Workshop

11/9/11

The planning for the build began today as there is a deadline on this plane. A list of required parts was developed and communicated so that we can get the needed stuff on order.

This plane will have 2 aileron servos -- 2 flap servos - 2 elevator servos - one rudder servo - the throttle will be hooked to the ESC on the Hacker motor. It will have a light system that will be operated from the transmitter. The equipment will be a 9 channel JR driven by a 12X transmitter

After the planning was done, the equipment board was first on the list. Hard mounts were hysoled into the bottom of the fuse and the board was made to fit the equipment. The board will hold the main batteries with plugs to check the voltage and the receiver.

 

The wings use servos for the flaps and the ailerons and the hatches were pre-cut. In order to mount the hatches back in place, I glued 1/4 ply strips under the edge of the hatch hole. The strips will hold the blind nuts on the corners of the hatches.

The stab will have servos for each elevator and so the hatches were cut and lined with ply as above. The interior of the stab is hollow so the photo below shows the board that will be glued into the stab and will hold the servo. This was done on both sides of the stab.

Next the elevator hinges were marked and cuts were made in the leading edge of the elevators to accommodate the hinge movement. The hinges were drilled on both sides and the elevators trial fit into position. The plane will be painted before the final hinging takes place. The elevators and stabs were then set aside awaiting the arrival of the servos.

11/10/11

The session began with the rudder drive system. The rudder servo has to drive the rudder and the tail wheel. Since there is an opening under the stab in the aft portion of the fuse, A board was made to hold a servo. The servo will drive the rudder and that control horn will drive the tail wheel with a pull / pull system. The board was then set aside awaiting the servos.

 

Next was the assembly of the wings and the stab. They needed to be assembled and then measured to be sure they were straight .

The stab was assembled without a problem and they the wings were assembled. The wing roots are positioned with two small rods and the struts put the wings in position. Once assembled, the plane was blocked up so that it would not move and could be measured.

The shot below shows the blocking operation and the level center section of the wing. The stab showed the same level reading and that indicates the fuse was correct in the left to right direction.

The wings, however showed 2.5 degrees dihedral in the right wing and a minus one degree in the left. This was a problem that had to be addressed before continuing with the build. The wing roots were slightly inconsistent, but they were not far enough off to cause this large problem in the wings. The struts were not the same and that required some time to correct. I changed the struts to allow for the difference in the wings and they ended up the same.

Above you can see the plane assembled and blocked in a stable position. The wings and stab were level left to right and next I checked to see what the incidences were. The wing incidence was measured and taken to be zero for purposes of measuring the plane. There were no plans or instructions so this is an exercise of discovery.

The stab was found to have an incidence of minus two degrees and this is not unusual for cargo planes. The leading edge of the stab is down and that will make the nose come up in flight. This will help lift the plane from the runway and might cause some down trim in flight. The stab should work in this configuration. I documented the position of the wings and stab for future use.

Tramble is a measure of straightness for the wings and stab. The condition measures if one wing tip is ahead of the other and the tramble must be eliminated in the wings and stab. The stab showed no tramble but the wings needed correction. The wing roots were changed to make the tips the same and this was recorded for use later on.

Next I began to work on the problem of the motor box. The problem is that there is no motor box and no structure in the nose at all. From the leading edge of the wing ahead to the front of the cowl there is nothing but fiberglass skin. There will be a large Hacker electric motor and batteries in the nose of this plane and a motor box has to be designed and attached to the fuse structure so that it will support the forces of this large and powerful motor.

I began with the plane blocked in level position. Level means the center line of the air foil of the wings was level. I then struck the center line of the plan on the building board below the plane and made a board that was perpendicular to the level line ( this will produce no down thrust in the engine) The board was placed up close to the front of the cowl and a line made on the building board to indicate the position of the front of the cowl.

Lines were drawn on the front board to show the center of the cowl, which is the center of the propeller shaft.

On the building board, I drew the cowl line and then moved aft on the center line to allow for the length of the Hacker motor. This was the position of the firewall, which I designed and attached to the board. In the shot below you can see the firewall in the proper position with the cowl removed. I knew the firewall was in the correct position for no down thrust, but it might have some right or left thrust.

Below, you can see that I attached an 8' straight edge to the front board that was centered exactly on the center line of the plane. I used a string from the top of the rudder to the tips of the straight edge to be sure there was no left to right thrust problem.

The firewall was then in position with no down thrust and no right thrust. It was located the correct distance from the end of the cowl and now the design of the motor box could begin.

11/11/11

Veterans day ------ Thank you to all of you that did your duty.

The work on the motor box continued by taking measurements from the fire wall to the structure around the wing saddle. The motor box sides were cut in the rough and then refined to fit in the maze of parts that were in the cowl and the front of the plane. You can see below that the sides were straight as they came out of the front of the plane, but some shape was needed inside the fuse.

The batteries will likely be mounted under the motor box, so some allowances had to be made. After lots of fitting and recutting, the motor box was glued up with several formers to begin to add rigidity to the structure. The glue was allowed to dry

The clamps were removed and the box was test fit into the fuse. The shape was adjusted to bring the fire wall to the proper position.

The back of the motor box is shown below. I made the crossbeam that fit over the sides of the motor box to tie it to the sides of the fuse. This will secure the back of the motor box and prevent it from moving around under load. I did not glue any of this in the plane as yet.

With the back of the motor box secured in position, the front was still loose to move around under the load of the motor.

