Another Ozzie Extreme Composites 40% Extra 260 Build

[excelpoint]

very nice mate.

[b0Bro's dad]

Thanks Guys, I appreciate all your support. Now I have to make it fly.....

[The Hobbyman]

Looks great Ian.

[b0Bro's dad]

Now that I have the beast back, I can do some work on it. First up was to build and fit the undercarriage strengthening plate from 2mm carbon sheet.
It was easy enough to measure the width of the 'channel' between the two frames and cut a strip of carbon slightly oversize using my sewing machine 'jig saw' and a blade made from an old hack saw. I used the face sander and lots of trial fits to trim the plate to an exact size that just sitted between the two fuselage frames. This step required patience as the fuselage slopes front to rear and top to bottom as well as needing to radius the corners to fit over the glue fillets between the frames and the fuselage. It was important to have the undecarriage legs in place during this step to get the size just right.
The next bit, locating the bolt holes, was a pain because Xtreme hadn't fitted the blind nuts 'square' to the lateral centreline or vertical. I used a bit of double sided tape to hold the legs in their correct position (determined by temp fitting the bolts). while I used a paper template to mark as accurately as I could where the bolts exited the top of the undercarriage legs. I then taped the paper template to the carbon plate, held my breath, and used my drill press to drill four slightly undersize holes through the template and carbon plate. I could now temp fit the bolts in the undercarriage legs and use a torch to visually locate the bolt centres. To my relief, most were 'in the ball park' but two needed a bit of work with the round file to get the bolts to 'start' properly.
Then, I removed the double sided tape from the channel and smeared the undercarriage legs with car polish to prevent the epoxy sticking to them and assembled the whole shebang with the bolts finger tight to hold it all together for gluing. I used 1.5 oz fibreglass cloth and epoxy to reinforce the plate against the frames and up the sides of the fuselage as well as gluing the edges of the plate to the frames. I reinforced the centre with more glass cloth and epoxy.
It was then left overnight to cure and before I removed the bolts next morning. A bit of the epoxy had seeped through and I need to 'work' the legs a little fore and aft to free them. A quick clean up of the legs and the plate with some fine sandpaper and the reinforcing plate was done.

[b0Bro's dad]

After going through three different brands of 'large' wheel axles, I eventually decided to use a pair of 6mm x 65mm stainless steel bolts as the easiest, neatest and most secure method of fitting the 125 mm dubro 'lite' wheels to the undercarriage legs inside the spats.
The spats needed just a little 'clean out' of the moulded socket to properly fit the undercarriage legs. At this point, I sorted out which leg was which and clearly marked the undercarriage legs 'left' and right'. I marked both legs 15mm from the end and 15mm from each side for the 6mm axle bolt. Using a table vice to hold each leg square, I drilled the 6 mm axle holes through the undercarriage legs. Dry fitting the spats onto onto the legs, I used this hole to scribe the centres onto the inside face of each spat (remember left and right) and drilled each spat with a 6mm hole on the inside face only.
I then marked each leg for the 3mm retaining bolt and repeated the whole process while using the 6mm bolt inserted through the undercarriage leg and spat to ensure proper alignment. I then attached each spat with the 3mm bolt, steel washers and a nylock nut done up nice and tight (you can't get to this nut again without dis-assembling the wheel).
The wheel axle needed to be threaded in the right order; I used a steel washer between the bolt head and the undercarriage leg, another steel washer inside the spat, 2 x stainless steel nuts, 2 x nylon washers (spacing), the wheel, another nylon washer and finally a stainless steel nylock retaining nut. It was a bit fiddly assembling all this inside the spat but there was just enough room to use an 11 mm crescent spanner between the wheel and the inside face and another 11 mm crescent spanner between the wheel and the outside face. The method was to tighten the first nut hard to hold the axle, then use the second nut tightened against the first as a 'lock nut', then to tighten the outside nylock nut just enough to let each wheel turn freely.
Fitting the tail wheel was simplicity itself as Xtreme Composites had already fitted a reinforcing plate in the tail. All I had to do was locate the plate with a torch and drill a hole on the aircraft centreline for the 'peg' in the RC Blimp 'large' titanium tail wheel. Then it was just a matter of making sure it all lined up while I drilled and screwed the four retaining clamps.
I couldn't resist fitting the main undercarriage legs and puting it on it's wheels for the first time. Looks sweet

[b0Bro']

Yummy, she is on her wheels!! And have to say, looks like a very neat re-inforceing job. Glad you had the patience for it..

