Clean Sweep 60

[Tim Hooper]

So after a couple of hours work cutting out the ribs, the wing has started to become three-dimensional!

I've laid the lower skins root-to-root, then glued the spars in place, followed by the ribs.

At the centre of the the wing I've added an infill piece. This will be cut in two when I set the dihedral angle, and allows a flat hardwood brace to be fitted. You can see the outline of the brace drawn on the plan.

The holes in the skin and ribs are there for the servo leads. But you knew that anyway, didn't you?

Raising the front edge of the lower skin with scraps of balsa brings the skin in contact with the underside of the ribs. I secured the skin here with medium CA for speed.

The upper spar was added and checked for straightness. The very fronts of the ribs were trimmed back as required to get them level with the edge of the lower skin, after which the 1/2 x 3/4 LE was added.

.....and that's quite enough for one evening!

tim

[Concorde Speedbird]

I have never built a built up wing in that way. Mainly because I have only ever built 1 built up wing for my Funfly! It's still in one piece so I must have done something right...

Looking très très nice! (Got triple French tomorrow...)

CS

[Tim Hooper]

CS,

There are many ways to build a wing, and the CS demonstrates just one of them. Drawing the plan on the lower wing skin makes a lot of sense to me.....

Good luck with the Franch lesson!

tim

[Tim Hooper]

Here's a better shot of the wing as it stands.

...and compared to the origisnl 48" version.

The spars have had their infill pieces fitted across the centreline.

I've cut the wing in two, so I re-join it at the desired dihedral angle.

[Tim Hooper]

So after a splendid day at the LMA show at Gaydon today, I've been able to spend an hour or two on the CS. In particular the wing joiner....

The local woodyard sold me a piece of 1/4" luana hardwood (enough for 2 or 3 joiners) for £1.40. The joiner is in the form of a very shallow 'V', so I cut a template from card using the actual wing as a guide, then cut out the luana to match.

After that I marked out the rear of the joiner thus...

I planed away the shaded portions. This is to allow the joiner to sit back against the main spars. It also serves to avoid having a stress-riser by gently tapering the joiner as it blends into the spar.

Here's the finished item installed in the wing, after the root ribs were also added.

Here's the rear view of the centre section.

[Tim Hooper]

So, the next stage is to temporarily add tapered wedges to the underside of the trailing edge, so when the wing is pinned back on the board there's a slight amount of washout induced. The wing is upside-down in this shot, OK?

Here's a tip I picked up from Peter MiIller. With the appropriate panel pinned down to the board (washout included), and the top skin glued/pinned/tasped in place, I piled some old magazines on top to ensure the skin makes full contact with the wing's structure. The magazines spread the load over the maximum area without creating pressure points.

tim

[Tim Hooper]

I've added the second top skin, so whilst that dries I set about assembling the bit for the wing tips.

Pinned and glued together.

Here's the LH tip from above.....

....and below.

[Lee Smalley]

as i said foam wings!!!!!

tim if you can draw up a root and tip profile that would be enough, i could cut my own again i suppose, although the offer of a set in the plan pack would be a big seller i feel

[Tim Hooper]

Posted by Lee Smalley on 01/11/2012 13:27:17:

tim if you can draw up a root and tip profile that would be enough......

OK Lee, I'll print out a set of root and tip profiles and add them to the plan!

Anyway this evening saw the tips rough planed to shape prior to gluing them to the ends of the wings.

Here's the underside showing the concave curve. I used a piece of rough glass paper (wrapped around a piece of tube) to get the initial shape.

I've also cut the ailerons free and bevelled their front edges to allow for top hinging.

At the centre of the trailing edge I've sliced off a portion of the wing and added a bit of infill balsa. This should allow the wing to comfortably fit against a fuselage former.

[Erfolg]

I do like the Hoener tips. In the past I have tended to avoid them. I had an apparently mistaken notion that more block is required than standard type tips. Viewing the tips you have fabricated, it is apparent that the tips can be constructed using less material than the standard type tips. Standard tips do consume quite a lot of material if they are to be reasonably effective in minimising tip losses, having quite a lot of rake back.

Most impressed!

[Tim Hooper]

Erf,

I'm not sure that the Hoehner tips are any more economical than a standard type, but they certainly do look the part!

I've started on the fuselage today, so maybe I'll get some piccies done tomorrow.

tim

[Erfolg]

Tim

I tend to have quite large tips in length, with the objective of getting towards a half ellipse. This approach takes quite a lot of material. Although it should reduce tip losses, it does put some weight where it would be better to have little.

My CS, probably has an extra 6-8" in span over the plan as a consequence.

Your Hoener tips I suspect are at least as effective, ofrvery close. Yet probably are using much less material.

Edited By Erfolg on 04/11/2012 15:34:52

[Tim Hooper]

Erf,

Ah, I see what you mean!

Ok, so at the close of today's business.....

The fuselage sides are cut from 1/8 balsa sheet - scarf jointed near the tail. I've found that if I pin them to the board with the top edges adjacent to each other, then even a numpty like me ends up with an opposing pair, and can't build two sides same!

The doublers are cut from firm 3/16 sheet, and there's triangular stock for the bottom edges.

