Casting KNSB with surfactant - what are your experiences?

[mabuse00]

Just did some experimentation with KNSB + surfactant.

 

I used a 27% solution of sodium laureth sulfate.

4 drops out of a one way use pipette per 50g batch where needed to properly cast KNSB fuel 65/35 around a rather slim spindled 15mm tool.

 

(Drop counting is a little vague, but I have no means to properly scale such small amounts.

8 drops are ~ 0,16g)

 

Using the surfactant really makes a huge difference, no more scooping, just pouring, perfect.

I'd say it's a succes.

 

 

The thing has one catch, it definitely slows down the fuel.

 

 

I got

 

3,8mm/s without surfactant
3,4mm/s with four drops/50g batch (+ ~0,16% surfactant)
2,8mm/s with eight drops/50g batch (+ ~0,32% surfactant)

KNO₃ came out of a kitchen blender, +1% brown iron oxide catalayst.

 

 

 

Have you guys ever tried to use surfactants? What are your eperiences?

[stix]

I did once try propylene glycol from some household product - shampoo I think. It did reduce the viscosity, but also soaped up - I think I used to much. I never did try it in an actual motor as it didn't burn very well. I tried to look for some pure propylene glycol or some other surfactant but never was able to find it, so I went in another direction.

 

I'd like to be able to try Sorbitol but it seems expensive and hard to get. I did have limited success with xylitol and erythritol. It was certainly easier to cast than sucrose, but expensive.

 

If your fuel burns slower, and you are doing core burners or bates grains, you could increase the length to bring the pressure and burn rate back up. You will need to experiment.

 

Cheers.

[stix]

Hey Mabuse, what was the outcome?

 

I've realised that to "cast small sugar rocket motors" is a hard task. If you are doing big ones (around 100mm+ diam) then it's fine because the retained heat will let you pour it, other than than that, there is no easy way. I've made devices in the past - ie. swinging a contraption around like a centrifuge to compact the sloppish fuel, but to no avail.

 

Ammonium perchlorate with a liquid plasticiser is always better. I went down that path years ago, unfortunately those chemicals are no longer available and that's why I love sugar motors. But It's like "pissing in the wind" in comparison.

 

That is the harsh reality with sugar rockets - there is no ultimate formulation - it is as it is. Good though as it is, I love sugar rockets, but it's important to understand the limitations.

 

Cheers.

Edited February 11, 2015 by stix

[mabuse00]

Well, not much progress so far...

 

Thank you for mentioning propylene glycol.

Thing is, according to this report here

http://www.thefintels.com/aer/propyleneglycol.htm

it only works for normal KNSU, not with sorbitol. In my experience KNSB is very much superior to cast and safer to work with, so I am very reluctant to swap to KNSU.

 

 

I ultimately want something like Pirotex presented, but I'd want a little more power. Just for shooting pyrotechnics. I'm not clear about the hole thing, maybe it's a fruitless endeavour, I'll see.

 

My 15mm rockets work fine with it. And I've also made a 1lb BP spindled motor with it, ready for testing. The core looks fine.

 

A problem I encountered with the 15mm motors was the slow runup, resulting very curved flightpath, though ignition was (at least allmost) on top of the core. When the motor reached full power the rocket had already gone a little sideways...

 

For the next test with the 1lb motor I prepared a massive blob of perchlorate hotprime for quick ignition.

 

 

 

you could increase the length to bring the pressure and burn rate back up

For optimal performance I special tool would obviously needed - long and slim. Normally I'd say this is hard to realise. With surfactant and maybe preheated spindle it might very well work.

 

I got the idea when i saw seeing Pirotex' videos. Bearing in mind that

-his where even nozzlelesss (I'd prefer that too - less pressure, less problems with all components)

-the core stated in his videos is even shorter than a standard BP tool

one can easily see that this has potential.

 

As it is, not very impressive, little payloads for massive rockets, but with a longer core - who knows...

[stix]

Well, not much progress so far...

 

Thank you for mentioning propylene glycol.

