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Monday, December 7, 2015

Scratchbuilt 1/72nd Mercedes Daimler L.21

(this is the step-by-step building post. For the completed model please go here:

The Mercedes-Daimler L.21  was the winner of the Light Plane Class of the 1925 Rundflug.
The L.21 was a parasol plane for one person equipped with two two-cylinder Mercedes engines of 19hp each located on small gondolas on the wing leading edge.
The design, if appealing, is nevertheless a tad odd, with a mix of refinement and some bluntness to it.
I have been gathering material on it for a few years, but the call that brought the model to light came from friend and fellow modeler Sönke Schulz, who is involved in building one, but at the heretic scale of 1/48th.
For such little model, it has a great number of details, and it is a veritable strut forest. Besides the four main wing struts, there are small eight of them to hold the landing gear, four very little ones to steady the engine gondolas, plus eight more for the cabane (that's for you illiterate the structure that unites the wing to the fuselage). 24 in total, for such visit card-size model.
Small does not automatically translate into easy, as you will be able to see in this build.

Laminated wood planks to recreate the original props' effect:
Carving starts:

The usual one-two with the flying surfaces:
Closing them:
Things looking good so far:
Fuselage progresses:
Cockpit details:
Another fuselage is started, the first did not work properly:

Now things are better:
I had to carve very subtle scallops on the center section trailing edge, otherwise my dear friend Sönke wouldn't have been able to sleep:
 The nose is completed with Milliput:
 The engine gondola wood blanks:
 Vacs pulled from the wood masters:
The components are separated from the backing sheet. There are two sets, just in case:
The fuselage has particular shape bellow the nose, this is also replicated:
 Wunderschnitzel! what's going on! they are multiplying:

Some trials are performed in order to find out the best construction method for the wing. In this case a center section and joined outer panels are built:
 The center section is capped (there is a joint in the original and this method will portray it):
 Once those caps are dry, they will be contoured to follow the wing airfoil, and the outer panel will be glued controlling the dihedral -flat on top of the wing and dihedral at the bottom actually:
 Wing panels are assembled:
Props are completed:
The upper part of the engine gondola cowlings had a "blister" to allow for the height of the engine's magneto and distributor, so a corresponding part had to be fabricated:
Sometimes progress seems slow, even if you work on the models:
One of the model "kits" is chosen for completion. A metal tailskid is added to the fuselage. Drilling of locating holes for struts, control cables, cabane, landing gear, etc., commences: 22 holes on the fuselage, 7 holes on the landing gear fairing, 15 holes under the wing:
Metal control horns are inserted in the tail surfaces:
 and in the ailerons:
The stab is separated in halves and the tail group is glued to the fuselage.
The lower halves of the engine pods are attached to the wing:
The upper part of the engine pods is glued in place:
 Faired fuel caps and engine distributor/magneto blisters are glued in place:
A view of the components. I am using Fred Hultberg's FOTOCUT prop bosses:
 The hand carved laminated wood props will surely benefit from this detail:

The door is engraved, and a small slot that is the outing of the throttle control is carved:
 The holes for the cylinders, the prop axle and two struts are drilled on the engine pods. In the background the painted seat and control column (the rudder pedals are already installed):
Instrument panel made of decals and Fotocut bezels:
The landing gear structure in place (minus a couple more elements that will be added later):
 The cabane structure elements, again with a couple missing elements to be added later on:
 Trial of the wing on:
 All seems to work:

 Trial of the landing gear horizontal element on the structure, again ok:
 Paint is airbrushed on the different components with the corresponding colors:
Matías Hagen provided the cylinders (thanks, Matías!):
The parts were masked and secondary colors airbrushed on. The masks removed revealed a so far good finish:
The sub-assemblies and the very nice Arctic Decals commissioned sheet:

Control cables are being installed:
 Already trimmed. Comparison shows a Szybowiec Bydgoszczanka model in progress:
 Control cables for the ailerons and linkages on the wing tips are installed:
 More little struts here and there:
 The wing is glued in position:
 More struts (of course!) ensue, landing gear in place:
 I am preparing a fueling trolley (CMK) that, to be honest, is a kit that leaves a lot to be desired, with great detail and poor engineering. The wheels come flattened against the resin pouring block, so when you cut them away that side has no detail. You are better off replacing the handles and such provided, which are very to scale, but very weak in resin. I don't consider myself a clumsy modeler, and have dealt with resin many times before, but all these little parts shattered when trying to remove them from their casting blocks. I provided a new gas nozzle, handles and wheel axles. The instructions are not very clear in a couple points:
The components are painted before assembly.  This is originally a German 1916/18 pump, so I "re-purposed" it changing the colors to be posed close to the model:

Yet...more struts and wheels now in place:
 A view of the belly of the beast (24 struts total):
 Engine cylinders in place:
 Decals from Mika Jernfors (Arctic Decals) in place. As mentioned before, they are superb:
Almost all elements in place, now fabricating the Pitot/Venturi probe: