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Cuban Missile Crisis 15 Oct to 28 Oct 1962

The note below was written by Capt Bud Hill, RCASC, to Capt Ken Edmonds, RCCS.

Ken, further to our recent conversation here is additional info to supplement data you have regarding Les and the Cuban missile crisis. This was told to me by a member of the US Army Aviation Test Board, two officers come to mind; it was either Lcol Dave Mooney or Lcol Bob Lahay. The force to invade Cuba, if necessary, was assembling in Florida. The concept of using a helicopter as an airborne command and control center was in its infant stage. The only suitable helicopter that could; accommodate the invasion force commander and his essential staff, be fitted with multiple command radios, and have sufficient speed, range and endurance was the UH-1D. In Oct 62 the UH-1D was just coming into service and they were few in number within continental USA. The Test Board’s UH-1D (most likely 6034) was designated to be that helicopter and flown by Test Board pilots; Capt Les Rowbottam (RCASC) was one of the named pilots. Had an invasion actually happened Les could have been piloting the commanding general.

Helicopter Survivability Trials

The US Army Combat Development Command Experimentation Center (UASCDCEC), Fort Ord, California conducted the Army Aircraft Survivability Experiment in 1964. The Experiment’s objectives were to determine under various combat conditions, the time elapsed from first detection by either visual or audio means to the firing of the weapon and, the effects of projectile hits on a helicopter. There were two parts to the trials: acquisition and live firing.

I believe the acquisition phase was conducted at Fort Hunter Ligget, California. Detection points were set up according to the tactical deployment doctrine appropriate to the type of weapon and manned by soldiers from a cross section of active US Army units. Weapons used ranged from the 45 Colt pistol (standard US Army issue in 1964), to crew served weapons, to the main gun on a tank. I believe the tank used was the M48 Patton.

An assortment of different types of helicopters were flown at various ranges emulating typical Vietnam flight profiles. All collected data was synchronized to 1/10 sec through a signal transmitted by a master range clock. At each detection point the weapon/gunner was fitted with sensors that recorded data on the time elapsed from first visual or audio detection, to acquiring the target in the weapon sight’s field of view (FOV), adjustment for leading the target, and trigger action. All captured data was entered on IBM computer punch cards for subsequent analysis by Stanford University scientists. (How many remember punch cards?)

UASCDCEC Project Team IV, Fort Bliss, Texas, conducted the Live Firing phase at White Sands Range, New Mexico. The US Army Aviation Test Board (USAATB) Fort Rucker, Alabama was tasked to provide a CH-47 Chinook and aircrew to do night target towing.

USAAVTB pilots were; Capt Leslie (Les)Rowbottam RCASC – Mission Commander, 1st Lt John Dixon, US Army Signal Corps, 1st Lt Herbert (Herb) Degner, US Army Transportation Corps, and Lt Robert (Bud) Hill RCASC, two crew chiefs (the only name I recall is Spec Ralph Pigg) and a Mr. Ivy ??? the Boeing Tech Rep. The Chinook was used in two sessions, 13 to 28 May, and 14 Jun to 1 Jul, 1964.

The targets were full scale UH-1Bs (without the rotor mast and blades) were designed with a tow cable attachment point on the fuselage’s top, and fitted with lightweight wheels used for moving them by hand. The fuselage had inner and outer skins made of an electrical conducting mesh, which was separated by a layer of non-conducting material. One skin was connected to one side of a battery (+) and; the other skin connected to the other battery (-) terminal. Whenever a projectile or piece of shrapnel penetrated the skins an electrical circuit was completed signifying a hit, which was recorded. Also, external arrays of microphones were on mounts that strategically stood them about 2-3 feet off the outer target skin. The extremely sensitive microphones picked up not only the sound of hits but also near misses. By analyzing the amplitude of the audio signals from each microphone and matching range timing signals, each round’s trajectory towards and past the target could be calculated, and also backward calculated to the specific firing point, the specific round fired, and the soldier who made the shot. All this live fire data was also put on punch cards for analysis by Stanford scientists. By integrating this new data with known weapon characteristics and specific ballistics data, Ph (probability of hit) and Pk (probability of kill) tables could be created. After each tow sortie all hits on the target were repaired so the next flight would have a clean start.

Most weapons that might shoot at helicopters were used in this trial. There were many live firing points used at White Sands. To keep the target within the desired altitude and ground track profile (weapon engagement range and target aspect angle), a dedicated radar system tracked the target and flight corrections were communicated to the Chinook pilots. I was given to believe that Russian/Chinese RPGs and other weapons were also live fired. Profiles included crossing, the weapon/firing point’s front at 90degs, head on towards 0deg, and crossing aspects angles of 30, 45, 60degs.

