Reasons why you do EX??

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edwardw

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I had a chat with a couple club members who do EX and we were discussing why we did it. Our group was split 75/25. 75% of us were for the science of it and really didn't care if we flew them in rockets. 25% were because they like making their own motors and because of the lower cost. So why do you do EX?

Edward
 

DynaSoar

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Because I want to be able to do things that aren't going to be allowed under club/group rules that require motor certification. I want to fly liquid fuel motors.
 

edwardw

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We have a guy in our club who just started a N2O/JP-4 Motor. So far it is pretty sweet.

Edward
 

Chuck Rudy

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First off the science is interesting and intriguing, and the absolute total control over the motor makes for a lot of allowances, ideas, motor profiles and colors. The expense makes it possible to do static tests in the backyard (which the neighbors just love), something which is not cost effective with commercial motors. And it has a much more intrinsic and easy going crowd.

So it's:

Science
Control
Expense
Great People

Now.........which box do I check?
 

MarkABrown

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I do it, definately, for the science of it. I find it fascinating controlling the thrust profiles and the smoke and flame color.
 

r1dermon

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indeed. its cool stuff to be able to control the thrust of any given motor. especially when you can make a motor burn forever with small thrust and then make the same size motor burn for like half a second with HUGE thrust. its cool. and all the stuff is relatively easy to get.
 

Johnnie

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Unfortunately I am a minority, as my interstes lie in potassium nitrate composite propellants (KNCP) and hybrids, and all of the ex'rs around me are AP addicts. So for me the science of amateur experimental whether it is "candy" hybrids or AP is all the same. But with KNCP, I find the same rocket science comes at a fraction of the cost of the AP propellants. The hybrid work I am venturing into I cannot speak for as I have very little knowledge of it yet, but I will say that paraffin is pretty cheap too...

The people at these launches are great. They are a different breed. The wealth of information at these launches is priceless.

I rode middle ground on the poll, but could have checked them all and then some.
 

DPatell

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I do it mainly because I can do things with EX that I can't do with commercial. For example, I have a pink motor ready to fire. I can go down in my basement at my discretion and just mix a motor, of any variety my chemicals allow.
Also, I have two lathes that I can make casings on. I can use these casings at EX launches, and that definately saves me money.
So I enjoy the science and variety of the chemical formulations of the propellent, and I enjoy the machining and the money saved by making my own casings. I'm split.

And with time the chemicals will pay for themselves, especially after this AT price increase. EX is the way to go.
 

cdma77

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Originally posted by DPatell
I do it mainly because I can do things with EX that I can't do with commercial. For example, I have a pink motor ready to fire. I can go down in my basement at my discretion and just mix a motor, of any variety my chemicals allow.
Also, I have two lathes that I can make casings on. I can use these casings at EX launches, and that definately saves me money.
So I enjoy the science and variety of the chemical formulations of the propellent, and I enjoy the machining and the money saved by making my own casings. I'm split.

And with time the chemicals will pay for themselves, especially after this AT price increase. EX is the way to go.
Dan,

I hope you are not mixing propellant in your basement ! That is a big no, no ! If you have some kind of fire you could burn down your home.

Jeff
 

Bowhunter

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Originally posted by cdma77
Dan,

I hope you are not mixing propellant in your basement ! That is a big no, no ! If you have some kind of fire you could burn down your home.

Jeff
EEEK:eek: I dont think that would be covered under your Home owners Insurance
 

r1dermon

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it depends on the propellent. candy propellent is quite safe. but if you're mixing BP, some extra precautions should be taken. as long as you have good ventilation and you mix in small quantities and store in small quantities(if you store at all) then you should be all set.
 

edwardw

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Any propellant mixing in a basement is not a good thing. Earlier this year we had a guy burn down his house and kill himself while mixing propellant. He was in his garage, had a small fire that ruptured a gas line and then his house exploded and burnt down. Not a good thing.

