tube launched rockets *edited title*

Could launch abort include it falls over muzzle tube first into ground? I can see a mechanical cotter key to not let someone fly it by lanyard and physical distance from contact plates. But the whole it's lit now abort. .. That gets umm tricker. Or...Maybe if you integrate the contact plates to a car style hobby rocketry launch control box with stand off distances and key abort and multiple switches. Where plates have to contact first then you have to manually turn a key and a toggle. Literally I'm visualizing the tube is replacing a well known 1010 rail.

mbecks said:

I’m not American but I get your point. What differentiates a model rocket launched using a rail or pole and one coming from a tube? Isn’t it still just a model rocket, especially since I have full intent of having a recovery system.

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There’s nothing wrong with launching from a tube.
The two requirements I was concerned about were
1. The requirement to be separated a safe distance from a rocket motor when igniting it. That has nothing to do with your perception of danger and everything to do with being injured by a Cato.
2. The requirement that releasing the launch button stop the current to the igniter.
Both requirements come from NFPA 1122 and 1127 which I think some places in Canada have adopted as part of either building codes or fire codes.

Steve, this is a little off topic, but one of Andrew's questions reminded me of a idea I have considered for a while.

I have a rocket with a three motor cluster. 24mm BP. I'd like to airstart the outboard motors low to the ground, after the core is positively lit - maybe 3-4' up a 6' rod. That's low, slow and small for altimeters. So I'd like to put a non-conductive pull-pin in each outboard pod, on a tether that pulls it out halfway up the rod and completes the ignition circuit. Battery could be switch on at the pad. Sort of like a reverse breakwire.

Does that fit in TRA/NAR safety code? How would an RSO approach it?

Steve Shannon said:

There’s nothing wrong with launching from a tube.
The two requirements I was concerned about were
1. The requirement to be separated a safe distance from a rocket motor when igniting it. That has nothing to do with your perception of danger and everything to do with being injured by a Cato.
2. The requirement that releasing the launch button stop the current to the igniter.
Both requirements come from NFPA 1122 and 1127 which I think some places in Canada have adopted as part of either building codes or fire codes.

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heada said:

In the US, there are NFPA (National Fire Protection Association) rules that most locations have adopted as state laws/codes and thus they have the force of law. Not every location has adopted them though.(Indiana is still NFPA 1125/1127 free!) I'm not sure about Canada as I've never researched it but I'd suggest you should if you're located there. If you're not a member of any of the organizations, you're not held by their rules but there are benefits to joining such as being able to purchase commercial high power rocket motors, the insurance and club launches. If you decide to not join, you must be sure of the laws for your location and you should carry your own insurance.

As for just renaming something just to skirt the rules, it has been done in the past and the results were not good. I would highly recommend against it as it shows you knew it was wrong and tried to bypass the rules. Justice departments normally don't take too kindly to such things. I think the term is premeditated and it only makes things worse for you. You have clear intentions and there are legal methods to do what you want to do, even if they're much more difficult.

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Look up Atkins Accelerator a bump fire stock of sorts and the inventor got shafted on legal fees MG related. He was trying to make a commercial product system similar to the legal fostech, and Franklin rate increasing triggers that aren't machine guns. That inventor had good intentions but the government decided otherwise. Whatever the government approves it must not be changed in any form from that approval letter. Or a lawyer is dying to call it a horrid kind of device worth a lot of jail time. You have to have 100 percent positive intentions that it's a boating flare rocket safety illumination device and not a real weaponize mortar. That inventor of a gun stock wanted a recreational aftermarket toy for a rifle, he tried legally to do it by the processes, something hit a snag, I think it was a design change after approval so minor, and nearly had his life ruined by ways laws are interpreted by lawyers and agencies. If government decides your toy flare launcher is a destructive mortar, ot oh. They might approve it and reverse decisions!!! I don't think renaming a mortar is just gonna fly. That's why I get all henk. If he changes tube length or a bipod config after an approval letter for example then it's not approved anymore!!! It's not him doing any intentional harm. It's how lawyers claim crap is by laws that makes inventors looks bad on bad days. That Atkins guy never wanted a machine gun yet the lawyers determined it was one after approval by actions that company took on implementing design into commercial product. They should have had another approval after changes. That's more ATF US related stuff. But an example of how this kind of topic can go.

Andrew_ASC said:

These are in a lot of commercial rocket assisted boating safety illumination flares using chute recovery. They are in self contained hand held tubes with a mechanical electronically ignition source. So a mechanical movement slider pull to ignite a match. I think these commercial boating rocket flare safety devices would be a direct violation of safety codes because of stand off distances. They appear to use sanitized MPR APCP motors in single use casings. The practical application is boating rescues and survival uses. I'm not okay with the mortar name. You need to call it a automatic boating rocket illumination safety flare device or some gibberish for peaceful intentions only. Make it a safety oriented device. It may be legal but not under any rocketry rules for commercial products. It needs to have parachute recovery. Arming and loading needs to be electronic to meet stand off distances by TRA. NAR. Or CAR. And the idea in general is likely ill advised.

