Chevron cutting is shown to occur in different forms depending on the type of tire  and the rubber on the running surface. Hardest wear is shown by the main tires of the B-747. Four defects occurred, in the form of two rip separation and two breakouts of the running surface. Tires capped by Thompson are more affected than any of the other rubber-capping fabrics. For Thompson tires, Chevron Cutting is greatly reduced with a fiberglass-rubber mixture. For Goodyear tires, it is eliminated with spiral wrap rubbercapping; resistance to damages through cuts seems to be more positive for Goodyear tires. For Mader tires, the extent of Chevron Cutting is generally smaller than for Thompson cappings

Tyran, K.

English

NASA Technical Reports Server

NASA TECHNICAL MBMORANDUM NASA 4-75448 
CHEVRON CUTTING--EXPERIMENT WITH NEW
 
RUNWAY MIXTURES
 
K. Tyran
 
(NASA-T-75448) CREVRON CUTTINS: 
 N78-32427
EXPxRMIENT WITH Nizw RUNWYM IXTUl2S3 
fNatialnal Aeronautics and Space

Adxdnistration) 31 p HC AO3/MF Aol CSCL llJ nclas
 
G3/37 31610
 
Translation of "CHEVRON CUTTING--Versuch Tait
 
neuen Laufflachenmaschungen," , 
.Tec!bizVersuchsberzcht, ab1.No. 7 2 1753 
Dec. 22, 1-977, 20 pages._
 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
 
WASHINGTON, D C. 20546 SBPTENBBR 1978
 
https://ntrs.nasa.gov/search.jsp?R=19780024484 2020-03-22T01:56:27+00:00Z
STANDARD TITLE PAGE 
I Report No 	 2 Government Accession No 3 Recipient's Catalog NoNASA Tm-75448 
4 	 Title and Subttle 5 Report Date 
CHEVRON CUTTING--EXPERIMENT WITH NEW' September 1978
 
RUNWAY MIXTURES 	 6 Performing Organ.otion Code 
7 	 Author(s) 8 Performing Organization Report No 
K. Tyran, Swissair-Technical
 
Department 10 Work Unit No
 
S11 	Contract or Grant No 
9 	 Performing Organization Name and Address ,fASW-3199 
Leo Kanner Associates 13 Type of Report and Period Covered 
Redwood City, California 94063 
Translation 
12 Sponsoring Agency Name and 
Address 
National Aeronautics and Space Admin- 14 SponsoringAgencyCodo 
istration, Washington, D.C. 20546 
15 	 Supplementary Notes 
Translation of "CHEVRON CUTTING--Versuch mit neuen
 
Laufflichenm schungen," Swissair Dept Technik,
 
Veruchbercht Tbl. No. 72/W78, Dec. 22, 1977, 20 pages.
 
16 	 Abstract
 
Chevron cutting occurs in different forms depending on the type of tire
 
and the rubber on the running surface Hardest wear is shown by the
 
main tires of the B-747. Four defects have occurred, in the form of
 
two rip separations and two breakouts of the running surface.
 
Tireg capped by Thompson are more affected than any of the other rubber­
capping fabrics For Thompson tires, Chevron Cutting can be greatly
 
reduced with a fiberglass-rubber mixture For Goodyear tires, t
 
can be eliminated with spiral wrap rubbercapping; resistance to damages
 
through cuts seems to be more positive for Goodyear tires. For M Ider
 
tires, the extent of Chevron Cutting is generally smaller than for
 
Thompson cappings.
 
17 	 Key Words (Selected by Author(s)) 18 Dstriution Statement 
Unclass ifiedrUnlimited
 
19 	 Security Cossif (of this report) 20 Security Classif. (of thispage) 21 No ofPages 22 Price 
Unclassified Unclassified
 
NASA-HQ 
CHEVRON CUTTING--EXPERIMENT WITH NEW
 
RUNWAY MIXTURES
 
K. Tyran
 
Swissair-Technical Department
 
1. Explanation /_]
 
Since the introduction of the new runway construction
 
with crosswise running grooves damages to the running surfaces
 
occur in the form of V-shaped breaks which are designated as
 
"Chevron Cutting".
 
These damages occur upon landing when the stationary tire
 
touches the grooved runway and slides over the groove edges.
 
Chevron Cutting is influenced by tire pressure, touchdown
 
velocity and mass moment of inertia of the wheel (Figs. 1, 2,
 
3).
 
After the start of operation with grooved runways a reduc­
tionxinthe efficiency of tires used for landing was recorded.
 
Since Chevron Cutting also had negative effects on the possi-,
 
bility of keeping damages through cuts under control and
 
presumably offers less resistance to the penetration of foreign
 
bodies, an experiment (Publ. Nr. 72'539) was carried out with
 
new running surface constructions.
 
Numbers in the margin indicate pagination in the foreign text.
 
Compiled- Checked. Reviewed:
 
K. Tyran, TZMPP E. Rueger, TZMP E. Schientarelli
 
TZM
 
2. Running Surface Fabrics--Description
 
2.1 Thompson
 
A rubber mixture reinforced with fiberglass was developed
 
especially against Chevron Cutting by the firm of Thompson--

USA. The fiberglass fibers are 3 mm long and 0.03 mm dia. and
 
are mixed with the rubber of the running surface above the re­
inforcement layers only. In the bonding region between carcass
 
and rubber capping no change was made in the rubber mixture.
 
Tires of such construction were put into operation in the USA
 
several years ago. In addition to the rubber mixture rein­
forced with fiberglass, 2 tires with running surfaces made of
 
natural rubber were tested.
 
2.2 Goodyear
 
A so-called "spiral wrap" running surface construction
 
was developed by the Goodyear Company. This is a reinforce­
ment of the running surface through cord threads in the rubber
 
of the running surface. The threads are applied with the un­
vulcanized rubber strip, circumferential in spiral-form,
 
through a special rubbercapping process (Orbitread). Tires of
 
such construction have been made in the USA for the past S
 
years. Fig. 4 shows the distribution of the cord threads in
 
the running surface.
 
The running surfaces of the Goodyear Company consist of
 
natural rubber in contrast to the other products which contain
 
a certain amount of synthetic rubber.
 
2.3 Mader 

The Mader Company has developed a soft rubber mixture
 
which has not been tested so far
 
/2 
Physical data:
 
Normal
 
Characteristics tested Mixture
 
on Plates, Vulc. 4S'/ Soft AB 1910/5
 
140'C, VSM-3-Dumb- Mixture (newest
 
bells AB 5550/1 mixture)
 
Hardness Shore A 60 64
 
Tensile strength kg/cm2 256 240
 
Elongation % 570 490
 
Module 300% kg/cm2 100 126
 
Notch tensile strength kg/cm2 110 longitud. 110
 
(Delft) 140 across 138
 
Wear mm 3 45 43
 
% Stand. 38 37
 
3. Experiment
 
3.1 Description
 
The two B-747 aircraft were designated for the service
 
evaluation because the tires of this type of aircraft are
 
strongly affected by "Chevron Cutting" and because their fAvor­
able route structure permitted good monitoring.
 
The tires were mounted in pairs, i.e., one tire of the
 
presentzmaterial and one of the Chevron Cutting-resistant con­
struction was mounted on the same axle. This was an attempt
 
to arrive at equivalent evaluations.
 
The criteria for evaluation are*
 
--Susceptibility to "Chevron Cutting"
 
--Wear
 
--Sensitivity to cuts
 
3 
Wear was measured at 4 locations of the circumference and
 
an average value was formed.
 
Two values of wear were determined in each case since wear
 
is greater at wheel positions 7, 8, 11, and 12 than at the
 
other MLG wheel positions.
 
Remaining depth of grooves and the premature going out of
 
service,because of damage through cutswere not taken into con­
sideration for the average number of landings achieved with the
 
test tires.
 
Nine pairs of tires were sub3ected to the tests for each /3
 
rubbercapping material. Direct comparison between the three
 
fabrics tested, as regards wear and Chevron-Cutting suscepti­
bility, cannot be made since the tire fabrics were not subject
 
to the same loads, resp., the same weather conditions.
 
The tests were carried out during the following periods,
 
Thompson: November 1976-March 1977
 
Goodyear: February 1977-May 1977
 
Mbder- April 1977-June 1977
 
3.2 Thompson
 
3.2.1 "Chevron-Cutting"-susceptibility
 
The running surface mixture, which was reinforced
 
with fiberglass, showed remarkable improvement when compared
 
to the previous running surface mixture with regard to suscep­
tibility to "Chevron Cutting."
 
