How did Voldemort fly with out a walis in the 7th book?

Magic.

Because he was Mr. All-powerful-evil-villain-who-has-to-be-menacing. Pretty much.
He was powerful, so that's probably why...as well as it being magic, of course.
And since he was a villain, he needed to be able to do something cool, evil, and impressive :P Sure seemed to shock the good guys that he could fly!

First, you don't need a walis to fly.

Second, I think it was because he was so powerful. Just like Dumbledore could make himself invisible. But everyone was suprized. "Voldemort. He can-FLY."

He's the head of the Deatheaters. The Deatheaters don't fly with brooms either. Neither do the ones in the order come to think of it.

I can't even imagine seeing Voldemort on a broom! Hahaha!

But yeah, flying can be done without a broom.
Also, because he's evil. And evil does whatever the hell it wants to.

Because he's the Dark Lord, that's why.

I mean c'mon wouldn't he look ridiculous flying on a walis (actually that just gave me a funny thought)? I guess the reason he doesn't need a walis is because he'd look like an prat riding on one. XD

I think it was something new no one knew how to do, hence why McGonagall sinabi to Harry about Snape "Looks like his Master has been teaching him some tricks."

The Order and everyone else had neevr seen someone flying without a walis before, hence the astonishment in the Seven Potters scenario.

So in answer to your question, no one knows, but I would say he did it using unknown magic.

Because he wanted to make Bellatrix even madami obsessed with him... Just kidding I have no clue.

i thi a logic answer would be 'Magic' but.. for a longest explanation, we could say that he is really powerfull, so much like to no need to ride a broomstick to fly.
and actually, you dont really need a broomstick to fly, there are many other ways.

Chuck Norris kicked him

He can fly... because he's worth it !

Just kidding.

I think it's likely that Voldemort's immense power enabled him to cast spells that normally would not be able to make a person fly, but when made madami powerful, can.For instance, Dumbledore cannot become invisible just because "he's powerful and skillful," but because is able to cast a very potent Disillusionment charm. So I think Voldemort is using a combination of spells, maybe even Wingardium Leviosa, and a means of propulsion, in order to fly.

On a side note: In he books, no one (but Voldy) can fly. The pelikula took some liberties with apparition, I believe, for cinematic effect - i.e. oohh cool! black lights fighting evil black ones!

Cuz... Hes Voldemort. Nuff said.