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pheonix

1/72 scratch build Hansa Brandenburg W 13

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Evening All

 

I have just completed my Caproni Ca 5 scratchbuild in time to start this GB with a build which I have had on my list, (the scratch builder's equivalent of a stash), for a long time. The reason for the delay is the peculiar shape of the underside of the forward hull: on some early flying boats it was almost flat, (Hansa Brandenburg CC - I will post some pictures of this model in the RFI section shortly), in most it was shaped like a conventional boat hull, but in the case of the H-B W13 there was a double upwards curve. Modelling this will provide the biggest challenge for what will I hope be an otherwise straightforward build. It will certainly be simpler than my last GB effort - the Zeppelin Dornier Rs II!

 

Following the protocols of the GB here is my kit:

 

48630858072_0d6c2d80ee_c.jpg

 

There are some materials missing: some wood for the propellor, and some plastic rod of various diameters. It may also be that I find that I need some other materials as I go along - I will give details later should that be the case.

 

Here are my instructions which also give a useful picture of the type for those who have never heard of it, or have done so but cannot remember what one looked like:

 

48630355078_07fee6a640_c.jpg

 

I am not sure of the number of parts that will need to be made - I will find that out as I go along.

 

Thanks for looking and I am now off to try to work out how I am going to make that double curved hull.....

 

P

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Oh my word, I've been frightened off building Joy / libra models vacforms of simular aircraft, and you are going to scratch build one !

i can't wait 😊 

 

cheers Pat

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Thank you gentlemen for the encouraging remarks - I will do my best to produce a reasonable model.

 

Just as an example of a previous effort to produce a 1/72 scale model from the Hansa-Brandenburg workshop, I scratch built this one several years ago. There is a build thread at https://forum.ww1aircraftmodels.com/index.php?topic=7308.msg134898#msg134898  I have also posted more pictures and details of this type in the RFI section.

 

36184378241_189c092f37_k.jpg

 

The W13 is considerably larger than this but I do not expect that it will take very much longer to build.

 

Thanks for looking.

 

P

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Posted (edited)
13 hours ago, pheonix said:

I scratch built this one several years ago.

.. an excellent precedent! Congratulations, quite an achievement .. but no wonder you gave yourself a break of several years before going again!

Edited by greggles.w

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On 8/28/2019 at 4:44 AM, Thom216 said:

Ah, model kits by Evergreen... Should be something to see!

Yes Thom they are a bit like Meccano -you can build almost anything you want to! The number of parts varies according to how many you choose to make, but there are never short shots, just wrong shaped lumps that have to be made again! Sometimes you have to find additional materials, (wood, metal, etc.), and aftermarket parts are also useful. They never provide transfers so you either have to make your own or raid the spares box. They are also not very good with instruction sheets - they are a bit basic in my experience and you have to work out the construction sequence, but with practice that becomes easier. They also require considerable research, especially if the subject is a bit obscure, but the net has made life so much easier in that respect and fellow modellers are also very helpful. Skill level varies depending upon how many you have made before and whether you have previous experience converting or super-detailing other kits. The main advantages is that they are cheap and are often not available from injection, vacuform, resin or other short run kits. 

 

Why don't you give one a try? They are not nearly as difficult as many modellers think.

 

P

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Evening All,

 

Following Jamie's invitation earlier today I have made a small start: I have cut out the hull sides and rear top and lower surfaces. I have also cut some bulkheads to help make up the square section of the hull - the cross section drawings in the DF are very helpful in this respect: the letters refer to fixed points on the hull where they will be located. All of this was from 30 thou card:

 

48655607152_f3342c4762_c.jpg

 

In addition I have cut out the wing blanks and sanded them to aerofoil section - also from 30 thou card which on this occasion had been bent in a pipe with boiling water. The top wing has three sections as the outer panels were swept back and it was not possible therefore to cut the wing in a single sheet. This will be butt joined later. The lower wings and horizontal tail unit are also cut and shaped - I have still to make a rudder. These are now ready to have the ribs added via 10 x 20 thou strip:

 

48655443166_ac36dcc0b9_c.jpg

 

Thanks for looking.

