=Cartoon Report=
First Ever in the World
Sterling Techno Rally
- Old Yet New External Combustion Engine -
Report : Taichi Ozawa / Illustration : Nobuya Akamatsu

For this time, I visited the Technical High School attached to Tokyo Institute of Technology in Tamachi, Minato-ku in Tokyo to see the 1st Sterling Techno Rally ( self-made Sterling engine car contest ) on June 31, 1997.
In the contest, high school students and the general public brought along their model automobile running on a self-made Sterling engine to run a set course and compete in time. This must have been the first competition in the world of only Sterling engine cars.
So what is a Sterling engine? It is an external combustion engine invented by an English vicar Robart Sterling in 1816. 1816 is a long time ago. This ancicent engine is once again drawing widespread interests. The Sterling engine heats the Cylinder from the outside and cools it to expand and contract the air such as helium gas inside ( only normal aie could be used in the competition. No helium nor hydrogen was allowed ) and move the piston to produce power. But it is not leisurely heating the cylinder to expand the gas inside, then cooling it with water to contract the air, then igniting and cooling again. Most of the mchines of the teams participating in the contest heated the end of the piston constantly with a burner. So the mechanism is one in which the gas inside is moved skillfully, cooled at a different place, and the difference in the pressure caused by the expansion and contraction is obtained as the power cleverly. I am going to stop with the description of the theory for if I go any further, I may say something wrong. The important thing is anything can be used for the heat applied from outside as long as the required temperature difference can be obtained.
The contest was held at school's gym. Five course lanes of 13m long were set up in the gym. The Sterling engine cars which had been inspected raced through these lanes and their times were measured using a PC.
The size of the machine was 60cm in length by 28cm at the maximum. No limit was set for the height. Though they were called models, only some were like the miniautre cars ( shrunken versions of normal cars ), and most were just engines on wheels. They also came in various sizes, with some as large as was allowed while others were so small that I could hold them in my hand. Most used the gas burner as the heat source. Some mounted the heat source on the car body. I also saw some engines run by the residual heat flamed until just before the race. maybe to reduce the weight. Some used the solid fuel you see in restaurants for keeping small pots and bowls warm on the table. Unlike the internal combustion engine using explosive power, the engine is very silent producing only a slight rattling sound.
This competition, the first of its kind in the world, drew about more than 120 teams. Not all teams that applied came that day, but the number of participants was more than the organizers had expected. At the beginning, It was considered that if someone could run the 13m couse in 6 seconds, it should be a great record. But the four winning machines recorded a speed of 4 seconds. Coupled with the summer heat, the gym was alive with the excitement of the participating teams. It shows how much the Sterling engine is currently attracting attention.
So what was the aim of the competition? First the Sterling serves as an excellent means of teaching the students the function of heat clearly. It also prevents the young from steering away from science. This is an alarming problem that Japan a technology nation faces. Regardless of such educational effects, the expectations towards the future of the Sterling engine is big. The Sterling engine has a simple structure, and heat efficiency is good.
Also though more than 180 years have passed since it was invented, it is true that development to put it to practical application have been slow. One of the reasons is the leakage of gas in the cylinder. Recently, it seems the sealing material to prevent leakage has improved considerably. In whichever case, since the heat source can be anything, natural energy such as solar energy and unused energy such as waste heat can be combined to develop a "new energy engine." It need not only be used as the engine of automobiles, but for running power generators as well. This is indeed an "innovetive use of conventional energy" that has been advocated by the "Basic Guideline for New Energy Introduction." The Sterling engine is truly an old but new engine. I hope this competition helps to open up its future.