Rocket boating safety flares aren't advertised as mortars. They don't use hobby motors. They do offer high performance. And somehow someone filed a bunch of paperwork to make it legal somehow. I'm not fully knowledgable about the topic. In the US you would need to make it not a destructive device because the ATF gets hyper critical. Basically make it survival lifesaving kind of system and not anything anybody could weaponize. I don't know how the commercial boating flare companies got around the legal definitions.

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There are tube-launched rocket flares that descend under parachute. The ones I have seen have a trigger on the bottom--you hold the tube upright and hit the bottom, rocket fires. I haven't disassembled one to see what kind of motor they use, but it's worth pointing out that they are built and tested to a LOT of high standards. Which makes sense given that it's something that's supposed to save your life. I suppose you could call it a test article but it you don't have a realistic reason to be building and testing a rocket-powered flare (ie you don't have a company name) you're probably going to attract more attention than you want. Most authorities also want you to call in if you are conducting tests so that they don't send rescue resources your way if the neighbors call in a distress flare. That's less of a problem inland, but it's a big deal on the water. There are serious penalties for hoax calls and firing flares could be considered a hoax call.

Andrew_ASC said:

Could launch abort include it falls over muzzle tube first into ground? I can see a mechanical cotter key to not let someone fly it by lanyard and physical distance from contact plates. But the whole it's lit now abort. .. That gets umm tricker. Or...Maybe if you integrate the contact plates to a car style hobby rocketry launch control box with stand off distances and key abort and multiple switches. Where plates have to contact first then you have to manually turn a key and a toggle. Literally I'm visualizing the tube is replacing a well known 1010 rail.

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The easiest way I can think of to do this would be to have a controller rigged up to contact plates at the bottom of the tube and a rocket held at the top of the tube with a cotter pin. Push the button to energize the contacts, pull the cotter pin so the rocket falls and makes contact, and woosh-pop in theory at least. Getting a reliable way to have the falling rocket's igniter leads contact the plates right would be challenging. If anything goes wrong, you release the button and the engine doesn't fire.

Charles_McG said:

Steve, this is a little off topic, but one of Andrew's questions reminded me of a idea I have considered for a while.

I have a rocket with a three motor cluster. 24mm BP. I'd like to airstart the outboard motors low to the ground, after the core is positively lit - maybe 3-4' up a 6' rod. That's low, slow and small for altimeters. So I'd like to put a non-conductive pull-pin in each outboard pod, on a tether that pulls it out halfway up the rod and completes the ignition circuit. Battery could be switch on at the pad. Sort of like a reverse breakwire.

Does that fit in TRA/NAR safety code? How would an RSO approach it?

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I think that would violate the spirit of the Tripoli Safety Code that specifically outlaws roller switches and mercury switches for staging. I also think that most RSOs would have an issue because it would be easy to accidentally set off the outboard motors by lifting the rocket or tangling in a pull wire. Also, if neither outboard motor lit would the rocket be going fast enough to be stable? If one outboard lit, and velocity off the rod is marginal, what’s the result? Those are standard cluster concerns.
I’m not sure how a person could do it safely. Ideally you’d want to detect the acceleration of the central motor and its thrust should be sufficient for stability. You’d need sufficient current to ensure lighting both outboard motors nearly instantaneously. An accelerometer based altimeter might do it but that’s too close to the ground for most launch detection logic I’m familiar with (which isn’t saying much.)
Interesting idea.

I don't even know how, legally those rocket boating flares, get around fire codes in testing, because that's a risk testing those. Maybe they call the fire department up. And test on private land under own insurance??? The dangers are what you legally don't know could be harmful. If I were to make any rocket boating flares for commercial product I'd go ask lawyers first.

Steve Shannon said:

I think that would violate the spirit of the Tripoli Safety Code that specifically outlaws roller switches and mercury switches for staging. I also think that most RSOs would have an issue because it would be easy to accidentally set off the outboard motors by lifting the rocket or tangling in a pull wire. Also, if neither outboard motor lit would the rocket be going fast enough to be stable? If one outboard lit, and velocity off the rod is marginal, what’s the result? Those are standard cluster concerns.
I’m not sure how a person could do it safely. Ideally you’d want to detect the acceleration of the central motor and its thrust should be sufficient for stability. You’d need sufficient current to ensure lighting both outboard motors nearly instantaneously. An accelerometer based altimeter might do it but that’s too close to the ground for most launch detection logic I’m familiar with (which isn’t saying much.)
Interesting idea.

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Isn't the roller/mercury switch prohibition because they are inadequate for using to -inhibit- ignition in a non-vertical flight? They are lousy tilt detectors under acceleration? My proposal is more like a reverse burn-thread. Instead of holding down the rocket, it lights the outboards when broken.

The problems of adequate thrust to weight and asymmetrical thrust are common to any clustered design - pad lit, air lit, or 'rod lit'. The flyer has to design and build appropriate solutions and defend those choices to the RSO. If their defense is poor, they don't fly that day.

I think most altimeter designers cringe if you ask to set a Launch Detect Altitude under 100'. My solution can be armed on the pad after confirming all else is ready. And wouldn't light if the core motor failed to light. The tethers could be short enough to avoid tripping, or it could be done as a single flyer at the pad setup.

