Fokker D.VII, for example, I find anything below 130kph difficult to maintain with smooth flying.
For example, I just did a run with the D.VII at 130km/h, your optimal climbing speed. Sometimes it varied from 125 to 135km/h, since it felt wobblier. The result was:
500m - 1min35s
1000m - 3min19s
1500m - 5min24s
2000m - 8min02s
2500m - 11min35s
3000m - 15min04s
3500m - 20min27s
If you compare with my run at 110-115kmh (see the data box) you are going to note that they look like completely different planes on the climb department.
Your speed might work for a "cruiser climb", but it felt it wobblier and difficult to maintain at 130km/h than at 110km/h. And when you spot a foe at the distance and you know that he / she saw you as well, you need to climb as fast as you can, and in this regard I would definitely put my plane hanging on his prop at 110km/h, no question about it.
Regarding the methodology, I didn't come up with the speed by chance or by the "feel" of my stick. I did several runs with each plane in different speeds, and I settled with the speed that climbs the best. IIRC, I must be done more than a dozen runs with the Camel, since the data was so absurd that I thought that I was doing something wrong. But of course that people might find some errors or inconsistencies. It is just a test.
What you might be referring to is that what I have observed is that each plane has a speed where they seem to "go by themselves". Which means, they don't wobble, they don't struggle that much. Some other planes climb better close to the edge of the envelope, but they also "run by themselves". I don't have to do much with the stick, especially after 2000m, when I think the atmospheric simulation makes them literally hang on their props. This is best felt with time constraint.
One thing that I am finding interesting with the tests is to understand the physics of the planes by the developer's point of view. You start getting some feedback like a test pilot would get.
If I may ask a question, why did you place time on the Y axis, rather than the X axis?
FourSpeed, I am playing around with it but I don't seem to find a way to make the switch. I have looked for tutorials, videos, but all I can do is switch the "axis" altitude X plane names. If you check the data box, Excel reads the name of the planes and the altitudes as the axes that I can swap from X to Y. I tried to place the data in different arrangements, but Excel always read X and Y in the edit box as the name of the planes and the altitude.
Anyone else knows how to do it? There is a chart attached for who wants to play with it and reattach back so we can take a look and see how it was done. D.VIII and Hanriot are in the same line because the run is almost identical. But whenever I put together a chart I discriminate the data on the data box. Just the line remains the same.