Pom-1s

[Sprockets]

This WAAPM is obviously derived from the US BLU-42B, a fact which its designer, A.Popov, freely admits on his website-http://a-popov.livejournal.com/104592.html However, it is completly different internally, and also has an additional external safety, released by a pull wire when dispensed. Perhaps it does not use auto-rotation for arming, so it can be dispensed close to the ground for a greater density of coverage? Also it seems to use a hydraulic timer for arming, and a mysterious pyrotechnic lock connected with the external safety, in some mysterious fashion.

Other differences are serrated ground engaging discs at the end of the trip-lines-perhaps the rather smaller ball anti-disturbance switch needed a stronger pull than the BLU- 42B? & separable spider-heads, so presumably to allow the shafts to remain in position, sealing against water ingress. If the battery is a reserve type(Probably) then perhaps the Pyrotechnic Lock is to provide enough force to release a strongly sprung striker, so crushing the electrolyte reservoir, as well as the hydraulic dashpot or sequence timer.

Is there a fully sectioned view, as the Ordata image suggests, or perhaps Mr. A Popov might oblige! Someone must have a sectioned item, or a description of the action.

Many thanks in advance,

Martin.

 

[weberoed]

POM 1
IDENTIFICATION.
a. (U) Type. The POM-1 and POM-1S are ground- or aircraft-dispensed, scatterable, electro- and hydromechanically armed, antidisturbance, antipersonnel (apers)landmines. The POM-1S also incorporates a self-destruct feature. Both mines deploy eight 6.00-meter (19.69-feet)-long tripwires. The POM-1 and POM-1S are identical in external appearance.

DESCRIPTION.
a. (U) Material. The mines bodies are steel.
b. (U) Weight. The mines weigh 750 grams (1.65 pounds) each.
3. (U) HAZARDOUS COMPONENTS. The main explosive charge weighs 100 grams (3.5 ounces) of an unknown composition. The pyrotechnic lock and fuze detonators are of an unknown weights and compositions.

FUNCTIONING.
a. (U) Arming. As the mines are ejected from the dispenser module, pyrotechnic locks ignite, safety pins are withdrawn (safety pins are part of module), and mechanical locks are released. When the pyrotechnic mixture has burned, the safety rod is pushed outward by a spring, ejecting the mechanical lock, clearing a path for the remote arming mechanism (MDV). The MDV housing is then moved by a compressed spring, slowly overcoming the resistance of the liquid silicon (not shown) surrounding it. The arming time varies from 1 to 10 minutes depending on ambient temperature.
After half of the arming time has elapsed, the MDV housing has moved far enough to release an electrical contact lock, which enables part of the electrical circuit and begins to charge the capacitor. When the arming time expires, the MDV housing closes an electrical contact, releasing power to the pyrotechnic pusher allowing a shutter to turn, cutting the shutter pin. At this point, the tiltball switch is armed, but the tiltball is prevented from making electrical contact. The lockballs holding the X-shaped covers drop into cavities in the shutter, allowing the X-shaped covers to be ejected as springs under each tripwire drum expel the drums outward. The tripwires unwrap as the drums travel through the air.
b. (U) Firing. At this point the mine capacitor is fully charged and the tripwires are deployed. Any movement of the mine or pulling of the tripwires tilts the mine body allowing a tiltball to touch electrical contacts.
The tiltball, making electrical contact, closes a circuit allowing the capacitor to discharge to the detonator, initiating the explosive train. The POM-1S mine will self-destruct following a delay of 1 to 40 hours if it has not been disturbed. Operational life of a deployed POM-1 mine is from 5 to 15 days. Lethal radius of the mine is 4.00 meters (13.12 feet).

 

[Sprockets]

Thanks, Weberoed, for the information about the functioning, which gave previously unknown details. It states that safeties include withdrawal of a safety pin, pyrotechnic lock and removal of a mechanical lock.(I suppose this means that the cross-shaped retainers for the spring-loaded line ejectors are obstructed when in the dispenser by packing?)

As for the Pyrotechnic Lock, I have only just realised that a fuse-train in the dispenser flashed through a hole in the outer part of the lock (Passing around the safety pin, which is still not released at this point), so igniting a slow-burning compound, which eventually allows a spring to withdraw the lock on the hydraulic dashpot (MDV). If it burnt slowly enough, it could only release the dashpot after impact on the ground. Then the initial closure of contacts, though the dashpot releasing the ball-lock shown, would charge the capacitor, and possibly remove a lock on the ring. Further movement of the MDV would close contacts to fire the pusher(Dimple unit), rotating the ring to shear a pin and freeing the cross-retainer ball-locks. The lines are then ejected.

