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X-Craft - Albino Benedetto
Model Data
Model build by Albino Benedetto, Italy
Kit Manufacturer Scratch Build
Scale 1:72
Gruppo Modellistico Sestese
Website of the modeller

X-Craft - Albino Benedetto

Many years ago I saw a movie dealing with valiant British sailors that were engaged in offensive action against German warships using midget submarines.

Unfortunately I can't remember the movie title, the only thing I remember is that the main character was James Caan.

The mini-sub were fascinating pieces of engineering and I wanted to build a model of one of them.

At that time I'd not enough documentation to afford such en enterprise.

Recently I came across a book from Chatham Publishing of London titled "Midget Submarines of the Second World War" – by Paul Kemp – ISBN 1-86176-042-6. This book is part of the "ship shape" series and is very well done and full of both historical and technical information.

In the same book you can find two large scale drawings depicting a British X-Craft on one side and a German Seehund on the other. The drawings are in scale 1:24 and very well done.

The X-Craft

The “X-Crafts” were midget submarines about 15,5 mt in length with a crew of 3 or 4.

The 4th man was a diver to help the sub in overcoming the enemy protective nets and to attach the explosive charges to the hull of the target ship.

These subs were conceived in 1942 with the aim of attaching the German battleship Tirpitz.

The attack was unsuccesful (the Tirpiz was sunk later on by air bombing) but the sub demostrated the validity of the idea and used with success in other different actions.

I'd tried some research on the WEB, but with scarce results.

I was more fortunate when, during a visit to the Imperial War Museum at Duxord (Cambridgeshire), I found an X-Craft (late model) well restored and arranged in such a way that you can walk "trough" and get a glance of the very small interior.

The Duxford's X-Craft is a "late" version produced after the War, but very similar to the early version.

Then I went to Gosport and visited the "Submarine museum". Among other things I found a WW2 X-Craft still under restoration under a temporary shelter (nowadays it is in its final position inside the museum), and having received the proper permission, I got some first hand pictures of the craft.

Technical data of an X-craft of the X 5-10 and X 20-25 series:

Lenght 15,722 m (51' 7")
Beam 1,753 m (5' 9")
Draft (front) 1,60 m (5' 3")
Weigth surfaced 27 tons
Dived 29,8 tons
Side load  4 tons
Explosive charge 4480 lbs
Max. surface speed 6,25 Knots
Max. dived speed 5,75 Knots
Endurance @ 2 Knots 82 nm
Operational diving depth 91,5 mt (300 ft)
IC engine (Diesel) Gardner - 42 HP @ 1800 rpm
Electrical motor Keith Blackman - 30 HP @ 1650 rpm
Battery Exide 20SP 112 celle 440 Amp Hour per 5 Hr

The above mentioned book deals with various types of "small" assault underwater weapons of different nations.

Among them is depicted the italian SLC (Siluro Lenta Corsa – Slow Moving Torpedo) nick named "Maiale" (pig).

The X-Craft is depicted in a long dedicated chapter with drawings and pictures.

The model

My model is made in scale 1:72.

When I decided to build the X-Craft model, I was already aware that there was at least one kit marketed: "Pit Road – Sky Wave" offers a resin kit in scale 1:72. The problems with this kit are that it is almost impossible to find in Italy and the price is too high for my taste.

Everything considered and the subject examined, I decided that a scratch build constrution could be affordable.

Examining the craft splitted in parts I found that it is essentially a cylindric body with conical ends and with a simple open bridge superimposed.

There is a bottom keel (square in section) and the war load in a couple of detachable side appendices.

A single screw is in the center back and a cruciform steering-diving complex is at the extreme back, resembling a small airplane tail.

The X-Craft were built in bloks, basically similar but differing in small particulars.

The bloks X 5-10 and X 20-25 were from the same design

The following drawing (taken from the book) shows the boat. The dotted lines outline the war load.

The Duxford exhibit gives an idea of the actual dimensions of the real thing:

A second picture depicts the Gosport exhibit, this sample was on restoration when my visit took place:

Already in Gosport there is a big scale model (1:24 ?) very well done and detailed:

Construction of the Model

The main body of the hull has been turned from a rod of plexiglass. Only the extermities have been omitted (see the bottom of picture 1).

The side shells separation have been also turned. Since the actual seams were welded therefore leaving a protusion rather than a negative line, the groves have been filled with a copper rod to simulate the welding path.

The upper bridge on the real thing is a free flooding structure. Water and air are free to get in and out. I decided to reproduce this feature (picture 1 in the middle).

In order to obtain a "hollow" piece, still maintainig a sufficient strenght I took advantage of my vaccum forming machine.

First of all I made a "male form - solid" starting from a piece of wood duly carved following the drawing, slightly smaller to take into account the thickness of the plastic to be vacuum formed over (see picture 1 in the middle).

Once the male form is completed, the vaccum forming process is very quick and the end result is a sturdy hollow piece of plastic (see picture 1 on top).

The stern steering and diving palne, along with their fixed parts were thick styrene sheets roughly cut to shape using a jigsaw and finished with small files, then drilled in order to reproduce the small holes for the air and water flow. (pictures 4, 6 and 13).

The propeller has been a different affair.

First of all I'd researched among may "spare pieces", hoping to find one suitable for the scope, but I wasn't fortunate.

So I took the hard way: turned a rod of aluminium leaving a "torus" of the same shape as the one left from a rotating propeller. (the diameter of the torus is 10,5 mm).

After the turning phase, I put the piece of aluminium on a divider device and milled three scarfs obtaining three rough blades. The finishing touch was given by hand (picture 13).

The entire bridge is perforated so to let air or water to get into or out freerly, holes being wery well shown on the drawings.

In the model most of them are drilled using a 0,3 mm drill, other are of didderent diameter up to 0,7 mm.

To get into the hull there are two scuttles. I found a piece of plastic pipe of the correct diameter and made two hatches with turned brass (picture 2, 5 and 8).

The bows are made using a solid block of wood hand sculpted (picture 5 and 7).

To have the two mooring eyes I turned a disk of brass complete with a central raised part on both sides, then I saw the piece in two halves and filed out most of the external part of the disk, to simulate the stiffeners (picture 7).

The two side war loads have a peculiar shape and needed special attention.

The central portion is simple: their are almost semi-circular, the problem being the end pieces.

I starded from the easy side, making the central parts, using a plastic pipe (from an electrical tubing, 16 mm in diameter), (picture 2, 3 and 6).

Then I made a wood "master" and vacuum-formed the four end-pieces, making hand adjusments direcly on the model. Everything have been super-glued in place (picture 3).

The small particulars were made using everything within hand reach and a big portion of ingenuity mixed with a small portion of fantasy.

The colour finishing was suggested by the Gosport model: a weathered blue-steel shade.

The first coloring phase was an uniform grey coat, in order to check for surface defects.

Any defect can be easily discovered and fixed at this stage (picture 8 and 9).

To obtain the final color (semi-gloss) I mixed gloss black with matt blue with a small amount of silver. Everything has been applied with an artist's spray gun (last pictures).

The base is a square piece of plastic with a computer printed paper glued on it (picture 15).

A. Benedetto

Picture 1
Picture 2
Picture 3
Picture 4
Picture 5
Picture 6
Picture 7
Picture 8
Picture 9
Picture 10
Picture 11
Picture 12
Picture 13
Picture 14
Picture 15
Photographs: © Albino Benedetto
This article can also be found in Italian at Gruppo Modellistico Sestese