4
 
There were,no Chevron Cuts on two of the nine test
 
tires. They did appear on the remaining seven test tires but
 
to a much smaller extent than for the previous running surface
 
mixture. The breaks are up to 8 mm long and about 0.8 mm deep,
 
For the previous mixture breaks were as much as 40 mm long
 
and 3-4 mm deep (see Figs. 5, 6, 7 and 8). Two of the tires
 
capped with natural rubber showed better performance with re­
gard to Chevron Cutting than those with the previous running
 
surface mixture.
 
3.2.2 Wear
 
Wear at wheel positions 	 1-6, 9, 10 and 13­
16
 
Previous running surface 	 0.025 mm per landing
 
mixtuThe : 
Fiberglass teinforcement. 0.031 mm per landing
 
Natural rubber mixture 0.029 mm per landing
 
Wear at wheel positions. 7, 8, 11 and 12
 
Previous running surface
 
mixture: 0.037 mm per landing
 
Fiberglass reinforcement 0.059 mm per landing
 
Average wear is about 20% greater all over for the
 
fiberglass-rubber mixture.
 
Average number of landings achieved.
 
Previous running surface mixture. 153 landings
 
Fiberglass reinforcement mixture: 129 landings
 
3.2.3 Sensitivity to Cuts 

Based on visual checks of the test tires sensitivity
 
to cuts seems to be rather higher for the fiberglass-compound
 
S
 
/4 
tires. But reliable answers about the sensitivity to cuts can
 
only be supplied after more extensive experiments.
 
3.3 Goodyear
 
3.3.1 "Chevron Cutting"-susceptmbility
 
The "spiral wrap" construction of the running surface
 
has shown the best performance of all tested fabrics with regard
 
to Chevron Cutting. No Chevron Cuts appeared on the tires
 
tested.
 
Fig. 9 shows Chevron Cutting on a normal running
 
surface construction. Fig. 10 shows a worn-out "spiral wrap"­
tire.
 
3.3.2 Wear
 
Wear at wheel positions 1-6, 9, 10 and 13-16
 
Previous running surface
 
construction 0.070 mm per landing
 
SPIRAL WRAP: 0.071 mm per landing
 
Wear at wheel positions 7, 8, 11 and 12
 
Previous running surface
 
construction: 0.090 mm per landing
 
SPIRAL WRAP: 0.096 mm per landing
 
There is no difference in wear, resp. landing effi­
ciency, between the normal running surface construction and the
 
spiral wrap running surface.
 
6 
Average number of landings achieved:
 
Previous running surface
 
construction (new tires) 101.4 landings
 
SPIRAL WRAP (recapped
 
tires): 120.3 landings
 
Note Since the Goodyear Company has so far not
 
carried out any cappings for the B-747 comparative
 
experiments had to be carried out between new tires
 
and recapped spiral wrap tires. New tires have a
 
groove depth of 8.9 mm and cappings of 11 mm. This
 
is the reason for the number of landings being
 
smaller for new tires.
 
3.3.3 Sensitivity to Cuts 

Based on visual checks the spiral wrap tires seem to
 
show better performance with regard to damage from cuts. Reli­
able statements can only be made about F.O.D. performance after
 
more extensive experiments.
 
3.4 Mader
 
3.4.1 "Chevron CuttingU-susceptibility
 
The softer rubber mixture showed no difference from
 
the previous normal running surface mixture with regard to
 
susceptibility to Chevron Cutting. Length and depth of the
 
breaks is also about the same for both mixtures. Figs. 11 and
 
12 show the extent and Figs. 13 and 14 the characteristic of
 
Chevron Cuts on Mader rubber cappings.
 
7
 
/5 
3.4.2 Wear
 
Wear at wheel positions 1-6, 9, 10, and 13-16
 
Previous running surface
 
mixture. 0.051 mm per landing
 
Soft rubber mixture- 0.053 mm per landing
 
Wear at wheel positions 7, 8, 11 and 12
 
Previous running surface
 
mixture 0.061 mm per landing
 
Soft rubber mixture 0.063 mm per landing
 
There are no differences between the previous running
 
surface mixture and the soft rubber mixture with regard to wear.
 
Average number of landings achieved
 
Previous running surface
 
mixture: 158.6 landings
 
Soft rubber mixture. 157.8 landings
 
3.4.3 Sensitivity to Cuts
 
No obvious differences could be detected in sensi­
tivity to cuts between the two rubber mixtures.
 
