Rocket Igniters in the Presence of Radio Energy
-Experiment One: Raw Data -
By Don Irving ([email protected])
Copyright © 1996 Donald J. Irving
Experiment One - Igniters attached to tuned receiving dipoles.
These are the raw results from my testing with Daves igniters attached directly to tuned receiving dipoles. As I have explained elsewhere, this configuration provides a degree of RF coupling that is much greater than the greatest RF coupling one would expect from using radio transmitters at a launch site.
I performed 20 trials in which I transmitted RF carrier for 20 twenty seconds or until ignition occurred. The Trial column enumerates my twenty trials. The Sample column indicates which sample Daves igniter I used. I used a total of six igniters in this test. The Power column tells how may watts of transmit power I used as measured by an in-line PWR/SWR meter. The high power setting on my transmitter produces 50 watts of forward power. The low-power setting produced 5 watts in all trials except one. The Distance column indicates the separation between my 1/2 wave transmitting antenna and the receiving dipole with the igniter. The Duration column tells how long I keyed the transmitter. I transmitted for a maximum of 20 seconds on each trial. In cases where ignition occurred, it happened immediately upon transmitting. I have listed transmit times for these trials as 1 second. The SWR column gives the Standing Wave Ratio of the emitted signal from the antenna as read continuously on an in-line, dual needle PWR-SWR meter. A reading of 1:1 means that virtually all transmitted power radiated properly from the antenna into space. The single reading of 1.3:1 means that a very small percentage of the power was reflected from the antenna back down into the transmitter. The Ignition column tells whether the igniter burned.
Trial Sample Power
(watts)Distance
(ft.)Duration
(sec.)SWR Ignition? 1 1 5 16 20 1:1 No 2 1 50 16 20 1:1 No 3 1 5 8 20 1:1 No 4 1 50 8 20 1:1 No 5 1 5 4 20 1:1 No 6 1 50 4 20 1:1 No 7 1 5 2 20 1:1 No 8 1 50 2 20 1:1 No 9 1 5 1 20 1:1 No 10 1 50 1 1 1:1 Yes 11 2 5 .5 20 1:1 No 12 2 5 .5 20 1:1 No 13 2 5 .25 1 1.3:1 Yes 14 3 7 .5 1 1.1 Yes 15 4 5 1 20 1.1 No 16 4 6 .5 1 1.1 Yes 17 5 50 2 20 1.1 No 18 5 50 1 1 1.1 Yes 19 6 50 2 20 1.1 No 20 6 50 1 1 1.1 Yes
I cannot account for the 7 watt and 6 watt forward power readings on trials 14 and 16. For the other trials using the low-power setting on my radio produced 5 watts. The SWR for trials 14 and 16 were 1:1 as in the other tests. The SWR reading of 1.3:1 on trial 13 is undoubtedly attributable to the proximity (3 inches) of the receiving antenna to the transmitting antenna.
Copyright © 1996 Donald J. Irving
Document URL: http://www.irving.org/rocketry/igniters/proto1.html
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