Why not hybrids?

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Perhaps, but it is a dangerous approach without computing it out beforehand and probably creeping up on the Kn in a series of tests, starting rather low. If one does not maintain a sufficient pressure gradient across the injectors, then the motor can flash back to the tank. N2O under pressure at elevated temperatures IS an explosive. Under such a scenario the tank will detonate. It would be easy to get into such a scenario with what you propose.

Additionally, the flight tank pressure tends to drop during a self-pressurized hybrid burn. The pressure at the injectors is also influenced by acceleration and the remaining oxidizer mass.

I would suggest NOT trying with a conventional solid propellant grain.

A hybrid grain can include a quantity of oxidizer. But I would suggest the main reasons for doing so are to try to increase the density impulse of the motor (solid oxidizers having higher density than liquid N2O), and to try to improve the regression rate for a fuel which otherwise doesn't regress quite fast enough for the correct O:F ratio. On the minus side, the flammable fuel then becomes an energetic fuel which is quite a bit more hazardous and subject to different restrictions (shipping). Additionally, that energetic solid would no longer qualify as suitable combustion chamber insulation!

Gerald
 
AT tried a few of them N 2800 out of an M 1419 or so.
The only problem is, as Gerald pointed out: Kn and cores would have to change.
By adding the NOS, you increase the burn rate with the added Oxygen from the Nitrous.

Back in the 90's, Someone added the Whipped cream NOS cartridges to an H 97 one time.... It even worked!


JD

I still have my NOS tanks and hardware, they are almost empty but the 54mm tank still has 280gm or so in it and I do have two reloads, an I145H and I210H or something.
I was wondering if I could do an EX load with some simple APCP fuel and hit it with NOS in my 54mm AT hardware? The problem is the valves on the tank, they leak and the valve pin gets messed up.

-John
 
If you consider all the extra weight of the hardware, the performance of the smaller hybrids is much lower than that of a comparable solid. You have to be in the L and above range to see any real gains or benefits.


JD
That does not have to be the case. A hybrid should be able to outperform a solid if optimized, but few are because the kinetics and internal fluid mechanics are complicated. Current propellant bore configurations are not optimized as the Kn for a hybrid is quite different than that for a solid due to kinetics. Additionally current hobby hybrids do not utilize mass flow controlled nitrous injection to mitigate the deleterious temperature effects on Nitrous injection rates.

The larger you go, the larger the advantage of the hybrid, especially in terms of propellant cost. Hot rod nitrous was around $4 a pound the last time I checked with industrial nitrous supply costs significantly less. In theory, nitrous is not regulated, and is in general, available anywhere if you arrange for it ahead of time.

The best fuel IMO is a hydrocarbon wax. It's basically solid kerosene. With an appropriate opacifier, it can be vaporized efficiently, and should behave similar to a premixed liquid motor without the startup headaches of a liquid. And wax is cheap and easy to form. Sugars can also be used as fuels that are similar to alcohols, and sugar is also cheap.

I believe there is a lot of room for innovation in EX hybrids but 99% of the EX folks would rather mix, pack and launch rather than have to haul a GSE with a nitrous tank out the launch pad and ponder about the finer details of fluid mechanics and hybrid kinetics. Those 1% of the diehards who want to be different could make some major innovations if they work at it. The unfortunate fact is that the economics of high power rocketry is limited by market size so IMO big hybrids will never make economic sense for a commercial manufacturer, while they make a lot of sense for the EX community.

Bob
 
I spent some time computing out (not finalized) a full M EX hybrid. It is in 88mm, whereas I would do it in 75mm most likely for solids. The recovery mass can be reduced down to a comparable value to a solid motor of the same total impulse, without resorting to composites. It is an interesting motor and I'd like to make and burn it sometime.

Gerald
 
I have read Bill Colburn's book "A Manual for Hybrid Propulsion Design." I am wondering if there are other hybrid motor design reference materials that Forum folks could recommend. I see these 2 books available. Anyone read them and can comment? And, I have and will continue to research on Google. Thanks for your feedback.

StanO

9783659158131_p0_v1_s260x420.JPG
9781563477034_p0_v1_s260x420.JPG
 
I have read Bill Colburn's book "A Manual for Hybrid Propulsion Design." I am wondering if there are other hybrid motor design reference materials that Forum folks could recommend. I see these 2 books available. Anyone read them and can comment? And, I have and will continue to research on Google. Thanks for your feedback.

