The only thing that needs to be mandated are the means to make complex multi staged projects as safe as possible
to avoid a severe ground accident.
The only thing that needs to be mandated are the means to make complex multi staged projects as safe as possible
to avoid a severe ground accident.
Sorry for the necromancy, but I have a question on the HEI topic.
Assuming you are using a normal, open Aerotech forward closure. Could you purchase the appropriate size delay insulator from RCS (example: https://www.rocketmotorparts.com/Delay_Insulator,_2938mm/p1577809_7824126.aspx), and then cast your ematch wires in an epoxy plug filling the insulator as the delay grain normally would?
Assuming you strip the wires for say 1/2 the length of the plug facing the "internal/aft" side would there be any reason to expect the plug to leak in flight assuming the motor is built with the normal forward o-rings?
Yes, I know this makes it research.
Also, CJ, what is the black material in your closure pic?
Just a black G-10 disc,[top & bottom] holds the 2 rods perfectly centered in their holes. One rod is wrapped in teflon plumbers tape, then covered with shrink wrap tube to insulate the rod from metal part of closure electrically. Also provides a nice flat surface for nuts to bind against when tightened.
Hole in center is then injected with high temp epoxy [800] to fill the closure cavity. [3/4 in. deep epoxy. Disc gets charred but one with 20+ firings is still fine.
Just finished casting some BKNO3 pellets directly to ignition wire. Used 40 ga nichrome for bridge wire. [same as E-match bridge wire]. Pre tested with 9v battery and lit just fine.
Just a black G-10 disc,[top & bottom] holds the 2 rods perfectly centered in their holes. One rod is wrapped in teflon plumbers tape, then covered with shrink wrap tube to insulate the rod from metal part of closure electrically. Also provides a nice flat surface for nuts to bind against when tightened.
Hole in center is then injected with high temp epoxy [800] to fill the closure cavity. [3/4 in. deep epoxy. Disc gets charred but one with 20+ firings is still fine.
Just finished casting some BKNO3 pellets directly to ignition wire. Used 40 ga nichrome for bridge wire. [same as E-match bridge wire]. Pre tested with 9v battery and lit just fine.
If flame gets through it. Rocket explodes. Violently. Feel free to ask more questions.
Where is the e-match wire going into the system you built? And what brand of epoxy do you use?
Normally casings and airframe sustainer tubes are recoverable. This wasn't found after searching. We don't even have slight confetti pieces to show for it.It's customary to use accurate terms to describe this sort of thing. Just because fire comes out both ends doesn't mean it didn't merely burn very quickly.
This is a 54 CTI closure. 2 matches are used. Pellet passed into top grain has a hole in it.
One match goes through hole/bent upwards to fire into pellet.
2nd match sits on top of pellet, So in perfect world both fire ...from both sides into pellet.
If one fails, other is backup.
View attachment 334483
The 29CTI version both matches [I always use 2] are on top of pellet.
Most users just go with one match..
AT version,I use either a pyrodex pellet pushed into top grain, then Match on top.
For 75's/98's the cores are big,, so match [2] are taped to [1] each side of pellet [BKNO] and lowered into top grain.
All closures are built basically the same & allow for attaching 1 or 2 match wire leads.
Top side the long lead wire goes into a slip fit molex connector on the av-bay.
Our cast pellet onto ignition wire was tested with 9v battery today, [several] and worked great. We even stuck one [tiny 1/3 gram] in a 54 soda can motor today & used the 12v launch system. Again...it worked.
So after getting a bit further, I will figure out casting 2 ignition leads into pellet for redundancy.
The epoxy....wish I could tell ya, but....since this has been an ongoing project & they are being sold, no for now. I will tell ya this, it's for potting electronics in high temp environments ,costs 400.00 gal. and is 1 part heat cure . Closures are placed in a special built oven and cured under several different temp ramp ups for 10 hrs.
The eyebolt is for recovery attachment/threaded into solid aluminum in all sizes. They are all re-usable.
The AT version is single use and requires the special umbilical cord which is large and bulky& costly.
AT standard 54mm tapped closure is 70.00 one of these is 54.00
Thanks for the info. I need to convince myself I can make it all fit in the 38 mm smoke well of an Aerotech closure, but this definitely looks like the most fool-proof way to do HEI. If flame gets through this, your rocket is already confetti.
The only thing that needs to be mandated are the means to make complex multi staged projects as safe as possible
to avoid a severe ground accident. That might include outlawing them from given venues due to fear.
You may not care if you burn yourself up in a mishap but your widow and survivors of anyone you kill or maim
will be gunning for someone, something and $$$$$ from anyone attached to the situation. Peace. Kurt
Some of us are not as enamored with wireless devices as you are, and hope there is no intent to mandate them in the foreseeable future.
Are there plans to produce an AT38 closure for sale? If so, available before Airfest?
That's why I recently am redesigning my HEI for my coaxial motor to use the ET Quantum. I believe that's the safest option currently available for remote arming.
There was a lawsuit against TRA where a woman as spectator was standing 30ft away from a LDRS launch and she got burnt 5% of body by the exhaust. There's a good reason they don't allow spectators around HPR launch pads. Maybe she really didn't understand rockets have hot combustion processes. It was likely her lack of respect and experience around motors that size. They don't let passengers on light general aviation flight lines without crew, because people have walked into whirling propellers which appear nearly invisible when turning. There's a faint red plaque of a reminder of that at every airport. You see a faint outline of an arc. And in New Jersey people get snark when you're from out of state and pump own gas. I told em if you can't pump gas into a car you shouldn't drive. They called me a hick. But I guess someone somehow blew up a car and sued there now it's a law. Touch the metal car it grounds it from static electricity before pumping. Sheesh. I'll never live in Jersey.
We used a magnetic switch on our second multistage rocket this year and never looked back. There's always a risk with anything. Your goal in rocketry or aviation is risk reduction. And you will face daily risks higher than normal.
It was a H123W skidmark with the black CTI delay grain piece completely swapped for an epoxied H118 once fired variant (no powder) drilled through center with igniter and insulated wire inserted through this center hole then epoxied that closure area before inserted into casing.
I don't know how it ended. But here's an external link to a news website that google picks up. Kurt's comment of not wanting to stand next to an L when it ignites made me cringe a tad.
https://www.sandiegoreader.com/webl...t-filed-over-injuries-suffered-at-large-and-/
People like this woman put rocketry at risk. Maybe this media incident is a false rumor. Or spectators really don't know better.
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