TEBerg

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It has been a couple weeks since I’ve had the chance to post. I am currently in Colorado visiting with family and enjoying vacation. Tomorrow we will head south from here and travel through New Mexico and Arizona, taking a couple of days to see cool stuff like that big hole people call the Grand Canyon…

We will arrive back in California and stop down in Long Beach. The USCGC Eagle is sailing the west coast this year and we are going to see her at the Port of Los Angeles. My Coast Guard Academy class of 90 had the opportunity to sail her from Connecticut to Australia for a Tall Ships Parade celebrating their Bicentennial (1988). That was a great trip/experience. Well, since I did have the opportunity to become Shellback and Golden Dragon on a Tall Ship, sailing ½ way around the world, I really want my wife and son to get a tour of the boat [laugh] and see a little bit of my experience.

Sorry that none of this relates to the Skyraider Build.. So, let’s get back to the airplane.

I finished the bottom sheeting on the left wing and took care of some of the rough sanding. Then cleaned off the building board and started the right wing ½. One thing I can say was that building the right wing went much faster than planning and fitting stuff on the left. When I had to drill holes to make things fit in the left wing ribs, I also did the same to the right wing ribs. So, most of everything was drilled, fit and ready to go. This time I even remembered to put the outboard wing tube in place BEFORE the inside section. I did have several delays in order to get stuff ready for the above-mentioned vacation, but got the wing completed to a point where I could take it off the building board. I started but did not finish the landing gear mounts yet and have the bottom leading edge sheeting, but that should be completed pretty quickly after we get home.

While I’m traveling, I’m working out a few last modifications I want to do for the rudder and elevator counter-balances. The kit just has straight surfaces, but I’m going to add some semi-scale shape to them. No, I’m not going to duplicate that weird shape of the rudder, but I think the counter balance will be pretty easy. I just want to make sure I don’t create a weak point on the horizontal or vertical stabilizers.

That’s it for now. Hope you all are having a great summer flying…

TEBerg

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I'm back from vacatin and did complete a little bit more on the Skyraider..

Here is a photo of both the "rough" wing halves... I say rough, because they are not smooth or near completion at all [laugh].. But, hopefully I'll get a bit more completed very soon.. I'm going to work on the aileron servo hatches/mounts and then the flaps. If that all goes well, I should be working on the tail feathers pretty soon..

TEBerg

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I did not get as much building completed during August as I wanted. However, I did make some progress and did find a few “fixes” that may be of interest to other people looking at this kit/build.

Since the “rough” wing I started on getting ready for the hardware. Pictures 1 and 2 show the servo covers I designed and made for the aileron servos. I kept the servo plates lined up with the wing trailing edge sheeting and that gives me lots of room for the servo wires to route into the tubes. If I was doing this again, I would probably move the servo forward about ½-inch for weight distribution and lining up the pushrod. But they will still work fine for this project. Photo 2 is the servo rails gluing with a true Geologists weight [laugh]. The third photo shows the servo cover and a rail where I will mount the Vortac bomb release. The pull cable for the bomb release routes through the red nyrod you can see in the first open wing bay.

Now, on to more fun – Right. I went to line up the ailerons and noticed that the inside of the aileron is about 3/32 thinner than the wing!! Photo 4 shows the difference in thickness. Well, that’s kind of new for me. I have seen wider ailerons, but was a bit worried about the difference. Also, since I’m adding flaps, my ailerons are about 4-inches shorter than the stock ones. So, on a “stock” kit, there would be an even greater gap. So, I decided to glue a doubler on top of the aileron where the thickness did not match, about 10 inches of the 15-inch ailerons. Photo 5 shows that the thickness with a doubler lines up a bit better.

After that decision, I went ahead and started my build-up flaps. I used the end pieces cut off the stock ribs, some extra 3/8X1/2 balsa for the root of the flap and added ¼-inch thick end caps to the flaps. Photo 6 shows the laminated ailerons and the build up flaps before I sanded them down to the correct thickness. On the flaps, I did the rough sanding with the top sheeting taped under the flap to get all the angles correct. After I sanded the "guts" of the flaps down to the correct angles and thickness, I added doublers for the hinges and a mounting plate for the control horn (you can see the locations marked in pen). Then I glued the top sheeting on the flap and it is ready to mate with the wing and final sand.

Since the last photo, everything has “rough sanded” down to a pretty nice shape. I am currently fighting with making the retract bays look better (you’ll see what I mean later) and have the wing tip blocks glued on and some big wedges sawed off the tips. Now, I just have to get back outside with some 60-grit sandpaper and start making this thing look the right shape.

Next installment will be the saga of covering the ugly retract mechanism. This is a trick in this 62.5-inch wing. The gear is really bulky compared to the scale of the wing.