 

P

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Hi pheonix!

 

Welcome to the GB! Your entry to the first edition of the GB was an impressive achievement, so I'm looking forward to seeing your new scratchbuild project taking shape :thumbsup:

 

Good luck!

 

Jaime

 

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17 hours ago, pheonix said:

Yes Thom they are a bit like Meccano -snip...

 

Why don't you give one a try? They are not nearly as difficult as many modellers think.

 

P

Oh I love Evergreen! Never built a full model from scratch though. Use it plenty to add to kits!

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Evening All,

 

Thanks Thom, Jamie and Greg for the kind and encouraging remarks.

 

I have focussed on the fuselage this week as I wanted to try to solve problem of the double concave curve on the underside of the hull. I had been thinking about it on and off for a time and eventually came up with a simple answer as I hope to show here. First though I had to make the hull - a simple procedure whereby the bulkheads were glued to the bottom of the hull and allowed to set. While that was happening I glued strips along the edges of the hull sides so that when I come to cement the top and bottom faces later they have something to keep them square and even:

 

48694726688_77ed551875_c.jpg

 

Making up the rear section of the hull was a straightforward case of gluing each side to the bottom face and finishing by gluing the top face in place. The assembly was held firmly by state of the art clamps while the glue set:

 

48695068031_064b28f174_c.jpg

 

Note that the nose section was not glued yet - making the hull in stages like this is easier and means that the final result is square and even. Only after the rear end was fully set, (after 12 hours), were the front bulkheads added in the nose section and the nose joined - a small piece of rod helped to reinforce the narrow tip of the bow joint:

 

48695240842_6c11bd80f6_c.jpg

 

There were now two holes at the front: one above and one below. The one below was tackled first as it is this that has the double concave curve in it. I started by cutting a piece of 60 thou card shaped to fit the hole and then used a pair of tweezers to bend it to fit the curvature of the lower hull towards the nose. That was done by gently bending the plastic repeatedly, working backwards and forwards along the curve with two gentle twists of the tweezers at the front for every one towards the rear:

 

48695240797_bf06ac636a_c.jpg

 

It does not matter if the curve of the bottom is not quite precise as it will be pushed into the hole and held by the plastic strips thoughtfully attached to the hull sides as described above: the bulkheads add extra support and also help prevent the bottom plate from being pushed too far into the hole. To make sure that I do not file/sand right through the plastic, I glued a short section of 30 thou card at the rear of the new hull bottom prior to cementing the new hull bottom:

 

48695068331_16d85db866_c.jpg

 

48694726403_d2accc5260_c.jpg

 

The next step was to mark the centre line of the new hull bottom, two perpendicular transverse lines, and fill the side gaps with filler. The transverse lines mark the point where the concave curvature ceases at the front, and a marker for a small jig which I had made from card to test the depths of the curve to keep them even. Now the filing/sanding could begin. I started by using a larger diameter round file to make a shallow groove just forward of the hull step. This could then be slowly and steadily enlarged with fine grade glass paper wrapped around a piece of dowel. By putting slightly more pressure on the rear and by keeping the glasspaper and dowel almost parallel with the hull top I was able to gradually scoop out the required curve under the left side of the hull base. The centre line was used as a guide to prevent me making the curve too wide. The process was repeated for the right side:

 

48695240632_9bc56dcda0_c.jpg

 

48694726288_f0f858ef2a_c.jpg

 

48695067971_e97058321a_c.jpg

 

What I thought was going to be difficult turned out to be relatively easy: there must therefore be hidden problems waiting for me further into this build....

 

If you have been, thanks for looking.

 

P

 

 

Edited by pheonix

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Problem .. solved! Nicely crafted.