Edward
 

Rocketmaniac

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I voted for "Cheaper" but I like it because all of the above. I'm just getting into it, but so far it's way cool..........
 

rocwizard

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I do it for the science of it. That's waht first got me into it. All the other good stuff that comes with i.e. the great people, reduced costs, etc. are a bonus. Trying to be like Frank, I take motors to the edge.:D
 

DynaSoar

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Originally posted by edwardw
Any propellant mixing in a basement is not a good thing. Earlier this year we had a guy burn down his house and kill himself while mixing propellant. He was in his garage,
His garage was in his basement? No wonder he blew himself up. He wasn't very bright.
 

daveyfire

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Originally posted by Ryan S.
No one can be like Frank.
Who would WANT to be?! :p

Though I do give him credit: there is only one Frank Kosdon. The rest of us have to obey the laws of physics.
 

r1dermon

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there are some mixtures which are a LOT more prone to self-ignition. DDT, violent deflagrations, etc...things like that should never ever be mixed in your basement, and if you HAVE to mix them(which in rocketry, most of the time you dont need something that will flash over or DDT) then they should be mixed on a piece of paper in less than 1 gram increments. seriously though, i've experimented with these mixtures in rocketry....they dont work at all. not even a little bit. so its pointless to try. heh. sugar is where its at.
 

DynaSoar

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Originally posted by cdma77
Dan,

I hope you are not mixing propellant in your basement ! That is a big no, no ! If you have some kind of fire you could burn down your home.

Jeff
Obviously the same can be said about any other part of the house.

So where *should* people mix propellant?

Of course it can be unsafe. It's rocket fuel. That means it needs to be done in a safe manner, not that it shouldn't be done.

If people spent as much effort telling each other how to do things safely as they spent warning them about the obvious dangers if they don't, the don't wouldn't happen. Except to people who have a garage in their basement, even if only in the figurative sense. Figure: this hobby was started because Stine knew people were going to try to build rockets, and he wanted them to have a safe way to do it.

Basement: You must have adequate ventilation. If your basement doesn't, make yourself a hood. If your fumes might be flammable, such as light hydrocabons, it needs to have an explosion proof motor. If your fumes might be heavier than air, you'll need an intake at floor level. Keep anything else flammable away from the area. A good work hood (suction or no) should be built along the lines of the BATF type 4 magazine. Check your homeowner's insurance to see if doing this voids it. Check with your fire marshal to see if this is illegal. Even if it isn't, do your fire department a favor just in case, and post warning signs appropriate to the kinds of chemicals used on the outside of the house nearest where you work/store them. You may be fully aware of the danger and are willing to do it, but it's not fair to the fire department to expect them to walk into a situation unwarned. The wrong fire fighting technique, and they could make things worse.

A very good hood for both chemical and painting use can be made from an old camping tent. Set it up (hung from the ceiling if necessary), and run some plastic air vent tubing (well sealed) from the tent window to the basement window. Install a fan in the window, connect the vent, and have at it. If the tent is old and leaky, a layer of plastic sheet, even the cheap stuff, will seal it well. the fan should be a squirrel cage with the motor outside the cage, run by a belt. Do not use a fan with the motor in the middle. You'll be pulling fumes right across the motor, and unless it's explosion proof there will be trouble. By the way, explosion proof only means it won't explode outside its case. It doesn't mean it won't explode inside its case. If you're setting this up in your basement, and you have a garage down there, you probably need to know the fan should be set to blow OUT.
 

Chuck Rudy

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Originally posted by DynaSoar
His garage was in his basement? No wonder he blew himself up. He wasn't very bright.
If his gas line (and meter as is usually the case) were run through the garage he would have been safer in the basement. That natural gas is nasty stuff. Both kinds. ;-)
 

rstaff3

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Well, rather than just provide a dry comment, I should say what I'm up to. I just recently started building sugar motors. I do it because it sounded like fun, I'm not much of a chemist and will stay with what's proven, so its not so much the hard science. Building is fun, but I think I'll like the results more than the process. I think I'd like to get into machining and may take a class at a community college. Finally, the motors will be quite inexpensive, even if you don't but the cheapest materials. However, cost isn't my motivator either.

