for me.. i produce the most power when i'm doing it naturally. jumping and then swinging the arms to hit the birdie just doesn't cut it and it feels odd. i think just work on your not-jumping smash first and slowly develop ur jumping smash execution. sry if that's not much of a help, i can't really describe the "natural" process of jumping smash
in my opinion, for a long term and important match, the jump smash is not very uselful, first its hard to do and sometimes you may injure urself by accident or lack of practice, and its only when you do it perfectly will you generate more power than a normal smash Also when you dont do it well, it will be returned easily and then you wont be a in good position to recover and defend, and it wastes alot more energy than a normal smash, which is more consistent than the jump smash
a jump smash isn't about developing more power than a normal smash, from my experience, it is about developing more angle, making it more difficult for your opponent to return.
i found it hard to jump smash until earlier this week when i finally had it as good as i could get it. going up i bend my knees, have my racket up and jump. while i'm in the air my heels go back and my left arm goes out for the aim. when i smash, my legs come back out straight and i turn my waist, as well as my head to the left(i'm right handed) so my right arm goes up higher. then i can snap my wrist and execute the smash. after doing the smash, my left arm goes back and i land on *both feet.* i'm not so sure about the landing. i have been told that i should land on my non-racket foot.
I dunno if this helps or not, since my own jumpsmash isn't very good, and I only do it when I'm not playing very serious or when there is a really high lift. sometimes my friend and i get bored, and we try to practice jumpsmashes... person 1 smashes, person 2 drives it back, person 1 lifts, person 2 smashes... etc until one of us gets too tired to continue I dunno if its supposed to come naturally, but it did get a bit smoother after a while and my timing is better, though i barely lift off the ground lol before i jump i prepare by bending my knees so i can get a bit more height in my jump... that might help.... personally i don't jump very high so i never get to bring my heels back.
Jump Smash Jumph as high as you can and try to hit the shuttle at this peak point. It will produce a steep smash that is hard to be return. yet doing jumping smash will consume you a lot of energy.
lol, i got the calf muscles for jump smashing coz ive been riding a bike to school for 7 years =), i just cant seem to swing my arm fast enough, plus i cant get the angle