Can we remake plastic waste into rocket fuel?

[Hobie1dog]

Hybrids use to use some type of PVC motor that was advertised by Jeff Jakob when he had his short-lived website , he lived out in California I believe but shot off big all aluminum rockets at BALLS.

 

[G_T]

PVC works as a hybrid fuel, yes...

Folks, most anything combustible works as a hybrid fuel if you design for it. That doesn't mean "most anything" is a good choice. There are solid reasons for the choices currently in use. Without doing the ACTUAL research, or at least studying the problem, speculating is just generating hot air and wishful thinking.

Ditto for solid and liquid propellants.

Gerald

 

[Grog6]

I'm pretty sure darn near anything will burn, if you mix it with AP, lol,

I used to have a white leather liesure suit with a fur collar and wide lapels.

Ditched it when I saw LSL I

 

[MidOH]

Fusion will make everything fuel:
https://www.lockheedmartin.com/en-us/products/compact-fusion.html
But for now, I'd settle on just seeing ionized hydrogen as fuel.

 

[bearnard66]

I know that some hybrid rockets use solid hydroxyl-terminated polybutadiene ( HTPB ) fuel and 90% hydrogen peroxide ( H2O2 ) liquid oxidizer.

 

[bearnard66]

Also, hybrid rockets are often used for some microgravity missions and experiments or to deliver microsatellites into orbit. Hope that in some time this type will be improved and used for more kinds of missions

 

[curtisheisey]

The real pollutant problem with rockets is that one of the AP burn products is sulfuric acid and or HCl. Using another binder/oxidizer combination that does not decay into sulfuric acid or HCl would make rockets much more eco friendly than re-using plastic waste, IMHO.

There are a number of research papers out there exploring alternative oxidizers and binders, some of which do not decay into sulfuric acid.

Glycidyl azide polymer (GAP) is one of them. Google "gap polymer rocket propellant" Also potentially higher performing than HTBP.

And for oxidizers: https://pubs.rsc.org/en/content/articlelanding/2017/gc/c7gc01928a
"It is estimated that each flight of the Ariane 5 space launcher liberates about 270 tons of concentrated HCl as well as alumina ..."
"Several promising candidates as oxidizers to substitute for AP have been developed such as phase-stabilized ammonium nitrate (PSAN), ammonium dinitramide (ADN), hydrazinium nitroformate (HNF), hexanitrohexaazaisowurtzitane (HNIW or CL-20), some molecules containing the trinitromethyl functionality or fluorodinitromethyl derivatives, polynitro-substituted pyrazoles and triazoles, polynitroazoles, tetrazole derivatives, carbamate derivatives and tetranitroacetimidic acid. These chlorine-free alternatives, which at present are being tested, can overcome most of the previously mentioned shortcomings, but at the same time bring up new challenges as it will be described later in the paper. "

Here is one on green propellants
https://www.scielo.br/j/jatm/a/mKwbtgCb5nCkDQxLCTwrkVj/?lang=en&format=pdf

 

[Steve Shannon]

The real pollutant problem with rockets is that one of the AP burn products is sulfuric acid and or HCl. Using another binder/oxidizer combination that does not decay into sulfuric acid or HCl would make rockets much more eco friendly than re-using plastic waste, IMHO.

There are a number of research papers out there exploring alternative oxidizers and binders, some of which do not decay into sulfuric acid.

Glycidyl azide polymer (GAP) is one of them. Google "gap polymer rocket propellant" Also potentially higher performing than HTBP.

And for oxidizers: https://pubs.rsc.org/en/content/articlelanding/2017/gc/c7gc01928a
"It is estimated that each flight of the Ariane 5 space launcher liberates about 270 tons of concentrated HCl as well as alumina ..."
"Several promising candidates as oxidizers to substitute for AP have been developed such as phase-stabilized ammonium nitrate (PSAN), ammonium dinitramide (ADN), hydrazinium nitroformate (HNF), hexanitrohexaazaisowurtzitane (HNIW or CL-20), some molecules containing the trinitromethyl functionality or fluorodinitromethyl derivatives, polynitro-substituted pyrazoles and triazoles, polynitroazoles, tetrazole derivatives, carbamate derivatives and tetranitroacetimidic acid. These chlorine-free alternatives, which at present are being tested, can overcome most of the previously mentioned shortcomings, but at the same time bring up new challenges as it will be described later in the paper. "

Here is one on green propellants
https://www.scielo.br/j/jatm/a/mKwbtgCb5nCkDQxLCTwrkVj/?lang=en&format=pdf

You mean hydrochloric acid (HCl).

 

[Grog6]

The acids are not the worst part of the exhaust; the cyanides are the bad part.

 

[High Desert Rocketry]

A hybrid can burn just about anything... however, commercial propulsion is usually concerned with optimizing thrust, total impulse, or both. Hybrids generally don't stack up to APCP or liquid fuels on an weight to thrust/impulse basis.

We have a used tire problem in the desert and probably all over the country. Years ago I thought about stacking them in a hybrid motor as the fuel...just watch out for steel belts out the nozzle

Lots of comments about how bad AP is for pollution. A simple solution for solid motors is KNO3. You don't need the higher impulse APCP provides unless you need to go to orbit.

 

[MJW]

Lots of comments about how bad AP is for pollution. A simple solution for solid motors is KNO3. You don't need the higher impulse APCP provides unless you need to go to orbit.

Sure would be nice if there were commercially available HPR reloads using KNO3 instead of AP. K and above would be a lot more affordable for those who don't DIY.

 

[prfesser]

Sure would be nice if there were commercially available HPR reloads using KNO3 instead of AP. K and above would be a lot more affordable for those who don't DIY.