[b0Bro's dad]

The next big step was to mount the engine. I started by marking the cone for the 10 x 4mm bolts spaced evenly around the circumference while making sure that I didn't conflict with any frames in the fuselage. I drilled the holes through the cone then taped the cone into position on the firewall. After making sure the cone was properly aligned (I used a long straight edge and sighted across the top to get rid of any twist), I used the cone as a template to drill the firewall for one of the top bolts. After inserting this bolt through the cone and firewall to hold the alignment, I repeated the exercise for one of the bottom bolts. With two bolts in place, I drilled the rest of the holes and fitted the remaining bolts. I removed the cone and used the bolts directly through the firewall to locate the blind nuts which were secured inside of the firewall with a stiff epoxy and micro balloons mix.
Aligning the engine on the engine plate was a bit tricky. Fortunately, I have a stairwell that allowed me to 'hang' the model vertically and work safely at the top which made this step much easier. After padding the stair rails and hanging the model, making very sure that it was secure, I sat the engine on the plate and mounted the cowling. I could then fit the spinner base and carefully move the engine on the plate to get the spinner aligned. This procedure showed that I needed a cutout in the underside of the cowling for the carbureter intake. I marked where this needed to go and disassembled the cowling etc. After lining up the centre and measuring the intake, I marked the outline of the cutout and used a drill and dremal tool to make the incision and tidied it up with flat and round files.
Back to the model and this time I could move the engine into exactly the right spot. After tripple checking the alignment, I very carefully removed the cowling and used a scribe through the engine lug to mark the position of the top right engine bolt onto the engine plate. Then it was time to disassemble the cone and remove the engine plate for drilling the first hole on the drill press. After inserting this first bolt, I measured, marked and drilled the rest of the holes making sure that everything was square to the top face of the engine plate.
Now it was time to remove the engine and mount the plate back on the cone, using a scribe through the engine bolt holes to mark the cone for the 'relief' holes for the heads of the engine bolts. These were drilled undersize (I didn't have a drill bit large enough) and finished to 13mm diameter with the dremal. After that, it reassemble the engine plate, mount the engine, mount the cone and refit the cowling. To my immense relief it all lined up nicely when I put the spinner back on.
If all that sounds confusing, you should get the idea of the process from the attached pics.

[b0Bro']

Good to see her taking shape dad. Cant wait to come home to it. Just need the inards to go in now

[b0Bro's dad]

I had been puting off this job, first because I had to head down to Canberra last weekend, and second because cutting the cone looked like it was going to be a bastard to line up properly. I started by trolling through Tony's photos to see how he had done his but was disappointed to find I didn't have any clear shots of the cutout and that Tony appeared to have used the 3W 'deep' headers and tuned pipes. I had the 3W 'short' headers and 70mm cannisters.
I started by mounting the engine with the headers onto the cone and sighted along the header to mark the cone for the centre of each cannister. I was a bit perplexed when this method showed that I would need to cut into part of the strengthening 'webs' in the cone but I couldn't see another way around it. In retrospect, it would have been easier at this stage to simply ring Ernie at 3W and swap the 'short' headers for the 'deep' version but I was wary of going too deep as Tony's photos showed his tuned pipes slightly inset into the undercarriage girder frame, and I had built this area up with the reinforcing plate. Eventually, I decided that the cannister cut-outs wouldn't weaken the structure too much and it would be a simple matter to epoxy a 6mm carbon rod inside each 'web' as additional reinforcing.
I started out trying to minimise the hole by using a 25mm hole saw and the Dremal sanding drum from there but quickly discovered this chewed up sanding drums, took forever and covered everything in sanding dust. Now, with two 80mm holes in the cone backplate, I was able to trial fit the cannisters and discovered more drastic surgery was required. I used the (misaligned) cannisters to mark the required cut-outs on the sides and bottom the web and used the hole saw to drill overlapping holes inside the marks. With the big peices now gone, I could use the Dremal tool to tidy it up for another trial fit. A bit more work was required to sit the cannister nicely and accommodate the smoke nipple from the right cannister. Then it was a sandpaper block the square it all up and do a full trial mount on the fuselage. This worked out pretty well except, as I discovered when I mounted the cowling, the exhausts were now about 20mm too short to exit through the cowling.
It now looked like I needed the 3W 'deep' headers after all but that would also mean a new cone as well (not very happy at this point). Thinking it through, I decided to ring Ernie at 3W to see if I could extend the exhausts. He couldn't have been more helpful and offered to check with 3W to see if we could weld longer exhausts into the existing cannisters without putting too much back pressure on the engine. I thought that I would share the pics of progress to date while I wait for that advice.

[b0Bro's dad]

Byron,

I'm glad to see you're awake. Great weekend and beat Hayden 2 out of three times on the golf course. Moet looking good too.

Dad

[b0Bro']

Hey dad, sorry i missed your post. I dont know how you managed to beat hayden, must have been a fluke. However glad to hear that moet is okay. Miss that dog to bits.

Anyways, we are having some going away drinks tonight, only this time its better because im leaving to go home!!! Talk soon.

[3dubya]

Very good job, gives me an idea on my 2nd 3.1 how to mount cans. I got pipes in mine and I hate them, they make a great motor throttle weird. Ill probably follow the same lines as what you have done with the low drop 3w headers, but the motor does need to be 30mm or so further forward for cg (the way i like it). I'm thinking of putting most of the standoffs on the dome mount, if you moved the motor 30mm forward the cans would take out that webbing on bottom of dome and things could be dangerous. Good job very impressive.