Twisted Flechettes

I recently acquire a small collection which included a few flechettes - with and without sabots – mostly from the U.S. SPIW and ACR programs. Being almost completely ignorant of such projectiles (alas, they were never loaded in the .450 Short Revolver cartridge) I was surprised to discover, thanks to Paul Smith, that the normal flechettes were designed to provide a left-hand twist. On two of the saboted flechettes, the previous owner had written “L.H.” and “R.H.”. Apparently, the right-hand twist flechettes are quite rare and Paul suggested “end-on” photographs of the tails which shows the difference.

Twisted Tails 1

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Very interesting, thank you for sharing. It is the first time I see both directions of twist mentioned in connection with flechettes.
As a matter of fact, the drawings in “SPIW: The Deadliest Weapon That Never Was” mostly show fins set up for right hand twist (if they show cant at all).
In any case, this very slow twist is intended not for stabilization, but for compensation of asymmetries. Youtube videos of Honest John or Lance missiles at launch show application of the same principle in an impressive way. These fin-stabilized missiles use small rockets to make them spin.

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Chris,

Thanks for mentioning this. Here’s a cut from HWS Vol. III, CH 11, pp 314:

image

Note the reference to Left and Right canted fins. FYI, all of the Dardick/H&R triplex SPIW flechettes I can see the fins of have a LH twist. At velocities of 4,700 fps, it wouldn’t take much of a cant to really spin them up. It’s interesting to read that the weapon(s) that fired these had a muzzle attachment to shred the puller sabots as they emerged and to create spin.

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An AAI flechette draw set.
Adding perhaps to flechette lore, these are all left cant.
From left to right using 1065 wire
Point wire
Plate
Stamp fins
Unplate and heat treat.
Grind diameter and point,
Grit blast. (for scale this is 1.643" long)
Now it’s easier to understand why these were so expensive to make. And don’t ask why the plate and unplate as I don’t know. But perhaps someone does know?
AAI flechette draw set

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As you would know…they were eventually sand blasted so the departing sabot would grip the flechette and not “forget” to take it with it down the barrel particularly with the 5.56 varieties

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