This article describes the role of various federal agencies relevant to the storage, shipment, and use of motors for sport rocketry. The storage, shipment, and use of motors for sport rocketry are regulated by a variety of Federal agencies, in addition to any state and local agencies you may have to deal with. Understanding the various regulations is important for two reasons: It helps ensure that you won’t accidentally violate a regulation (which in the worst case scenario could have serious consequences) and it may help you make a persuasive case for local authorities, who may wish to be more restrictive than the law requires.

The U.S. Consumer Product Safety Commission (CPSC)

The CPSC regulates the sale of toy propellant devices, which includes small rocket motors. They are responsible for age requirements for purchasers of larger motors.

The Department of Transportation

The DOT regulates the shipment of hazardous materials, including rocket motors of all types, in interstate commerce. The DOT works on an exemption basis: The way it works is that the shipment of all hazardous materials, including rocket motors, is forbidden, unless an exemption is granted by the DOT. A manufacturer wanting to ship a motor must therefore submit it to DOT, where it is evaluated and an exemption number, or EX number, is given. The EX number is issued in a letter which states how the material is classified, and the rules applicable to its shipment. Manufacturers may ask for additional relief, so that for example the DOT may approve the shipment of a substance normally classified as an explosive as if it were merely a flammable solid, provided specific quantity limits and packaging instructions are met. The typical sport rocketry enthusiast is not likely to run afoul of DOT regulations when driving around with motors in their car trunk, unless they are engaged in transporting experimental motors which have not been issued an EX number.

However, knowledge of the EX number system and the applicable DOT shipment regulations is necessary in order to properly ship motors using the Postal Service, UPS, or other carrier. Rocket motors must never be loaded onto a passenger carrying airliner, either in checked baggage or in carry on luggage. Many motors can be shipped using the Postal Service, provided that the package is properly marked and documented. If you have cause to send a motor back to a manufacturer, call and ask for instructions–many will send shipping materials to you that are designed to keep everyone compliant with the applicable regulations.

The Bureau of Alcohol, Tobacco, and Firearms

The BATF regulates the use of explosive materials, including storage. Further, if the material is acquired in interstate commerce, the users themselves must have an appropriate BATF permit. While the rules may enable you to launch rockets legally without this permit, if you are careful about what you launch and where you buy it, you must comply with BATF requirements for storage regardless.

The regulations ( in this area changed in December 2000, but unfortunately, (or perhaps fortunately) the rule change was botched and the new regulations are currently not being enforced with regard to rocket motors, pending another formal rule-making process. The primary reason for the confusion is that the system for classifying hazardous materials is changing worldwide, and the BATF didn’t get all the details right. But you may need to know the details, both because the new rules are likely to get it right next time, and because it is very possible that you will encounter the same issues in dealing with your local authorities. The BATF regulations can be found in the Code of Federal Regulations (CFR), Title 27, Part 55, which in shorthand is written 27 CFR 55. These regulations are officially used by BATF to interpret the public law (91-452) which requires them to regulate explosives.

The primary issue is, “What is covered by BATF regulations?” It used to be the case that a lot of rocket motors were not. Prior to 12/98, The BATF regulations, in. 27 CFR 55.141, which covers Exemptions, included in (a) (7)

“The importation and distribution of fireworks classified as Class C explosives and generally known as “common fireworks”, and other Class C explosives, as described by U.S. Department of Transportation regulations in 49 CFR 173.100 (p), (r), (t), (u) and (x).”

In the regulations referred to by 27 CFR 55.141 (a) (7), the DOT’s 49 CFR 173.100 (u) is about toy propellant devices, defined broadly enough to include rocket motors using both cardboard and composite casings.

The BATF in 27 CFR 55.11 had already defined “Common Fireworks” as:

“Any small firework device designed to produce visible effects by combustion and which must comply with the construction, chemical composition, and labeling regulations of the U.S. Consumer Product Safety Commission, as set forth in Title 16, Code of Federal Regulations, parts 1500 and 1507. Some small devices designed to produce audible effects are included, such as whistling devices, ground devices containing 50 mg or less of explosive materials, and aerial devices containing 130 mg or less of explosive materials. Common fireworks are classified as Class C explosives by the U.S. Department of Transportation (DOT). 49 CFR 173.100(r).”

