Comparison of tightness of 78° machine-countersunk rivets driven in holes prepared with 78° and 82° countersinking tools

MISSING IMAGE

Material Information

Title:
Comparison of tightness of 78° machine-countersunk rivets driven in holes prepared with 78° and 82° countersinking tools
Series Title:
NACA WR
Alternate Title:
NACA wartime reports
Physical Description:
2, 2 p. : ill. ; 28 cm.
Language:
English
Creator:
Gottlieb, Robert
Mandel, Merven W
Langley Aeronautical Laboratory
United States -- National Advisory Committee for Aeronautics
Publisher:
Langley Memorial Aeronautical Laboratory
Place of Publication:
Langley Field, VA
Publication Date:

Subjects

Subjects / Keywords:
Airplanes -- Design and construction   ( lcsh )
Aerodynamics -- Research   ( lcsh )
Genre:
federal government publication   ( marcgt )
bibliography   ( marcgt )
technical report   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographic reference (p. 2).
Statement of Responsibility:
by Robert Gottlieb and Merven W. Mandel.
General Note:
"Originally issued September 1942 as Restricted Bulletin."
General Note:
"NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of advance research results to an authorized group requiring them for the war effort. They were previously held under a security status but are now unclassified. Some of these reports were not technically edited. All have been reproduced without change in order to expedite general distribution."

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 003804978
oclc - 123903827
System ID:
AA00009454:00001

Full Text
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NATI(


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DNAL ADVISORY COMMITTEE FOR AERONAUTICS


WAlR TIME REPORT
ORIGINALLY ISSUED
September 1942 as
Restricted Bulletin

COMPARISCI] OF TIGHfIESS OF 78 MACHKIE-COUNTERSUNK
RIVETS DRIVEN IN HOLES PREPARED WITH 75
AND 820 COUNTERSINKING TOOLS
By Robert Gottlieb and Merven W. Mandel


Langley Memorial Aeronautical
Langley Field, Va.


Laboratory


WASHINGTON


NACA WARTIME REPORTS are reprints of papers originally issued to provide rapid distribution of
advance research results to an authorized group requiring them for the war effort. They were pre-
viously held under a security status but are now unclassified. Some of these reports were not tech-
nically edited. All have been reproduced without change in order to expedite general distribution.


L 252


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NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS


RESTRICTED BULLETIN


COMPARISON OF TIGHTiTESS OF 780 MACHINE-COUNTERSUNK

RIVETS DRIVEN IN HOLES PREPARED WITH 780

AITD 820 COUITTERSI1,TKING TOOLS

By Robert Gottlieb and Merven W. Mandel


In the investigation of machine-countersunk rivets
for aircraft reported in reference 1, it wps shown that
tight rivets are obtained if the rivet hend projects above
the skin surface before driving and that loose rivets are
obtained if the rivet head lies below the skin surface
before driving. In the preparation of the specimens for
the investigation of reference 1, 78 rivets and an 820
machine-countersinking tool were used. The present paper
gives the results of n supplementary study undertaken to
determine whetherr the use of a 78 countersinking tool in-
steid of an 82 countersinking tool w-,ould substantially
alter the foregoing conclusion.

The specimens for this study consisted of two sheets
of 24S-T aluminum alloy riveted together in the form of a
lap joint with two 1/8-inch-dinmeter A17S-T aluminum-
allot- rivets, as shown in figure 1. The nominal height of
the manufactured countersunk head of the rivets was 0.046
inch. The riveting procedure used was that described in
reference 1 as method C, heroin the manufactured counter-
sunk head of the rivot is driven with a vibrating gun while
the shank end is bucked with a bar.

The height of the rivet head above or below the skin
surface before driving is designated hb, positive when
the rivet her.d is above the skin surface and negative when
the rivet head is below the skin surface.

The testing procedure wns the sine as that used in
the investigation of reference 1.












RESULTS


It was concluded in reference 1 that a comparison of
the quality of machine-countersunk riveted joints on the
basis of maximum load alone is not justified; the yield
load as a measure of tightness is a bettor criterion of
th& strength quality of a flush-riveted joint. The yield
load is defined as the shear load per rivet for which the
sheets are permanently displaced an amount equal to 4
percent of the rivet diameter. This definition is arbi-
trary and corresponds, in a measure, to the arbitrary
definition of yieold point commonly specified for aircraft
materials.

The effect of hb on yield load and maximum load is
shown in figure 2 for the three sheet thicknesses uses.
This figure indicates that although the use of the 78
countersinking tool instead of the 820 countersinking tool
increases the yield load slightly, the effect is too small
to be of any prnctic-l importance. The general conclusion
of reference 1, that increasing hb in the positive direc-
tion increases the yield strength, is not altered.

The band of scatter for the test data of reference 1,
obtained with 0.040-inch sheet Pnd rivets with head heights
of 0.064 inch, is shown by dashed lines in figure 2. The
fact that the yield loads for the specimens reported herein
plot within this band indicates that the change to a head
height of 0,046 inch caused no appreciable change in the
yield strength.


Langley Memorial Aeronautical Laboratory
National Advisory Committee for Aeronautics,
Langley Field, Va.



REFEREITCE


1. Lundquist, Euogne E., and Gottlieb, Robert: A Study
of the Tightness and Flushness of Machine-Counter-
sunk Rivets for Aircraft. ITACA FR.., June 1942.



























Figure 1.- Tost specimen.


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