Ao-2.5rt

[Sprockets]

Re-US-Subs Posting

There seems to be a slight error in attached, as there is no indication on the dwg of the springs acting on the arming weights (Shown in other postings). Items 22 & 26 both refer to the locking springs. Also, there is mention of an Upper Lock for the dispenser container-Is this supposed to be released after the cord tightens, freeing the internal packing/ launching unit from the case? Does anyone have a better solution to the manner in which the two portions "bounce". I think that the package will generally impact at an angle, allowing the upper end portion to be launched skywards. The lower portion will also be moved along the ground by the separation force, tending to roll, being hemispherical, at the same time. The exit gases from the choked orifice will eventually be orientated so as face the ground, simultaneously breaking the lateral travel and launching upwards through the unbalanced thrust. This would account for the reduced height achieved by some of the halves. Shoot me down!

Martin.

 

[Sprockets]

Tarbelin 51- Your picture shows that the rotation producing vanes appear to be attached by threading a strap through a small slot in each cup. Presumably wind force on back of cup would tend to tension band, stopping it slipping around body. Has anyone ever seen vane fixed in this complicated and complex fashion, with perhaps spot-welds, not shown, used as well to make it secure? However, most photographs show vanes spot-welded to band, a much more secure attachment, and a closed band (Ring) can be used. This picture also shows dimples where band has been punched to engage with a depression in end plates mounted in hemispherical bomb ends. The latest versions show that sheared portions of the bands now engage in end plates. Perhaps it was found that the "bounce" produced by the spinning vanes digging into the ground tended to loosen the ring (Reducing bounce), so leading to the use of sheared lugs, in place of dimples, being used?
U.S Subs- translation of the manual states that type 11 has a fuze functioning upon expiry of the "strafe" delay of 1.5 +/-0.7sec
Might "strafe" mean start, and thus signify that the short delay used in the mk 1 is followed by the longer delay.
Perhaps originally, after the body bounced, the two halves separated and were timed to explode with the short delay. It was then found that sometimes a half would hit the ground and roll until it stopped with the flat side in ground contact. The delay column now was provided with a choked portion (States in info to ensure delay stays intact?), so producing enough thrust to project the portion skywards, detonating after 1.5sec. Any comment? Perhaps this is how the second version differs?
The same manual omits the springs operating on the two safety retainers. Normally, just these two retainers would be sufficient to prevent transit shocks releasing them, but the two retaining caps, housed in the bores of the locking pins, could cause problems if shocks time-separated would cause first one and then the other retainer to lock out. The "Pantograph" prevents this, as movement of the retainers can only take place through an outwardly, simultaneously directed, radial force. The locking pins must be an interference fit in the retainers, so the note that additional safety is secured by the springs acting against the locking pins, in turn pressing the retainers against the (plastic) plate between retainers and pantograph, can only be correct if the plastic plate can move and produce internal friction in the pantograph.
Finally, no mention is made of possibly a shear pin mounted above the Left Hand guiding pin in picture 9.(Or is it a ball?) A You Tube
video of a guerrilla dismantling one of these has him pointing to this shear pin and explaining its importance, in Arabic, unfortunately! Perhaps it was found that vibration of the rotating munition could cause premature firing of the primer, despite the springs, hence this shearpin or ball? Perhaps Joop (M T M) can cast an eye over his sample and answer some of these queries?

An excellent example of Russian design-achieving a complex effect with the very minimum of parts!
Martin.

 

[Sprockets]

A few more points.A) The first time-0.1 to 0.35 s might represent the interval from igniting the fuse-train in each half to the point at which the vented gas increases its expulsion rate to produce a lifting effect, when the so-called "Strafe" delay of 1.5 sec starts, ending in detonation.
B)-As the strikers operate on the "Allways" principle, action of the stab primer might be slower than the return of the safety retainers, as the munition slows its rate of spin on ground impact, hence the need for the locking pins.
C)- What I thought was a shear pin mounted in a striker weight is instead perhaps a hole, which registers with a similar hole in the baseplate. Perhaps a temporary location pin is used during assembly, to ensure that the safey retainers engage properly with the striker
weights, which are held in a fixed location?
D)-Finally, it would appear that the band carrying the rotation cups was originally wider, and just jammed on the tapered inner portions of the hemispheres. It was found that the band had additionally to be secured by punch marks into recesses in the two hemispheres.
The new band now fits in a space left between the two hemispheres, and a lug engages with a recess in a hemisphere. There is also a pad inside each half, possibly resilient to minimise breakup of the cast explosive on impact.(Catering for expansion of explosive with heat from the lifting jet as well?)
Phew!
Martin.