Let's Go Retro: Shaping and Scraping the Zeppelin Lindau (Dornier) Rs II (late)

[hendie]

wot they all said !  (okay, it's a cop out I know but...)

[pheonix]

Thanks to all of you for the very generous remarks. I am a little relieved that I managed to get this one right: now I just have to get all of those holes in the right places!

 

P

[pheonix]

I have decided that as showing a photo of the hull coated with talcum powder and dope filler would not cause much excitement I will move on to the wings. These are to be made from halves of 3 x 60 thou card sheet which has been laminated. These need to be scraped and shaped so:

Scraping and Shaping 4: Wings. I used the flat file again to remove the bulk of the unwanted plastic - rather more on the trailing edge than the leading edge. I have managed to get a fairly sharp trailing edge as per the original aircraft.

 

 

I added a strip of 30 thou card to the undersides of the leading edges and shaped this and the underside of the wing to give an aerofioil section to the wings. The wing halves were then polished with glass paper and the joints between the laminates filled with Mr Surfacer. This in turn was rubbed down and polished:

 

 

To join the halves I drilled three holes in each half so that I could insert steel pins to reinforce the butt joint. The pins were cut from a paper clip: the wire is rigid enough to make sure that the joint is very strong and will not move when I need to fill it and sand it smooth later.

 

 

I used CA to hold the pins in place and ordinary cement on the plastic surfaces, having first checked that the halves would line up properly when joined! After it had dried out overnight I liberally coated the joint with Mr Surfacer and vigorously sanded it smooth. I cut out the aeileron gaps and sanded these at the same time so that now the wing structure is complete and awaits the addition of the ribs.

 

 

I will add these when the stub wings and elevator surfaces have been made and are ready too.

 

P

[TheBaron]

20 hours ago, pheonix said:

 

I have decided that as showing a photo of the hull coated with talcum powder and dope filler would not cause much excitement

 

Sir. You misjudge us...

 

Those wings; I continue marvel at your patient skill in these matters phoenix.

Bravo!

Tony

[jrlx]

Great work on the wings, pheonix! Very precise, really impressive!

 

I second Tony's remark: you misjudge us regarding the hull coated with talcum powder

 

Cheers

 

Jaime

 

 

[HomerJ_757]

I con, conk, agree with the others, for something as beautiful as the hull that you have created we  enjoy every step on your journey and admire the skill and dedication shown. 

 

Ian

[pheonix]

11 hours ago, TheBaron said:

Sir. You misjudge us...

 

Those wings; I continue marvel at your patient skill in these matters phoenix.

Bravo!

Tony

I hope that I do not misjudge people too much Tony! Thank you for the compliment about my patience: when I look at what you do I can only reply that you do not seem to be too short in that department either!

9 hours ago, jrlx said:

Great work on the wings, pheonix! Very precise, really impressive!

 

I second Tony's remark: you misjudge us regarding the hull coated with talcum powder

 

Cheers

 

Jaime

 

 

Thanks Jamie. The wings took a lot odf scraping (about 4 hours for each half) but I seem to have got there in the end. The filler along the joint is necessary because the edges tend suffer from the sanding and polishing process before they are brought together.

9 hours ago, HomerJ_757 said:

I con, conk, agree with the others, for something as beautiful as the hull that you have created we  enjoy every step on your journey and admire the skill and dedication shown. 

 

Ian

Thanks Ian for the very kind remark about the hull., I greatly appreciate it.

 

P

[pheonix]

Evening All,

 

Readers on another site have asked me to describe in detail the talcum powder and dope method of filling wood grain which I mentioned in an earlier post that I and some other modellers of a certain generation use/have used to fill and seal wood grain. I discovered it in the pages of Airfix Magazine where it was used by the late Alan Hall: I am not sure whether he invented the idea or he picked it up from somebody else, but it was originally suggested for balsa wood. However it works well on basswood too and I have used it on other woods when I have made parts from them. The advantage that it has with balsa is that it provides a hard shiny surface which can be easily painted and takes some knocks without denting easily as balsa can do. It does not crack either, so the paint retains its cover as on plastic surfaces. I am aware that there are other methods to fill wood grain, but this is the one which I prefer.

 

The method is simple but of the bucket chemistry approach.  The ingredients are talcum powder which can be found in any pharmacy or large supermarket, and clear cellulose dope used to stretch tissue paper on flying models:

 

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I put a quantity of dope, (the amount depends on the surface area to be coated), into my mixing container and the puff some talcum powder into it and mix with an old medium sized paintbrush. If the wood is balsa and has a fairly open grain I mix enough talcum powder to make a thick paste - rather like thick glue. This is plastered over the wood and if the wood is joined to plastic overlap the plastic slightly too. The surface will be lumpy: so when it is dry sand it down with medium and then fine glass paper until it is almost smooth.