One senior trial official told me they had as much as 500 tons of assorted ammo for use (which included non US weapons). In one discussion it was pointed out the difficulty a tank gunner encountered. Against tanks, some head on (0deg aspect angel) and 30deg aspect engagements were possible; however larger aspect angles and 90deg crossings were problematic. The problem was the gun sight’s field of view; the gunner could not always acquire the target in the gun sight, track the target, apply target lead and still have the target within the sight’s field of view. Additionally, the turret slew and elevation rates could not keep up with a fast moving target at short ranges.

Chinook 03450 (now in the US Army Aviation Museum, Fort Rucker) was specially modified to tow a target attached to it by 2000 feet of steel cable. The cargo hook (the first Chinooks had just a single hook) was the attachment point but a special guillotine had to be fitted to cut the cable in the event of an emergency. The guillotine from the Chinook’s rescue hoist was removed and fitted to a custom mount around the cargo hook. I have a vague recollection (maybe wrong) that the cargo hook had to be removed and externally mounted further aft for fear that the catenary effect on the cable might allow it to become entangled with the aft landing gear.

Getting the target airborne was a critical part of the task. The target with cable attached was positioned on the ground about 500 feet in front of the Chinook, with the cable S looped back and forth between them. The Chinook took off and climbed all the while keeping aligned along the fore/aft axis of the target on the ground. The pilot was assisted in this climb by the co-pilot, the crew chief watching the cable/target through the cargo hatch and ground spotters. Wind speed and direction could shift throughout the climb. At target lift off the Chinook pilot wanted to be perpendicular in the x, y, and z axis above the target and holding a minimum climb rate of 300 feet per min to avoid the possibility of dragging the target, and to compensate for cable yoyo action (stretch/rebound/stretch) that might allow the target to impact the ground with sufficient force to cause damage or destruction. In daylight with visual reference points it was relatively easy; however, night was a real challenge. White Sands Range is well north of El Paso, Texas and being a live firing range is not populated. Consequently, at night there were no lights nearby and coupled with the San Andres Mountains (5500+ft) bordering the ranges’ west side there were almost no visual cues. Some vehicle and pot lights illuminated the take off/landing pad. While one pilot flew the helicopter and made flight corrections given by the crew chief and ground spotters the other pilot monitored the rate of climb and the fore/aft positioning. Once the target was safely airborne a radar operator controlled the flight to meet the mission’s altitude, airspeed, ground track and range profile for each firing point engagement. Target tracks were planned to pass several firing points on each pass down the range. I am not certain but think the lowest night target track was 200 feet AGL (above ground level). Not one target was totally destroyed, but many target hits were recorded

Recovering the target entailed approaching the landing pad 2200-2300 feet AGL at a walking pace to eliminate the catenary effect, allow for cable stretch, and to minimize the target’s random swinging action. The wind speed and direction at altitude was seldom the same as conditions on the landing pad. Again, lack of visual cues, the need to hover at such height above ground, and because the pilot’s sight distance to cue points were so great it was hard to determine helicopter movement in relation to a fixed point on the ground. As the target ground speed reduced towards 0 descent was initiated to land the target, then the Chinook was flown forward to a point where the cable could be either released without it dropping onto and damaging the target, or with cable still attached, landed about 500 feet to the target’s front.

I’m not certain if it was the first or second deployment the Chinook required sheet metal repairs in the aft pylon. The nearest military facility with an aircraft sheet metal shop was the US Air Force’s Strategic Air Command (SAC), Biggs Air Force Base, El Paso, Texas, home base to the 95th Bomb Wing flying B-52 nuclear bombers. Remember this was just 18 months after the Cuban Missile Crisis. Les went to find the sheet metal shop and arrange repairs to the Chinook. Les entered a hangar where a bomber was being worked on where he encountered an airman and explained the need for a sheet metal tech. The airman indicated that they had to go to another building, and upon stepping out and closing the hangar door, vehicles of armed military police with loaded weapons, a round in the chamber and the safety off, sped around each corner of the hangar. They surrounded Les, asked him to raise his arms, arrested him and took him to the base jail. The combination of a non US military flying suit (Les and I had Canadian Army flying suits); Les’s accent and bushy mustache led someone in the hangar to believe a suspected saboteur was amongst them. To get Les released we had to get a Project Team IV official to identify him to US Air Force officials; I think the officer was Colonel Crisson. Anyone who visited a SAC base in that era can attest to the security attitude that prevailed on their bases.

Near the end of the first deployment we were requested to fly a sick Test Board UH-1A (2086) from El Paso back to Fort Rucker. I recall John Dixon and me giving the huey a basic check. The bird would not hover but considering the altitude (Biggs AFB elevation is 3946 feet above sea level) and the mid afternoon ambient temperature of +8odeg we figured it was a density altitude problem. The next morning with cooler temperatures and a full fuel load we were able get into a hover without difficulty. On 29 May John flew the huey from El Paso to Dallas, while the rest of us went in the Chinook. We all stayed overnight in Dallas and next day, 30 May I flew the huey to Fort Rucker; everyone else went in the Chinook. After arrival at Rucker a complete engine inspection revealed an undetected hole in the combustion chamber, thus the loss of turbine power.

