This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.
'Model', 'high power', 'advanced', and 'amateur' are all terms which have
many definitions, depending to whom you are speaking. In r.m.r., and in the
FAQ documents, the definitions (if any) accepted by the NFPA, National
Association of Rocketry, and Tripoli High Power Rocketry Association are
used. If these definitions conflict the NAR definition is used.
'Model rockets' are rockets that conform to the guidelines and restrictions
defined in the NFPA 1122 document. These rockets weigh less than 1500
grams, contain less than 125 grams of total fuel, have no motor with
more than 62.5 grams of fuel or more than 160 NS of total impulse, use
only pre-manufactured, solid propellant motors, and do not use metal
body tubes, nose cones or fins. One inconsistancy with this is the
CPSC definition of a model rocket motor, which by their definition must
contain no more than 80NS total impulse. NFPA document 1127-94 contains
the most complete definition of a model rocket and the model rocket safety
code. This is the same safety code as adopted by the NAR.
'Large Model Rockets' is a term used in the FAA FAR 101 regulations. It
refers to NAR/NFPA model rockets that are between 454 and 1500 grams
(1 to 3.3 pounds) total liftoff weight and contain more than 113 grams
but less than 125 grams of total fuel.
'High power rockets' are rockets that exceed the total weight, total
propellant or single motor total impulse restrictions of model rockets,
but otherwise conform to the same guidelines for construction materials
and pre-manufactured, commericially made rocket motors. High power rockets
also allow the use of metal structural components where such a material
is necessary to insure structural integrity of the rocket. High power
rockets have no total weight limits, but do have a single motor limit of
no more than O power (40,960NS maximum total impulse) and have a total
power limitation of 81,920NS total impulse. NFPA document 1127-1985 contains
the most complete definition of a high power rocket and also the high power
rocketry safety code. This safety code has been adopted by both the NAR
and TRA. Metal bodied rockets are allowed by NFPA 1127 where metal is
required to insure structural integrity of the rocket over all of its
'Amateur' rockets covers all other non-professional rockets that do not
meet the criteria for model or high power rockets. This includes metal
bodied rockets, liquid or hybrid fueled rockets, and rockets with any
type of homemade rocket motor.
'Experimental' rockets is an ambiguous term. In the early 1980's it
was used (reportedly coined by the magazine 'California Rocketry') to
describe rockets that exceeded the model rocket limit at that time (1
pound total liftoff weight and no motor above F power). More recently,
it has been used by the Tripoli Rocketry Association to describe the
class of rockets that use pre-manufactured solid or hybrid rocket
motors but that do not qualify as high power rockets. This includes
metal bodied rockets and those with more than 80,000NS of total
'HPR-lite' is not any type of 'official' rocket designation but has been
used to refer to rockets that exceed the old NFPA model rocket limit of
1 pound but still qualify as NFPA model rocket under current guidelines.
These rockets typically use E through G power and are built with much
the same techniques as high power rockets. This term originated in the
internet rec.models.rockets newsgroup. It should be noted that this
term refers to legal model rockets, not any type of high power rocket,
and might therefore be misleading to many. The term 'Large Model Rocket'
should be used instead.
Another term that has no formal definition but is more and more being
used in the literature is 'hobby rocketry'. This term includes both
model and high power rockets, but excludes amateur rockets. The
term 'consumer rocketry' has also been used, and means the same thing.
The term 'non-professional rocketry' encompasses all forms of model,
high power and amateur rocketry.
Finally, the editor of this document wishes to get on his soapbox for
just one moment and add the term 'stupid rocketry' to cover all those
who attempt to casually produce their own rocket fuel and/or motors
without the benefit of very serious study, and implementation, of the
processes involved and safety measures required. Especially note
that this comment is NOT aimed at serious amateur rocketry
organizations, college level research, etc. End of soapbox.