Making rms cases?

[Dan Bryant]

Is it possible to make an aerotech rms case, and if so, what material do I need to use?

 

[heada]

It is physically possible but Aerotech owns the design and so you would need to obtain a license from them to produce your own. Intellectual Property laws and all that.

 

[Dan Bryant]

It is physically possible but Aerotech owns the design and so you would need to obtain a license from them to produce your own. Intellectual Property laws and all that.

I might be wrong, but if I understand correctly, in the uk you can use an ip without permission, as long as you don't make any money off of it?

 

[SolarYellow]

With some experience in making things, the only reason I can see to make one's own RMS hardware is to mess around with the mechanical aspects of the stuff from AT, such as a plugged/threaded/floating 29 FC that AT doesn't make, for example. Or carving completely unstressed mass off the closures, including excess length and perhaps shaving the thrust ring OD to match the OD of your airframe. Any permanent modification (i.e., removal or addition of metal) to the case will cause the motor to be "experimental/uncertified" and one must be very careful about legality of that wherever one happens to live.

In general, when I see a question like the OP, the fact that the answers are not obvious to the person asking the questions indicates that that person likely isn't qualified to get the job done with their current skill set.

 

[Dan Bryant]

With some experience in making things, the only reason I can see to make one's own RMS hardware is to mess around with the mechanical aspects of the stuff from AT, such as a plugged/threaded/floating 29 FC that AT doesn't make, for example. Or carving completely unstressed mass off the closures. Any permanent modification (i.e., removal or addition of metal) to the case will cause the motor to be "experimental/uncertified" and one must be very careful about legality of that wherever one happens to live.

In general, when I see a question like the OP, the fact that the answers are not obvious to the person asking the questions indicates that that person likely isn't qualified to get the job done with their current

With some experience in making things, the only reason I can see to make one's own RMS hardware is to mess around with the mechanical aspects of the stuff from AT, such as a plugged/threaded/floating 29 FC that AT doesn't make, for example. Or carving completely unstressed mass off the closures. Any permanent modification (i.e., removal or addition of metal) to the case will cause the motor to be "experimental/uncertified" and one must be very careful about legality of that wherever one happens to live.

In general, when I see a question like the OP, the fact that the answers are not obvious to the person asking the questions indicates that that person likely isn't qualified to get the job done with their current skill set.

I see.
I was just asking for future reference (as in a few years) since I was worried about how much the casings cost.

 

[SolarYellow]

OK. So the answer is, yes, you can make them. If you have the tools and skills to make them yourself, that's obvious. You'd still probably be better off doing whatever it is you do for money and buying the AT parts. So if you make parts, it's because you're having fun.

If you are going to have to pay someone else to make them, you'll likely pay at least several times whatever your cost would be to just buy them.

 

[Dan Bryant]

OK. So the answer is, yes, you can make them. If you have the tools and skills to make them yourself, that's obvious. You'd still probably be better off doing whatever it is you do for money and buying the AT parts. So if you make parts, it's because you're having fun.

If you are going to have to pay someone else to make them, you'll likely pay at least several times whatever your cost would be to just buy them.

That makes sense. Thanks.

 

[MidOH]

It's just an AL tube.

Make the forward piece with a shock cord eyelet, and a positive lock, keeping it threaded on, and no worries about patent BS.

You've made a whole new unique product.

Patents are largely useless aside from brand names. Only constant innovation keeps a company sharp. The company's that don't get this, go out of biz once they're legally copied.

 

[Rocketjunkie]

There is no problem cloning RMS cases for your own use. You open a whole new can of worms if you start selling them.
I ran a batch of 38/720 cases and closures in the late 1990s and I'm glad I did. I put 7 Rx I85s (580 N-s, 7 sec. burn) in my Ultimate Max and it shreded about 4 sec into the burn. Without a chute it landed butt end down on the road destroying all 7 cases.
Static test of I85. Note the un-anodized case, one of the clones.

 

[jsdemar]

I’ve designed a bolted case compatible with RMS grains and nozzles. Flew it with 4gr BT and RL loads.

 

[SolarYellow]

NM....

 

[CoyoteNumber2]

Static test of I85. Note the un-anodized case, one of the clones.

I'll order a dozen!

 

[thequick]

The cases look pretty tough to make to me. Boring something that long, thin walls that won’t have much strength to support the cutting tools. The tolerances seem pretty tight too. Just my 2c

 

[OzHybrid]

That makes sense. Thanks.

