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Martin's Tucano

Retract version

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Martin McIntosh02/12/2012 22:17:31
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3148 forum posts
1133 photos

OK, I got talked into attempting this blog. I am doing a built up wing version with electric retracts.

I realise from the posts on this subject that many of you are trying a scratch build for the first time, let alone one with retractable gear, so I will endeaver to provide as much information as possible including many photos of each stage.

I only started this last week but have a nearly completed wing.

Couple of pics:

tucano 048.jpg

To be continued.

WolstonFlyer02/12/2012 22:32:03
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2104 forum posts
189 photos
It is looking good Martin
Martin McIntosh02/12/2012 22:37:40
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3148 forum posts
1133 photos

Thanks WF, just hope that I can get everything on here OK. Text has already gone a bit haywire.

WolstonFlyer02/12/2012 22:38:59
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2104 forum posts
189 photos
The text looks ok to me.
Martin McIntosh03/12/2012 22:44:55
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3148 forum posts
1133 photos

The wing is built up traditionally with four 1/4x3/16 balsa spars, a 1/8 false LE and a 3/8 sheet true LE, skinned with 1/16 balsa. The section is RAF 30 modified to 15.4% thickness of the chord using Profili s/w. It is in `my photos`but not quite to the correct size which is :root 240mm, tip 140mm. the tip rib is moved forward on the plan by 15mm at the TE. The 11 ribs are spaced at 55mm. Will try to get them on this blog in the right dimensions but there seems to be a problem with the file format.

This is the first wng halfe with the bits fitted.

The first job is to draw the new outline on to the original plan with the spars as shown.

Note that ribs 4&5 hav lightply glued to their outer edges to take theu/c.

After pinning down the front upper spar and adding the ribs (except rib 1), add the upper spar.

Add the rear upper spar.

Cut some very light 1/8 sheet oversize and add the false LE.

Cut four dihedral braces just larger than the spars to the angle shown on the plan and glue the upper ones to the first wing half, up to rib 3.

We can now make and fit the upper skin to this. note from yhe above pic that the 1/16 sheet will be far from straight so carefully cut one edge using a ruler.

Pin to the board using a ruler. Cut one side only of the next sheet then glue together with thin cyano.

Repeat for the next sheet.

Sand both sides with one of these using 80 gri

Martin McIntosh03/12/2012 22:48:32
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3148 forum posts
1133 photos

Continued later. Any problems you see with the above please let me know.

Martin McIntosh04/12/2012 21:05:16
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3148 forum posts
1133 photos

Great! Just spent the last hour or so finishing the wing build blog and it all suddenly disappeared, so will do it again bit by bit.

WolstonFlyer04/12/2012 21:13:58
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2104 forum posts
189 photos
Martin,

The website will log you out after an amount of time.

It is better to post several small updates rather than put everything into one post.
Martin McIntosh04/12/2012 21:38:55
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3148 forum posts
1133 photos

Add rib 1 at half the angle of the braces so that it will be vertical. Cut the skin well oversize, mix Copydex with about 5% water and coat the inside of this and all parts of the top of the wing half. Leave to dry (overnight is OK). Place on the bench and carefully press on and roll over the wing to this Trim off the excess.tucano 031.jpg

Glue the other wing half to this.

tucano 044.jpg

Add the wing TE and aileron LE cut from 3/16 balsa.

tucano 042.jpg

Butt join some 1/16 balsa slightly over length. Wet one side and tape round a suitable tube to suit the wheel diameter. Sellotape around the tube first. This should be of such a size as to leave about 6mm gap around the wheel. When dry, cut the balsa and glue to form a tube. Add a disc of 2mm Depron or 1/16 balsa to the top edge (inside).

Fit the 3/8x14 spruce u/c bearers, and cut through the ribs and spar to suit your u/c leg to take the tube and glue in place. Trim flush. Add the servo rails.

Martin McIntosh04/12/2012 21:58:06
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3148 forum posts
1133 photos

Retrospectively I would make the ailerons from sheet so the built up bits can be removed now.