Thing is, according to this report here

http://www.thefintels.com/aer/propyleneglycol.htm

it only works for normal KNSU, not with sorbitol. In my experience KNSB is very much superior to cast and safer to work with, so I am very reluctant to swap to KNSU.

 

 

I ultimately want something like Pirotex presented, but I'd want a little more power. Just for shooting pyrotechnics. I'm not clear about the hole thing, maybe it's a fruitless endeavour, I'll see.

 

My 15mm rockets work fine with it. And I've also made a 1lb BP spindled motor with it, ready for testing. The core looks fine.

 

A problem I encountered with the 15mm motors was the slow runup, resulting very curved flightpath, though ignition was (at least allmost) on top of the core. When the motor reached full power the rocket had already gone a little sideways...

 

For the next test with the 1lb motor I prepared a massive blob of perchlorate hotprime for quick ignition.

 

 

For optimal performance I special tool would obviously needed - long and slim. Normally I'd say this is hard to realise. With surfactant and maybe preheated spindle it might very well work.

 

I got the idea when i saw seeing Pirotex' videos. Bearing in mind that

-his where even nozzlelesss (I'd prefer that too - less pressure, less problems with all components)

-the core stated in his videos is even shorter than a standard BP tool

one can easily see that this has potential.

 

As it is, not very impressive, little payloads for massive rockets, but with a longer core - who knows...

 

Oh, that's a shame about the propylene glycol not working for Sorbitol. I agree that sticking with Sorbitol is probably a wise thing. The melt point of 95C compared to 186C is safer I believe. Sorbitol is over $50US per kilo where I live, so I've never had the luxury of being able to test with it.

 

I think the reason it's expensive it to dissuade the druggo's not to use it to cut their drugs - similar to some of the other sugars I would like to have tried like mannitol etc. I've settled on using dextrose(glucose) powder which melts around 140C but is still workable at 120.

 

I take it that you are using a nozzle. What are your specs, ie. nozzle diam, fuel length, fuel weight, casing material etc.? You certainly don't want a slow take off, especially when carrying a payload. I'm not sure about brown iron oxide, but I've used red iron oxide in small nozzlesless rockets and they take off in a flash!

 

I've never had to use a modifier to increase the burn-rate of the fuel in my nozzled bates grains configurations - in fact, on the contrary - you actually want the fuel to burn slower, that way you get a longer burn time. If you need more thrust, lengthen the fuel, which is easier to do that mucking around with nozzle sizes.

 

I don't like the "short & fat" variety particularly for nozzled motors because the difference between the starting and ending point (Kn Ratio's) is far too wide, and you end up wasting fuel at take off, and have too much pressure at the end. Instead, my standard 1lb motor is taller, shaped something like the space shuttle boosters. I light mine electronically with the igniter inserted into the core as far up as possible - this insures an even ignition and no fuel waste.

 

I'm interested in what you are doing because that's exactly what I want to achieve. That is, to use my sugar rockets to lift a shell or can, when I get to that level of star making.

 

I've attached a graph of my standard motor test - you may get some ideas from my specs. and I'm sure you could give me some good pointers too. You can see from the graph that at approx. .2 secs into the burn it's producing almost 1kg of thrust - which should easily be able to lift a 100g or so shell.

 

Cheers.

[Mumbles]

I wonder if something similar to propylene glycol would work. Something like ethylene glycol or glycerine. Glycerine is known to dissolve sorbitol to some degree. It's also commonly used in cake decorating in frosting to prevent the sugar from crystallizing.

[yelloj]

I have extensive experience on the use of surfactants to improve the pourability of sugar propellants. Sodium or ammonium laureth (not lauryl, only laureth) sulfate is the best surfactant to use that can be easily obtained. Several other surfactants work even better but are much harder to obtain (see my web site: http://www.ajolleyplace.com/surfactant.html). These surfactants work best when the oxidizer is finely ground. They also work best when the sugar is a sugar alcohol such as sorbitol. A KNO3/sorbitol (65:35)w mixture is quite fluid and can be poured without the use of surfactant if one uses granular KNO3 as one gets when purchased. If you grind the oxidizer to get better performance then the viscosity of the molten propellant becomes too high to pour. The use of a surfactant does often slow the burn rate of the propellant. I overcome this by using a small amount (0.25% or so) of RIO. The burn rate of the propellant reverts back to the normal burn rate of the propellant without the use of surfactant. You now have the best of both worlds.

