wpmcnamara

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Through a series of events I managed to loose two planes in one day. This of course set me on a search to find replacements. Through some luck, I picked up a pair of planes used. I got a Great Planes Spacewalker and a Hangar 9 Ultra Stick 60. Both needed a little TLC. The Spacewalker needed less work and was receiver ready otherwise, so it go first priority. With it flying, it was time to turn my attention to the Ultra Stick. This chronicles the reconditioning of the airframe.

I am actually well on my way through it, but I have been taking lots of pictures all the way to document what I did. The pictures are in sequence with the text on each post. So, on with the project.

wpmcnamara

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Given that this is a stick, I started on the wings first as they would be the most complex, regardless of what work needed to be done.

At first glance, the wings looked to be in good shape. They needed a good cleaning due to long term garage storage and an incident with a container of fuel when I was picking them up. There were a number of cosmetic issues beyond dirt though. You can see the abundance of epoxy at the leading edge wing joint as well as various major and minor covering repairs. More importantly though was the structural damage. Looking at it with the covering on, it didn't look terribly bad. There was some minor damage to the port wing tip, but more importantly was a piece of what looked like leading edge that was rolling around in between two ribs.

From that starting point, I began to carefully remove covering with the intent of fixing what needed to be fixed and patching the covering with the correct matching colors.

wpmcnamara

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I won't go through the steps of pulling of the covering, just the end results. It became obvious pretty quick that there was more damage that was immediately visible (remember that hunk of leading edge?) and that it was going to be more expedient, and better looking to just recover the entire wing. That chunk of leading edge came from a large section of damage. You can see the extent in the picture. Not all of the sheeting was busted, but all three ribs were pretty well destroyed. The picture shows what is left once I removed the pieces. I also found a pretty big crack in the sheeting near the wing joint. Further examination of the wing tip showed it pretty busted up and in fact it had been rather "robustly" patched at least once in the past.

All that epoxy on the leading edge joint as well as some other cracks and major dings here and there made me decide it would be easier to just re-sheet the entire port side of the wing, soo... I started tearing more out. Off came the sheeting, top and bottom, out came a large section of the leading edge, the busted ribs were cut off at the spar and the wing tip was take off. The end result looked more like a fish skeleton than wing.

wpmcnamara

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My first focus the the reconstruction was the ribs that needed replacing. I cut three new rib fronts, using one of the existing good ones as a pattern. They were glued in place using 1/16" stick on either side to give the end joint a bit more strength. The exception was the rib on the outside of the outer servo bay. Because of the translucent covering, the out edge of this rib would be visible when the wing was covered. I made a decision that all repairs would be made in such a way as to make them as un-noticeable as possible when complete (another reason I decided to just re-sheet over half the wing). So for the outermost rib, I only used a single brace on the invisible side of the rib. The joint still came out plenty strong.

More to come tomorrow.

wpmcnamara

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With the ribs fixed, I turned my attention to the leading edge. This was a bit more problematic as I could not find anything that came close at any of the area hobby shops. The leading edge looks to be either a trapezoid our a half round with the top and bottom smoothed out for a better joint with the sheeting. I ended up getting four foot piece of 1" triangle stock to use as a starting point. I trimmed the two 45 degree corners so the back was close to the correct width and then glued it in place. With I trimmed them I cut them at an angle so that the sheeting would join well. You can see the front edge in the second picture before I trimmed. The third picture is rough trimmed all around, but not sanded. I then did a rough shaping with a sanding block, mainly to get the sides ready for sheeting. I did not really try and round it any yet.

wpmcnamara

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The wing tip had to be repaired prior to re-sheeting the leading edge. The wing tips are a bit more complex than on some wings due to the construction. I suppose I could have made a "clipped" wing Ultra Stick, but my goal was to make it look as close as possible to the way it came out of the box. The final wing rib had been damage and had to have that back third cut out. The tip is actually the final rib with a balsa doubler/spacer sandwiched in between the formers that hold the actual wing tip piece. This doubler is three pieces, one runs from the leading edge to the front former and one runs from the front former to the back former. The third piece runs from the back former to the trailing edge of the tip and has yet another doubler glued to it, this time made from light ply. This helps give the trailing edge of the tip a bit more strength.

