An Aldij Reborn
This is the tail of my Aldij rising from the ashes.
What went wrong?
It was perfect day for flying the wind was blowing a steady SE and blue skys all round. Granted I was abit worse for wear from the night before. With my pass approved I packed my gear and headed off to Red Hill. I had recently redone the silicone hinges as the last few times I had flown, it had fluttered. Batteries had all been charged fully the night before.
Got to the cannon and conditions were ideal. Had one flight with the aldij without incident. I launched for second later in the afternoon and to join another aldij for some formation flying. On a slow left hand turn in the vicinity of the “white house” I experienced a doomed lock out. No control, no response and no hope of getting it back. The plane continued its slow left turn which progressively got faster and faster. Spiralling towards the valley below and eventually hitting the trees at what looked and sounded like “terminal” velocity.
After a long hike down and directions from the guys above at the cannon I finally found the wreck still lodged in the branches of a tree. I gathered up the pieces and made my way back up the hill. After double checking the voltage of the battery which was still full we concluded that is would have to have been the DSM2. This has not been the first lockout I have had with DSM2 on the slope. Most of the time they are brief and I get control back. These usually occur in foamy’s with those colour receivers in them. But this was a genuine Spektrum full range receiver and satellite??
Can it be salvaged?
So looking over the wreck all the guys are speculating what can be salvaged. As you can see from the “before” picture above there was not much there. Basically both tails were trashed. The left wing panel was ripped up and badly delaminated. Same goes for the centre panel. The fuzz, was ok. Was never in great condition to start. The nose cone however had some damage which was easily repairable. The right wing panel was ok some very minor damage. But still useless on its own. So all I really had was an old aldij fuselage. I now need to find a new wing and tail feathers. Easier finding hens teeth if you ask me.
Moving on and rallying the troops
A couple of weeks later we had the PSS at Chappies. I had been chatting to a couple of guys in the club and a few were interested in building some aldij wings and tails. As it happens Tim WB had a fuselage he was given. Dave was also keen as he was building a new aldij and wanted a spare set of wings. Ryan was keen but Christo volunteered to help him repair his wing.
So there were three. Three eager guys wanting to build. All we needed now was someone to show us how. A master of the art of wing building. This could only be Hans.
A couple of weeks later we had the PSS at Chappies and that gave me a chance to chat to Hans about running a workshop to build our wings. Without any hesitation he agreed! Hans setup a strict timeline and itemised everything we had to complete each night. We all decided Friday nights would work best, as we’d be driving through to Stellenbosch. The fee for each night you ask? Just bring Pizza and Beer!
It looked impossible, but Hans was confident we could do it. 3 aldij wings, 3 aldij tails in 3 nights!
This is probably one of the most important parts. Being prepared means things go smoothly on the night of the build. Hans sent us a shopping list and each of us were allocated a bunch of items to purchase. Dave bought all the composite materials after multiple trips to AMT. I bought all the brass tubes, piano wire, paint and other bits and bobs from the hobby shops. Tim WB sourced the isoboard.
TIP: We learnt towards the end of this build that prep work up front really helps.
Build Night 1
Started with usual taking shop and getting to know our way around Hans garage. Followed by some pizza and beer. First on list was cutting the cores. This involved cutting up the iso board into the individual blocks. 5 for each wing. This is where our major bit of scope creep came in. We saw that there was enough isoboard to essentially cut 2 sets of cores each. Collectively we thought this would be a great idea. In hindsight not so much. The first sets were all demonstrated and cut by the skill full hands of the expert, Hans. The second sets were given to us to cut on our own. This was great for learning but took much longer than expected. We all ended up messing up one panel. Because of the delay not all the tip panels were cut. These involved a built in 2 degrees of dihedral as per the aldij spec. Tim WB took the remaining panels home to cut later.
Also cut out on the night were the wing and tail mylars. These needed to be taken home for waxing and spraying homework. I agreed that I would source the 2K paint and spray all the mylars.
It was agreed that we would bag one wing and the three tails on the second build night the following Friday.
Daves wing was singled out to go first as he wanted a plain white top wing and white strips with black carbon exposed on the bottom. So over a few nights during the week I sprayed up all three sets of tail mylars in various colours using a 22L compressor and an airbrush. The wing mylars were definitely tougher as I had a spray gun, but it was way too big for this job. The airbrush was also too small. A touch up spray gun would have been perfect. In the end I used the airbrush and opened the taps full. It worked but just took a lot longer to get the coverage.
Build Night 2
Now to cut some cloth, mix up epoxy and bag.
All the prep work probably took the longest. This involved using contact adhesive spray and baking paper to keep the cloth together while cutting and handling. All it entails is spraying a fine mist of adhesive onto the cloth and rolling the baking paper over the sticky area. Once that is done you can trace out you wings using the wing mylars. This is done on the bias (at 45 degrees). This gives the wing its torsional strength (no twisting).
We had 4 panels of 200g carbon to cut for the one wing. Because of the width of the cloth we could not fit the whole wing in and therefore needed 2 panels per side. This meant we would have some overlap in the centre of the wing, which would also provide some more strength.
TIP: Always roll up your cloth. Don’t fold! Store your cloth rolled up.
We then needed to do the same for the unicarbon cloth. But this time we needed to cut with the ribbons, meaning we could fit the whole wing in one panel. So two of these needed to be cut.
Next was the kevlar hinges. Again these need to be cut along the bias (at 45 degrees). They were around 5cm wide and as long as they could be given the size of the cloth.
TIP: Have a separate set of old scissors for cutting kevlar. Be prepared to sharpen these often. Hans had a sander handy to sharpen his set.