I believe it's illegal to manufacture your own propellant in the UK without some serious licences you'd need to obtain. So not doable in practical terms.
If you're making a case for an official RMS reload, the motor would be an experimental motor. Not sure what the UK rules are there.
Hybrids are doable. That's where I'd go if I was in the UK. IN THE UK. Heads up for future answers....

 

[StuartL_UK]

The UK Aerotech vendor do rent cases too, if that's an option.

 

[Frederocket]

It is physically possible but Aerotech owns the design and so you would need to obtain a license from them to produce your own. Intellectual Property laws and all that.

That is not a true statement. As an individual, I or anyone can clone anything anyone has the skill to make, as long as I or the individual do not offer it for sale. Also patents are not forever.

 

[Tim51]

Is it possible to make an aerotech rms case, and if so, what material do I need to use?

Certainly possible, but strongly advise you seek professional UK legal advice first. Even if you're using commercially produced APCP reloads, from what I understand from your post, you're intending to put them in a casing that the manufacturer has not tested or authorised, so the completed motor would be 'EX' (= 'home made") which is illegal here in the UK.

 

[Rocketjunkie]

I'll order a dozen!

Sorry, I don't have access to the CNC lathe I used to make them. They are direct clones of the Aerotech hardware. Find a nearby maker club and see if you can use their equipment. The tube is 1-1/2 OD, .058 (17 gauge) wall.

 

[Dave P]

You would be better off making motors with radial seals instead of axial seals and snap rings. Easier to make and seals better, like Dr K taught us!

 

[CoyoteNumber2]

Sorry, I don't have access to the CNC lathe I used to make them. They are direct clones of the Aerotech hardware. Find a nearby maker club and see if you can use their equipment. The tube is 1-1/2 OD, .058 (17 gauge) wall.

I meant the I85, looks like a fun motor!

 

[Rocketjunkie]

I meant the I85, looks like a fun motor!

It is. Here's the thrust curve. And a video of one in a saucer.

 

[Rocketjunkie]

The cases look pretty tough to make to me. Boring something that long, thin walls that won’t have much strength to support the cutting tools. The tolerances seem pretty tight too. Just my 2c

You buy tubing. If there is none, get the correct ID and turn the OD to size. An example is 54mm (2.125" OD, .058 wall) is not a standard size. Either get a mill run (IIRC min 1000') or turn down some 2.25" OD tube.

 

[kramer714]

so... If I make a case, fit-form-function, identical to an Aerotech case, SAME materials tolerances etc. If I use a NAR/Tripoli certified reload, and a 'non aerotech case' is the motor considered certified, if i were to present it to a RSO at a non EX launch?

Looking for an answer from NAR/Tripoli motor testing members.

Just a hypothetical, I'm not suggesting you build your own motor cases, plus be respectful of other folks IP

 

[jsdemar]

so... If I make a case, fit-form-function, identical to an Aerotech case, SAME materials tolerances etc. If I use a NAR/Tripoli certified reload, and a 'non aerotech case' is the motor considered certified, if i were to present it to a RSO at a non EX launch?

Looking for an answer from NAR/Tripoli motor testing members.

Just a hypothetical, I'm not suggesting you build your own motor cases, plus be respectful of other folks IP

No, the hardware would have to licensed from the original manufacturer, or cert tested as a new combination of cross-compatible hardware and reload. There are more nuances to this, and they all aren't written rules.

 

[CoyoteNumber2]

so... If I make a case, fit-form-function, identical to an Aerotech case, SAME materials tolerances etc. If I use a NAR/Tripoli certified reload, and a 'non aerotech case' is the motor considered certified, if i were to present it to a RSO at a non EX launch?

Depends on who the RSO is.

 

[jsdemar]

At a Tripoli launch, it's a Research motor and allowed.
At a NAR launch, it's an uncertified motor and not allowed.
If you sneak it through a NAR check in and something bad happens, insurance won't cover it.

 

[WizardOfBoz]

The other thing about this is that an Aerotech casing costs, what?, about $100 or €100? More or less? If you spend about 80 on the proper material (6061 or 7075 aluminum I think) and then use about 30-40,000 in a precision lathe, and several hundred on testing equipment, you'll end up with an end product that is less aesthetically pleasing, weaker, less durable, and is more likely to fail. So there's that....

No offense, but if you have to ask what material to use and how hard it would be to make, you have several years of experience to gain, and lots of expensive tools to aquire before you can do this.

If you were a journeyman machinist with a shop set up, you'd still have to be concerned about getting the end product properly heat treated and anodized.

Makes that Aerotech product seem like a bargain, right?