I cut the doubler that runs from the the back to front former back to about 1/4 of the way from the back former. It had been completely destroyed near the tip, but I cut back far enough to get a decent amount of undamaged rib showing. I then cut a replacement piece for the latter part of the rib and the remainder of the middle section of the doubler. The doubler piece overlapped the joint on the rib with enough on either side to make a good strong bond. I then cut the front and rear tip formers and the trailing edge balsa and light ply doublers. After sandwiching the two doublers, I glued them to the rib. In the picture, the tip formers and the tip itself are friction fit with a bit for tape to help hold it. This helped line everything up properly. After that, the tip formers and the tip itself were glued into place. You can see a bit of overhang at the trailing edge to the tip in the last picture. This was trimmed with a hobby knife then sanded.

sir crashallot

thats some good work your doing, there not built to be strong are they there built for lightness unfortunatly creating them to be very weak airframes. but keep up the good work

wpmcnamara

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As it comes out of the box, the Ultra Stick wing is in two pieces which are then joined together. I decided that when I re-sheeted it, I would do it as a single piece with no center joint. There were several reasons for this. I looked at the possibility of separating the wing back into its two sections and found it to be completely impractical. To make a joint in the sheeting at the center of the wing would have required extra cutting and leaving the sheeting as one piece helps strengthen the wing anyway. Turns out a 4" wide piece of balsa was perfect. It left about 1/2" overhang on the leading edge. The sheeting was taped front and back to give it the proper shape while the glue dried. Once the glue dried, the leading edge overhang was trimmed off.

The center section from the leading edge sheeting back to the trailing edge two large for a single piece. I actually joined three 6" wide pieces then cut it in half to get pieces for either side. They were trimmed and sanded to tight fit and glued in place. At the same time, I glued on the various rib caps that had been removed due to damage. I started with the top of the wing and the bottom was a repeat except for the center section. Two holes were cut so the servo leads could be fed through. Once all the glue was dried, the new sections of the leading edge were shaped. Shaping was done with a sanding block with 120 grit paper, followed by 220 grit. After shaping all the joints and any dings in the sheeting were filled with balsa colored filler and the whole thing was sanded smooth. A final sanding was done with a soft, spongy 320 grit block.

wpmcnamara

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With the sheeting complete, it was time to take a look at the the ailerons/flaps. The needed to be re-hinged. Rather than put CA hinges back in, I opted to use hinge points. I'm using Great Planes hinge points, not Robart, but they function the same, and for that matter they look pretty similar too. I went with the Great Planes version as they are a translucent white plastic instead of the gray of the Robart's. To reinforce the aileron/flaps I glued a piece of 3/8" triangle stock to the back of the leading edge so the hinge pins would have a little more depth in which to sit. The second picture gives you a better view of the reinforcements. The stacks of wood in the first picture of 3/8" square stock cut to provide reinforcement for the hinges in the wing trailing edge, which is very thin. These were glued in place with plenty of glue to ensure a strong bond. Each hole was drilled with a 1/8" bit and then the first 1/4" was drilled out further with 5/32" bit and trimmed to allow the center of the hinge to sit flush with the back of the wing. All the hinges were dry fitted. The aileron/flaps were measured and notches were cut for each hinge point and the drilled. To test the fit of everything, the ailerons and flaps were all dry fitted as well.

wpmcnamara

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At this point, my posting has caught up to my actual work, so things may slow down a bit depending on how busy I am this week. I need to drill the holes for the dowels that mate the wing to the fuselage and I need to test fit the servos I have in the wing servo pockets. If there is any modification necessary to fit the servos, I want to do it now. Once that is complete, I can start the covering.

wpm

wpmcnamara

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Ok, so I had a week or so of down time and decided it was time to fit the wing with the retaining dowels. I drug the fuselage in from the garage and started looking at it. I pretty much decided at that point that the wing dowels needed to wait a bit until I got the fuselage in better shape.

The most visible damage was that the landing gear block had been ripped out. However, looking closer, I found that the former/bulkhead that joins to the landing gear block had broken and ripped out too. I went ahead an pulled the top of the nose off and pulled out the fuel tank to get a better look. Since I was going to have to replace the entire former, I didn't want to drill the dowel hole in the wing until I could fit it with the replacement former. So the wing go set aside and I started to strip the body.

wpmcnamara

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I started with the tail first as it had some visible fuel damage where it had seeped through the covering and into the balsa. Once I got the horizontal stab cut off the body and the old covering stripped, the extend of the fuel damage became apparent. I decided the easiest thing to do was simply replace the leading edge. Since it is one piece across the entire stab, replacement looks to be fairly straight forward. I cut each of the glue joints to get it ready for the replacement piece. I don't have photos up of it yet, but I am using a piece of square stock that I will sand to round the leading edge.

wpmcnamara

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I have been remiss in posting updates here, but I have made a lot of progress. So, now it's time to catch up on the rebuild log.