Now mix a second coat of powder and dope but this time make the mixture thin - like a runny glue. Paint this on to the wood making sure that all of the remaining gaps and hollows are filled. When dry repeat the sanding operation until the surface is smooth.

Finally coat the surface a third time with clear dope only, and when this is dry polish with some of the fine glass paper used previously. This should give you a hard shiny surface which will be indistinguishable from plastic. To clean the brush after each coat I use propriatory cellulose thinners but remember that these are inflammable and should be used in a well ventilated room. They used to reek of pear drops in the past but modern thinners no longer smell so much.

In the case of the hull for this model I only used the thin powder and dope mixture followed by the dope because the grain is so tight that two coats were sufficient to seal it.

 

Just to illustrate what the finished and painted product looks like, (the hull of the current model does not look any different through a camera lens after it had been coated), here is an image of the engine of a Manchester which is made from three pieces of balsa, (main nacelle, upper and lower air intakes) which I converted from the Airfix Lancaster in the mid-1970's in an earlier incarnation as a modeller. The wing outboard of the engine is also made from balsa wood and all have powder/dope grain filler:

 

 

I hope that this satisfies your curiosity. If you have any questions please do not hesitate to ask and I will try to help.

 

Thanks for looking.

 

P

[JOCKNEY]

Brilliant idea, not only will this aircraft look amazing, with the talc it will smell really nice too 

 

Keep up the great work, this is a lesson in scratch building from a master craftsman 

 

cheers Pat

[malpaso]

The dope and talc is also sold ready made in model shops (flying RC type).  http://hurricanemodels.co.uk/engine/shop/product/5527860/Sanding+sealer+60ml?gclid=CjwKCAjw6ZLOBRALEiwAxzyCW_EhlbYjCd-aY7nOudHk1W_Ago_cCqguS9XIdbhWMC-PH3sSh3NxGBoCSlMQAvD_BwE

or cheaper if not for modellers!

https://www.wigleydiy.co.uk/cnp-cellulose-sand-seal-500ml?gclid=CjwKCAjw6ZLOBRALEiwAxzyCWwcTkSvHsx9AjHUDT8E88RXNTUY7j8Ynj80j2iNDMjpnp1v8WbJJsxoClZkQAvD_BwE

The good thing about cellulose is that it can dry , be sanded and another coat in half an hour.  Handy as I did six coats to get a good finish on my P-40 solid, though 2 was enough on my BE-8.

Cheers

Will

Edited September 22, 2017 by malpaso
Examples added

[pheonix]

On 9/22/2017 at 7:03 AM, JOCKNEY said:

Brilliant idea, not only will this aircraft look amazing, with the talc it will smell really nice too 

 

Keep up the great work, this is a lesson in scratch building from a master craftsman 

 

cheers Pat

I am not sure how much the talc will smell when the paint is on... probably more paint than talc. Thanks for the compliment about being a scratch builder.

 

On 9/22/2017 at 7:31 AM, malpaso said:

The dope and talc is also sold ready made in model shops (flying RC type).  http://hurricanemodels.co.uk/engine/shop/product/5527860/Sanding+sealer+60ml?gclid=CjwKCAjw6ZLOBRALEiwAxzyCW_EhlbYjCd-aY7nOudHk1W_Ago_cCqguS9XIdbhWMC-PH3sSh3NxGBoCSlMQAvD_BwE

or cheaper if not for modellers!

https://www.wigleydiy.co.uk/cnp-cellulose-sand-seal-500ml?gclid=CjwKCAjw6ZLOBRALEiwAxzyCWwcTkSvHsx9AjHUDT8E88RXNTUY7j8Ynj80j2iNDMjpnp1v8WbJJsxoClZkQAvD_BwE

The good thing about cellulose is that it can dry , be sanded and another coat in half an hour.  Handy as I did six coats to get a good finish on my P-40 solid, though 2 was enough on my BE-8.

Cheers

Will

Thanks for this Will. As you write, cellulose dope dries very quickly so several coats can be applied in an evening if requires. Sanding the talc-dope mixture does create quite a lot of dust though, but the finish is glass smooth and hard so it is worth it.

 

I have been working on the ailerons. I had cut out the sections from the wings where the ailerons will go, but I need to make new ones as the later versions had balance ears and the outboard trailing edge curved upwards in a similar way to those on the Ago C II. That meant that I had to cut new pieces from 60 thou card with a laminate of 60 thou card:

 

 

 

These look rough at the moment but that is normal for my scratch builds. Once again I decided to use my new tool to make life quicker and easier as there was a lot of plastic to remove:

 

 

By judicious use of the file I was able to remove the underside and introduce the curve on the outer part of the trailing edge. I also thinned the trailing edge and rounded the ear and leading edge. The junction of the two pieces of plastic also needed treatment with Mr Surfacer and the whole units were given a polish with fine worn glass paper. Now they are ready for the ribs to be added which is what the pencil lines are for.

