Method demonstrates inexpensive, safe, and foolproof concept for solid propellant rocket motors, using simple handpump to deliver air. Flueric ignition was accomplished using system without stored energy and with complete absence of electrical energy and wiring

Marchese, V. P.

Rakowsky, E. L.

English

NASA Technical Reports Server

November 1974	 B74-10202 
NASA TECH BRIEF 
Langley Research Center
	 C 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Ignition of Sounding Rocket Motors With Hand-Pumped Air 
.
The development of this pneumatic/flueric ignition 
method has demonstrated an inexpensive, safe, and 
foolproof ignition system concept for solid propellant 
rocket motors, using a simple handpump to deliver air. 
Although devised for use with a sounding rocket, this 
system has broad potential applications in all solid 
propellant motor vehicles in first stage ground launch, 
or in upper stages utilizing fluidic programmers. The 
feasibility of the flueric ignitor concept has been 
demonstrated analytically and experimental verification 
of margins of operation have been obtained by igniting 
boron potassium nitrate (BKNO 3 ) and nitrocellulose 
over a range of operating parameters. 
Flueric ignition was accomplished using a system 
without stored energy and with the complete absence of 
electrical energy and wiring. Instead, the flueric ignitor 
(see illustration for schematic view) is based on a two-
component, aerodynamic resonance heating device called 
the pneumatic match. Temperatures in excess of 8000 C 
were generated in closed resonance tubes which were 
excited by a free jet from a simple convergent noz-
zle. Using a nitrocellulose resonance tube, ignition of 
BKNO 3 , a commonly used rocket motor ignition ma-
terial, was accomplished with air supply pressures as 
Vent Tube 
Nozzle	 I I Resonance Tube 
Flow
Propellant 
Ignitor Interface
Propellant Ignitor
Nozzle
Mach Disc	 Conical Wave
Cell 1 -.,-- Cell 2-4,..— Cell 3 
-.4 
Instability Regions 
low as 0.4 MN/m 2
 (55 psig). These tests revealed that 
an operator using a simple hand pump for 30 seconds 
could ignite BKNO 3
 at a standoff distance of 100 m 
(330 ft) with the only connection to the ignitor being 
a piece of plastic pneumatic tubing. 
The pneumatic match consists of a resonance tube 
(hollow cavity closed at one end) and a convergent 
excitation nozzle. The device functions when a free air 
jet emanating from the nozzle induces a resonant 
condition in the cavity. When the flow emerges from 
the nozzle, it accelerates to supersonic speed and then 
readjusts to subsonic speed by compression through a 
shock wave. This process creates a series of diamond-
shaped cells of alternate supersonic and subsonic flow 
which intersect the jet axis throughout the length of 
the jet. A plot of a typical static pressure distribution 
along the axis of the jet is illustrated. It can be seen that 
the pressure rises in the conical fronts of the diamonds 
and drops in the divergent portions to a minimum at the 
intersections. By placing a cavity in certain portions of 
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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the jet, a self-sustaining system of oscillations is created 
by driving the gas in the cavity into resonance. Although 
there is a continuous flow into and out of the resonant 
cavity a portion of the gas remains trapped at the 
closed end where it is subjected to a succession of waves 
producing periodic compression and rarefaction of the 
trapped gas. This periodic compression and expansion 
of the gas within the rigid cavity of the resonance tube, 
produces irreversible temperature increases at the end-
wall of the cavity sufficient to ignite pyrotechnic 
materials. 
Notes: 
I. The following documentation may be obtained from: 
National Technical information Service 
Springfield, Virginia 22151 
Single document price $3.25 
(or microfiche $2.25) 
Reference: NASA CR-2418 (N74-28223), Develop-
meni and Demonstration of Flueric Sounding Rocket 
Motor Ignition 
2. Technical questions may be directed to: 
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Reference: 1374-10202
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
[42 U.S.C. 2457(f)], to The Singer Company, Kearfott 
Division, Little Falls, N. J. 07424. 
Source: Edward L. Rakowsky and

Vincent P. Marchese of 
The Singer Co.
under contract to
Langley Research Center 
(LAR-1 1152)
E 
. 
1374-10202	 Category O3,04,06,07


Ignition of sounding rocket motors with hand-pumped air

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