Add the aileron mounts and cut holes in the ribs for the wiring, adding pull threads to get this in later.

Add the lower braces and skin as for the top. Cut the LE from 3/8 soft balsa, glue on with aliphatic resin and plane/sand when set. Add the aileron and tip blanks made up from sheet balsa and shape the whole lot. Cut the ailerons from the wing and bevel the lower edge to give the required movement.

Remove material to accept the u/c and servos.

Martin McIntosh04/12/2012 22:18:29
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3148 forum posts
1133 photos

We can now fit the wing mounts.

Remove a section of the rear skin and replace with 1/16 ply. Cut a slot for a 3mm lightply plate in the centre of the LE but do not glue until the fus is made.

Fit a piece of light glass cloth or similar top and bottom with acrylic resin or whatever and you are ready to sand and cover. Go over with 320 grit prduction paper (the grey stuff) then with a thin flexible sanding pad (B&Q).

I have not started the rest yet but it should not take too long.

If any of the above is not clear then just ask.

Martin McIntosh16/12/2012 22:32:11
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3148 forum posts
1133 photos

Back to the build which has now come a long way. I shall not bore you with the fus. as it is much the same as any other Tucano except for the bits to follow.

The motor and noseleg mount nearly finished.

The nose from the rear. Sides are 1/8 balsa with 1/8 doublers and 1/4x3/16 longerons.

I did not bother with the triangular bits, just two 3/8 balsa sheets for the top since they are so small.

The cowl is to be from a fibreglass mold. This is the start of the balsa plug.

I used very light 1/4 balsa for the tail feathers which can be seen here trial assembled.

The servos and carbon pushrods trial fitted.

Still lots to do !

Martin McIntosh17/12/2012 22:54:56
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3148 forum posts
1133 photos

The wing fairings are added. Balsa block required at the rear to finish.

The ply is 1/64 and the balsa 1/16. Trim off as required. See general build thread for more details of this.

Martin McIntosh18/12/2012 23:18:42
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3148 forum posts
1133 photos

T

The underbelly fairing is to be added before the wing fillets can be finished.

Mark out the wingbolt centres so that they can be located later.

Using a wing rib template, cut two pieces of balsa for the sides.

Glue these oversize bits to the wing.

Mark out and cut to suit the bottom sheet (I used 1/8).

Add the sheeting and sand to the fus. profile.

End of play for today.

bouncebounce crunch19/12/2012 06:18:30
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1739 forum posts
212 photos

TOP job there Martin,and i must admit your photos and text are better than most instruction books that come with some kits.

What weight range are you aiming for or expecting?

cheers bbc.

Martin McIntosh19/12/2012 19:58:51
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3148 forum posts
1133 photos

Thanks bbc. A lot of this of course does not apply to a model being built from the original design but I hope that there is some information which will assist a newcomer to plan building.

As for weight, the bits so far come to 2lb 9oz inc. 3S 2200 but does not include the Rx, esc, pilots and Oracover so I would not expect less than 3 1/2 lb. Not too worried here as the chosen motor draws 450-475W depending on prop. @ 10400rpm so it should be OK.

MM

Ian Jones19/12/2012 20:11:18
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3219 forum posts
1397 photos

Looks like a dream machine in the making thumbs up

Martin McIntosh25/12/2012 22:35:35
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3148 forum posts
1133 photos

Rather more advanced now. All construction is done, the g/f cowl painted and the covering started.

I am now hoping for an all up weight much closer to 3lbs.

Concave fairings are always very difficult to film cover and this proved to be no exception. Would now recommend 1/64 ply rather than 1/16 balsa.

The tail is covered but not glued in place as yet since the fus. needs to be covered first.

Martin McIntosh25/12/2012 22:43:34
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3148 forum posts
1133 photos

Sorry that you cannot see very much in the last pic. but the black covering must have made everything else white-out on the phone cam.

WolstonFlyer25/12/2012 23:23:16
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2104 forum posts
189 photos
That is looking really good Martin.

I have not started building mine yet, next week I hope.

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