II. AERIAL DELIVERY
Aerial delivery, although it may
not be totally correct, is the total process of the
delivery of cargo (or supplies) and heavy equipment. Cargo
(not sure this was the official name) parachutes were
similar to that used by personnel, except the material and
construction were heavier. The packing process of the cargo
parachutes was similar to the that of personnel
chutes.
When loaded on a C-119 some
cargo chutes were hung from an electrically-operated
monorail for rapid movement to the rear and ejection from
the aircraft, as shown in the photograph to the
right.
I don’t remember the
weight limit for a cargo supply parachute, but it was
probably on the order of the weight of a man. I don’t
remember them being as large as a T-10, but larger than the
T-7A reserve chute. Most of the supplies were dropped with
cargo chute. They were easier to pack, handle, load, and
could automatically or manually dropped out of the
aircraft. I think the aircraft rear shells were usually off
for a cargo drop and the supplies were dropped out the rear
of the aircraft. However, they could be pushed out the side
door – like us.
I usually think of
“Aerial Delivery”, as the dropping of
equipment or Heady Drop. PS&M Co had a Heavy Drop
Section that specialized in heavy drop. Looking back on the
concept of Heavy Drop, as an engineer, it was a much more
complex process than I had thought at that time. For Heavy
Drop the parachute material was heavier. The webbing,
tie-downs, harnesses and everything else are stronger and
heavier. To put a Heavy Drop parachute in
prospective:
The parachute used to drop heavy
equipment was the L G11. It had a diameter of 100 feet and
when packed weighed 250 pounds. These parachutes could be
used as a single or in groups of up to four, depending on
the total weight of the load.
The L G11, is shown at the left.
Note its size relative to a man and a Semi-Truck.
This photo was taken in
Gablingen, Germany. Shown in the rear is the PS&M
Company’s “Pack Shed”
The Aerial Delivery Phase of
Rigger School was interesting and a lot of hard work. We
actually learned to pack the aerial delivery parachutes
during the Parachute Packing Phase although I did not
discuss it in that phase.
As shown above the Heavy Drop
parachute was very large and heavy. It took a team of four
Riggers with at least two others helping who were not
required to sign the parachute log book. Large fans (one is
shown behind the Semi in the photo above) were used to help
partially inflate panels so they could be folded much like
the personnel parachute. (If a Rigger reads this that is
familiar with the packing of these parachutes I could use
some help – 50 years is a long time to rely on just
memory.) Two explosive charges were installed during the
packing process. They will be discussed in the description
of how the chute works a little later.
RIGGED HEAVY EQUIPMENT
Some of the equipment we rigged
and dropped during Rigger school are shown in the following
photos.
Large amounts of supplies could
also be dropped on a platform as shown on the right.
At left is a 105 Howitzer rigged
for heavy drop. It was dropped with one parachute.
M38 ¼ Ton Truck –
“Jeep”
Component
Weight Pounds
Vehicle
2,625
Platform
450
Accessories
330
Parachutes
250
Total Weight 7,687
Number Dropped from C-119 = 3
Type of Chute = (1) L G11 (100 ft-diameter)
Rigging Time = 20 Minutes
Ejection Time = 3 Seconds
Preparation for ground use = 4 Minutes
Cost of Kit = $ 803.85 (1955)
(Information from back of photo.)
Things did not always go
according to plans.
Note the “canyon” on
the DZ we used during Rigger School. A vehicle went into
one and it was very difficult to get out.
¾ Ton Truck
Component
Weight Pounds
Vehicle
5,917
Platform
740
Accessories
330
Parachutes
500
Total Weight 7,687
Number Dropped from C-119 = 3
Type of Chute = (2) L G11 (100 ft-dia)
Rigging Time = 40 Minutes
Ejection Time = 3 Seconds
Preparation for ground use = 5 Min.
Cost of Kit = $1,081.90 (1955 $)
M34 2½ Ton Truck
“Duce & Half”
Component
Weight Pounds
Vehicle
11,775
Platform
1,760
Accessories
1,087
Parachutes
1,000
Total Weight
15,622
Number Dropped from C-119 = 1
Type of Chute = (4) L G11 (100 ft-dia.)
Rigging Time = 60 Minutes
Ejection Time = 3 Seconds
Preparation for ground use = 4 Minutes
Cost of Kit = $ 2,363.15
As can be seen in the photograph
the load sits on a lot of “shock” pads. They
are pillow-like of about a foot square and 2 –
3 inches thick each. When the platform hits the ground the
pads absorb a lot of the shock. The frame structure under
the bumpers are made of wood. There are several horizontal
pieces of 2 x 4 wood beams that are part of the structure.
