montagdude wrote: ↑
Wed Dec 18, 2019 12:04 am
Besides being able to tailor the design to specific operating conditions, another advantage is that I could fix the trailing edge thickness based on the wood that would be used to build it. Of course, that's not to say that anyone could just push a button and end up with something good. It's garbage in, garbage out, and there are a lot of potential pitfalls that require experience to avoid. In the end, an optimizer is just another tool that may be useful for certain purposes.
Yes, I agree. If you don't know what you are doing, better to use some airfoil available. Also most of the time optimisation doesn't make sense as the differences between real airfoil and the airfoil used for the computer design differ too much.
Std Wings which have basically the same conditions for every sections (despite induced aoa at the wing tip) are something already optimized to a point where not much gain in performance can be expected.
One use case I have in mind is a horten wing. These kind of wings have different aoa at every section. So it makes sense to use also different airfoils at each section. And at the wing tip some airfoils can help to reduce the negative yaw momentum (at least this is what I experienced with 3 prototypes.) As this airfoil is acting at low aoa you might want to optimize towards low drag at low cl and high drag at higher cl's. The problem with negative yaw momentum is introduced when the airplane rolls which leads to higher aoa at the side which moves downwards. This leads to higher lift pointing forward compared to the center of the wing. The same thing happens on the other side but in the opposite direction. This results in the effect of negative yaw momentum.
There are some ways to fight this. Negative aoa at the wing tip is what works best but is not good for performance. Using winglets or find is the traditional way (tailless wings). Optimizing the tip airfoils drag to introduce positive yaw momentum might help to reduce the negative aoa needed at the wing tip.
So that's my motivation for the optimizer. I know what worked best in reality (testing 3 different airfoils). So the start geometry is known. Looking at the conditions when a turn is introduced it might be possible to find a better design which helps to reduce the geometric twist (performance) or decrease the measure of stability (higher max lift).