Our rocket system is very simple. There are two seven-shot pods, one on each side. It must have been originally designed to fire one type of rocket, a 10-pound high explosive warhead (HE). With the advent of a variety of warheads and fusing, it had outgrown its control box. Our system control box has four positions, OFF, SINGLE, SALVO, and RESET. The control box has no ability to select individual pods, or even which pod.
OFF means that power is secured to the rocket system. We pulled the electrical power circuit breakers to be sure because it was such a Rube Goldberg afterthought lash-up that we didn't trust it.
SALVO automatically fires all 14 rockets, a pair at a time (one from each pod), in a continuous ripple fire of about 5 seconds. We'd never have a target to justify this option, but it was comforting as a jettison method since the pods were not electrically jettisonable.
SINGLE fires one tube per pod, sending a pair of rockets together, or sending a single rocket, depending on the setting of the intervalometer.
The intervalometer allows for some limited rocket selection. When the rocket firing button is pressed, electrical firing current is routed to an intervalometer on each rocket pod. While the rocket pod has seven tubes, the intervalometer has 14 positions, with positions 1 through 7 routing the electricity to a rocket tube, and positions 8 through 14 routing the electrical firing current to dummy positions (ground). In SINGLE, after the firing signal has been sent through both intervalometers, each intervalometer advances to the next position in order starting from where it was initially set. The intervalometer advances from 1 through 14 and then rolls over from 14 to 1, and through the numbers in order again.
To conserve rockets, we did not usually want to fire more than one rocket at a time. We can do this by manually setting one pod to position 1, and the other pod to position 8. As one tube is working its way from position 1 to 7 in order, firing rockets, the other tube is advancing from dummy position 8 to dummy position 14. After position 7 fires and advances to dummy position 8 on its side, the other pod is rolling over from dummy position 14 to position 1 (rocket tube 1), ready to fire a real rocket with the next press of the firing button (assuming tube one is loaded (we didn't always carry a full load of rockets because of our gross weight limits).
The intervalometers can only be set on deck, being located on the back of the rocket pods. In flight, all we can do is reset both intervalometers to the number 1 position from wherever they are by selecting the RESET position. Then the same tube is fired on both pods when SINGLE is selected and two rockets will be fired if the tube of one pod has not already been fired. That is the extent of our control.
The electrical firing current explodes a primer charge in a cap at the tail of the rocket, which ignites the solid fuel rocket motor and launches the rocket. As the rocket leaves the tube, the disintegrating rocket cap flies apart and frequently frags the crewman who is seated just in front of the muzzle of the rocket pod. It is common for gunners to come back from a hot fight bleeding from numerous stinging cuts on the legs, arms, and in the part of the face not covered by their helmet visor. This "fragging" could be avoided if the gunners moved back into the cabin when the rockets were being fired. Unfortunately, they can't shoot from in there, and they need to be shooting. They really need to be shooting. They WANT to be shooting. So they eat rocket caps; all in a night's work. Occasionally, the lower legs of the pilot are also peppered. The armor plate protects most of the body, but not the legs. This minor irritation to the pilots could be avoided if we closed the pilot's doors, if we had pilot doors. We usually didn't even have them installed; useless weight.
We had two types of fuses for our rockets, proximity (prox), and contact, often called point-detonating (point-det). It is not always desirable to shoot point detonating fuses. Sometimes you want to use proximity fuses. Usually our targets are in the trees and bush. In that case, we want point det, which will penetrate farther into the stuff before going off. It also makes shrapnel of the wood it hits, improving the chance of hitting an enemy soldier with something which could hurt him. If the enemy is caught in the open, he is in mud, or in water, a point det will be smothered with the mud or water absorbing much of the explosive effect and venting most of the rest straight up, relatively harmlessly. In that situation, a proximity fuse is best. It goes off before hitting the ground in an air burst, maximizing the frag in the air. Because of the nature of the "ground," a mix of solid, tree-covered mud, and liquid, open paddy-swamp canals and creeks, we usually alternated each position in each pod; prox, point-det, prox, etc.