Launch Pad McQuack

Tom looking forward to your thoughts on the gear issue. The 2 skyraiders I have seen done both had retracts incoporated into them. And neither were that well done from a scale stand point. Unfortunatly Global was just not thinking about us when this was designed. But what you have is looking good so far, keep it up.

Forrest

TEBerg

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The flaps and ailerons are currently rough-sanded. Here are a couple of pics that got me there. First pic is where I had tapped the “built-up” control surfaces to the wing with 1/16 spacing between. Second picture has the hinge doublers and ply plate for the control horn glued in place. Then a shot of the “rough” control surfaces. I will tape them back in place and final sand them after I get the leading edge and gear pods worked out.

The forth pic is a cool shot if you can make out what I’m aiming for.. Look at the wood block on the wing tip (Close to the window/shutters). It does have some definite washout built into the wing when compared to the root rib (blurry in photo). At first I had my doubts how it would work when all the ribs were glued to the trailing edge and bottom main spar. However, it looks like the change in the leading edge down the length of the wing ribs definitely did the trick. I was very happy that both tips look to have matching washout – That’s a good thing….

TEBerg

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As I finish up some of the sanding and steps on the wing, I got going on the tail feathers...

Now, the kit has been “pretty OK” for parts supplied and how they fit. Well, I am apparently missing some things I needed for the vertical stabilizer and/or horizontal stab. The biggest problem was the trailing edge post for the vertical stabilizer was not in the kit/box. Now, I’m pretty good about checking which parts I’m cutting and using during each step, so I’m going with the opinion it was missing. Along with that, I did some quick measurements on the 1/16th balsa provided and I can’t find enough to cover the surfaces… OK, off to the store again. Not a big deal, but all the extra still adds to the overall cost of a kit; however, since this one is no longer in production, it is just something to look out for if you are building one of your own. The nice thing was that I just needed 3/16 and 1/16 for the surfaces and the local Michael’s Craft Store has a nice box of Midwest balsa. It is a lot closer than the local hobby shop.

OK, on to some building/modifications. Forrest had warned me that some guys needed to beef up the horizontal stabilizer and it was also referenced in a February 1995 Model Airplane News, Field & Bench review by Pat McCurry and Frank Tiano also built one.

The two things I wanted to “fix” on the horizontal stabilizer was the fact that it has been noted to be too weak and flutter/crack during high speed flight and that there are no counter-balances on the elevator halves. Here is a review of my re-design/modifications. The photos show the following items:

I purchased a stick of 3/16 X ¼ basswood to use as a spar across the stabilizer. I hope this will provide tip-to-tip strength. Then I enlarged my 3-view drawings and some other Skyraider plans (Taylor) to estimate the counter balance. I ended up with them being ¾-inch wide and 2.25 inches across. This fit very nice and you can almost tell in the 2nd photo that the horizontal stabilizer trailing edge was made up of 3/16 X3/4 balsa. One easy cut to provide room for the counter balances. I will glue and blend them in the front of the elevators.

The next photo shows the internal frame of the horizontal stabilizer laid up and glued. I also added some gussets to the inside corners of the center planks to help transfer any flutter or cracking weak points. I also ran into a little problem that the middle pieces were not the right size for the stabilizer, I had to grab some 3/16 scrap and add about 1/3-inch to the planks to get the correct distance from front to back on the stabilizer, even with adding ¼-inch of basswood to the width. I did have to trim down the tips to the correct thickness.

Well, as I mentioned the kit did not provide enough 1/16 sheeting in my estimations. Hopefully I used this to my advantage and I purchased some 4-inch wide balsa from the store. I also found a very hard plank of 3-inch wide 1/16 that was a suggestion in the Field & Bench review… The kit shows to sheet the top of the stabilizer with all the grain running span-wise. I glued the hard 3-inch balsa sheeting on the “bottom” trailing edge of the stab. Then I cut the 4-inch sheeting to have the grain run parallel with the stabilizer leaning edges. This did put a splice in the center of the stab, but I think the strength I gain from the cross-grain will be an improvement. You can see the new pieces in the fourth photo.

The last photo is the stabilizer sheeted and pinned down to dry. On the Top of the Stab, I decided to use the 4-inch wide from the trailing edge forward to give me a little more “smooth” surface. Then cut triangular pieces from the kit’s balsa sheeting to cover the front the same as the bottom.

OK, just a couple more steps on the landing gear issue and I’ll post some photos of how the wing modification looks… Then I should have the vertical stab done.

TEBerg

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Hey Forrest, here is my plan for the landing gear wing pods. I don’t have a way to make them “Scale” because the size of the landing gear mounting is way out of proportion for this size plane. That would take a completely different geometry of the pivot point. Sierra Design and some of the other rotators are pretty much the same type of mounting. Therefore, we are currently stuck with what is out there. I wanted to edit this post and add: Lado Retracts DO have a different geometry and the extension/rotation is below the mounting screws!! It might be worth a look at this gear to see if the 90 degree rotating retract can work.

