The problem with diving a 65mm or 75mm is the prop guards. It creates all sorts of weird air movement and it doesnāt so much dive as fall randomly. Iāve dived a Meteor85, sort of. Down a tower, but the first time it was crazy and was more like tumbling as it fell. Second time I left about 10% throttle on and it was better controlled, although your dive is now a power dive, but itās still technically a dive. I did want to try it at 50-100% throttle, but considered it to be marginally too dangerous, to dive a 12 storey tower at 30-40mph.
The Emley Moor transmitter dive that someone did the other month was on a 2" and that was tumbling every which way, not that Emley Moor is known for calm air movement. I think you need a reasonable amount of weight to dive buildings, just due to the weird air flow you get when air hits a square shape and splits, probably not in an even way, creating weird vortexās. So probably at least 100g and ideally 150-200g. I know on 85mm itās not ideal without some power. On 65mm, you should probably apply at least 50% and if you can increase camera angle, do so, so when you are diving, the quad base is almost flat and therefore all power is pushing down and not partially away from the tower.
Now diving a 65mm down a street light is less random, but still not ideal. Probably because the gauge of the tube is less and generally round, so air movement is less turbulent.
Also the key to pulling out of a dive is to apply the throttle gradually, unless you are trying for a suicide type dive with the aim of getting as close to the ground without hitting it. My aim is to start pulling out at about 8m, with an aim to be maybe 1m from the ground at level, but my throttle is applied gradually from probably 15m, so by 8m Iām at maybe 10-20% throttle and pulling out. I donāt want to stop momentum, I want to redirect it.
The other thing(s) it depends on are, well, the whole quad. If you build a quad with motors that generate a full kg of thrust with a total weight including battery of 200g, then it will pull up real easily. if you used even more powerful motors, you might not need to blip the throttle as much. But if you dive something with underpowered motors on a heavy frame, then it might be a 100% throttle to avoid cratering. Everything I try to build is pretty much overpowered. Even stuff like the BNF Meteor85 is OP (2S on 1103 11000kv) and it is hellishly fast for itās size. Light frames, powerful motors, but the trade off is less flight time, but new underwear level fun.
Anyway iām typing too much. 