Guillow’s Cessna 180 – part 4, sealing, sanding, covering and initial assembly

The sealing-and-sanding process can’t really be captured in photographs. All it involves is giving the frames a few coats of your chosen substance (a lot of modellers use cellulose dope, I use thinned PVA glue, as I’ve mentioned in previous builds), sanding between each coat, in an effort to seal the wood completely to stop it absorbing glue and water when covering takes place.

Once that’s complete, and dry, and sanded, it’s time to cover the whole damn thing. I often find the easiest place to start is the tail surfaces (they’re flat, so it’s a safe way to get back into the groove as it were).

However, this time things didn’t go entirely to plan, and I managed to warp the tail surfaces (a common problem in my models), so I had to take all the tissue off and start again. Luckily this isn’t a complicated, time-consuming process, so it was quickly done.

The wings were easier to cover and keep straight, though the shrinking of the tissue left a few wrinkles at the point where the ribs meet the leading edge (as you can see in the photo below).

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The fuselage was also pretty easy, though the covering did reveal a problem with the very rear. One of the stringers was too low, which made the attachment of the vertical tail a challenge as the taut tissue was sitting a millimetre or two above the stringer to which the tail should be glued.

At this, the next problem arose: it looked as though the fuselage was twisted somehow. It turned out that it wasn’t, and I’d actually managed to attach the wings with unequal dihedral, which was easily solved when the wing struts were installed.

I think I have made more mistakes with this build than the previous two put together, which is very frustrating and a little dispiriting as this is meant to be a simple build to get kids into the hobby. On the positive side, I think I have solved all of the major problems and I’m starting to understand which issues are important and which are merely cosmetic. My main aim with this model is to get it to fly. If I can do that, I don’t really care how it looks. I want to learn how to build a flying model first and then work on making them prettier each time.

Guillow’s Cessna 180 – part 3, the tail surfaces and wings

The next stage of the build is the tail surfaces. These are pretty simple (hence why I tackled them next) and yet they are also something I am keen to get right. With both the Hurricane and, to a lesser extent, the Mustang I managed to warp the tail surfaces, so I am determined to keep them flat this time around!

The tail wings are pretty basic and look quite sturdy:

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And when they’re finished and placed next to the equally strong-looking fin and rudder:

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The wings are always one of my favourite parts to build. I think they give an aeroplane its character, and stop it looking like a bizarre car. They’re often the easiest way to identify a plane too – a Spitfire’s elliptical wing is probably its most recognisable feature.

The wings on the Cessna 180 are fairly straightforward, though in the Group Build to which  I am constantly referring, it is suggested that there is a slightly complicated modification which significantly improves the strength of the wing. Essentially, it involves making a joint mid-way along the wing stronger by splicing the two pieces used together to provide a larger glueing area as well as other benefits which are beyond my novice’s comprehension.

That stage is pretty difficult to show properly, though it is shown very clearly in the Group Build thread (see part 1 for the link), so here is a picture of the nearly completed wings:

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At this point, I am further strengthening the leading and trailing edges by ‘laminating’ them with a strip of 1/16th” balsa along the entire length. This also helps rectify a small error in the plans which overestimates the width of the pieces used for the leading and trailing edges and so leaves the wing ribs with a slight overhang. Once the lamination is complete, the ribs and edges can be sanded flush for a neater finish.

After this, the whole of the model needs sanding and sealing in preparation for covering!

Guillow’s Cessna 180 – part 2, the fuselage

As I mentioned in part one, I am going to endeavour to make this build a little more stage-by-stage than the Mustang build was.

Nearly all model aeroplane builds begin with the fuselage to one extent or another. This isn’t the first stage on the plan, but it’s where the build starts in the Group Build (mentioned in part one) and I’m going to follow that as closely as possible.

To start with, I weighed the wood sheets which contain the parts. Mine came out at just over 24g.

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Then I started gluing the pieces for the fuselage together. This fuselage is built the same way as the Mustang (with the two sides built and structure going in between them) instead of the same as the Hurricane (keel and formers glued together and stringers attached to the outside).

Here are the fuselage sides as the glue dries.