 

From what (little) I understand about the undersides of floats / hulls, I gather it’s something of a dark art, particularly getting ‘unstuck’ from the water surface on takeoff.  Just speculating, but I wonder if that double-concave shape might have been less than helpful ...

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Excellent achievement, pheonix! I'm always amazed by your scratch building abilities. :clap2:

 

Looking forward to the next steps!

 

Jaime

 

 

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Sometimes the best tackle to a complex problem is an easy fix.  I have never seen the bottom of this type of plane, but I think what you've done looks real good.

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Evening All,

 

Many thanks Greggles, Jamie. Thom and Stuart for the kind comments.

 

Greggles: yes the art of getting a fling boat/float plane to unstick from water is indeed a dark art and is one reason why in an earlier GB I chose the Dornier Rs II rather than the Rs III. If you look closely at the underside of the hull of the Rs III you will see that it had numerous small steps which would be a nightmare to model. Apparently they were intended to act like steps to help reduce the drag/friction of the water on the underside of the hull. It seems that the idea did not work as Claude Dornier and other flying boat designers reverted to single steps in the hull/floats of later designs. The double concave curve on the underside of the hull was also used on some Lohner flying boats which slightly pre-dated the H-B 13, although the idea did not last so it was probably not a great success. However at this stage of design experience aeronautical teams were clearly still in an early stage of learning about and gaining an and understanding of these complex problems.

 

P

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Evening All,

 

This has been a week in which I too have been learning some dark arts - in my case the use of an electric drill, (ie a Dremmel) on laminated plastic. I decided not to try to mould the upper decking of the hull as this would have meant carving a mould from basswood and then trying to push mould a piece which would sit exactly on the curved upper hull sides. I could see clearly that much frustration and wasted plastic lay on that route so I opted instead to do what I had done on the H-B CC and make the upper decking from laminated plastic. I made one piece which would sit comfortably over the gap in the upper hull:

 

48738590266_2476a9c943_c.jpg

 

A centre line had been drawn on the top of the new hull piece to help me to sand the correct curvature in the nose area and to make sure that the piece was properly centered on the hull. However I did not measure the thickness of the top correctly, and despite adding what I thought was adequate extra card to correct the problem I found that I still did not have enough depth and to avoid unsightly joins on the finished upper decking I decided to scrap the piece and start again.

 

This time I got the thicknesses right so I went ahead and scribed with a pair of dividers where the gunner's cockpit would be and traced and scribed the outline of the pilot and navigator's cockpit. However when I tried to drill out the gunner's cockpit  I found that the Dremmel was so fast, (even on the slowest revs), that it melted the plastic and tore a larger hole than what I wanted! Time to make a third decking piece!

 

Number three was more successful: I was able to get the correct thickness and to drill holes ready to remove the plastic from the cockpit openings without gouging out an excessively large hole. I did this by drilling one hole at a time and stopping the drill to allow the bit to cool between each drilling individual holes. I also cleaned off any plastic which had stuck to the bit and made sure that the holes were not to close to the scribed edge of the cockpits. Here are the two efforts with the failed second attempt on the left:

 

48738265373_eeefe9113c_c.jpg

 

The holes were joined with a scalpel blade so that the centre pieces of plastic fell out and the the final shaping of the cockpit openings was completed with a round and half-round file. A long and somewhat laborious process but as I learned the hard way, one which cannot be rushed.

 

48738265323_9fc9908e0a_c.jpg

 

With the cockpit openings complete I added some basic cockpit details - seats, a control wheel, a panel between the pilot and navigator seats and a seat for the gunner. Very little of this will be visible on the completed model and I do not belong to the school of modelling which insists on adding details which will be forever hidden once the model is complete. I am happy to know that those details are missing and wish to spend more time on getting an accurate outline and detail which can be seen! I also filed the upper decking to the shape of the side profile prior to fixing it in place as this required some hard scraping which would have risked causing damage to the hull if I had glued it in place beforehand. In doing this I got a little carried away and took too much from the top of the rear deck and had to build this area up with filler - hence the large grey area in the image below. I also removed much of the excess plastic on the sides of the decking at this stage again to reduce the risk of damage to the hull sides.

