WolstonFlyer's Tucano

[Martin McIntosh]

Hi WF, I hope that you have planed and sanded those nice wing halves before you think about joining them? I may have missed a bit of your build.

[fly boy3]

Normally the harder the balsa the heavier it is. Good idea to way it though. Cheers

[Martin McIntosh]

Whilst it is a good idea to get each wing half the same weight/density the model is best balanced on a test flight. Simply fly exactly downwind at height, close the throttle and push into a half outside loop, ensuring that the wings are level. Observe which wing is low at the bottom and add a little weight to the opposite tip. You will only require a small nail with the head cut off and pushed into the tip.

WF. I would use epoxy to join a wing as thin as this. Aliphatic will shrink so much that there will be very little glue left in a butt joint such as this.

[WolstonFlyer]

Hi Martin

There is not a lot of spare width in the sheets to plane and sand the long edges. The centre sections need to be exactly 100mm so are just a length of the sheet but I did check it and cut from areas with nice straight square edges.

The LE and TE are just a little bit over size, I will run down the edges with a sanding block just before I set it all up for gluing tonight.

A Permagrit block is a tool that I think would be handy to have. I will make do with a length of 2"x4" with sand paper stuck to one face.

[WolstonFlyer]

There is a lot of shaping to do on the wings with a razor plane to get the profile, would epoxy make that job very hard to do?

I am going to use epoxy to join the 2 wing halves together and to fix in the ply dihedral braces.

Edited By WolstonFlyer on 06/01/2013 19:45:48

Edited By WolstonFlyer on 06/01/2013 19:46:57

[Martin McIntosh]

WF, what I meant was, I hope that they are shaped to the wing section before you join them because you would find this very difficult afterwards. Best to lay them both flat on the board, spot glued together and shaped as one piece, including the ailerons. Mark the centre all round with a pen between your finger and thumb first. You can then cut at the centre, cut out the ailerons then bevel the centre and join.

[WolstonFlyer]

Hi Martin

I just read your post again and I am not quite at the stage of joining the wings together yet.

I will be planing and sanding the joints between the two wing halves, I have yet to cut the wings to final length and make the flat centre section with ply dihedral braces. My wing will be in 3 sections as per Phil's design with a flat centre section.

[WolstonFlyer]

Ahh ok so it is a good idea to do a temp join between the two wings and then plane and sand the profile so they are all equal. Then split the two halves and then cut out the ailerons then join it all back together for the final time with epoxy and the ply braces?

[Martin McIntosh]

That`s it! Make the tail in a similar fashion and cut the elevators out afterwards. I do not see the need to make the wing centre section flat-my built up one does not have this. Use a 1" wide lightply plate for the tongue at the front because it is much easier to align with a slot in the former than dowels.

[woody]

I always shape my wings after gluing all the parts together I've built a few of tony nijhuis designs and this is how he says to do it.

But I do see what Martin is saying and it doesn't sound a bad idea. 

The glue I use to join wing parts is titebond wood glue. 

Cheers woody

 

Edited By woody on 06/01/2013 20:34:04

[WolstonFlyer]

Hi Martin

I am trying to follow Phil's design for a removable wing. He has added a flat middle section with 2 dihedral breaks in line with each fuse side, rather than a single join down the middle of the wing.

I am just a bit worried about deviating from the design that Phil has drawn up on CAD because I have never done this before.

I think I can picture how a different design of removable wing might work, similar to how Phil has done it with a ply tongue to go into former F3 then wing bolts at the front. But rather than adding the whole centre section for a flat area just create a small flat area in the V of the dihedral to fix the ply tongue to and build up some thickness at the front for the wing bolts.

I will have to think about which route to take. I cannot really afford to make a mess of this and buy more balsa at the moment.

[WolstonFlyer]

Hi Woody, it does look like a good idea to temporarily join the two wing halves together to do the shaping of the profile then cut out the ailerons after. I am sold on the idea.

[Martin McIntosh]

Think about this before you go any further. A wing join in the centre will suffer very little strain. One on the fuselage line will have to take an enormous load when up elevator is applied. Try holding a piece of balsa over the edge of your bench then applying downward pressure. Where does it break? Not where your holding hand is.

I have not looked at Phil`s drawing but why put a tongue at the rear and the bolts at the front? I know it has a rectangular section but look at almost any other model plan and you will see that it is the other way round for a very good reason.

The aileron servo. Since the wing is now to be removable there is no reason why this should not be let in to the wing and simply coupled to the torque rods.

[WolstonFlyer]

Yes I see your point Martin, the original design uses the slight triangle between the central wing joint and the sides of the fuselage to create strength. The three section wing will put more load on the two ply braces and the glue joint.

I think I did ask this question about the three section wing on the general thread (or perhaps on Phil's thread) and Tim @ modelmarkings.com replied saying that his 1st Tucano (built a few years ago and still flying) used the three section wing and it has been strong enough.

Here is a picture from Tim

So now I am not quite sure what design to go with. I need a removable wing because of storage space and my landings are likely to be on the heavy(er) side ( I am quite new to flying and still have to pass my A test yet).