 

Having said this I have been using a different approach to pourable propellants over the past couple of years. Several oxidizer mixtures (i.e. KNO3/NaNO3, KNO3/Ca(NO3)2, and NaNO3/Mg(NO3)2) have melting points, when combined with sugars, between 130 and 180C. Propellant made from these ingredients is also very pourable. One of my favorites, 35% KNO3/ 30% NaNO3/ 35% mannitol, is so runny when molten that it can easily be poured into 18mm casting tubes with coring rod in place.

[yelloj]

The link above should read ...ajolleyplace.com/surfactant...

 

http://www.ajolleyplace.com/surfactant.html

[stix]

I have extensive experience on the use of surfactants to improve the pourability of sugar propellants. Sodium or ammonium laureth (not lauryl, only laureth) sulfate is the best surfactant to use that can be easily obtained. Several other surfactants work even better but are much harder to obtain (see my web site: http://www.ajolleyplace.com/surfactant.html). These surfactants work best when the oxidizer is finely ground. They also work best when the sugar is a sugar alcohol such as sorbitol. A KNO3/sorbitol (65:35)w mixture is quite fluid and can be poured without the use of surfactant if one uses granular KNO3 as one gets when purchased. If you grind the oxidizer to get better performance then the viscosity of the molten propellant becomes too high to pour. The use of a surfactant does often slow the burn rate of the propellant. I overcome this by using a small amount (0.25% or so) of RIO. The burn rate of the propellant reverts back to the normal burn rate of the propellant without the use of surfactant. You now have the best of both worlds.

 

Having said this I have been using a different approach to pourable propellants over the past couple of years. Several oxidizer mixtures (i.e. KNO3/NaNO3, KNO3/Ca(NO3)2, and NaNO3/Mg(NO3)2) have melting points, when combined with sugars, between 130 and 180C. Propellant made from these ingredients is also very pourable. One of my favorites, 35% KNO3/ 30% NaNO3/ 35% mannitol, is so runny when molten that it can easily be poured into 18mm casting tubes with coring rod in place.

 

Interesting, and thanks for the info yello. It's very timely because I've got some Sorbitol at a reasonable price which has been hard to come by. I grind my KNO3 very fine and therefore it's not "pourable" but I use it as a "plasticine" type product that can be moulded and pressed.

 

 

One of my favorites, 35% KNO3/ 30% NaNO3/ 35% mannitol, is so runny when molten that it can easily be poured into 18mm casting tubes with coring rod in place.

 

 

Well, that sounds like the "Holy Grail" in sugar rockets. A pourable "sugar fuel" that sets up easily - good work. With the addition of the NaNO3, does that mean it's more hygroscopic?. I checked out the usability of mannitol a while back and the problem for me is that mannitol is so way way way expensive because people use it to cut illicit drugs.

 

Very late here now, so i will re-read tomorrow what you posted.

 

Cheers.

[yelloj]

Yes. I wish mannitol were less expensive but it sure is, without a doubt, the best sugar alcohol out there. It is exceptionally non-hygroscopic - by far the best one as far as water pick-up goes. It has fewer issues with burn rate/pressure spikes and does not suffer with ignition difficulties like erythretol does. Another sugar alcohol I like is Isomaltitol. It is also quite expensive but no where as bad as mannitol. It has a much faster burn rate.

[bmcpeak363]

Well, not much progress so far...

 

Thank you for mentioning propylene glycol.

Thing is, according to this report here

http://www.thefintels.com/aer/propyleneglycol.htm

it only works for normal KNSU, not with sorbitol. In my experience KNSB is very much superior to cast and safer to work with, so I am very reluctant to swap to KNSU.

