The author makes no claim to any of the original intellectual property associated with the Naruto universe, but humbly seeks to add to the appreciation of the application of physics within this and other premises for alternate forms of reality be they mystical, scientific, or any combination thereof.
A frank and honest analysis of the physics underlying the technique and its current variations.
To begin it should be noted that Naruto Uzumaki, in his own awkward cobbled together way, has performed the Grand spiral technique at a level of mastery without peer. No one was ever as good with the Rasengan as he was, period. Not Jiraiya. Not the Yodaime Hokage. He was it. Only he could even begin to use the wind release variations, and he needed help from his clones.
This was because the Rasengan was such a difficult technique to master. The first stage is simple enough; all you do is pour chakra into a balloon, then use it to spin the water until it pops. Naruto, instead of learning the control needed to do this strait, had instead decided to generate the necessary turbulence with his unused hand as an expedient, moving it rapidly and randomly around the outside to generate turbulence. And it worked.
The second step was to ramp up the power until you could pop a rubber ball. This requires you concentrate to the point of nearly shredding you chakra coils until you become properly conditioned, and with Naruto's control was all but impossible. By concentrating all of the energy his body could muster upon a single point in his palm, he was ably to get the proper concentration of chakra within the spiral to burst the ball. If used on someone, this would cause middling serious surface damage but nothing that would cripple or kill.
The third and final step required the creation of a sphere of chakra to contain the turbulent spinning force of the attack. This he did by using his own hand to stabilize the energy, and the clone's two to push it to speed and contain it. When you slammed this completed Rasengan it into someone, their organs got feng shui'd and they were hurled through the air as all the kinetic energy of the spiral was released inside of the body. It was almost always a knock out punch, if not fatal. And that was in a nutshell, the Rasengan as Naruto learned it.
But the technique got exponentially harder from there as you tried to add an elemental affinity.
First, of coarse, you actually had to be able to use the nameless, instinctive jutsu that don't require hand seals. Techniques that were never farther away than the earth, air, or water, or else could be generated from the user's body directly. Learning to use his air affinity was a major pain in the ass, simply because he had never done a jutsu higher than academy level stuff without hand seals except for the kage bushin. That and the fact that he never knew that he had an elemental affinity before.
Wind wasn't an easy one either. Of all the elemental affinities it was the only one to require such a high level of technical skill. It broke down like this: most elemental techniques were either an ignition of a natural process like fire and lightning using chakra, or else they used chakra to bind matter together to form great honking objects to attack someone with, like water and earth jutsu.
Wind jutsu however, are a mix. It was possible to use chakra to bind air molecules together loosely to create huge gusts, but not terribly profitable as a whole as getting enough power to do physical damage is difficult. Where the wind jutsu come into their own is by using chakra to create blades.
Basically, that consists of pouring energy into the air, then splitting the air into two masses of gas. After that, you accelerate them into each other at high speed on a molecular level, usually while each mass draws in more air from the environment to sustain itself. Between the chakra, the kinetic energy and the friction, the air particles create a very thin, very high-energy patch of air. The air particles being pressed together between the two masses of air are so energetic they'll slice right through molecular bonds without slowing down. It's completely unblockable unless you know the proper chakra techniques. All you have to do is generate the effect in a given direction and you have an attack that flies through the air. There are exceptions and elaborations to these basics, but that's the groundwork.
As if that wasn't difficult enough by itself, the Rasengan has dubious compatibility with wind jutsu. On the surface, they seem fine. Both use air as a medium, both use high-energy air particles to do their job. The Rasengan even looks like a whirlwind. But the Rasengan requires a single unified chaotic energy storm and a confining wall. Wind techniques by definition require at least basic organization and open space to act as an outlet for the techniques, as they could only be sustained with constant airflow.
After god knows how many hours of practice, he finally got enough control over both source techniques to mix them. Judging by the effects observed this is my interpretation of how. Taking the Rasengan as a template, he then tried the first any way he could think of to throw wind effects into it.
Eventually I believe he came across the idea to create two exactly similar Rasengan(s) over top of one another. By creating two, then aligning each stream of chakra so that it impacts its counterpart and generates a wind-blade effect, when it impacts the target it would release all of the knives inside of what it hits. By then modifying the shell so that on impact it reflexes upon the person it hits, you effectively trap the person within a hurricane in glass factory.
The "shuriken" effect was in my observation, either an embellishment or a side effect. The degree of damage caused to Naruto by errant blades that escaped confinement suggests the latter. If that is the case, it is most likely caused by air molecules within the spiral's center expanding due to their energy level and forcing each other out of the jutsu. They form streams at a point of weakness and the spiraling causes them to form into blades, as the same hole in the underlying technique forms multiples holes in the shell at extremely high speed, much like the formation of volcanic island chains by lava pushing up through the earth's crust as it shifts over a single upward stream over time.
The technique required another clone because except for the creation of the shell, it was another Rasengan over top of the first. That meant another two hands of work to generate the spiral and give it proper force. Let alone the additional control demands to hold it together and generate the blades.
The fact that her he has forgone one of the clones is indicative that he is now able to perform a Rasengan single handedly (though that may not be strictly literal). This is mast certainly due to his considerable experience with this high maintenance jutsu.
I have to remind the reader that little of the technical information provided is courtesy of the original material, having been obtained from various fanfictions and Internet references. As such all conclusions are subject to reexamination and should be considered as a hypothesis at best. I beg you indulgence in this matter, as there seems to be little information to be had on the subject of the mechanics of the techniques discussed that has a reputable source, and even fewer that I am able to access.
Thank you for your attention and I hope this exercise has been enlightening and enjoyable
A/N) Originally composed as a technical addition to Stranger Than Fiction; Ch.5., by the author.
Special thanks to Tellemicus Sundance for his work with the Rasengan in general, and the techniques of the Naruto universe as a whole.
Also, with significant response, I will be adding jutsu that are requested, and ones that have peaked my own interest.
These include, but are not limited to:
The three basic academy jutsu
Sexy Jutsu (assumes a significant difference from the henge jutsu, as per fanon)
Elemental Affinities (in depth, with examples form the anime and notes regarding the use of off-element techniques such as ice, wood, ect.)
Summoning Technique (as related to beasts and objets seperately)
Cursed Seal Biomechanics
The nature of Bijuu
Spiritualism in Naruto
As well as any further requests, including fan fiction techniques, so long as the source material is sited. However, it should be noted that none of my conclusions are definitive, merely the best hypothesis I was able to draw.