 

 

 

Thanks for looking.

 

P

Edited October 4, 2017 by pheonix

[hendie]

nice work.   I know that shaping is a lot harder than it looks and you've made a great job

[Brandy]

Those look pretty darn good! I'm waiting on delivery of my sihrsc as we speak!

 

Ian

[jrlx]

Great work again!

[TheBaron]

Shapely. Very shapely. That is fine work Mr. P. 

[pheonix]

Thanks Hendie, Ian, Jamie and Tony for the encouraging remarks.

 

I have been working on the part of scratch building WW1 aeroplanes that I enjoy the least - the wing and other flying surface ribs. They are not difficult to put on but shaping and scraping them can get a bit tedious, especially if there are lots of surfaces or if they cover a large area. In this case both apply!

 

The method is simple enough: transfer from the plans the positions of the ribs on to the flying surface with a pencil line. I use Evergreen strip and select a suitable size for respective surfaces. In this case I used 10 x 30 thou for the wing and 10 x 20 thou for the stub wings, and tail surfaces. If the wing ribs sound large just remember the size of the original aircraft - there were lightweight girders in there! The main ribs were added first by applying liquid cement to the wing surface and laying the strip on to it. Liquid cement was then run along the strip to ensure that it was properly held down - these are long strips and the cement dries quickly:

 

 

I added the small leading edge ribs in the same way:

 

 

In the case of these short ribs I had drawn a line span wise along the wing to make sure that they are all of the correct length, in addition to the chord wise lines for each rib. After what seemed like a long half of an evening I had this:

 

 

On to the other flying surfaces and the same procedure was followed. Everything was left to dry overnight. Then I could do what I like doing best with this task which is to trim off the leading and trailing edge pieces of strip. Before I sanded the ribs I added some filler to the edges to help smooth them into the general flying surface. After sanding they are ready for priming:

 

 

Any irregularities which show after priming will be filled with Mr Surfacer and sanded and primed again. These are the ailerons, elevators and horizontal stabilizer for the tail. From the top the ailerons and upper elevator are complete and primed, the lower elevator has still to be filled and sanded and the horizontal stabilizer awaits trimming:

 

 

Still a lot to do on these surfaces before they are ready, so I will plod on....

 

Thanks for looking.

 

P

 

[Brandy]

Tedious but necessary. Coming on nicely though. 

 

Ian

[jrlx]

Impressive precision and patience! Very well done!

 

Cheers

 

Jaime

 

[TheBaron]

Remarkably precise work Phoenix on laying out those ribs. In keeping with your usual high standards of course! 

Tony

[zebra]

Superb, amazing scratch building. Im learning a lot from this group build

[pheonix]

My thanks to Ian, Jamie, Tony and Zebra for your very encouraging remarks. I have to write that I am currently very fed up with repeated sanding, filling and priming of ribs.... only to find still more holes!!! I gave up for a while this week and took a break to make something else, but still took a little time on them which I am pleased to report are now nearly ready....sigh.

 

I forgot to explain how I made the stub wings which are on the lower rear of the hull. They are made from 30 thou card and bent in a pipe of near-boiling water as described by Stevehed. The method is very good for making curved card for wings and other flying surfaces. (I just wish that I could have used the technique for the wings of this model but they were too thick). They were then filed and sanded to aerofoil section in the usual way:

 

 

The stub wings have been given the rib treatment too and are now primed and ready to have the ends drilled to take metal pins: these will be used to attach the stub wings to the hull later.

 

For a change I went back to the hull to drill out the cockpit area. I am not proposing to add internal detail in the manner that Tony has on his Dornier for two good reasons. The first is that I have absolutely no idea of what the internal structure looked like other than the fact that it was built from girders like the wings, and secondly the hull is solid wood and trying to hollow out a section and fill it with detail which would never be seen anyway seems to be going too far, so I have settled for a minimal approach, rather like Airfix and Revell kits of the early 1960's where all you had was a pilot and seat if you were lucky. In my case there will be two seats as the pilots sat side by side. I will put control wheels in too and a generic instrument panel which I think was behind the windshield. Well that is where mine is going!

 

I drilled out the cavity for the cockpit and then lined it with 10 thou card so that it could be painted. I also tidied up around the hole with filler to smooth out the surface:

 

 

The next item was the windshield which sits in front of the pilots. I carved a male mould from balsa and push moulded one from 30 thou card.....and did not think that it looked right. I had been following the drawing but the result looked different from the photos, so I tried again...and again and finally got a shape which I think is close to what the original may have looked like:

 

 

 

It is not glued into place yet because I still have to make the instrument panel and fit that first. While I was moulding the windshield I decided that I would also make a mould for the propellor spinners. This was a piece of 1/4 inch (6mm) dowel with the end shaped to the correct curve. I made 6 spinners to make sure that if I make a mess of one or two (highly likely) I will have enough to complete the job without having to go through the moulding process again. Just to test things I also carved a propellor from some strip wood which I use for the purpose, (please do not ask what the wood is because I have no idea - it was given to me by my late father and he did not know what it is either). The result:

 

 

Only three more to make.

