Originally Posted by b0Bro's dad

CG calculation spreadsheet for those that are interested.

Far out thats full on calcs,

lol thanks stu, i am a little keen to get her in the air now...

Dear Byron,

If there is one thing I hope to have taught you (apart from never buy cheap tools), it is to do your best in all things. I was proud of your first place in your last competition, and prouder still that you have been bumped up a class where the trophies will be harder to earn. Your new plane will be finished when I'm satisfied that I have done the best job I can....and hopefully that will be before Bendigo.

Things still to do:
- fit the canopy
- complete the wiring
- fit two more cooling baffles under the canisters
- install the fuel plumbing
- build up the diameter of, and fit the tail tubes and locking nuts
- fit all the control horns
- locate and drill holes for, and fit the rudder cables
- fit the nylon bushes and carbon hinges on all surfaces
- fit the control linkages and program servos for desired control throws
- fit baffling into the cowling
- do a final CG calc and adjust CG as necessary
- wet sand and polish out all of the paint 'masking ridges'
- run in the engine
- get a CofA
- and last but not least, talk Tony into doing the test flying

Sadly Stu, I suspect that list might take more than a couple of days to complete.

Cheers,
Ian

I acknowledge that I haven't been as active on the build thread as I'd like, but I have a family and friends who were getting a bit jealous of the time I was devoting to Byron's plane and demanded their fair share! I haven't been totally idle, however, and I have now completed the cone.

From the CofG calculations, and a decision to fit the extra two servos in the tail, I knew that I needed to fit all three batteries as far forward as possible. I therefore removed the battery box built to hold the Relion 2600 Ah ignition battery, and constructed a new battery box to hold the two Relion 5200 Ah flight batteries as well. As before, the battery box was constructed of 3mm birch ply and lined with 5mm foam rubber around and between the batteries to isolate them as much as possible from vibration. The box was screwed onto the firewall with 6 x 18mm brass wood screws and the batteries were retained with a velcro strap.

I moved the ignition 20mm higher to releive some strain on the high tension lead to the left cylinder which also required me to move the hole for the ignition wiring and reinstalled the grommet to prevent chafing. I removed the Smart-fly engine cutoff and reinstalled it across the top rear of the cone to keep the 'ignition stuff' on the right and separate from the 'radio stuff' on the left. This change also provided a neater wiring solution all round.

Byron wanted all of the electrical connections between the cone and the fuselage to be accessable on the 'outside' of the cone so I drilled two 25mm holes on each side and fitted them with grommets. The last hole was drilled at the front top of the cone and fitted with a grommet for the hall sender cable.

I was bit worried that the 3mm tap washers I had used to damp some of the engine vibration might crack under repeated use so I made up some engine vibration dampers from 6mm heavy duty 'laminated' rubber which were used to space the engine mounting plate from the firewall. I used large diameter washers and spring washers, held in place with a generous application of Locktite, to secure the engine onto the cone.

I needed to extend a few leads and shorten others to make sure all the connections fitted on the outside of the cone between the two wiring holes. I fitted three Ernst battery charging plugs in the fuselage on each side of the Emcotec and made up the extension leads for the 2 x flight batteries and the 3 x battery charging leads. Making the extensions for the battery charging leads was interesting because it was the first time I had made servo plugs using the connectors and special crimping tool (which after much searching I eventually found at Taits Hobbies in Geelong).

At this point, I spiral wrapped all of the cables and worked out the positions for the cable tie anchors which were epoxied in place in the cone and forward fuselage. When the epoxy was dry, I used 2mm cable ties to hold all the cables in their pre-determined positions, being careful to ensure that the battery cables were not 'anchored' in a way that would prevent the easy removal of the batteries for charging or maintenance.

As soon as I've finished tidying up the cables in the fuselage and fitted the fuel tank plumbing, I'll attach the cone to the fuselage connect up the cannisters and Locktite all the attachment bolts .

I prommised Byron that I'd have his plane ready for the first engine run when he comes up to Sydney for the weekend. That meant that I needed to finish the fuselage wiring and fit the fuel tank before fixing the cone and connecting it all up.

The wiring was almost complete and just needed some anchor points to be epoxied in place and the wiring to be bundled and held neatly in place with some cable ties.