Common Aerospace Alloys (this assumes that you will use a non-ferrous metal, per most of the safety rules). So some aluminums:

• 6061: A high-quality material with a great strength-to-weight ratio, making it a popular choice for aircraft and spacecraft. It's also known for its weldability and versatility.
• 6063: Similar to 6061, but with better workability and higher corrosion resistance.
• 7020: Can provide extra strength, especially for safety aspects.
• 7075: A high-strength material with good corrosion resistance and a high strength-to-weight ratio. It's often used in applications where weight is critical, like aircraft and spacecraft.
• 2014: A good choice for frameworks due to its strength and machinability, but it doesn't have the same level of corrosion resistance as other grades.
• 2024: A heat-treatable alloy with copper as the main alloying element. It's commonly used in aircraft structures because of its high strength and fatigue resistance.
• 3003: Known for its great strength and workability.

 

[heada]

That is not a true statement. As an individual, I or anyone can clone anything anyone has the skill to make, as long as I or the individual do not offer it for sale. Also patents are not forever.

35 U.S.C. § 271 says otherwise. Even violating a patent for private use is illegal.

AT wouldn't do anything about it unless you offer them for sale and yes, patents do expire but 20 years is still a long time.

 

[Rocketjunkie]

The other thing about this is that an Aerotech casing costs, what?, about $100 or €100? More or less? If you spend about 80 on the proper material (6061 or 7075 aluminum I think) and then use about 30-40,000 in a precision lathe, and several hundred on testing equipment, you'll end up with an end product that is less aesthetically pleasing, weaker, less durable, and is more likely to fail. So there's that....

No offense, but if you have to ask what material to use and how hard it would be to make, you have several years of experience to gain, and lots of expensive tools to aquire before you can do this.

If you were a journeyman machinist with a shop set up, you'd still have to be concerned about getting the end product properly heat treated and anodized.

Makes that Aerotech product seem like a bargain, right?

Common Aerospace Alloys (this assumes that you will use a non-ferrous metal, per most of the safety rules). So some aluminums:

• 6061: A high-quality material with a great strength-to-weight ratio, making it a popular choice for aircraft and spacecraft. It's also known for its weldability and versatility.
• 6063: Similar to 6061, but with better workability and higher corrosion resistance.
• 7020: Can provide extra strength, especially for safety aspects.
• 7075: A high-strength material with good corrosion resistance and a high strength-to-weight ratio. It's often used in applications where weight is critical, like aircraft and spacecraft.
• 2014: A good choice for frameworks due to its strength and machinability, but it doesn't have the same level of corrosion resistance as other grades.
• 2024: A heat-treatable alloy with copper as the main alloying element. It's commonly used in aircraft structures because of its high strength and fatigue resistance.
• 3003: Known for its great strength and workability.

Aerotech uses and the most common alloy is 6061-T6 seamless drawn over mandrel. You can get small amounts from places like Onlinemetals.com 29 mm (1.125", .058" wall) and 38 mm (1-1/2", .058" wall) are standard sizes. Haven't checked 75 and 98 mm. Less aesthetically pleasing yes but otherwise just as good as the licensed ones. My cloned 38/720 cases have been going for 25 years with no issues. If they do wear out, you can make more.

 

[WizardOfBoz]

Aerotech uses and the most common alloy is 6061-T6 seamless drawn over mandrel. You can get small amounts from places like Onlinemetals.com 29 mm (1.125", .058" wall) and 38 mm (1-1/2", .058" wall) are standard sizes. Haven't checked 75 and 98 mm. Less aesthetically pleasing yes but otherwise just as good as the licensed ones. My cloned 38/720 cases have been going for 25 years with no issues. If they do wear out, you can make more.

Rocketjunkie,
Yes, DOM 6061-T6 seems to be a good choice. And it sounds like you know what you're doing. Did you single-point the threads on a lathe? Do you have a machine shop? Machining experience?
My point was not that someone with expertise and good shop judgement (as I suspect you have) cannot make a casing. But rather, the OP in asking "Is it possible to make an Aerotech case?" seemed to indicate that production decisions (like alloy, which machine tools, etc) were not familiar to him. Pressure inside these engines is cited as "700-3500 psi" which implies failure modes that anyone making one of these should be aware of. So my point was "Yes, you can do it, but to do it properly you really need to learn a lot of skills and be aware of safety implications. And unless you already have a lathe or a friend with one (and in fact, even if you do), making a case will likely be more expensive than buying one".
I grew up working in my Dad's machine shop on and off. I'm an engineer by training but I never forgot just how good a competent Tool and Diemaker, or a journeman machinist really is. In fact, if I had the time and money I'd put my Monarch 10EE into better shape and make casings myself. As it is, I'm going to have to sell the thing.