 

 

I ultimately want something like Pirotex presented, but I'd want a little more power. Just for shooting pyrotechnics. I'm not clear about the hole thing, maybe it's a fruitless endeavour, I'll see.

 

My 15mm rockets work fine with it. And I've also made a 1lb BP spindled motor with it, ready for testing. The core looks fine.

 

A problem I encountered with the 15mm motors was the slow runup, resulting very curved flightpath, though ignition was (at least allmost) on top of the core. When the motor reached full power the rocket had already gone a little sideways...

 

For the next test with the 1lb motor I prepared a massive blob of perchlorate hotprime for quick ignition.

 

 

For optimal performance I special tool would obviously needed - long and slim. Normally I'd say this is hard to realise. With surfactant and maybe preheated spindle it might very well work.

 

I got the idea when i saw seeing Pirotex' videos. Bearing in mind that

-his where even nozzlelesss (I'd prefer that too - less pressure, less problems with all components)

-the core stated in his videos is even shorter than a standard BP tool

one can easily see that this has potential.

 

As it is, not very impressive, little payloads for massive rockets, but with a longer core - who knows...

Hello All,

Does anyone know if the Fintels rocketry site is still active? I seems to be offline.

Thanks.

[stix]

It doesn't appear to be active to me either. It's been years since I've looked at the site so I've no idea if it's temporary or final.

 

I can't remember exactly what info was provided but I'm sure I browsed it - ummm... just realised I was the one who posted that link almost 2yrs back.

 

That's a shame, I should have taken screen shots. Hopefully that info is not lost and it's been repeated somewhere else.

[Mumbles]

The parent page (www.thefintels.com) is active, but the rocketry portion seems to not be. Hopefully it is temporary, but there is always archive.org

[bmcpeak363]

I wonder if something similar to propylene glycol would work. Something like ethylene glycol or glycerine. Glycerine is known to dissolve sorbitol to some degree. It's also commonly used in cake decorating in frosting to prevent the sugar from crystallizing.

I ordered some food grade propylene glycol and tried it over the weekend. I made 2- 500 gram batches. I am using 65%, KN, 17% powdered sugar, 16.75% Karo syrup for flexibility and .25% Iron Oxide. I prepared it 2 different ways, dry ingredients mixed for 3 hours in a tumbler and melted at 225 degrees, and blended with 1/3 cup water and cooked until water has evaporated at 325 degrees. I added 2% propylene glycol to both, it did help the viscosity some but it was not pourable, but easier to work with. My KN is fairly fine ground, could this be the problem? When I added the propylene glycol it smoked a good bit, I wonder if most of it evaporated? As always the blended with water mix is more energetic when I do test strands. Has anyone had similar results?

I am going to try the 35% KNO3/ 30% NaNO3/ 35% Mannitol and see how that goes.

[bmcpeak363]

I have extensive experience on the use of surfactants to improve the pourability of sugar propellants. Sodium or ammonium laureth (not lauryl, only laureth) sulfate is the best surfactant to use that can be easily obtained. Several other surfactants work even better but are much harder to obtain (see my web site: http://www.ajolleyplace.com/surfactant.html). These surfactants work best when the oxidizer is finely ground. They also work best when the sugar is a sugar alcohol such as sorbitol. A KNO3/sorbitol (65:35)w mixture is quite fluid and can be poured without the use of surfactant if one uses granular KNO3 as one gets when purchased. If you grind the oxidizer to get better performance then the viscosity of the molten propellant becomes too high to pour. The use of a surfactant does often slow the burn rate of the propellant. I overcome this by using a small amount (0.25% or so) of RIO. The burn rate of the propellant reverts back to the normal burn rate of the propellant without the use of surfactant. You now have the best of both worlds.

