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rotax618

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I cut out an instrument panel which was too long for the Y axis of my CNC, I was able to do it using Estlcam, it lets you place the origin anywhere and create a path for as much as your CNC can handle, then move the workpiece and cut the other half.
 

Rhino

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Oops. Wrong thread.
 
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rtfm

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I cut out an instrument panel which was too long for the Y axis of my CNC, I was able to do it using Estlcam, it lets you place the origin anywhere and create a path for as much as your CNC can handle, then move the workpiece and cut the other half.
Not a bad idea. I hadn't thought of that, to be honest.
 

rtfm

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OK, here goes build #2. I'm not counting the time taken to cut the pieces (1 day, BTW) because that's not *building*.
Day 1:
Bonded the RHS of the fuse. This involved fitting the front and aft skins together using the jig-saw joint. If you look carefully you can just see the joint about mid-way along. Also in the picture is the seat doubler.
1623284462323.png
I then rolled on a thin coat of West System epoxy to seal the inside (I forgot to do this first time round).

Next, I fitted the two halves of the airframe together, and thoroughly coated the inside surface with West System. While nice and juicy, I lay the airframe on the skin. A satisfying bit of epoxy ooze all round. This time, I cut the skins oversize by exactly the thickness of the firewall (9mm), outer bulkheads (3mm), panels, seat (9mm) etc. This way, these panels will fit nicely between the skin extensions, leaving very little to chance as far as alignment is concerned.
1623285496690.png

Finally, I coated the inside of the seat doubler and placed it carefully. Then clamps and bricks (my go-to (cheap) weights.
1623285645220.png

The result was marvelous. Here is the finished side lying on my router table (the build table is too cluttered with parts to accommodate this finished side)
1623285753126.png

Build time: 3 hours

Regards
Duncan
 

Bill-Higdon

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Salem, Oregon, USA
OK, here goes build #2. I'm not counting the time taken to cut the pieces (1 day, BTW) because that's not *building*.
Day 1:
Bonded the RHS of the fuse. This involved fitting the front and aft skins together using the jig-saw joint. If you look carefully you can just see the joint about mid-way along. Also in the picture is the seat doubler.
View attachment 111558
I then rolled on a thin coat of West System epoxy to seal the inside (I forgot to do this first time round).

Next, I fitted the two halves of the airframe together, and thoroughly coated the inside surface with West System. While nice and juicy, I lay the airframe on the skin. A satisfying bit of epoxy ooze all round. This time, I cut the skins oversize by exactly the thickness of the firewall (9mm), outer bulkheads (3mm), panels, seat (9mm) etc. This way, these panels will fit nicely between the skin extensions, leaving very little to chance as far as alignment is concerned.
View attachment 111559

Finally, I coated the inside of the seat doubler and placed it carefully. Then clamps and bricks (my go-to (cheap) weights.
View attachment 111562

The result was marvelous. Here is the finished side lying on my router table (the build table is too cluttered with parts to accommodate this finished side)
View attachment 111563

Build time: 3 hours

Regards
Duncan
Robert Haines Built his CNC Router table so it could function as both CNC Router & work Bench, This is the CNC that cut the Tubes for the EAA 292 Facetmobile & is cutting the tubes for another project the designer of is also a member of this Demented group of Avi8on Enthusiasts.:eek:
 

rtfm

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Day 2:
Built the left side of the fuse. First step - lay the two skins on the build table, fitting the jig-saw joins. Having a good cnc router is a great thing.
1623312394707.png

Step 2... trial fit the ply airframe, checking that the skins overlap on all sides. Then fit the under seat brace.
1623312617693.png

Then roll on a thin layer of West System epoxy. Seals the inside, and prepares for the bonding of the airframe.
1623312776154.png

Finally juice up the two halves of the airframe really well, and squish them onto the skin. We're looking for a bit of squish when we apply a bit of pressure. Pressure applied with magic bricks. And a few handy tools. Two dozen more bricks on the way...
1623312920943.png

Building time: 2.5 hours
 

rtfm

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Day 3:
Today I sealed the rest of the insides of the fuse sides. Back-breaking work. I rolled epoxy on the actual airframe, but the important surfaces are, of course, the end-grain sides. These had to be coated with a brush. Every hole. Took forever. Well, about 1.5hrs to be exact. Now I have to wait till this lot cures. I also sealed the end-grain of the fin and rudder. Now I'm bushed.

In retrospect, it would have been a LOT easier and quicker to seal the end-grain sides of all the holes BEFORE I bonded the airframes to the skins. This is what I did with the fin and rudder. Held them up, and ran the roller round each hole. Took about 5 minutes.

Added that to the build manual.

I can see why some guys want to leave their wooden planes "naked" as it were. The wood is gorgeous.

1623372936704.png
Those of you with eagle-eyes will notice some end-surfaces which have NOT been sealed. That's because the bulkheads have to be bonded to these surfaces, and epoxy sticks better to wood than it does to epoxy.

It's been uncharacteristically cold here of late, and the epoxy is taking it's own good time to cure properly. So I'll have to leave things as they are for another 24hrs.

Building time: 1.5hrs

The rest of the day will be spent at the laptop finalising the wing design. I've gone with a sexy looking wing rather than a rectangular one. Four panels, dihedral of 0 deg, 1 deg, 6 deg and 15 deg. Like this:

1623373252760.png

The trailing edge is straight, not curved as the above pic shows.

1623373276861.png

All ribs 7mm ply to reduce the issues identified earlier with the 30mm wide foam ribs.

The internal structure is very simple, although it appears cluttered.

1623373315124.png

The red mini spars are the anchors for the upward folding outer wing. I'll add some meat either side to provide a base for the hinges to attach to. The front section of this mini spar is also the wing pivot attachment. The two yellow mini spars do similar service for the outer panel which folds downward. This arrangement allows the fully folded wing to be extremely narrow (2m).

Finally, I've decided not to go with D-tubes, but to use a single sheet to cover the entire top of the wing (and bottom, of course). This requires a solid spruce leading edge (50mm deep), cut as follows:

1623373371193.png

And that's how far I've got with the design.

Oh, I'm using a "X" design for the rib bracing, like this:

1623373396753.png

Of course, every rib is a different size, but on a cnc router, that is immaterial. The 16mm diam circle at the rear is for the drag/anti-drag bar.

The full rear wing will weigh about 18kg, and have an area of 3.9 m^2

Regards,
Duncan
 

rtfm

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Not crooked at all. Each panel is a separate entity, and each panel has a spar running along the 40% chord line. Otherwise, what would you suggest?
 

rtfm

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Explain? Do you mean length of span?

Anyone else care to chip in re: my current spar arrangement vs a straight spar?
 

rtfm

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Mmmm Isn't that true for all wings of this plan view? Panels C and D contribute relatively little to the overall lift. Panel D is almost a winglet.
 

rotax618

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Evans Head Australia
If you want the lightest structure you should simplify the load paths, what advantage is that planform?, make sure the advantages outweigh the disadvantages, for a very light slow aircraft it is difficult to argue against a simple rectangular planform, a slightly more complex shape would be the Jodel wing with rectangular centre and tapered tips - note the Jodel has a straight spar in plan view.
 
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