Controlled release device that retards motion by extruding or drawing a tapered ductile pin through a die will control launch vehicle motion at liftoff. The device prevents the damaging dynamic stresses that are imposed on the vehicle when it is instantaneously released at full thrust

Burcham, T. W.

English

NASA Technical Reports Server

December 1966	 Brief 66-10628 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Controlled Release Device Prevents Damage from Dynamic Stresses 
--	 - 
Structural  
Skin 
of 
Vehicle
J (0')
Pivot Joint 
Die Fitting 
Longer 
Tapered 
Die Aperture Surface 
Shorter Tapered 
Tapered Deformable 
Surface Pin
The problem: 
To develop a device that will control launch ve-
hicle motion at liftoff. Vehicle liftoff from a launch 
pad or platform involves three steps: igniting the 
vehicle's first stage, restraining the vehicle with hold-
down arms until the rocket engines attain full thrust, 
and releasing the vehicle by disengaging the holddown 
arms. Instantaneous release of high thrust vehicles 
imparts a large transient load to the vehicle that can
rupture propellant tanks and damage the vehicle's 
structure and equipment. 
The solution: 
A controlled release device that retards motion by 
extruding or drawing a tapered ductile pin through a 
die. The device prevents the damaging dynamic 
stresses that are imposed on the vehicle when it is 
instantaneously released at full thrust.
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights. 
https://ntrs.nasa.gov/search.jsp?R=19660000626 2020-03-11T17:46:03+00:00Z
How it's done: 
The controlled release device consists of a pivot 
joint, die fitting, and tapered deformable pin. The 
pivot joint is linked to the die fitting and bolts to the 
structural skin at the base of the vehicle. The pin, 
made of ductile steel, has a cylindrical cross section. 
The double tapered segment of the pin fits within the 
die fitting; the straight shanked segment of the pin 
passes through the die's aperture and extends outside 
the fitting. 
The aperture of the die is tapered with the small 
end facing outward. The shorter tapered surface of the 
pin seats against the aperture. Since the minor diam-
eter of the aperture is smaller than the major diameter 
of the pin, the ductile pin will be deformed when it 
is pulled through the aperture. Resistance to move-
ment diminishes as the pin is pulled through the die 
because the longer tapered surface of the pin has 
a decreasing diameter. 
Notes: 
1. Vehicle energy absorbed by the controlled re-
lease device is determined by pin diameter and 
by angles and lengths of the pin's tapered surfaces. 
The time required for complete passage of the 
pin through the die is determined by the length 
of the longer tapered surface. Thus, various pin 
configurations can be used to control release time 
and energy absorption.
2. While using a pin-and-die device to limit loads 
and absorb energy is new, this type device has 
been used for many years to draw or extrude wire 
from ductile pins. Because of this previous experi-
ence, the controlled release device is relatively 
easy to design. It is also easy and inexpensive 
to manufacture, reliable, and easily attached to the 
vehicle. 
3. This device could be used as a fail-safe system 
for tension loads, a deceleration device for eleva-
tors, a shock absorber for space-vehicle landing 
gear, and other applications when it is desired 
to limit loads to specific values or to absorb given 
amounts of energy. 
4. Inquiries concerning this invention may be di-
rected to: 
Technology Utilization Officer 
Kennedy Space Center 
Kennedy Space Center, Florida 32899 
Reference: B66-10628 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: T. W. Burcham 
(KSC-66-14) 
Brief 66-10628	 Category 05


Controlled release device prevents damage from dynamic stresses

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