Savannah S Build Notes - Wing Nose Skin and Closure

[IBob]

The nose skin is largely as outline by Kyle Communications, with one minor difference.

 

This is a simple, easy, and thoroughly enjoyable step.

 

Thank you Mark for showing the way.

 

My kit manufactured December 2014.

 

Comments and suggestions welcomed. Always.

 

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Some Prep notes first:

 

Each front rib nose appears through the nose skin as a faintly visible raised line.

 

On my first wing, despite what I thought was careful deburring and prep, this line is not smoothe. I have seen this on at least one other Savannah.

 

For my second wing I took particular care to file round the nose of the rib until all manufacturing irregularities were removed. I then 'rolled' this edge with more filing round the nose, to present a soft edge to the nose skin, finishing with emery and scotchbrite. I removed as little material as possible, to maintain a good fit. Time approx 1hr.

 

The manual suggests squaring the edges of all ribs. I did try this initially on a nose rib, but the rib went quickly from flat to curved (as you would expect). This can then be corrected by skillful re-crimping of the edges, but I chose to leave the nose ribs alone.

 

I did square the edges on the main ribs, which do not deform in the same way. I planed an angle on the edge of a wood block until it gave the necessary amount of 'over bend' to result in a 90 degree edge. This made it quick and easy.

 

 

 

 

 

[IBob]

The internals of the wing are all fully assembled.

 

Check all fitting and fastening, including the 2 bolts for the rear strut attachment plate.

 

Cleko in place top and bottom skins, and bottom rear skins. The more the clekoes the better, I clekoed every other hole.

 

Check that these skins are all sitting well and free of waves or wrinkles at this point: if not, stop and sort this out now.

 

Fit wiring for wingtip strobe etc.

 

 

 

[IBob]

The manual suggests fitting the nose skin from the underside of the wing first. I have tried it both ways, and I think this is the easier way:

 

Cleko nose skin to underside of main spar, and to underside of nose ribs.

 

Turn wing over, being careful with free edge of nose skin.

 

Fit temporary wood 'fence' along edge of bench. The wing trailing edge will press against this, while the closing strops will pass around it.

 

I used 75x35 fingerjointed ceiling batten. It's not the cheapest, but it's clean and straight.

 

 

 

 

[IBob]

The wing is supported on wooden fillets, to hold the clekos clear of the bench.

 

I used 4x2, ripped to 2x2, then wrapped in bubble wrap. They are positioned under or immediately next to wing rib, and I check the position often while working on the wing.

 

Use the straps supplied with the kit, round the wing, to begin supporting and curving the nose skin. Handle the skin very carefully and evenly at this point, it is very easy to dent if the bend sags in some way along the length.

 

Insert 2 pieces of wood the length of the wing. I used the 75x35 fingerjointed batten here too. Initially, they rest on the wing support fillets, which are pulled out a little. Again, be careful of the nose skin when positioning these.

 

 

 

 

[IBob]

Now take up evenly and by degrees on the straps to bring the nose skin round.

 

As you do this, flatten the 2 pieces of wood to the nose skin, so that they are pressing round the tightest part of the curve.

 

At this point, the skin is most of the way to the top of the main spar, but still very loose round the nose rib.

 

 

 

[Kyle Communications]

Glad you found it helpful..the first wing I did was a bit harder as I only used 1 length then I used the 2 lengths of wood and it was so much better and easier . Very simple to do by yourself

 

 

[IBob]

Next, set up the strops. These pass under the wing, round the wooden 'fence' at the trailing edge, and back over the top, so that when they are tightened they will pull the wing back into the fence.

 

I used 4 strops which worked okay, one or two more would probably be better.

 

I ran the strops at or immediately next to rib positions.

 

Particular care must be taken not to foul the clekos, both under and over the wing.

 

Ice cream lids or similar go under the strop hardware to protect the skins.

 

 

 

[IBob]

Now take up gradually and evenly on the strops, lifting the skin edge onto the top skin as they meet.

