Wings of Intent: BFW M.18d - Dekno 1/72 resin and 3D-printed parts

(for the completed model go here:

https://wingsofintent.blogspot.com/2023/01/bfw-m18d-dekno-172nd-resin3d.html

The gracile figure of the BFW M.18 follows the refined treatment of design lines carried on from its predecessor, the M.17.

The M.18 is considered one of the first passengers carriers to pay for itself and generate revenue, without the usual help from the government in the form of subsides.

It was produced in several variants, having a variety of power plants and configurations, and some of the subtypes could actually look almost like a different design altogether.

The 18d presented by Dekno could transport six passengers in relative comfort, and was used by several countries. Dekno provides boxings so far for German (Nordbayerische Verkehrsflug) and Swiss (Swissair) machines. I have chosen the latter, as many moons ago I had in Switzerland a fantastic time and was treated royally.

The kit released by Dekno adds to their growing line of beautiful civil planes of the Golden Age. Its newest product shows a nice degree of finesse, as Dekno continues to get better. The boxing has very nice decals by Arctic Decals in Finland, and a great number of parts that are 3D-printed (at high definition, fortunately), plus the usual resin main parts. Everything is separately bagged and the most delicate parts are protected by tabs/ears. Clear resin transparencies complete the package, besides the instructions. The kit arrived without damage as Dekno kit boxes are sturdy, and of course the kit was packed inside a mailing box. The main resin parts showed no distortions.

Images below from the ETHZ image repository:

https://ba.e-pics.ethz.ch/catalog/ETHBIB.Bildarchiv/r/462132

Contents, all nicely bagged:

Transparencies are clear resin casts:

The 3D-printed parts:

Some parts are removed from their supports:

We can see that Dekno's approach to parts casting has greatly improved of late:

The floor has some numbers -to help the modeler- that will be erased:

The finely printed seats had detached in transit, and a couple of legs were broken. They were easily and quickly repaired with a bit of superglue:

The engine shows nice and fine detail. These parts should be inspected to remove leftover pips from the printing process in case they are still attached:

The pedals/control column support assembly:

To the left the control wheel that needs a little touch up of repair:

The divots for the seat locations are further drilled to get a firmer grip, and the numbers are sanded down:

The very nice decals:

Another image from the ETHZ repository:

Pages from Le Document Aéronautique (Gallica repository):

I may replace the wheels with Aeroclub items with a fattier tire. The kit's wheels are OK, but I would like a little more volume:

As I have ulterior motives -see below-, I removed the brand logo from inside the fuselage:

The kit has the luggage door already molded:

So it's removed:

The kit's cabin door (there is nothing wrong with it, I just like to do this shortcut) is replaced by a clear part:

New cargo door to pose open:

A couple of small blemishes are puttied:

The new door with its window masks. It will be painted and then unmasked to pose open (I repeat, the kit's door is absolutely fine, I am just shunning from inserting the kit's clear part):

Bear in mind, as your work, that the blue resin parts are softer than the 3D-printed parts, so regulate your force accordingly while cutting, sanding, etc.

If you look at the photos of "191" posted above in this thread, you will see that there is a little snag. The kit's prop matches the Walter Mars engine (the one the kit provides) but not the Lynx visible in photos. For the Swissair kit's specific engine (Lynx) arrangement -as seen below-, you will need a Hamilton-Standard-like prop, that rotates clockwise looking at it from the front.

Now, all the Hamilton-Standard-like props I have in my spares bin rotate "the wrong way" for the Lynx engine (not provided in the kit), so I will keep looking for one, or shape one myself. No biggie, but good to have noticed.
As many modelers know, it's not just a matter of cutting the blades and posing them the other way, because in that case the blade will end up having wash-in (higher incidence at the tip) instead of the proper wash-out (less incidence at the tip than at the root). The solution is to keep looking in your spares bin, find a prop that rotates the way you need, and repurpose it, if it doesn't have the proper hub, diameter, etc.

Here is the new prop (again, that matches the Lynx, not the Mars engine) under construction, with blades from a spare prop and metal tube:

191 is seen in the photos posted above, as mentioned, with an Armstrong Siddeley Lynx engine, not the Walter Mars (which the M.18d also used) that comes with the kit. Did 191 used at some point a Mars? perhaps, it would be nice to see a photo of it, and that engine -again, as already mentioned- does go with the kit's prop.