But, my goal is to go with what I have and is the Least Ugly [laughing]...

I looked at the retract geometry back when I made the rib doublers. At that time, I decided to have the mount outside the leading edged sheeting to keep the strut parallel with the flat-bottom wing and place the tire completely in the wing. I will have to take a little notch out of the lower spar for the thickness of the RoboStrut. The real plane had the strut and axel below the wing with the gear doors (on the AD-4 and AD-6) bulged out to cover them over. So, that was the same geometry I chose to use the Robart 100-degree rotating retracts which put the wheel out in front of the leading edge. The other brands currently have only 90 degrees and I was worried about a nose-over problem. I looked at trying to hide the gear with different mounting angles and looking at trying to bury the retract more into the wing, but again worried about ending up with worse ground handling or nose-over problems. Sam (hellcat 1) has a Skyraider with retracts in it and I think his drop inside the wing a bit more. He may have some pics of that setup.

Ok, off to what I have stuck under the wings of my plane. The first photo shows an “open” set of rib doublers and the lite-ply retract ribs extending beneath the leading edge. I remembered to drill out an access hole for the air lines before I blocked the front end. The retract cylinder does not protrude through the plywood doubler I added, but I drilled the hole big enough to keep the lines from kinking (I hope). Then I glued blocks on the front that were wide enough to allow for a nice round front to the landing gear mount.

One problem with the gear is that they are so wide that you need a huge amount of extra out front to make up for the thickness in order to have a round shape at all. So, I measured out the width of the plywood doublers and drew out the arch/curve that looked best. That’s how I decided how far to build out the balsa blocks. I thought of carving a block to look like the leading edge and then make a plug for a fiberglass or plastic cover, but that would end up as a LOT of work and I don’t think I could make it look much better. Especially for this sport-scale project.

OK, back to photos. I rough sanded the blocks to the shape I needed and then sanded the shape of the leading edge. I indented the leading edge just a bit into the gear pods so they could be sanded to a bit of a bulb. The photos show the notch in the leading edge better than the rounded profile, because it all starts to blend in a little in the front view. The side view shows a little better shape. I still have a little putty work to do before the final sanding.

Now, my original plan was to use vacuum-formed plastic from the Top Flite P-40. The scale P-40 pods are not much different than the Skyraider. They are both pretty small for the aircraft. But, the RC mock-up always seems to end up pretty bad in 60-size planes. Anyway, I purchased the P-40 pods back when I ordered my 1/10th scale pilot to give them a try. The next couple of photos are the rough-cut plastic pod covers taped in place on the wing and compared to the sanded blocks.

The plastic pods have a nice rounded shape, but they are really HUGE [laugh]. So, what do you all think? Go with the smaller wood blocks and leave the bottom open?? Or, cover the gear up completely with the vacuum-formed plastic??

In the last photo I opened up the front blocks to fit the landing gear rails. After I glue the wing halves together I will glue in the mounting rails while I line up the gear struts.

So, not much to ‘scale’ but which look is less “ugly”, the plastic or just the rounded balsa pods??

TEBerg

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Just a quick note/update. I finished rough sanding the wings and matched them up with the ailerons and flaps. I spaced the ailerons and flaps with 1/16th balsa between the surfaces and taped them in place. Sanded one side, than taped the other side and sanded the opposite. Lastly I blended the ailerons, flaps, trailing edge and wing tips together. Not too bad, the thickness along the trailing edge from the doubler I added on the inboard ailerons and the build-up flaps I manufactured took some extra sanding.

It will be time to mark the robart hinge points before I bevel the surfaces. I think I'm going with a double-bevel on the ailerons and a bottom-bevel with a rounded top edge on the flaps. Larry Sutherland showed me how to put thin plywood on the trailing edge of the wing to cover the top of the flaps. If that works out for me, then it will give it a semi-scale finish look to the intersection between flaps and ailerons.

Launch Pad McQuack

Tom is there a way to add a wood cover to the wood pods to enclose the retract? Even is you were to just cover the rails on the side I think you would be in like Flynn.

My 2 cent....Forrest

TEBerg

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Forrest, Thanks for the thoughts.

I originally wanted to carve plugs and have Larry vacuum form some custom covers for me. However, when I went to make a plug, it was way over my head to produce two accurate replicas of the wing and pod areas for the right and left panels.

I looked at carving some wood pieces to fill in beneath the gear, but the mounting bracket covers a lot of area and I could not figure out a way to make removable covers.

However, if I made “expendable” covers that I glue in place, sand and cover after the gear are on the plane it may work. But, they would have to be cut off if I need to work on the gear.