I cut and fit braces from the dash former to the motor box and made gussets that ran forward as far as I could manage. These supports will help stabilize the front structure.

After some additional part cutting, the box was ready to put into the fuse. Below is a shot of the parts before assembly.

The motor box was then put into the fuse and all the lines checked to be sure it was in the proper position. The front board was supporting the front of the motor box. The rear support (shown above) was then epoxied in place and checked for proper position. There is a former in the fuse just ahead of the dash area and the motor box was glued to that former. The gussets were then glued in position from the forward former facing ahead and reinforcing the box against movement left or right.

Additional parts were then glued in place to stabilize the motor box and all the intersections with the fiberglass were reinforced with hysol.

The cowl was test fit on the plane and the distance from the fire wall to the front of the cowl was checked. Everything looked good for the cowl so final checks were made to measure right thrust ( measured at Right .3 degrees) and down thrust ( measured at 0 degrees) After the first flight we can change the thrust as we see fit.

11/13/11

The rudder was hinged using the same process as the stab and movement was checked. The rudder hinges will be glued in place after paint is done.

11/15/11

Servos arrived in the shop and the installation began with the set up of the servos with the equipment board. The servos were set up and arms set in place with the equipment energized so the true centers could be seen. The transmitter was programmed with the correct direction of throw and all the servos were checked to be sure they functioned properly.

The wing servos were then wired to fit in the bays. Having plugs in the wings is a risk and so all the wires were soldered to make the correct length without plugs to fail. The servos were then mounted in the bays in the wing first. Once they were mounted, the operational directions were confirmed.

Next the hatches were bolted on using button head screws and blind nuts to be sure they would stay in place.

11/16/11

Next the stab was fitted for the servos and the structure was glued in place. The servos were mounted to a frame and then Hysol was used to glue the frame in place. Rails were glued to the frame to stabilize the servo and to give a method of mounting the hatches.

The servos were final tested and the hatches were bolted in place.

The wing tips were then glued in place with Hysol and allowed to dry.

11/21/11

The motor arrived and so the next part of the build could be done. It is a Hacker A100-8 and it has a six bolt hub. The fire wall was designed for this motor so the back plate was removed from the motor and mounted to the plane. This motor produces as much power as a 100 CC gas motor so it needed to be mounted firmly to the plane. The mounting system requires 6MM bolts driven from the back of the fire wall and that was accomplished.

The cowl was then test fit to confirm the correct placement of the structure. . This was checked and adjusted to fit properly.

 

The speed control was mounted on the bottom of the motor box so that it would get some air in flight. The motor box was modified to allow clearance with the cowl and for the air to flow. The connections to the motor were made and leads run to the receiver and to a safety switch to be placed in the plane.

The batteries were not delivered with the motor, so I made a package of weight that was the same as the batteries and used that for CG analysis. I assembled the plane and checked the CG. First measurement the plane was very nose heavy with the 6.4 lbs of batteries all the way forward in the motor box. I repositioned the batteries to give a good CG ( 33% of the wing cord).

 

With this information, I added the rest of the structure to the nose and mounted the spinner back on the motor, as shown above.

Next was the operation of mounting the cowl to the plane. I added 1/4" ply strips in the area where the mounts were needed and that will hold the 6-32 blind nuts and button head screws needed to hold this large cowl in place. As shown below, the spinner back was the reference and the cowl was moved to line up with the outer surface of the spinner back. The full scale plane was checked to be sure this was authentic.

Once the cowl was in position, I mounted one bolt in the rear of the cowl and checked the cowl for position. This is a time consuming process and is the only way to ensure the position will be just right. I might have a little OCD here, but it came out looking very nice.

With these large steps complete I began on the list of small things that must be done before paint can be applied to the plane.

Control horns were glued in the flight surfaces with Hysol

The top hatch had rails added to allow it to be mounted to the plane.

11/22/11

Final items were completed and the plane was sent out for paint. I expect to see it back in the shop on11/28

1/30 through 2/2/12

The plane returned to the shop after paint and we needed to finish the plane to a weekend deadline. Work began immediately with the reassembly of the motor and the speed control.

The wings received the aileron and flap hinges and they were lined up and centered. The links were then made and the servo action was lined up.

The customer uses a JR 12x transmitter and so I opened a new model in the transmitter and did the basic setup for ailerons, elevators and flaps. The surfaces were then checked.

The elevators were done in the same way and the servos tested.

The vertical stabilizer was discovered to have a broken post that supports and holds it in position. This is a serious flaw in the construction of the plane as the post is a long thin piece of balsa and the grain is horizontal instead of vertical. This allowed the post to break just above the aluminum support.

In order to repair this problem, I cut a hatch in the bottom of the plane under the post and cut a ply post to glue to the front side of the broken part.

 

I then epoxied the new post in place with clamps at the bottom and screws into the new post on the upper end. I let the epoxy set up and removed the clamps and screws.

The repair looked good so I added structure to the hatch area and glued it back in place.

 

The tail wheel had a pull pull system tot he rudder hour and that was made and installed.

The motor was reinstalled and the cowl was fitted with the jet exhaust that was scale for the plane. All the other items were put on the plane including windows and the fuse was done.

The main batteries were set in place and the equipment board was bolted back in and hooked up. All the systems were tested and adjusted to the 12x transmitter.

The light system was installed and the wires run to the equipment board

 

The CG was confirmed and the documentation was put in a book for the customer.