OOLILISSIMA

I have started this thread to discuss my attempt at a scratch-built scale Auster aircraft from, as far as I can, discarded materials.

I know that recycling and adapting discarded materials and components is nothing new in modelling. However, I am using the project to see just how much of such a large, flying model I can build from such materials.

Having already spent some time experimenting and developing methods, and indeed collecting established ideas thought up by others, I am pretty confident that I can build about 75% of the model "from the bin" without compromising strength, durability or other performance as compared with a similar, balsa-based professionally marketed model. This is despite the fact that the airframe will be built principally out of corrugated cardboard.

I have therefore started designing in earnest. For some months, I have been (making a nuisance of myself) scrounging cardboard and paper for the airframe and covering respectively, litho plate for the cowl and other details, aluminium tube for the struts and other bits and pieces.

The volunteer Auster specialist at the Leicestershire, Leicester and Rutland County Councils' Museum Service Records Office has been really helpful in providing selected extracts from the Auster company's factory drawings. The Newark Aircraft Museum have also been very accommodating in allowing me to photograph G-AGOH (which, coincidentally, also belongs to Leicestershire, Leicester & Rutland Museums). I hope shortly to post more of my photographs of G-AGOH on the forum.

I had originally decided against modelling G-AGOH as it is a military-style observer aircraft having a canopy that stretches from the cowl at the front to well beyond the wing trailing edge. This was because I believed that making the aircraft structurally sound in cardboard would prove impossible. However, I am finding it easier than I thought to combine the cardboard with other materials, so I now regard it as a challenge to be met.

I'll reserve description of a building methods etc. for future posts, preferably with photo's from the project. In the meantime, I'd be really pleased to hear from others with ideas or remarks.

wonwinglo

Paul,I take my hat off to you,you are doing just the things that make a model builder unique,building from scrap is a wonderful idea and something which I just wish more people would try,here are a few pointers for you to exploit and experiment in this direction,card flying models are nothing new by the way,as we had a kit manufacturer make a radio control trainer from commercial card used to make packing boxes,here are a few tips-
Sure use corrugated card by all means,plan the fuselage by using the outline drawing to hid a 'box' within,from around this basic box add the side formers from just aft of the engine bulkhead to the sternpost of the tail,so what we have in effect is two sides for the fuselage minus the decking,undersides and top plan view side formers,in fact if you study the full sized Auster you will see that it is basically a welded steel frame with wooden side pieces added,then stringers,so copy the lines of G-AGOH and you will not go wrong.
Once the basic box has been glued together now consider removal of surplus card to save weight,especially around the tail area,to do this go to your local supermarket and buy a set of pie cutters,these are stainless steel metal discs used for cutting pasty,seriously dont laugh because you have the idea thing to remove surplus material,just dress up the outer edges with a warding file and place the cutter against the card,use a swirling motion and see the cutter start to remove the excess,you can clean the hole up with glasspaper wrapped around a piece of broom handle,thick card sands very well.
Consider buying a bundle of balsawood offcuts,these cost a few pounds and provide a lot of wood for your money,this can be used to bring out the fuselage shape with those vital formers,you can also use a bit around the nose cowl area overlaying the card underpan for the engine,plus the card side pieces for the engine as well,for the nose cowl make a blue foam plug ( scrap from any builders site,it blows around in the wind ) then make a paper mache nose cowl using brown paper and PVA glue,three layers baked in the oven make for a tough nose cowl,dig out the surplus material with a round chisel or potatoe peeler,or even pour thinners to melt the foam from the plug.
Wings can be also made from card,there is a special way to do this,if you are still interested to pursue your exciting project from card etc then I will deal with the wings and tail next time.
Another excellent source of scrap material not to be overlooked is Depron foam used to make those pizza bases and also for supermarket meat plates,basically toughened foam outer skin it can be cut with scissors and glued with PVA or even now special odourless cyno,it can be easily built up onto a card base.
So get cracking and cutting that card to make a super Auster project,it will succeed because you have your heart set on that particular aeroplane,best of luck.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

OOLILISSIMA

Wonwinglo wrote:

I hope you are not speaking too soon, Barry!! Still, I have at least made a start. Now, it's a question of commitment, etc...

Many thanks for the tips. It sounds as if you've done this before.

Yes, I had realised that there were already corrugated card flying models. What I haven't found anywhere, though, is anything on this scale... no doubt, I'll soon hear of some... or I hope so...

Another reason why I like large scale modelling is that it is much more foregiving. For example, an error or inconsistency in cutting a rib shape will have a much greater effect on the flying characteristics of a small-scale model, whereas it may well have no noticeable effect at 1/3 scale.