I also keep thinking about making some fiberglass covers. I have seen where other guys have put down “temporary” Monokote on the wing and carved foam right where they wanted the fiberglass part. Then they glassed the part right on the plane. I think that would be a pretty good option, but I have never made fiberglass parts. That makes me kind of shy away from trying that if I don’t gain a whole lot of “return” for it. After all, it is no masters scale airplane [smile].

Covers may be a "next season" project...

TEBerg

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I will try and break up the next topics onto a couple of different threads… That should keep the number of pictures on any one post down a little. It will also allow you to skip over my long-winded explanations faster [smile].

With the horizontal stabilizer sheeted, I went on to work with the vertical stab and rudder. Again, the setup on this kit is not scale at all, so I again measured off of the 3-view drawings and the other Skyraider plans. I ended up going with a 1-1/8 counter balance because that made the split right along the rear stabilizer brace. Which, buy the way was one of the parts NOT Included in the kit…

The first photo shows the top piece to the vertical stab and where I marked it to cut (matching the brace thickness). I used a height of approximately 2-1/4 inches for the counter balance. Now, with the odd shape of the “real” Skyraider rudder, this still does not match up to the true profile. But it fit the best and looked a lot better to the eye.

The next photo shows the regular layup with the stabilizer ribs and how I reinforced the top in front of the counter balance. That was an extra bit of rib material with a gusset added. After this the stabilizer was sheeted (with balsa actually included in the kit) and the edges rough sanded

On the rudder I added the counter balance to the leading edge and glued the cap left over from the stabilizer on top. That made matching the existing profile very easy [smile]. Then I trimmed the bottom of the rudder to match my profile which will include a tail hook. Because I’m using Robart hinges I also glued some additional rib material in the hinge areas (3).

From here I need to sand the rudder to a taper and glue on the sheeting. Then it will be time to blend the rudder with the vertical stabilizer and round/bevel the edges as needed.

TEBerg

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Back to the wing…

I had read on some posts or blog about the Global Skyraider having an issue with the center section being week and possibly failing. Now, I don’t know for sure if people were talking about the Global ARF or the kit Skyraider. So, I’m going a little safer here.

I prepared the center brace per the instructions of sanding it to fit between the wing spars and ½ into each wing. The instructions nor the plans give you a dihedral angle or a measurement to prop one tip up. Per the instructions, the dihedral angle is set by the brace… OK, I was pretty darn careful to sand enough to fit and not sand down too much. Which did end up giving me a “left and Right” side to the brace for the best fit (things are a little asymmetrical). I did compare the angle of the dihedral brace to the dihedral angle “gauges” they gave me for setting the angle of rib R-1 and I also used for setting my landing gear ribs (so the gear would be perpendicular to the ground) and it all matched up very well.

Then I matched the dihedral angle and cut a brace out of light ply to run along the rear wing braces. These braces are balsa, so I figured that using light ply was a lot better than nothing.

Everything was then sanded to fit the two wing halves as best I could. I did discover (again) that the plywood ribs had a slight warp from the plywood cut-outs. So, that did leave a little gap along the top in a couple of places. But overall the fit was not too bad. I glued in ½ the brace(s) per the instructions and let them set up.

Then, I mixed the epoxy, wet the inside ribs and put plenty more in the wing brace area and on the brace. Fitting them together for the best “fit” did require a couple of clamps – Trailing edge, center ribs and leading edge. Then in order to keep the top center “closed” I used about 2 pounds of weight on top, with the wing tips braced up, while the epoxy set. Everything looked pretty true and the landing gear pods were even level with the table top and each other – That’s a good thing.

Next I lined up the landing gear parallel with each other from the front and side. I double checked to find out what angle and which position gave me matching gear in the retracted position and extended. Per many recommendations, I glued the landing gear rails into the wing ribs and doublers while they were mounted on the retract units. There was a little play between the wing ribs, but just barely. I needed to tweak one gear a little to one side and the other one needed to have the front corner held “down”… Then everything was glued in with epoxy and tape held the minor adjustments.

The last photo is the “teaser” photo… I’m getting ready to fiberglass tape the center section of the wing. I have used a couple of different techniques to accomplish this. But, after some looking around, I’m getting ready to try the Peel-Ply method… Here is one thread: http://www.rcuniverse.com/forum/m_6496478/tm.htm

The photo of these ugly little patches is a great recommendation from Mike. Practice, practice, practice – some of the tape you see is actually over the epoxy resin to see how it all feels after different laminations. Edited to note: the white/light streaks you can see on the top balsa square is where I spray on too much 3M77 spray and it plugged the fiberglass weave. No resin got through the mesh and into the balsa = Bad. Mental note, IF you are going to use some tack glue, use a VERY Light coat. I have used the blue tape before, based on a recommendation from a guy in my club, and it does a lot to smooth out the fiberglass and resin. However, it leaves a rather sticky film on the epoxy. The polyester “peel-ply” does a great job at smoothing out the fiberglass and resin. Then you pull it off to a nice clean finish... Check out the discussion in ExperimentalAviator’s Sig King Kobra thread.

