Requirements
Hard Requirement: Air Dash

On it's own the mod only replaces the Whirlwind Sprint effect, to use mid-air another mod such as CGO Stripped (recommended), Unofficial Character Behaviours Enhanced Patch SE or Mid Air Shouts - Shout while falling is required

Recommended
Better Jumping - for sprint jumps. Also recommended to configure the text file to give yourself a little more jump height so you can dash further and clear low obstacles.
Sprint Sneak Movement Speed Fix - fixes movement speed slowing down when sprinting and shouting
True Directional Movement - HIGHLY recommended. Adds momentum after dashing mid-air. Also have a look over the mcm settings such as "face crosshair when shouting" to get a setup you like.

Compatibility
Load after mods which change the Vanilla Whirlwind Sprint Shout.
Compatible with Shout Animation and Sound replacers.
Since this mod changes the Spells assigned to the Whirlwind Sprint Shout, other mods which affect Whirlwind Sprint such as Whirlwind Sprint Redone and Whirlwind Sprint FX Removed won't have any effect. I'll probably put out some more patches and variations in the future.
Compatible with Thunderchild.
Stormcrown patch from Hurlocks available here.
This mod changes the spells assigned to the word slots of the Whirlwind Sprint shout. The original whirlwind sprint spell effects are left untouched and unused if needed for whatever reason.


If using with Mid Air Shouts - Shout while falling by hesmick download the required patch included in optional files.

If using Better Third Person Selection add "air walk" to Better Third Person Selection\MCM\config\BetterThirdPersonSelection\ObjectFilterList.toml as shown:
ignore = [
"air walk",
]

This prevents the activation prompt for the invisible platform from appearing when dashing.

Instructions for Use
Currently two versions are included, one with the original "explosion" staggering effect (edited to be non-hostile) from Air Dash and one without. Use only one version and load after Air Dash.esp.
Both versions have a fall damage immunity effect which goes from 3 to 5 to 9 seconds (the effect is required so you don't immediately die after pressing the button) so you can zoom around without too much danger. :)

Safe to flag as esl - just make sure to compact formids and flag Air Dash at the same time.

From testing:
With CGO Stripped:
+Shout while jumping or falling at the push of a button, sheathed or unsheathed. It just works *** . The recommended setup.
+Visuals and sound effects play normally.[1]
+Can begin holding Z on the ground, jump, and release the shout while in the air.
-CGO's Animation blending and upper/lower body separation can make your animations look weird and different behaviour mod setups might break functionality in certain situations.[2]
1. The visual FX don't show when used in quick succession and the voice FX when using more than one word might sometimes be delayed (vanilla bugs).
2. Behaviour mods which overlap with CGO such as Jump Behaviour Overhaul or Paragliding might cause unwanted behaviour e.g. Paragliding seems to stop the jump shout from working with weapons sheathed in 3rd person. YMMV.
Turn 1st Person Leaning to 0 in the MCM to stop the camera bobbing downwards when using Whirlwind Sprint.

With Mid Air Shouts:
-Visuals and sound effects will not play properly in the air.
-Also script based, the two mods can play buggy together (for example, grounded whirlwind sprint can lose SFX temporarily). Tries to proc twice with very low shoutrecoverymult. Read the original mod page for more info.
+Not a behaviour mod, so no other requirements or incompatibilities.

The patch in optional files is required to reenable the use of Whirlwind Sprint with Mid Air Shouts' script.

A Note on Jumping Attack
NickNak's Jump Attack (give a dog a bone) has some shout functionality (which already works with vanilla whirlwind sprint) but it's a bit finicky.
Shouting works mid-air but only with weapons unsheathed and:

• You are wielding a bow or spell in right hand.
• If using a melee weapon, pressing Z while left or right clicking or clicking immediately after.
  

If you prefer Jumping Attack's changes to 3rd person combat but want more shout functionality you could try deleting the _1stPerson folder in Jumping Attack/Nemesis_Engine/mod/jpatka and the 0_master folder in CGO Stripped/Nemesis_Engine/mod/dscgo, which will keep CGO's jumping attacks and more functional jumping shouts in 1st person while removing it's changes in 3rd person. Remember to re-run Nemesis.
(As it stands this is probably the best setup for a balance between functionality and compatibility IMO.)
 
Other Issues
With some air attack mods WW sprint is influenced by the camera, somewhat. You won't gain height but if you look straight down you won't move and if you look ahead or up you will move further. Sometimes when shouting while falling with the camera pointed downwards you may collide with the invisible platform and come to a halt.
Functionality with Mid Air Shouts - Shouting While Falling is markedly jankier than with the behaviour based air attack mods. You will definitely feel it more if your modded build lets you fire off shout after shout like King Wulfharth but hopefully for normal gameplay it strikes a good balance.
At the end of the day all this mod does is replace spell effects with someone else's mod. I'm not really experienced enough to help with advanced troubleshooting especially re papyrus and behaviours but I can try and give suggestions. I'm uploading the mod for anyone prepared to have it in their game as-is or for anyone who wants to help to implement the fix in a better way.

Credits
JamesDogg for the original Air Dash mod
Gameplay captured on the Keizaal modlist by TateTaylor and The Vanilla Enb Two by michaelfoushee
Three-Eyed Swallow armour by 4thUnknown, HDT patch by taturutia

This is my first mod release and very much a quick and dirty solution. Hopefully (as JamesDogg says) someone might be able to implement this in a more modern and compatible way. :)