StanO

9783659158131_p0_v1_s260x420.JPG
9781563477034_p0_v1_s260x420.JPG

I used Fundamental of Hybrid Rocket Combustion & Propulsion quite bit about 13 years ago. Before that was George Sutton's Rocket Propulsion Elements that had a chapter dedicated to hybrids. The version I have is whatever was current in '95 or so. I remember taking it to my high school math teacher looking for some help with, well, the math. AIAA has a bunch of technical papers on hybrids but they can be costly and it's hard to know just how useful they'll be until you buy them. That's the way it was many years ago so things may have changed.

I'm not familiar with the book Hybrid Rocket Combustion, but knowing nothing about it I would still buy it based on the title alone if I was still knee deep in design.
 
Karl,

You are probably write in the long term, but there is a significantly higher start up for a club.


I think you are talking about cost. You are correct that getting started in hybrids is a significant investment. You really need your own GSE on the pacific coast and I assume it is the same elsewhere. I am considering marketing good reliable GSE that has everything you need or customized to your needs including a vent sensor. It would also be nice to have a website made up that had hybrid training so people can have success.
I made my own GSE and it cost me less than $300 altogether. Motor cases tend to be more expensive too but not by more than 50%. The real savings is in the reloads. I make my own reloads. Smaller motors H to K are in the $5 to $10 range. M motors are expensive they are like $25 to make. Of course you need nitrous which is $30 for an M motor. So in the end I have made a lot of nice hi power flights at a fraction of the cost of solid motors.
 
I think you are talking about cost. You are correct that getting started in hybrids is a significant investment. You really need your own GSE on the pacific coast and I assume it is the same elsewhere. I am considering marketing good reliable GSE that has everything you need or customized to your needs including a vent sensor. It would also be nice to have a website made up that had hybrid training so people can have success.
I made my own GSE and it cost me less than $300 altogether. Motor cases tend to be more expensive too but not by more than 50%. The real savings is in the reloads. I make my own reloads. Smaller motors H to K are in the $5 to $10 range. M motors are expensive they are like $25 to make. Of course you need nitrous which is $30 for an M motor. So in the end I have made a lot of nice hi power flights at a fraction of the cost of solid motors.

Karl - You should start a thread or two on your work; say a GSE thread in the ground support forum, and a hybrid motor design thread in the research forum. I for one would love to know what you have learned, especially where GSE is concerned.
 
Karl - You should start a thread or two on your work; say a GSE thread in the ground support forum, and a hybrid motor design thread in the research forum. I for one would love to know what you have learned, especially where GSE is concerned.

I agree. I may be able to offer some advice; good and bad...
 
For me, rocketry is about setting new goals and striving to reach them. Sort of like, "why did the man climb the mountain? Because it was there." When I do choose to invest in and fly hybrids it won't be because of the cost or performance. It will be because I want to add them to my repertoire.

I have seen some great hybrid flights, and some of them were probably Karl's.
 
Karl,

I would say there is a market for up to 10 GSEs in Germany alone at this point. Considering the strong interest in France and Italy too.

Now some ideas/questions/experience

1) I will add to my youtube page ("altimaxfresser", only hybrids) some videos about how to setup the hardware at launches. Shall be online end of month.
2) Bob wrote: "The best fuel IMO is a hydrocarbon wax". This sound good to me but I am not sure if this is the same as paraffine?
3) my 2 cents for a sucessfull/easy hybridz design: use standard components. I must really say, I admire contrail for that, just using Parket presslocks and tubing, you can get that anywhere & replace after burn
4) I personnaly prefer my 75mm hardware: it is simply much faster to prepare and clean later. And good for my fat large fingers :))
5) I would agree with some statements here: propose a dedicated page on self made reloads for hybrids. I believe we do not violate any laws anywhere but this would offer so much exciting opportunities. I would love to try my own mixes. I have collected so far different recepees in the world (even from former soviet rocket designers -no jokes-) and I would be happy to share and discuss.
6) who said you can fly with a salami as reload??? true or not?

Denis
 
I've received multiple reports that the salami did fly, and smelled sort of like peperoni. It might have been frozen before the flight. However, people might not have been telling me the whole story!

Parrafin is a hydrocarbon wax but there are others. It is often used for candles and also for sealing jars IIRC. The carbon chain length is between 20 and 40 for parrafin I believe.