TEBerg

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So, with the landing gear rails glued into the wing, I could pull off the Robart 615’s and get to work on the struts and setting up the gear.

Well, what a surprise to see that I apparently have TWO DIFFERENT runs of the 380 Robostruts. The photo shows the obvious (approximately 1/8-inch) difference in the “spring” length. Along with that, the bottom set screws are different sizes and the axle hubs look different. Not that you will ever see that, but it is another size of crap I need to keep track of [laugh]…

Well, I purchased these on-line and decided I did not want to take the time to explain it or send the two struts back for a trade. Besides, I figure that someone has to end up with two different struts – might as well be me [smile]. And, the first person who says “Hey, you have different struts” can buy me a matching set…. I don’t know how you would ask to avoid this while shopping on-line. But it is something to look for when you go to buy these struts.

So as you see in the first picture I marked the struts to be even when I cut them off. You can also see one of my measurements where I was thinking about going 1/8-inch longer [grin]. Then after I cut off the hollow struts, I ran the axle through both hubs and ground/cleaned up the ends evenly. Then I followed Robart’s instructions and got the struts mounted on the 615’s. The next photo shows they do look different, but when you put an airplane on top of them, you may not see the difference.

When I was working on setting up the 615’s I discovered that the 100-degree retracts not only extend out 100 degrees – They Rotate UP 100 Degrees (the amount the wheel turns). Kind of hard to see in the picture of the bottom of the left retract, but the axle is pointing a bit to the right of center. It has rotated past 90 degrees and is actually past center. Well, at first I was worried about part of a tire sticking out of the wing. But, since I decided to make my gear mounts level (meaning perpendicular to the ground and not with the wing) there is a little difference between the flat-bottom wing and the landing gear pod. The wheels happen to rotate past center end actually match up pretty well with the angle of the wing dihedral… Not too bad for dumb luck.

The last photo is very hard to see what I’m looking at, but it is a slight bit of toe-in. I had read the discussions about the Robart 615’s (more than once) and one debated point was toe-in. Well, it may put some extra stress on the rotation mechanics, but I opted to go with a couple of degrees. This also made the retracted angle of the tire a little less. One thing to note is that per some of the Robart 615 problems, I went to the hardware store and picked up some ¼-inch 6-32 set screws to help hold the “duck foot” pinion on the strut. I also ground down a “healthy” flat spot for one set screw. For the second set screw in the duck foot I used the technique of cutting an “X” into the strut instead of trying to grind matching angles. I also went with Blue LockTite in every setscrew!! With luck it will all hold up. If not, all the Sierra Gear guys can tell me “I told you so.”

I’m OK with that [smile]…

Destroyer of Airplanes

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Tom,

Boy am I really glad to find this thread. I just got a partially built Global Skyraider. The fuselage is in pretty good shape, but the wings need lots of work. All I got with her is the assembly booklet, I did not get the plans. I also got a cowling and canopy from ("another Skyraider kit) that I can't identify. I found and ordered a set of Skyraider plans from Uswing on ebay. With a little luck there will be enough detail that I can go back into the wing and add flaps and the three dive brakes to the fuselage.

I read with great interest your landing gear description I've been wondering how I'm going to make that all work out too. Looks like I'll be lucky and you will have it all figured out before I get there.

I intend to power my plane with a .60 electric so I will be doing extensive rebuilding in the forward fuselage to add a quick change battery set up. Possibly by turning the oil cooler cowling into some type of a hatch. I have a ways to go before I catch up with you, but it's nice to know there will be someone else trying to solve the problems.

Regards

Paul
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TEBerg

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Hi Paul,

I’m glad to hear from you… Feel free to jump on in with any ideas and results of your project.

The Skyraider fuselage does look to be in good condition. The engine cowl looks like the two-piece from Global, because the next Skyraider this size was from Sky Shark and came with a fiberglass cowl. You can pick up a new cowl, the air scoop and oil cooler for this kit from Fiberglass Specialties.

To retrofit flaps into the wing, there was a post here: http://www.rcuniverse.com/forum/m_3493781/tm.htm about adding flaps to an ARF plane. It may work well for your wing. I don’t know how you would do the removable top/cover for a battery hatch because of the way the fuselage is built in sections. Everything is kind of blocked off, but I have read about other electric versions of this plane so it must work.

