The Fenian Ram

By Staff
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View of the crank throws. Note there are two to drive the crosshead from the outside.
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The Fenian Ram, as it’s called, is equipped with a Brayton cycle engine and is on display at the Paterson Museum in Paterson, N.J.
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Front end of the Brayton showing the main parts of the power cylinder. The valves are actuated by a cam driven by a toothed chain on the far side.
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The Brayton actually air starts itself once the igniters are inserted into the ports and air is released into the cylinder.
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View looking back from the front wall of the crew compartment. To get out of the sub, you have to crawl on top of the bevel gears that drive the propeller.
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View of the sub’s interior showing the Brayton engine cylinders on the starboard side. The hatch is located just above the large bevel gear at top right of photo.

In 1999 I had the chance to visit the Paterson
Museum in Paterson, N.J. It was a dreary, rainy weekday and I was
passing through on my way to attend a conference at Stevens Tech in
Hoboken. At this time I had been into the engine hobby about seven
years.

As I toured the museum, I went to look at the “Fenian Ram,”
secretary of the Navy John Holland’s submarine. The placard said it
was powered by a Brayton cycle engine. Now my interest was piqued
and I approached the curator, Bruce Balistrieri, and told him about
my hobby and my interest in such an unusual engine. He asked me if
I would like to climb inside and see it for myself … I was in
there for the better part of an hour.

The Fenian Ram

The Fenian Ram was designed by John Holland and launched in
1881. Upon first seeing his design, Holland proclaimed it as “a
fantastic scheme of a civilian landsman.” Holland’s brother,
Michael, had been introduced to the Fenian Movement, who sought
Irish independence from British rule and had organized a
skirmishing fund. The purpose of the fund was to build a three-man
submarine to use against the British Navy. Work on Holland’s boat
started in May of 1879 at the Delamater Iron Works in Manhattan,
N.Y., and was launched into the Hudson River two years later. The
Ram’s hull was 31 feet long and roughly 6 feet in diameter, with a
shallow conning turret on top. Armed with a coaxial pneumatic
“dynamite gun” in the bow, the 19-ton boat was intended to support
a crew of three: a commander, an engineer and a gunner. The Ram was
capable of nine knots, depths of 50 feet and stayed down for as
long as an hour during tests, which took up to two years to
complete. The Fenians, frustrated with Holland’s delays and faced
with internal legal squabbles, stole their own boat and hid it in a
shed in New Haven, Conn., where it remained for 35 years. Holland
had nothing more to do with the Fenians, and the boat was
eventually donated to the city of Paterson, where it sits now.

A Unique Brayton

The Brayton cycle engine differs from the familiar Otto cycle in
that instead of compressing the air/fuel charge and then igniting
it, the Brayton cycle injects a compressed air/fuel charge into a
cylinder where it is ignited and continues to be injected and
burned for roughly half of the power stroke. After the air/fuel
injection ceases, the remaining hot gases in the cylinder are
allowed to expand until the bottom of the stroke is reached. Then
an exhaust valve opens and the spent mixture is forced out of the
cylinder. The Brayton cycle is referred to in engineering lingo as
a complete-expansion diesel cycle, or Joule cycle. A modern jet
engine is also called a Brayton cycle, but instead of pushing a
piston, the compressed fuel/air mixture is burned and allowed to
turn a turbine.

The Brayton engine in the Ram is a unique design. It has two
tandem cylinders driven from both sides on the outside of a
crosshead between them. The crankshaft has two throws in the same
position. The front power cylinder operates off of compressed air
generated by the rear cylinder, and a receiver stores the excess
compressed air. Fuel is metered in the intake ports by small
injection pumps. These pumps were crude by today’s standards,
employing a plunger and slide valve to direct the fuel to the
cylinder. The valve mechanism, fuel pump and governor appear to be
driven off of a toothed chain. On the top ends of the power
cylinder are openings that I believe are for inserting either a
preheated platinum sponge or a burning wick. In operation, the
igniters are inserted in these ports and the air is turned on. The
Brayton literally air started itself.

John Holland was clever in using a Brayton engine in his
submarines, as the excess compressed air was probably pumped into
large tanks in the front and rear of the submarine for blowing
ballast and possibly operating the engine. I do not know whether
the sub ran powered while underwater using the stored compressed
air. If it did, I am sure it would not have traveled far since the
pumping cylinders were capable of pumping the air tanks to 80-100
psi. The trail of bubbles from the sub operating under power would
have been a dead giveaway as to its position.

All the literature I’ve seen on the Brayton has shown the
pumping cylinders to be about 50 percent of the power cylinder
volume to maintain adequate air volume for running the engine. Lyle
Cummins’ book, Internal Fire, has an excellent chapter on this
unique engine.

Brayton’s first engines compressed a mix of gas and air in a
receiver where it was then metered into the cylinder. A screen
plate between the compressed gas supply and near the intake valve
prevented the compressed gas mixture from exploding in the
receiver. Still, explosions in the receiver did occur, popping a
safety valve much to the discomfort of the operator.

Later Brayton engine designs utilized oil vaporization at the
intake valve area by a wick arrangement. As the air rushed by on
the admission period, atomized oil was carried through the screen
or grating into the cylinder.

The grating in the intake valve area was a key element for
keeping the combustion products within the cylinder. The Brayton
always operated with less pressure in the power cylinder than the
compressed air supply. Additional volume of gases to produce useful
work was generated by burning fuel in the cylinder.

Since Then …

Most of the illustrations in Cummins’ book show a sideshaft
driving the governor, valves and fuel pumps. Perhaps space
constraints in the Fenian Ram necessitated using a chain-like
affair to drive them. As you can see in the photos, space was
limited inside the Ram. I had to crawl down on top of the large
bevel gear that drove the propeller to get inside. No doubt being
aboard this submarine while under power would have been a scary
experience given the spinning flywheel, gears and reciprocating
crosshead flailing away. It makes you wonder what a quick tip or
bump could have done to one of the crew members.

I took these pictures in late April of 2005. Since my first
experience inside the Ram, the museum staff appears to have cleaned
up much of the inside, and the engine appears to be in a very
stable state of preservation. While much of the engine appears to
be frozen with rust, it could probably be freed up with little
effort. Still, the Fenian Ram offers a wonderful opportunity to
view one of the truly unique inventions in the history of internal
combustion development.

If anyone is interested in this unique type of engine I’d be
glad to try to answer any questions you may have. One of my
back-burner projects is to convert a 2-cylinder opposed-piston
compressor to a Brayton cycle oil engine.

The Paterson Museum is located in the Great Falls Historical
District just off of Interstate 80 in Paterson, N.J. They can be
contacted at: Thomas Rogers Building, 2 Market St., Paterson, NJ
07501; (973) 321-1260.

Contact engine enthusiast Paul Gray at: 3437 Blue Ball Road,
North East, MD 21901; 302-598-5113; pcgray@zoominternet.net

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