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Here are the sides with the various braces added:

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As you may notice, the pins have changed position. This is because this is the moment I made my first minor mistake. I pinned and glued the major parts of the fuselage sides without thinking about the structural braces. This meant that in order to see the precise positions of several of the braces, I had to remove the sides from the plan. What I should have done was cut the braces to size and lay them out appropriately before I even thought about laying down the major parts.

The next step is to glue the tail end together and then attach some of the major fuselage formers. The key is to get the formers as square as possible to prevent the fuselage warping. I failed in this respect and had to break the tail end apart and reattach it.

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Even then, after adjusting the fit of the major parts several times, I am not convinced that I have got it perfectly square. A poor workman blames his tools, but I think the kit leaves a little to be desired in terms of fit and the quality of the wood used. One of my minor adjustments turned into an awkward and time-consuming repair as I ‘adjusted’ the piece into several smaller pieces. The joy of balsa modelling as opposed to plastic kits is that it is much, much easier to make a replacement or repair a broken piece.

I have also found the style of construction in the last two kits (the box fuselage instead of the former and stringer method of the Hurricane) less to my liking as I think the whole plane feels less sturdy this way. The next kit I build will definitely be a laser-cut kit which should make the engineering and fit of the parts much better and allow me to get on with getting the basics right in other areas, like the covering.

After a lot of fiddling, I eventually ended up with a fuselage with which I was grudgingly satisfied.

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Guillow’s Cessna 180 – part 1

My next balsa aeroplane is going to be a little different. So far I’ve built two World War 2 fighter planes with varying results. One looks quite nice but flies like a stone while the other looks terrible and is yet to be tested in the air.

A little reading about the models I’ve built and some basic aerodynamics has suggested that I’m going about this all wrong. Free flight planes fly slowly and need stability to avoid stalling/flipping/rolling and ultimately crashing. I’m trying to build flying models of planes which were designed to fly very fast and with an element of instability to make them manoeuvrable, when really I should start with something slow and stable like many of the private planes around today. Therefore, I am going to build the Guillow’s Cessna 180.

A real Cessna 180 in action

I have chosen this particular kit simply because, on the official Guillow’s forum, there has been a Cessna 180 ‘Group Build’ (where several people build their own version of the same kit simultaneously whilst discussing the problems they faced and their solutions) with the explicit intention to help newcomers such as myself to build a simple and straightforward kit which should fly reasonably well.

So here’s the kit:

Guillow's no. 601 Cessna 180

Guillow’s no. 601 Cessna 180

The contents of the box look like this:

All the pieces laid out on my building board

All the pieces laid out on my building board

There are several things here which impressed and pleased me more than in the other kits (though this could be because the other kits were more sophisticated and designed for people who could do a lot of this for themselves…). Firstly, the undercarriage wire is pre-bent into the correct shape, there is a lump of clay for weighting the nose, the instructions are much clearer regarding the order of construction and the rubber looks better quality than the previous rubber bands supplied.

So, in the next few days I hope to make a start on this (and build a model that actually flies!) and I will attempt to keep a more coherent build log than the last one. I have also invested in a new digital camera which should improve the quality of the photos too.

Balsa Wood Mustang, part 4

After some fairly ineffectual faffing about, I decided that the only sensible way to repair the minor damage to the tail would be to brace it with some scrap balsa on the outside of the fuselage, and take the undesirable weight gain on the chin. Below is a picture of my solution to the problem.

Obviously, this could incur some sort of weight penalty and negatively affect the flying performance of the model. However, recent browsing of the Guillow’s forum suggests that the 900 series models (of which which this is one) are designed very light anyway so adding a little extra weight isn’t a problem.

After that, all that remained was to ‘dope’ the wings, and put it all together!

Afterwards, it looked something like this:

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I’m rather pleased with the attachment of the canopy, even though it won’t be particularly clear from the photos. In the past, I have had problems with clear parts fogging up from glue fumes and was more than a little apprehensive this time. However, carefully tacking down the canopy in the corners with superglue and allowing it to dry before running a tiny amount down the edges seems to have worked a treat. Hopefully it’s all down to technique rather than good fortune!

Aside from that, it’s a pretty ugly model of a rather attractive aeroplane. As you can see, the covering on the wings isn’t as smooth as I was hoping and the glue has left dirty stains on the tissue covering. Hopefully, it will be a triumph of function over form.

