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:
NEW: 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
1 and
Page
2.
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
Manual for Hybrid Propulsion Design" and am reviewing it. The CD
that comes with it also has a wealth of information.
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.
The
Yahoo
group "hybridrocketmotors" is a good one for sport flyers.
The
Hybriddyne
forum is good for ex and advanced hybrids.
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.
I have a set of Propulsion Polymer 38mm hardware but I am loath to use
it for EX. The main reason is that a second run of hardware is planned
but not
scheduled, so I don't want to damage the one set of closures for which
I have 3 tubes for. They're not o-ring closures so aren't easily
replaced at this time.
My current thought is to use most of the parts from a
Sky Ripper Hybrid Motor
and just get different nozzles and floating injector made. For cast
grains like I'm thinking I'd want the casting tube / liner type model
like for regular motors. For that I'd need modifications to the
floating injector as well as a different nozzle. The parts come down to
- Case - I believe Loki makes the cases for SkyRippers so it's
probably their standard case, maybe different length, but ID compatible
- Nozzle - The SkyRippers nozzle doesn't have the liner recess so
I'd probably buy a Loki 38mm nozzle to get the liner recess
configuration
- Floating Injector- The Skyrippers floating injector doesn't have
the liner recess so I'd have Loki mill one or go the Galejs route and
make one from a Loki forward closure. (Galejs used AMW hardware). The
main issue here is milling and / or threading the part.
- Forward closure. The issue here is the vent and too big of a vent
is an issue, yet small vents are problematic. I will either buy a
SkyRippers vent or fit a pre-machined orifice (per aRocket supplier
references) to a Loki forward closure.
Given that, it seems a toss up whether to buy a complete SkyRippers
motor and have other parts made, or whether to source just the vent
from Skyrippers and get the rest from Loki and perhaps additionally a
machinist.
I talked to Woody, of Purple Woody, and he's part of Sky Rippers
(go figure!).
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.
Another Hybrid EX Experimenter, Scott Fintel; more to be
incorporated,
http://www.thefintels.com/aer/hybridmotor.htm
Apogee Article on simulating hybrid motors in RockSim:
http://www.apogeerockets.com/education/newsletter55.asp
Alberto Gassol's PVC Hybrid Rocket Engin Page:
http://www.intertlan.com/cohetes/hybrids/
Robert Galejs
Ellis Mountain
Based Experimental Hybrid Motor:
http://www.cmass.org/member/Robert.Galejs/hybrid.html
UK Rocketman - Hybrid Rocket Science Page - good intro:
http://www.ukrocketman.com/rocketry/hybridscience.shtml
The aRocket links page on motors:
http://users.cybercity.dk/~dko7904/motor.htm
There is a group on the micro hybrids which are effectively
experimental.
Bill Colburn's new book at Aerocon "
A
Manual for Hybrid Propulsion Design"
Rational Technology Hybrid Design Program:
http://www.aeroconsystems.com/literature/HDP.htm
Sky Ripper Systems Motors:
http://www.skyrippersystems.com/
US Plastics Supply - 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/
via experimentation.
You can use .25-.35 as a starting point
for Cd for a U/C valve with N20.
I've posted the 'last' update (1.6) to
the HDS web page.
here and there.
