I've got some motors that I was asked to fire into the ground and report back the CATO failure rate (or not). I've never done something like this before. I don't have any launch equipment, nor a good place to do it, other than club launches. I might be able to convince one club to let me give it a go, but what is the best and safest way to do it?
How to go about firing some motors into the ground?
- Thread starter Bill S
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Dig a small hole. Put the motor in upside down (nozzle straight up).
Insert igniter. Connect leads. Observe all safe distances.
Five second countdown. Press button.
Insert igniter. Connect leads. Observe all safe distances.
Five second countdown. Press button.
heada
Well-Known Member
Go to Lowes/HomeDepot/etc and get a large clay flower pot and a 50 pound bag of play sand. The pot should be big enough to hold all the sand and still have several inches before it gets to the top. Go out to the middle of your backyard/field/etc and fill the pot with sand. Place the motor in the sand most of the way, nozzle up. Connect your launch controler and go.
Obviously this setup is limited to smaller motors. I would feel safe with 24mm and smaller. 29mm if it is a smaller 29mm. If you're wanting to do it with HPR motors, you'd need a different set up.
Obviously this setup is limited to smaller motors. I would feel safe with 24mm and smaller. 29mm if it is a smaller 29mm. If you're wanting to do it with HPR motors, you'd need a different set up.
I have seen test firing of research motors by placing motor in hole in ground, nozzle facing up. Motor should be snug and buried at least 1/2 way or more.
A quick and simple way of making a hole in the ground - find a dowel, broom handle or piece of pipe or stick slightly larger in diameter than your rocket casing. Locate some soft soil, your flower garden will do. Push or pound your stick into the soil, just less than the length of the motor. Remove stick. Proceed as instructed above, nozzle pointing up. The ejection charge will automatically remove the spent rocket motor casing at the end of the test.
heada
Well-Known Member
All of these will work but if you think there is a higher chance of a CATO and you need to examine the parts post failure, the sand is a good option. It'll capture any parts and it's easy to sift through. A hole in the ground would require you to dig a bigger hole to get parts post failure and then sifting through dirt is harder to do.
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NOTE: This was back in the days before I had a computer, and could have asked for help with a MESS report...
One method that I used was to plant a dowel that fit inside the suspect motor (an Estes D motor) into the ground. After fitting the motor to the top of the dowel, I launched it (upside down of course). For an encore, it projected itself over 100 feet up (eyeball calculation) when the ejection charge went off. AWESOME!!! (The motor would have worked perfectly, don't know what caused the others to explode).
One method that I used was to plant a dowel that fit inside the suspect motor (an Estes D motor) into the ground. After fitting the motor to the top of the dowel, I launched it (upside down of course). For an encore, it projected itself over 100 feet up (eyeball calculation) when the ejection charge went off. AWESOME!!! (The motor would have worked perfectly, don't know what caused the others to explode).
I like the idea of a large flowerpot full of sand, but it may be a tad heavy to transport to a launch site along with my usual stuff.
It probably would be a bad idea to do it in my backyard as the neighbors would be sure to call the police, etc.
The motors in question are 18mm.
I actually don't have any launch equipment so far, as all of my launches have been at clubs (there are no publically accessible lands around here to use).
Hmm... have to think on this.
It probably would be a bad idea to do it in my backyard as the neighbors would be sure to call the police, etc.
The motors in question are 18mm.
I actually don't have any launch equipment so far, as all of my launches have been at clubs (there are no publically accessible lands around here to use).
Hmm... have to think on this.
This should have started with a couple of logical questions.
(1) How large are these motors ?
(2) Are they commercially-produced or "experimental" ?
Dave F.
(1) How large are these motors ?
(2) Are they commercially-produced or "experimental" ?
Dave F.
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Remember, a CATO that ejects a closure is going to have a recoil.
Digging a hole to bury a motor is insufficient if the forward closure blows as the motor case will likely be ejected.
Be prepared.
Digging a hole to bury a motor is insufficient if the forward closure blows as the motor case will likely be ejected.
Be prepared.
I talked to the club I launch at, and firing them there is definitely a no-go, as they use a county park and if some blow up, Karen is sure to complain and lose the club their launch privileges, etc.
I'll just dispose of them, since I have no way to legally send them back to Aerotech anyways.
I'll just dispose of them, since I have no way to legally send them back to Aerotech anyways.
You must have some crappy neighbors.
Typical suburbanites. As for the club, its in the Frederick MD area, and they've already had runins with the Karens using the park and complaining about this and that, even though the club has a permit from the park to use it.
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Karen. The new WMD.
I would have no problem doing this in my own back yard. Unless there’s a cato there’s not much sound from an 18 mm BP motor. Just bury everything but the nozzle. Or use the pot of sand (or even kitty litter) like Aaron suggested.
heada
Well-Known Member
Some smaller motors can be shipped USPS non-hazmat ground *if* the shipping party has a special permit from USPS.
Long story short, Aerotech can ship them non-hazmat, you can't.
Long story short, Aerotech can ship them non-hazmat, you can't.
rcktnut
Well-Known Member
Get/make an 18mm saucer and fly them. Also: Microsoft PowerPoint - 18mm Pyramid.ppt (artapplewhite.com)
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If I'm understanding correctly, you're 1/2 hour from the MDRA club (Gaithersburg, MD) and that is a true independent club, if I understand correctly and they host some of the biggest launches on the East coast. Might want to check them out, as I think they could help.
Sandy.
The club I usually fly with is Narhams (fly in Mt Airy normally), but I did join MDRA so I could fly at Red Glare. I haven't been out there since, because its a nearly 3 hour drive, but I would like to get out there again once the Higgs farm is available (October?).
Just get a long MMT and pound it into the ground. Stick motor in end and let her rip.
lakeroadster
When in doubt... build hell-for-stout!
Just look at the motor, be strong, and say....
Why are you doing this?
lakeroadster
When in doubt... build hell-for-stout!
I was trying to do this at the request of Aerotech. I had a bulk box of 12 motors; 2 flew fine, 2 blew up and wrecked 2 rockets. I reported the problem, and when they told me they were sending me replacement motors, they asked if I could test fire them into the ground to see if any of the other 8 motors blew up or not. Purely for informational purposes, I imagine.
Yep, I think if it were me, a bulk box of Wizards (or similar inexpensive rockets) would be in order. Fly them and see what happens.
I think I am going to just repair the second rocket that was damaged, with a beefed up motor mount, and fly that thing until it dies. Its already got 17 flights on it, so I got my money's worth.
Just have to keep the suspect motors segregated from the replacements.
Just have to keep the suspect motors segregated from the replacements.
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