The fuel tank was a little bit more fiddly. I had already assembled the tank so I just need to confirm which outlet was which (and marked so I couldn't get it wrong later), cut the tygon tube to length and secured it in place with 2mm cable ties. I used 2 x 4mm cable ties to secure the tank into it's mount.

I toyed with the idea of making a join in the main engine feed line at the cone but eventually decided that a continuous fuel feed line minimised the chance of leaks and something coming adrift in flight. I drilled the cone in front of the engine servos to take the fuel feed line from the carburetter into the cone, and epoxied a clamp at the rear of the cone to line up with the guide in the fuselage.

I wrapped the fuel vent line around the tank to prevent it venting fuel during extreme manouevres and held it in place with cable ties, before I drilled another hole in the fuselage floor in front of the undercarriage to carry the vent outside the fuselage. I used more cable ties and silicone to secure the vent line away from the cannisters.

I used the securing ring to mark the cutout for the fuel dot and used the dremal to enlarge the pilot drill hole. I mounted the fuel dot with the supplied screws and connected up the fuel filler line, again using cable ties to secure the tygon over the fuel nipple.

Finally, I slid the cannisters into place and fitted the cone to the fuselage. I connected up the cannisters and threaded the fuel feed line through the hole in the cone and secured it to the carburetter with another cable tie. Last, it was simply a matter of feeding the cabling through the grommets in the cone and making all the connections. I was pleasantly surprised to find that this bit worked just as advertised.

Job done.

I'd been puting the canopy off as long as I could but eventually I knew I'd have to tackle the hard bits!!

First, I made sure that I had a nice warm day to keep the new canopy flexible. I covered the old split canopy, that I had previously cut to shape, with glad wrap and nested it inside the new canopy to mark the cut lines with a non-permanent marker pen. It was a simple matter to carefully cut the canopy to shape with a pair of heavy heavy shears. At this point, I also covered the new canopy with glad wrap to protect against any scratches.

The big issue with gluing a canopy is getting it straight as any warps built into the canopy frame at this stage will be there forever. The best way to do this is with the frame fitted to the fuselage but that makes it almost impossible to hold the canopy tight against the frame while the glue dries. The next best method I've seen requires the manufacture of a false floor to mimic the fuselage. I constructed my false floor from 3.5mm ply using the fuselage as the the pattern to get all of the mounting cut-outs exactly right. When I was happy that I had an accurate representation of the fuselage, I stiffened the false floor with three 6mm batterns.

I mounted the canopy frame on the false floor and pinned it in place with four mounting bolts before very carefully inserting the canopy from the underside-rear. This was a delicate operation as I had to feed the front lip over the instrument panel and under the frame at the front while gently easing the canopy forward and making sure I didn't scratch it. I was very thankful that I hadn't glued the instrument panel in place as the extra freedom was really needed.

Next up was the fun bit of blowing up lots of balloons to hold the canopy tight against the canopy frame. Byron helped here and the extra set of hands was almost essential. We quickly discovered that lots of very small (low inflation) balloons were better that a couple of bigger ones and that stuffing balloons into an enclosed space is not the easiest thing to do. We persisted and finally got the space full before we closed off the open back with a couple of pieces of packing tape.

When I was happy that everything was sitting right, I worked my way around the frame, easing the canopy away from the frame to squirt Pacer 'Formula 560 Canopy Glue' into the gap. I used a wet paper towel to clean off the excess glue (not too wet and not to fastidious as this glue can be cleaned off when dry) and set the whole thing aside for 12 hrs to dry.

The next day, I removed the false floor and fitted the canopy assemby to the fuselage and found I had induced a very slight twist (bummer). Fortunately glue was still damp enough for me to lift part of the canopy away from the frame to remove the twist and re-glue. I used 12mm square balsa packing and spring clamps at to reseal the bits I had re-glued and set it all aside for 5 days to cure properly. When the glue was dry, I mixed a thick paste of epoxy and micro-balloons and sealed the inside edge of the canopy before setting it aside for another 24 hours to dry.

When all the glue was dry, I spent a couple of hours using Brasso to polish the excess glue off the canopy and get that perfect 'crystal clear' finish. All that was left was to epoxy the instrument panel and pilot assembly in place. I have to say, that it all looks pretty good to me

While the canopy glue was drying, Byron and I fitted the pull-pull rudder system. This was 90% measuring and 10% doing but the results speak for themselves.