Wax essentially solves the regression rate problem due to the way it forms waves on the surface which blow off molten drops to evaporate and burn in the gas mix. So it dumps fuel into the combustion flame faster than most any other solid fuel for the same core geometry and flow conditions. As I understand it, things to watch out for are: (1) Opacification - wax is transparent enough that it can melt fast and deep, clog the nozzle, and boom. Charcoal, RIO, TiO2, etc, can be used to solve this. (2) Wax is mechanically weak so watch out for high-G flights. I understand a larger commercial motor worked on the test stand but not in flight due to this. But that's from piecing together incomplete and possibly incorrect info.

I am rather interested in hybrids and always have been. I was going to cert L3 with hybrids but ended up doing it with solids. All I do now is EX. But in any event I have no GSE. The only hybrid flight I've done was with a Contrail M using borrowed GSE (we borrowed a hybrid person for their expertise and got the GSE for the flight in the process). I'm primarily interested in EX hybrids in the M range and larger (say, 3 to 6" diameter motors) so I'd certainly like to see what others have done. I've probably grabbed about everything off the web that is available, studied some texts and plenty of papers on the subject, and would like to make and fly some motors.

I don't have GSE though. The group I fly with is not so interested in lugging around a tank but that is likely what it will eventually come to. In any event it is practical at the launches I have in mind, as one can drive to the away cells so mving the tank around isn't too big a deal. I'd certainly like to see a thread on GSE configuration and parts lists, as well as a thread on EX hybrids and a thread on hybrid test stands for larger motors.

Gerald
 
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If you just want to pay someone to make the GSE, Doug Pratt is good possbility. Take a look at his Valve Manifold for a COTS solution. It's $300 w/o tank.

https://pratt-hobbies.com/products.asp?cat=9

This is an hour long presentation at Stanford about hybrid rocket motors. About half the talk discusses wax.

https://www.youtube.com/watch?v=o9erCLJ5KVg

A practical problem with wax is that the burn times get too short. Supposedly adding things like glue sticks or steric acid will mitigate some of the structural issues. I've never worked with wax so I have no comments.

-->MCS

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I have poured paraffin grains that had wire mesh coiling away from the mandrel spiraled out to the casting tube. Nylon mesh works well, as does the steel or aluminum mesh (which will burn efficiently in a hybrid). Higher temp hurricane wax work as well. I have tried toner powder to opacify a grain, but the toner will not blend with the wax. Carbon balck works best. Wax tends to shrink when cooled, so spining the grain will allow the fuel to cool and shrink away from the core, and not the casting tube.
 
I've received multiple reports that the salami did fly, and smelled sort of like peperoni. It might have been frozen before the flight. However, people might not have been telling me the whole story!]

I tried it with a pepperoni in a Caldera Micro Hybrid. I had to freeze the pepperoni to be able to drill the core. The Quickburst Twiggy I used to ignite it didn't melt the burst disk. I'm not sure why. I wish I recorded it because the Twiggy was hot enough to melt the grease in the pepperoni and it just dripped out of the nozzle. I've got to try it again.


I'd certainly like to see a thread on GSE configuration and parts lists

I've got relatively simple wireless GSE for monotube hybrids but no documentation. I'll get some pictures at our next launch.


a thread on hybrid test stands for larger motors.

Here's a picture of the vertical test stand I built for NAR S & T. It's the tall thing in the middle of the clutter in my workshop.

IMGP0697.jpg
 
Karl - You should start a thread or two on your work; say a GSE thread in the ground support forum, and a hybrid motor design thread in the research forum. I for one would love to know what you have learned, especially where GSE is concerned.

Very well then I will make a video and a schematic of the GSE I made and publish it on the forum. My son and I will be working on a vent sensor because as of right now the one I use is OOP. I find the vent sensor very helpful because I normally cannot see the vent plume.

As far as motor design all I have done is make fuel grains but I have some interesting results. That will have to be on the research forum. I just need to get approved to enter.
 
Can those of you with experience flying N2O hybrids K or larger give me an idea of the N2O loss during fill at the pad and fire? If one were to attempt to get, say, roughly 12# of N2O into a flight tank at the pad, roughly how much N2O would really be used? 12# should be a full M, roughly speaking. 50% extra for loss? More, or less? How does that scale with motor size? Linearly, or is less lost (%) for larger motors?

Looking at tanks... And hybrids M and larger.

Thanks,
Gerald
 
Very well then I will make a video and a schematic of the GSE I made and publish it on the forum. My son and I will be working on a vent sensor because as of right now the one I use is OOP. I find the vent sensor very helpful because I normally cannot see the vent plume.

