CORZERO
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Nope. That was my butt crack clenching shut...
Adrian
Ah, makes perfect sense now
Nope. That was my butt crack clenching shut...
Adrian
It works, but for it to be of any safety value, the programmed target values have to provide a pretty narrow margin of success.
I talked with Keith a few years ago about using a look-back approach (i.e., rocket must have been within the tolerance for the past few seconds at least), but I don't believe this was ever implemented.
Yes, I did something about this -- if you have a 'delay after other events', then it will check all of the conditions every 100ms and if they ever go 'false', then the ignition is inhibited. So, if you want to fire 10 seconds after motor burn out, then just set 'delay after other conditions' to 10 seconds and 'tilt angle less than' to 20 degrees and if the airframe ever tilts more than that during the 10 second delay, then staging will be inhibited.
Mercury switched staging is specifically prohibited by the Tripoli Safety Code.
Many clubs are forbidding them on their own. I know the 2 NAR clubs I launch with don't allow them any more.But NOT by the NAR Safety Code, either for Model Rockets or HPR.
Dave F.
Many clubs are forbidding them on their own. I know the 2 NAR clubs I launch with don't allow them any more.
I'm sure there are a few "clubs" with different rules. However, that is not "official", either when flying with an NAR Section, OR "on your own".
The NAR still permits the use of Roller Switches, too, unlike Tripoli . . .
BTW - The use of "timed, sheathed fuse" ( not Thermalite ) is not disallowed by either organization. Everything gets lit at Liftoff and the "timing" is controlled by Burn Rate, selective sheathing, and length . . . "Old School" !
Dave F.
Neither organization has to prohibit fuse. NFPA requires electric ignition:
“remotely controlled, is electrically operated, and contains a launching switch that returns to the “off” position when released.”
Like flashbulb ignition, mercury switch airstart initiation has become an obsolete technology, with much better alternatives available at a reasonable price. Starting the timer with a G-switch is fine, but there should be some kind of mechanism for aborting the ignition if you go off-axis...altitude@ignition, velocity@ignition, and/or tilt angle@ignition.
I don't think mercury switches were banned "on a whim". Seems a very well-reasoned and insightful prohibition, where enacted. And the only participation it's stifling is in those who would rather save money than be safe. If that's you, then perhaps staging composite motors shouldn't be your thing.
One of Cris's Quantums is real expensive at $45 for the kit (alt and programming cable), that's less than destroying a rocket due to an off vertical ignition (like point back at the ground).Adding expense, by requiring expensive flight computers to even the smallest and simplest composite-powered, staged models is detrimental to the hobby. Banning things and adding rules and regulations, on a whim, does not address the "big picture" of Rocketry . . . Participation !
Dave F.
Scott,
Mercury switches were only banned by Tripoli, not NAR. I suspect that it was more about being "Green" ( toxic Mercury ), than safety. As for staging BP and APCP motors, I have been doing that, safely and successfully, since the mid-1970's. Note my NAR & TRA numbers . . . I'm no "newbie" !
Dave F.
I think the general consensus stance is that mercury switches are inherently unsafe for any number of obvious scenarios pointed out earlier in this thread. You're leaving far too much to chance with consequences far too great. Even when it was widely used out of necessity we knew it was a bad idea.
If I had been doing it successfully for as long as you have I would consider myself lucky, not safe.
Steve,
Everything IS remotely, electrically-ignited . . . All other igniter(s) are activated either simultaneously or in flight ( 3- Stagers ).
Let me explain, in more detail.
The lower stage motor IS ignited, remotely & electrically . . .
Its exhaust flame ignites the other "delayed igniter" for the upper stage . . .
During first stage burn, the other igniter is burning ( usually sheathed ), inside the airframe . . .
It burns up into the upper stage motor and ignites a few slivers of Blue Thunder and staging occurs ( It is "sheathed" to prevent improper ignition of a core-burning motor ).
The Ejection Charge of the lower stage motor deploys its parachute and the same occurs for the upper stage.
This was routinely done in the "pre-electronics" days of Thermalite.
NOTE : "Sheathing" tremendously increases the Burn Rate.
In the images below, note the Terms "Discontinuous Staging", "Delay Direct Staging", and "Insulating Sleeve" . . .
Here is an example of a rocket that uses "Discontinuous Staging" . . . https://v-serv.com/usr/kits/stinger2.htm ( When you see the pics, note the name "Bill Barber" . . . I flew with him on a regular basis )
Dave F.
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I find it ironic that you’re arguing current safety rules based on a document copyrighted 35 years ago by Jerry Irvine, but I’ve solved it on my end at least. [emoji850]
You are arguing and you are doing it with the CURRENT president of Tripoli by using sources from decades ago claiming "if it worked then why can't I do it now????" I've held this in for a while now but all you do is go around and "boost" about your knowledge and how you know how to do everything and that there is no way what you are doing is wrong or unsafe. If you can't go a day without arguing with someone over the internet then maybe you should get off it and go outside. You have become a nuisance and are acting exactly like a typical know-it-all who thinks they are better than everyone even those who have a position of power.I am not arguing anything
Steve
(1) I am not arguing anything . . . "Non-Electrical" ignition has never been allowed . . . After the initial motor is remotely, electrically ignited, everything else is initiated by it.
(2) Actually, Korey Kline was the initial author and Jerry Irvine "joined in" later.
(3) That document was used because it was the only one that accurately describes the process, whether it was 35 years ago, or not. ( no matter who it was written by )
(4) Tripoli has banned Mercury Switches and Roller Switches . . . NAR has NOT . . . FACT !
Dave F.
Hi Dave,
IMHO Point (1); a spark might cause a few drops of kerosene in a barn to ignite; the kerosene in turn ignites dry hay, which then ignites the barn, but saying that the spark burned down the barn isn't terribly accurate. The spark set off a chain of events that caused the barn to burn down. The ignition of a booster sets off a chain of events. In the same fashion, I think most people would agree that an ejection charge in a BP motor isn't electrically ignited.
Point (2) is immaterial.
Point (3) describes a process but I don't think that validates the idea that the upper stage is electrically ignited, as I mentioned in (1).
Point (4): I don't recall whether mercury switches caused any accidental ignition or other accidents, but I do recall vaguely that HPR Magazine reported on an accidental ignition via a roller switch. Anyone else who remembers this?
Best -- Terry
Trevor,
Respect your elders . . .
Dave F.
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