Savannah S Build Notes - Stabiliser

[IBob]

Pre-amble (Walk Slowly First?):

 

DIYer, no formal workshop background, greatly enjoying getting into my first build.

 

There is a goldmine of info on this site, plus a lot of knowledeable and helpful people to ask questions.

 

What I thought I could leave is a brief record of the bits I stumbled on.

 

My kit was manufactured December 2014.

 

Comments and suggestions welcomed.

 

Always.

 

The Stabiliser:

 

1. From the outer ribs to the wingtips, the leading edge rivet lines are unsupported. That is, you are riveting skin to skin and nothing else. While this is not a structural problem (or they would have done something about it) it means this area is vulnerable.

 

It turns out that various builders have added their own simple strengthening at this point. I wish this had occurred to me.

 

2. The fittings to the back of the rear longeron have changed. The centre plate is overbent, making it very difficult to rivet, at the sides, from the outside.

 

One builder here has managed with an angled spacer bead on the rivet mandrel. I chose to rivet the edges from the inside.

 

I suggest fitting all external parts, front and back, before starting on skins.

 

3. Only install the elevator hinge SD020 at the Right wingtip at this stage. The Left one goes on once the elevator is attached.

 

 

 

 

[IBob]

4. Consider which method you will use to mount the plastic tip before riveting skins to top rib: some builders sandwich a strip of aluminium between skin and rib to give fastening for the tip.

 

 

[IBob]

And I am going to have to learn to think ahead:

 

At this point, having fitted the plastic tips to the Fin and Rudder, I fitted them to the Stabilizer.

 

Then, having fitted them to the Elevator, I had to refit the Stabilizer tips again, for correct clearance.

 

So, first (temporarily) assemble Elevator to Stabilizer, with appropriate bushes and washers at wingtips (the centre pivot is not yet bored out, so I just eyeballed it for alignment and clearance)...

 

next, fit Elevator tips to an allup max width of 2430mm (which is the allup max Stabilizer width minus 10mm each side for clearance).....

 

Now fit the Stabilizer tips. Since I had already (incorrectly) fitted these, with excess clearance, I was able to remove all but the front Clekos, swing the tips in for correct clearance to the Elevator tips, mark cut ends top and bottom with masking tape, then just slice off a long wedge with the straight edge and craft knife.

 

I wonder what you use to bung up holes in plastic?

 

 

 

 

 

 

 

[eightyknots]

Perhaps a paintable silicon-based filler?

 

 

[IBob]

The centre pivot point for mounting the elevator to the stabiliser is not drilled out to the final size for the bush.

 

Some adjustment to the position of this hole may be required: drilling out to bush size is best left until assembling elevator to stabiliser.

 

 

 

[MajorTom]

The Stabiliser:1. From the outer ribs to the wingtips, the leading edge rivet lines are unsupported. That is, you are riveting skin to skin and nothing else. While this is not a structural problem (or they would have done something about it) it means this area is vulnerable.

 

It turns out that various builders have added their own simple strengthening at this point. I wish this had occurred to me.

Could you be more specific? What means vulnerable?

 

I could imagine riveting a little L-shape stiffener under the two skins.

 

192.168.0.100_069629.pdf

 

192.168.0.100_069629.pdf

 

192.168.0.100_069629.pdf

[Kyle Communications]

Look in my blog you will see where I made up strips to go under the elevator stab skins where they are unsupported

 

 

[Kyle Communications]

Post 159 shows the strengthener

 

 

[MajorTom]

Another NEW Savannah XL on its way

 

That's what I thought. Nice, but how did you get the extra stiffners, or better how do I get some. Is there enough aluminium to salvage? Maybe cutouts? I don't remember, if there where cutouts for the tank covers. If yes, they are not needed elsewhere right?

 

 

[IBob]

Another NEW Savannah XL on its wayThat's what I thought. Nice, but how did you get the extra stiffners, or better how do I get some. Is there enough aluminium to salvage? Maybe cutouts? I don't remember, if there where cutouts for the tank covers. If yes, they are not needed elsewhere right?

If you have the extra fuel tanks, then some of the main wing stiffeners will not be used, and you can use them.

Otherwise, yes, there are cutouts in the wing skins where the tanks go, and they are surplus material that can be used.

 

Now I am experienced at removing rivets (and you will be too!) I am going to open my stabiliser and fix this.

 

 

[IBob]

4. Consider which method you will use to mount the plastic tip before riveting skins to top rib: some builders sandwich a strip of aluminium between skin and rib to give fastening for the tip.

The difference between using a sandwiched aluminium strip, and using the 'petals' provided in the kit is that the petals allow you to set the plastic tip exactly flush with the stabiliser/elevator skin.

With the sandwiched strip there is likely to be a small step where the tip meets the skin.

 

 

[IBob]

When I open my stabiliser to add stiffeners, I will also re-route the wiring for the trim servo: the manual shows it running along the rear longeron, but other builders have run it along the front longeron, which will be neater.

 

 

[Kyle Communications]

Bob is correct. I used the unused wing skin stiffiners as I had the exttra 2 tanks so that made the stiffeners obsolete and I used them in the stab

 

 

[MajorTom]

Now I am experienced at removing rivets (and you will be too!) I am going to open my stabiliser and fix this.

That I'm sure of. But I have not put the skins on yet.... So thanks to your great help, I dont have to drill out anything. The fact, that you want to reopen you stabiliser showes me, that doing the mod is worth it.

likely to be a small step where the tip meets the skin.

I'm thinking of using the plastic tips to make new tips from glass and epoxi. They should be thinner... so no big step I hope.

@Kyle Communications One more question: You started with the stiffener on the last rivet betwen the 2 sheets an the longeron, right? Doesn't that make a bump, where the "unexpectet" material starts? What about putting a shorter stiffener just were there is nothing under the sheets?

[Kyle Communications]

If you do that then you wont get any stiffness over that distance. The stiffener needs to be anchored at either end. You could put that stiffener under the rib edge but it would make it difficult to make sure you got the rivet in. It didnt seem to matter on my tailplane that I put them on the top of the rib. Yes there maybe a small raised bit but the skin will follow that anyway. I dont notice anything on mine at all with the tensioner being there

 

 

[Kyle Communications]

You have the same thing with the wing skin tensioners when you build the wings. They go on the top of the wing ribs

 

 

[MajorTom]

Thank you very much Kyle. Your infos are always very helpful.

 

Yesterday I unpacked my wingskins and salvaged the cutout of the tankcover. Can't beleave this big peace of alu-sheet is over.

 

Making stripes were super easy. I used a carpet knife. 3-5 passes and bing.... a perfekt stripe came of. Will try bending over the table edge.

 

 

 

 

[MajorTom]

This little stiffners are just 66 gramms together. One is used to attach the trim servo cable.

 

 

 

 

 

[Kyle Communications]

looks good :) the sheet you cut it from is only 0.016 inch so shouldnt weight much just so much stronger with that right angle bend