My thought, after one of those off-the-wall thoughts Andrew throws around so copiously, would be using the same trick on a compressed air sabot/piston tube tower launched model that lights just -after- clearing the tube. Polaris fashion. (Note, I'm not suggesting finless at the same time

So the biggest problem people are having are safe firing distance and the thought of it being perceived as a weapon, the first one is easy to remedy, the second one is not as easy except that from the start of stated it will have recover and be more like a flare fired from a mortar which is not a weapon. I guess we will see what I come up with. I still am interested in drop firing but since rocket motors don’t actually work like a mortar launch system I don’t know if it feasible.
p.s. Does it help to state that I have fired real mortars and was trained on how to drop fire without blowing my hands off.

mbecks said:

p.s. Does it help to state that I have fired real mortars and was trained on how to drop fire without blowing my hands off.

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No. What you do as a member of the armed forces has zero impact on the regulatory commissions' opinion of the safety of hobby rocketry. Thank you for serving. My hat's off to you. But please don't take away my hobby through foolishness.

Bat-mite said:

No. What you do as a member of the armed forces has zero impact on the regulatory commissions' opinion of the safety of hobby rocketry. Thank you for serving. My hat's off to you. But please don't take away my hobby through foolishness.

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haha I gotcha. I’m leaving this forum for everyone to discuss. I really appreiciate all the imput and comments. Stay posted for an eventual video of what I come up with.

mbecks said:

haha I gotcha. I’m leaving this forum for everyone to discuss. I really appreiciate all the imput and comments. Stay posted for an eventual video of what I come up with.

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please.. take video.. I need a new example of what NOT to do when showing my friends..

mbecks said:

Does it help to state that I have fired real mortars and was trained on how to drop fire without blowing my hands off.

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No - not even related. Many catos happen very low to the ground immediately after ignition. There is no relation to a mortar round flying on a ballistic path. This would be more like a problem with the mortar tube exploding.

Here’s a picture that Final Frontier Aerospace Systems and Technology posted on Facebook that shows what a cato can look like:

I'm curious how the solid fuel rocket motor would like substantially higher back pressure on the nozzle? Normally these nozzles are freely exposed to atmospheric pressure. I have only had advanced fluid mechanics for mech engineering on inkling undergraduate level... In theory we would size supersonic converging diverging nozzles for higher altitudes and lower pressure. You may have a high enough pressure in a mortar style tube design with sabot that the rocket motor CATO's or nozzle performance is severely degraded. Practically I'll claim I'm clueless on how it would do. In theory you start pissing off area throat to area exit and Astar positioning of nozzle design. It's not a drop pin mortar percussion fired with a charge of powder like military does. (I think that's how those work). In military mortar I think the powder burns fast and pressure rises in tube it's designed as such and operates in a principle way like a firearm barrel by physics. Pressure increasing until near complete combustion and velocity of object rising until out of barrel. You have a rocket motor trying to operate in a enclosed tube more like a missile silo or Aa battery... There will be a much higher than atmospheric pressure inside tube once it lights. I don't know how healthy it would be for nozzle. Maybe on LPR motor it won't matter as much as a larger motor. Maybe it's all negligible for a Estes C motor or smaller? I don't know. I would worry it might have same effect as clogging the nozzle with say a rock.

mbecks said:

You guys should see what kids are up to with rockets on YouTube! I will probably carry on. Thanks for the concerns. Anyone have any build ideas for this project?
Heres an example of what popular youtubers are up to: https://youtu.be/DUmIDz5L0O8

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that doesnt make it legal or safe.
but hey, lets snort condoms through our noses and go for the tide pod challenge because its on YT,too.

Andrew_ASC said:

I'm curious how the solid fuel rocket motor would like substantially higher back pressure on the nozzle? Normally these nozzles are freely exposed to atmospheric pressure. I have only had advanced fluid mechanics for mech engineering on inkling undergraduate level... In theory we would size supersonic converging diverging nozzles for higher altitudes and lower pressure. You may have a high enough pressure in a mortar style tube design with sabot that the rocket motor CATO's or nozzle performance is severely degraded. Practically I'll claim I'm clueless on how it would do. In theory you start pissing off area throat to area exit and Astar positioning of nozzle design. It's not a drop pin mortar percussion fired with a charge of powder like military does. (I think that's how those work). In military mortar I think the powder burns fast and pressure rises in tube it's designed as such and operates in a principle way like a firearm barrel by physics. Pressure increasing until near complete combustion and velocity of object rising until out of barrel. You have a rocket motor trying to operate in a enclosed tube more like a missile silo or Aa battery... There will be a much higher than atmospheric pressure inside tube once it lights. I don't know how healthy it would be for nozzle. Maybe on LPR motor it won't matter as much as a larger motor. Maybe it's all negligible for a Estes C motor or smaller? I don't know. I would worry it might have same effect as clogging the nozzle with say a rock.

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Research piston launch systems. Tube launch of model rockets have been done successfully for decades.