Just did the test and all matches went, plenty of ‘pop’ but 4-40 shear pins
didn’t go. So, hatch didn’t open – no deployment. This was with 0.7 g BP. I
don’t want to go higher on the BP, so I’m going to have to modify (weaken) the
4-40’s or change the orientation of the shears. On the curved 5.5” airframe
they are presently at the top and bottom of the hatch. The burn pattern
suggests that the sides maybe a better placement for shears. So, maybe 2-56
nylon shears there. I have to review the video and take a break to think this
through.
Richard
From: David Smith<mailto:davew6dps@xxxxxxxxx>
Sent: Tuesday, January 24, 2017 12:06 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: Resistance for Electric Matches
With three in series, if one burns open the other two may not light.
Ensure that however you wire it the power source can promptly provide enough
current to each match.
You should do all testing with the exact power source and wiring that will fly.
I have seen several people ground test with teat leads and then have issues
with smaller wiring in the actual bird.
Ideally you should also have the same switches and same equivalent resistance
found in your altimeter.
David Smith
NAR 78668, TRA 15803
Amateur Extra, W6DPS
