has the nylon 3mm nuts installed in SM2. This is glued together bottom to top as shown then the ply end pieces are glued on. The holes in SM3 and SM4 are there to allow space for the mounting bolts should they extend past the nuts. The bottom part SM5 will protrude into the lower half moon of the ply end pieces. The balsa will be filed to match the end pieces and the shape of the boom.
Everything in the kit shown ready to cover.
Wing 69 grams
Fuse and Tail 60 grams
Total 129 grams
There is approximately 10 extra inches of music wire that has not been trimmed yet
