Experimental Hybrid Rocket Motor
EX - Experimental Hybrid Rocket Motors
This is a new area of experimental
motors that I will venture into. For now I include a couple of links
that are particularly germain:
I recently picked up a
little beauty, an "Aerocon Integral Tank Hi-Performance Hybrid system H
Class" motor. It's by Bill Colburn and apparently he was planning on
getting them certified but never followed through. This was one of a
small lot of initial run of them. I will post more later, but for now
there are the two pages that come with the motor. Page
It'll make a great EX motor as the injector is not floating so it'll
take anything in the chamber without worry of compressive loads. Stock
it uses acrylic grains, but I hear it works great with paper, HTPB, PVC
and other materials.
I now have Bill Colburn's new book "A
for Hybrid Propulsion Design
" and am reviewing it. The CD
that comes with it also has a wealth of information.
For Simulations I am looking at the Rational
Technology Hybrid Design Program
, but may hold off as the CDROM
that comes with Bill Colburn's book has a hybrid design program that,
well, I've paid for already. I don't know how they compare. Steve
Daniels has started an open source HSIM package
; Todd Moor's HDAS
there are other design spreadsheets I need to link in here.
[old content warning: - I'm flying HyperTek, PP, and RATT motors in
hybrid form now; a lot of specific content is in my detail pages]
Right now my tact will be to essentially duplicate an existing motor
using as much stock componentry as possible. If I stay close to
existing design parameters I should not need, to such an extent, in
depth testing as with starting a new or ambitious project. That will
come after I get my feet wet :) I would also like to start with 38mm as
it's relatively inexpensive, yet somewhat large enough for grain
casting, etc, and nitrous requirements are modest too.
I am also planning on casting PBAN or HTPB grains. I would use
stock PVC but don't have a lathe to turn the chamfer (likely
otherwise easily managed). The difficulty is otherwise that "stock
hardware" is designed to seal primarily on the o-ring to PVC/ABS/PE
pipe chamfer. It would seem by practice that the chamfer is necessary.
Otherwise HTPB or PBAN grains give me more flexibility in compounding
grains for different effects as well as other factors such as
incorporating pre-combustion and post combustion chambers. Using
composite grains, however, requires different, though fortunately more
traditional, nozzle and floating injector sealing mechanisms. I'm not
so sure now about PBAN though as I find it very gooky and sticky at low
solids loadings and I think it might be problematic for thinner webs on
38mm motors. Perhaps more workable on 54mm grains.
For the forward closure vent orifice, Marcus Leech noted "0.015" is
what we use. That's a number 72 drill, IIRC."
That for 38mm hardware. [categorize into tech info section]
Apogee Article on simulating hybrid motors in RockSim: http://www.apogeerockets.com/education/newsletter55.asp
is an important article to read and ensure you understand. I
have in fact had a skywriting flight that I later analyzed as directly
responsible for this mass flow induced stability shift (This on an
Apogee Snarky upscale for which my version of Rocksim (6 or 7) didn't
yet do tube fins). Backing in flight data and adding tube fin
simulation hacks into Rocksim showed the instability point at exactly
where video showed it - exciting confirmation - and that validation of
the new rocksim model allowed me to compute appropriate trim of the
I've requested this direct support in Rocksim but it's pretty low on
their list (Speak up hybrid flyers!). Steve Daniels and I discussed
this and he noted that the newer Rocksim XML could support this - but
programs or scripts would need to be written to generate the modified
Project Quick Links
This primarily has my projects listed - but a few others may be
included such as the Daniels Hybrid Sky project.
Polymer Hybrid Experimental Motor
Hybrid Experimental Motor
ABS/Alcohol/Nitrous Experimental Motor
Hybrid Sky Project
Steve Daniels and his son Evan along
with Rick Faith are the primary collaborators on a 4" N Class motor.
They are personal friends and I am also contributing collatorator from
a machine shop and composite construction shop perspective.
They have a nice motor in development and are taking a very scientific
and disciplined approach to this project. They have also developed a
very fast high resolution data acquisition package. The Hybrid Sky Web Page
Resources, forums, etc.
My general Hybrids
pages have a lot of other information. Also my composites
curing, and other pages.
The aRocketForums here and links page on motors: http://users.cybercity.dk/~dko7904/motor.htm
The forums are a bit noisy - but a lot of commercial and hobby motor
builders hang out here.
is oustanding for ex and advanced hybrids. If you're serious about
ex hybrids you need to register and hang out here.
Community and forum
is a bit noisy but very knowledgeable
commercial as well as advanced hobby folks hang out there
is a good one for sport flyers. Many EX
hybrid motor builders also hang out there.
. An excellent
resource for specs and parts for HT and RATT. [But do note that he
passed away so the site is static. Use for Reference]
Projects & People
Suppliers (for Ex primarily)
. An excellent resource for specs and parts for HT and
RATT. [But do note that he passed away so the site is static. Use for
very knowledgeable, friendly, helpful.
Graphite is relatively inexpensive and I source most of mine from http://www.graphitestore.com/
US Plastics Supply -I get most of my nylon tubing here - especially for
the smaller motors (up through the 3/16" size) all sorts of plastic
stock, shapes, sheets, rods,
launch tubing, etc http://www.usplastic.com
TAP Plastics - another supplier - mentioned by whom I bought the BC
motor from; apparently similar to US Plastics http://www.tapplastics.com/
. Naturally need it be
mentioned? Almost anything. Delivered Fast.
for 9V battery holders,
brackets, switches, etc.
Doug at http://www.pratthobbies.com/
has GSE, supplies and in particular the *best* nitrous solenoids
available as they're wound for continuous duty
Cold Fusion N2O
is where I got good
prices on my 15# tank and my monster solenoid (now a monster dump
Books, Simulations etc
Hybrid Rocket Motor and
Plumbing PIPE Hybrid Fuels
|3/4" SCH 40 PVC - makes great 1"
Coring mandrel for casting 1.5" plastic pipe grains
|3/4" SCH 80 PVC
|1" SCH 40 Plastic (PVC /
ABS / ...)
|1" SCH 80 Plastic (PVC /
ABS / ...)
|1.5" SCH 40 Plastic (PVC / ABS /
|1.5" Thinwall Plastic
|1.5" ABS TriBrid Grain (regular
ABS milled thinner)
|1.5" SCH 80 Plastic (PVC / ABS /
|2" ABS DWV? (2.375 nominal OD)
|2" PVC SCH 40
|2" PVC SCH 80
Hybrid related McMaster Parts
I want to find out specs for HyperTek's flight tanks.they're not
DOT and are lighter. COTS anywhere?
From Bill Spadafora hybridrocketmotors:
From a hybrid rocket motor list page.
49 CFR 178.35 details the markings
required on DOT approved cylinders.
DOT3AA1800 is the required marking for
the DOT specification (3AA)
followed by the design pressure.
Details on the 3AA specification
No aluminum allowed and a short list of
allowable steel alloys.
The serial number is required to follow
this. 574891F I presume.
The inspectors mark and date is
required to be near the serial
Perhaps this is the other mark.
DOT3AA1800 specification cylinders are
listed as suitable for the
shipment of nitrous oxide at 49 CFR