Paraffin Vs Dextrin in a BP propellant mix.

[MinamotoKobayashi]

Hello.

I have just prepared 800 grams of ballmilled BP for my new experimental nozzleless big rocket.

I ballmilled the chems soaked in ethyl alcohol for safety matter, together 5% dextrin and 2% of mix 50/50 paraffin wax/turpentine.

I also added 10 grams of KP every 100 grams of BP to further improve the performance (the rocket must lift an 8" shell and

probably also a 10" shell later, so I need a lot of thrust).

The resultant syrup was dried and 20 mesh granulated.

Now I'm in doubt if I must slightly re-wet the powder with turpentine before to pack it at 7000 PSI into the rocket.

Also I wish to know if it could be a good idea to use also a little bit of water to also activate the dextrin

to have two benefits, the wax and the dextrin.

Lately I can dry well the whole rocket inside my dehydratator at 70°C for two hours

Anyone has any idea if this procedure will be ok?

Edited August 18, 2019 by MinamotoKobayashi

[pyrokid]

A few points:

 

1) Dextrin is activated with water, so I don't think it serves much purpose in your formulation.

2) Black powder is known to burn faster when it contains a small fraction of water, like from ambient humidity. I'm not sure if your dehydrator treatment will yield the best results.

3) Dextrin bound granules can make consolidation of the fuel grain challenging. In some cases, the grains are too resilient, and voids are left in the fuel grain.

4) Rocket motors subjected to multiple environmental fluctuations are known to lose reliability. Treatment in a drier makes me nervous.

5) You may want to research the process of "tube waxing," where a thin coating of wax is applied to the inner surface of the rocket tube before pressing. I've never tried it, but proponents of the method claim that it makes the motor more tolerant of variations in process and storage parameters.

[MinamotoKobayashi]

Hi Pyrokid, thanks for Your reply.

 

Yes dextrin is activated by water, and this is the motive that I wanted to slightly wet the 20 mesh powder before packing it at 7000 PSI into the tube.

 

20 mesh grains are the classic "meal" format, that is the kind of BP always used in BP powered motors. The grains are so small that packing it at

7000 PSI surely do not create any trouble. If there is also a little bit of humidity, the problem will not exist, the resulting packed fuel will be hard like a stone.

 

The wax in the BP has a different purpose compared to the classical tube waxing procedure (that usually I do in every cardboard tube).

In fact there are many different schools of thought how to consolidate at the best the BP inside a rocket.

One of them is use only water, another is use 2% of paraffin wax diluted in turpentine mixed into the BP.

 

My thought is: if it is possible to use both the metodology at the same time?

 

By the way: I will use a 2mm aluminum tube for this big rocket, not a cardboard one, so I haven't the necessity to wax the inside walls of the tube.

Edited August 18, 2019 by MinamotoKobayashi

[Arthur]

" rocket must lift an 8" shell..."

 

NO! You must design and test the rocket to prove that it will lift your intended payload, and lift it quickly enough for aerodynamic stability to be achieved before it leaves the launcher. https://www.youtube.com/watch?v=5g9uCcY7tFg is a vid of something a little larger with a very large and powerful motor and a huge stick. Remember that the stick will land somewhere like a dart and pierce any building or vehicle or person that gets in the way -he had a lot of desert to fly his rocket.

 

One significant reason for abandoning a rocket as a shell launcher is the amount of falling debris. A lift cup left in the mortar leaves a lot less debris than a motor case and stick at 1000feet.

[NeighborJ]

Mixing and matching methods don't usually improve anything.

 

Dextrin is not needed in any rocket fuel, it will only slow the burn. The water serves the purpose of a compaction aid. If you use the 1-2% water it will not need a binder but should be launched soon to avoid tube relaxation. Most of the time this isn't a problem but it can be an issue if the motor is operating near redline. If a motor is allowed to dry out the fuel gets hotter and changes the burn rate. I don't store water wetted motors because of this possibility.

