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Model Rockets (or rather, not stick rockets)


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#1 nordicwolf

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Posted 19 October 2022 - 12:07 AM

Lots of good discussion on stick rockets, balancing or not, two sticks, etc.  Really good info and I appreciate it!

 

Are there any public domain models, either cardboard, maybe 3D printed fins and nose cones, anything, that are designed to be mated with, say, 4oz rocket motors?

 

I read the thread about the guy who made his own motors for Estes rockets.  Has anyone made their own motors then mated them with their own rockets?

 

It sounds involved and complicated, wondering where I might start if I wanted to try that.  Realistically, though, stick rockets may be all I can handle.  Making the motor and attaching to the stick is straightforward.  Making a rocket with tube, fins, nose, etc, would likely be much more involved, but I wonder if anyone has "plans" on how to make a functioning model with perhaps a 1/2" ID homemade motor.

 

Thanks!



#2 Arthur

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Posted 19 October 2022 - 02:43 AM

Look out Apogee Rockets www ( apogeerockets.com)  and YT (Apogee Components) 

 

Most things you could want are there. Most firework rockets are height restricted by the motor and the mass. Unloaded an amateur rocket may well intrude on aviation airspace, and once it's risen to 1000+ feet it's going to land somewhere else.


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#3 Arthur

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Posted 19 October 2022 - 02:47 AM

PS

You'll need to convert all your thoughts and designs to accept the Estes size structure as all amateur rocketry components are designed to that scale, until you reach the high power rockets that need a whole desert just to do tests, and closed airspace to fly.


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#4 dagabu

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Posted 21 October 2022 - 02:51 PM

Lots of good discussion on stick rockets, balancing or not, two sticks, etc.  Really good info and I appreciate it!

 

Are there any public domain models, either cardboard, maybe 3D printed fins and nose cones, anything, that are designed to be mated with, say, 4oz rocket motors?

 

I read the thread about the guy who made his own motors for Estes rockets.  Has anyone made their own motors then mated them with their own rockets?

 

It sounds involved and complicated, wondering where I might start if I wanted to try that.  Realistically, though, stick rockets may be all I can handle.  Making the motor and attaching to the stick is straightforward.  Making a rocket with tube, fins, nose, etc, would likely be much more involved, but I wonder if anyone has "plans" on how to make a functioning model with perhaps a 1/2" ID homemade motor.

 

Thanks!

 

Not to much here since we really are all about pyrotechnics, not model rocketry. It's really not hard to make a model rocket and keep it lite, you just have to keep materials in mind. 

 

Rocket tubes made from a T8 or T12 tube protectors are about as light as it gets. Braces are super easy, nose cones are cheap enough to buy them, fins are stupid easy to make and mount, Google that.

 

Go with a 5/8" motor, our 1/2" motors are about an A in size. I make a crap-ton of 5/8" motors to fly girandolas, model rockets and missiles!! I like about 11 seconds of push on and endburner, the side wall is just starting to fail. 


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#5 Arthur

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Posted 26 October 2022 - 02:39 AM

Whether it's fireworks or amateur rocketry it's still a cardboard tube pushed skywards by a generic BP mixture



#6 SharkWhisperer

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Posted 27 October 2022 - 07:00 PM

Lots of good discussion on stick rockets, balancing or not, two sticks, etc.  Really good info and I appreciate it!

 

Are there any public domain models, either cardboard, maybe 3D printed fins and nose cones, anything, that are designed to be mated with, say, 4oz rocket motors?

 

I read the thread about the guy who made his own motors for Estes rockets.  Has anyone made their own motors then mated them with their own rockets?

 

It sounds involved and complicated, wondering where I might start if I wanted to try that.  Realistically, though, stick rockets may be all I can handle.  Making the motor and attaching to the stick is straightforward.  Making a rocket with tube, fins, nose, etc, would likely be much more involved, but I wonder if anyone has "plans" on how to make a functioning model with perhaps a 1/2" ID homemade motor.

 

Thanks!

There's only a couple of us that make our own BP motors for finned rocketry. Check out some older posts by member "HCB" and me on the topic. In short, I've made piles of 1-pounder endburners that match Estes F/G motor impulses. HCB hasn't been around in awhile but he has some videos posted of his 8-ouncers that lifted an Estes Patriot missile higher than the typical C motor could, with ejection and undamaged recovery. It's very doable. His first real attempt is here: . His channel name is Grass Roots. There's a lot of exchanges in the APC archives from start-to-finish that should be sufficient to answer most common questions. Ned also has an article at skylighter where he tried to reproduce D-impulse motors for use in finned rockets. https://www.skylight...ed00ba666&_ss=r . He used Estes Eliminator kits for testing--I've used these and they go together quickly with plastic fin cans. His post is pretty detailed. His motors worked but were a little anemic compared to HCB's and what I'm used to.

 

So long as your motor fits in your body tube it's a simple thing to fashion an appropriate engine mount for that rig and get CP/CG balanced right. In repeated flights, the key is having uniform OD motors, though if they're off by just a little you can sand them down or wrap a piece of masking tip around them to get them fitting.

 

Estes motors were already expensive before they went up by 30-40% again in 2021. Even with the cost of commercial rocket tubes (I've used Phil's and Woody's stock), it's pretty cheap to hand ram or press E/F-equivalent motors. A 2-pack of F-motors is now stanking $30 direct from Estes. Plus hazmat shipping costs. Though you can find them cheaper elsewhere. But at $15+/motor it's both cheaper and fun to make your own. For C-impulse and smaller, the effort/reward balance is a little less.

 

If you can make a short-cored semi-endburner that reliably flies on a stick and lifts a reasonable load without catoing then you can add a delay and ejection charge for parachute recovery. Or add "terminal" effects for a 1-way trip. Commercial rocket kits are not inexpensive and take a lot longer to build than taping a motor to a stick, but after building a few kits it's just a little extra "rocket science" to make your own any size and shape you like (I like big fat ones that don't disappear easily). Plenty of places for parts that are cheaper than kits--Balsa Machining Service (balsamachining.com) in NV is one of the good ones for body tubes, nosecones, finstock, engine mount pieces...

 

One caution is that finned rocketry can get as habit-forming and expensive as fireworking chems, paper products, and tooling. I've got well over 100 pounds of BP and APCP commercial motors that need firing and probably 40 unbuilt kits, not to mention boxes of build parts and parachute nylon that I accumulated during the pandemic. But tricking out rockets with smoke and crackle and star dumps during chute ejection and still coming back to do it again is a hoot!

 

Be forewarned to avoid the stinkeye from much of the model rocket community. Many if not most are older dudes who love rules and view fireworkers as reckless cowboys. And fireworkers often view the model rocket crowd as old "get-offa-my-lawn" farts with sticks up their asses. Meh, mixing it up is fun!


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#7 nordicwolf

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Posted 27 October 2022 - 10:22 PM

@Dagabu, how long are your 5/8" motors used in your rockets? 

@SharkWhisperer, how long are your 3/4" motors used in your rockets?

 

I presume I would need the following:

- end burner tooling of appropriate length for an appropriate tube

- tube support for the proper OD of tube

- BP, and this is another question.  Should the BP be ball-milled 75:15:10 or something else?  I have ERC charcoal.

 

I read elsewhere on this forum that nozzled motors should not use ball-milled BP but rather ~40mesh screen-mixed BP made from individually ball-milled comps.  Given endburner is nozzled, maybe it should be made that way?   (same post recommended ball-milled BP for nozzle-less motors but I digress.)

 

I have also read that nozzled motors should maybe be 60:30:10, with the 30 = 15 airfloat + 15 80mesh charcoal.

 

Thanks all!



#8 SharkWhisperer

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Posted 28 October 2022 - 02:55 PM

@Dagabu, how long are your 5/8" motors used in your rockets? 

@SharkWhisperer, how long are your 3/4" motors used in your rockets?

 

I presume I would need the following:

- end burner tooling of appropriate length for an appropriate tube

- tube support for the proper OD of tube

- BP, and this is another question.  Should the BP be ball-milled 75:15:10 or something else?  I have ERC charcoal.

 

I read elsewhere on this forum that nozzled motors should not use ball-milled BP but rather ~40mesh screen-mixed BP made from individually ball-milled comps.  Given endburner is nozzled, maybe it should be made that way?   (same post recommended ball-milled BP for nozzle-less motors but I digress.)

 

I have also read that nozzled motors should maybe be 60:30:10, with the 30 = 15 airfloat + 15 80mesh charcoal.

 

Thanks all!

NW, "standard" 1-pound tubes are 7.5" long with 3/4" ID. You can go longer or shorter depending on your needs, so long as your spindle will accommodate it. Not really an issue with short-core spindles, though swap/end marks on your rammers will be off with shorter tubes and may not fit longer tubes. Standard 7.5" is a great starting point. Tubes/BP is heavy and rockets need to stay reasonably light. Usually I go with standard, though I've cut some down for smaller rockets to save weight. Many modern motor mount designs do not have a thrust ring that restricts motor length, so you can usually vary it as long as you don't exceed CP/CG limits of that rocket.