 

48738590051_e4dbd3275d_c.jpg

 

The upper decking was glued to the hull and held in place overnight with the same state-of-the-art sophisticated equipment as was employed earlier to hold the hull bottom in place and described above. The centre line on the decking enabled me to get the accurate positioning for the cockpits relative to the rest of the hull. From the left (port) side the hull now looked like this:

 

48738589976_6d41330d62_c.jpg

 

Final shaping could now begin. First the sides of the upper decking were filed so that they were flush with the rest of hull sides and then the curved nose section in front of the pilot's cockpit was sanded to shape: I used a card template made from a cross-section diagram on the plans to achieve as close a match to the profile as I was able. The centre line and a cross line can be seen on theses images: the latter marked where the template was used to check the cross profile. You van also see the filler that I had to add to the hull sides below the decking to remove a small step caused by the thin plastic bending inwards when it should really have curved slightly outwards. I am hoping that none of this will show when the hull is painted and the wings are in place....

 

48738265208_fbcd4b41fe_c.jpg

 

48738265063_be33277b2b_c.jpg

 

Having got the decking as I thought that I wanted it I checked the lower wigs against the sides of the upper decking - and found that in spite of the filler the shape was still not right....! So out with the file and remove the front end of the filler to the plastic below and glue into place a piece of 20 thou card. A file and glass paper were brought into action when the plastic was firm and the edges of the new piece of card concealed with yet more filler....

 

48738827237_8ce7073117_c.jpg

 

Now the wings fit without an unsightly gap. Still the hull is not complete however. I have made a fin from 60 thou card with two pieces of 20 thou card at the base. The fin of this machine was very wide at the base and tapered upwards so I had yet more filing, sanding and filling to do before it was finished:

 

48738772352_2420548496_c.jpg

 

48738318963_c087661f97_c.jpg

 

Now I can add the gunwale along the sides of the nose and bomb rack strips to the front section of the upper hull, but more of that in a later post. 

 

Thanks for looking.

 

P

Edited by pheonix

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Impressive work! Beautifully shaped hull/fuselage.

 

Cheers

 

Jaime

 

 

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Good progress.  I did a little laminating for my Crusader wings, with variable results.  I think my error was supposing I needed the thinnest possible cement, which I now suspect did not sufficiently ‘weld’ the layers into one.  I haven’t had a need to repeat yet, but I did think I might use a more ‘corrosive’ cement, or maybe pre-sand the faces to key better .. or?? Do you do any particular prep? & which glue do you use?

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Great work Mr P.

48738590051_e4dbd3275d_c.jpg

Purely an observation but is the cockpit shape a bit out or is it my eyes?

 

Stuart

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13 hours ago, greggles.w said:

Good progress.  I did a little laminating for my Crusader wings, with variable results.  I think my error was supposing I needed the thinnest possible cement, which I now suspect did not sufficiently ‘weld’ the layers into one.  I haven’t had a need to repeat yet, but I did think I might use a more ‘corrosive’ cement, or maybe pre-sand the faces to key better .. or?? Do you do any particular prep? & which glue do you use?

I have used laminated card many times now, for wings, floats and in this case fuselage decking. I use the thickest card that I can and if I have to insert thinner card I try to sandwich the thin sheet between thicker units. I have tried sanding to roughen surfaces but I have started to use old fashioned thick cement from a tube rather than the newer thin varieties. I apply a liberal coat of cement to one surface and then firmly clamp the plastic,(or put the laminate under some heavy books), and leave for 12 hours. This method is not infallible as sometimes very thin edges can lift but I get over that by applying Mr Surfacer which generally solves the problem. In the case of the hull decking on this model the joint has held very well and needed no extra filler.

 

P

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