Here's another brief film demonstrating loops in the P-38G and F4U-1D. The film is zipped.
Both begin by taking off and leveling off immediately. As air speed passes 140 mph, the fighters are pulled into a loop. Typically, speed peaks at about 145 mph (as seen on E6B).
Most people would not recommend looping from nearly ground level, but it can be done without undue drama in a limited number of fighters. Just remember to pull off power on the way down.
Spitfires (any model) can't remain in plane, and invariably fall-off to the right, not being able to complete the loop headed in the original direction. Zeros do it well, as one would expect. The Hurricane Mk.I can do it, the but the Mk.IIC doesn't do nearly as well. You'll find the Ki-84 can do it, but can't remain in plane like the P-38G or f4U-1D/F4U-4. The Macchi C.202 can't do it at all. Another that does it well is the F6F-5, but the FM-2 falls out of plane more. I tried the Bf 110C. It was able to do the loop, but fell completely out of plane.
One surprise was the La-7. It was able to perform the loop and generally remain in plane, nearly as good as the F4U-4. It was significantly more stable at the top of the loop than any of the Spitfires. All were tested with 25% fuel, 1.0 fuel burn.
Here's the short film
loopers My regards,
Widewing