Physics in air warfare that is. I had to read some basic physics to remind myself of the rules of basic Kinetics, as it turns out that I can't properly understand the flight mechanics of WW1 dog fighting without it. Specifically I was looking for the rules on converting potential energy into kinetic energy (trading height for speed) and how fast various 'planes would gather kinetic energy in a dive and then shed it again once they leveled up. I also need to know how many g they experience in the pull up to see if structural damage is an issue.
It turns out its pretty meaningless other than as a very general rules because its almost impossible to decide what the VNE rating of the majority of WW1 aircraft was. VNE is 'vitesse never exceed' aka 'velocity never exceed' in aviation jargon or what we would think of as the safe limit for dive speeds. There are some useful anecdotes about that speed for a handful of aircraft but that's about it. I suppose flight safety limits were a bit more elastic back then.
For example Bristol Fighters were built to handle a 6g load and had a design max safe dive speed of 400 mph! Certainly diving at speeds close to 300 mph seems to have been common for them. SPAD 13s could also dive at those kind of speeds. It has calculated that V strutters like Nieuports and Albatri DIII and DV would shed their wings due to 'flutter' (undampened oscillations in the lower wings) at 135mph. My favourite though is the description of how to dive in an SE5a.
"After we had learned to handle the S.E.5a's fairly well, he called us together and said, "Now, I want you to do some fast diving with your engine full on, and diving vertically. You can get up to nearly 300 m.p.h., but I must tell you how to do it without losing your wings. The airspeed indicator only registers up to 180 m.p.h., so after that has been passed, you simply look at the fabric on the lower wing. When you see one buckle appear in it, you are probably doing something like 200 m.p.h.; when there are two buckles, you are probably doing about 250 m.p.h.; but you want to be careful not to get three, because then the wings will undoubtedly fall off. Now, go up and do some real diving."
The SE5a was able to dive to something close to 275 mph. What I have been able to find is that the terminal velocity of most WW1 aircraft was low due to the inherent drag so most of them seem unlikely to have been able to reach the VNE limit unless in a steep dive under power. The real risk was the g load on pulling out of powered dives. While British and French built aircraft appear to have been designed with 6g loads in mind, early war German aircraft may have only been built to handle 3.5g (according to an article on the Aerodrome website). Their ability to hold energy after leveling out from a dive was hampered by two things, they didn't gather much energy in a dive because they had little mass and the drag factor meant the velocity was low (the energy gained is dependent on the mass of the objective times the velocity squared). That high drag factor also means they bleed energy quickly after leveling out so it needs to be utilised quickly at the end of the dive.
What that means is I can fudge the equations to create generic energy rules. Which is good news for me as I don't think I was listening the week we did calculus either and that is what I would have needed if all the data was available.
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