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4" And 6" Shells With Dragon Eggs


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#1 MinamotoKobayashi

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Posted 25 October 2019 - 08:28 PM

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 !!!
 
48960726917_0cd855353c_b.jpg
 
48960730727_a8f14eeaa9_b.jpg
 
 
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.
 

Edited by MinamotoKobayashi, 25 October 2019 - 08:29 PM.

  • Zmuro, pyrokid, fckiamdead and 5 others like this

#2 pyrogenius007

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Posted 26 October 2019 - 02:17 AM

Nice



#3 Aspirina

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Posted 27 October 2019 - 12:33 PM

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


«The first great virtue of man was doubt, and the first great defect was faith» Carl Sagan

 

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#4 MinamotoKobayashi

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Posted 27 October 2019 - 06:32 PM

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).



#5 justvisiting

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Posted 27 October 2019 - 11:53 PM

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



#6 MinamotoKobayashi

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Posted 28 October 2019 - 10:16 AM

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

It is also reusable many times!



#7 Aspirina

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Posted 30 October 2019 - 01:50 PM

How do you solve the problem of crackeling cores?


«The first great virtue of man was doubt, and the first great defect was faith» Carl Sagan

 

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#8 MinamotoKobayashi

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Posted 30 October 2019 - 02:23 PM

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


Edited by MinamotoKobayashi, 30 October 2019 - 02:23 PM.


#9 ExplosiveCoek

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Posted 01 November 2019 - 03:36 PM

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



#10 justvisiting

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Posted 01 November 2019 - 05:34 PM

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.



#11 MinamotoKobayashi

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Posted 01 November 2019 - 07:02 PM

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.amateurp...e-for-6-shells/



#12 RubberRed1999

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Posted 06 November 2019 - 07:07 AM

Very nice. Well done!

#13 ExplosiveCoek

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Posted 08 November 2019 - 12:54 PM

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.



#14 MinamotoKobayashi

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Posted 09 November 2019 - 07:59 PM

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.



#15 ExplosiveCoek

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Posted 11 November 2019 - 02:33 PM

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.



#16 NeighborJ

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Posted 11 November 2019 - 05:20 PM

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.

#17 ExplosiveCoek

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Posted 12 November 2019 - 04:31 PM

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.



#18 justvisiting

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Posted 12 November 2019 - 05:06 PM

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.



#19 NeighborJ

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Posted 12 November 2019 - 06:13 PM

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 by NeighborJ, 12 November 2019 - 06:18 PM.


#20 ExplosiveCoek

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Posted 13 November 2019 - 03:32 PM

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.






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