Opperman


 * There are also several persons called Opperman, listed at Opperman (disambiguation)

S.E. Opperman Ltd. was an engineering firm in Elstree, Hertfordshire, England. In 1862, the company was known as Opperman Sons & Taskers Ltd., at which time they were specializing in gear cutting and gearboxes. In 1934, they became S.E. Opperman Ltd. and began also manufacturing aircraft components. During WWII, they were a notable part of the war effort, making a number of components for naval vessels and aircraft. Their first foray into vehicle production came in 1942, in the form of a large, 8-wheeled, amphibious scout car called the Scorpion, which was built in hopes of making a production deal with the Department of Tank Design. Though it did well in testing, the design was ultimately rejected in favor of offerings from other companies, so the Scorpion project was abandoned. One of their most well-known products was the Motocart, which was a Monowheel tractor, introduced in 1946. The Motocart was available with either an 872cc JAP with 8 bhp or a 630cc Douglas with 6 bhp, both being single-cylinder, 4-stroke, petrol engines. The Motocart remained in production until 1958, with a notable number of them being exported. In 1956, Opperman debuted their first road car: the Unicar. This was followed by the introduction of their second car, the Stirling, in 1958 (though the Stirling never went into production).

Unicar
S.E. Opperman was a British engineering company that became known for their ‘Motocart’ 3-wheeled tractors in the 1940s and 1950s. However, seeing the growing popularity of microcars around England in the ‘50s, they decided that they wanted to build their own entry for the segment. They enlisted Lawrie Bond to help design it, who was also responsible for designing the Berkeley micro sports car and the Bond Minicar. The result was the Unicar: a four-wheeled, 4-passenger family saloon, which was rather unusual to see in the world of microcars when it debuted, in 1956.

Early Unicars, designated ‘Model A’, were powered by a 322cc Anzani 2-stroke twin with 15 horsepower, but fairly quickly they changed to a 328cc Excelsior 2-stroke twin with 18 horsepower (both of which were also used in Berkeley cars). These Excelsior-powered cars received a few other minor changes and were referred to as the ‘Model T’. Thanks to the extra power, they now had a top speed of over 60 miles per hour, and they were able to comfortably sustain 50 miles per hour. The easiest way to quickly distinguish the Model A from the Model T externally is the placement of the wiper motor/arm. The Model A had the wiper motor mounted above the windscreen, then it was moved to below the windscreen for the Model T. Earliest examples of the Model A also featured slightly different rear bodywork and tail lights, but this was changed after just a handful of cars were made.

Just like the Berkeleys, the Unicars utilized a fiberglass monocoque construction with aluminum supports, which helps keep the weight down to just 730 pounds. The engine is mounted directly between the tiny rear seats, and power is delivered through a 3-speed (with reverse) sequential Albion gearbox to a solid, chain-driven rear axle, as you might see in a go-kart. Since there was no differential, they made the rear track narrower to allow for a better (but still quite poor) turning circle. The rear axle has just one central damper, and braking was provided by cable-operated 6" Girling drums at each of the 12” wheels. Interestingly, the rear wheels were mounted 'backwards', with the valve stems towards the center of the car.

The lower cushions of the rear seats were hinged, allowing access to a small compartment in the box-like pedestal of each seat. The battery was housed in the right compartment, while the tools were in the left. The petrol valve was controlled with a small lever at the upper left corner of the rear seat back. Since there was no boot, the primary storage area was a huge shelf underneath the dash, which carried a full size spare tire on the right side. There was also a generous amount of open space in front of the footwells, in the nose area of the body. The simple front bench seat could be adjusted fore and aft by tilting it forward and moving the locating pegs into one of several slots in a floor-mounted plate. The doors were exceptionally long, providing great rear seat/engine compartment access, but getting in the front seat was slightly awkward, and operating the interior door handle was even more so, as it was mounted at the very back edge of the door, well into the rear seat area. The doors featured sliding glass windows, which had nice aluminium brackets with 3 distinct stops for the window catch to lock into, giving you 3 lockable postions for the windows: open, half-open, and closed.

When the Unicar was introduced, it was the cheapest 4-wheel car on the market in England and received a good amount of positive press, but even so, sales were slower than they had hoped. In 1959, they began to offer the Unicar as a low-cost build-it-yourself kit (which also avoided the 33% vehicle purchase tax, at the time) in hopes of attracting more buyers. The kit was delivered in 8 large, well-packed wooden crates, and after following their detailed instructions to build the car, Opperman would even provide a free vehicle inspection service before the car went on the road.

While the kit option helped sales, it still wasn’t enough, and Opperman ended production of the Unicar in late-1959. From 1956 to 1959, 306 cars were produced (50 Model A, 256 Model T), and the survival rate is very poor, with only 7 currently known to have survived.

Stirling
In hopes of broadening their market appeal, Opperman built a larger mid-engined coupe with a sporty body, which they debuted at the 1958 Earl's Court Motor Show. Compared to the Unicar, the new 'Stirling' featured things like 4-wheel independent suspension, winding windows, a 4-speed gearbox, a differential (made in-house by Opperman), and 7" hydraulic Girling drum brakes. The added size and refinement compared to the Unicar meant extra weight, with the first car weighing approximately 900 pounds (408 kg). To improve performance, Opperman made a number of modifications to the 328cc Excelsior twin they had been using successfully in the Unicar. The modifications including things like a longer stroke crank (66mm vs. 62mm), larger cylinder bore (64mm vs. 58mm), increased compression (8:1 vs 7.5:1), and a larger carburetor. The results were promising, with the new 424cc unit providing 25 bhp at 5,500 rpm, which was an increase of 7 bhp (~40%) over the standard 328cc units. Opperman claimed that this drivetrain gave the Stirling a top speed of 70+ mph.

Perhaps Opperman foresaw problems with having to build these 424cc motors for use in every Stirling, as the second car built featured an 'off-the-shelf' production engine; a 4-stroke, horizontally-opposed twin-cylinder unit from Austrian manufacturer Steyr-Puch, displacing 493cc and providing approximately 20 horsepower. So a bit less power and a notably heavier engine, but likely a more reliable option for the application, in the long run. This second Stirling was actually built with LHD controls, and it was tested extensively in Austria before being shipped back to England.

Having decided upon using this Steyr-Puch engine for production, Opperman made the plan of building an initial run of 50 cars without drivetrains in their workshop in the UK, and then they would be shipped to Austria to have the drivetrains fitted and tested in the cars. Unfortunately, production of the Stirling kept getting pushed back (some say due to supply issues caused by BMC, who were preparing to release their new Mini), and then later in 1959, Opperman was acquired by E.V. Industrials, who had no interest in continuing the production of automobiles.

With only 2 prototype Stirlings having been built, the project was abandoned, and the first car (with the 424cc Excelsior) was sent to the company dump and destroyed. The second Stirling (with the 493cc Steyr-Puch) returned from Austria a bit later, but as the company had already moved on with other projects, the car flew under the radar and avoided being destroyed. It later got sold off, and it still survives in the UK today.