4" And 6" Shells With Dragon Eggs

[MinamotoKobayashi]

First launch:

4" Shell With Dragon Eggs.

Cardboard rocket 150mm lenght, 25mm inside diameter.

Propellant used: granulated r-candy mix plus 2% 400-1000 titanium sponge.

Packing pressure: 7000 PSI.

Rocket type: nozzleless.

Hole diameter: 10mm.

Hole lenght: 115mm.

Patience to insert all the micro stars: A LOT !!!

https://youtu.be/pPfN9_S8tgk

Second launch:

6" Shell With Golden Glitters Dragon Eggs Core.

New aluminum body rocket 400mm lenght, 27mm inside diameter.

Propellant used: granulated r-candy mix plus 2% 400-1000 titanium sponge.

Packing pressure: 7000 PSI.

Rocket type: nozzleless.

Hole diameter: 12mm.

Hole lenght: 300mm.

https://youtu.be/SMQvLMgIBko

Edited October 26, 2019 by MinamotoKobayashi

[pyrogenius007]

Nice

[Aspirina]

What going on the second rocket? it sems like the crackeling stars dont burn like expected? anyway nice rockets!

[MinamotoKobayashi]

Yes I experimented issues, but only if the dragon eggs are used as a core for other effects. The primed dragon eggs alone works great, so since now I will prepare two different kinds of stars inside a shell to obtain both the effect and a good crackling (timed by the prime thickness).

[justvisiting]

Yes, very nice. What is the thickness of the aluminum wall on the second rocket motor?

[MinamotoKobayashi]

Hi. The thickness is 1.5mm, that is perfect for that use.

It is also reusable many times!

[Aspirina]

How do you solve the problem of crackeling cores?

[MinamotoKobayashi]

When I prepare dragon eggs, I will use it alone, together the other stars. I will not use Dragon Eggs as cores anymore ...

Edited October 30, 2019 by MinamotoKobayashi

[ExplosiveCoek]

What type of rocket stick do you use for the 6'' header rocket? Mine tend to spiral a lot during take off and bend over too quickly. I'm thinking I need to increase their power

[justvisiting]

I'm not the maker of those excellent shells and rockets, but I put 6" shells on rockets too. For some time now, I've used two sticks, taped together on the bottom third or so, so they look like a crutch. The flights are always true, with no deviations to date. For a 3lb rocket lifting a 6" shell, I use sticks 5-5 1/2' long, 3/8-7/16" on a side. The rocket is launched from a tube. The tube doesn't need to be long enough to reach the motor if the rocket has enough power. Only the sticks need to be inside the tube.

[MinamotoKobayashi]

For large shells the spiral effect is common if You do not use enough counterbalance weight.

Also, two sticks are recommended for 6"+ shells to avoid unwanted issues like spiral effect of not linear trajectory.

Here is my complete tutorial how to lift perfectly using an aluminum tube and my granulated r-candy mix:

 

https://www.amateurpyro.com/forums/topic/13292-making-a-granulated-r-candy-powered-aluminum-rocket-tube-for-6-shells/

[RubberRed1999]

Very nice. Well done!

[ExplosiveCoek]

Very detailed tutorial, thanks. Not sure how I missed that one.

 

So how do you know how much counterbalance you need to add?

 

I used 2 rectangle shaped sticks seperately, and another time I taped them togeter.

Shape was then almost 20 x 20 mm and roughly 1 meter long.

 

For measuring the balance, I've put my finger as the balance point, and it was roughly halfway the whistle motor. Normally it should be OK if the balance is below the shell heading.

[MinamotoKobayashi]

Yes You are right, more the baricentre is far from the shell, better will be the trajectory.

It is not needed to have the baricentre at the center of the rocket: some cm after the shell is more than enough.

Usually I use 2x1250mm rectangle shaped samba sticks for my 6" shells, glued with hot clue and forther locked with some turns of gummed tape.

[ExplosiveCoek]

And what dimensions are the rectangles?

 

I'm just trying to get a better feeling why my rockets are still spiralling since technically everythings seems to be done correctly and the central point of gravity is close to or below the rocket engine and for sure below the shell.

[NeighborJ]

Assuming your rocket is sticked and balanced properly then other causes are misaligned sticks or spindle cocked off center when pressing. The latter is quite common and the builder is often unaware of the issue.