4. Influence of Runway Grooves on Landing Efficiency 

*(Grooves (macrotexture) have no influence on rubber
 
wear)
 
After runway 14/32 was put into operation in April 1976
 
landing efficiency dropped by about 8%, as compared to the same
 
time period in the previous year. *(As result of the micro­
texture) During the same period of the following year landing
 
Q 
/6 
efficiency increased again by 5% so that it stands only
 
slightly below that before the grooved runway was put into
 
operation.
 
Comparison of yearly efficiencies shows no differences be­
tween 1975 and 1977. It can be assumed that the temporary drop
 
in efficiency in 1976 was probably due to the roughness of the
 
new runway surface and not due to the grooves, resp. the Chevron
 
Cutting.
 
5. Runway Texture with Brush Finish
 
In the attempt to reduce the amount of Chevron Cutting a
 
surface texture in the form of a brush finish crosswise to the
 
touchdown direction was provided over a length of 1200 m during
 
the construction of runway 16/34.
 
During the first phase of operation of this runway the
 
previous "Chevron Cutting" characteristic changed for one of
 
the rubber-capping fabrics (Thompson) The breaks become
 
closer, shorter and shallower (see Fig. 15). This effect was
 
not observed any longer after a few days had passed. It is
 
assumed, therefore, that the brush finish texture is quickly
 
filled by the worn rubber and thus loses its effect.
 
6. Tire Defects Because of "Chevron Cutting" 

Defects that are caused by Chevron Cutting are relatively
 
harmless. No complete separations from the running surface or
 
blowouts will result. Only breaking off of rubber or rib sep­
arations above the reinforcement layers can happen (see Fig.
 
14).
 
The following defects were caused by Chevron Cutting so far
 
/7 
9 
L -
A/C Gear Fabric Description of Defect
 
DC-10-30 NLG Mader Rib completely separated
 
DC-10-30 NLG Mader Rib separated by 60 cm (Fig 16C)
 
DC-10-30 NLG Mader Rubber breaking off (Fig. 16A)
 
B-747 MLG Kleber Rubber breaking off (Fig. 16B)
 
7. 	 Evaluation for Susceptibility to "Chevron Cutting" of
 
Rubbercapping Fabrics Now in Use
 
The extent of Chevron Cutting differs for the various
 
rubber capping fabrics according to the different rubber mix­
tures. It could be observed, for instance, that breaks at the
 
running surfaces are shorter for natural rubber mixtures than
 
for synthetic mixtures (Fig. 15). Chevron Cutting occurs with
 
different intensity at all types of aircraft, resp. tire dimen­
sions.
 
The evaluation in Table I allows a survey of the extent
 
of Chevron Cutting for different rubbercapping fabrics and dif­
ferent dimensions. The evaluation is related to the number,
 
resp. frequency, of Chevron Cuttings and not to the dimensions
 
of the breaks.
 
B-747
 
Re- DC-9-32 DC-9-33/51 DC-8-62 DC-10-30 MLG/
 
treader MLG NLG MLG NLG MLG NLG MLG NLG NLG
 
MAEDER 0 0 O-X 0 X 0 X-XX X XX
 
THOMPSON X 0 X-XX 0 XX 0 XX X XXX 
GOODYEAR 0 0 0 X 0 X-XX X -
Chevron Cutting None = 0, Slight = X; Medium = XX, Heavy = XXX
 
10 
8. Summary/Conclusions
 
8.1 THOMPSON-tires
 
--Chevron Cutting can be greatly reduced with the fiber­
glass-rubber mixture.
 
--Based on wear measurements 20% lower efficiency is ex­
pected for this rubber mixture than for the previous
 
one.
 
--Resistance to damages through cuts appears to be worse,
 
based on visual inspection.
 
8.2 GOODYEAR-tires
 
--Chevron Cutting can be eliminated with spiral wrap
 
rubbercapping.
 
--The cord threads in the circumference of the running
 
surface do not reduce landing efficiency appreciably,
 
according to wear measurements.
 
--Resistance to damages through cuts seems to be more
 
positive.
 
8.3 MAEDER-tires
 
--No differences were noticed between the softer mixture
 
and phe previous running surface mixture, as regards
 
Chevron Cutting, wear and sensitivity to cuts.
 
--The extent of Chevron Cutting is generally smaller for
 
Mader running surfaces than for the previous Thompson
 
cappings.
 
11 
8.4 General
 
Chevron Cutting occurs in different forms depending on the
 
type of tire and the rubber on the running surface. Hardest
 
wear of all tires is shown by the main tires of the B-747.
 
Tires capped by Thompson are more affected than any of
 
the other rubbercapping fabrics.
 
