Up On All Threes

A momentous day for the Sling project. Thanks to my new neighbor Mike (literally I just met him) for gathering the crew to flip the plane over on it’s wheels. After a short briefing on what was needed to be done and where not to hold the plane we all made short work of carrying the fuselage out of the garage and flipping over onto it’s wheels in the driveway. What a HUGE relief that nothing was damaged. I was so stressed that we were going to drop it that I was actually shaking.

I added a weight to the front of around 30-40 lbs just to make it easier to move if needed (not having to worry if the tail is going to hit the ground). There’s also a saw horse in the back so if I put some weight on it while I’m working nothing will move. OK now lots to do… need to order some stuff… wait I need money first 🙂

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Finishing Up Seats

Time: 1.5 hrs

Just painted the remaining parts of the front and rear seats that I had not painted because I needed parts to put them together. I did one coat of gray paint and will need to do a light sanding and do a second coat in a day or two. I’ve learned my lesson when the spray can says recoat after 48 hours it means after 48 hours :-). Last time I waited a day and figured that was good enough, well the paint crazed and I had to sand it down to the metal, so I will wait. M hoping this weekend I will get enough people together to roll the plane over onto its wheels. There a lot of work to be done and I’m in a holding pattern now until I flip it back over. 

Just one thing to note on the paint. I had used Rustoleum Dark Machine Gray and the paint absolutely sucks. I moved to Krylon Dark Machine Gray and the paint is awesome. Unfortunately it doesn’t exactly match the Rustoleum so I need to finish out the painting of the seats with the Rustoleum paint. I used the Krylon on the nose wheel strut and other undercarriage parts and love the paint. 

Yesterday I met with Jean and Torrance TAF and we were looking at interior options. I may end up getting a custom leather done. I really want to do a Black and Tan interior and they don’t really offer that, but I’ll see what the factory comes back with. 

Bottom Fuselage Rivet Sanding and Main Wheels

Time: 5hrs

Today I sanded the bottom fuselage rivets. I used the same procedure as the other times, except this time I went back and sanded all the rivets with 800 grit paper which took out the scratches left by the 240 grit paper. I’ll probably go back and do this to the other areas of the fuselage as well. It’s pretty quick, but I’ll need to get a bunch more done scs because they don’t last very long. 


A little hard to see from the photo. The rivet to the right has been cleaned up with 800 grit light sanding while the one on the left was only sanded with the 240 grit. This probably isn’t necessary, I’m sure the paint would fill the fine scratch left by the 240, but it makes me feel better :-). 

I also mounted the wheels on the main gear. Pretty easy except the cotter pin wouldn’t go in on one side. I didn’t bend the pins yet just in case I need to pull the wheels off. I used the grease that came with the kit to grease the two bearings and the nut was tightened just enough so there is no play in the wheel. 


Grease on the inner bearing. Same done to the putter bearing. 



Close up of the mounted wheel. 

Ok so now I just need to get about 5 people together to lift this thing and spin it over on its wheels. I don’t think my jacket rotisserie invention will jack the plane high enough to spin it and I don’t think the garage is high enough either so we’ll have to walk it out and the spin it in the driveway. Should be fun. 

Bottom Fuselage Rivets Filled

Time: 2.25 hrs

Today I riveted the main gear channel skin and filled the bottom fuselage rivets. Nothing really interesting to mention, maybe just that the main gear bolts were torqued to 62ft lbs (84Nm). They are M10 Class 12.9 bolts and from what I could find the dry torque value is around 62 ft lbs.

NOTE (01/18/2018): Another builder has verified with multiple sources from TAF SA that the gear bolts should be torqued to only 18ft lbs (24Nm)

Rivets filled

Main gear channel skin. Doesn’t look so pretty with the plastic still on it. It’s a little difficult to see, but I put the front edge under the other skin and the rear edge over the back skin. Make sure to torque the gear bolts before riveting this on; reason one is the the bolts pull the gear channel in so the skin will bow out if you rivet it first, second the rivet ends get in the way of the nuts so you can’t really tighten them. You might be able to get a box wrench on it, but definitely not a socket wrench.

So now I just need to sand the rivets and put the wheels one, then it can be turned back over and put on it’s wheels.

Main Gear Mounted

Time: 2hrs

Well I guess a day makes a big difference. After failing to get the bolts installed a few days ago I had much better success today. I used a little different technic then previous and maybe this the reason for the better outcome. I started by lining up the gear the best I could and then checking the alignment of the metal spacer and hole in the gear channel. Once it was close I used a large punch in the hole and pushed it into the hole using wood as a pry bar against the main spar. Now rather the clamp that in place I did the same on the other side. Once both punches were in place I then clamped the gear in place. I removed the punches and used a small half round file to file down any burrs in the hole. Starting on one side I inserted one bolt, pushed it as far as I could by hand (which was only about 1/4″ – 1/2″ and then used the wood to slowly pry on it. To my surprise the bolt slowly moved in. I was able to pry it in until it hit the other side of the gear channel. Then I had to tap in it with a mallet. Now on to the other side. Same method and the bolt went right in. Prying the bolts in was the same as what I tried to do the other day, but bolts just wouldn’t budge. It must have been the tecnique of using the punches to line things up first that really helped. The next set of bolts went in using the same method. I’m so happy that this worked out. I was so frustrated the other day and just couldn’t see how this was going to work, but I guess a small change in process did the trick.