I stripped the covering off the fuselage and pulled the bottom sheeting off to see what damage there really was. You can see the non-existant former that attaches to the wing mounting block and the landing gear block. As you can see, the landing gear block was just ripped out and it took most of the former with it. With a bit of razor blade and dremel work, I extracted the rest of the former and wing mount. What isn't really visible in any of the pictures is the fuel damage to the lower edges of the side sheeting. It was bad enough that I stripped off the bottom 3/4" on both side front to back. The photo is of one of the sides and you can see the formers and plywood frame.

Starting with the wing mount and former, I began rebuilding the body. I cut a new F2 former and doubler that would make up the wing mount. They were first glued together, then mounted in the fuse.

wpmcnamara

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With the former back in place, I could put in the new gear mounting block. You can kind of see in the picture that the gear block is actual a sandwich of 3/8" and 1/8" plywood. I didn't have any 1/2" aircraft grade plywood handy and didn't really feel like shelling out for some just to make gear blocks. I glued in some 3/8" triangle stock to give the joint to the former a bit more strength and to give the sheeting aft of the gear mount something to attach to.

wpmcnamara

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With the nose a bit stronger, I moved back to the rear of the fuselage. When I removed the lower 3/4" of side sheeting I also took out the stringers that ran from the tail forward to the interior plywood frame. I started by replacing those. Since I had decided to move the tail servos back to help counter the Saito 100 going on the nose, I decided to make the rudder servo mount before I went any further. I cut a pattern from card stock and them made the mount out of 1/16" ply with 1/16x3/8 hardwood strips for the mounting screws. Once the whole mount was glued in place, I cut out the hole for the servo.

Before I could install the mount for the elevator servo, I had to replace the lower section of sheeting. The holes for the former tabs were actually "measured" buy clamping the front of the strip in place and then pressing it against the formers. Once I took off, I just cut out the indentations.

Sessholvlaru

Are you going to duplicate the stock covering scheme? Or go for something unique? I don't know if it would be good or bad to see this as indistinguishable from a new one, considering the effort going into it.

wpmcnamara

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I haven't quite decided yet. I did take notes on the position of the striping and such on the original scheme prior to pulling the covering off. I do think there will be some modifications regardless. The underside of the wings will likely look different to help with orientation.

wpmcnamara

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With the rear sheeting replaced, I made another servo mount, this time for the elevator servo and cut out it's spot. The third picture is a test fit of the two tail servos. I had to trim the openings slightly and trim about 1/4" off the vertical stab where it meets the sheeting, but otherwise, they fit quite well.

With the tail well in hand I went ahead and put on the sheeting strips for the front half of the fuse. Second picture, you can see both sides done and trimmed up to the front landing gear mount. Then, I went ahead and put the bottom sheeting on the tail. Notice the high tech method for applying continuous pressure... After a bit of trimming and sanding, it looks pretty good. I left the slight overhang at the horizontal stab mount in place as it helps hold the stab in place during test fits and it blend the fuse into the stab a bit better.

wpmcnamara

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Somehow or another I managed to loose a bunch of pictures I had taken of various progress points. Very annoying. I went a retook a few, but unfortunately, you only get to see the results of the work, not how it was done.

1. The repaired horizontal stab.
2. The new rounded leading edge of the stab
3/4. There was some serious hangar rash on the trailing tip of the elevator. I cut it out and put in replacement 1/8" sheet that was then sanded to match the contour.
5/6. To simplify re-drilling the holes for the wing mount dowls, and to strengthen the mount some, I put a block mount into the wing. I actually cut out the front of the wing to fit the block. It will be a bit more challenging to cover, but I should never have to worry about the mount.
7. Test fitting everything. It's actually starting to look like a plane again.

wpmcnamara

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Before I put the sheeting on between the two landing gear blocks, I put in a mount for the fuel tank. I am moving the tank out of the nose and under the COG. Since the motor is mounted and 90deg I don't have to worry about the tank/carb vertical relationship and I plane to use a Perry pump to keep the motor fed. Each strip is 1/4" basswood running from the front gear block to the F3 former. The tank will be wrapped in foam and strapped to the beams. I have piece of 3/8" angle balsa under each one to give more contact on the F3 former. I actually made a mistake when I glued them in in picture. I had to cut out the middle strip and re-do it. When I went to put in the blind nuts for the front gear mount, I found the middle hole came right through the middle beam. I trimmed the beam so that it would pass over the nut and re-glued it. I didn't take a picture putting in the middle section of sheeting. It was really just more of the same.