The plunger which engages the contacts connected to the capacitor probably simultaneously disengages from a hole in the ring.Thus firing of the pusher by heat or stray EMF would fail to move the ring, which would remain bolted. Similarly, should the dispenser be subjected to heat, the pyrotechnic lock could not activate the unit, as the safety wire would be in position. I am not sure how heat could be prevented from firing the ejection cap, which would then operate the ejector charge, and the submunitions then be armed?

It is then stated that the tilt-ball switch is armed, but the tilt-ball cannot make contact. Is this correct, as there doesn't seem to be a lock for the switch? Could the MDV unit close an additional switch? Does anyone have a picture showing the dashpot(MDV) construction, as this is the heart of the device, and also if the battery is of a reserve type? Further, was the MDV unit additionally used to neutralise the unit after a longer period?

It is most unusual that the unit was not centrifugally armed, especially as it has already vanes to spin it to widen distribution. Could a pyrotechnic lock be used to ensure that it would still function if the helicopter dropped it close to the ground. Could 'copter downwash lead to premature arming if spin was used?
. However, I don't see how, as mentioned above, the weapon could ever be made fully safe against a ground fire involving the launching craft!

Another unusual feature is that the plungers retaining the cross-plates only move a short distance, before the cross-plates disconnect. Probably this is to ensure that the mine stays water-tight, as the plungers continue to block the holes.

As this submunition was designed by the nimble mind of A. Popov, perhaps this query could be brought to the attention of his website, perhaps by a Russian speaking member of the forum? Incidentally, he obviously has a high regard for the excellent Russian Ordnance site, Sapera.ru, as he mentions it in his website. If anyone has yet to visit it, don't delay, because you don't know what you are missing! Even if not everything has been translated into English, the diagrams are fantastic, and often self-explanatory.

Thanks in advance for any further information on this submunition.

Martin.

 

[Sprockets]

Following close inspection of Ivashkin's excellent site, www.saper.etel.ru/mines-2/pom-1.html, there is a totally different explanation of what happens on ejection form the dispenser. After the ignited pyrotechnic lock burns out, a spring operates to retract a locking pin from a central spindle, so allowing centrifugal force, developed as a result of auto-rotation, to move the silicone fluid-damped(MDV) central spindle against the spring, and close contacts(Not shown) to charge the capacitor and supply current to the anti-dist. sw. Somehow this also releases the small ball lock securing the shutter ring, allowing turning of the shutter plate, releasing the crosses (2)(Balls drop into holes in plate) and allowing the spring loaded anchors, assisted by the centrifugal force, to extend while the sub is still spinning in the air. Only after the munition lands and stops spinning, does the spring on the MDV unit re-exert itself and return the heavily damped central spindle back to its initial position (Where it was previously locked by the pin extending from the pyrotechnic lock) and beyond, allowing the electrical contact lock to shut and connect the current-interruption sensor electronic circuit output to the detonator. As it is fitted with a normal battery, eventually this will become discharged, unless the bomblet is fitted with an electonic timer to sterilise it. This is completly different from the US BLU42, which ejects the trip-lines when stationary on the ground.
This difference in operation could be explained because the BLU 42 was meant for a jungle environment, so trip-lines already deployed would become entangled in the jungle canopy. Instead, an impact sensor deploys the trip-lines many minutes after operation, so that even if initial impact is made against a branch, there is still plenty of time for the unit to gradually fall to the ground, passing through dense vegetation on the way down. However, ground deployment has several disadvantages-A)-Possibly only half the lines will avoid impacting the ground adjacent to the device B)-The anchors will not bury into the ground, so that it is more likely to slide along the ground when the enemy comes into contact with a line. This perhaps explains why the US type has a very large diameter & sensitive anti-disturbance switch, compared to the tiny Russian switch. The Russian anchors also have serrated discs to assist ground burial. The centrifugal force on the trip lines will ensure full deployment, even if a strong wind is blowing. Since the retaining stars for the anchors have to be ejected during spinning, this may explain why the end portions become disconnected during ejection, as wind force may tend to cause the spindles to jam, should they be in one piece. Thus the Russian device, in the original non-sterilising form, had only need of one electronic board to sense current interruption in the anti-disturbance switch. Ivashkin remarks that the battery was not at its best in cold weather, which is why probably a capacitor was used. All in all, a much simpler internal structure than the BLU42, and deploying more of its trip-lines in a non-jungle situation.