 

Continue to check the strops are clear of clekos etc.

 

 

 

 

 

 

[IBob]

My centre strops were quite tight by the time the skin was in place. I was careful to keep them positioned over ribs.

 

The clekos then went in from the wingtip, where the holes were easily aligned, working easily to the wing root, bumping gently on the wood at the leading edge to nudge the holes where necessary.

 

Then off with the strops and straps, and take the time to admire what you have done!

 

 

 

 

 

 

[IBob]

Glad you found it helpful..the first wing I did was a bit harder as I only used 1 length then I used the 2 lengths of wood and it was so much better and easier . Very simple to do by yourself

Thanks, Mark.

I've done it alone from top down (don't ask) and I'd really not recommend that.

 

Bottom up i've done it with 1 piece of wood then 2, both times no probs, though I think 1 bit carries far too much risk of denting the skin.

 

As you say, it's easily done on your own.

 

 

[IBob]

Closing up:

 

The manual gives the riveting sequence for this. It also identifies several areas on the lower wing which should not be riveted, allowing other parts to be fitted later.

 

One of these areas is the mainspar and rib adjacent to the main strut stub.

 

On my first wing I had problems with the lower skin in this area. On the second wing, rather than skipping the 'do not rivet' bits in this area, I decided to do the fitting as I went, allowing me a clean continuous run of rivets out to the wingtip.

 

It's simple and there's not much to it, here is how it goes:

 

Starting at the point identified in the manual, rivet towards the wingtip, but stop level with the bolt hole in the main strut stub.

 

 

 

[IBob]

Next, check the fit of the long rib stiffener that tucks under the strut stub. It's a neat fit, but should go. Cleko in place.

 

Now offer up the triangular plate. It will need a hole drilled to clear the rivet in the strut stub: I held it in place and rubbed it to get the drilling position. It's the top right 8mm hole in the pic.

 

 

 

[IBob]

Check that all fits okay under the strut stub.

 

Now take the 2 pieces out and rivet them together, but only the 3 holes in the pic. The tiedown lug (shown) rivets to the other 3 holes, but sticks out and is a helluva nuisance on the bench: I won't be riveting mine until just before painting.

 

Note that the triangular plate goes under the long one, with the rivet heads on top. This all matters, as it's a squeeze.

 

 

 

[IBob]

Cleko this assembly in place. And you can now fit the mainspar rivet that passes through this assembly.

 

 

 

 

[IBob]

Next is the strut stub inspection hatch.

 

The rivets here are left out to allow the C shaped doubler SA150 to be fitted round the inside edge of the hatch hole:

 

Take out mainspar clekos as required, position SA150, cleko in place.

 

Put clekos back in mainspar.

 

And that's it: complete riveting out to the wingtip.

 

Just don't use domed rivets as I did there: the ones under the hatch need to be countersink...dammit!

 

 

 

 

[Guy s]

Looking great Bob and glad to see your making good progress.

 

 

[IBob]

Looking great Bob and glad to see your making good progress.

Thanks Guy. The second wing (and tanks) sure go faster. As they say, by the time you've finished building it, you'll know all you need to build one!

Next, flaperons. Then the big bit in the middle.....................)

 

 

[Guy s]

I really enjoyed building the Fuselage and how it all went together and took shape and reckon your going to love building the big bit in the middle Bob.

 

 

[fallowdeer]

Go Bob. Very inspiring!

 

 

[IBob]

Solid riveting:

 

The solid riveting relies, amongst other things, on holding the tool straight for every rivet. Unfortunately, I have never been overly good at eyeballing 'straight' with tools. To even the odds:

 

I borrowed a good squeeze from a local LAME, and bought the correct AN470 AD3-3 die to go in it.

 

I bought 1/4lb (gotta love those imperial measures!) of AN470 AD3-3 rivets. That's them on the right, with head shape to fit squeeze.

 

First I set up the tool to give correct amount of squeeze: this one just screws in and out.

 

I then set up the wing raised and over the edge of the bench, so that the bench edge acted as a guide for the squeeze.

