Build/Repair Article

Oct 30, 2008

The wings were removed and set aside as they are done. With the struts and wiresin place, each pair of upper and lower wings stay attached to each other and can be stacked easily.

The electronics were next and all the gear is accessible from the three hatches on the bottom of the plane. The servos were mounted for the elevators and the rudder while the throttle servo was placed earlier. There are 2 switches as there are redundant batteries in all the planes I build. There is a third switch to cut off the ignition and all 3 were placed in the floor of the cockpit. The floor was made and then all the switches were mounted and set up to be reached from above. The cockpit floor is removable in case the switches would need service. Batteries were mounted on the fire wall to help with the tail heavy problem all of these planes have. The receiver was wired, padded and mounted under the plate for the fuel tank. All wires were secured from vibration and the hatches were put in place.

Next the landing gear was mounted and checked for alignment. George will add the wheels and the torsion system.

The cowl was mounted and checked for alignment.

The cockpit area was originally fitted with a lamination that make it wood grained and this feature needed to be restored to the plane. The veneer material was 1/64" thick and it was carefully cut to fit the area and the hole for the cockpit was roughed in. Once the material fit properly, it was glued in place using white glue.

The tail skid was removed from the plane and it was time to put it back in place. This skid works just as the full scale one did. It torsions as the tail skid hits the ground and I designed a simple method of making this work. There is a post in the rearmost part of the fuse and the post was cut after the cash. The part of the post that was glued in the plane was not going to be removed without doing damage to the structure, so I reinforced the post and center drilled it for a carbon fiber rod. The rod was then deposited into the block and allowed to dry. The post was then drilled and epoxied in place. This allows the post to withstand a considerable force on landing and the skid portion is then rubber banded to a post that is mounted deep in the fuse. The rubber band supplies the force to cushion the skid when it has force on it.

The rudder was covered with a different covering and George wanted to correct that difference with material he brought yesterday. I stripped the rudder and recovered it and remounted it on the plane

The final step was to review the check sheet to be sure all the agreed repairs were made. The plane was then set aside and all the other parts and supplies boxed up for delivery to the customer. There are considerable steps left to get the plane ready to fly and George will complete them and the first flight will happed in the next 2 weeks.

 

This concludes the repair and rebuild project

Oct 29, 2008

The work continued today with the construction of all of the wing wires. There are 4 on each side and while the wings were blocked in the proper position, the wires must be made and set to the proper length. With the help of George, we got all the wires made and in place

The ailerons have a strut that drives the upper aileron from the lower. I completed these struts and adjusted them.

George and I met on the remaining list of items to finish the plane and we now understand what it will take to get it done.

 

Oct 25 - 28, 2008

The In the last few days I have completed all the covering on the plane and it came out very well. The fuse is done covering and all the control wires are in place with the stab and rudder section bolted on and surfaces operating very nicely.

I then moved on the the motor and bolted the engine in place with 2 degrees of right thrust and 2 degrees of down thrust. it is in final position pending the fitting of the large cowl. The gas tank was mounted and all the lines run in the plane. The tank mount is set up to easily remove the tank through the hatches in the bottom of the plane.

The throttle servo was mounted and the linkage was made to give full throttle control and not interfere with the other systems in the plane.

The landing gear has a wire frame and a wood structure that was badly damaged in the crash. The plates at the bottom of the gear survived so I used them to reconstruct the landing gear. After several hours of puzzle solving, it is back in shape and it just needs the main shaft and the torsion system that George will supply.

Next, I set the plane in position and assembled the lower wings. They are to have 2.5" of dihedral and I blocked them up on my flat layout table. I then set each of the upper wings in place and made the 4 struts such that the upper wings are parallel to the lower and there is no incidence change in the set of the wings. This is key to the proper flying of the plane and it takes a lot of time to get this right.

Next is the wire rigging and I began by inspecting the old wires to see if they were in condition to be used and it they were proper lengths. The X bracing between the struts can be used and only two of the other wires were used on the plane.

The sessions ended with the partial manufacturing of the wires.

Oct 23, 2008

The day began with the covering of the stab after all the final sanding and the completion of the elevators and hinges. The covering was completed and the surfaces look very nice.

Since the stab and rudder are now removable, the stab was bolted onto the plane and checked to be sure it was square to the fuse. The rudder was then hinged to the fin and the bottom of the fuse and the vertical alignment was confirmed before gluing it in place. This was done prior to covering as this is the best way for appearance and for the strength of the joint. Additional blocks were added to make the fin strong.

The upper wing has a center section that is attached to the fuse and this was addressed next to get it ready to cover. Once all the prep was done, I covered the top and bottom of the center section. At this point, I ran out of covering and requested more from George.

