Model rocket

According to the United States National Association of Rocketry (NAR)'s Safety Code,[1] model rockets are constructed out of lightweight and non metallic parts.

Despite its inherent association with extremely flammable substances and objects with a pointed tip traveling at high speeds, model rocketry historically has proven[2][3] to be a very safe hobby and has been credited as a significant source of inspiration for children who have eventually become scientists and engineers.

But then Orville read articles written in Popular Mechanics by G. Harry Stine about the safety problems associated with young people trying to make their own rocket engines.

The machine, nicknamed "Mabel", made low-cost motors with great reliability, and did so in quantities much greater than Stine needed.

[8] In recent years, companies like Quest Aerospace[9] have taken a small portion of the market, but Estes continues to be the main source of rockets, motors, and launch equipment for the low- to medium-power rocketry hobby today.

Since the advent of high-power rocketry, which began in the mid-1980s with the availability of G- through J-class motors (each letter designation has up to twice the energy of the one before), a number of companies have shared the market for larger and more powerful rockets.

By the early 1990s, Aerotech Consumer Aerospace, LOC/Precision, and Public Missiles Limited[10] (PML) had taken up leadership positions, while a host of engine manufacturers provided ever larger motors, and at much higher costs.

Companies like Aerotech, Vulcan, and Kosdon were widely popular at launches during this time as high-power rockets routinely broke Mach 1 and reached heights over 3,000 m (9,800 ft).

In a span of about five years, the largest regularly made production motors available reached N, which had the equivalent power of over 1,000 D engines combined, and could lift rockets weighing 50 kg (110 lb) with ease.

Custom motor builders continue to operate on the periphery of the market today, often creating propellants that produce colored flame (red, blue, and green being common), black smoke and sparking combinations, as well as occasionally building enormous motors of P, Q, and even R class for special projects such as extreme-altitude attempts over 17,000 m (56,000 ft).

High-power motor reliability was a significant issue in the late 1980s and early 1990s, with catastrophic engine failures occurring relatively frequently (est.

Reloadable motor designs (metal sleeves with screwed-on end caps and filled with cast propellant slugs) were introduced by Aerotech and became very popular over the span of a few years.

While catastrophes at take-off (CATOs) still occur occasionally with reloadable motors (mostly due to poor assembly techniques by the user), the reliability of launches has risen significantly.

Depending on the weight of the rocket and the maximum speed threshold of the airframe and fins, appropriate motor choices can be used to maximize performance and the chance of successful recovery.

A primary motivation for the development of the hobby in the 1950s and 1960s was to enable young people to make flying rocket models without having to construct the dangerous motor units or directly handle explosive propellants.

If a large black-powder motor is the upper stage motor of a rocket that exceeds the maximum recommended takeoff weight, or is dropped or exposed to many heating/cooling cycles (e.g., in a closed vehicle exposed to high heat or a storage area with inconsistent temperature control), the propellant charge may develop hairline fractures.

Therefore, rocket motors with power ratings higher than D to F customarily use composite propellants made of ammonium perchlorate, aluminium powder, and a rubbery binder substance contained in a hard plastic case.

Secondly, assembly of larger composite engines is labor-intensive and difficult to automate; off-loading this task on the consumer results in a cost savings.

On top of the propellant is a tracking delay charge, which produces smoke but in essence no thrust, as the rocket slows down and arcs over.

Model rocket motors mostly don't offer any sort of thrust vectoring, instead just relying on fins at the base to keep the vehicle aerodynamically stable.

[17] For miniature black powder rocket motors (13 mm diameter), the maximum thrust is between 5 and 12 N, the total impulse is between .5 and 2.2 Ns, and the burn time is between .25 and 1 second.

[22] After this, there is a new string of characters such that the impulse in newton-seconds is first, followed by the motor classification, the average thrust in newtons, followed by a dash, and the delay time in seconds.

This is slightly different from tumble recovery, which relies on some system to destabilize the rocket to prevent it from entering a ballistic trajectory on its way back to Earth.

Typically, a ball or mass of fireproof paper or material, sometimes referred to as recovery wadding, is inserted into the body before the parachute or streamer.

A very small number of people have been pursuing propulsive landing to recover their model rockets using active control through thrust vectoring.

As parachute systems can be prone to failure or malfunction, model rocket cameras need to be protected from impact with the ground.

This system used a 1.5 inch round film negative held in a large pill-shaped camera body with the lens facing forwards.

Created by Mike Dorfler, the CINEROC[30] held 20 seconds of Super 8mm film that ran at 30 fps, making for a slow-motion effect.

A major reason for this was the advent of the 'Key-Fob camera' - many of which were more powerful, lighter and easier to attach to any rocket, and did not need a specific model to do so, and had expandable memory in the form of Mini SD cards, and were much less expensive.

These devices also have the advantage of rechargeable batteries, and since they were built on the same plug-and-play technology Flash Drives use, do not need any extra drivers installed into a computer for them to work.