Another page from Le Document Aéronautique describing the alternate power-plants:

I really like the way the more fragile parts are protected:

Some modelers leave the parts attached until they need them. I like to remove and clean every part before starting assembly, but then you have to be careful not to lose them or brake them. The longer 3D-printing leftover rods can be used to repair for example the seat legs, in case you broke one:

The smaller parts are very well formed and fortunately not fragile (within limits, of course)

They are kept separately:

The interior structure is assembled to see how it fits:

The instructions are not particularly clear regarding where to insert the bulkheads, exactly. This is how I think it would work better::

Fortunately with only a few passes of the sanding stick all goes well (dry run):

Another bulkhead is added to close the luggage compartment, which I had opened to add interest:

Time to deal with the window adjustments. I usually replace any kit flat transparencies with home-made items, cut from acrylic and then individually adjusted to each frame. This way I get most of the times a bit more clarity, but of course you can use the kit clear parts:

Making the window panes individually and adjusting them takes of course time, so this should be done slowly and carefully, knowing that it's somewhat lengthy task:

Preparing for some priming and painting:

And luggage for its compartment:

Some base colors applied:

The seats are prepared for painting. First color will be for the metal tubing and once removed from the holding tape the upholstery will be painted. More pieces of luggage are scratched and a trolley readied for it:

For those interested in using the very beautiful Walter Mars engine that comes with the kit, you have some interesting options. At least two German planes used the Walter Mars too (images from the Net, hopefully not stepping on someone's toes):

Working on the interior:

As a curiosity, there is a version of this plane on floats, but it has a different rudder and was powered by a Wright engine.

Dujin released long time ago resin kits in 1/72nd of several versions of the M.18. Needless to say the Dekno kit is far superior in every single aspect.

The interior is completed. The instrument panel is given its decal. The decals, excellent by the way, are of the continuous carrier type, so you have to cut each subject and then trim the carrier close to the image. They are thin and handle well:

Getting ready for the final push:

The transparencies are in:

The location o the Pitot tube is marked as a dimple. It's drilled for a more tight fit:

Before closing the fuselage, a little trick to save time. Masking the door from the inside will facilitate painting (you won't have to fill the opening with moist paper towel, for example), and then you just carefully pinch it out once done with the painting:

Fuselage closed. The halves match each other very well:

To deal with the seams created be the gluing of the fuselage halves, all transparencies and openings are roughly covered until all puttying, sanding and cleaning is done, then the actual window and windshield masks will be applied before painting:

The horizontal and vertical stabilizers are a very good fit (I metal-pinned the fin for added safety):

The wing roots, which have a locating tongue, are not a good fit, and even after trying to tweak this and that, it's obvious that the way would be gluing them, and then try to work out with filler and the sanding stick. Be also careful of the dihedral angle, as the locating devices don't guarantee it.

The wings are on, and even with the tweaking the surfaces don't match properly and gaps need filling. In retrospect, what I should have done (and what I recommend if your wing roots don't fit well and you have some experience) is to remove the tongue and sand the root flat to match the fuselage, and insert via a rod:

On another note, see how elegant the design is with its high-aspect ratio wings and stab.

A primer coat to all the structure, door and hatch; oil cooler painted:

Little blemishes continue to be spotted and corrected here and there. Two small inspection hatches on the aft fuselage top that were erased during the treatment of the seam, are restored in the form of very thin styrene sheet parts:

Two handles seen in photos are added before painting from a P.E. set:

Looking at photos it's evident that the wing tips and the tail group tips are painted in a color other than the Swiss red. A secret council of modelers was held and it was determined that the most likely color was a medium blue, because of the Bayern connection of the plane manufacturer. Thus the first color that goes on is blue, to be masked as painting proceeds. Other parts -depending on the timeline of the plane represented- may also be painted blue later on:

The Lynx engine arrived. I bought two. They are very good, with very nice detail, and molded in one piece. The drawback: the pushrods are super-thin (to scale) and tremendously fragile. One engine arrived with a couple already broken. I broke more of the second engine while separating it from its casting block, as the casting engineering is not particularly friendly and the resin is super-hard:

I replaced the broken pushrods easily with very fine wire. Now, here is the deal, as explained before, to represent CH-191 you need the Lynx engine, which has seven cylinders, whilst the Walter has nine, thus the kit's nose will have to be modified a bit to accept it. You have two options: do a 7 cyl scalloping replacing the one in the kits nose and shield, or the scalloping will have to go, and perhaps a different insert installed, we'll see:

Here is CH-191 nose (in this photo with no shield of tight scalloping fairing) with the Lynx clearly showing:

If you go this way, you have to either match the wooden prop (I carved this one just in case).

or use a "metal" one as in this photo (from the ETHZ repository as noted on caption):

(with the shield and scalloping you have to use a metal prop):

The scallops are sanded off from the kit's nose part, and a blanking lid is fashioned from styrene sheet, contoured to match the nose:

On this the engine will seat, and there is enough space between engine and "firewall" to add the exhaust collector ring later on.

And so the engine issue is quickly and easily solved:

You can use soft solder, rolled over with a tool to make the collector:

It will go more or less like this:

You can adjust as needed (dry run here). Once the assembly is done, then the little exhaust connectors (one for each cylinder) can also be made with thin solder: