Whale kinship

August 11, 2020

In prototypes of the Boomerang 12, Gin is experimenting with protruding wing leading edges that are reminiscent of the fins of humpback whales. The fins of a humpback whale have bulges on their front, so-called tubercles. A prototype of the Boomerang 12, with which Michael Sigel flew at the Swiss Championship, imitates this shape. // Source: Wikipedia - Whit Welles, Martin Scheel Nature has often served as a model for technology, especially since evolution usually provides very efficient solutions. It is possible that some paragliders of the future will have a special feature that is inspired by humpback whales. These whales have conspicuous protuberances, so-called tubercles, on the leading edge of their pectoral fins. And these are currently also available, somewhat modified, on prototypes of the CCC Boomerang 12 umbrella from the Korean manufacturer Gin. Such a glider was recently shown at the Swiss Championships in Fiesch, where Michael Sigel flew with it (albeit a little less sporty than perhaps hoped for). The tubercles of the humpback whale fins have enjoyed a great deal of attention from aerodynamicists for several years. Simulations of the flow conditions around the fins show that these protuberances on the front have a beneficial effect on the flow around the wing-like fins in several ways. Flow simulation on a normal and a turberkel wing. While in a normal wing the flow breaks off in a line, the flow break off behind the tubercles is diffuse. // Source: Frank E. Fish et al. The tubercles generate parallel flow eddies over the wing, which canalize the flow between the eddies. This has several effects: On the one hand, the flow breaks off later and never as suddenly as with a straight wing - because the tear-off point lies at very different wing depths behind a front hump or the depression in between. The strip-like "channeling" of the flow along the profile also suppresses disruptive cross currents which otherwise only increase the induced drag and thus reduce the lift of the wing. Theoretically, the tubercles could also increase efficiency. (You can read more on this topic here). Can all of this be transferred to paragliders in an advantageous way? There is still no clear evidence here. Torsten Siegel, designer at Gin, reveals only this much so far: "We are working with a Korean university on various prototypes and are investigating the possible uses. Michael Sigel tested the last draft for us at the Swiss Championships so that we can continue with the feedback and the determination of the situation can work." A prototype of the Tripleseven King from 2012 had narrow outer wings. // Source: By the way, Tripleseven Gin is not the first manufacturer to be inspired by whales. A few years ago, Tripleseven experimented with prototypes of the EN-D King with wing structures in which the outer wing was much narrower than the middle wing. The ultimately approved King had a conventional shape. However, this development coincided with a time when, after the official end of the so-called open class, there was a great deal of wrestling over the approval rules for competition umbrellas. This also included the limitation of the wing extension. Competitors from Tripleseven saw the narrower (more elongated) outer wings of the King as an attempt to undo the extension limit. They then made sure that non-stepped wing shapes were prescribed in the rules. The whale design inevitably ended up in the drawer. Whether the tubercle design of gin would even be permissible according to current CCC rules remains to be clarified. A possible dispute about this is only likely to ignite, however, if the experiments with the prototypes actually show noticeable advantages. Are you inspired by such technology news? Lu-Glidz provides a cornucopia of current information about paragliding. All of this is available online. But that doesn't mean I'll just give it away. I live from the fact that I earn my money as a freelance journalist. And Lu-Glidz is not just a hobby, but a journalistic project that also contributes a (still only small) part to my income. In Corona times, however, this is very welcome. If you want to continue reading Lu-Glidz so freely in the future, then please become a sponsor. How much you want to give as a contribution is entirely up to you. If you are unsure, I recommend two euros per month of reading on Lu-Glidz as a non-binding guideline. Payments can be easily made by PayPal or bank transfer (also by standing order). All the necessary data is on the side: funding.

This article has been translated for your convenience and was originally written in Deutsch.