As far as motor design all I have done is make fuel grains but I have some interesting results. That will have to be on the research forum. I just need to get approved to enter.

Sounds great Karl, I will be watching for the threads... Thank you!
 
Can those of you with experience flying N2O hybrids K or larger give me an idea of the N2O loss during fill at the pad and fire? If one were to attempt to get, say, roughly 12# of N2O into a flight tank at the pad, roughly how much N2O would really be used? 12# should be a full M, roughly speaking. 50% extra for loss? More, or less? How does that scale with motor size? Linearly, or is less lost (%) for larger motors?

Looking at tanks... And hybrids M and larger.

Thanks,
Gerald

Gerald I am assuming that you are looking at ground tanks and not flight tanks. I suggest that you get a minimum 20 pound tank. Keep in mind that even though the Tank holds 20 pounds you cannot use all of it and expect liquid. I refill mine if it is under half full. If you have a 12 pound flight tank you will want a full 20 pound ground tank. The capacity of the Contrail 3200cc flight tank is about 5.3 pounds. I do not have real scientific data but I think you loose a little nitrous just cooling the flight tank if it is above room temperature. You are also loosing nitrous between when the flight tank vents liquid and ignition. I don't have any real recorded data but I would say that I use up to 6 pounds on the Contrail 3200. One thing you will need to do is have a flow restrictor on your vent. Something like a .016 inch oriface. This will keep you from loosing excess nitrous. Commercial motors come with these built in. The Contrail 3200 uses an exterior restrictor.
 
Very well then I will make a video and a schematic of the GSE I made and publish it on the forum. My son and I will be working on a vent sensor because as of right now the one I use is OOP. I find the vent sensor very helpful because I normally cannot see the vent plume.

As far as motor design all I have done is make fuel grains but I have some interesting results. That will have to be on the research forum. I just need to get approved to enter.

Much appreciated. I'm looking forward to it.

StanO
 
sorry but this sucks a little bit. Non US citizen have no access to the research forum. US ITAR ....
I understand the why but despite all my postings, youtube videos, authorizations, levels and accreditations I have to stay outside. Especially as hybridz reloads are fully inert this does not make any sense.

Not really enjoyable. Maybe the non US shall think about a restricted hybrid forum hosted in EU.
 
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There can be interesting stuff to find in the Research forum of course. But hardly any of it has anything to do with hybrids. On the flip side, there are books and chapters of books dedicated to hybrids. There are a moderate number of freely available professional papers on the web. The material one can get one's hands on can keep one occupied for quite a while. Heck, I forget where, but there is an article of some length on the requirements, development, and design of a commercial scale hybrid strap-on booster - way beyond Q range. There's lots to find. It just takes lots of digging.

Things you would be looking for to develop your own fuel:

O:F ratio - PEP code can help you figure that sort of thing out. Plus, if you provide the design pressure it provides a good estimate of the combustion temperature, liquids and particulate percentage in the combustion chamber and the exhaust (with some major caveats), chemical species in the combustion chamber, chemical species in the exhaust, that sort of thing. One could design high smoke, low smoke, look at temperature and exhaust species and get an idea of the spectral signature and intensity of the flame. Probably lots of etceteras here.

Possible chemicals for the fuel - PEP code, and check the chemistry to make sure it is stable in storage, etc.

Regression rate of various fuels - Web research.

Mechanical issues with fuel grains - rather similar to mechanical issues with propellant grains and there are papers and chapters in books on that subject.

Opacification - It's a bit spotty but there are papers on that sort of thing.

Combustion mechanisms - Chapters of books and research papers.

Etc.

Gerald
 
sorry but this sucks a little bit. Non US citizen have no access to the research forum. US ITAR ....
I understand the why but despite all my postings, youtube videos, authorizations, levels and accreditations I have to stay outside. Especially as hybridz reloads are fully inert this does not make any sense.

Not really enjoyable. Maybe the non US shall think about a restricted hybrid forum hosted in EU.

You can join one of the oldest running hybrid yahoo groups; Hybrid Rocket Motors They have lots of good info, including a hybrid design program developed by the owner of SkyRipper Systems... the program is based off of Dr Bill Colburns Hybrid Design Manual. As Gerald has pointed out, there is a huge amount of info to be pulled from the internet. As for the research forum... a hybrid topic rarely gets read, as many are there to learn solids, therefore most hybrid topics go unfinished or never really develope discussion at all. Essentially, you are not missing much by being refused entrance. Except for direct design specifics, there is still much that can be discussed right here on this thread, for as you stated, much of the hybrid fuels used are inert.

