HEP High Explosive Plastic, muzzle velocity 2,450 fps.
In this night-fire picture, the flat trajectory of APDS is very clear.
HEP-T at 2,000 Meters looks very different.
Now we reached the end of Table VIII Tank Gunnery 1976. The last engagement was a house—an
8-by-8-foot panel between 1,500 and 2,000 meters from the firing position. The ammunition is HEP-T—High Explosive
Plastic-Tracer, the slowest round that tanks fire. The actual rounds we fired is not the service
ammo pictured above but the powder-blue inert rounds.
This final engagement was truly different from the preceding
three main gun rounds because it was the longest shot with the slowest
round. When we fired APDS “SABOT” rounds
at the moving tank target at 1,000 meters distance, the round is traveling just
over a mile per second leaving the gun muzzle.
Even allowing for wind resistance, the time to a target roughly 3,300
feet away is less than a second. The
trajectory is essentially flat. For a
tank-sized target, it is point and shoot.
When we fired HEAT at 1,500-meter target, the
muzzle-to-target time was more than a second and I could see a ballistic arc,
but with a 3,850-foot-per-second speed out of the gun tube, the trajectory was
still close to flat.
For the final engagement my gunner was firing at a panel
nearly seven thousand feet away. The
HEP-T round has a muzzle velocity of 2,450 feet per second. So the time to target is nearly 3 seconds
(2.7 seconds with wind resistance). When
you fire SABOT at 1,000 meters, it is difficult to see the tracer at all. Firing HEP-T at this distance, the tracer
goes up, up, up in a straight line then drops rapidly at the end of its
parabolic trajectory.
As anyone knows who has watched a 70-yard touchdown pass,
the ball appears to go up for 60 yards then drop rapidly in the final ten
yards, right into the receiver’s hands.
Actually, the peak of the arc, whether pigskin or HEP-T round is half of
the travel time form the gun muzzle to impact.
So for this final engagement, every skill of tank gunnery
was important. When I issued the fire
command, the driver had to stop on what he saw as the most solid, level ground
possible. Any tilt of the tank would
send the round off target to the left or right.
For every engagement we had just fifteen seconds from the
moment we identify the target until the first round goes down range. No problem with a flat shot at 1,000
meters.
On the other engagements, I did not have to be perfect with
the range finder. On this target, I had
to have the range right or we would not hit.
While Merc, my gunner, refined his aim, I made sure I had the best
possible range, that my head was straight on the head rest and the sight
picture was as good as I could get.
With every other shot, Merc had a round down range
fast. With this one he made sure his
sight picture was as perfect before squeezing his electric trigger.
Then he said, “On the Way!”
I watched the round go down range for what seemed like
minutes. The red tracer went up in a
straight line then seemed to drop almost straight down toward the target.
Before the round hit the target, the loader yelled, “Up!”
then clambered up through the hatch. He
wanted to see the round hit.
Merc had the best view in the gunner’s seat with the sight
on the target.
“Hit!” I yelled on the intercom. “Damn,” Merc said looking through the
sight.
What I saw through the binoculars and Merc saw through the
primary sight was a dust cloud rising around the target, but the most important
part of what we saw was that we could see the panel for just a moment after we
saw the cloud. That meant the round
strike was behind the panel. Of course,
that could mean we missed by firing over the target, but we were pretty sure
the dust pattern said Hit!
I yelled, “Fire!”
Merc refined his sight picture then announced “On the Way!”
It looked like another hit.
I said, “Driver Move Out.” We rolled off the range.
As soon as the grader left the tank at the ammo point, we
started yelling and clapping and congratulating each other. We unloaded brass and rolled to the rally
point.
After night gunnery, which I really don’t remember well, we
scored “Distinguished.”
We hit every target during daylight gunnery and range
control confirmed we put a hole in the panel on the last engagement.
Before gunnery that year, I read the entire Dash 10
manual. I know the TM Number as well as
I know my Social Security Number.
9-2350-215-10.
I am in Army Aviation now and have had some great flights on
Blackhawk, Chinook and Lakota helicopters.
But I am not part of the crew.
For the years I was in tanks, I was crew. It really was the best job I ever had.
