Jet airplane


Nowadays it is much focus on getting the fuel consumption and emission from the jet airplanes down. Most people engaging in this are mostly focused on the airplane shape and that is of course excellent, but in my opinion we must choose a different angle of approach to the problem to get the necessary radical changes. If we really shall step up the process of reduction of the fuel consumption, we must to quite another extent use the propelling machinery as a basis, because it is the engines that consume large amounts of fossil fuel, emits CO2 and makes noise. Are there possibilities for great improvements?


Sir George Cayley, the inventor of the science of aerodynamics, was building his first models of airplanes as early as 1803, and he built his first successful passenger-carrying glider in 1853. In 1856, Frenchman Jean-Marie Le Bris made the first powered flight, pulled by horses on a beach. Self-powered aircrafts were designed and constructed by Clèment Ader in 1890.  The Wright brothers are commonly credited with the invention of a powered controllable aircraft and made their first flight in 1903. The first commercial jet airplane, De Havilland Comet, was introduced in 1952. In 1969 the jumbo jet aircraft, Boeing 747, lifted for the first time and it is still offered with nearly the same design as for 40 years ago.

Le Bris and his glider
Le Bris and his glider, Albatros II, photographed in 1868.

What is wrong with the jet airplanes and what can be done better?

After a careful study of the complete technical solution that the manufacturers use, my opinion about what is wrong can in short be summed like this: They lack complete continuous variable gear between the jet engines and the turbofan thrust giving turbines.

  1. The jet airplanes must get the fuel consumption down.
  2. The jet airplanes are today flying fuel tanks. An example to illustrate this (The ratio numbers will be about the same if we use another airplane type and make.): A jumbo jet has weight data as follows: Maximum takeoff weight inclusive passengers and fuel is 400 metric tons. In this, the fuel weight is as much as 200 metric tons. That is, the half of the takeoff weight is in fluid form. As a comparison the 400 passengers with luggage weights only 40 metric tons. Do the thought experiment that the engine manufacturers managed to make propelling machinery that reduces the consumption with 50 %. Then it would only be necessary to carry 100 metric tons fuel. The weight of the airplane would then be reduced to 300 metric tons. But then you could remove half of the fuel tanks. Since the fuel tanks with equipment, walls, and stiffening devices for sure weights 120 metric tons, 60 metric tons will automatically disappear. That means that we now have reduced the weight to 240 metric tons. We suppose that the airplane engines with fixing devices, wings, wing supports, part of landing gear etc. weights 80 metric tons. That will mean that if we halve the airplane weight, 2 of the 4 engines can be removed. That is, we can remove another 40 metric tons. Than the Jumbo jet weight in this case is down to 200 metric tons. We need, as we have supposed earlier in the example, only half the wing size. We only need half as strong landing gear etc. And as you can see, we will manage with only 2 engines instead of 4. Why do I mean this is possible? Why have the manufacturers not done this before if it is possible? The reason is that it has not existed a solution with complete continuous gear that can be used between the jet engines and the thrust giving turbines in the present turbofan airplane jet engines. That exists now. See web:

  3. Why will the fuel consumption be reduced 50 – 80 % with variable gear?
  4. We first look at the present solution with jet engine, without gear, with bypass thrust giving turbines that drives the airplane forward. The jet engines must then be dimensioned so that the bypass-propeller-turbines manage to give sufficient thrust to accelerate the airplane on the runway and lift it to cruising height. In this phase we must have engines with maximum thrust, while the airplane moves slowly, 0 – 180 mph (0 – 290 km/h). The air pressure is 1 bar. After takeoff, the speed increase to 560 mph (900 km/h) that is common cruising speed for the present jet airplanes. The air pressure is here approximately ¼ bars. Here the problem is in a nutshell why the fuel consumption is this far too high. The airplane engines must work from standstill on the ground to 560 mph (900 km/h) in the cruise-speed height. It speaks almost for itself that this cannot be done in an optimal way without complete continuous variable gear between the engine and the thrust giving propelling turbines. The airplanes must have very large engines to get sufficient thrust for the airplanes to lift and move to correct cruising height. After 10 to 20 minutes the airplane has reached cruising height. Then the plane needs a thrust of less than 1/6 of what is needed during takeoff. But the bypass propelling turbines must rotate very fast to keep the airplane speed in the cruising speed of approximately 560 mph (900 km/h) during the rest of the flight, which often is several hours, until the descent begins. Therefore the jet engines must race to an entirely unnecessary number of revolutions during the most of the flight with an excess consumption of fuel as the result. The jet engines must have continuous fuel supply that is in proportion to the air passing through in order to keep on. If the airplanes became equipped with complete continuous variable gears between the jet-engines and the bypass-propeller-turbines, then the jet engines could have been run at high speed and high power during takeoff. By means of the variable gear we could adjust the number of revolutions on the propeller turbines so that the propeller turbines work optimally. As the airplane speed gradually increase and the airplane lifts, the computer that controls the engine and the gear will continuously adjust the gear ratio so that the propelling turbines always work perfect in accordance with the flying speed. When the airplane have reached cruising speed height, will the engine rpm be reduced and the gear ratio adjusted so that the propelling turbines always keep the airplane in correct speed with as low engine rpm as possible and thus as little fuel consumption as possible. Since the airplane is in cruising height the most of the time, the total fuel consumption will be greatly reduced and the reduced fuel consumption will make the airplane lighter so that the takeoff weight will be much lower. In addition the wing air-resistance will be much lower through the whole flight because the wings are smaller. And then the power need and thus the jet engines and the fuel consumption will be strongly reduced during the whole flight. It should absolutely be possible to reduce the total fuel consumption with 50 to 80 %. This is so much that this solution will be taken into use because the fuel expenses for the airlines will be heavily reduced and the fuel cost is today a substantial expense for the airliners. In this way the aviation can easy take their share of the total global CO2-emission reductions without any cost. They will in fact earn heavily on this because in addition to saved fuel expenses the airplanes will have much lower price. The airliners will consume considerably less fossil fuel. The engine wear and the engine maintenance will be strongly reduced because it will be smaller and in total fewer and they will rotate slower and run more correct the most of the time. The criticism against the airliners about wasting and polluting will almost disappear. Cheaper ticket prices and newer airplanes will be the bonus to us passengers.

  5. Far too much noise
  6. The present airplanes make far too much noise. This is to a large extent because the manufacturers have had to compromise with far too big jet engines and bypass propeller turbines that do not run with optimum rpm especially by takeoff. When we start to use the variable gear, the propeller turbine will always run correctly. Therefore the noise will automatically be reduced to quite another level than today. This will be a great pleasure for the airport surroundings.

  7. Lighter airplane body
  8. When the airplane weight is halved, the strain on the wings, wing holds, landing gear, wheels etc. will be much less. Then it will be natural to use much more composite materials in the airplane bodies and the weight will go further down. One will get further a strong reduction in use of aluminum alloys and other materials that is expensive and energy demanding to produce.

  9. Better aerodynamics
  10. When the airplanes need much smaller wings in proportion to the airplane body, I take it for granted that the manufacturers evaluate the airplane body, the wings and the aerodynamics around the airplane with fresh eyes. Because these conditions are also far from optimum on the present airplanes and it is obvious that this must be changed when the turbofan engines with gear are taken into use.


It is absolutely possible to produce airplanes only few years from now with fuel consumption that is 50 – 80 % lower than today.
The airlines will then get much cheaper airplanes, lower working expenses and maintenance.
This gives increased earnings for the airlines and cheaper tickets for the passengers. The emissions and the destruction of the climate caused by the aviation will be dramatically reduced.


The jet airplane is a fantastic construction that, in a way completely different from any other means of transportation has united the world and made it smaller. It has given the basis for that people have learned to know each other and foreign cultures much better and made the foundation for mass tourism. The jet plane has given the opportunity to close contact between politicians and business people throughout the entire world and this will lead to fewer wars at the same time as it gives more globalization and less hatred to foreigners. To give the possibility for all to take part in these great advantages, this large increase in the efficiency is a quite necessary condition. The beauty of such a reduction of the consumption is that it does not reduce the comfort, the pleasure of flying, the prosperity or all these other benefits the airplane gives to the world. On the contrary, many more can achieve the same prosperity benefits.


If you have views, please contact us on

© Tron-Halvard Fladby/ 2007.08.07