At this point, it still needs a couple of fairings added to the wing roots, and I’m considering giving it a quick coat of silver acrylic paint. That may prove to be a disaster, but I won’t know until I try!

Balsa Wood Mustang, part 3

During the covering of the wings, it became clear that the left wing was better built than the right. (There’s a point on the wing where there are two ribs side by side, and on the left wing they are identical, but on the right one rib rises a millimetre or so above the other towards the trailing edge of the wing.) Hopefully this won’t cause major problems. If it does, there is a solution – namely, strip off the tissue, sand level and re-cover.

After all of this came the shrinking stage. I had already been advised to leave the tail surfaces out of this and simply to seal them with the glue and water.

I shrank the fuselage, but unfortunately the tissue was quite slack in a couple of areas (due to some sloppy covering I expect) and so there are some wrinkles in the tissue even after shrinking.

At this point, things started to go slightly wrong.

Firstly, whilst sealing the tail surfaces, the tissue from either side stuck together. After posing the question on the Guillow’s forum, I was reassured that it won’t affect how the model flies, but it has left dark, translucent patches on the surfaces which mean that even before construction is completed, it looks grubby.

Secondly, after spraying the wings with water in the bathroom, I carried them back to Construction Central (also known as the spare room) pinned to my cork board. Watching the board carefully so as not to damage the wings, I sat down on the bed…. and also on the tail end of the fuselage. D’oh! Luckily, the fuselage itself was virtually undamaged, but I did manage to break the cocktail sticks I was using as a peg to hold the rubber band motor in place, and also weaken the mounting hole.

However, this was not the end of the problems. Reinforcing the hole with scrap balsa would potentially add too much weight behind the ideal centre of gravity, so I decided to drill myself a new hole a few millimetres away from the old one. I was smart enough to realise that the original hole was placed where it was to benefit from the nearby fuselage former so I decided to place my new hole in a similar position. However, despite measuring carefully, I clearly didn’t do it carefully enough. After drilling the new holes I inserted another cocktail stick only to find that it wasn’t level when viewed from above (one hole was nearer the tail than the other. The problem with this (I think) is that as the tension increased in the rubber band during winding, it would slip to the side nearer the nose and increase the stress on the wood on that side and probably tear a wider peg-mounting hole.

At this point, I feel as though more has gone wrong with this build than with the Hurricane. I’ve certainly made more mistakes. This is pretty frustrating considering that I had set myself the lower target of simply trying to make it fly, rather than look like a beautiful model. It will be quite an achievement to get it all completed and balanced at this rate!

Balsa Wood Mustang, part 2

After a prolonged, enforced break caused by the wire provided for the undercarriage proving too hard to cut, the build is back up and running! A new pair of wire cutters were purchased and the main undercarriage cut to size.

However, after some thought, and reading some forum comments against including the undercarriage on a flying model, I decided against adding the wheels. All that unnecessary delay! However, in the intervening period I had done a fair bit of reading on the subject and so the time wasn’t completely wasted.

With no wheels to prepare, all that remained before covering and final assembly was the sealing of the wood with the 50/50 PVA/water mix used on the Hurricane.

Unfortunately the rudder sustained a small amount of damage during sanding and required some very basic repair work.

After that came the covering. First of all the tail plane:

Then the rudder:

Then I thought about getting a bit clever and attaching the wings part way through the covering process as leaving certain parts exposed would give me easier access to clamp the wings to the fuselage while the glue dried. However, posting this idea on the Guillow’s Model Builders’ forum (yes, they have their own dedicated forum!) was met with general disapproval. Apparently, the wings need to be fixed to a flat surface while they dry after the tissue is sprayed with water to shrink the tissue, otherwise there is a serious risk of the wings warping.

(At this point I should probably clarify that I have decided to use this model as a ‘proof of concept demonstrator’, that is, function is everything . Therefore, the undercarriage has been sacrificed to save weight, and decals will be omitted to reduce the need for preparatory coats on the model for much the same reason. Ultimately, the model may not look like much but it should work as well as it possibly can.)

So, I completely covered the fuselage:

And then made a start on the wings:

Once these are all covered, the tissue will be shrunk and then ‘doped’ (I’ll be using the usual PVA/water mix) before final assembly.