[ExplosiveCoek]

Thanks for the input! I try to prevent that by using exactly a 90 degree angle cutter, and my tooling is made from stainless.. So not the most flexible material around. I've never seen my cores to not be straight. I could spin the rocket on the spindle without a single wobble in there.

 

Sticks are roughly 180 degrees opposite of eachother, but might not exactly be like that.

[justvisiting]

ExplosiveCoek, it sounds like you are using a 3lb whistle motor to lift a 6" shell, with sticks one meter long? Is this right? If so, I would use longer sticks, taped together at the bottom. Whistle motors have more tendency to spiral than other motors, I found.

[NeighborJ]

Thats a good point JV, anything that isn't top lit is subject to one side of the core igniting a split second before the other side. On motors which only burn for.3-1second you can see how the resulting irregular shaped core can cause a bit of side jetting. I've noticed this to be a large issue on shorter cores of all motor types.

 

One last scenario happens on endburners, often poorly made nozzles are subject to irregular nozzle erosion. This can cause side jetting as well but it also loses most of its thrust.

Edited November 13, 2019 by NeighborJ

[ExplosiveCoek]

ExplosiveCoek, it sounds like you are using a 3lb whistle motor to lift a 6" shell, with sticks one meter long? Is this right? If so, I would use longer sticks, taped together at the bottom. Whistle motors have more tendency to spiral than other motors, I found.

 

I'm not sure about the lb's, it's ID is 22 mm though. I had passfire to convert it, but abo is gone now. It's indeed a whistle motor. I'll check for the QM ignition too. I'm just using some visco now at the bottom as I didn't experience anything like this with smaller rockets. 5 " headers also fly nice with only one of those sticks and a shorter core, but same dia motor.

[dangerousamateur]

@MinamotoKobayashi:

 

Great work!

 

What I do not understand is how you got your R-Candy fast enough to work even nozzleless.

Especially the 150mm short engine.

I find that one needs really good BP for those, and really good BP is MUCH faster than R-Candy.

 

My sorbitol rockets in the past where nozzled, and they barely left the ground...

[MinamotoKobayashi]

Explosivecoek: the dimensions of the sticks are 1cm x 1,5cm x 125cm lenght.

 

The ways to push the r-candy rockets at the best are:

 

1. Use the classical 65/35 formula and add 1% RIO; add also 2% of 450-1000 Titanium for a nice fluffy tail.

I didn't noticed appreciable loss of thrust adding so few Titanium.

2. Found the right RIO. There are tons of different RIOs! I was lucky to found the best RIO available in the oldest grocery store of my city;

3. Granulate the propellant following my own tutorial;

4. Slightly wet the propellant: I use the classical mix 70% distilled water 30% ethyl alcohol;

5. Press the granulated propellant at 7000+ PSI (for aluminum tubes). For cardboard tubes there is the risk to deform the shape and shorten the overall lenght of the rocket, also if the walls were waxed, so it is better to lower the pressure applied (it is the classical try-and error method);

6. Dry well the rocket in a dehydratator at 70 °C for 1 hour. Redrill the hole (wetted mix should be present inside the hole). Dry again the rocket for another hour.

Do not use ventilated electric oven because the dangerous radiant heat. If You have only ventilated electric oven insulate the rocket putting aluminum foils

between the heating elements and the rocket. The foils must never touch the heating elements or the rocket body.

 

Finally, the lenght and the diameter of the hole play the most important part. Usually I push my rockets to the very limit, but if everything is made following my original specs,

the CATOs are rare. I love nozzleless rockets because they are much more tolerant compared to the nozzled ones, and create a tremendous thrust for few seconds,

that is ideal for fireworks.

Edited November 18, 2019 by MinamotoKobayashi

[dangerousamateur]

I can only assume that dissolving and recristalisation of the sugar makes a difference.

Personally I dont like the method, because of the dangerous cooking.

Especially with sucrose instead of sorbitol.

 

Do you ballmill sugar and nitrate together?

[MinamotoKobayashi]

The procedure that I use is not dangerous because all the chems are dissolved and boiled in water.

For this method is not necessary to ballmill the chems.

Here is my complete tutorial:

 

https://www.amateurpyro.com/forums/topic/13028-how-to-make-hot-granulated-r-candy-mix/