Model Review

By Staff
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Perkins half-scale model.
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View showing ignition and valve gear, of the Perkins.
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View of operating mechanism, Otto-Langen.

32 South St. Clinton, New York 13323

Recently, I have purchased some models advertised in GEM, namely
the Otto-Langen model by Wayne Grenning and the Perkins model by De
Bolt Machining. I thought you readers might be interested in
reviews of these models.

Perkins Engine: Perkins Windmill Engine
1/5 scale. Maker: De Bolt Machine Type: Hit
& Miss Availability: Castings; machined unfinished; finished.
Air and water cooled versions. No longer in production.

I remember seeing this model for the first time at the Cool
Spring engine show several years ago and I was so impressed that I
knew I had to have one. It is a nice looking model, all decked out
in burgundy and green with brass and bare metal details. It is a
vertical, with a sideshaft with brass governor balls, cast brass
muffler, brass gas tank, plumbing and carb, and a very well done
brass bodied ignitor. I managed to get my hands on an air cooled
version second hand after they went out of production. The engine
is a fair sized model, just right for a nice running model, but a
bit heavy. It came complete with a low tension coil, and factory
skids. All that was needed was a battery and some external
connections. The model I got was originally an unfinished
mechanic’s kit, so I decided (after playing with it) to take it
apart, strip the old finish off, and re-do it.

The castings on the model are of good quality, but a bit rough.
I noticed a few flaws and sand holes, but nothing that affected the
operation or appearance of the model. The machining is excellent,
and all parts are interchangeable with other Perkins models
machined by De Bolt. Everything, including the original style dome
head bolts, was done on CNC equipment, and therefore very accurate.
The model comes with a nice brass tag pre-stamped with a De Bolt
serial number. The model is made from iron and brass castings, and
steel and brass stock.

Assembly instructions came with the model, including photos of
the completed model, and photos of each part, for identification.
The instructions are brief, but not beyond the ability of most
mechanically inclined people. Also included are diagrams for
electrical wiring and timing.

The model itself is a very handsome model, and a fair
reproduction of the original. After examining several pictures of
original engines, I noticed a few differences. The original had a
two-part gas tank with an insert which allowed the operator to
refill the engine without having to lift the filler can up to the
rather lofty gas tank. The model has a tank with an internal syphon
to regulate the flow of the fuel. Because of this, a rather large
and unsealed check ball under the carb is required to prevent the
fuel from syphoning out during idle times. Also, the cooling fins
do not go as far down the cylinder as they do on the original. This
was obviously done to enhance the appearance of the model, since
the original is rather awkward looking.

The model runs fine on a 12 volt motorcycle battery, or two
six-volt dry cells connected in series. The coil is hidden in the
base, and some external posts on the skid connect the battery to
the rest of the engine. The connection to the insulated electrode
of the ignitor is very tight to the rest of the parts on the head
and hard to get at if it comes disconnected. Connection to battery
saver is much easier. The engine will run on either gasoline or
Coleman fuel. I prefer the latter, because it doesn’t smell as

The engine can be a bit cranky, and is prone to the ailments of
all ignitor fired engines, namely low battery voltage and carbon
buildup. The only tricky thing with starting is not to roll the
engine backwards. The cam and ignitor trip are screwed to the top
of the lay shaft, and will unscrew if turned the wrong way, thus
changing the timing. It is quite forgiving, however. Governor
adjustment is also tricky, but I have found that if you set the
collar that holds the spings so that the springs have no effect
whatever, the engine runs very nicely, without the tendency to run
away. Light oil is a must for the governor. All other parts are
oiled with oilers, oil holes and oil cups.

Overall, this is an excellent model. It is great for those who
have small apartments like me, but like the way big engines run. It
looks good, is very interesting to watch and work on, and is an
excellent value, considering the costs of machining these days.

Otto-Langen Engine: Otto-Langen
l/7th scale Maker: Wayne Grenning Type:
Atmospheric Availability: Finished unpainted. Also available in
1/14 scale.

OK, so you don’t like the selection of run-of-the-mill
models these days, and you don’t have the resources to machine
castings or design your own model. Well, this may be the answer.
Here we have a 1/7th (approx.) scale model of
the first commercially successful internal combustion engines, and
one of the most unusual models I have ever seen. It is not a four
cycle engine, or even a two cycle engine, and it is also not a
hot-air or steam engine, either. It is an atmospheric engine. Its
cycle begins when a charge of gas and air is ignited at the bottom
of a cylinder, causing a piston to be pushed upward. A rack on the
piston engages a gear, but no power is transmitted due to the
action of a one-way clutch. The momentum of the piston soon causes
the air pressure in the cylinder to drop below that of the outside
air. The piston is then drawn downward by this pressure change, and
at this time, power is transmitted to the main shaft (hence the
term ‘atmospheric’). When the piston reaches the bottom of
its travel, a system of levers and cams causes another charge to be
introduced into the cylinder, and the cycle repeats.

The engine is available in two flavors; small and big. They are
all preassembled and tested at the factory, then the flywheel and
piston guides are removed for shipping. The entire model, save the
flywheel and pulley, is machined from stock, hence no casting kits.
Because of alignment problems, unassembled kits are not available
either. The model I have is of the larger variety. It is made from
steel and brass stock, with a cast iron flywheel and pulley.

The model is quite well done, and great care was paid to
detailing and cosmetics. It is not very heavy, but the high piston
guides make it a bit unwieldy. It is unpainted, and it is lightly
oiled to prevent rust. It comes with a finished,
polyurethane-coated ply base, wiring connections, alien wrenches,
and extra contact material for the ignition. It also comes with a
spark plug, and care and feeding instructions. The necessary
regulators and coil for running can be provided at extra cost.

The original Otto-Langen has flame ignition incorporated in the
slide valve. For practical reasons, this was replaced with a small
model airplane spark plug, which, along with all connections, is
hidden in the base such that all wiring is invisible. The original
was water cooled and the model is not. I have run mine all day with
the cylinder getting only lukewarm. All other components function
as on the original. The clutch is a good reproduction of the
original, cosmetically, but a modern roller clutch is used for
trouble free operation. The model requires a supply of gaseous
fuel. I use the recommended acetylene. I also use a 6 volt buzz
coil; 12 volt coils tend to wreak havoc with the timing points.

Once a model is set up as per the instructions, it is extremely
easy to start, and stays running. There is no governor (the
originals did not have them), and the speed is controlled by a
valve over the exhaust port. There is no timing to get out of
adjustment. The model is very fascinating to watch run, with all
the cams and levers and ratchets and pawls doing their thing at
intermittent intervals. The only problem with running the engine is
that if you turn the engine backwards with the ignition on, a
greater than normal charge is drawn into the cylinder, and you
could destroy the engine if this is ignited. The operating
instructions need to be followed closely in this regard.

I have observed the smaller example of this engine, and it
appears to be just as easy to operate as the large one, which is
not always the case with the scale down I .C. engines. These are
just as well done as the large engine, but due to the size, it is
not as finely detailed. It sells for the same price as the large

Overall, it is a very nice model, and a real crowd pleaser. If
you can part with the substantial amount of money needed to buy it,
it is definitely a worthy addition to any collection.

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