http://www.mach1rocketry.com/store/p212/BT50%2F24mm_Motor_Tube_Filament_Wound_Fiberglass_Airframe_48%22_Or_By_the_Foot.html
comes out to about a dollar a foot, cheaper than 1in Garolite or carbon
sleeve.
On Friday, February 12, 2021, Dr Edward Jones <RocketPioneer@xxxxxxxxx>
wrote:
Starting with the "62.5-gram Rule" [* below], I'm developing a
nozzle-less core burner with that nominal grain weight. Formulations
are well-characterized. "No metal components" is also part of the
paradigm. While experiments continue, I'm using a 0.7-inch OD grain of
7.0-inches L, with the web equal to the core diameter, about
0.25-inch.
One other intent is to minimize motor dry weight, and every milligram
matters. Thus I aim for highest possible maximum mass fraction in a
non-metal case of about 7" L x 0.7" ID.
Chamber pressure peaks at about 100-psia, midway in the burn. At
burnout, Pc is somewhat less, yet not trivial.
I'm starting with strong, thin cotton paper, rolled with minimal
adhesive. I'm considering impregnating the paper with boric acid
and/or sodium silicate, to minimize burn-thru at burnout. Likewise,
Tyvek may proved a better choice, impregnated or otherwise.
Since composite fiber tubing is quite pricey, anyone have ideas for
other ways to make this ultra-light motor case work?
Thanks in advance.
Edward
* On 08/11/2006: The Department of Justice is amending the regulations
of the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) to
clarify that the requirements of part 555 do not apply to model rocket
motors consisting of ammonium perchlorate composite propellant, black
powder, or other similar low explosives, containing no more than 62.5
grams of total propellant weight, and designed as single-use motors or
as reload kits capable of reloading no more than 62.5 grams of
propellant into a reusable motor casing. This final rule is intended
to provide rocketry hobbyists with guidance to enable them to enjoy
their hobby in compliance with the safety and security requirements of
the law and regulations.