Video: Funktionsprinzip AFS
(AVI, 12,8 MB)
AFS-Schema Normalflug
AFS-Schema angebremst
Auftriebsverteilung
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To paraglide with lots of fun and have the highest level of security possible, this is the promise of the revolutionary AFS-System (Automatic Flight Stabilisation). It intervenes for the benefit of safety when an inexperienced pilot, or a pilot in trouble, enters turbulence and is unable to fly actively. AFS works like the Electronic Stability Programs known in the automotive industry, you could call it an “ESP for the air”.
By implementing many technical innovations, designer Ernst Strobl entered a new dimension in glider design, having invented both the Improved Stabilisation System (IST) and the Multiple Speed System (MSS). Strobl now presents a paradigm shift: For the first time a designer has managed to allow safety to happen automatically to a certain extent.
The core innovation of the AFS-system is based on the principle of pre-tensioning the undersurface at the trailing edge. “This idea I had during a flight”, Strobl recalls his sudden inspiration, “It must be possible to pre-tension the under-surface by making sure of an exactly calculated cut – so that on the one hand the canopy is neutral while there is enough pressure inside, but on the other hand any drop of pressure causes the system to react”.
Dozens of computer-based calculations with high-end software from the aviation industry allowed the break-through to be achieved. A special production process around the brake attachment points leads to the desired effect. Whilst the canopy is gliding through smooth air and there is enough pressure inside, the pre-tensioning is neutralised and the trailing edge stays aerodynamically perfect like a conventional glider.
When entering turbulent air with the BODYGUARD the system adjusts immediately, even the slightest drop of internal pressure allows the system to react. The pre-tensioning at the trailing edge is effectively like pulling the brakes.
A canopy featuring the AFS-system reacts without any steering or braking action from the pilot exactly in the way that the safety experts of the DHV recommend: It flies actively and therefore safely. Ernst Strobl recalls the fine-tuning, “Our computer-based calculations were impressively confirmed during our tests”.
The system is extremely responsive and top-quality manufacturing is necessary. U-Turn Co-founder Thomas Vosseler adds, “We will guarantee a strongly supervised manufacturing process”.
Andreas Schubert, of the “Rhöner Gleitschirmschulen”, who has taught 10 % of all new pilots in Germany over the last ten years confirms, “This is a major step as far as safety is concerned. The main reason for accidents, the full collapse of the canopy, is minimized dramatically”.
The principle of the pre-tensioning of the canopy led Strobl to more design improvements. AFS works best in combination with the geometric setting of the profiles. This means that the profiles do not run lengthwise along the canopy (90 degrees to flight direction), but at an angle between 80 and 100 degrees, allowing every cell to perform in the optimal way. Furthermore, Strobl did not design the width of the cells uniformly; he used a very fine tuned asymmetry that also required lots of computer power to calculate. Strobl calls this dynamic cell-width reduction. In a third step the whole system works more efficiently by using a swept-back design of the wing tips.
Together these innovations lead to better characteristics under normal flight conditions. “First I have to mention the optimal start behaviour,” says Strobl, “The first glider providing the new system is called BODYGUARD; a DHV 1 glider that will set fantastic benchmarks. The BODYGUARD is easily to inflate in all kinds of wind; there is no need for pulling the A-risers or other tricks and it is impossible for the canopy to become stuck before the overhead position. Inflation is easy even for beginners and due to the AFS-System the canopy sits right above the pilot. If the canopy falls backwards, the BODYGUARD comes up immediately after releasing the brakes – even at angles where other gliders give up”.
The new construction principle also automatically improves the stall characteristics in flight. Pilots can slow down the BODYGUARD to very low speed without having to lose manoeuvrability. The newcomer will come to terms and feel comfortable with an AFS-glider on the first flight for another reason: “The wing tip comes slightly forward when the brakes are pulled”, Strobl explains, “the canopy sits right above the pilot and this effect can even be seen while Paramotoring, this is what inexperienced pilots will appreciate”.
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