 

Granulating fuel with 1.5-2% paraffin wax dissolved in petrolium solvents skirts around the tube relaxation issue but at the expense of a slight loss of burn speed. I like this method because I can store my motors indefinitely and they perform exactly the same after 1year of storage as the day they were pressed, consistency trumps power in my experience.

 

In the end it is the builders responsibility to decide what he expects to achieve, do the appropriate testing and make an informed decision there arent any wrong answers. 8" ball shells are an entirely realistic goal for a 6lb BP motor but a 10" is really pushing its capability to deliver safely and reliably.

[MinamotoKobayashi]

Arthur, You talk to me as if You had in front of You a noob. I'm not a newbye, I have posted tons of tutorials and I use rocket headers since three years and I already lifted a 8" shells using 3x rockets using granulated r-candy mix, a well-tested method that I created and perfected a lot of times ago.

I always use my rockets in a very open spaces, I always use a solid self-builded rocket launcher with variable tilt, and I always pick up the falling debris the day after.

For 2,3,4 and 5" shells I use waxed papercard tubes. For 5" shells I use also a little charge of flash, so the second delayed burst destroy the rocket in many harmless pieces.

For 6" and 8" shells I use reusables aluminum tubes that I rescue the day after for subsequent reuse: in that way I save some moneys and I keep the environment clean.

I already launched heavy dummy shells to test my rockets daylight, I cannot see the problem if I launch it alone in the middle of a wasteland far away from me!

I'm also a fan of counterbalancing, usually I use more than one stick to keep the trajectory balanced and linear (also to avoid the dangerous spiral effect that can break the stick),

and I'm not satisfied until I reach the center of gravity in the middle of the rocket!

The video that You have sent me is one on my favourite since many months

 

x NeighborJ: thanks as usually.

But ... it is obvious that my BP will contain 5% of dextrin: when I granulate the -20+8 BP, the saved meal will contain dextrin anyway!

 

Now the powder is completely dried and it is ready to be packed. It already contains a finely ballmilled paraffin 50-50 wax+turpentine.

I need to slightly wet the powder with turpentine before packing it?

 

I will use a special custom toolset made by Zmuro ... it's a little bigger than the six pound engine.

Here are the pics:

 

 

 

 

And this is my last creation with this tool using granulated r-candy mix to lift a 8" shell: it works,

but I need to reach an higher altitude. This is the reason that, for this kind of shell, I switched

to BP powered with a little amount of KP, as NeighborJ suggested me:

 

At the end of every stick I placed a further weight of 10 grams to obtain the counterbalance in the middle of the rocket.

I used the self-adhesive weights that are usually used to balance car wheels

The sticks were first glued with hot glue and then firmly locked in place with many turns of gummed paper,

they certainly cannot be detached!

Edited August 18, 2019 by MinamotoKobayashi

[justvisiting]

MinamotoKobayashi, that tooling is beautiful! The rocket too. My largest rockets are long-spindled 3lb nozzleless BP rockets. Recently I have been making some rockets with water-wetted propellant, but I cannot find where I posted about them. I used 2 1/2-3% water. The interesting thing I found is that in normal storage over a month, the rockets do not lose any water weight! The last batch of 14 motors 12" long lost less than a gram each. They were pressed to 7500psi in waxed tubes. 3 of them had nozzles. The propellant grain is very dense and hard with this much water.

 

https://www.youtube.com/watch?v=Wshqghg4NUY

 

 

This is a six inch ball shell lifted with one of them. The total rocket weight was 2095 grams. For my propellant, I use screen-mixed powder. I have proven that the fineness of the charcoal is the factor that limits black powder power, and that 'super-milling' the charcoal component can make screen-mixed powder that rivals ball-milled black powder. Of course, for nozzleless rockets I use a hot charcoal, suitable for hot BP.

 

Your experimental propellant is a pretty complex mix, so who can predict how it will work? Personally, I would dampen it with 2 1/2% water, screen it again, and let it temper overnight to make sure the grains are soft enough, since you added VERY MUCH dextrin. I can't comment on your use of turpentine other than to say I would never do it. I would also never put a rocket motor in a dehydrator. I wouldn't use dextrin at all.