So, before 12/22, if US CPSC regulated it, and/or DOT regulated it as a toy propellant device, it was exempted from regulation by BATF. However, DOT has been adopting a more refined classification of hazardous materials and is also adopting the United Nation’s standard for classifying hazardous materials, which used to regulate world-wide shipments. Whereas explosives used to be classified as Class A, Class B, or Class C, along with a bunch of wordy definitions such as the one for “Common Fireworks” above, they are now classified in much greater detail, using a system of UN numbers as well as a set of numeric classes and compatibility groups. The new numeric classes designate the kinds of bad things that can happen when things go wrong in shipment, and the UN numbers describe the material itself.

For example, small BP and composite motors both used to be simply called Class C explosives. BP motors are now classified as UN0432, Class 1.4S, whereas Small (<30g) composite single use became UN0349 1.4S. There are lots additional classifications for various sizes and types of motors. See Table 1 for a list of applicable UN numbers, and Tables 2 through 5 for how they apply to many of the current motor manufacturers.

When the system was first being used, there was a tendency to treat the new classifications just like the old ones. Aerotech has a letter from the DOT on their site, for example, issuing EX numbers for RMS kits and designating them UN0351 1.4C. And, “to facilitate translation to the UN system,” the DOT helpfully adds the translation “Toy Propellant Devices.” So, before 12/98, these RMS kits were classified by DOT in a way that exempted them from regulation by BATF (because of the reference by BATF to DOT’s 49 CFR 173.100 (u) and their own definition of Common Fireworks).

Then BATF changed the rules. First, they deleted the definition of Common Fireworks in the rules that became effective 12/98. Instead, they substituted “Consumer Fireworks” which sounded a lot like the earlier definition EXCEPT that it lists specific UN numbers–in this case UN0336 and UN0337–instead of the more general Class C explosives. Neither UN0336 and UN0337 are relevant to rocketry, and in fact are used for materials classified as 1.4G. This is important for some states that regulate materials by class instead of specific UN number–for example, you may have much more of a problem complying with local standards for 1.4G than you do for 1.4S, which is what Estes motors are. Materials classified as 1.4G may be banned as fireworks!

BATF also changed our key exemption clause, 27 CFR 55.141 (a) (7), to exempt only:

“The importation, distribution, and storage of fireworks classified as UN0336, UN0337, UN0431, or UN0432 explosives by the U.S. Department of Transportation at 49 CFR 172.101 and generally known as “consumer fireworks” or “articles pyrotechnic.”

UN0336 and UN0337 are for fireworks. UN0431 and UN0432 are “articles pyrotechnic.” UN0432 in particular is the designation given by the DOT to small black powder rocket motors, so Estes and Quest are still exempt.

However, none of the UN numbers used for composite propellant motors were included, even for those classified as 1.4S, just like Estes motors are. This is apparently not what the BATF intended.

As a result, a letter ( was issued on 1/5/99 to BATF Division Directors acknowledging the error and directing that, pending a new rule making process, no enforcement action be taken regarding the importation, distribution, and storage of a list of explosives including:

“Model rocket motors classified by the U.S. Department of Transportation at 49 CFR 172.101 as UN0349, UNO351, UN0471, NA0276, or NA0323; consisting of ammonium perchlorate composite propellant, black powder, or other similar low explosives; containing no more than 62.5 grams propellant weight; and designed as single use motors or as reload kits.”

Note that there has been some vagueness about the use of 62.5g of propellant criterion in the past. Aerotech complies with the law to the letter in shipping reload kits with multiple grains each less than 62.5g. The reason some of the grains in those kits are wrapped in additional layers of plastic is that from the DOT’s perspective, the larger package contains several reload “kits.” It appears that the BATF intends to regulate these reloads based on the motor they are designed to go into, not the size of the individual grains.

At present, we are back to the status quo as far as the BATF goes. However, you can bet that the NPRM will not be as vague as the DOT about the definition of a model rocket motor reload kit containing no more than 62.5 grams of propellant weight. It appears that BATF wants to exempt UN0432, UN0349, UN0471, for sure. It appears that they would like to regulate UN0186, UN0275, and those UN0351 reload kits that are intended to be assembled into a motor with more than 62.5 grams of propellant weight, regardless of the weight or packaging of individual grains. Here they would be in some degree of conflict with DOT, which permits UN0351 to be shipped around in 20 pound boxes as if it were flammable solid. There is also talk of permitting some sort of Sport Rocketry permit, with a break on the cost and maybe even a break on the storage requirements. Time will tell.

Table 1. UN Codes applicable to sport rocketry.

