TE build method?

[Gaz Reed]

 

I am a new builder with a Flair Magnatilla kit.I am a new member with a couple of questions posted already about the Magnatilla but i think this is more general question on TE build up.

I have seen a method where the top TE piece is chamfered to meet the bottom piece,this looks to me to end up with a TE the thickness of on strip due to the chamfer.I am going to attach a drawing so it makes more sense.

But the palns for the Magnatilla show the two TE pieces with no chamfer at all and kind of "butt joinning" with little contact area.And this also gives a thicker TE because of the two full thicknesses of TE strip.Again i have attached a picture from the plan.

Can anyone advice what is the correct OR prefered method method.If it is the second method like on the plan how is a good join made with so little contact area.It looks basically like two corners touching.

Edited By Steve Hargreaves - Moderator on 26/07/2012 14:57:38

[Bob Cotsford]

With a built up trailing edge I would chamfer the lower TE strip to match the top of the ribs once they are in place and lap the top strip onto the bottom leaving the TE the thickness of a single layer, but you are building a Flair kit, so 'correct' or preferred' don't really come into it. I don't think Flair design the TE as a structural member so all it has to do is hold the covering tight. IE - a good joint just doesn't enter the equation.

 

edit - I'd also web the front of the trailing edge to close the open V

Edited By Bob Cotsford on 26/07/2012 14:17:09

[kc]

I think both of you missed the triangular trailing edge part No 50. This seems to be a solid balsa machined TE section.

The length & shape of the ribs will determine whether a solid TE is used. Personally I make ribs to notch into the TE as it's easier & quicker.

Edited By kc on 26/07/2012 14:42:27

[Richard Wood]

Part 50 is a reinforcing piece of solid TE in the centre section to take the

load of the nylon wing bolts.

Gaz have you considered scalloping the TE? it looks good & is worth the

effort.

[Gaz Reed]

Richard,You are correct in that part 50 is used in the centre section alone ,at the wing bolt.

I would love to attempt scalloping but being my first build i might have to leave that,The funny thing is the plans show scallops and template for tail surfaces but nothing shown for wing!

So can i just clear this up,for the Magnatilla at least.Do i chamfer for a thinner TE ,OR go with the flair Diagramme and butt leading to a thicker TE.apx double that of the chamfered,by my reckoning at least.

I am about to attach another photo,sorry,just to make sure i get this pont across correct.

The are arrowed with star will have minimal contact,corner edge to corner edge.would you run CA along that the sand both faces untill vertical/flat upright?

[Richard Wood]

Gaz,

Because of the relatively shallow angle of the TE, in practice the glueing

area will be quite a bit more than just the starred point in your diagram.

When I built my Magnatilla all I did was to gently sand the lower TE a little

to blend in with the ribs & simply glued the top TE onto the lower with no

chamfering - as per the Flair diagram.

I did use PVA though & not CA.

When dry sand for a neat edge - which will be almost two TE sheets thick.

But there's no reason why you couldn't chamfer it if you wish

 

 

Edited By Richard Wood on 26/07/2012 16:10:28

[Richard Wood]

Same method on my Legionaire wing :

TE is just sanded to a flat edge.

[Gaz Reed]

Richard,Many thanks for the how-to and the picture,it really helps.I think i will go the same method as you discribe and not the wide chamfer on top TE piece like i drew.

Looking at my plans there is a discrepincy in how much the ribs fall on the TE .I will need to move the TE forward somewhat to get the same gap.In your method is it best to have the ribs almost to the rear OR gap apx same as plan. Apx 5mm i think?

[Richard Wood]

Gaz,

Small discrepancies like this seem to be part & parcel of kit building

& often a little compromise or two is needed here & there.

I tend to pin the lower TE strip to match the wing plan's rear outline

rather than trying to match it up exactly to the ribs - the position of the

ribs is of course determined by the lower main spar pinned to the plan.

A 5mm gap between rear of rib & rear of TE seems quite a bit but may be ok.

Trial fit the top TE sheet & see how it looks - a little gentle sanding here &

there can improve the fit if necessary but a small gap at the rear is probably

acceptable as long as the assembly is generally sound.

If you're concerned about a gap use epoxy here as it is an excellent gap filling

glue.