Where I mix - in the back yard on a concrete slab, with body protection. I know people mix this stuff in their kitchen...but not me (am I smart, cautious, or chicken? - you can decide). This will limit me to calm days with temperate weather, but I'm not planning to build huge numbers, so I can bide my time thru the winter, for instance.
 

Ryan S.

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Originally posted by r1dermon
you HAVE to mix them(which in rocketry, most of the time you dont need something that will flash over or DDT) then they should be mixed on a piece of paper in less than 1 gram increments.

when would you ever have too mix explosives? Blowing up mailboxes? Houses? Carrying out Gang hits?
 

r1dermon

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explosives? technically BP is an explosive...so is anything that expells volumes of gas as it deflagrates. sugar propellent...thats an explosive....im saying something that has a ton of energy inside of it...take ammonium perchlorate for example...a common oxidiser in rocketry. that stuff isnt a joke. it makes great rocket fuel, but it can also DDT. so if you're into composite propellent making, and you're not going for the sugar scene, then you would be mixing these types of chemicals.

unless you're absolutely sure about something, and you have knowledge and experience with it, i would research it before trying any experiments or mixing with it. things like that can cause a lot of harm...

ryan, are you implying that i blow up mailboxes to have fun? if so i do take offense to that. you can PM me with any concerns that you have.;)
 

edwardw

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Originally posted by DynaSoar
His garage was in his basement? No wonder he blew himself up. He wasn't very bright.
That's not what I said at all. I said he was in his garage. It was a three car garage will all doors open. From what I've heard he was in his driveway with his mixer mixing a batch. He lived in a remote area where your next neighbor is quite a ways away. Somehow on his table the propellant ignited, then ignited some grains nearby. A couple skittered into his garage and started it on fire. Then a gas line ruptured from the fire.

But, as for gas lines *most* new construction is the yellow plastic tubing, which isn't great for a house fire. I know with the houses we build you can ask to have the iron pipes if you want, but our subs use the yellow plastic tubing. If your in a basement usually you have a water heater and furnace, so there are also gas lines there....but an enclosed space which is probably more dangerous.


Edward
 

Johnnie

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I have read McCreary's book twice, and will re-read this winter. It is a good book, I can't wait till his new one hits the stands.

I mix in an outdoor shop. It is built on a slab, and is sheltered with tin and plywood. It has plenty of ventilation, and double door escape route.

Heating "candy" might be my only gatcha, as far as keeping a heads-up in place. My epoxy propellant would take a blow torch to ignite inadvertantly. My biggest worry with it is the red iron oxide stains everything.

Safety procedures are always practiced / observed when I mix. Every move I make is logged into a notebook so it will make good reference material in future work.
 

MattEx

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Yep, agreed, Experimental Composite Propellant is a good read.

I do EX because of the variety of different effects and motor configurations I can create. Pretty much, you are limited only by your imagination.

With EX you progress pretty quickly too...
I started off with Sugar propellants, became bored with the same old white smoke, moved onto AP/Silicone, which had nozzle slagging problems, then very recently moved to AP/PU. No, not HTPB, you can't get it in NZ :( .

Check out this photo of a motor I fired yesterday, with my "SupaBlu" formulation - 340Ns total impulse, 435N average thrust ... all in a nice neat 3 grain 38mm package :D .
It was pretty crazy.. :) .
Now i'm faced with the desicion of whether to fly it not :) . I'm not worried it CATO'ing or anything like that, i'm more worried about whether the rocket i'll fly it in will shread or not ;) .
 

Chuck Rudy

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Originally posted by MattEx

Check out this photo of a motor I fired yesterday, with my "SupaBlu" formulation - 340Ns total impulse, 435N average thrust ... all in a nice neat 3 grain 38mm package :D .
It was pretty crazy.. :) .
Now i'm faced with the desicion of whether to fly it not :) . I'm not worried it CATO'ing or anything like that, i'm more worried about whether the rocket i'll fly it in will shread or not ;) .
Well, there's only one way to find out. You'll either have a cool flight or a REALLY cool flight. Let's give Matt a 5 count! :) ......and keep the camera rolling.
 
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