If you wish to discuss more indepth research topics, try the yahoo group... lord knows they need to be stirred back into lively conversation.
 
sorry but this sucks a little bit. Non US citizen have no access to the research forum. US ITAR ....
I understand the why but despite all my postings, youtube videos, authorizations, levels and accreditations I have to stay outside. Especially as hybridz reloads are fully inert this does not make any sense.

Not really enjoyable. Maybe the non US shall think about a restricted hybrid forum hosted in EU.

I have never understood the self-imposed restriction on discussing _legal_ activities. Having said this.. there has been no discussion of hybrids in the Research forum for a very long time. You're not missing anything.


I don't know of any active hybrid forum on the Internet. Yahoo!Groups is probably the best bet, but the group has been dead for a long time. Arocket (https://www.freelists.org/list/arocket) is another possibility. Although arocket has been quiet too.


-->MCS

.
 
I have never understood the self-imposed restriction on discussing _legal_ activities. Having said this.. there has been no discussion of hybrids in the Research forum for a very long time. You're not missing anything.


I don't know of any active hybrid forum on the Internet. Yahoo!Groups is probably the best bet, but the group has been dead for a long time. Arocket (https://www.freelists.org/list/arocket) is another possibility. Although arocket has been quiet too.


-->MCS

.

Yes, arocket. I subscribed to that for many years and it was very active discussing a number of things, hybrids included. I stopped around 2005 or so, so I have no idea how active it still is. I seem to recall that the old Armadillo Aerospace team was fairly active there, particularly John Carmack. There were several very knowledgeable people but again I'm not sure of its' current state. It's worth a shot.
 
Yes, arocket. I subscribed to that for many years and it was very active discussing a number of things, hybrids included. I stopped around 2005 or so, so I have no idea how active it still is. I seem to recall that the old Armadillo Aerospace team was fairly active there, particularly John Carmack. There were several very knowledgeable people but again I'm not sure of its' current state. It's worth a shot.

It's reasonably active, but I see more pure discussion than discussion of creations. And more liquids than hybrids.
 
The best fuel IMO is a hydrocarbon wax. It's basically solid kerosene. With an appropriate opacifier, it can be vaporized efficiently, and should behave similar to a premixed liquid motor without the startup headaches of a liquid. And wax is cheap and easy to form. Sugars can also be used as fuels that are similar to alcohols, and sugar is also cheap.
I agree. Here's a post I made somewhere online back in 2010 (I saved it in a txt file which is why I still have it) with links which might still work. I've got a bunch of stuff on this in a subdirectory, including a few tested wax/additive formulations:

---------------

I've read in the various reports I've linked to below that the Stanford group is using what is commonly referred to as "hurricane wax" as the main component of their SP-1A fuel. So, I went looking for the characteristics of that wax and found IGI-1260, a common hurricane candle wax:

https://www.igiwax.com/downloads/tis/1260.pdf

Since I've read that shrinking of the wax grain during grain casting can be problematic, I noticed the high-temp (just as high-temp as hurricane wax), low-shrinkage petroleum/synthetic wax mix, IGI-4761, and wondered if this might provide at least a partial answer to the grain shrink problem:

https://www.igiwax.com/downloads/tis/4761.pdf

https://www.igiwax.com/downloads/tis/4761B.pdf

IGI-4761 has physical characteristics that are nearly identical to IGI-1260, but it shrinks much less during cooling. Although IGI doesn't mention the low-shrink property of IGI-4761 in the PDF above, this candle wax site does:

https://www.lonestarcandlesupply.com/wax.html#IGI-4761

They claim that IGI-4761 is a "Low Shrink Votive Candle Blend" that, consequently, "requires only one pour."

This group seems to be successful at pour casting hurricane wax grains:

https://psas.pdx.edu/FuelGrain

But they do mention experiments with spin casting like that done by the Stanford people:

https://psas.pdx.edu/ParaffinSpinCasting?action=AttachFile&do=get&target=forthspincasting.pdf

Those spin-cast grains don't look too successful to me and actually look inferior to the grain photo shown on their page covering the simpler pour casting method.

I'd like to request the posting here of recommendations/experiences relating to paraffin grain casting techniques. I'd also like to see grain opacifier recommendations/experiences with respect to ease of use, uniformity, resistance to stratification, etc.

