Cessna 180 Group Build

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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:21 pm

I always like to “mock” up the frames to see if all is well at this stage, and to get a sense of scale for the model and spot any potential downstream issues early.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:23 pm

Covering and preparation for covering are both subject areas that are open to a very wide variety of techniques and thus opinions.

I will be covering the fin and tailplane first, as these are relatively easy but will show some of the techniques and consumables I use. The pictures may show either the tailplane of fin, but the techniques apply to both.

I will of course show the way I do things, and this might not be the same as what you might have seen elsewhere, or are comfortable with doing. There is no right or wrong way of doing this, just the way you like best.

Give the frames a sanding all over with nice fine paper, around 800 grit wet or dry if you have it. This won’t remove much wood but will begin to make the surface smooth to the touch.

Next we will seal the wood where we will glue the tissue to. This stops the grain being raised by the glue, helps to strengthen the joints and makes a nice smooth surface for the tissue to slide over to pull it tight if required.

I use a product called “sanding sealer”. This is simply cellulose dope with a fine filling powder in it. I believe from what I’ve been told that it is talcum powder mixed in with full strength cellulose dope, or at least that will do in lieu of the real thing if you can’t get it. I have used just dope before and it is worked ok, so take your pick.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:24 pm

We will only be sticking the tissue to the very outside profile of the frames, so give both faces a good coat of the sanding sealer, giving the joints a brush too, don’t forget the very edges.
Prop the parts up whilst they dry, here is the tailplane coated, I think that in the picture you can see the coated areas as those that are slightly darker.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:26 pm

Give the parts about 30 mins to dry, then use 1000 grit wet or dry, this makes the wood very smooth and ready to be covered.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:27 pm

I use thinned white glue (PVA)to attach the tissue. This is roughly a 50/50 mix of glue and water. I make this up in a sealable pot so I can mix a small batch without wasting any.

The tissue supplied in the kits doesn’t really have a “grain” - some tissue does, some doesn’t. The white tissue is the normal basic Guillows stuff found in the smaller kits. However the grey seems slightly better quality and seems to have a slight sheen to it.

Cut out pieces that are larger than the part by at least ¼” or so, using the layouts on the plan as a guide, choosing the correct colour tissue. Once you have done this hold the tissue flat to the board with some weights, this makes the next step easier. Then apply the thinned glue to the perimeter of the part, then plonk it down on to the tissue.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:29 pm

Remove the weights and smooth the tissue out gently with your finger. It is a good idea to have a sponge or old cloth handy to keep your fingers clean whilst you work.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:30 pm

Give the glue 10 -15 minutes to dry, then begin to trim the tissue. I have found that the very best thing to use to trim the tissue is a blue steel razor with a back as shown in the very first post.

With the bottom of the fin only, trim the tissue flush with the edge of the wood. On the other edges cut the tissue leaving around just less than 1/20” all the way round. This is halfway through:
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:31 pm

And this is the fin trimmed all the way around:
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:33 pm

On the external corners, cut a little square out as shown, this allows the tissue to be folded over neatly.
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Re: Cessna 180 Group Build

Postby ADW 123 » Sun Nov 20, 2011 5:34 pm

Phugoid, if you could, take a picture of how much glue you are setting down on your parts.

Happy 1000th post....
Last edited by ADW 123 on Sun Nov 20, 2011 5:35 pm, edited 1 time in total.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:34 pm

On the curved edges cut a series of “tabs” into the tissue thus:
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:37 pm

Once you have done all of this run glue along the edge and carefully fold the tissue over, in the picture you can see the tissue going a bit wrinkly due to the water in the glue...
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:38 pm

Continue all round securing all of the edges.
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:39 pm

Repeat the process on the other side of the frame, then leave things for a couple of hours to dry fully.
Next we need to shrink the tissue with water. To apply the water I use a cheap plant sprayer, this one was 99p ($1,50)
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Re: Cessna 180 Group Build

Postby Phugoid » Sun Nov 20, 2011 5:40 pm

To avoid over soaking the tissue (and warping the wooden frame) do not spray the water direct, Instead the best way to gently dampen the tissue is to spray a mist of water in the air, then waft the part through the misted air, do this a number of times until the tissue begins to look damp and wrinkly:
Last edited by Phugoid on Sun Nov 20, 2011 6:00 pm, edited 1 time in total.
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