During the second deployment we encountered bad vibrations that originated from the on board auxiliary fuel tank. Attached is my initial draft of an annex to the mission report. In the report PAMI is Page Aircraft Maintenance Incorporated, the company under contract at the USAATB.

The second deployment completed, on 2 Jul, en-route back to Fort Rucker, just passing through the Guadalupe Pass at about 6000 ft. we experienced a SAS (Stability Augmentation System) double hard over. For those not familiar with a SAS think of it as a limited auto pilot system that smooth’s disturbances in the pitch, roll, and yaw axis on the CH-47 Chinook and CH-113 Voyager. A hard over occurs when the SAS applies a non-pilot commanded input to the cyclic system. Pilots were Lt John Dixon and I; Les, Herb, the crew chiefs and Ivy were in the passenger cabin. It started with the nose pitching down 20deg and 90deg left roll. The caution panel lit up like a Christmas tree; I clearly remember No. 1 engine fire warning light on, No. 2 engine EGT (exhaust gas temperature) dropped 200deg, No. 1 SAS disengaged, loss of No. 2 Hydraulic system, and number 1 & 2 generators dropped off line. The cause was a hydraulic leak in the aft pylon and fluid swirling around in the airflow penetrated into electrical connectors. John was piloting at that time and quickly got the Chinook back under control. The Speed Trim was on manual and fully extended; I retracted it as John reduced airspeed. We landed at Wink Texas. There was no shade and with the sun beating on the Chinook it got so hot that anyone working had to wear gloves. The crew chiefs and Ivy found and fixed the problem and we then continued the flight to Fort Rucker 4 Jul 64.

CH-47A Auxiliary Tank Vibration

  1. At various weight and airspeed configurations a heavy frequency vibration occurred in CH-47A, serial number 60-3450.
        The apparent cause of the vibration was the auxiliary fuel tank.
  2. Fuel Tank Description.
    1. Capacity 350 US gal (2275 lbs).
    2. Dry Weight 220 Lbs.
    3. Single cell without baffles.

  3. Tank Installation.
    1. The tank is installed between station 200 and 280 with its CofG at approximately station 240.
    2. The tank is mounted on two wood over rubber runners.
    3. The means of tie down was five cables on each side of the tank attached to three retaining bands.

  4. The first instance of vibration was during a night recovery of a target under the following conditions. (See Form 365F, No 1)
    1. Airspeed approximately 35K.
    2. Weight of fuel in the auxiliary tank estimated at half full (175 gal) 1137 lbs.

  5. The vibration, and blurring of the instrument panel, continued throughout the descent to landing. During the descent airspeeds up to 100k and rates of sink between 200 to 700 feet per Minute were tried in attempts to find the best flying conditions. The vibrations intensity did not appear to change throughout the above flight range.

  6. After landing, a ground inspection revealed that the aft retaining band on the auxiliary fuel tank was cracked at the 135° bend.

  7. As a temporary fix, two nylon tie-down straps were placed across the aft end of the tank. The aircraft was test flown and found satisfactory.

  8. The second occurrence of the vibration was during a daylight recovery under the same conditions as the first instance. Airspeed and rate of sink were again varied without any success in reducing the vibration level.

  9. As a fix, the sheet metal shop at Biggs AFB repaired the aft retaining band with a stainless steel bracket. At this time, three bolts were replaced.

  10. The third incident of vibration occurred during level flight under the following conditions. (See Form 365F, No 2)
    1. Auxiliary tank full.
    2. 1600 lbs of parts, tools and baggage.
    3. 6 passengers.
    4. Airspeed above 80k.
    5. All settings of speed trim.

  11. The vibration level decreased with the level of fuel in the auxiliary tank. Once the tank was emptied, speed up to 120k with the speed trim extended was possible without a vibration problem.

  12. On return to Fort Rucker, the vibration problem was discussed with PAMI maintenance personnel. They advised that the retaining bands were made of 040 gauge steel whereas the blueprints call for 050 gauge steel. Also, seven rather than five tie-down cables per side should have been used on the tank. The reason for only five tie-down cables per side is that the tank was moved aft from its original position so it would not extend past the isolated floor. When this was done, only five cables per side would fit and, because of the mission requirement, there was not sufficient time to make and install the remaining cables.

  13. It is PAMI’s belief that lack of sufficient tie-downs allowed the tank to vibrate. The vibration in conjunction with the smaller gauge steel caused the retaining band to crack.

  14. Capt Bud Hill

    5 Oct 2013

    The photo shows where we landed near Wink Texas. Capt Les Rowbottam is on the left in Canadian flight suit, Lt Herb Degner, US Army Transportation Corps is on right. (Photo from Capt Bud Hill).

    Helicopter tug cargo hook.

    Tug's cracked aft pylon.

    Helicopter target airborne with 2000' cable.

    Helicopter target at lift-off.

    Tow cable on target helicopter.

    Tug touchdown.

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