We started by using a square across the top of the fuselage and a steel ruler to accurately measure the depth to the centre of the arms on the rudder tray. These measurements were transferred to the outside of the fuselage and marked with a non-permanent marker pen. We temp fitted the rudder and measured the height of the centre of the rudder arms which was also transferred onto the fuselage side and marked. We then used a 1.5 metre length of 3mm carbon tube as a ruler to draw a line on the fuselage between the front and rear marks. This line showed the level for the cable exits.

Next we had to work out exactly where along the 'level' line we need to cut the line exit holes. We started by accurately measuring the width of the centre of the wire leads from the rudder tray. We found this to be wider than the width of the arms on the rudder so we pulled out the rudder tray and moved the wire leads in so they matched the width of those on the rudder. When we were happy, we marked the width exactly on the underside of the fuselage and used the carbon rod to connect between this point and the centre of the wire leads on the rudder, making sure to 'cross' the wires. While Byron held it all steady, I used my calibrated eyeball to mark where the rod crossed the fuselage sides.

We marked each side separately and took the average of each mark to mark the drill hole for one side only. I used a 3mm drill and a fine round rat file to gently open the hole and bore through the fuselage former, using the lines marked on the bottom of the fuselage to get the angle right. When I had cut a basic hole, we temp threaded some trace wire and tightened it to see where it touched the hole. I needed to enlarge the hole slightly to the rear until the wire was properly centred (not touching the sides) and then enlarged the hole with the rat file to fit a 4mm nyrod inner 'fairlead' to prevent the wires from chaffing. We rethreaded the wire through the nyrod fairlead for a final check before repeating the exercise on the other side.

When we were happy that everything was lined up correctly, I mixed a thick paste of epoxy and micro-balloons, tensioned the wires and epoxied the nyrod fairleads in place. When that was dry, I epoxied a pair of metal exit covers in place to tidy it all up. Job well done.

Hi Ian,

Can you post the dimension for the rudder pull pull exits on the sides of the fuseloge? Please use the rudder hinge line as a reference. That will help me locate the exits on my 260.


Cheers,

Michael Wyman
Gilbert Arizona
AMA L-777
IMAC 777

Can you post the dimension for the rudder pull pull exits on the sides of the fuseloge? Please use the rudder hinge line as a reference. That will help me locate the exits on my 260.

Michael,

My exits ended up at 220mm forward of the rudder hinge line and 55mm up from the bottom of the fuselage at that point. Please note, however, that these figures will only be accurate if you plan to cross your cables, have your rudder tray in the same place as mine and use 45mm servo arms.

Hope that helps,
Ian

Contrary to all impressions, I havn't been completey idle over the last two weeks and I have made some significant progress towards finishing Byron's model. I plan to bring it down to Melbourne for the handover ceremony at Easter so I now have a hard target for practical completion (Byron will still have to run in the engine, balance all the servos and adjust the throws).

A major hold-up has been getting the ignition system to work properly. Try as we might we couldn't get the original one to arm and I finally ended up ordering a replacement from 3W. Ernie was great and had the new ignition to me by overnight mail but for some reason I couldn't get the LED's on the new one to work properly. After much angst and some detective work with the voltmeter, I eventually worked out that 3W had installed the ignition LED lead backwards and all I needed to do was reverse the LED plug. Everything in the ignition system now works as advertised.

While I had the cone off, I decided that the 6mm rubber stand-offs I was using pushed the engine too far forward. I found some 3mm fabric reinforced rubber sheet at Clark Rubber and made up some new stand-offs. On each bolt, there is now a 3mm rubber 'washer' between the engine plate and the firewall, and another one inside the firewall before the steel washer, spring washer and locktighted retaining nut. The engine feels nice and rigid but I'm hoping the rubber will help with damping engine vibration as well.