The main worry about this scenario is whether it would be such a good idea to have the trip lines whirling in the air, and tangling with adjoining bomblets, and becoming tangled when the munition hit the ground and stopped rotating quickly. If the explanation posted by eodtec was modified slightly to bring it more in line with Ivashkin, but deploying on the ground, then, after the pyrotechnic lock had released, centrifugal force would prevent the MDV unit moving. Only after spinning stopped on ground impact, would the MDV plunger be free to slowly move. First it would release the electrical contact lock, allowing the capacitor to commence to charge,as well as supply current to the anti-disturbance switch and also release a ball lock, just visible, to free the arming shutter. The ball-locks securing the X-retainers for the anchors would release & allow the anchors to eject as previously. Further travel of the MDV would trip another switch ( not seen) to connect the detonator to the output of the no-current flow electronic sensor for the anti-disturbance switch, which would allow the capacitor to discharge on sensing no current. However, there is considerable divergence between Weberoed and Ivashkins scenarios, to whom, as well as pzgr40, I am most grateful. Any suggestion or criticisms of my explanations, and as to why there appears to be this divergence in explanation ? Ivashkin notes quantities of the POM-1s were not large, and it remained unknown to most troops. Perhaps this explains the varying descriptions of its operation, as perhaps none were ever physically examined by EOD .

Any experts care to comment?

Martin.

 

[Poroch]

Hi Martin,
I am not a "big expert" in ussr after WWII munitions, but I have some info, so info on www.saper.etel.ru not complited - on pictures you may see detail #14 its moved from liquid caoutchouc and after some time relies balls #10 and it relisted the X-retainers.



And release & allow the anchors takes place already on the ground.
After a while I am ready make a accurate translation of the POM-1 S instructions.


WBR,
Poroch

 

[weberoed]

Poroch
would really like to see the translation of the POM-1S. thank you in advance

Mike

 

[EOD]

 

[frogman]

Hi, very nice set of pictures and text. EOD, may I ask what was the source for the last post? I am trying to get my head around the electronics mechanism of the tilt switch on page 23. Do you understand any of it? electronic symbols seem strange. What are зпн; зпт; and зд ? I'd really appreciate if you'd help. For some reasons it is very satisfying when I understand a fuze mechanism. Thanks

 

[sgdbdr]

Hi


Found just now on internet, photos of the cluster pictured in the last image of EOD's post.



Regards,

S.

 

[frogman]

This is a diagram for tilt ball switch of POM-1S. A is plastic container, B is a metallic ring with metallic tilt ball inside and C are two metallic rings. Regardless of what position the mine lands, B is going to make a contact with C. This 'make and break' contact action doesn't matter during the arming delay period. But, after the expiration of arming delay, any movement of mine causes the contact between B and C to break momentarilly and the sensing electronics detect the current interruption and send a signal to a transistor or SCR which open the patch for discharging of firing capacitor to detonator. I'd really like to see sensing electronic diagram for POM-1S or BLU-42B, but there is no publication that I can find. One curious collector could easily trace the components and produce a diagram though, if he is inclined.

 

[Ivashkin]

This is a diagram for tilt ball switch of POM-1S. A is plastic container, B is a metallic ring with metallic tilt ball inside and C are two metallic rings. Regardless of what position the mine lands, B is going to make a contact with C. This 'make and break' contact action doesn't matter during the arming delay period. But, after the expiration of arming delay, any movement of mine causes the contact between B and C to break momentarilly and the sensing electronics detect the current interruption and send a signal to a transistor or SCR which open the patch for discharging of firing capacitor to detonator. I'd really like to see sensing electronic diagram for POM-1S or BLU-42B, but there is no publication that I can find. One curious collector could easily trace the components and produce a diagram though, if he is inclined.

I have manual for BKF-POM-1S. Made for Air Forces.

 

[frogman]

I have manual for BKF-POM-1S. Made for Air Forces.

Does that include electronic diagrams? They are very hard to come by. I am looking for electronic diagrams of POM-1, МВЭ-92, and МВЭ-72. I think the only way is to draw them manually from the deactivated items. I have made one for type 72b AP mine. It's not really hard as they contain few components.