Oct 21, 2008

The control system for the tail assembly was constructed today and all the wires were made up to fit the new setup. The servos are in and all the hinges are set and functioning. This turned out to be 4 hours work as the entire system was rebuilt and changes were made to make it a better operating plane. The rudder is pull-pull on one servo and the elevators are now separated for control purposes. Two servos drive the elevators and are set up pull-pull according to the original design of the Pup. The wires are adjustable and are each marked to avoid confusion in the future. There are 6 wires running down the inside of the fuse and it is working just fine.

The fuse sides were prepped for covering and the upper wing saddle was rebuilt and only sanding remains before covering can be done on the fuse and the wing saddle.

 

As the repair nears completion, the final phase is being planned. Once the entire airplane is covered, the the rigging and struts will be made to support the wings and tail. Once that is done, the engine can be fitted, the electronics installed and the paint applied.

Oct 20, 2008

The third wing was inspected and covered in the morning and the last wing was then addressed. This was a new wing as the old one was damaged so badly that it needed replacement. I completed the build and installed the servo with the existing hatch. After making new linkage and putting on the control horns, the frame was shaped and sanded to match the wing on the other side. The last wing was then covered and all the hinges and links were set in place and confirmation of the servo operations was successful.

With the wings done, it was time to begin the setup of the fuse and the tail assembly. The plans shows that the rudder and the elevator are pull-pull and that needed to be worked out before any final work was done on the tail assembly. The servos for the rudder and elevator were installed in the fuse and checked for operation.

Oct 18, 2008

The two upper wings were first to be done. I began with a structural inspection and re glued many of the joints. After all repairs were made the frames were sanded and prepped for covering. The ailerons needed to have the elastic replaced on the upper linkage and that was done with replacement elastic I found and Hobby Lobby the other day. The ailerons were removed and both wings and the ailerons were covered and the linkage hooked up. The pull pin hinges are difficult to work with but give a very scale look to the wings.

both wings came out well and they were set aside for assembly at a later time.

 

Oct 17, 2008

The supplies I need to continue are in hand and George provided a set of plans as well. I spent some time today studying the plans and begriming the final prep of the wings. Once all the items are resolved and the sanding and prep completed, I will cover the wings and move on to the tail assembly and finally the fuse

The wings have many issues and some time will be required to resolve them. All elastic must be replaced, glue joints must be improved all over the wings, additional building will be needed, and hinges and control horns will need to be replaced. This work began today and will continue for at least 20 hours of work.

 

August 27, 2008

The hard points in the stab are now in and the blind nuts that hold the stab to the fuse are in place. The stab and the rudder can now be put on the plane and removed whenever he wants. the Rudder is pinned to the stab but I will wait to glue it in place to be sure the rigging will all fit and that the covering is on both parts.

This concludes the work I can do before meeting with George regarding the open issues on the plane. The project is now in hold -------

August 26, 2008

The work on the stab is complete and the rudder can now be added to the assembly. Since they will be one part of the plane, the two bolts will hold the entire assembly on and the rigging and control wires will need to be removed before the tail surfaces will come off.

 

August 24, 2008

The rebuild includes some improvements to the design and function of the plane. One of these improvements is the conversion of the tail assembly to make it removable. I began to make those changes in anticipation of meeting with the owner later in the week. The stab has been rebuilt after the crash and it appears to have strength issues that should be addressed along with making it removable.

I began by removing the balsa block in the fuse ahead of the stab platform. Checking the platform revealed that it was rebuilt and is not straight compared to the wings. I corrected the alignment problem by building up the left side of the platform and checking it with the wings.

Next, I constructed a double former with two dowels between them and fitted it in the front of the fuse opening. One of the formers will be glued into the fuse and the other will be attached to the stab to allow the front of the stab assembly to be pinned securely into the fuse. Once the formers were in place, I constructed an assembly that will connect the formers to the stab leading edge and allow the assembly to be removed. I made the top of the assembly larger than the finished size so that it can be worked down to the proper shape later.

Once dry, this assembly works to hold the stab leading edge on the fuse. By adding two hard points and screws to the trailing edge area, we will have the stab ready to sand and cover.

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August 23, 2008

Continued to work on the repair of the plane. I began with the sanding of the wing structures to correct airfoil problems and begin to prep for the covering. There are many planking issues on the plane and they will all need to be corrected and then sanded to shape. spend some time on these issues.

I made a list of the items I will need to complete the project and prepped for the meeting with George. There are assembly questions that must be worked out before the covering is applied.