I’ll send you an e-mail with a PDF of the 1995 Field and Bench review on this kit. It shows a basic drawing of how to retrofit the Robart Retracts into the wing. Also, my wife scanned the original plans and re-printed them on an engineering plotter (her previous work place). So, I had two copies without copier distortion to use as my “working” plans.. I have chopped those copies up into sections for building and marked on them. However, if you e-mail back your address, I’ll be glad to send one of the used copies up your way. You will be sure to have the Global Skyraider plans that way.

TEBerg

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Last week I wrote about gluing the wing together and working on the landing gear. I have the holes cut for the wheels and grooved into the main spar for the RoboStuts. I’m using 2-3/4 inch wheels and opened the holes to 3-inches to give me a bit of clearance. The 3-inch holes just fit into the wing in front of the rear wing spars. I had to grind/cut out a bunch of the “extra” rib from the retract mounting and a bunch of one of the normal rib locations.

I used 1/32 plywood to tie the top and bottom sheeting together for strength. I only added the plywood to the sides of the wheel wells, because I had already added some extra shear webbing behind the rear spars to close off the space. I wet the plywood and bent/glued and clamped it in with Gorilla Glue to help fill any gaps. I also epoxied a 1/8-inch plywood doubler (4th photo) underneath the main spar because I did not like how much I had to grind into the spar. In that photo you can see where I still have some small gaps between the plywood and the wing ribs. The geometry of the wing tubes, round cutouts and all was a trick, but it is close.

TEBerg

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I had a couple of additional “catch ups” to do on the project.

I will be the first to say I can learn from other people’s trials. Per the suggestion from Wingman, I opened the fuselage sides back up. With adding some extra detail to the tail feathers I may be adding extra weight. So, I don’t think that filling in the lightening holes would have provided much benefit for the risk of needing extra weight in the nose… Here is a photo of the fuselage opened back up.

Side Note, you think CA fumes are bad while gluing… Be very careful using a Dremel tool and a sanding drum on CA… Boy did I get a couple of bad hits from the smoke off the grinding. Even outside, just being down-wind a few times was very sensitive.

Next photo is the roughly finished vertical stabilizer and rudder. I had tried to estimate the gap around the counter balance during building and apparently missed and there was too much gap. Therefore, I added some extra balsa shims to the front and bottom of the counter balance to give me some working room during final sanding and hinging. Not exciting stuff, just things to watch when you’re bashing a kit…

TEBerg

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OK, I said I had tried some practice at using a Peel-Ply technique for finishing resin over fiberglass... Well, I like this technique very much!!! I’m very glad I did a search before starting the fiberglass work because this is so much cleaner than what I have tried before.

Here is a little review, please check out the other threads about using Peel-Ply (100% polyester material) they have great information.

The first photo is the top of the wing with the 3-inch fiberglass tape wetted and the polyester layered on top and also wetted out. Yes, I was a bit un-even with the edges and I had some “globs” out to the sides. Good thing is that I set boundaries with the blue tape just to keep any glue out of the flaps [smile]. The next photo shows half of the polyester peeled back off of the resin and fiberglass. This is really a nice smooth-texture finish!! You can see s couple small bubbles in the open fiberglass area where the two layers did not wet down together. Also, the sides feather out very nice. The next photo is the front of the wing with all the peel-ply off.

The 3-inch tape does have a little bit of an edge down one side from the manufacturing process. That leaves a small ridge, but not bad… I’ll have to check if anyone has had luck getting rid of this by sanding. I even thought of cutting off that thin edge before the layup, but did not want to risk making a big mess out of a little problem.

The fourth photo is the layup of the wing bottom. I used a very light mist of 3M77 spray (very light, 12-inches off the material, 1 pass) to help the fiberglass grab and smooth down. Also, notice I used a piece of lighter fiberglass that was 2.5-inches wide under the center tape to provide strength under the hold-down bolts. And again, blue tape to protect the flap area.

On the Sig Kobra building thread (Kit Building Forum) I posted some of the information from a little experiment to iron out wrinkles. The next two photos show the light weight fiberglass before and after ironing at 400-degrees. Remember to still test the material first, but what a difference to work with smooth pieces of fiberglass...

The last photo is looking at the final layup after I placed the fiberglass, wetted down the tape and spread a little (very little) resin over the sides, then placed the peel-ply and wetted it down. You can just see the lines I drew ½-inch outside the fiberglass tape to get a nice feather. Also, I went with a little LESS resin to start and did a little more work after to reduce the number of “blobs” on this side.

I didn’t get this posted until after lunch today – I had to go home at lunch and pull off the polyester layer (sorry, no photo)… This technique provides a VERY NICE finish!!!

You all have a good weekend, I have a float fly tomorrow and I have to call a local guy about cutting the vinyl graphics for this bird...

