Feat seen here
5.5 m for height and 28 m for length of the Arwing according to official measurements.
Width measurements are apparently 14 sm (space meters) according to 64 so:
5.5 × 14 × 28
Volume = 2156 m^3
IIRC I remember reading something that implied the Arwings were made of steel.
Steel has a vaporization value of 60117.42 J/cc apparently.
Thus, the energy produced would be 129,613,158,000,000 joules, or 30,978.2882409177837 tons of TNT
As for scaling, as the title clearly states, this was done by a bunch of fodder Aparoids who ganged up on Fox as he tried to make his getaway, and Fox fights hordes of these things on a regular basis and can harm them with his weapons and tank their attacks, but as seen in Adventures, he should totally physically scale as well, given he can physically harm others who can harm him. But if others don't agree that's fine. This is also consistent with Wolf, Star Wolf, and Peppy surviving their Arwings and, in Peppy's case, the Great Fox exploding with them in it as well as the Sniper Rifle being capable of vaporizing other space fighters comparable in size to their Arwings (which Wolf can also tank in multiplayer, albeit barely).
Just to be safe, I'll use aluminum since most spacecraft today are mostly comprised of that.
To recap, the full measurements are:
L = 28 space meters W = 14 space meters H = 5.5 space meters
2156 m^3
Vaporization value for Aluminum is 35190.2 j/cc
That comes out to 75,870,071,200,000 joules, or 18,133.3822179732306 tons of TNT
Though given it says "Overall Height, Width, and Length" it's likely that these numbers are a bit off and it's talking about the entire thing. In that case, divide the end results by like, 3 or 4 and that should be how much overall space the Arwing takes up at worst lol
But I guess if we wanna be somewhat accurate, I'll just try and find the main base of the ship's measurements from the canon measurments of the whole thing.
It's a given the width is pretty much the entire base of the ship as it alone makes up the second longest line for the whole thing assuming the wingspan is the length (it could be accounting for when the wings fold back but eh, even then, 14 sm makes sense as at least a lowball because the wings only take up a small portion of that length and it's likely longer).
So with that assumption, we have 14 sm as the length of the diamond-shaped base. The height and width look to be close and the height is also easy to estimate since only a small portion of the other parts of the ship peak above the main part. I'd wager like, 3.5 sm is a good estimate. And since width and height look pretty much equal we have our dimensions.
14 × 3.5 × 3.5 = 171.5 m^3
That's 10,526,560,242,000 as a low-end using steel values. Still Tier 7, but Low 7-C.
As for Aluminum, the value would be 6,161,804,020,000 joules, so still just barely Low 7-C.
Basically, the only way this gets below Tier 7 is if you deliberately use the metals with the lowest vaporization points, and it'd still be MCB+ even then.
Also, yeah, this isn't totally accurate, I know. Pixel measurements should be used and there is a bit of empty space for the cockpit plus some glass. This was moreso something I did for fun and to also garner more awareness toward the feat so someone with more patience than me can actually perform the precise measurements.
Regardless, even with all that said, I definitely gimped the length of the base part and so the values I ended up getting should, on all accounts, be a lowball. Hell, with the bit of length I missed, that probably could've accounted for the bit of empty space anyways. But yeah, no way this isn't at least 8-A+