 

I have used 2% wax dissolved in naphtha to granulate nozzleless BP propellant, and, as NeighborJ says, the motors store for years.

 

I tape my sticks together at the bottom to give extra stability in flight and to prevent an accident if one of them snaps off at launch.

 

Hopefully something in these thoughts will be of value to you. Keep us informed!

Edited August 18, 2019 by justvisiting

[MinamotoKobayashi]

Hi Justvisiting, Your rocket/shell are awesome!

I have also made a lot of 6" shells powered by a r-candy granulated mix rocket.

But I haven't used any spindle to build them: I pressed directly the comp inside an aluminum tube and then I drilled a long hole with the help of a self-builded

tool like this:

 

 

It allow to make a perfectly centered and parallel hole inside the comp.

A ball bearing system allow a smooth rotation and avoid that the drill bit eat the hole iron walls.

 

This is a spectacular 6" shell powered by a granulated r-candy aluminum-case motor:

 

https://www.youtube.com/watch?v=RzQYk1mXo74

 

The weight was more or less the same of Your firework.

 

So, I preferred to use my last BP batch to prepared a new batch of coated rice hulls and I make another batch without dextrin and wax suitable for a rocket.

I used the traditional BP formula 75-15-10 plus 10% of KP, and I overmilled the mix for about 6 hours with enough alcohol into my ballmill.

Since the traditionals lead balls can contaminate the mix in a so long balmill time, I bought 100 brass balls of 1cm diameter each:

very expensive, but they cannot contaminate the powder, they are heavy enough and 100% sparks free.

And they cannot lose weight in the time.

Since I will use an aluminum tube, I cannot suffer tube relaxation in the time using water , so I decided to wet the powder with 2% of water and press it at 7500 PSI as You suggested.

Stay tuned

Edited August 20, 2019 by MinamotoKobayashi

[MinamotoKobayashi]

Guys, I read conflicting opinions about the use of water into the BP propellant.

One side say that the water increase the thrust, the other side tell the exact opposite. What is the truth?

And what is the correct percentage of water?

[dlking59]

Whatever you are doing it looks right/good to me. Very nice.

[NeighborJ]

As I've mentioned previously, you can't mix and match parts of different methods and expect the exact same results.

 

I suppose I should've said that my stored water pressed motors would inconsistently cato. That doesn't mean they were hotter after drying. The nozzle swells, the tube wall relaxes and things start to change.All my rockets use paper tubes, aluminum tubes should be expected to have very different performance characteristics of which I have no experience with. I would expect the clay nozzle to be effected by the moisture in the fuel but again your tubes can handle higher pressures. I consider a motor which can change its performance over time in storage to be unreliable even if it does its job, i want consistency and reliabile performace, water as a compaction aid does not do this for me.

 

You can't expect to find reliable advice for your process from anyone who has never used your materials. The advice I give is under the assumption that you are using standard building materials like the rest of us.

Edited August 21, 2019 by NeighborJ

[MinamotoKobayashi]

Hi Jason.

It is about 2 years that I do not use clay nozzle rockets anymore. For firework purposes nozzleless rockets are more suitables and never had CATOs because these kind of motor are more tolerant.

Besides this, my motors are always used the same month that they were built, so I will not have the drying issue because the storage time if short.

Finally, I will not have tube relaxation issue because I will use reusable aluminum tubes.

But if You tell me that is better to use wax anyway, I will use wax.

I can compensate the slightly loss of thrust adding further KP.

 

Now my goal is to lift a 8" shell.

For the 10" shells I could use in the next future multiple rockets, as I already done some times ago to lift a 8" shell with 3x r-candy rockets joined together with full success.

Edited August 21, 2019 by MinamotoKobayashi

[Zmuro]

If I would be pressing fuel into Al tube, I wouldn't use any water in fuel nor would I use dehydrator. You can use very hot BP fuel for nozzeless rockets and you have done that with a lot of milling and even adding KP to the fuel. I would use dry BP and added 1,5% of paraffin oil to the mix. You can do it without adding any solvent, just use atomized sprayer and screen it a few times to incorporate it well. The oil in the mix is just used to keep the dust down. That's just my 5 cents.

