CISS Tow Rope Guidelines - Central Indiana Soaring Society

CISS Tow Rope Guidelines
Tow ropes are a critical component of CISS operations with important safety and regulatory requirements.
The situation is complicated with the variety of materials available, various assembly techniques and specific
requirements by individual glider Flight Manuals or Type Certificate Data Sheet specifications which override
the FAR’s. The final decision to use or reject a rope is the responsibility of the pilot in command; but, the club
can simplify this decision by having a standard and consistent procedure for tow rope materials and
assembly techniques along with several members trained to assemble and maintain the tow ropes.
Assemblies
Three Tow Rope assemblies are required for normal CISS operations. These assemblies and the materials
required are:
1. Tow Rope – For normal use at Alexandria with Tost Hook equipped sailplanes
Materials:
1 --- 200 ft 3/8” hollow braid PolyPro for main rope
2 --- 8 ft 5/16” hollow braid PolyPro for weak links
2 --- 4” 5/8 clear Vinyl Tubing
1 --- Schweizer Ring
1 --- TOST Ring
1 --- Plastic Ring Protector
.032” Safety Wire
Gorilla Tape
Assembly:
o 5/16” Weak Link with Schweizer Ring and Vinyl Tubing on one end.
o 5/16” Weak Link with Tost Ring and Vinyl Tubing and Plastic Ring Protector on other
end.
o Tape joints to protect from abrasion
2. Short Tow Rope – For aero retrieves from short fields.
Same as Tow Rope except use 150 ft 3/8” hollow braid PolyPro for main rope in place of 200 ft
rope.
3. Schweizer Adaptor - A short link to attach to the Tost Hook for towing Schweizer Hook Sailplanes such
as the CISS Schweizer 1-34.
Materials:
1 --- 11 ft 5/16’ hollow braid PolyPro
1 --- Schweizer Ring
1 --- 4” 5/8 clear Vinyl Tubing
.032” Safety Wire
Gorilla Tape
Assembly:
o Schweizer Ring and Vinyl Tubing on one end.
o 4” rope loop on other end without Vinyl tubing.
o Tape joints to protect from abrasion
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Weak Links
The Weak Link is assembled using a 8 ft length of 5/16 PolyPro rope. A 4” length of 5/16” Vinyl tubing and
a tow ring (Schweizer or TOST as appropriate) are placed over one end of the rope. At a point 28” from the
end of the rope, the end is inserted into the center of the rope. It is threaded through the rope for 8” and
then brought out the side. It is then passed over two strands, which form an “X” and then goes back through
the rope, over two strands and back into the center of the rope. The Locking Loop should then be pulled
tight so it almost disappears. At an additional 8” this process is repeated. When the end is completely
inserted into the center, the outside rope should be worked up toward the ring and the end of the rope
should be brought out the side. The rope is cut at an angle to reduce the abrupt change in cross section and
then worked back into the center of the rope. Details for this procedure are shown below. The joints
identified with vertical lines in the diagram below should be wrapped with Gorilla Tape to protect the joint
from abrasion.
In Line Splice
This procedure is used for attaching weak links to main tow rope and for splicing main tow rope if it is
necessary to splice it after a short damaged section has been removed.
When splicing weak links place a Plastic Ring Protector on the weak link with the TOST Ring. The weak link
with the Schweizer Ring on the other end does not use a protector. Insert smaller rope through side of
larger rope 8” from the end and thread it down the center for 8”. Bring smaller rope out the side, it is then
passed over two strands, which form an “X” and then goes back through the rope, over two strands and
back into the center of the rope The Locking Loop should then be pulled tight so it almost disappears.
Repeat twice more. When the end is completely inserted into the center, the outside rope should be worked
up toward the ring and the end or the rope should be brought out the side. The rope is cut at an angle to
reduce the abrupt change in cross section and then worked back into the center of the rope. Details of this
procedure are shown below. The Joints identified by the vertical lines below should be wrapped with
Gorilla Tape to protect them from abrasion.
When making a splice in the long rope after removing a damaged section or to repair a cut, the above
procedure is used, however both ends will be the same diameter and it makes no difference which direction
the splice is oriented.
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Examples
TOST Ring – Tubing – Safety Wire Tie
TOST Adaptor – Same as Schweizer except for Ring
Rope coming out at 8” for Locking Loop
Rope being reinserted past “X” for Locking Loop
Locking Loop after being pulled tight
Angle cut on end before being pulled back into rope
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Vendors and Materials
Source
Wings and Wheels Soaring Supplies
2049 Shadyside Road
Lakewood, NY 14750
716-763-3213
[email protected]
o
o
o
o
5/16 CSR (David Bradley) Hollow Braid PolyPro
3/8” CSR (David Bradley) Hollow Braid PolyPro
Schweizer Rings
TOST Rings
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Vendors and Materials
Source
Aircraft Spruce East
452 Dividend Drive
Peachtree City, GA 30269
800-861-3192
o .032 Safety Wire
Source
Local Hardware Stores
o 1/2” OD x 3/8” ID Vinyl clear tubing
o 5/8” OD x 1/2”ID Vinyl clear tubing
o Gorilla Tape
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CISS Fleet and Member Private Sailplane Tow Rope Requirements
Gross
Owner
N#
Make Model
FAR
Weight
80%
200%
Max
Flight
Manul
1662
1460
1460
CISS
CISS
CISS
CISS
7676
45748
809S
303BA
SGS 1-34
Grob 103
Blanik L-23
Blanik L-23
840
1279
1124
1168
672
1023
899
934
1680
2558
2248
2336
Ron Clarke
Dan DeWitt
Josh Daisey
Terry Dickey
John Earlywine
Brad Hays
Mike Nichols
Scott Ortman
Nyal Williams
Tom Ruble
George Sanders
Jerry Simpson
Dave Stanley
60ZA
41XX
42RD
727AM
1RN
14SZ
676
888TK
888TK
7FR
7FR
30DX
787AM
Ventus 2C
LS-4
RS-15
ASW-20
DG-1000
Discus B
Std Libelle 201B
Discus B
Discus B
SZD-55-1
SZD-55-1
Discus B
ASW-20B
1157
1040
926
832
2314
2080
1157
1650
1160
770
1160
1160
1100
1100
1160
1000
926
1320
928
616
928
928
880
880
928
800
2314
3300
2320
1540
2320
2320
2200
2200
2320
2000
Length
min 130 ft
min 50 ft
min 50 ft
Recommended 100-130 ft
Recommended 100-130 ft
1499
2200
1499
Recommended 100-230 ft
1499
1499
1499
o The CISS Chief Flight Instructor has responsibility to update CISS fleet data as appropriate
o Individual Owners are requested to review and request updates to their individual data to assist CISS in planning for
and providing tow ropes which meet their individual requirements
o This data is for planning purposes and individual owners are solely responsible for determination of the suitability of
tow ropes for use with their sailplanes
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