Germany - Lightweight RV Leaders
"The English-American caravans are certainly extremely comfortable, but they are heavy, unbelievably heavy. The people there have large tow vehicles and the money to tow these petrol-hungry machines. In Germany we have neither the money nor time to meander slowly from one luxury resort to another. We must work, we have light cars and little time. We only have the weekends and a few days or weeks at the height of summer."
Hans Berger, 1938
Germany in the 1930s was not the ideal time and place for leisure innovation. But during this decade a small number of German RV designers managed to come up with some pioneering designs that led the way internationally in lightweight RV design.
Out of Necessity
Germany's post-WW1 economy was dire. High unemployment, high inflation and huge debts. Those lucky enough to have jobs often worked seven days a week to make ends meet. There was no spare cash for holidays – family transport was a bicycle or perhaps a motorbike for the lucky ones. It was these circumstances that gave birth to the German lightweight caravan – something that could be used for weekends away by the fortunate few with a small motor car.
Three German manufacturers of the 1930s in particular made an important contribution to European RV design: Arist Dethleffs, Hans Berger and Wolf Hirth.
Arist Dethleffs was a travelling service agent for his family’s business in Isny, south-west of Munich, that manufactured horse whips and ski sticks. Dethleffs married in 1931, but his
wife Fridel soon became uneasy about his long absences on the road. To overcome the problem, she suggested that her husband build for them ‘something like a gypsy caravan that we can travel together in and I can paint in’. So in 1931, Dethleffs built his first Wohnauto, or caravan, to provide accommodation for his family on the road as well as a studio for Fridel. Dethleffs gave the caravan to his wife as a wedding present in 1932. This was Germany’s first-known, motor-drawn caravan.
It was 4.4m long, 1.6m wide and 2.1m high with roof raised. It was simply fitted out with a seat that could be converted into a double bed as well as a bunk bed, table and shelves. It was thoughtfully built, providing ventilation without draughts, safe towing due to its light weight, pneumatic tyres, low centre of gravity and good headroom thanks to its elevating roof. A replica of the Dethleffs Wohnauto is part of the collection of the Erwin Hymer Museum, an RV museum in Bad Waldsee, Germany.
During business trips, Dethleffs would often be asked about his unusual vehicle. One curious onlooker thought it might be a hearse, but a more common reaction was to ask if it was
available for purchase. In 1932 this positive feedback gave Dethleffs sufficient courage to start building caravans for clients in a shed on the family’s business premises. Dethleffs continued to refine his Wohnauto into something more streamlined, and by 1934 prototypes of a new caravan called the Dethleffs Tourist caravan were complete.
The new caravan included a hardwood frame, double panelling and was mounted on a tubular steel chassis with spring suspension. It also included the Dethleffs trademark – a roof that could be raised and lowered. Its biggest asset however was its lightness – it weighed only 430kg and so could be towed safely by a wide range of automobiles. There was sufficient interest in the Tourist to start limited production. By 1936 Dethleffs had a staff of six people producing a modest number of Tourist caravans each year. Dethleffs continued to be a successful RV producer after the Second World War and beyond and was eventually purchased by Hymer in 1983.
Another important German lightweight caravan pioneer was Munich-based Hans Berger, originally a designer and manufacturer of tents and folding boats. Berger felt strongly that Germany had the potential to build better lightweight caravans than any other country because, in his words, ‘Germany is the land of lightweight construction, associated low cost and basic research and has assumed world leadership in the related fields of glider, airship and folding kayak construction’.
In 1930, when on holiday with a Dutch friend who owned an English camper trailer, Berger began to consider how the trailer’s design could be adapted for the German market. A keen camper since childhood, Berger had watched with interest as tents had grown from basic shelters to large outdoor homes. His camping customers asked if he could build them a tent trailer. He agreed in principle but would not do so until he felt he had the right design.
In 1934 Berger developed his first prototype: a lightweight, camper trailer prototype from folding kayak canvas and an old three-wheeled vehicle chassis. In 1935, after much trial and error, Berger felt that the third version of his trailer was good enough to go into production. It was called the Haus Dabei or ‘House with You’ and was, as far as we know, Germany’s first RV to go into limited production. It was a folding tent trailer and weighed only 200kg. Glowing reports of this new type of camper trailer in the German press led to strong sales. The Haus Dabei was simple, efficient, lightweight, easy to tow and more comfortable than tent camping. It received particular praise for its ability to be towed easily up the steep, winding mountain roads of the German and Swiss Alps.
Berger's next RV was the Kajüte or ‘Cabin’. It was Berger’s first ‘full-sized’ caravan built in 1937. It was a folding-roof model weighing only 280kg. It included a letterbox on the front door, perhaps hinting to his customers that they might like to enjoy longer holidays in Berger’s caravans than they were normally accustomed to.
After overseas trips to France and Holland to study the caravans of those countries, Berger succumbed to consumer pressure and developed a Große Karawane or ‘Big Caravan’. But
when customers saw it up close, they felt that its length of 4.6m and weight of 650kg was too great and sales failed to take off.
Berger’s biggest pre-war hit was neither large nor small, but just right. Called simply the Sportberger Karawane, or Sportberger Caravan, it was launched in 1939. It was 3.9 metres long and weighed 430kg. Its headroom was 1.82 metres and it could accommodate two people comfortably and four at a pinch with folding beds. Most importantly, it could be towed by less powerful cars along Germany’s most demanding mountain roads. Just before the start of the Second World War, Berger’s caravan factory was producing one Sportberger Caravan a day and employed eighty workers. After the war Berger continued to produce caravans and camping equipment into the 1960s.
A third lightweight caravan pioneer of the 1930s was racing driver, glider pilot and aircraft designer Wolf Hirth from Kirchheim in southern Germany. Hirth had a passion for glider
flying and design, something he had in common with US aircraft and RV builder Hawley Bowlus (see page 133). In 1931 the two formed a partnership to create a glider training school called the Bowlus-Hirth Soaring School in New York. Both Bowlus and Hirth were aware of the importance of aerodynamics to RV design.
Hirth introduced a number of design innovations into his caravans including monocoque construction, independent suspension and aircraft-inspired aerodynamic design. Other intelligent design features included double-wall insulation, rounded floor to wall
junctions for easier cleaning and a flap and vents for the internal cooking area to reduce smells. A double bed and table combination was adjustable to allow simultaneous sitting and sleeping. There was even an optional front flap for storing kayaks inside the van during travel. Hirth seems to be the first caravan manufacturer anywhere to offer to fit identical wheels to the caravan and tow vehicle, reducing the number of spare wheels to be carried. The Aero-Sport weighed only 330kg, was 4.27m long and 2.14m high.
During 1938 Hirth built a total of 30 caravans. He continued caravan production after the Second World War with a model called the Tramp. His life story is told in a biography by Karl Buck.