[justvisiting]

NeighborJ, I'm a little surprised that your water pressed motors were unreliable. I pressed only a couple in unwaxed tubes, and saw many slight compression lines on the tubes. When I pressed the same comp in waxed tubes, there were no lines. To me, no lines means no (or very little) relaxation.

 

I wonder about adding just KP to the BP propellant. My instinct would be to make granulated whistle and stir it into the propellant to increase the power, as Laduke does with his hybrid rockets. If using just KP, where is the fuel for it to act upon?

 

Sleeter's 'Amateur Rocket Motor Construction' book suggests putting a few wax shavings on top of the pressed nozzle to discourage absorption of moisture from the propellant. I didn't do it with mine, but the few I've made had no noticeable issues with the nozzle.

 

MinamotoKobayashi, I agree with NeighborJ that using an aluminum tube is so different than using the 'normal' cardboard tubes the rest of us use, that any advice we give might not apply.

 

These are a couple of tests I've done with screen-mixed propellant using 2.5% water as a compaction aid. I'm no good at adding images. These ones have to be clicked on to make them big enough to read the descriptions. Both rockets had the exact same amount of propellant pressed in, but one sat for 8 days before testing. The fresh one had a shorter burn time and more impulse. I'm not saying this proves that water is beneficial, but it indicates it doesn't hurt. If you get more propellant in the rocket with damp propellant than with dry (proven), that alone gives an advantage.

 

I wouldn't use water in an aluminum tube, as Zmuro mentioned. I wouldn't use a dehydrator for any rocket motor. Also, I wouldn't add whistle to a rocket made with an aluminum tube.

 

EDIT: I understood "KP" to mean potassium perchlorate. I didn't realize there was a propellant called KP.

 

 

Edited August 21, 2019 by justvisiting

[MinamotoKobayashi]

Well, I read some different opinions, the best way is to try all and then draw con conclusions

Sincerely, I have created near a hundred of rockets in aluminum tubes using r-candy mix with 1% RIO, 2% titanium and some demineralized water sprayed to allow more

compactation and never had issues.

Also, I putted these rockets in my dehydratator ad 70 °C for 3 hours and no issues again.

It is important to dry the water contained in the r-candy mix because more the comp is dried, more the thrust is increased.

Also, more the mix temperature is high, more the thrust is increased.

Probably sugar, KNO3, RIO and Titanium do not hurt the aluminum in presence of water, while the presence of sulfur in BP/KP could create unwanted reactions.

 

I have difficult to found paraffin oil, while I can found vasellin oil easily. I read the difference between the two oils, it is only a questions of carbon atoms numbers:

vasellina oil had 20+ carbon atoms chain while paraffin oil had at least 25 carbon atoms chain. Anyone can tell me if I can use vasellin oil in any case?

Edited August 21, 2019 by MinamotoKobayashi

[MinamotoKobayashi]

Justvisiting: yeah, often there is confusion about the "KP" term. I do not know why it is used to indicate also potassium perchlorate, that should be KCLO4.

KP is a variant of BP, where potassium nitrate is replaced with potassium perchlorate. The percentages are slightly different.

KP is usually used to enhance burst in smaller shells, such as a small percentage of granulated KP in a bag at the center of the shell or as a last coating in coated rice hulls.

Adding a small percentage of KP to the BP should enhance the thrust a lot.

For the momment I added 10 grams every 100 grams of propellant. If it work I will add 5 grams more of KP and I continue with 5 grams increment by time until the rocket CATO.