 

One thing that struck me when I was sanding the elevator surfaces was the size of them. On the aircraft they form a biplane structure which was at the extreme rear of the aircraft, and they hinged as a single unit. Just to give an idea of their size I got out my model of the Avro biplane of 1912 which is to the same scale: the span of the elevators is the same as the span of the wings of the biplane! (5 1/2 inches: 14 cm).

 

 

Thanks for looking.

 

P

[jrlx]

More impressive work in display, P! I fully understand that you felt fed up of all the sanding and it was sensible to take a break. I also think your approach to interior detailing makes sense.

 

Looking forward to the next instalment.

 

Cheers

 

Jaime

 

 

[Dazey]

This is very impressive. I'm also learning a lot from this GB.

Regards,

David

[TheBaron]

I see what you mean about the size of those elevators! 

Nice cockpit and propellors. Each little part of this  is a fascination in and of itself.

Tony

[pheonix]

Thanks Jamie, David and Tony for the comments. I have not reported anything recently as I have been away to visit my brother, but we have been busy together as he has helped me with some of the work where two sets of hands were necessary and with a process which I have not mastered - soldering.

 

Before I left to see him though I added two small pieces of 60 thou card to the middle of the hull sides. These represent where the rear cabane struts were fixed to the top of the hull: the hull tapers slightly in plan but the cabanes were parallel with the thrust line and set close to the hull edge at the front.. Consequently the rearmost attachment point was slightly outboard of the edge of the hull and some form of bracket was fixed and then concealed behind a cover. It is not entirely clear from the photos what this looked like so I have shaped the card to what I think is a fair representation:

 

 

 

All of those crosses on the top of the hull mark where I will have to drill locating holes for the cabane and engine support struts. The one in the centre is where the boom will be inserted into the top of the hull. First though the boom had to be made. For reasons of strength I decided to make this from brass rod, using 1/16 inch (1.6mm) for the arm which will be fixed into the hull and the 4 long arms, and 3/64 inch (1.19mm) for the cross pieces. I had intended to superglue these together but after a discussion with my brother he suggested that this would not be strong enough particularly given that the top side booms are attached to a single boom which enters the top of the hull via a triangular piece. This strange design came about as a consequence of the redesign of the engine installation: originally this machine was powered by three engines in the hull connected to the propellors via drive shafts. This arrangement was not very satisfactory for a number of reasons, among them being that one of the drive shafts broke causing the aircraft to make a forced landing. Then when the pilot tried to take off the central unit broke away and severely damaged the tail booms in the process. This caused a major redesign of the aircraft. The hull was reshaped, 4 engines were fitted instead of three, and these were placed in tandem in nacelles between the hull and the wing. This in turn meant that the upper boom attachment had to be reduced to a single central arm to clear the rear propellors.

 

My brother is very skilled with a soldering iron so he offered to make the upper part of the boom with the triangular joining piece and central arm for me. The triangular section was cut from a piece of brass sheet and after the boom parts had been cut form rod and the ends filed and cleaned, they were mounted on a jig of balsa wood to check size and alignment prior to soldering:

 

 

Both ends of the boom are too long. This was done deliberately so that they can be cut to the correct lengths later: in particular the forward end needs to be buried as deeply into the hull as possible to give maximum strength. The boom was soldered and the new piece had the very small amounts of excess solder removed with a file.

 

Then we set about drilling the holes for the booms in the hull. The hull was wrapped in cloth to protect it as it was held in a vice and G clamp to make sure that there was no movement when we started to drill the holes. The first one to be drilled was the most difficult: this was the central hole in the middle of the hull. This has to penetrate at a low angle which meant that a small vertical pilot hole was drilled to a depth of approximately 1/4 inch (0.5cm), and then a paper template which had been made from the plan was crudely taped to the hull just to one side of the it:

 

 

We checked the alignment by pushing the single arm of the boom into place:

 

 

 

No extra drilling needed there! This now formed a convenient alignment jig for the two holes which had to be drilled in the lower rear of the hull where the lower boom arms will be fixed:

 

 

When both holes had been drilled we were able to use the boom to make sure the gap and angle was right:

 

 

 

Now I have to cut the remaining the parts of the boom assembly from brass rod and fit it to the hull with epoxy and superglue. However I will drill all of the remaining holes in the hull and wing first, as the hull will be easier to handle without a large lump of brass sticking out of the rear!

 

Thanks for looking.

 

P