 

This way, with the squeeze rested on the bench edge, the 'fore and aft' angle of the tool was the same for every rivet. All I had to do then was ensure the tool was straight up and down when viewed from behind.

 

Cleko every 3rd hole. I did not clamp or support the trailing edge, but checked very carefully as I went. The TE is dead straight.

 

It went easily, with no misfires, and I am very happy with the result.

 

Thank you, Guy and Peter, for your help and encouragement.

 

Coming soon: tanks and wingtip.

 

 

 

 

 

[eightyknots]

Great progress Bob. I can't wait to see the fruit of your labour soon.

 

 

[IBob]

Thank you, Eightyknots.

 

And two small comment to add to all the above:

 

1. Check the join between the two lower trailing edge skins: one of them has a small 'tongue' that should be tucked under the other at time of fitting.

 

2. Having positioned these skins, cleko the trailing edge (where the solid rivets will go) before blind riveting along the rear spar. This helps to provide best alignment of the trailing edge holes for fast solid riveting.

 

 

[IBob]

I should have called this thread just plain 'Wings', as i keep adding other wing bits and pieces to it. Here's another one:

 

Fitting Wingtips.

 

I have the full length f/glass wingtips. The following uses info from Kyle Communications build thread, also from Mcrowley in Texas. Thank you both.

 

Unfortunately I have almost no pics of this, but it's simple enough to describe. Here's how it went for me:

 

Setting up the wing.

 

1. Wingtip upper, lower and nose skins fitted and cleko'd.

 

2. The nose and upper skin edge curves are not perfectly matched. Trim and file.

 

3. Trim back the skin stiffening strips so they are approx 2mm proud of the top skin.

 

4. Rivet all skins except the side and rear of the lower skin (that is, only the front of the lower skin is riveted, the side and rear edges are cleko'd. This skin is curved at the rib, but flat at the wingtip and is best riveted after the wingtip is fitted.)

 

2. Leave our last two solid rivets at the trailing edge.

 

 

 

 

[IBob]

Prepping the wingtip:

 

1. Install fastenings for wingtip strobes etc, if required. I used floating anchor nuts.

 

2. There is a square point at the front of the wingtip, which will sit behind the front skin. Round this off.

 

3. Mark approximately where the skin stiffening strips will meet the wingtip. I chose to fit the tips with these strips inside the fibreglass, so sanded inside the tip edge at these points to allow easier fitting.

 

 

 

 

[IBob]

Setting up the wing & inserting the tip:

 

1. The wingtip is flat along it's bottom edge. I set up the wing on blocks so that the lower skin/s are held flat.

 

2. I shaped by hand the leading edge skin, checking it repeatedly against a plywood pattern (taken from a nose rib). I found this easiest to do by running my hand from the last outboard wing rib to the tip of the skins. This takes some care and a few minutes, and I kept at it until I had a near perfect fit.

 

3. I next trial-fitted the wingtip. You need three hands for this, plus a steel rule to get all the stiffening strips past the edge of the f/glass. I found it easiest to get the bottom part in, then work with the top. The whole wingtip needs to go well in to pick up all the rivets.

 

4. I then used a strip of wood inserted at the wing trailing edge, to push the wingtip forward.

 

5. With the wingtip now in place, I checked the fit. With both my wings, I then removed the tip and made further adjustments to the leading edge shape.

 

6. Once happy with the fit, I drilled at the leading edge and got the first cleko in, then worked back along the top then the bottom of the wing, trying always to keep the skins flush to the wingtip.

 

7. Rivet tip, rivet bottom tip skin, solid rivet last of trailing edge.

 

Sorry the pics are fragmented and the last 3 are upside down.

 

I think this method relies on getting a very good fit between skins and wingtip before drilling, as the best way of getting a neat installation.

 

It would also be possible to leave the wooden former in (as per Kyle Communications thread), drill and cleko, then open again to remove the former.

 

And no doubt the professionals do it just as well in a faction of the time...)