Code Description What is covered
UN0432 Articles, pyrotechnic Small black powder motors.
UN0349 Articles, explosive, n.o.s. Ammonium Perchlorate (AP) Single use (SU) <30g total propellant
UN0471 Articles, explosive, n.o.s. AP SU >30g but <62.5g total propellant
UN0186 Rocket motors AP SU >62.5g total propellant
UN0351 Articles, explosive, n.o.s. AP reloads <62.5g per propellant grain
UN0275 Cartridges, power device AP reloads >62.5g per propellant grain

Table 2: Black powder motors

Manufacturer Motor Types UN# DOT EX# Class
Estes 1/4A to D UN0432 EX-9806052 to 53
EX-9001146 to 66
EX-8007022 to 25
Quest Micromax UN0432 EX-9810082 1.45
Quest A to C UN0432 ? 1.45

May ship up to 20 pounds per 4G box as UN1325 4.1 Flammable Solids per DOT E-7887
Exempted from regulation by BATF per 27 CFR 55.141 (a) (7)

Table 3: Small Composite motors

Manufacturer Motor Types UN# DOT EX# Class
Aerotech SU D to E
<30 g propellant
EX8205051 1.4S
Apogee SU D to E
<30 g propellant
? 1.4S

May ship up to 20 pounds per 4G box as UN1325 4.1 Flammable Solids per DOT E-7887
These motors are technically affected by BATF regulation; however, enforcement is on hold pending another rule making cycle

Table 4: Large Composite motors and reload kits

Manufacturer Motor Types UN# DOT EX# Class Comments
North Coast F62
>30, <62.5 grams of propellant total
EX-9610090 1.4C See Notes.
Aerotech SU F to G
>30 g, <62.5 g propellant total
EX8205051 1.4C See Notes.
Aerotech RMS D to J <62.5 g propellant per grain UN0351 EX9305148 1.4C White Lightning reloads and J260HW, J390HW EFX™ and Turbo™ hybrid reload kits)
Aerotech RMS D to J <62.5 g propellant per grain UN0351 EX9305149 1.4C Blue Thunder reloads and J145H, J170H and J210H hybrid reload kits)
Aerotech RMS D to J <62.5 g propellant per grain UN0351 EX9305150 1.4C Black Jack reloads.

Note 1: May ship up to 20 pounds per 4G box as UN1325 4.1 Flammable Solids per DOT E-7887.
Note 2: All of these motors are technically affected by BATF regulation; however, enforcement is on hold pending another rule making cycle.

Table 5: Regulated motors and reload kits

Manufacturer Motor Types UN# DOT EX# Class Comments
Aerotech SU >G >62.5 g propellant total UN0186 EX8604200 1.3C May ship up to 12 pounds per 4G box as UN0351 1.4C Articles Explosive n.o.s. per DOT E-10996
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9404152 1.3C J90W, J275W, J415W, K550W, K458W, L952W, M1419W, M1939W, K700W M845HW, N2000W reload kits
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9404153 1.3C J180T, J460T, J800T, K1100T reload kits
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9404154 1.3C I112J, I154J reload kits with large propellant grains (no longer made this way)
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9502046 1.3C J135W reload kit
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9502047 1.3C K185W reload kit
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9807120 1.3C 75mm White Lightning reload kits using 669 g propellant grains
Aerotech RMS >J >62.5 g propellant per grain UN0275 EX9807121 1.3C 98mm Blue Thunder reload kits using 1,176 g propellant grains

Appendix: Excerpts from the DOT’s Explosive Classification System

173.50(a) Explosive. For the purpose of this subchapter, an explosive means any substance or article, including a device, which is designed to function by explosion (i.e., an extremely rapid release of gas and heat) or which, by chemical reaction within itself, is able to function in a similar manner even if not designed to function by explosion, unless the substance or article is otherwise classed under the provision of this subchapter.

173.50(b) Explosives in Class 1 are divided into six divisions as follows:

Table A-1. Classification Codes

Description of substances or article to be classified Compatibility group Classification code
Primary explosive substance A 1.1A
Propellant explosive substance or other deflagrating explosive substance or article containing such explosive substance C 1.1C, 1.2C, 1.3C, 1.4C
Substance or article so packed or designed that any hazardous effects arising from accidental functioning are limited to the extent that they do not significantly hinder or prohibit fire fighting or other emergency response efforts in the immediate vicinity of the package S 1.4S

173.53 Provisions for using old classifications of explosives.

Where the classification system in effect prior to January 1, 1991, is referenced in State or local laws, ordinances or regulations not pertaining to the transportation of hazardous materials, the following table may be used to compare old and new hazard class names.

Current classification Class name prior to Jan. 1, 1991:
Division 1.1 Class A explosives.
Division 1.2 Class A or Class B explosives.
Division 1 3 Class B explosive.
Division 1.4 Class C explosives.

Submitted by: Ted Cochran