 

BP for end-burners is usually about as hot as you can make it. I typically have about a 3/4" core past the nozzle, so it's a semi-endburner for initial oomph with cato potential, so my oxidizer content in propellant was often lower than 75%, but not as low as in true long-core core-burners. Exact comp and manufacture is personal preference. I usually use willow BP though likely moving over to ERC when stocks run low, ball-milled til it's about as hot as i can make it. granulated but not pucked/corned. Some use screen-mixed BP to good effect in motors, but I've never tried it and stick with ball milling.

 

Once dialed in, it's important to make BP batches large enough and close enough to the desired product so you get reproducible results. Get a few motors flying on their own, then add loads, and finally fly them in your rockets when you're satisfied. Even a basic rocket is going to be a bit of work and materials, so you don't want to risk blowing that up--get some reproducible results with a stick taped/glued on first and when you have confidence move on to the real deal. I hand-ram and am able in 1-pounders to get decently reproducible results. A press will give you more density (and total fuel/impulse) but is not necessary for consistency for me. Personal preference. Anything larger-diameter than 3/4" and i'd be using a press, for sure, to assure getting acceptable grain density. I don't use a tube support for hand-rammed BP 1-pounders but you may choose to.

 

Adding 80-mesh charcoal to BP is for sparky tails--effect not performance. Addition will absolutely affect propulsion kinetics, so decide before you begin if that is important to you. Probably easiest to keep it simple til your motors reliably fly the way you want. It's the same thing as flying any rocket except these hybrids come home to fly again (if desired). The motors are a fraction the cost of commercial motors (time not included) and are endlessly customizable. But they require testing. And the rockets are kinda expensive compared to a tube and stick, so you want to minimize the likelihood of them blowing up at launch. That said, even brand new Estes BP motors explode from time-to-time (see MESS reports at: https://www.motorcato.org/ if interested).



#9 SharkWhisperer

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Posted 29 October 2022 - 04:02 PM

Look out Apogee Rockets www ( apogeerockets.com)  and YT (Apogee Components) 

 

Most things you could want are there. Most firework rockets are height restricted by the motor and the mass. Unloaded an amateur rocket may well intrude on aviation airspace, and once it's risen to 1000+ feet it's going to land somewhere else.

At least in the US, federal law only really impacts larger rockets, and waivers are typically pretty easy to obtain. Class 1 hobby rockets are those with <125g propellant (4.4 oz), no substantial metal parts, total weight <1.5kg, and those don't need FAA/ATC notice/authorization so long as they're launched in a way not to be inordinately dangerous to people/property/aircraft. That said, state/local laws vary widely--good luck launching rockets anywhere in California (legally) without "permission".

 

Seems that most European countries have much stricter regulations regarding altitude limits etc than the US, but population density might play a role.

 

And yeah, high flights tend to disappear into the next county/state/province. Some nerds aim for height records, but I like big fat low & slow rockets that you can watch through the whole flight & don't require a hike to retrieve. For high flights, it can be useful to add a "sound device" that is released with the parachute to assist target reacquisition.

 

Now...back to fireworking


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#10 dagabu

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Posted 31 October 2022 - 08:35 PM

@Dagabu, how long are your 5/8" motors used in your rockets? 

@SharkWhisperer, how long are your 3/4" motors used in your rockets?

 

I presume I would need the following:

- end burner tooling of appropriate length for an appropriate tube

- tube support for the proper OD of tube

- BP, and this is another question.  Should the BP be ball-milled 75:15:10 or something else?  I have ERC charcoal.

 

I read elsewhere on this forum that nozzled motors should not use ball-milled BP but rather ~40mesh screen-mixed BP made from individually ball-milled comps.  Given endburner is nozzled, maybe it should be made that way?   (same post recommended ball-milled BP for nozzle-less motors but I digress.)

 

I have also read that nozzled motors should maybe be 60:30:10, with the 30 = 15 airfloat + 15 80mesh charcoal.

 

Thanks all!

 

My tubes are 4.5" long and I am only filling them to 3.5" with comp. 

 

Kinda; tooling can be longer such as the rammers but the same spindle is used no matter how long the rocket is on end-burners. 

 

I make ALL of my BP from hardwood charcoal and ballmill the 75:15:10 mix for 4 hours using Zirconium media in a #15 tumbler. 

 

As SW says, hot fuels work very well in endburners, whistle fuels are often used as well to increase impulse. I use BP due to consistency, hardwood (White Oak), Hafia KNO3 and rubber makers Sulfur make the commercial equivalent of Swiss BP 


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#11 nordicwolf

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Posted 04 November 2022 - 11:07 AM

Thanks all for the info.  It is greatly appreciated.