8.5 Defects
 
Four defects have occurred up til now, in the form of 2
 
rip separations and 2 breakouts of the running surface.
 
Three defects occurred on DC-10-30 tires that were capped
 
by the Mkder Company (Figs. 16A, 16C). One defect occurred on
 
a new B-747 tire from the Kleber Company (Fig. 16B).
 
9. Suggestion
 
9.1 THOMPSON
 
Lower efficiencies are expected for the rubber mixture re­
inforced with fiberglass, according to wear measurements.
 
Since this rubber fabric is still purchased from the USA 

an increase of 10% in capping costs is to be expected. In case
 
of an eventual switch to a European source of supply the in­
crease in price would amount to between 3-5%, according to
 
Thompson estimates.
 
It is suggested that this rubber mixture not be used
 
because of the financial disadvantages involved. Of all
 
/9 
12 
aircraft tires and capping fabrics used the B-747 running
 
surfaces by Thompson are the most seriously affected by
 
Chevron Cutting. It is suggested that this type of tire be
 
capped with natural rubber or some improved rubber mixture, for
 
the time being.
 
9.2 GOODYEAR
 
--Because positive results have been achieved with the
 
spiral wrap tires and no price increases are expected for the
 
moment, it is suggested that this construction be continued
 
for the B-747. After sufficient experience with it the intro­
duction of this construction may be considered for other types
 
of aircraft.
 
9.3 MAEDER
 
--Since no better results were achieved with the soft
 
rubber mixture it is suggested that this mixture not
 
be introduced.
 
--It is suggested that the M~der Company make some changes
 
in the rib configuration of the rubber mixture on this
 
type of tire since only M~der-capped DC-10-30 NLG-tires
 
suffered defects from Chevron Cutting.
 
13 
ORINhAL PAU-"O)W POOR QUALrry 
Fig. 1 	Runway 14/32 Touchdown Zone
 
Tire cross-section
 
Fig. 2 	Runway profile. A B-747 tire with 13.35 kp/cm2 tire
 
pressure is pressed about 1.4 mm deep into the groove.
 
14 
Fig. 3 Chevron Cutting occurs at the touchdown surface when
 
the stationary tire glides over the groove edges.
 
1s
 
Fig. 4 	"Spiral wrap" construction contains cord threads in the
 
running surface rubber which are wound in the direction
 
of the circumference.
 
. .. r o, 7' 	 -. ---
Fig. 5 THOMPSON--normal mixture with typical Chevron Cuts.
 
16 
OF pO0I, QALM
 
compound with typical Chevron 
Cuts.
 
Fig. 6 THOMPSON--Fiberglass 

17
 
Fig. 7 THOMPSON--Normal mixture typical appearance.
 
18 
Fig. 8 Fiberglass compound typical appearance.
 
19 
'TQfNAL PAGE I8 
WOR QUAL1TW 
Fig. 9 GOODYEAR--normal construction with typical Chevron
 
Cutting.
 
20 
Fig. 10 	 "Spiral Wrap" construction, typical appearance of a
 
worn-out tire. No Chevron Cutting appears on this
 
tire.
 
21 
-"6 UALIS
 
Fig. 11 MAEDER--normal mixture typical appearance of worn­
out tires. 
22 
Fig. 12 MAEDER-soft rubber mixture typical appearance of
 
worn-out tires.
 
23 
ORIGNAL P&G%...
 
o poOl QUAJ-ff 
Fig. 13 MAEDER--normal mixture with typical Chevron Cuts.
 
24 
Fig. 14 MAEDER--soft rubber mixture with typical Chevron Cuts.
 
25 
OfRINoA PAGE IS 
OF POOR QUAUTrl 
Fig. 15 This form of Chevron Cutting could be observed during
 
the run-in phase of runway 16/34, which had been
 
equipped with a brush-finish surface texture, but only
 
on Thompson cappings.
 
26 
Rubber breakouts caused by Chevron Cutting
 
Fig. 16A (DC-10 NLG) Fig. 16B (B-747)
 
27 
ORIGINAL PAGE IM 
OP POOR QUALITY 
Fig. 16C Chevron Cutting is the point of origin for a rib
 
separation (DC-10 NLG).
 
28 
Fig. 17 THOMPSON--natural rubber 
mixture mit shorter breaks.
 
L pAGE ISoulGt 
oF r Q 29
 


Chevron cutting: Experiment with new runway mixtures

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server