F1, 3, and 4 are cut from 1/8 plywood. I've added a brace across the nosering to give it a bit of strength whilst get the fuselage into some sort of shape.

With one fuselage side pinned to the board, I've added the main formers, weighting them down as they dry overnight.

Here's the start of the 1/4 framework for the fin. Not only does the fin have to bear the stresses imposed by the T-tail, it also has the elevator snake passing inside it up that diagonal slot. I'll skin both sides with 3/32 sheet.

[Tim Hooper]

Well, after years of building fuselages over nothing more than a drawn centreline, I've eventually invested in a SLEC fuselage jig! So here's the CS60 being assembled inverted in the jig.

I've also added the wing mounts. There'll be additional balsa and ply reinforcement later.

I've turned the fuselage rightsides-up, and joined the front of the sides together with a scrap of balsa to simulate the nosering. This let me take measurements for the 1/4 ply firewall.

You'll notice that the motor mount isn't central on the firewall. Later I'll add washers under the right hand lugs to force the front of the motr shaft towards the centreline, thus adding a couple of degrees of sidethrust.

The idea is that the alloy crosspiece will stay put in its new home, and the motor itself added later through the nosering.

Here's the firewall (F2) being tried for size.

From the rear.

From the front.

[Tim Hooper]

With F2 tacked in place, I shimmed the motor mount on one side to provide the sidethrust, then added the nosering (F1) using the spinner as a guide. There'll be some serious reinforcement later!

Using an awl to pierce through the front wing bolt hole, and into the fuselage mount, I then centred the wing by taking measurements from the TE to the sternpost.

After than the rear bolthole was pierced with another awl, and the position marked on the rear mount plate.

[Robin Kearney]

Looking good Tim.

How did you find using the SLEC jig? I've often been tempted by one, but have yet to take the plunge.

r.

[Tim Hooper]

Robin,

The SLEC is a great idea, but is let down a little in its execution.

You get the 90° brackets, some bolts and blind nuts and a self-adhesive grid, which you're supposed to stick onto a flat board.

The major problem is the grid, in that the lines just aren't straight! Not good for taking useful measurements, eh? The second bugbear is that there just aren't enough blindnuts to fill all the holes.

So in the end I drew my own grid on a piece of board, and bought some additional nuts and bolts.

tim

[Erfolg]

You do not need a SLEC Jig, Oh NO!

What you need is a home made proper jig.

A CS 52 in a HOME MADE JIG.

or in this case a PM Cassuts being set up.

The cost I can here you say? I think about £1.5 for SS cap head screws about £1 for hex head nuts, 50p for washers. The rest found in the garage, felt tips lying about.

[Tim Hooper]

Nice work Erf! Where you lead, the rest of us follow.......

So here's today progress;

With the fin skinned on both sides, I was able to thread the elevator snake through it.

Viewed from above, I've added some additional bracing around the wing mounts, together with 6mm blindnuts.

From below, you can see the blindnut on the forward mount, together with the ply undercarriage plate. I'll sheet over the void later!

The fin is glued between the fuselage sides. I've used a 90° set square to make certain that it's vertical.

The top of the fin will be trimmed later so that the top edge is exactly parallel to the top edge of the fuselage side, thus giving 0° incidence to the tailplane.

Here's a general view of the airframe so far. Looks good to me!

[Tim Hooper]

Now things get a bit fiddly!

I've added the upper sub-formers to the top of the fuselage, preparatory to planking the whole thing as one unit.

With the wing bolted in place, I protected the top of the centre-section with a layer of polythene. The idea is to build the hatch as part of the top decking, then cut it free afterwards. Only then can I remove the wing.

I've added a frame to the top of the wing (cut from 3/32 sheet) to serve as a base for the hatch when it's cut free.

H4 is cut from 2 layers of 1/8 balsa. There's Sellotape in between the layers so that they don't stick together. Once the planking is finished I should be able to run a knife between them to separate the hatch. The same applies at the front of the hatch (F2/H1).

[Stephen Jones]

Hi Tim ,

its coming along nicely now ,

I think that you may struggle a little to sand it just above the wing ,

Just an idea may be worth while building a small section of wing to fit on top of the fuzz so as not to hamper sanding .

could even be out of foam .

[Danny Fenton]

Looks great Tim, much better size

Cheers

Danny

[Tim Hooper]

Thanks guys!

Stephen, I understand what you're saying. On the original CS I removed the hatch and wing after planking, then replaced the hatch and only then finished the sanding.

What I'm really apprehensive about is moulding the canopy......

tim

[Stephen Jones]

Tim , Moulding the canopy is the easy part

Trust me ,

I am sure you have watch videos on it , and you don't need me to tell about it , all you really need to do is make sure that you're plug is reasonably smooth and extends to replace some of the fuzz so that you can cut the mould back to the cockpit line .

Plugs can be made out of wood or foam , plastic or glassed foam which is what i do just depends on how many you intend to make .

[Danny Fenton]

Another trick Tim is to trim the first one you pull and then pull subsequent canopies over the plug AND the first one. Smooths out some of the imperfections, not that your CDO will allow any of course.

You can borrow my vacbox if it will help ?

I have an A4 frame as well as this smaller A5 one that is shown, the hole at the bottom is for my Hoover

Cheers

Danny