 

So yesterday I found a park with a sign explicitly ALLOWING the safe flying of model rockets.  Now I am wondering how I can work things so that I can use that park as a place to test my motors using sticks rather than models.

 

For models I know I need end-burners.  I have 1/2" tooling for that, but my 3/4" tooling is hybrid and cohete tooling. I would like to test a variety of motors at this park (4 oz end burners, 4 oz core burners, 1# hybrid and cohete.)

 

What would you say if someone asked what I was doing launching motors on sticks?  I suppose I could bring the Estes gear I have from my kids and even from my childhood as proof that I am into rocketry rather than that other hobby.  There just is no other easy place to launch without having to be even more sneaky about it.  I intend to try my motors in actual model rockets, but first I want to get consistent with making the motors.  Thanks.



#12 Arthur

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Posted 04 November 2022 - 12:54 PM

There is enough data on the web to find the sizes of Estes motors, likely the composition is stated in many places too. If you want to do amateur rocketry EVERYTHING rotates about Estes sizes. Kits are always made to fit Estes motors until the borders of High Power rocketry. 

 

Woody's is or was the dealer/distributor of a well designed thrust measuring system for rocket motors that gave thrust/time graphs for most possible amateur rocket sizes. 



#13 Richtee

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Posted 04 November 2022 - 04:19 PM

I just “reloaded” a couple Estes motors. I expect good performance. Those things are BUILT.


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#14 cmjlab

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Posted 05 November 2022 - 07:04 AM

Thanks all for the info.  It is greatly appreciated.
 
So yesterday I found a park with a sign explicitly ALLOWING the safe flying of model rockets.  Now I am wondering how I can work things so that I can use that park as a place to test my motors using sticks rather than models.
 
For models I know I need end-burners.  I have 1/2" tooling for that, but my 3/4" tooling is hybrid and cohete tooling. I would like to test a variety of motors at this park (4 oz end burners, 4 oz core burners, 1# hybrid and cohete.)
 
What would you say if someone asked what I was doing launching motors on sticks?  I suppose I could bring the Estes gear I have from my kids and even from my childhood as proof that I am into rocketry rather than that other hobby.  There just is no other easy place to launch without having to be even more sneaky about it.  I intend to try my motors in actual model rockets, but first I want to get consistent with making the motors.  Thanks.


I think, as you alluded to in your last paragraph, that you will just have to accept that someone will probably take issue and be prepared to apologize, explain, and possibly be willing to leave if the right person makes an issue out of it. Otherwise, until told by the property owner, I'd assume if you believe you are testing model rockets - then that is what you are doing (again, until someone with authority to do so, says otherwise). Good luck!

Charles

#15 dagabu

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Posted 06 November 2022 - 04:59 PM

Thanks all for the info.  It is greatly appreciated.

 

So yesterday I found a park with a sign explicitly ALLOWING the safe flying of model rockets.  Now I am wondering how I can work things so that I can use that park as a place to test my motors using sticks rather than models.

 

For models I know I need end-burners.  I have 1/2" tooling for that, but my 3/4" tooling is hybrid and cohete tooling. I would like to test a variety of motors at this park (4 oz end burners, 4 oz core burners, 1# hybrid and cohete.)

 

What would you say if someone asked what I was doing launching motors on sticks?  I suppose I could bring the Estes gear I have from my kids and even from my childhood as proof that I am into rocketry rather than that other hobby.  There just is no other easy place to launch without having to be even more sneaky about it.  I intend to try my motors in actual model rockets, but first I want to get consistent with making the motors.  Thanks.

 

Legally from both a federal and state (all 50 states must follow the Orange Book), you cannot use parks for your testing. Here where I live, the state allows testing on your property, the Orange Book allows explosive use same day on your own property but never on public property. 

 

Also, a rocket is like a bullet, you own it from cradle to grave, you may be in violation of DOT laws and rules in transporting explosives then in using a 'dangerous' item in close proximity to others, 'endangering' them. 

 

The city park will assume some responsibility for a model rocket and the federal laws also allow for model rockets and engines. Your best bet is to just make a chipboard model rocket with chipboard fins, glue a section of straw to the side and use MG igniters to light them.

 

Keep in mind that a ribbon or parachute HAS to be ejectable upon the end of the motor delay. NO descriptions of either are provided in any state or federal law that I know. 

 

You can use core burners for model rockets, you may shred them, they may fly poorly but there is no law that I have ever seen that dictates core type. ESTES is named so the assumption is an end burner but only impulse is specified as well as total black powder weight. 


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