elytra flight profile -- as long as you hit each angle to within 10 degrees, with less than 5 degrees of additional systematic bias, and as long as you can time yourself to within 20%, with no more than 10% additional systematic bias, then this will very likely allow you to get infinite flight. if you can pull it off perfectly, you'll gain altitude at 2m/s
units in degrees
for 3 seconds: 30 down
for 4 seconds: 40 down
for 1 second : 55 down
for 1 second : 0
for 1 second : 55 up
for 1 second : 30 up
for 1 second : 20 up
for 1 second : 15 up
for 2 seconds: 10 up
repeat
it should look something like this
(horizontal on x, vertical on y, each dot is separated by one second of flight)
edit: just tested this in game and got about 7 meters higher than i started, which is decent because i don't have superhuman precision