We have four types of warheads to choose from; HE (high explosive-frag), WP (white phosphorous), smoke marker (no kill explosives), and fleshettes (2400 little steel darts). The fleshettes are shotgun-like warheads for use against large concentrations of troops. White Phosphorous or "Willy Pete" is an incendiary warhead which can start a fire which water can't douse. It makes a large white smoke cloud, like a smoke marker rocket warhead, except WP will also do some hurt if any flakes get on you, or your flammable structure.
Since we are unable to select a specific individual rocket tube, other than using the RESET function, planning the optimum rocket load for a "routine" patrol or for a scramble is tough. Up on the Cambodian border, in an open country interspersed with clusters of undergrowth and groves of trees, and where every canal or creek is lined with tree-bush growth, and where concentrations of troops have sometimes been encountered, we might put a fleshette in the last tube of each pod. That way, should we luck out and find a worthwhile troop concentration; hitting reset would allow a large volume of rapid fire ending with two fleshettes. We sometimes put a prox willy pete in the first tube of each pod. It was excellent to mark the target initially. We never bothered with smokes. Who needs harmless pretty colors?
Down on the coast of the South Chine Sea in the dense mangroves, we skipped both willy pete and fleshettes because of the high density of the growth. Anything needing marking could be done with hand dropped smoke grenades, or an M-79 smoke round, launched at low level, and the chance of finding any number of troops in the open was nil.
Of course a specified mission with good intell might allow us to plan to use a lot of willy pete or a bunch of fleshettes, all prox or all point det. And once we were in a fight, we would know the terrain and be able to "optimize" our rocket load when we rearmed after the initial strike. It wasn't very often, however, that we would get into the kind of standup fight where the VC would wait while we rearmed and came back into the fight.
Because we don't usually have a massive or large target, and to be as accurate as the rocket system will allow, we normally fire one rocket at a time. The rockets weathervane horribly because of the seesaw yaw characteristics of the Huey (it had no autostab system) and because of the rotor downwash which aggravated the power setting when firing. To shoot accurately, you tried to roll in at a shallow dive angle from the same altitude and distance every time, with the same power setting. In theory (we were taught in Army airborne gunnery training back at Fort Rucker, Alabama), that set up the same conditions for each shot. At Rucker, on the rocket range, in a light helicopter, with the same winds for each run down range, it might be true, but in the world, the tactical situation often precluded such attempts at precision or consistency. Firstly, you didn't often want to fly the same route in run after run, unless it was adjacent to friendlies; you were just asking to get ambushed from the ground. As you rolled in from differing directions, the winds changed relative to the aircraft, and the weight of the aircraft changed as the fuel and ordnance was consumed (faster than a light training helo at Rucker). This was a relatively big difference in such a low gross weight aircraft.
You arrive at the push point on speed and with the desired power set and push over. You then try to get the pipper on target as fast a possible before the accelerating helo throws off the sight picture too much. Then you move cyclic, left-right, up-down, and "cheat" with the collective a little to compensate for the cross-wind (its ALWAYS a cross wind, even on a still day, when you try to shoot rockets). Now the pipper is not on target any longer, but is off by your allowance for windage. Cross check the ball; it MUST be centered. If it's out a little you must move the nose and squeeze the collective as you feed rudder to get the pipper back to the desired position after adjusting for the rudder movement. When first learning to shoot rockets, you might find yourself at break off altitude without ever getting the right combination of ball, collective, sight picture, and sink rate to squeeze off a rocket.
When you get it right, or close enough, you press the firing button without "flinching" the cyclic (just like firing a rifle, you can throw off the shot by jerking the trigger). It helps to be a down home country boy raised with a rifle in his hand; the principles are the same as far as windage, but it's different to be the moving "pheasant" shooting at the stationary "hunter."
At first you are amazed to see your rocket going off in an entirely different direction from the aim point, usually high or low, but frequently left or right, or the ever popular combination; anywhere except at the aim point. It seems, for the longest time in the education of a rocket marksman, that the safest place on earth is right on the aim point. You begin to wonder why they didn't make the warhead bigger to compensate for these impossible weapons (some days a nuke wouldn't be enough it seems). And just when it seems that the rocket is making a bee-line for the aim point, the rocket motor burns out and the ballistic weapon curves gracefully down to explode short of the aimpoint. Oops, forgot about that part. This is a little easier in fixed wing, with a more stable aircraft, fewer controls to adjust, higher speed, and steeper dive angles. The fixed wingers also fire all their rockets on a single run and let the sheer numbers compensate for the inaccurate individual rocket; they don't do CLOSE air support like us. It's a LOT easier with the longer-burning motor, larger warhead, and supersonic velocity of the 5-inch Zuni rocket, which burns all the way to the target. The accuracy and punch of the Zuni make the Black Ponies of VA(L)-4, a highly desirable partner in our little combat family in the Delta.