The next job I had to tackle was to increase the diameter of the tail joiners. I believe that later models have 19mm ID fibreglass tubes built into the fuselage and stab halves which is a nice tight fit on the supplied 19mm OD aluminium joiners. But for some strange reason (??) my model was built with 20mm ID fibreglass tubes which are a very loose fit for the 19mm joiners. I searched the net for 20mm OD carbon tube but the closest stock item I could find was 20.8mm OD. I therefore took a deep breath and made up a fairly thick mix of epoxy and micro balloons which I 'painted' over the 19mm replacement carbon tubes. I rotated the tubes every hour or so until the epoxy started to set which was reasonably effective in stopping gravity from building up the epoxy on one side. When it was dry, I used 150 grit carbonium paper to carefully hand sand each tube, trying to take the epoxy/micro balloons material evenly and testing the fit a lot. This process, although a pain in the #%%$#@ worked pretty well and the tail is now a nice firm fit. the joiners are, however, noticably heavier than they were (but still lighter than the supplied aluminium joiners). As an after thought I wrote to PCB in New Zealand and asked if they could supply non-standard 20mm OD carbon tube and they replied yesterday that they could get me a special order of 19.9mm OD tubes in the lengths I required in about three weeks. I've ordered a pair.

Other carbon problems emerged around the supplied 1.8mm steel hinge rods. I'm hearing that people who have used the steel hinges are getting significant elongation (chewing) of the phenolic, particularly on the rudder. The standard answer seems to be to replace the 1.8mm steel hinge pins with 'thin' 2mm carbon rod and install 2mm mini-bearings in the fuselage/stabs/wings. Unfortunately, 2mm bearings from Miniture Bearings Australia (part number 682A-ZZS-ECO) cost A$12.30 ea plus postage. Cheaper options are 2mm sintered brass flanged bushes (part number BF00200-0400-0040-SB) at A$5.28 ea or 3mm plastic flanged bushes (part number BF00300-00450-0020-G) at A$5.15 ea. Before I went down this path, however, I needed to find 1.5m lengths of 2mm carbon rod/3mm carbon tube for the aileron hinge pins and I couldn't find these in Australia. I did find the long lengths as stock items in UK at www.carbonology.com but the $100 plus delivery fee made these very expensive. I purchased 3 x 1.5m x 3mm tubes and 4 x 1.5m x 2mm rods plus all the 1 m lengths I needed to make the delivery cost worthwile.

I spoke to Barry Fox this morning about best method of doing the hinging and he suggested I check all my 2mm rod with a vernier, find a slightly undersize rod and use fine sandpaper to make it fit. The alternative is for me to try and 'push out' the peices of 3mm OD nyrod inner that XTreme Composites have glued into the rudder/elevators/ailerons as bushes for the 1.8mm steel pins, and use 3mm carbon tube hinge pins making sure that the carbon rotates WITH the control surface (and INSIDE the plastic bush) by fixing a small flange to each control surface. I might try method one first on the grounds that if it doesn't work I can still try method two but both will be tricky. All I can say to XTreme Composites (if they are listening) is they really need to fix this design flaw!!!

Apart from that, I have started to wire the wings and tail using heavy duty twisted wire from Air Wild. I have made up fixed Multiplex 6 pin connectors for the wings and (because I can't get into the tail to bolt the 6 pin Multiplex connector in place) 3 pin Deans connectors for the tail. I've also puchased the Air Wild 4-40 heavy duty wire connector to connect the pull pull wire to a 4-40 ball link on the rudder. I've silver soldered a small brass ferule onto each wire and pulled them into the Air Wild connectors for a very neat and almost indestructable fit.

A few random photos are attached.

Why do the fiddly bits take so long to complete?? I set myself the goal this weekend to complete the wiring which I finally managed at 10:00pm on Sunday night .

I fitted two Multiplex 6 pin connectors to the left side fuselage to mirror the right side I had completed the day before. When the Multiplex connectors were fitted, I measured and cut the servo leads leaving the male JR plugs to connect into the Emcotec. Soldering the leads to the Multiplex's was fairly straightforward; I just had to be careful not to use too much heat, make sure I fitted heatshrink tubes to each wire before I soldered it to the plug and get the colours lined up correctly. Fitting the Multiplex connectors into the wings was more difficult as I only had a short wire to work with and I had to ensure the colours matched properly. I tested each plug as I went, to ensure I had a proper connection to each servo.