With the middle sheeting in and the gear drilled, the last part of the bottom of the plane was the nose box. Hanging a Saito 100 off the nose made me question the strength of the firewall and nose box. I put 1/4" sticks around the the inside to give mounting points and then cut a light ply doubler to strengthen the bottom. It was carefully cut and sanded to be a tight, press fit. With it in place, the final section of bottom sheeting was glued down and sanded.

Since I now need to be able to get a rough COG measurement, I went ahead and temporarily mounted the tail gear. It has 3/4" #4 socket head screws that go all the way through the horizontal stab and into it's mounting block in the fuse. Even prior to CA'ing the holes, anything that manages to tear that tail gear off is going to do serious damage to the rest of the plane. I did encounter a snag after looking at the tail gear once it was mounted. The joiner for the elevators interferes with access to the rudder where I would need to mount the connector for steering the tail wheel. I think I have figured out a solution, but that is for another post.

wpmcnamara

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I took a moment to weigh the airframe to see how things are going. With all servos (no linkage), a Saito 100, prop, prop nut/spinner, fuel tank, flight pack, etc it weighs in at 3.01kg (6lb 10 1/4oz). Covering will add another 100-150g. I'm guessing that I'll end up in the 3.3-3.5kg range dry RTF weight. That will be 10% or so over the top end given on the Hangar 9 site and I have not made serious attempts to keep things light.

wpmcnamara

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Only one picture today. I put the airframe on the CG machine to see how things look. With the flight pack in throttle servo positioned as in the picture, it balances with no added weight. I'm pretty happy about that. Tomorrow I plan to build the mount for the throttle servo and flight battery. I am debating making the top sheeting on the nose removable so that I can get to the throttle servo easy. My concern is whether I can seal it up well enough to keep fuel spray out.

I did have one bad event today. I was working with the tail wheel mount and I was adjusting the angle of the bracket to get better clearance for the steering hardware. The stupid thing just snapped in half. I have no idea who makes/made it as I salvaged it off an Edge 540 I got used and later turned into toothpicks. So now I have to find a suitable replacement tail wheel. Annoying, but only that.

wpmcnamara

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Now that most of the re-construction is done, I getting to the "fun" parts.

First up was the mount for the throttle servo. It was mounted as far forward as I could get it and still have room for the servo arm to swing through the full arc. The third picture is test mounting the servo and plumbing. To make the plumbing a bit easier and to keep as much fuel out of the body as possible, I put bulkhead fittings through the firewall for the fuel (blue) and pressure (yellow) lines. You can also see the cut out for the throttle pushrod. I haven't quite figured out how I'm going to seal the opening yet. The final fuel related item is the fuel dot for filling. You can see the ply doubler to help strengthen the balsa sheeting a in the throttle servo picture. This is the one from the outside (pretty boring really).

wpmcnamara

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Now, on to control surfaces. The ailerons, flaps, and elevator all have Dubro 4-40 ball links on the servo side and 4-40 Dubro Saftey Lock Kwick Links on the control surface side. The rods are all 1/8" carbon fiber with 40-60 size push rod ends from connectorsrc.com. The in the two aileron pictures, I was still using the stock Hitec servo arms which really can't be drilled out to accept a 4-40 size screw. As you can see in the elevator picture I switched over to Dubro Super Strength arms. The rudder pull-pull setup is a Dubro 4-40 set. I don't know who makes the servo arm on the rudder servo as it came with the servo when I bought it way back when it was installed in an Edge 540. I am going to have to trim the posts on the horns a bit to make sure I have clearance between the rudder and elevator through full deflection.

wpmcnamara

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I test mounted the receiver and battery pack on the rails I put in for them. Both have 1/4" foam underneath and are held on with velcro straps, same as the fuel tank. It's a reasonable trade of between soft and secure mounts. Since the fuel tank was moved back, I had to re-position the charge jack/power switch. I moved it as far back as I could get it so that it is reasonable accessible when the wing is on. I didn't take a photo of it, but I made a ply doubler for it as well. Helps keep you from pushing the jack through the sheeting when you plug it in to charge. Since I moved the jack, I had to fill the old hole. I cut filler from 1/8" balsa, then used it as a template to cut the hole in the sheeting. I intentionally cut the sheeting hole about one blade width smaller than the filler plug. The end result was a nice tight pressure fit. With everything as flush as possible, I went around the seam with extra thin CA from the inside. It's probably some of the best wood work I had done this whole project.