Where do you do your ejection ground tests?

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GrouchoDuke

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I've only flown with motor ejection charges so far. I'm ready to do my first ground tests on black powder ejection charge separations, but figured setting off mini-black powder cannons in town (Las Vegas) is probably a bad idea.

So, where do people who live in cities go to do their tests? Leave the city limits & let 'em rip?

Thanks!
 
Backyard! Covered in a sleeping bag or so, not usually a big deal.
 
Well, I'm probably going to catch some flack for this, but I do them in my back yard. I live in the city limits of Denver, about 10 minutes on the interstate from downtown. 6' fence all the way around probably helps a little with the noise. I've lived in this neighborhood my entire life (47 years) and know most of my neighbors well.

I'm so used to the general noise 'pollution' I hear on a regular basis (lawn mowers, leaf blowers, power tools, car alarms, etc) that I really don't think the black powder charges I have tested are all that loud. To qualify that statement, the largest rocket I have tested charges in is a 4" diameter airframe, with the largest charge being 2.75 grams. I have resisted doing any tests early in the morning or late in the evening. If I ever do a substantially larger project (Level 3.....?) I would most likely take that to our clubs launch site for testing. I know many of our club members will test at the launch site if their residence doesn't provide a suitable location.
 
Front yard, because the back yard is all patio. Here in the LA area, when you hear something go pop you pretty much ignore it...
 
Here in the LA area, when you hear something go pop you pretty much ignore it...
Heh, that's funny...well, kind of.

I guess I should add on that this is for my 29mm min-diameter rocket. I'm guessing the biggest charge I'll set off with it is under 0.25g. I'm not sure how loud that'll be. Maybe I should just turn on a leaf blower to cover up the sound. :)
 
I questioned the same thing when I started testing, maybe 10 charge tests last year. Luckily my backyard is decent sized with some grass, I try to do mine in the middle of the day or as the sun sets. Also calling out what I am doing and count down eases peoples concerns. Tested my 4in Drago with a full charge well, wasnt bad at all. Make sure your shock cord is attached too.
 
Used to be back yard. After 16 years I've learned my neighbors tolerate me so front yard it is. Haven't had the cops called on me yet lol.
 
I did mine for my L1 rocket in my backyard. It really isn't too loud at all, being muffled by the body tube and the harnesses packed in. In fact, before I did my ejection test, I set off a 1.5g charge out in the open, not contained in a body tube just to make sure my setup works well with no issues. That wasn't louder than a large rock being thrown at my house, it seemed.
 
I do my testing in the back yard. You'd be amazed at how quiet it really is. The pop is muffled by the tube, the dog barf, and the chute. It's a dull thump. I have fussy neighbors, and they don't mind. In the winter, I've done some testing in the basement for smaller diameter charges.
 
The most obvious place possible!

...on the launch pad.
View attachment 309543


Just kidding. Don't. :)


In all seriousness, I do them in my backyard. Put some sheets out (you can get sheets for super cheap at the local thrift store) if you're worried about scratching your paint job.

I live 200 yard from hunting land, so a massive BOOM doesn't tend to bother anyone.
 
The most obvious place possible!

...on the launch pad.
View attachment 309543

I had something like that happen once. So, I now ask others to move away when I arm the altimeter.

I did one ground test in my front yard and almost had something bad happen. I had used a motor adapter with a round piece of wood in front of it to seal off the motor mount. But, my motor retention didn't hold up. The adapter shot out of the back of the rocket and hit a curb which prevented it from hitting our car in the driveway. If it had hit the car, it would have left quite a dent. So, when doing a ground test, make sure there's nothing to be damaged in line with the front or back of the rocket - just in case.

-- Roger
 
I do my testing in the back yard. You'd be amazed at how quiet it really is. The pop is muffled by the tube, the dog barf, and the chute. It's a dull thump. I have fussy neighbors, and they don't mind. In the winter, I've done some testing in the basement for smaller diameter charges.

Wow. You're not married are you? Or is your basement EXTREMELY well ventilated?
 
Thanks for all the comments guys. Good point about motor retention. I'm friction mounting the motor in this rocket, so this will be a good time to test that too.

I thought about doing it in the garage, but I'd probably get a wife veto on that. We have tiny yards here in Vegas & the lady behind us is really fussy...and she's always home. I'll probably skip doing it at my house, but a local park might work. It's about a 30 minute drive to the nearest dry lakebed where I fly, so it'd be nice to keep the testing a little closer.
 
Thanks for all the comments guys. Good point about motor retention. I'm friction mounting the motor in this rocket, so this will be a good time to test that too.

I thought about doing it in the garage, but I'd probably get a wife veto on that. We have tiny yards here in Vegas & the lady behind us is really fussy...and she's always home. I'll probably skip doing it at my house, but a local park might work. It's about a 30 minute drive to the nearest dry lakebed where I fly, so it'd be nice to keep the testing a little closer.

Definitely be careful, but a local park might not be legal for such a test, for some reason people get excited over the little stuff.
 
