Supero Science, 101
In which we summarize the contributions of Bernoulli, Newton and Coanda to our understanding of aerodynamics…
So how do our resident genius experts stack up?
His equations work well in an ideal fluid with no boundary layers, where the surface is a streamline, the velocity of the fluid is low, and no energy is added to the flow. (Important to note that physics treats air as a fluid.) Bernoulli’s equations work fine to determine pressure/velocity distributions. But when boundary layers are present – e.g., with real airplanes – it gets a lot more confusing and the Bernoulli equations can supply only part of the answer. This is when we have to turn to Newton… and Coanda.
Let’s review Newton’s first, second and third laws, and then see how they apply to lift and flight.
- A body at rest will remain at rest, or a body in motion will continue in straight-line motion unless subjected to an external applied force.
- Force equals mass times acceleration (F=ma).
- For every action there is an equal and opposite reaction.
Applying these to flying:
- If air is bent downward by an airplane’s wings – e.g. downwash, which is clearly demonstrable and often visible – then some force is acting on the air.
- That force is determined by the mass of the air and its velocity, multiplied together. Phrasing this in terms of lift, it is proportional to the amount of air diverted down times its vertical velocity at any moment in time. Keep in mind the importance of the word “times”.
- The air moving down behind an aircraft’s wing is the action; lift is the reaction. Not only is it true that “what goes up must come down”, but in terms of lift, when something is forced down (air), something is forced up (flying machines).
Here’s where things get really interesting. Father of the jet airplane (1910), builder of a working flying saucer, discoverer of the effect later named after him, the “Coanda Effect”, which has been used in many aeronautical inventions – though none quite like what we’re working on. And consider this quote from him: “These airplanes we have today are no more than a perfection of a toy made of paper children use to play with. My opinion is we should search for a completely different flying machine, based on other flying principles. I consider the aircraft of the future, that which will take off vertically, fly as usual and land vertically.” His vision then, our vision now.
The Coanda Effect is most simply defined as “the tendency of a fluid jet to be attracted to a nearby surface”, keeping in mind that in these terms air is considered to be a fluid. (As a well-known science site puts it: “To put it simply, a salmon essentially flies through the sea, and a pelican swims through the air.”) You can stick the backside of a spoon into the flow of water from your kitchen faucet and see the effect in action. Ever thrown a curve ball, or tried to hit one? Hooked or sliced while golfing? If so, you have experienced the Coanda Effect.
Coanda discovered it when he fired up his “Coanda 1910” reactive-engined aircraft and noted that the hot exhaust was curling in to crisp the sides of his front-engined craft, rather than flowing straight back. Of such mishaps are great inventions made – when they happen to the right person. The key to the effect is “entrainment” – a word you will see mentioned again on our Technology and Test pages, and defined on our Supero Science 301 page, as it is central to the results we have achieved.
Current commercial applications utilizing the Coanda Effect range from improving the lift capability of flaps on aircraft to air-conditioning. But this is evolution. We’re working on revolution. We believe that with the right design the potential exists to revolutionize the business of flying – as well as other industries. And we have the data to back up that claim.
In sum, each of these great men, and the physical effects that they discovered/described, supply some of the basic answers to the question “what makes airplanes fly?”. But when it comes to the patented amazing technologies that Supero is developing, Newton and Coanda supply most of the explanation. More information can be found on our References page. But first, please go to Supero Science, 201: Coanda Implementations, and then Supero Science, 301. After that explore our Technology, Test, and Graphics pages to see some pragmatic results. Consider it our version of ground school.