Unfortunately such reloads would be regulated and would require a permit, storage, the whole nine yards.

Best -- Terry

 

[prfesser]

The acids are not the worst part of the exhaust; the cyanides are the bad part.

According to PROPEP, typical APCP produces roughly 100,000 times as much HCl as it does CNH (HCN isn't shown as a product...dunno why) in the chamber. No cyanides are represented in the exhaust, so if they're present they're in awful small amounts. And gaseous hydrogen chloride is quite dangerous in itself. It's so irritating that in higher concentrations the body essentially shuts off the breathing reflex.

 

[Grog6]

I think I misread the report tfrom propep; I missed the 1e-4 part.

 

[kramer714]

There's a reason why hybrid motors reached their hay day in the time of the BATF problems, then quickly died away after Judge Walton required them to follow their own rules. Now hybrids are unique because of their difficulties.

To quote the eminent ballistics scientist* M. Python, in regards to hybrids, 'I'm not dead yet'

* See bovine trebuchet analysis for ballistics testing

 

[High Desert Rocketry]

Big nitrous hybrid project (Alex) going up at BALLS on Saturday and I still make some LOX hybrids at FAR when universities have some LOX leftover from their liquid bi-propellant motors...I just bought 5 pounds of paraffin last week for one.

 

[n3tjm]

The real pollutant problem with rockets is that one of the AP burn products is sulfuric acid and or HCl. Using another binder/oxidizer combination that does not decay into sulfuric acid or HCl would make rockets much more eco friendly than re-using plastic waste, IMHO.

There are a number of research papers out there exploring alternative oxidizers and binders, some of which do not decay into sulfuric acid.

Glycidyl azide polymer (GAP) is one of them. Google "gap polymer rocket propellant" Also potentially higher performing than HTBP.

And for oxidizers: https://pubs.rsc.org/en/content/articlelanding/2017/gc/c7gc01928a
"It is estimated that each flight of the Ariane 5 space launcher liberates about 270 tons of concentrated HCl as well as alumina ..."
"Several promising candidates as oxidizers to substitute for AP have been developed such as phase-stabilized ammonium nitrate (PSAN), ammonium dinitramide (ADN), hydrazinium nitroformate (HNF), hexanitrohexaazaisowurtzitane (HNIW or CL-20), some molecules containing the trinitromethyl functionality or fluorodinitromethyl derivatives, polynitro-substituted pyrazoles and triazoles, polynitroazoles, tetrazole derivatives, carbamate derivatives and tetranitroacetimidic acid. These chlorine-free alternatives, which at present are being tested, can overcome most of the previously mentioned shortcomings, but at the same time bring up new challenges as it will be described later in the paper. "

Here is one on green propellants
https://www.scielo.br/j/jatm/a/mKwbtgCb5nCkDQxLCTwrkVj/?lang=en&format=pdf

Thinking off the top of my head, where in APCP is a sulfur atom available to produce sulfuric acid? I know APCP produces a lot of HCL.

 

[curtisheisey]

N3tJM >
Thinking off the top of my head, where in APCP is a sulfur atom available to produce sulfuric acid? I know APCP produces a lot of HCL.



I meant HCl

 

[n3tjm]

N3tJM >
I meant HCl

Oh ok

 

[prfesser]

N3tJM >
Thinking off the top of my head, where in APCP is a sulfur atom available to produce sulfuric acid? I know APCP produces a lot of HCL.

I meant HCl

I'm not aware of any APCP that contains sulfur or a sulfur compound. The chlorine is in AP, formula NH4ClO4.

 

[G_T]

Going by memory, PEP generally returns top 10 exhaust products not the full list. But I don't worry about HCN in the exhaust. There won't be much, and one shouldn't be sniffing the exhaust anyway! Smell any almond?

For hobby use, KNO3 would be fine as an oxidizer in most cases. Most flights are not min-diameter performance rockets. So going to a diameter larger and possibly longer motor for the same total impulse doesn't seem to me to be a problem. That's particularly the case given how cheap rocket candy is to make. It just has little issues like humidity and temperature tolerance compared to APCP that would keep it from being a commercial product.

Too bad Ammonium Nitrate has a bad rep and we can't get it in the form we would like to use. It gives more performance than rocket candy and also doesn't contribute undesirable Cl or (worse) Fl compounds in the exhaust. It does have issues, such as needing controlled temperature storage if not phase stabilized. And if you try hard enough or are stupid enough you can make it detonate. It also burns slowly compared to rocket candy and APCP. But you can still control the thrust profile through geometry, and the burn rate through additives. If you want fast, use a larger core longer motor compared to equivalent thrust profile APCP motor.

Pretty much any other useful solid oxidizer is going to be out of our price range.

In terms of total_impulse/$ for a reload that we could buy or make, rocket candy and relatives, N2O hybrids, and ANCP are the clear winners (ignoring water rockets) ... followed by black powder variants, followed by APCP at many times the cost. Of course N2O hybrids are not a solid propellant system. Generally systems using liquid oxidizer are much cheaper than solids for the same total impulse. I'm not talking the hardware; I'm talking the fuel and the oxidizer.

Generally the more environmentally friendly modern replacements for AP which have good performance are many times the cost of AP if you can even find them.

And nobody to my knowledge is messing with double- and triple-base propellants at this time. Not that it would fit under NFPA 1127! But nitrocellulose plus energetic stabilizers does tend to get rid of Cl in rocket exhaust and does provide good performance. It is proven technology. It just has some, ummm, scaling problems.

Gerald

PS - Don't use Teflon as a secondary oxidizer. Just don't.