Using the main spar and a long piece of wood to put pressure on the bolt to push it in. It didn’t require too much pressure, but I would have never been able to push them in by hand. Note: I flipped this image so that it’s a little easier to see where things are. I’m actually working upside down)


Bolt on the left and one on the right are in… making progress.


The tool that saved the day. I used one on each side to line the gear up.

So next is to rivet the gear channel skin then fill and sand the bottom fuselage rivets.

Main Gear Mounting

Time: 6hrs

Well this has been very challenging. I think mounting the gear with the fuselage upside down was a good decision. It’s been very easy to check the fitment of the gear and accessing the bolts has been somewhat easy… though working inside the fuselage is a bit of a pain and somewhat cramped. The main issue is that I can’t seem to get two bolts (one on each side) in at the same time. Once I put one bolt in then the other side is a fraction of a millimeter off which makes it impossible to push the other bolt in. There is really no room to tap the bolt with a mallet. I did find a way to push the bolt in using a piece of wood placed between the bolt head and the main spar. After some research in the manual it appears that the bolts are to be installed with the head facing aft, but that’s not what the FAA says. I’d really like to install them in the correct orientation. 

As far as fitment I’ve had the gear on and off a multitude of times. The top of the gear hits the rivnuts and also interferes with the rivets that will be installed to hold the rear seat floor panels on. Also the gear is a bit too wide at the bolt locations so that needs to be sanded down as well. 

Some photos and a bit more narrative below. Even after working in this for many hours I have not yet been able to get the bolts in… so the work will continue. 


This was a good method for me to allow placement and rough fitting of the gear. You can remove the wood block and check the fitment and then sand as needed. 


Here I thought I had the fitment right so I put some grease at the bolt area location as instructed by Jean from Torrance TAF. He said that this will minimize any creaking in the gear. It turned out that the top of the gear needed to be sanded as well so the gear was removed and sanded multiple times since this photo. 


I put a bevel on the top edge of the gear. This was done to get the gear to fit down without putting pressure on the rivnuts. Also it helped give some room to where the rivets will be installed for the rear floor panels. After this photo was taken I ended up taking out the belt sander with some 60 grit paper and sanded down the bevels even more. 

I think the fitments is good now and the gear seems to fit down into the channel without needed to be held into that position. This may help with the installation of the bolts which so far has been impossible to do. I spent nearly 4 hours trying to get two bolts in. The first bolt is fairly easy to install since you can get perfect alignment of the metal spacer in the gear and the holes in the gear channel so the bolt can be pushed in by hand or by using some wood to pry it in. The problem is the insertion of a second bolt on the other side. The top to bottom alignment can be tuned by pushing down on the gear and holding it with some clamps. The left to right positioning is really the problem. There’s not too much you can do about it and even if you have a small misalignment the bolt will not go in. I have tried to round off the edges of the metal spacers in the gear so that there are no hard edges for the bolt to catch on, but it only helps minimally. I’m thinking I may need to widen the hole in the gear channel just a small bit to get the bolts to fit. If you had room to tap the bolt in it would probably go, but there really isn’t much room. Hopefully I’ll get some time to work on this again in the next few days. 

Sling Inverted

Not really work done on the plane, but a monumental achievement none the less. Through some ingenuity I was able to roll the plane over any raise it up to put it in the saw horses. A previous failed attempt at lifting it with my wife and daughters had me fairly distraught. I managed to come up with a somewhat crude system not only to raise/lower the fuselage but also rotate it all on my own. I think it only cost me about $150 with the farm jacks taking most of the cost. It should come in handy rolling back over with the gear attached as well.

In any case I’m glad I got this done. Now I just need the fill the rivets and mount the gear.

Flipped upside down and on the saw horses.

I was a bit skeptical of my mechanical engineering skills so I made sure to have some ropes strung up just in case something failed.


Rear mount. I need to swap the lag bolts in the plywood that mount the cut down inch post with carriage bolts that go all the way through. Even though the lag bolts seemed to hold ok I’m nervous that they’re going pull out of the wood the next time. For mounting the plywood to the 2×4 I used 2″ lag bolts on the top and 4″ ones on the bottom through the 2×4 spacer.


On the front I just used some long carriage bolts and large washers through the engine mount. You can also see the 1.5″ EMT conduit attached to the farm jack. The black part that the tubing fits into is a cut off 3″ fence post. All parts curtesy of Home Depot… well I got the farm jacks from Harbor Freight.


The rear jack was a bit different. I didn’t have enough room in the garage to put it in line so I had to mount the tube sideways. There’s a piece of steel bar underneath the tubing clamps and two clamps (you can only see one) on the right side. I’m surprised at how solid the tubing is on the jack I was thinking I was going to have a lot of problems with it wanting to move side to side.