Evening star., 1904-04-30
THE 1OWA'S DISASTER
REPORT OF NAVAL BOARD OF IN
VESTIGATIoN.
Guns Were Forged for Use Of Brown
Powder-Smokeless Was Used and
Margin Of Safety Passed.

The naval board, consisting of Capt.
Dayton. Commander Fletcher and Lieut..
Dieffenbach, appointed to investigate the
circums tances attending the bursting of
the two eight-inch guns in the starboard
forward turret Of the Iowa, February
last, reports to Secretary Moody The board
finds that in the firing of the guns all the
usual precautions were taken, and an in
terval of twenty minutes elapsed between
the firing of the two guns.
Taking up the history Of the guns which
are known as No. 81 and No. 62, the board
says: THE records show that on the
suits of the physical and chemical tests of
specimens from the forgtngs at the works,
the forgings were all Professionally, accept
ed. except D hoop N-6616, which had one
test bar from one end fall about 100 pounds
per square inch below the elastic limit:
given by the specifications, and which de-
feet was waived by the bureau of ordnance.
1t Is further shown by the records that sub
sequently when the forgings were being
machined at the gun factory defects devei-
oped, the defects being described as nu-
merous sn.aH breaks in the continuity of
the metal and also minute sand and Stag
spots that the forgings were thereupon re-
jected by the factory" :s -.-
Upon a protest by the manufacturing
company it is stated. board was ordered
in accordance with clause In the con-
mended the rejection of certain of the forg-
ings, including the E hoops Of guns 81 and
81 and the F hoop of No. 62 Continuing
| the report says the records show that the
manufacturers asan protested by letter
and through their attorneys, setting forth
statements intended to show that the state
of the art was such that flaws will exist,
as shown by the forgings of other manu-
facturers; that gun forgings for army guns
showed the same defects; that a 4-inch gun
| built up of similar forgings was assembled,
| finished and proved with excessive pres
sure and showed only slight enlargement
| of the chambers after star gauging."
Another board was ordered to examine
and report upon the forgings and the fol-
lowing is quoted from it's report: None
of the S-inch forgings presented for our
inspection are yet machined to finished
dimensions. The defects that are referred
to as existing are common to all In larger
or smaller degree but neither the sand nor
the Stag spots or breaks are serious enough
in the present stage to cause us to rec
| ommend their rejection" 1t Is then SHOWN
that the provisional acceptance of forg-
| ngs included the tubes of guns 81 and 62
| and the E and F hoops of g. TIE bureau
of ordnance approved and recommended ac-
ceptance of the fOrgings with 10 Ie- cent
reduction, the department approving. but
ordering acceptance at contract price.
Smokeless Powder Used
Smokeless powder charges were used, and
it is stated that there was picked up
| after the accident a number Of thin un-
burned strips of the web Of the powder
grain, indicating that the powder burned
| normally up to the point of rupture" The
guns were designed for use with brown
powder. With the adoption of staol<eless
| powder the muzzle velocity was increased
| from 2100 to 2,311 In its conclusions the
| board finds that the S-inch guns of the
| Iowa. so far as material Is concerned.
| were as strong as designed to be that the
af n not fr.ay
| weakening from previous firing, from the
premature bursting of shells in the bore. or
| from excessive pressureS resulting from
| abnormal action of the powder charge. Yet
| the board assumes that the increase of
| muzZle velocity from 2, 100 to 230O while at
| the same time the breech pressure was de-
| creased. reduced the margin of safety along
| the chase too much. with the small mar
! gin of safety remaining. says the board,
| ''any unusual conditions tending to throw
| greater strain on the chase of the gun
would be sufficient to account for the ac-
| cident. Just what these conditions were
| in the case of the Iowa's guns the board
| has been unable to determine; it was prob
| ably a combination in one direction Of
small variations from the normal. The
| assumption that the margin of safety has
| been reduced too much should De verified
| by experiment.
The Recommendations.
'It is recommended that when the mug.le
| velocity is established changed a mini
| mum breech pressure dependent on the de-
sign of the gun, to be produced by the
charge required to give the velocity, 30
fixed, in addition to the maximum Tina.
| more extended experiments be made to
determine the advantages and disadvan-
tages of the present grain powder In COM
parison with other shapes, and to deter
mine the accuracy of the pressure curves
as applied to the powders in actual use"
| ~-e~>