TEBerg

My Feedback: (1)

Just to continue on from the last post. I pulled the Peel-Ply off the bottom of the wing and boy is it NICE… The tape I used did have a little ridge down one side, and that leaves a bump down one side. I may still sand that down as part of the final sanding; I’m just worried about making a bigger mess than I start with [smile]…

Now, on with mounting the wing to the fuselage. This is not one of my most favorite parts because I measure, re-measure and then confirm and re-confirm what I’m about to do.. This is not a super hard task, but it still ends up taking me a whole day!!! Oh well, such is life...

Now, on with some specifics of the kit...

I did have a slight difference in the wing pannels. It looks like one outside wing rib was about 1/16th different than the other wing pannel. So, when I measured the wing center was just slightly off the glue joint. I went ahead and made some marks, square up the wing, and charge on… ***Edited - If you have the chance, you may want to check the kit plans and confirm how things line up before you build the panels.

OK for the 2nd photo I have the wing in the saddle and looking at the two slots for the wing hold-down dowels. The building manual calls to just drill the dowels in being careful to line up with the slotted plywood wing rib and then move on to drilling and installing the wing bolts. Back while I built the wing, I glued balsa blocks into the wing for the dowels. Because, with some “inconsistencies” in the plans and how I build, I know there was no way the slots in the wing ribs were going to line up with the slots in the fuselage former AND hold the wing on tight/straight.

So, per a suggestion from Sam, whose Skyraider has now been flying for years after a re-build, I glued plywood plates onto the back of the former and cut notches into the bottom front deck piece to make room. Then I drilled out the holes from the wing side and made them line up with the tops of the manufactured slots. After drilling the holes, I used a prop reamer to get nice clean and round ¼-inch holes.

Then I went back, re-measured and drilled and installed the wing hold-down bolts. I ended up drilling the holes about ¼-inch closer to the trailing edge from where I had originally marked the wing. This gave me a bit more “bite” into the block inside the fuselage (which I had glued some extra ¼-inch plywood). After the hold down-bolts were installed, I drilled through the front holes and into the balsa blocks inside the wing. The next photo shows a shot of the wing installed on the plane as the epoxy dries on the hold-down dowels. This photo does not have the former cut out for lowering the fuel tank yet. Before I glue the bottom front in place, I opened the former up about 1-inch lower to account for the engine mounting/carburetor placement. I also added a cross-support under the plywood hold-down dowel plates because I had chopped so much off the former.

The last photo shows the wing on the fuselage starting to look like an airplane… Please ignore the fact I still have to build an Entertainment Center for my wife and I just have an old door holding up the TV and stuff [laughing]…

Destroyer of Airplanes

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Tom,

Since my wings haven't been mounted yet I believe I'll use your method. While I have been waiting for your plans to get here I built the motor mount. I use this type of mount in all my planes it makes it very simple to set the down and right thrust. also it makes lining the motor up for a spinner super easy.

Destroyer of Airplanes

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I'm not sure how that second picture got in there, but here is the one I intended to post.

Paul[X(]

TEBerg

My Feedback: (1)

Paul,

That motor mount design is very simple and clean looking. Well, I should not say “simple.” Do you have a jig set up to cut the matching rings??

Using the electric motor sure does clean up the front of the airplane. She will look very sleek with no cylinder head or muffler sticking out…

Destroyer of Airplanes

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Tom.

I've done the engine mounts two ways. On my lathe or on the jigsaw. Both are easy to do. First I tape all the wood parts together and drill all the holes then shape or cut the outside, then shape the inside for airflow to what ever motor I have.

It really does make for a neat installation. The front nose box on the Skyraider engine looks quite the same as the front of the .60. My intention is to install a vacuuformed radial engine over the motor.

The picture that I didn't mean to send yesterday is a cowling that was from a gas powered bird. The holes are huge.

Paul

TEBerg

My Feedback: (1)

I have finished the tail feathers. Adding the counter balance to the elevator made some extra steps than those shown in the instructions. They just say to bevel the leading edge, drill holes for the connecting wire and then cut the slots for CA-type hinges. Also, the plans still show the elevator halves connected with ¼-inch dowel and the dowel is also included in the kit. Even though I will be using two elevator pushrods, just for the feeling of security, I decided to use the bent-wire between the elevator halves.

The first photo shows the elevator halves pinned in place with the counter balances and the wire is braced with a pine block while the Gorilla Glue dries. The second photo is a little closer shot of the right half and the metal ruler is just to help pin down the trailing edge. The trailing edge is shimmed or “packed up” with 1/8th thick plywood to center the elevator and counter balances.