I fear that a 550 grams rocket in an aluminum tube will be a great CATO

[Zmuro]

Paraffin oil is used in production of vine, especially for keeping the vine from going bad. When vine is kept in large metal cistern you pour the paraffin oil on top of vine to prevent the oxygen spoiling the vine. 1L of paraffin oil cost 3€. It doesn't have any odor, taste or color. You can also use baby oil

[MinamotoKobayashi]

Ok, I found the real paraffin oil here:

 

https://www.ebay.it/itm/PARAFFINA-LIQUIDA-200-ml-PER-GELCOAT-NAUTICA-IMBARCAZIONI-SURF-GEL-COAT-BARCHE/301857274852?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D51207865ae54409f9981e4cb9007040c%26pid%3D100675%26rk%3D1%26rkt%3D15%26mehot%3Dlo%26sd%3D301857274852%26itm%3D301857274852%26pmt%3D0%26noa%3D1%26pg%3D2481888&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A8a49eda8-c510-11e9-9348-74dbd180b999%7Cparentrq%3Ababcff4216c0a688c2293fc0fff509a4%7Ciid%3A1

 

It is pricey, luckly I need only 2 grams for every 100 grams of propellant

 

 

Paraffin is different from vasellin, and commercially the two term are intend to be the same.

The baby oil is vasellin ...

[kaotch]

@mina.....

Since you are working on nozzleless BP rockets using an elaborate process of ballmilling with alcohol and dextrin etc in order to get acceptable granules? Why not using RED GUM instead of dextrin? This will create the same effect.

[dagabu]

It's always surprised me that people have got to either ball mill all the ingredients to powder or use alcohol and dextrin etc. For rockets, you DO NOT want the granules to be hard, you don't want paths for fire to travel, a simple mix of milled KNO3, sulfur and airfloat charcoal, mixed together in a ziplock bag and screened a few times with 1/2 a percentage of water finely misted over it will de-dust it an allow for a minimum of an airborne cloud of charcoal.

 

Spending money of mineral oil, paraffin, alcohol and dextrin etc is a huge waste.

[MinamotoKobayashi]

Hi Dagabu.

I reached my major goals following the directive of NeighborJ, that was the first users that followed me since the beginning with its precious suggestions

and also created which that I am now in the rocketry field.

In rocketry NeighborJ is a grandmaster, I trust in him.

Often I went out of the traditional path because I like to experiment, but the results was pretty nice.

Some delusions occurred, it is normal, but now I'm proud to have reached satisfaction in many of my projects.

 

I ballmilled BP and KP together in 100/15 percentage without dextrin in a alcohol syrup because this is the safest way to ballmill all the chems

together without any chance of explosions.

After dried I mixed the powder with 2 grams every 100 grams of the liquid mix 50/50 paraffin wax+turpentine.

I added again turpentine until the powder can be compacted like a ball, then I granulated it thru a 8 mesh screen and then dried.

This is the same identical procedure of the traditional BP granulation.

Now the very weak granules are ready to be packed at 7500 PSI for my new big rocket prototype with the aid of the great Zmuro custom tools.

Here is the result of the granulation:

 

 

The obtained granules are terribly reactive, much more than the granules obtained mixing the individually ballmilled components together.

And there is no residuals, the combustion is perfect.

If the rocket does not CATO, I think to have built a mini Space Shuttle

In the case of a CATO, I will lower the KP percentage until I will reach my goal.

Yes, the procedure is more pricey, one dollar for the alcohol and another 1.5 dollar for the turpentine.

But if You think that I spent 4 dollars only for the heavy sticks (to counterbalance the noticeable weight), surely this is not a

big problem for me, also because I will built a similar rocket every 30 days or so ..

Edited August 29, 2019 by MinamotoKobayashi

[dagabu]

I got to meet J at PGI this August, it was a true pleasure! What a nice guy, I only wish we had time to sit down and talk more.

[kaotch]

@minamotoK.

How did your experiment by adding Perc to BP worked out ? Did you already launched a rocket with this propellant?

[MinamotoKobayashi]

Yes I'm just preparing the thread, You can see it very soon!

[shockie]

I conversed with the late Ed Brown who worked at Estes Industries for over 30 years, where he designed and tested their BP engines.

 

Based upon his experience and several reports that I personally researched, more than 2% water results in

substantially slower burn rates.

This was typical fast 75/15/10

This BP was pressed to about 1.9 g/cm3

Edited November 26, 2020 by shockie