Anyway, I have glued up all of the individual pieces that form the wing panels. Packing tape on the underside of the joints to help hold them together and stop the glue sticking the wings to the table. Both panels are weighted down while they dry overnight.

I will have a think about the design "problem" tomorrow... while I am at work LOL.

[Tim C]

Hmm a bit of a debate going on here, here is my 10c worth.

1. I would make up the wing halfs flat before any shaping

2 As for glue, I have used Cyano, PVA and aliphatic, i would avoid PU or epoxy, for preference I wouild use PVA or aliphatic here

3. I use a couple of mini sash cramps to hold the wing panels together while the glue sets

4. If you opt for the 3 part wing. I would extend the the ply joiners. this is the stress point and it gives a bigger glue surface to the wing panels and I would use epoxy as glue of choice for the centre panel joins

5. my 3 part wing has help up so far, but then I am a gentle not aerobatic flyer, its no my idea , but one from Nigel Hawes who used it I belive on one of his Hawk designs

6. There is no reason why a 2 part wing could not be made removable, you would need more work/fitting to get it mounted/lined up, but 2 screws fwd and ply toung to rear would probably be ok

7. For the removabl;e wing option I would certainly go for a fwd servo option with servo in the wing (similar to nigels Fizza Wing) which incidently I made removable on mine, two screws and a ply tongue. More than strong enough when I totalled the plane big cartwheel after hitting a tree, wing is intact, but fuse wrecked where battery ejected still attached to velcro and large lump of balsa!!

[WolstonFlyer]

It has been quite some time since I glued up the wing panels, family life and work keep getting in the way.

Well here is a tip for people shaping their wings.

Don't do it in the kitchen when your wife is at home

I had just created a 'massive' pile of curly balsa shavings and dust a result of shaping the trailing edge of one wing.

I was having great fun with the razor plane and sand paper until my better half entered the room and in the process 'swooshing' the door open.... said shavings and dust are now in every far corner of the room and the worktops look like it has been snowing balsa dust for half an hour.

....... so that's me in trouble LOL, now where is the vacuum cleaner.

[Colin Leighfield]

I don't see any problem with the three part wing. As long as the mating surfaces are reasonably true and gaps completely filled with epoxy, it isn't going to break at the wing roots. There shouldn't be any particular need to lengthen the ply braces by much either, if there's that much load being transmitted through them the gluing along the mating faces couldn't haven't been very good in the first place. Epoxy doesn't bend that much and I certainly wouldn't use PVA for that job, although it's fine for the dihedral braces.

I've already got thoughts on my next o/d build based on Nigel's ideas as soon as I finish the Toucano and that will definitely have the three piece wing. It won't be detachable though, at this size I don't need it to be.

[Tim C]

LOL, I keep a brush and pan handy as well as one of those battery powered mini hoovers, sweep up the shavings as you go, and hoover up the dust before it leaves a snow cloud.

[WolstonFlyer]

I think I am going for the three part wing but I have made the slots for the ply braces quite a bit longer. They will extend about 100mm into each wing so should give plenty of strength and also help prevent twisting.

I am not sure if I should use the 5mm leading edge stock I have bought, will it add any strength to the wing compared to the shaped balsa panel?

For the next wing I will vacuum the dust and shavings as I go, oh well the kitchen needed a wipe down anyway

[WolstonFlyer]

Here are a few update pictures for people following along with this "newbie" builder (me)

One shaped wing

I don't think I have quite got the profile right at the very tip, I have made it a bit too flat I think (got carried away sanding out a scratch) but hey I am new to this. I will just have to make sure the other side is the same!

Quick question: Apart from being very careful, how do I stop the wood picking up little "dings" and scratches as I build... this stuff is much softer than I thought it would be!

Edited By WolstonFlyer on 13/02/2013 15:35:48

[fly boy3]

Hi WF, years ago there was kit on the market called the Splatfire. Ha ha, All instructions said was sand wings to a profile. The dozen or so at our club therefore had all different profiles, but all flew well. As you say as long as both wings are the same,you will be fine. Cheers.

[Codename-John]

If you put a little bit of spit on any dings and scratches, then leave it 5 mins, they magically dissapear

[WolstonFlyer]

Hi fly boy3 - Like you say I think it will be OK, I have had another look at the profile and it seems to just be the very tip that got the "too much" sanding treatment. I must get some finer papers, I have been using some M3 P-180 grit that I found in the back of the shed.

Great tip Codename-John, I guess the bit of moisture expands the wood back to where it started - I would never have thought of that

[WolstonFlyer]

After a rather long buiding gap I actually have a whole day off work today so will have a good 7 or 8 hours of building I also have next monday off work as well - this is unheard of! (actually I have a few days of holiday I have to use by the end of March or I lose them)

So I have just completed shaping my wings and have cut out the hard point on the first wing for the undercarriage mounting. I have used the top tip from Tim @ modelmarkings and have made a special tool from 3mm ply and it works much better than I thought it would, thanks Tim

Just starting on the other wing and will then epoxy them all in.

Edited By WolstonFlyer on 04/03/2013 10:25:29

[WolstonFlyer]

Next job was to cut out the fuselage sides, they do not quite fit on 4" wide sheet, a little triangle has to be stuck on to make up the point at the top of where F3 goes.

The formers are next.