You quickly learn to quickly manhandle the aircraft into approximate alignment and shoot quickly and be objective about the first rocket (it is always something of a guess), and you concentrate even more effort to adjust the next rocket toward the target based on where the first one hits. In this manner we walk the fire to the target in a technique called "burst on target." You kept the reticle on the target until the rocket exploded, noting the explosion location on the sight relative to the reticle (and the target), say low and to the left of the target, then you "fly" the burst spot on the sight reticle up to the target, in this case, up and right. Now adjusting for the increased speed in the accelerating dive, and shorter ballistic fall after motor burnout because of closure on the target area, both of which will throw off the next shot, if not accounted for, you make sure the ball is still in the center, and squeeze off the second rocket. Repeat as time permits or as weapon effect requires (sometimes you actually hit the target and another rocket is not required). With practice, we'll normally get off two or three aimed rockets per rocket run. That is the way to be most accurate with a less than precision weapon.
Add to these firing limitations, the joker in the deck. The solid fuel may have been altered by sweating in the sun, or the fuel mass may have been dried and cracked by the sun, causing an uneven motor burn and asymmetrical thrust, so that the rocket would not fly true even if aimed and fired with great care.
There is one more variation to the simple calculus of 2.75" rocketry from a UH-1 helicopter. In addition to the types of warhead, the HE warhead came in two sizes, 10-pound, and 17-pound (10-#, 17-#). Nothing else changed on the rocket, just the weight of the warhead affixed to the front of the same rocket motor. Result? After rocket motor burnout, the ballistic travel of the two types is different. Fired on the same initial trajectory, the heavier-nosed 17-# warhead would not fly as far. It curved down more and sooner, of course, making it even less "accurate" or perhaps "predictable" than it's little brother, especially if mixed with the 10-# warheads. To be safe, and consistent, we learned to avoid mixing them. Since there were not a whole lot of them around, we usually didn't use the 17's. A hit with a 10-# warhead was preferable to a miss with a 17-# warhead; the bigger bang did not make up for the reduced accuracy. We never fired enough to "learn" where they would go after burnout like we did with the 10-# warheads.
As well as learning not to mix the two different warhead weights, we learned not to shoot a prox fuse rocket immediately after any other rocket. If you were a good rocket shooter, your second rocket would follow closely behind the first as you learned to gauge where the first was going even before it hit. This caused potential trouble if the prox fuse "saw" the wake of its predecessor. That disturbed air was "hard" enough to cause the fuse to detect proximity and dutifully detonate. . . right in front of the helicopter. Now life is dangerous enough without flying through your own shrapnel from a frag warhead going off right in front of you - FLAK!
Tactics using rockets were driven by these firing accuracy considerations. Unless absolutely unavoidable, we never planned our runs to go over friendly positions. Once you were a competent rocket marksman, if you were going to be off, you tended to be low or high in line with your pass, and not as much off left or right (disregarding bad motors). Break off the run and turn over the friendlies. Then if the VC fired at you they were targets for the friendlies. Of course, our gunners were also firing when we broke off the rocket run, and the brass rained down on the ground troops. Funny, we never heard a complaint about that brass. Probably because they knew that every round bouncing off their backs and helmets meant a full metal jacket heading for the VC. The VC often tended to try to get close to the friendly ground troops for protection from air strikes and artillery, in a tactics now known as "grabbing the American's belt." This seemed to work for other aircraft, who would refrain from working their ordnance in close. We, on the other hand, would switch to our gunners and work their fire right up to the friendlies, using concentrated aimed fire, not sprayed fire. We never ever heard of any friendly casualties from our fire, and had many cases of ground troops asking us to put it closer. They trusted our guns, and we worked to keep that trust.
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Copyright © 2002 Tom Phillips