Their purpose is upon landing, as the pads compact the
bumpers will shatter the wood structure and absorb more of
the impact.
Another picture of a 2 ½
Ton Truck being loaded for transportation to the
aircraft.
It was an interesting sight to
see a C-119 trying to get off the ground with this load
inside it. They would actually use the entire runway. It
appeared as if the pilot raised the wheels to become
airborne!
It worked!
At right is a shot of a heavy
drop. The three chute load in the center is the 2½ -
Ton Truck and the two chutes are ¾ ‑Ton
Trucks.
HEAVY EQUIPMENT DROP
SEQUENCE
A view, at the left, of a C-119
with its rear shells removed. It is being loaded with a
piece of equipment, probably a 105 Howitzer or a
jeep.
On the floor at the rear of the
aircraft is a release mechanism that can be controlled by
the pilot. Attached to it is a weight which is also
attached to a “Pilot Chute”. This parachute
resembles the ones we made with a handkerchief when we were
kids, but a little larger - about the size of a bandana.
During flight when the weight was released it pulled the
Pilot Chute out. The Pilot Chute was also attached to the
heavy drop load via the Ribbon Chute.
The function of the Pilot Chute
is to pull out and help inflate a Ribbon Chute which is
attached main parachute bag(s). The Ribbon Chute is very
similar to that used on fighter planes to help slow them on
short runways. The space between the ribbons, which are
circular flat strips, provides a path for the air to escape
so that the chute. It has enough are to provide an anchor
force, will not be ripped apart.
The load is tied-down to the
aircraft floor by several pieces of webbing that takes
about 4,000 pounds each to break. However, nylon does not
take shock loads very well and that is what the Ribbon
Chute exerts. The nylon straps(tie downs) are easily
snapped and the Ribbon chute extracts the load. The Ribbon
Chute can be seen at the far left of this picture.
Continuing the extraction
sequence, the load comes out the rear of the aircraft very
fast. (You do not want to be between the rear of the
aircraft and the load when the pilot pulls the release to
drop the weight.) The force exerted by Ribbon Chute on one
end and the weight of the load on the other pulls out the
suspension lines and the canopy from the deployment bag. As
the suspension lines are deployed one suspension line arms
two explosive charges. Each is a rectangular metal
container (about 4 - 6 inches long and about 1 inch square)
containing a timer and an explosive charge, about like that
used in a bullet. The two containers are identical except
one has a “3” stamped on it and the other a
“10” indicating the time delay in seconds.
These charges can not be seen after the parachute is
packed. It is very important that each is installed in its
proper place.
The explosive charge with the 3
second delay has the Riffing Line, which goes around the
base of the canopy, passing through a hole at one end. The
purpose of the Reefing Line is to restrict the inflating
canopy to only 15 feet of its 100 foot diameter. This is
shown is the photograph to the right.
Restricting the diameter to only
15 feet reduces the shock of the load on the canopy. When
more than one parachute is required the Reefing Line
insures that each canopy is partially inflated before
allowing them to fully
inflate at the same time.
The reason this is important is
that if one canopy should inflate before the others the
load could rip it apart and then when the next canopy
opened it would also be overloaded and would also be
ripped. Three seconds after deployment of the suspension
lines the explosive charge goes off . It drives a knife
blade towards the hole in the container that the Reefing
Line passes through cutting it into. This allows the
canopies to inflate to their full 100 foot diameter and
slow the falling load.
The harness, attached to the
load, is held to the suspension lines by a clamp mechanism
that resembles your hands when you curl your fingers around
each other. Similar to the hole created along the width of
your palms and between your fingers is a space between the
two halves of the clamp mechanism. A steel pin, about 3 - 4
inches long and 1 inch in diameter, is inserted in this
space. The pin will hold the clamp together and thus the
load to the parachutes. After 10 seconds of the deployment
of the suspension lines the second explosive charge goes
off and drives the steel pin out. Now the two haves
of the clamp mechanism are held together only by the weight
of the load. Shown to the left is a Heavy Drop of equipment
using two parachutes.
The purpose of removing the
steel pin before the load hits the ground is, that unlike
you, the load cannot get up and run around the canopy and
collapse it. With the steel pin out the clamps will rotate
and come apart when the weight of the load is removed. The
canopy(s) can then float free of the load. Without the
weight of the load to help keep the canopy inflated it will
begin to collapse as shown on the right.
Without this sequence occurring
the parachutes can easily drag the load across the DZ. The
results is what occurred to the jeep shown in a previous
picture.
[HOME]
[TOP]
[CONTENTS]
[PARACHUTE MAINTENANCE]
Visits This Site
FastCounter by bCentral