 

Having said this I have been using a different approach to pourable propellants over the past couple of years. Several oxidizer mixtures (i.e. KNO3/NaNO3, KNO3/Ca(NO3)2, and NaNO3/Mg(NO3)2) have melting points, when combined with sugars, between 130 and 180C. Propellant made from these ingredients is also very pourable. One of my favorites, 35% KNO3/ 30% NaNO3/ 35% mannitol, is so runny when molten that it can easily be poured into 18mm casting tubes with coring rod in place.

"can be poured without the use of surfactant if one uses granular KNO3 as one gets when purchased".

Does this mean Prilled? Thanks.

[bmcpeak363]

I have seen mentioned the Acme Rocket Motor Test Stand. Does anyone know if this is still available?

Thanks.

[NeighborJ]

ACME test stands are not in production currently. However they are made by Pete Hand with an outdated windows software which does not operate on newer windows versions. If he gets enough orders he does make limited quantitys of stands and can be contacted thru Fireworking.com. Id love to have one also but was strapped for cash the last time he was making them. They run around $400usd. Every so often someone sells used ones, which is likely your best bet provided you have an outdated oprating system on an old computer. Edited January 2, 2017 by NeighborJ

[Mumbles]

Pete is a member here as well under the name Peret.

 

Admittedly, I haven't tried using Windows 8 or 10, but the software works fine in windows 7. Have you tried opening the program in compatibility mode, if the newer versions even have it. I'm resisting upgrading if at all possible.

[OldMarine]

Someone on FW is working on getting the ACME set up to run Win 10.

[stix]

"can be poured without the use of surfactant if one uses granular KNO3 as one gets when purchased".

Does this mean Prilled? Thanks.

 

I think prills would be around the size of a grain of rice? At that size I don't think the fuel would burn very well.

 

One thing I do know is that the finer you go with the KNO3, the harder it is to pour. My KNO3 is something like castor sugar (a bit finer than white table sugar). I did a test once using Xylitol and it was reasonably pourable. I did the same with finely milled (confectioners sugar) and it turned into a thick paste, no way pourable.

 

These days I've gone off the idea of a 'pourable' fuel and instead make a 'putty' and press it instead. Using Sorbitol gives you a much longer setup time - ie. longer before it sets and goes hard.

[mabuse00]

I haven't done any further testing since then..

 

My last tests in 1lb motors never did produce any thrust. I had no time to reveal what was the problem, maybe it wasn't the sodium laureth sulfate but something else...

[bmcpeak363]

I would like to ask the opinion of those who have been making their own HP rocketry sugar propellant for awhile. I have test fired and had 2 successful launches without anything exploding. My question is that i am considering buying the data acquisition package that includes the load cell from Aerocon. I would build a test stand for it.

I am hesitant to spend the money on that. Would rather buy chemicals and rockets.

Do you think it is needed to proceed safely?

[stix]

No, I don't think you need one to proceed safely.

 

A test stand and software is useful for checking the consistency of your motors. With the measured data you can also do calculations to predict altitude.

[yelloj]

"can be poured without the use of surfactant if one uses granular KNO3 as one gets when purchased".

Does this mean Prilled? Thanks.

When I purchase KNO3 I buy it in 50 lb bags from hydroponics type fertilizer supply houses. This KNO3 always comes as a fine crystalline material much like table salt.

[yelloj]

No, I don't think you need one to proceed safely.

 

A test stand and software is useful for checking the consistency of your motors. With the measured data you can also do calculations to predict altitude.

 

I would like to ask the opinion of those who have been making their own HP rocketry sugar propellant for awhile. I have test fired and had 2 successful launches without anything exploding. My question is that i am considering buying the data acquisition package that includes the load cell from Aerocon. I would build a test stand for it.

I am hesitant to spend the money on that. Would rather buy chemicals and rockets.

Do you think it is needed to proceed safely?

If you are using KNO3/sorbitol motors you really do not need to do a lot of testing via a test stand. This propellant is really quite well characterized. If you size your nozzles to deliver a Kn of ~ 300 - 350 you will have no problems. If you want to experiment a bit with other sugars or additives then you will want to use a test stand to characterize your propellants.