Experimental Hybrid Rocket Motor Research

Hybrid 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:

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.

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 and 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

This 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 tube fin)

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 XML data.

Project Quick Links

This primarily has my projects listed - but a few others may be included such as the Daniels Hybrid Sky project.

HyperTek Hybrid Experimental Motor

I am flying this. Specific details are on my HyperTEK Experimental Motor Research page.

Propulsion Polymer Hybrid Experimental Motor

I am flying this - which is good as this sweet motor is now out of production. Specific details are on my Propulsion Polymer 38mm Hybrid Experimental page.

RATTWorks 29mm Hybrid Experimental Motor

Specific details are on my RATTWorks 29mm Hybrid Experimental page.

RATTWorks Tribrid ABS/Alcohol/Nitrous Experimental Motor

Specific details are on my RATTWorks TriBrid Hybrid Experimental page.

Daniels' 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.

Other Links

Resources, forums, etc.

My general Hybrids and my EX Solids 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.

The Hybriddyne forum is oustanding for ex and advanced hybrids. If you're serious about ex hybrids you need to register and hang out here.

The "ARockets" Community and forum is a bit noisy but very knowledgeable commercial as well as advanced hobby folks hang out there

The Yahoo group "hybridrocketmotors" is a good one for sport flyers. Many EX hybrid motor builders also hang out there.

Now Hybrids.com. 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

The Daniels Hybrid Sky Web Page.
Scott Fintel's Experimental Rocketry

Suppliers (for Ex primarily)

Now Hybrids.com. 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]
Aerocon Systems. Bob is 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/
McMaster. Naturally need it be mentioned? Almost anything. Delivered Fast.
MissleWorks 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 solenoid)

Books, Simulations etc

Fundamentals of Hybrid Rocket Combustion and Propulsion is an excellent resource
Bill Colburn's book at Aerocon "A Manual for Hybrid Propulsion Design"
Rational Technology Hybrid Design Program: http://www.aeroconsystems.com/literature/HDP.htm
Steve Daniel's HSIM package
Todd Moor's HDAS

Hybrid Rocket Motor and Injector Patents

Page of patent searches and finds related to hybrid rocket motors and injectors.

Plumbing PIPE Hybrid Fuels

Pipe Description
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
19" 1.80"
1.5" ABS TriBrid Grain (regular ABS milled thinner)
1.5" SCH 80 Plastic (PVC / ABS / ...)
2.360 ... 2.390
2.0 ... 2.050
2" ABS DWV? (2.375 nominal OD)
2.365 ... 2.380 2.375
2.0 ... 2.050
2" PVC SCH 40
2" PVC SCH 80

Hybrid related McMaster Parts

High Pressure one way check valves - 1/4" 3000 PSI  46105K39
Now hybrids has a RATT resource page with McMaster part numbers. It's here.
Portland State Aerospace Society PSAS Home Page  They're working on was hybrids


Tank Information

I want to find out specs for HyperTek's flight tanks.they're not DOT and are lighter. COTS anywhere?

From Bill Spadafora hybridrocketmotors:

AT and Alpha use paintball tanks like these:


They meet this specification:


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 are at:


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 number.
Perhaps this is the other mark.

DOT3AA1800 specification cylinders are listed as suitable for the
shipment of nitrous oxide at 49 CFR 173.304a