The foam cores had be bonded together (UHU Por glue), sanded lightly, LE cut 1cm off and TE trimmed straight. We mixed up about 100g of epoxy at a time and poured onto a paper plate for Hans. He used a small foam roller to paint the epoxy onto the painted mylars. NB: be careful if the epoxy is not fresh and some what sticky it could pull up the paint on the mylars. Once the mylar is coated place the first layer of carbon weave down. Now wet with good amount with epoxy and roll out with a small hard steel roller.
TIP: You will have to manufacture one of these steel rollers use a small paint roller and some turned steel. But is is a critical step to reduce pin holes in the finished product.
We continued this for all three panels on each side of the wing. 2 x carbon weave and 1 x unicarbon.
Now we placed the bottom panel in the cut foam re-leafs (all taped together) and placed the cores on top. Making sure everything is aligned correctly. We then proceeded to mix up some spar bond and added some black pigment. This was then placed in a bag and piped onto the leading edge which fills the 1cm gap where you cut the foam away. The top panel is now carefully flipped and placed on top to sandwich the core. This is now ready to go in the bag.
The tails were done with an extra strip of kevlar on the LE and the rest was all kevlar top and bottom. They were done in one piece and cut at 110 degrees later.
Build Night 3
During this night all the cutting prep was done during the week so we just had to bag Tim and my wings. This all went fairly smoothly as you can see for the timelapse of Tims wing in the video above.
The Days and Nights After
The next day I went through to Stellenbosch to pick up our freshly baked wings. Wow what a great feeling it is to unbag and pull the mylar off your creation. All glossy and new!
First I marked out everything with masking tape. Measured over and over again to make sure I had got it right. I then managed to get hold of some diamond dremel disks from Tim. I taped a long piece of alu straight to the wing and cut the TE. Next I started to sand the LE while the wing was in one piece. This was a rough sand using a belt sander.
Then I used a saw and cut the wing into its three panels. I also made a long sanding block about 40cm long and 10cm wide and stuck 100 grit sandpaper to it with double side carpet tape. I used this to finish of the LE’s on all the panels. Keep checking that your LE line up with each other. I found some gaps in the spar bond so had to mix up some more as filler and left overnight to cure. Man that stuff goes hard! Also sand you 2 degrees dihedral into the outer wing panels.
TIP: Use a diamond disk to cut carbon.
TIP: Use a long sanding block with sand paper stuck on with double sided carpet tape. Available at most hardware stores.
Next I had marked out all my control surfaces. For the top hinge I used the standard dremel cutting disk and taped a long steel ruler along the hinge line. I just hold the disk in my hand and run it along the ruler over and over again until I hit the kevlar hinge layer below the carbon. On the bottom I use the dremel with the diamond disk and steel ruler taped down to cut out a 2mm gap in front of the hinge line. I used an old credit or gift card with sand paper stuck to it with double side carpet tape again to sand open the area where the control surface tucks into. Then crack the hinge and start to loosen up the hinge.
Now join the wings again. I used brass tubes with thick piano wire (about 7mm). The piano wire was abit thick so had to use a drill and sand paper to make it fit. I also made a foam cutting tool to cut the holes in the foam where the brass tubes go in. I lined everything up on the bench using lines I had pre drawn. This helped keep the cutting tool going off at the wrong angle. Once the holes are cut make sure you scrap away all the foam from the carbon skins top and bottom. This gives the epoxy micro ballon mix something to bond to. Keep the brass tubes in one piece. In this case 16cm long (8cm in each wing panel). Tape up each side of the tube so you dont get epoxy inside. Tape up the wing to protect it for all the mess. Fill the holes with a thick epoxy and micro ballon mix. I added black pigment to mine, but really not necessary. No stick the brass tubes in and join the two panels together. Lots of epoxy will ooze out but that normal. Clean, wipe and tape up the join. Make sure you set it at the 2 degrees dihedral required. Now leave it to set over night. I did mine over two nights instead of all in one go.
I then needed to drill my wing bolt holes. This was tricky because I didnt have a drill press. But eyed it out and it worked. I measured this a couple of times before drilling. Making sure I had distance from the end of the tail boom to the wing tips. I made some sharp tipped threaded bolts which I screwed in the fuz. Leaving the sharp tip sticking up. I then placed the wing ontop and lined everything up. Once I was happy I pressed down hard on the wing marking on the masking tape where I needed to drill.
Next I cut my tail in half and sanded to the 110 degree angle for the vtail. I also built a correx jig to leave it to set in. I also cut the hinges using the same method as above. I cut some light glass strips for the joint and left over night to set. I cut a slot in the tail for the Vtail to fit in and 10min expoxied it in. This way it will break away in a crash.
I purchased some new GWS servos for the flap and ailerons. The tail servos were still good. Acquired a new DSMX 6 channel full range receiver with sat. Plus it worked with my Telemetry module. I also bought a Life battery so I can fly for longer and it handle the high amp draw.
The Re Maiden
The day was a perfect SE at Red Hill. The guys were flying up at the cannon and Mally had put up his Aldij already. The first toss out was perfect one or two clicks of trim and she flew like on rails. Two spectacular flights followed that afternoon. Subsequently I have had one mishap on a landing with a tree. Folding the Vtail. But one night of repair and she looks like new. I have also ballasted up one of the two ballast tubes with 360grams of lead. Bringing it’s AUW to just over 2.5kgs. The aldij really loves the weight and flys faster and climbs better with it.
Thanks to Dylan at AFC who originally owned this Aldij and sold it to me. I bet you wish you had it back now
A HUGE thanks to Hans for the help. Without you this would not have happended.
Ryan and John for helping repair and spray my fuz.
Thanks to my fellow builders, Tim and Dave. We sure learnt alot during this process. Hopefully we’ll see your Aldijs up soon?