Having said this, one of my reasons for "going large scale" is the vastly greater scope for incorporating recycled materials and components. For example, at 1/3, or even 1/4, scale, the model can be covered entirely in 80gsm paper (taken from potato bags or from supermarket sugar stacks interleaves) backed with plasterer's scrim stuck on the back with 50% PVA/water, shrunk on - it forms a very authentic "linen", and superb scale pinked tape and rib stitching are very easy to make. This sort of thing is much more difficult - because of the weight - with small-scale models. So is using modified engines. At this scale, I shall be able to use a second-hand two stroke mini moto motor.

Thinking through how to achieve this, making up the test pieces to see what can be done, etc. all makes for an interesting exercise.

Oh dear, does this mean I'm turning into an anorak...

OOLILISSIMA

In my most recent post, I said to Wonwinglo:

That has turned out to be a real understatement, Barry. I've since visited your web site, of which I wasn't previously aware. It's not far off all one could need know about the subject. It's brilliant!!

wonwinglo

Here are some more ideas to think about and spur you on-
Walk the streets for discarded Estate agents signs,they are made these days from Correx board,now this really is useful stuff for making those wings,it is rigid and will bend to a Clark Y aerofoil shape as in your Auster,even if you make up corrugated card wings this is how to tackle it,firstly cut out the plan form of the wing shape including the wingtip which will be bent upwards after scoring,next glue a wooden leading edge ( unshaped at this stage ) you can use hardwood because this will act as your spar and also where you can attach brackets to fix to the fuselage ( a good way is to make pin point brackets whereby a piano wire rod passes from the front ) then the struts hold the wings with the correct dihedral angle etc,next cut out some stout ribs fixed at strategic points just aft of the leading edge but allow for a wooden trailing edge ( you could possibly butt the sheet upper surface right up to the trailing edge,but from past experience this looks a bit on the thick side ) next sink another narrow leading edge piece just deep enough to take the top sheeting for the wing,a good adhesive for this is Thixofix contact adhesive,you apply it,allow to dry and then fix the covering from the leading edge,carefully rolling it over the ribs until it meets the rear,quicker to do than describe.
Ailerons are best cut out later,if you have a bandsaw then ideal,once cut out undersize them to allow for the leading edge piece which could be top hinged,you could also allow for the differential at this stage ie more up aileron than down,this is very important on high wing designs as it stops the horrible aileron reversal which even early Auster aircraft suffered from.
Reinforcement at the spar joints is best made with epoxy and hardwood trapping the metal wing joiners,make sure that you rough up the metal fittings first so the slow drying araldite gets to grip.
Wing rib tapes can be added from strips of card glued chordwise across the wings leading edge to trailing edge,then you scrim can be PVA'd over the whole lot,this will give you that slight sag in the places where the ribs are positioned,this type of structure is rock solid,I built a Junkers 52 3/m from card this way winding cord around the wings to get the corrugated effect,it flew successfully on a single engine with the two outboards just windmilling along,I may build another one day for electric.
You mention if I have built large models from card before ? loads of them,after all it is still the cheapest material around and is tough and does not shatter like balsa does.
Think also of exploring foamboard,a great modern material made from foam laminated either side with thin card,it is expensive by comparison with freebie card packing cases,but there again is often discarded from exhibitions etc and can be found in skips,the lettering applied is of no consequence as it can easily be painted over with artists acrylic paint.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

OOLILISSIMA

Barry, thanks very much once again.

I actually had heaps of Correx that I begged from estate agents when I was a surveyor, but it seemed I was never going to get time to do any modelling, so I let it go a couple of years ago. Of course, I now regret it. Having said that, I do like the idea of making this essentially a paper model.

In fact, the Auster J/1 Autocrat and Mk 5 both have the NACA 23012 aerofoil which, as I expect you know, is slightly harder than Clark Y to build on account of its curved bottom.

I have developed a different method for constructing the cardboard wing. It is essentially similar to a traditional built-up balsa wing. The strength and lightness are very surprising to people who have grown up thinking that cardboard is weak and heavy. That's quite odd if you think about it: for it has to be strong to protect the goods and be stackable, and it has to be light for handling and transportation.

I glue (approx. 50:50 PVA: water) together layers of corrugated cardboard, totalling about 7.5mm thick. From the resulting sheets, I cut out the rib sections using a jigsaw, which cuts accurately and with the edges of the ribs nice and square to the sides.

The rib flanges I make with Depron wrapped in 80gsm paper stuck on with PVA. I build D-tubes/box sections between the leading edge and front spar and between the aft spar and aileron spar similarly; i.e. with Depron faced both sides with the same paper (of course, sticking the paper on the outer face of the curve stuck after fixing the Depron!) I stick continuations of the rib caps onto the D tube to give the impression of continuous ribs to the correct position (this is precisely as you suggested earlier except that I will not be using balsa). The nose section I make from builder's polyisocyanurate insulation foam (your foamboard?), which is very strong and light - and hard, once the paper covering in in place. Interestingly we seem to have come up independently with practically the same idea here, if I understand correctly your point about sticking card on both sides of a foam component.

