It's been an interesting thread, and points out why you REALLY have to understand what you're doing before you start modifying or hacking reload kits. Even if you're some place where NAR/TRA certs don't matter.
And of course, if you don't know what you're doing, then don't do it. And if you THINK you know what you're doing, still don't do it!
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
That's a bit extreme. The safety code offset distances (or even a fraction of them) keep you safe from Cato's.
Once you understand Kn's and throats and pressures one can "kitbash" reloads. One popular combo I have seen is 3/4 Fast and 1/4 Firestarter propellant (with the FS core enlarged 100% for burn time matching).
A manufacturer could even certify such a combo if it became popular (ie tandems).
Jerry
And since on-field core-drilling is now allowed . . . .
:)
What jerry means is; "that rule is inconvenient and should be ignored".
Don't worry jerry, I'm sure eventually you'll understand the difference between a 29mm x 98m F motor and a 98mm x 29mm F motor
Maybe not.
What would be the point? A half ass'd "sort of" firestarter, or a half ass'd "sort of" fast burn motor with crappy performance?
Nay
say
er
Jerry
"That is the precise goal of the trolls (Wallace, Dunakin, "Grayvis", Stein, etc). To spew shit, hope it sticks and to hell with the collateral damage."
- Jerry Irvine
Kevin Trojanowski wrote in news:541oe.27395$iU.5850@lakeread05:
This does show me that there is a substantial change with the additional area of the 2 extra grain ends. Thank you!
Now the question would be;what's the max design pressure of the 24/40 casing? We know that the OP's casing survived(barely?) a much higher pressure using the .104 nozzle with 2 grains.That was 1253 Pc from your calcs.
As Jerry said,it may be "optimizing" the performance for 2 slugs -with a larger nozzle- to keep case pressure within limits.
OTOH,the motor casing life may suffer.
This is an interesting topic.(if not taboo...)
Thereby making it non-linerly more regressive.
Dave Grayvis says I know little about motors :)
Rated 800psi Alcoa 1800psi
Correct.
It did used to be rmr taboo, but is now allowed. When this thread first started I was wondering what folks like former frequent posters like Miller, Bundick, Tavares would say.
Then I thought, they may have evolved too.
Heck, Pratt and Kaplow are here and they are oldtimers.
Jerry
"This theory started out as a joke. The older I get, the more I believe it's the truth.."
You'll have to ask Gary that; he's the one whose answer I would trust.
That may be sheer luck; keep in mind that Gary said it was more like
1500 psi.
Yes, and while it may work for one person, it may cato for another.
-Kevin
Jerry, nobody is saying that the cato will blow your fool head off. It could damage your reload case and ruin at least the rest of your day. If it also destroys a rocket, it could put a guy off HPR for a while, especially if you factor in the public humiliation resulting from your bonehead idea.
Well isn't that special...
Wouldn't that take all the fun out of your evil "kitbashing"?
Alan
Probably.
:)
No, while Jerry was being rather terse, I think he was referring to the fact that optimization often works by adjusting parameters to put performance on limits, minimize safety margins, sacrifice robustness, etc. ISP increases with chamber pressure, so increasing chamber pressure to the limit is Jerry optimal. Resizing the nozzle for typical AT design margins will lower the chamber pressure, and in "Jerry speak" become less optimal.
Your choice. I prefer SU. Jerry does not care about your casing because he is not being harmed by it.
The topic is not taboo, although the practice may be. This is still rec.models.rockets, and the NAR does not condone EX. OTOH, the NAR does allow members to participate in AR (even EX), just not at NAR launches.
Alan
What I find interesting is I post something scientifically correct and you "read into it" lack of care for other people, other people's property and I assume a general sense of evil.
It was HIS case. HE kitbashed it. HE operated it at 1500psi. HE loved it.
Get a grip.
Jerry
rmr =/ NAR
One other, important issue. Anyone witnessing such a debacle may well come away with the idea that rocketry IS a dangerous activity where participants are cavalier about safety and following the safety codes, and where stuff "blows up" all the time.
Rocketry should be about "wow, that was a GREAT flight", not "wow, she blowed up REAL good!".
HE got lucky! LOL.
You both assume rocketry happens in a vacuum surrounding a rare event.
No.
Rocketry is 90%+ successful. Anybody who flies rockets for more than a single cato event or a single RTF flight realizes this.
It seems to me the only good way to make sure your doomsday scenarios do not come to pass (other than shooting the doomsdayers in the head with a large caliber weapon), is to have people FLY MORE ROCKETS so they experience a statistically significant sample.
Just Jerry
"If you don't see that aerodynamics is the more important aspect of rocketry to study, I can only assume you have evil intentions..."
- T.V.M, Apogee Rockets
"Real good!"
Those are not necessarily mutually exclusive. :)
My only concern with this is it makes the motor technically an EX and if something went way wrong, like an injury, it could open a real can of worms. Not that I'm completely without the temptation. I have a G54 I messed up and have been tempted to team the grain with another G54 to make an H motor. I even drilled out the nozzle thinking of the potential for over pressurization due to the greater combustion surface. But for (what should be) obvious reasons I haven't tried actually flying it.
Personally, I think those little reload motors are a great hoot and can put on a heck of a good show at a budget rate. The last launch I went to there was a high school team there planning ahead for next year's TARC. They had one bitching G80 powered 2 stage rocket with all the neat tech toys. Then I walked up with a Fatboy packing a D13. When it punched a hole in the sky they only had one thing to say....."Wow!" Hope they're there when I decide to unveil my one project that'll be packing my HyperTEK J-series in the first stage. I love good theater..... ;-p
Chuck
Impakt wrote:
(unreal flight) - is that the equivelent to an E15? Or???
No, it does not make it technically an EX. An EX motor is home-made propellant. Tripoli EX rules specifically state that you cannot modify a commercial motor to make an EX motor. If you start messing with a commercial motor (basically changing it in ways not described in the manufacturer's instructions), you make a franken-motor that cannot legally be launched at any NAR or TRA launch, sport or EX. You can of course launch it at any private launch, assuming you follow any other government rules such as FAR 101.
(I'm just stating the rules because the TRA EX rules are often mis-understood. I am not saying I agree with them.)
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