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August 21, 2008

Review of the wings showed some additional areas that need to be strengthened and all those improvements were made in the morning. The first fit of the wings to the fuse revealed several problems with the wing roots and with the anit-rotation pins. The Pins must be indexed to fit properly and hold the wing at the correct angle of attack. If this incidence is not set the same for all of the wings, then there will be odd flight characteristics noted on the first flight. The rigging will control the position and the incidence of the tips, so I am not concerned with that area.

I made all necessary repairs to the wing roots and the wing saddles on the fuse and then set up the fuse to check incidence. This check is done by making a jig that will allow me to look at the angles of the holes in the fuse first. The jig is made from dowels that can be tightly inserted in the fuse and then the level is set on the pins to give a reading.

The measurements on the wings tells a fine story as the four wing roots have .02 degrees variation between them and this is very good for a plane this size. The stab has 1.3 degrees of down incidence and this will simply make the plane climb as the speed is increased. The full scale plane likely had about these settings and I see no reason to make changes at this time. One of the fuse support holes for the lower wing was damaged and I made repairs so that the readings were the same as the other wings.

Next, it was time to put the repaired wings to the fuse and begin checking the alignment. The photo at the top of the file shows the setup of the fuse. I index it level on the pool table by blocking the fuse and adjusting to get level in the flight direction and crossways. The wings are then put on the saddles and temporary struts were made to hold the wings up. As noted previously, the height of the tips is not a concern at this time.

The root of the wings were then adjusted to make the leading edges straight and parallel to each other. The wings were not parallel so this process takes some time and ensures the plane will fly straight after the rebuild is done. The tramble was checked next and adjusted to have the wings on the fuse symmetrically.

I rig a string from the exact center of the fuse as far aft as I can, and stretch it to the wing near the tip. I mark the string and see if the other tip is at the same distance. If they are, the the wings are on straight and perpendicular to the center line of the fuse. I have simplified the setup as it has many details and takes some time. If you need clarification, go to the contact section of this site and email me what you need to know. I will respond and try to help you through the process of checking the tramble. This must be done on all planes before the first flight and after repairs are done.

The same process is used on the horizontal stabilizer. It is set so that it's leading edge is parallel to the leading edges of the wings and then it must be set flat relative to the wings. This is done by adjusting the saddle that the stab mounts on. Once it is flat the rudder can be addressed. Since this depends on the fore and aft position of the stab, I will wait to meet with George before final mounting of the tail surfaces.

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August 20, 2008

Completed the left upper and lower wing repair and inspection.

RIGHT UPPER WING

Began the rebuild of the wing by removing the covering on the structure and inspecting what I found. The wing is not badly damaged but this is not the first crash it has undergone. Some of the earlier repair has to be removed before I could begin to repair the wing. The strut mounts are gone and all the reinforcement material went with it. I rebuilt the wing and created the strut mounts that were needed. I then repaired all the other ribs and spars that were damaged or had been damaged before.

NOTE -- the strut mounts failed in all cases and this indicates a weakness in the design of the wings. I am not confident that I can make the mounts strong enough to withstand a crash, but I have increased the strength and we will see what happens.

RIGHT LOWER WING

This wing is not in good shape and should not be used. There is a spare wing that can be used and it is in fair shape. I installed a servo hatch and reinforced the strut mount areas to align with the other wings. The structure was cracked in many places and they were all repaired. The tip was not complete and the aileron was missing. With all these problems resolved, it is time to begin to fit the wings up to the fuse.

STRUTS ON THE RIGHT SIDE

The struts on the right side are missing. At some point these must be replaced or remade. They are hard wood with slits in each end to accept the strut mounts on the wings.

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August 19, 2008

Began the project today with the left wing set. The wings are damaged and the first step is to investigate the damage and begin the repair. I will repair each section and then Meet with George regarding the covering that will be done. I am not removing covering on the parts of the wings that are sound as we might elect to leave the original covering on the plane.

LEFT LOWER WING

The wing is not badly hurt except where the struts attach to the wing. The ribs and structure are a mess and this will need to be rebuilt and the strut mounts redone before any covering can be done.

STRUTS ON THE LEFT SIDE

The front strut is in good shape and the rear strut is split and needs to be replaced.

LEFT UPPER WING

The wing has similar damage to the lower wing and repairs are needed. I began the repairs by making a new rib from 1/8" lite ply and shaping it to match the wing contour. It was reinforced to the leading edge and the strut mount had to be remanufactured to be mounted on the new rib so that the strut will line up. After all the work was done, the assembly was glued into the wing structure and the other damage to the wing was repaired. The wing is now ready for the covering evaluation to take place at a later date