Tunnel clearing operations using the Mighty Mite blower

The Mighty Mite portable blower when properly used in conjunction with smoke pots or smoke grenades would force the smoke throughout a tunnel system and generally reveal the entrances and vents, if any were present.

The Mighty Mite was an agricultural backpack spray-duster. It was powered by a two-cycle gasoline engine, weighed 25-lbs (without fuel or agent) and displaced 450-cubic feet of air per minute. The fuel tank held approximately one quart of gasoline-oil mixture which would permit operation in excess of 30-minutes. It was equipped with a two foot long flexible tube that had a metal nozzle on the end. The Mighty Mite had a polyethylene agent tank which could be filled with either 10-lbs of powder agent or 3-gallons of liquid agent.

The Mighty Mite portable blower could be used to;

• Force the evacuation of unmasked personnel from a tunnel system using smoke or riot control munitions
• Locate vents and entrances of a tunnel system using smoke munitions
• Generate an agent cloud for use against unmasked personnel in the open using a powder agent

The first tactical employment of Mighty Mite was during a search and destroy operation conducted by 8th Infantry Regiment (ARVN), 5th Division, in III Corps Tactical Zone that took place 8th -11th October 1965.

The objective area selected was the Iron Triangle which was known to contain many VC tunnel systems. The US Chemical Advisor to III Corps participated in planning the operation, and proposed the use of Mighty Mite.

The III Corps Chemical Advisor contacted the ARVN 5th Infantry Division Chemical Team Leader and coordinated the time and location for organising and training a tunnel tracing and flushing team. On 7th October 1965 a team was organised from the Division Chemical Team (see opposite)

Training for the newly organised tunnel tracing and flushing team included operation and maintenance of the portable blower, and practical exercises in operation of the blower with smoke. The team also prepared for the operation by cutting a five gallon can in half. A hole the size of the blower nozzle was cut in the upper half to facilitate blowing smoke into vertical entrances of tunnels. It was planned to use the lower half to block tunnel entrances (see Figure 1).

Initial plans for employment of the tunnel tracing and flushing team called for it to initially remain with the 8th Regiment CP and respond to requests from the attacking battalions. However, this plan was later amended to place the team and an engineer platoon in direct support of one of the attacking battalions for each day of the operation. This method of employment insured that the tunnel tracing and flushing team could respond rapidly to requests, and the engineer platoon could promptly destroy the tunnel system after it was traced and flushed.

A tunnel was discovered on the first day of the search and destroy operation by the 2nd Battalion, 8th Infantry Regt. The area surrounding the tunnel was secured by the 2nd Bn while the tunnel tracing and flushing team went into action. The techniques which they employed were as follows;

1. The Mighty Mite blower was placed near the tunnel entrance and a poncho was spread over the horizontal aperture. The hose nozzle was placed through the head opening of the poncho and the hood strings were fastened tightly around the hose nozzle. Earth was placed around the edges of the poncho to form a good seal (see Figure 2).
2. The lower half of the five-gallon can was inserted in another tunnel entrance which was a few feet away from the original entrance to prevent the smoke from dissipating before penetrating all portions of the tunnel system.
3. One corner of the poncho was raised and a smoke grenade was placed in the tunnel (approximately three feet away from the poncho to prevent burning it). At this time the Mighty Mite blower was started. A smoke grenade was used initially so that if the tunnel was small an entire smoke-pot would not have been expended. Further, the 10-lb smoke-pot burns approximately eight minutes while the smoke grenade burns for two minutes.
4. 2nd Battalion troops moved out in all directions (360-degrees) from the blower while smoke munitions were continuously placed into the tunnel entrance. The troops detected smoke escaping from tunnel vents and entrances, and were on the look out for escaping VC. However, no VC were discovered in this particular tunnel system. As vents and entrances were detected, the apertures were marked and sealed.
5. When it was determined that all entrances and vents of the tunnel system had been detected and the tunnel trace was apparent, further smoke munitions were unnecessary. However, the blower was left running until all smoke had been cleared from the tunnel system.
6. The engineers then searched through the tunnel system for possible asphyxiated VC, booby traps, weapons, equipment and supplies. Once this had been accomplished, the engineer unit set the charges and destroyed the tunnel system.

This experience with the Mighty Mite blower was successful and established that the blower could be used to trace tunnel systems. It should be pointed out that, although only HC smoke was used with the blower on this operation, the use of riot control munitions employed either singly or in combination with HC smoke could also be very effective in flushing VC from tunnels.

The principles of operation and employment of the Mighty Mite portable blower were learned quickly and easily by members of the 5th Inf Div (ARVN) Chemical Team.

• Plans for search and destroy operations using the Mighty Mite team had to allow sufficient time for proper tunnel tracing and flushing.
• The tunnel tracing and flushing team was most effectively employed when attached to infantry maneuver units. If the team stayed at a rear location with the headquarters or reserve unit, time was lost and security for movement to the tunnel site was limited. In addition, the team enjoyed relatively good security with the infantry maneuver element.
• Both smoke grenades and smoke-pots were taken with the team on an operation. Smoke resources could be conserved by using a smoke grenade for initial tunnel tracing.
• Extra fuel for the blower had to be taken with the team because the blower's fuel tank capacity was only one quart. Teams determined fuel requirements by totaling the burning times of all smoke munitions (smoke-pot = 8 min; smoke grenade = 2 min).
• The upper and lower halves of a five-gallon can were effective field expedients. The lower half was used to seal any nearby tunnel entrances and prevent dissipation of the smoke. A hole the size of the Mighty Mite blower nozzle would be cut in the center of the upper half. Employing this half with the blower simplified blowing smoke into vertical tunnel entrances. The poncho when tied securely around the blower nozzle was effective on horizontal entrances to tunnels.
• The Vietnamese soldier was quite capable of carrying the 25-pound blower for extended operations. Further, the desirable smoke munitions load for the ARVN munitions bearer was three smoke-pots and five smoke grenades.