 

[Sprockets]

Frogman-sorry about delay. The "fleeting Contact" anti-disturbance ball switches used in the POM-1S and BLU-42/B work in a slightly different way to your surmise. They are designed, after the weapon comes to rest, to have the ball come to rest in a depression in the track, where it does not close the circuit. Only upon movement is the ball dislodged from the stable position, and then makes contact, before rolling into the next depression. However, contact has been made. Thus there is no need for a transistor. U S patent 3372253 has a good exposition of one design, which looks very like the BLU-42/B. Earlier fleeting contact switches were sometimes of the mercury type, where a small amount of mercury, in passing through a narrow constriction, bridged contacts at the point. However, the mercury could not remain at this point, as the constriction had tapered lead-ins and outs. A Vickers patent in the twenties just used a pendulum, accepting that the device might sometimes explode on ground contact!

 

[Sprockets]

A point about the device that has puzzled me is the "Pyrotechnic Lock", combined with a safety wire. This Pyro lock has an advantage over the use of spin to arm, as a fast moving plane would cause it to arm more rapidly, whereas the pyr lock is purely time. A flash tube from the dispenser lights the pyrotechnic pellet before the ejection charge functions, so that it is still burning after the safety pin is extracted. The munition is prevented from activation while it might be jostled by other subs. When the blowing part of the pyro pellet is reached, the metallic sleeve containing the pellet is ejected (I think the end of same may be split and expanded, to ensure it grips the bore strongly in which it is housed.) If the safety pin should be in position, the blowing charge cannot eject the sleeve, so the pressure exits via the ignition hole, and the device remains inactive.

If a stored container should be in a dump fire, being made of plastic, the pyro pellet is probably likely to be ignited before the ejection charge ignites, as this is well insulated in two metallic castings? Thus, the pyro may have burnt out, igniting the blowing charge before the safety wire is ejected, so no arming again takes place. Has anybody any other thoughts-no mention of the exact functioning of this lock is available! I am not too convinced by this argument! Perhaps, but unlikely, that safety for a Dump Fire could be relaxed, due to the small size of the explosions!
I am pretty sure that this weapon uses an electrochemical timer, as did the U S BLU 42A (On the Drawings, there is a canister which is not identified) I think that the trip-line spools are mounted in the base of the cups housing the trip-line ejectors, but the US version appears to mount the spool in the ejected cap.
Who disagrees?
Martin.

 

[Sprockets]

Latest update-please disregard musings previously sent! I have now learnt that the device differed from its US progenitor in not only not using centrifugal force to arm same (A pyrotechnic lock being used. which probably led to a more compact fuze assembly), but the weights attached to the trip-lines were released during its descent to ground. This meant that centrifugal force helped to extend the lines, so ensuring full deployment, whereas the BLU42B, extending after impact, might well find some of the weights directed into the ground! The Russian design uses serrated discs on the weights, which would dig in on ground impact, so stopping rapidly the whirling motion, and helping to ensure the line remained taut.

The fact that the X-shaped retainers detached themselves from the support rods on the POM could be to ensure that the air drag on the supports might otherwise have prevented full ejection of the retainers-the US sub would not have this to contend with, as it was stationary at release. Also, the Russians appear to have placed the line spool in the bottom of the well mounted in the body. This would avoid line being tangled by the slipstream during the descent. It made sense for the US version to mount the spool on the weight, so adding its mass to that of the weight itself.

Probably America, in view of its use in Vietnam, wanted to avoid the triplines becoming caught in jungle canopy, so voted for ground launch.

The POM-1s, I think, used a hydraulic, silicone fluid timer, with all its innaccuracy with varying ambient temperature, as the more accurate US electrica E-C timer would have been more costly, and also would drain the battery, life of which was a major problem for the POM-1s. Also, the Russians used a fleeting contact disturbance sensor, as opposed to the BLU-42 having an intemittent contact sensor, reguiring attendent electronic circuitry, and a small continuous current drain. It would be a more sensitive switch, though! (Birdman-I was incorrect when I stated that the BLU-42B used a fleeting contact switch-my apoologies! The circuit diagram of the US munition would be the one that would be of interest to you. The drawing of the switch for the POM-1s is incorrect, a ball with a projecting rim not being used, but a misinterpretation of a drawing)

I hope that no-one disagrees on any of these points. If agreed, I will then reference the positions of the actual internal switches, tieing in with the circuit diagram that EOD supplied.

Martin Cummins.