The tail wiring was a pain. I had decided to use 3 pin Deans connectors for the elevator servos, mainly because I couldn't get into the tail to fit Multiplex 6 pin connectors. The Deans are gold plated for minimum resistance and are solid enough handle repeated assembly/disassembly. They are also idiot proof in that they only connect one way. I started by marking the location of the wiring exits (45mm in front of the front face of the forward tube) and drilling 3mm pilot holes. I finished the holes with a round file to fit 10mm grommets (big enough for double wires and small enough that the Deans plugs can't get pulled into the fuselage).

I had aleady fitted male JR plugs to four 'overlong' lengths of AirWild heavy duty twisted cable. I now threaded one of these through a the tail exit and fished it forward with a hook I'd made on the end of a long brazing rod. I threaded the servo extension wire through all of the 'keepers' and plugged it into the Emcotec before I cut the extension to the exact length. I cut the other extension wires from this pattern, leaving the two left side extension wires 20mm longer because they had to cross over the fuselage. I fitted sprial wrap at each end, held the JR male plugs together with masking tape and pulled all four wires through a Petflex sleave. I left 10cm free at the front and 15cm free at the aft end before using some heat shrink to seal the ends of the Petflex.

Next job was to solder the Deans plugs to the ends of the 'wiring loom' I'd created and to match the plugs into the stab halves. A quick test to make sure all the servo leads worked properly then the tricky bit...fitting the loom into the fuselage.

I threaded a long length of fishing trace with a small loop in the front through each exit hole and pulled them both forward through the loose cable ties (which I'd previously fitted to the fuselage anchor points). I threaded two Deans plugs through each loop in the wire trace and taped up the plugs and wire loop with masking tape to provide a clean entry, making sure I had the left and right cables sorted properly. I then gently fed the loom through the loose cable ties while gently pulling on the trace wires. A bit of juggling was needed but I managed to get the Deans plug ends through each exit hole without too much trouble. Then it was a simple matter to fit the grommets straigthen it all out and tighten all the cable ties to secure the loom. It looks like a bought one . One final test with aircraft power to make sure all the servos are working and job done.

I had some spare time this afternoon so I fitted the engine cooling baffles. I removed the top half of the cowling and used some old CoreCell to cut a template of the base. When I was happy with this, I cut the baffle from 3mm light ply with the bandsaw and finished it to size with the face sander. I needed to cut the ply in half to fit it under the engine (ply not as flexible as CoreCell). I painted the inside of each half with black heatproof paint before tack fitting the main baffle with super glue.

At this point, I removed the cowling from the aircraft and joined the two sections back together. Working from the back, I used more CoreCell to make templates of the vertical (side) baffles. When I was happy with the shape, I cut these also from 3mm light ply. Before I painted the side baffles, I cut a 3mm rebate along the top and shaped to the angle of the top cowling. When the paint was dry, I superglued a 3mm foam strip into the rebate on the top edge and tack glued in the sides (glue only on the bottom half of the cowling). I finshed up by using a thick epoxy/micro-balloons paste to properly glue all the seams and set it aside to dry.

One less job to do!

looks really good Dad, cant wait to fly it! Hope we get a some cool days over easter to run the engine in..

Byron , how the hell are you ever going to get that plane out of your dads hands .

Ian you have done an axcellent build , if I were you I would find a nice country
strip to fly off and keep the plane all to myself . Its going to be a joy to see this
bird in the air . With the 170 CS up front its going to rip through the sky , hope
to see it soon .

Stu

Ian when I ran in my engine (3W 170 Classic) I used an IR gun to keep a close
eye on the temps . While doing this as an after thought I also tempet the Ign
unit to see if there was any fact to the urban myth about all the heat build up
on the bottom of the unit . The result was myth busted , the ign unit got hot
on its top side and it was not mounted on the engine . The unit was bench
mounted away from radiant (spelling) and in the prop wash .

As a result my ign has been mounted as per instructions and I have had NO
Ign problems , 20 hours of air time and still no issues . The reason I thought
of this is because when I asked "how do you know its getting hot" there was
no clear answear and when pressed I found that no tests had been done .

Just something to think about .

Stu

Byron I would be too scared to fly it....its too nice a job......Im sure it will fly great.....you still going to Cobram? Might see it there...?

Originally Posted by b0Bro'

looks really good Dad, cant wait to fly it! Hope we get a some cool days over easter to run the engine in..