Thanks for all the comments guys. Good point about motor retention. I'm friction mounting the motor in this rocket, so this will be a good time to test that too.

I thought about doing it in the garage, but I'd probably get a wife veto on that. We have tiny yards here in Vegas & the lady behind us is really fussy...and she's always home. I'll probably skip doing it at my house, but a local park might work. It's about a 30 minute drive to the nearest dry lakebed where I fly, so it'd be nice to keep the testing a little closer.

I would think that you are inviting more trouble at the local park than your own property. The 30 min drive to the lake bed doesn't seem that bad. Cost of doing business....

When I bring the rockets back in the house after testing in the backyard, they still smell for a while. So, garage may not be that much worse. Keep the doors open. Any loud boom will just sound like your car backfiring!
 
I have been testing a little home-made deployment device where I just fill the end of the e-match plastic protection cap with Pyrodex P, and it has been successful in the tests so far. Charge is only about 0.1 grams and works fine up to the max I have tested so far which would be equivalent to a 50 pound rocket. At some point, the suspended mass will cause friction/pinching/deflection which will overcome the gasses, and it will fail.
I have been doing this testing in the garage as it is just a "snap", and the smoke is minimal.
 
I have been testing a little home-made deployment device where I just fill the end of the e-match plastic protection cap with Pyrodex P, and it has been successful in the tests so far. Charge is only about 0.1 grams and works fine up to the max I have tested so far which would be equivalent to a 50 pound rocket. At some point, the suspended mass will cause friction/pinching/deflection which will overcome the gasses, and it will fail.
I have been doing this testing in the garage as it is just a "snap", and the smoke is minimal.

Are you saying that's enough to deploy the parachute?
 
Firing a 0.1g charge was one of the tests I was going to do. I didn't know how reliable a charge that small would be.
 
I have been testing a little home-made deployment device where I just fill the end of the e-match plastic protection cap with Pyrodex P, and it has been successful in the tests so far. Charge is only about 0.1 grams and works fine up to the max I have tested so far which would be equivalent to a 50 pound rocket. At some point, the suspended mass will cause friction/pinching/deflection which will overcome the gasses, and it will fail.
I have been doing this testing in the garage as it is just a "snap", and the smoke is minimal.

I'm guessing its a variation of a Z-pard type device. Which is why it uses so little powder for a strong deployment force. iirc AlphaHybrids (TRF user) is working on one too.
 
Even with a piston that's very little.

Yeah, 0.1g is definitely small. My 29MD rocket only has about 6 cubic inches of space in the deployment bay. It pops off with about 8 lbs of force. So even with a good margin of extra BP, it shouldn't take much. My guess was that the most I'd need is 0.25g...perhaps less. Time will tell - testing soon!

I'm guessing its a variation of a Z-pard type device. Which is why it uses so little powder for a strong deployment force. iirc AlphaHybrids (TRF user) is working on one too.

This sounds cool.
 
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I've done 2 - 3 g in my backyard. With all of the laundry packed, the sound is pretty muffled. The ejections can spray out bits of burning matter. I got quite a few small burn holes in a nice synthetic tarp. So be careful about using something nice to muffle the sound or to use as a tarp.
 
Yeah, 0.1g is definitely small. My 29MD rocket only has about 6 cubic inches of space in the deployment bay. It pops off with about 8 lbs of force. So even with a good margin of extra BP, it shouldn't take much. My guess was that the most I'd need is 0.25g...perhaps less. Time will tell - testing soon!



This sounds cool.

A z-pard device is similar to a spigot mortar or a piston launcher, a smaller diameter tube and piston pushing a larger diameter piston, the charge is contained in the tube under the smaller piston, most I have seen have been in medium to large rockets.
 
I've done 2 - 3 g in my backyard. With all of the laundry packed, the sound is pretty muffled. The ejections can spray out bits of burning matter. I got quite a few small burn holes in a nice synthetic tarp. So be careful about using something nice to muffle the sound or to use as a tarp.
Good point, thanks Chris. Bits of fire would make a mess on the new fake turf in my back yard. I did some checking and it looks like it's fine to launch model rockets at our city parts. I couldn't find anything close to "high power rocket pyro testing" in their rule book though. ;)

After all the discussion & thinking through this more, I'm leaning toward just taking the 30 minute drive to a dry lakebed. I'm going to try to do a test tomorrow (Wednesday). I'll let everyone know how it goes. Thanks a ton for all the help!
 
Good point, thanks Chris. Bits of fire would make a mess on the new fake turf in my back yard. I did some checking and it looks like it's fine to launch model rockets at our city parts. I couldn't find anything close to "high power rocket pyro testing" in their rule book though. ;)

After all the discussion & thinking through this more, I'm leaning toward just taking the 30 minute drive to a dry lakebed. I'm going to try to do a test tomorrow (Wednesday). I'll let everyone know how it goes. Thanks a ton for all the help!


0.1 g is not much. You will probably be fine at home. You might have to get a little creative with protection of your turf. Wet it down first or something.
 
How to get the neighbors to call the FBI and BATFE on you in 30 seconds or less.
 
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