I build the ribs in sections, each of which is embedded into the layered corrugated cardboard spars, by sticking on pieces of the outer layers of the web to fit between the ribs. Plywood - from orange boxes - is used to reinforce webs and ribs where necessary; e.g. at strut fixings or servo mountings.

Just to clear up what may be a misunderstanding, the cotton scrim is stuck on the back of the paper covering. It reinforces the paper, and doesn't on its own create the linen effect that I mentioned. That effect is from the surface of the paper itself, with just a light impression of the scrim's pattern showing through.

For rib tapes, the same paper as for the covering, but without the scrim, is ideal . Also, tearing the paper against the edge of a hacksaw blade creates an accurate 1/3 scale pinked-edged over-tape. I may have misunderstood what you are suggesting, but card tapes would be too thick and prominent, even at this very large scale.

I share your liking for cardboard for, among others, the reason that you state; i.e. it doesn't shatter. I also note your points about fixing metal to cardboard. Did you also know that PVA itself fixes very well to abraded aluminium surfaces? My parasol struts will be based on this discovery: the corrugated cardboard will be scored so that it can be wrapped around and stuck to the aluminium tubes, then wrapped in the same 80gsm paper as for the covering (again without the scrim). The cardboard stiffens the metal struts considerably. So much for "weak" cardboard.

While I am further on with my design than you may have gathered, and am already committed to most of my methods, it is good to hear of other ideas. They help me check my own thinking, and they also provide alternatives in case things go wrong.

I will post some photographs ASAP, so that, hopefully, what I have written will become a little clearer.

wonwinglo

Paul,most interesting methods of construction,and all from scrap materials ! welcome to the scrimpers side to model building,great fun as well,modern materials abound in skips and literally in the street,look out also for discarded signs that employ unusual materials,one blew into the garden one day that was made from a lightweight bubble plastic but rigid,I tried a sanding block onto it and it sanded beautifully,but I understand you are talking mainly of card that is understandable,considering its sheer size it is cheap even if you have to buy the odd sheet,ever tried Chipboard ? not the heavy lumber scraps type,but compressed card which substituted the old brown strawboard rarely seen these days,it rips with a bandsaw and can b shaped at the edges with a sanding block,a thinn coat of PVA seals the grain to take car spray aerosols.
To build a tailplane cut out the planform from medium card,add another layer around the outline extending in aprox half an inch,then add ribs crosswise or even geodetic construction for real strength,sand the whole lot up,add re-inforcement at the centre section of the tailplane,cover with scrim faced paper pulling and easing around the tail,flat plate Auster type tails are easy,flying tails with proper ribs also work well,you could use the pie cutter tool to remove excessive material prior to sheeting in with the scrim faced card,results are very tough and surprisingly light,add hardpoints from basswood sunk into the tailplane,search out alloy curtain rod from a DIY store,there is even an aerofoil section that can be crimped up at the ends and screwed into place.
Look forward to seeing any photographs you may already have.
If I had got that job on 'Blue Peter' years ago then there would have been plenty of flying card aeroplanes on television !

Someone described an Airspeed Oxford built entirely from card in the 'Radio Control Models & Electronics' many years ago,he came from Leicester,was that you ?

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/

OOLILISSIMA

Barry, thanks for some more interesting ideas.

No, it wasn't me in Leicester. In fact, I have been an "armchair aeromodeller" more than anything, although I do have previous planes under my belt. My background in building construction and design probably gives me an edge over other modellers who have as little actual modelling experience as I have, and it helps me think laterally to some extent.

OOLILISSIMA

Wonwinglo wrote:

Of course, the ethics of such scrimping is a basis for an entire separate debate. Apart from my real fascination in the practice, it happens that I really do need to scrimp, as I have had years of ill health and have had to retire very early. I know, enough of this canvassing for the sympathy vote... However, I am conscious that every square metre of material I improvise arguably represents a lost sale of one square metre for a model shop proprietor. A salient question is, therefore, where will I find a model shop when I want to purchase my next radio, etc?

Other salient questions include such issues as cutting down balsa trees and saving resources by recycling.

This is, of course, a simplistic representation, but it seems worth mentioning.

wonwinglo

A good point about balsa trees,just as every natural resorce things are slowly drying up,a worldwide shortage of Sitka Spruce as brought forth a whole new breed of carbon fibre light aircraft and kitplanes,there are a few closely guarded sources for timber but it is so expensive,balsa these days is like floorboards,the old graded stuff is difficult to get hold of,even soft means pulp,if you can get hold of balsa teachests then they are the answer,rip down your own wood.
Dont worry about radio or engines or servos,give me a yell when you are ready and I will sort you out some quality stuff at the right price.

__________________
'And there I was oil on my goggles from a broken pipe,then I looked at the altimeter,all I could see was the makers name !'
www.wonwinglo.scale-models.net/