Now, a story related to this from when I was learning to build. I was probably 10 years old and I was working on a pod-and-boom tow glider. It had a balsa frame fuselage/pod and the wings and tail surfaces had an air foil. Well, I was working on the vertical stabilizer and it had a tapered trailing edge. The instructions, which were just written in the corners of the plans, went something like this; “Glue the tapered trailing edge onto the vertical stabilizer frame while packing up the latter.”

Ok, so how would a young modeler know what “packing up” meant and how would he notice that “latter” was not something you would climb on. So, I thought about it for a while and glued it down with PACKING TAPE to hold the whole thing together!!! Needless to say I did not end up with a straight vertical stabilizer.

Buy the time my Dad got home, the airplane and plans were in the trash can and I wanted nothing to do with model airplanes any more. My father was such a great man and had been building for years. He reminded me of the time he was drying the silk on one of his planes over a gas stove and the entire thing went up in flames right in his hands. He missed not making that plane, because he had spent something like 50 cents on it and proceeded to cut new ribs from scrap material and finished the control-line plane. So, he brought the airplane (which had been gently laid on top of the trash bag) back into the house and we pinned the plans back down on the building board. He explained that “packing up” was to raise or shim up the tapered edge and the kit maker used the term latter to mean the last subject in the sentence…

What does this mean for this airplane – not much, just that if you do this modification I think that having the elevator taper symmetrical with the added counter balance may help.

However, this does mean a whole lot to me… Thirty-one years later and I clearly remember my dad helping me through questions like this. Hopefully it also reminds me to not “tell” my 12-year-old son he had better be getting his homework done and to help him work through the “little” things that may make a big difference..

OK, enough of that… Thanks for listening.

The next photo is a shot of the finished tail feathers. I marked the hinge locations last night in accordance with the locations of any doublers for the Robart hinges. Next I’ll drill the holes and counter sink the elevator and rudder holes after I bevel the edges, per the Robart example in the last photo.

Edited to add photos, took several tries to post.

TEBerg

My Feedback: (1)

I got some work done on getting some details set up. The first photo shows where I glued hardwood blocks on to the firewall at the locations where the cowl flaps stop and the top and bottom are flush with the fuselage. Also for extra cooling I decided to open the bottom of the firewall by cutting off the lower edge right in front of the oil cooler.

I also added some fill blocks to the leading edge of the wing and fuselage bottom just aft of the wing trailing edge. The plans show a straight line behind the oil cooler to the wing and the wing flush with the rear of the fuselage. However, with the wing dihedral there are gaps up front and the back of the wing hangs below the fuselage. Therefore, I wanted to try some filler blocks and see if it filled in the bottom to help with how flat a skyraider should be. The third photo shows the front and back (not the best for clarity, but you can get the idea) and the wing does “blend” in better with the fuselage.

Before I glued the front bottom section of the fuselage in place, I filled the corners where the sides meet the firewall. Because of the tabs and groves used in construction I have some little gaps that I did not care for. I mixed some epoxy with milled fiberglass and spread it into the corners (using blue tape to keep the critical areas clean for gluing the bottom in place). The fourth photo just shows where the glue/goop filled up the gaps. I figure it will help support against the engine vibration. After the bottom was glued in place I rough sanded the front of the fuselage and sanded the firewall edges to a taper where the cowl flaps are located. I left the little tongue from the fuselage side in tact just to keep that part of the structure a little stronger (5th photo).

Then I went on to some play time with the flaps and ailerons. I was not sure of the amount I needed to sand off (bevel) the flaps, so I drew a quick mock-up. The 6th photo shows the 3/32 thickness of the flap bottom sheet. Since I have installed the blocks/doublers for the hinges, I’m going to glue the hinges flush on top of the flap so the hinge point will be below the center-line. With this location, I need to bevel the bottom leading edge of the flap 9/32 towards the back and up from the bottom. This will give me 45-degrees of flap deflection.

For the ailerons, I drew the thickness and the centerline. The last photo shows the angle I need to get ¾-inch deflection from the aileron. This is a little more than the maximum 5/8 the instructions call for, but I figure the extra clearance won’t be bad. With that deflection I will need to bevel 1/8-inch off the top and bottom of the aileron to the centerline. It looks like an angel of about 22 degrees.

The really nice thing about doing this all first before I start drilling holes with the drill guide – I realized the hinge points will poke through the top of the aileron if I try to drill the hinges straight into the centerline. I lined things up and it looks like I can sand the top bevel first and then use that surface to guide/drill the hinges in parallel with the top starting at the center line. Based on recommendations from others on this site, I purchased the Robart hinge guide and it is much better than the old plastic one I have used on other hinges. I also grabbed my “quick release” drill bit and it makes a great grip for drilling the 1/8th inch holes.

OK, I’m off to watch other guys get to fly at the Fresno Warbird event tomorrow. Hopefully I can get the hinges drilled and surfaces beveled. Then I can start filling and sanding the bird [smile]...