Introduction
Working through the checklist before the start is obligatory. Of course, you should understand what effects the individual points can have too. |
Models in Nature
It can be assumed that birds do not have a deep understanding of aerodynamics. Also experience and training plays a subordinate role for them. Amazing how the characteristics and genetic predisposition puts them to survive the first flight reasonably undamaged in this situation. They also do not have to worry about the flight stability, the possibilities are already constructively setted.
Designing, building and flying are independent disciplines. Happy is he who can unite everything. |
A designer must not give technical evidences of strength only - but also flight performance and stability relevant evidence before the construction can be started. Similarly, when modifications of existing aircraft. Apparently minor modifications can affect the flight behavior and the stability. Who does not have intimate knowledge of aerodynamics can not even decide whether the changes make sense at all and allowed are - possibly they are even dangerous. "Try and error" can use in building model aircrafts - and that makes inter alia the charm of it - but not accepted in the manned aviation.
Lift collapse (stall) in the flow tunnel |
Aircraft and racing vehicles are largely highly developed today, so if you want to achieve improvements here, you have to deal with the details. If the general understanding is not right, you won't get very far. The biggest obstacle to leaving the well-worn paths of thought and half-baked school wisdom is the consistent non-use of the term "flow" (airflow) when it comes to explaining dynamic lift. More information on this later. The term "flow" (airflow) is hammered into us again and again. It is true that there are parallels between reality and the wind tunnel. However, if you want to understand exactly what happens, e.g. in a "stall", which is actually a change in pressure conditions that leads to a collapse of lift, then you must not mix up the inertial systems. In English, it is easier to use the term "stall". In German, everyone is invited to suggest alternative terms (instead of "Strömungsabriss" and "Strömung".
Since it is primarily a dynamic air pressure system around the aerofoil and in particular around the aerofoil cross-section and the small displacement paths of air particles are disproportionate to the movement of the aerofoil itself, the term "flow" is misleading. For the time being, "pressure distribution" (the flow => the pressure distribution or, more precisely, the dynamic pressure distribution) and "lift collapse" (the stall => the lift collapse) are proposed. Admittedly not quite as elegant, but more correct and with the same articles (in german language), so that the terms can easily be exchanged.
| ⇒ Cause and effect