Finally, I'd like to see a topic or forum section for the posting of links to free technical data and reports on the web relating to hybid rockets. I'll give it a start with the following links that I've found over the last few days. As a note to those on dial-up connections, most of these files are in the multi-megabyte file size range:

A nice Aviation week article on Stanford's paraffin hybrids:

https://www.stanford.edu/~cantwell/AviationWeek_Feb20_03.pdf

Stanford paraffin fuel paper and patent:

AIAA 2003-6475 "Scale-Up Tests of High Regression Rate Liquefying Hybrid Rocket Fuels":

https://www.stanford.edu/~cantwell/AA283_Course_Material/AA283_Course_Notes/Reno_paper2003.pdf

United States Patent 6880326 - "High regression rate hybrid rocket propellants and method of selecting":

https://www.freepatentsonline.com/6880326.html

Stanford hybrid presentation:

AA283 - Aircraft and Rocket Propulsion - Chapter 11 - Hybrid Rockets

https://www.stanford.edu/~cantwell/AA283_Course_Material/Ch_11_Hybrid_RocketSlides.pdf

US Air Force Academy Paper - "Testing of Paraffin-Based Hybrid Rocket Fuel Using Hydrogen Peroxide Oxidizer":

https://www.usafa.af.mil/df/dfas/Pa... Using Hydrogen Peroxide Oxidizer - Brown.doc

NASA report - "System Modeling and Diagnostics for Liquefying-Fuel Hybrid Rockets":

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040030497_2003072415.pdf

Other interesting papers/patents:

"Optical Studies of Combustion Chamber Flame in a Hybrid Rocket Motor":

https://hybrid.ualr.edu/papers/optical_combustion_chamber_study.pdf

"Laboratory Scale Testing of Nitrous Oxide – Hydrocarbon Hybrid Rocket Propellants for Small Launch Vehicle Applications":

https://www.zigaero.com/blog/docs/AbstractReno2006.pdf

AIAA 92-3301 "Results of Labscale Hybrid Rocket Motor Investigation":

https://users.rowan.edu/~marchese/rockets05/paper2.pdf

"The Performance of a Hybrid Rocket With Swirling GOx Injection":

https://www.itam.nsc.ru/users/libr/eLib/confer/ICMAR/2002/part_1/leets.pdf

United States Patent 5101623 - (Hybrid) "Rocket motor containing improved oxidizer injector":

https://www.freepatentsonline.com/5101623.html

"Design, Optimization, and Launch of a 3” Diameter N2O/Aluminized Paraffin Rocket":

https://pdf.aiaa.org/GetFileGoogle.cfm?gID=34110&gTable=Paper

AIAA 97-2802 - "Development Work on a Small Experimental Hybrid Rocket":

https://www.aeroconsystems.com/ts_pics/Grosse_AIAA-97-2802.PDF

"Introduction to Hybrid Design":

https://www.aspirespace.org.uk/aspireold/TechSeries/Introduction to hybrid design.pdf

"The Physics of Nitrous Oxide":

https://www.aspirespace.org.uk/aspireold/TechSeries/The physics of N2O.pdf

And, although it's not a hybrid, here's an interesting, 157 page technical report to DARPA on a non-cryogenic liquid fueled rocket engine:

GASL TR No. 387 - "The Nitrous Oxide - Propane Rocket Engine"

https://handle.dtic.mil/100.2/ADA393448

On general rocketry technologies, the entire online collection of Penn State's Propulsion Engineering Research Center Symposium papers can be found here:

https://www.psu.edu/dept/PERC/
 
Thx Winston. A great collection of links that need to be digested first *lol*

Thx also to all that have manifested sympathy for the EX hybrid cause, from a non US point of view.
I do not see either any reasons to hide ourselves here or anywhere else. Hybrids EX reloads are simply not compatible with political paranoia of any kinds. This is our chance.
 
Back about 2005 I witnessed my first paraffin hybrid flight; a local hybrid guy coverted an Aerotech case to use hor hybrids, and topped it with a 440cc tank. The design was a fill at the flightline and carry to the pad. He shocked us all with his instant ignition design. It was the most beautiful hybrid flight I had ever seen at a research launch. He and I managed to hook up, and he helped me design a 76mm paraffin hybrid. We managed one test firing before our friendship disolved, and here is the video from that one and only session... note that there is no warm up to ignition, when he pushed the button, the motor was ON! The sound to the video was lost, just know that this motor was loud as heck.

https://www.youtube.com/watch?v=ysbdzi3c-9Y
 
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