Ecureuil / Compass Atom 500 build

[npomeroy]

This is not a full "build" thread, but as I'm near the end I decided to upload some details.
The body was from smartmodel, unpainted, 500 size. There were minor blemishes, and I did enlarge the windshield hole at the top, and re-cast a larger windshield.

I sanded it and primed. The top coat is acrylic lacquer, lightly buffed and coated with a spray-on car polish that has no buffing effect.

This first set of images show window work. I used some soft plastic 1mm tubing from a store that sells craft stuff such as paper flowers, plastic buttons, etc. slit lengthwise to form the rims for the windows. I ran a bead of medium CA around the inside (mostly on the fibreglass - just touching the black tube) to hold it. the formed windows that came with the fuse were stuck in over the black tube with heavy duty double sided tape (sold to hold carpets down). I cut the edges in lots of places to flatten the cast-in curve.
The windows were all airbushed on the inside with clear acrylic blended to make a dull dark tint. the main windshield was also stuck on with the same double sided tape and covered over with black vinyl electrical tape. You can see that the tape is contracting a bit at the edges.

More posts to follow.

Nelson NZ

[npomeroy]

More fuse mods:
The Jet exhaust supplied with fuse kits usually looks thick walled and strange colour. So I rolled one from this clear polyester sheet, and inserted it in a foam bulkhead. The horizontal stabs I cut large gaps in the inner edge, stuffed balsa and expanding foam inside, which I thin used to anchor CF rod. The rods and holes match up (to be glued finally) as per the images. The kit fuse was flat on front, i.e. no air intake, so I cut one and used polyester filler (the one that uses red accelerator) to form the edges of the hole (see the previous post to see this from the outside).
The supplied skids are simply rounded at the front. I glued wooden dowel inside the aluminium tube, cut and ground it to the right bevel, epoxied on a platform of ply, faired it in with filler, and finished it with wet-n-dry 360 grit for the non slip surface.

[aliboy]

Hi,

Nice build. I'm interested to know how you recast the main window. I'm building a BO-105 at the moment and have damaged one of the windows. Would be good to make another.

Thanks, Al.

[npomeroy]

Mechanics:
It seems most fuse kits are designed around Align mechanics that attach the skids with vertical screws. The Atom skids have horizontal screws. So I made aluminium brackets for bolting the mechanics to the plywood deck.

I use the Skookum SK720 FBL unit. I made a plywood mount up front so it would be accessible in the scale fuse.

C/g requires front weight so the Lipo holder has ben extended forward. Angle aluminium extends the CF frame, and the deck is 1/8" balsa sanwiched between 1/32" ply.

I seem to have a problem with this post - if no images appear, I'll post again.

[npomeroy]

Here are the missing images

[npomeroy]

Originally Posted by aliboy

Hi,

Nice build. I'm interested to know how you recast the main window. I'm building a BO-105 at the moment and have damaged one of the windows. Would be good to make another.

Thanks, Al.

Hi Al. The idea is to make a male form with the correct curvature. I used the supplied window, supported in a small box of plaster of paris. The plug I formed with plaster of paris (poured into the old screen) , with about 20% cement powder (yes, like you make concrete with) which makes it set faster and harder. Then the male plug I sanded and filled as needed.
Then you get some clear sheet (1 mm PETG I used), staple and tape it to a plywood frame just bigger than the male plug, soften it over a glowing heater or stove element, and press it down over the plug. This needs some practice so get spare sheet. Also, my plaster-based plug was impossible to get 100% grit free - which showed as dimples on the plastic. So I repeatedly painted/sanded/filled/sanded it using acrylic lacqer primer paint. This eventually gave a good surface. You could also use polyester filler putty for the plug.

hope this helps - not much time now to write more but am happy to follow you through on this - I've done a lot of this sort of forming in my time.

Nelson NZ

[aliboy]

Thanks for the explanation, sounds like fun!

Al.

[npomeroy]

And here is another thread in which I've described the fan ventilation system.
https://www.helifreak.com/showthread.php?t=385000

[npomeroy]

Here is an image of the front small window with LED landing lights inside - one pointing forward, one downwards.

Also the finished model - another image is in the "show of your scale bodies" sticky.

Test flight today - went fine. The motor just got moderately warm after 5 minutes.

Nelson NZ