My New 1KG Nozzleless Hybrid Propellant Aluminum Tube Rocket

[MinamotoKobayashi]

Hello forum.

Since my next goal is to lift 8" and then 10" shells with a rocket, and I do not want to use dangerous mixes like whistle mix,

I created and perfectioned a new rocket with a new custom hybrid propellant mix.

I used a mix of BP and KP: 20 parts of KP for every 100 parts of BP.

Please remember that "KP" term is not the perchlorate acronym as often is mislabeled but the Shimizu burst charge formula:

 

70% Potassium perchlorate

18% Charcoal

12% Sulfur

02% Dextrin

Then, I added 2% of titanium sponge 400-1000 for a nice tail and finally 5% of phenolic resin.

Why phenolic resin?

Well, I suffered important fuel relaxation using BP with 2% paraffin wax into an aluminum tube.

Same soup increasing the wax percentage or using 1% water instead.

I tried to scratch the internal walls of the tube in many ways without appreciable results, so I switched to phenolic resin.

Why a so unusual choice?

First of all, I completely eliminate the unwanted fuel relexation issue!

Second, I can use pure ethyl alcohol without any kind of issues (alcohol do no react with the internal aluminum

walls and it is easy to dry).

Third, the resin with alcohol permit to pack the mix much more, creating a very hard matter, especially after dried.

Also, I used phenolic resin and not red gum because it burns faster.

All the chems was overmilled together for many hours into a ballmill soaked in ethyl alcohol for obiouvsly safety reasons, then dried

and granulated with a 20 mesh screen.

 

Dried mix:

 

Wetted mix (few grams of pure, water free ethyl alcohol, the same used to make spirits):

 

This is a brand new custom set built by the great toolmaker Zmuro together the big aluminum tube:

 

 

The first thing to do is to plenty wax the spindle to facilitate a lot the spindle extraction after the packing procedure.

I use a mix of 50% paraffin wax 50% turpentine as NeighborJ suggested me, the same mix that I will use for waxing

the internal walls of the cardboard tubes:

 

Inserting and centering the aluminum tube:

[/url]

 

Inserting the first part of the tube holder:

 

Inserting the second part of the tube holder:

 

Locking the tube holders:

 

The spindle is centered. Non perfectly centered, but acceptable:

 

Placing an handmade funnel over the top. I created this funnel cutting the upper part of a plastic bottle because it has a larger

aperture compared to the traditional kitchen funnels that permit me to spread better the mix inside the tube:

 

Starting to fill the tube with a spoon full of mix for every step:

 

The filling procedure, especially during the first steps, is a very delicate part because if the mix was not spreaded

homogeneously inside the tube, the spindle can run out of center. This happens especially when long spindles are used.

If this happen, the out-of-center spindle willl scrape against the hole of the second rammer when will be inserted, locking inside

the tube in a very bad manner, and in that case you will have to throw everything away! I have wasted some rockets and risked

to damage spindle and rammer before learning this important lesson!

So, the better way that I have found to avoid this is to look inside the tube if the spindle rest centered for every mix spoon.

If I note that the spindle goes out of center, the solution is very simple: I will tilt the tube in the direction where the spindle is at the

nearest point of the tube wall and put the next spoon of the mix maintaining the tube holder tilted: the mix will accumulate in that

direction, so the rammer will make more pressure to the powder between the spindle and the internal wall, forcing the spindle to

move to the opposite direction.

I will repeat this procedure for every mix spoon until the spindle is centered again:

 

Pressing the mix with a 10 tons hydraulic press. Repeating the pressing procedure for every mix spoon:

 

Since the pressure applied will vary for every rammer change, I must vary the tons applied to every rammer

to keep the 7500 PSI pressure needed.

Zmuro created for me a nice rocket pressure calculator.

The first rammer needs 4,4 tons:

 

The second rammer needs 4,8 tons:

 

The third rammer needs 5,2 tons:

 

The fourth rammer needs 5,9 tons:

 

Edited October 30, 2019 by MinamotoKobayashi

[MinamotoKobayashi]

It is important to respect the reference rings before changing the rammer:

 

Extracting the tube from the tube holder.

The tube was not deformed or shortened in any way:

 

Expose the base of the spindle:

 

Inserting the spindle extractor and extracting the spindle:

 

Thanks to the generous amount of paraffin wax + turpentine, the spindle went out easy:

 

The pseudo-nozzle and the conic hole:

 

The upper part with the delay:

 

Drying the rocket over my handmade dehydratator and added also a small fan just over the nozzle:

 

Adding a nice cap of hot glue to enhance the aerodynamicity:

 

Phew, it is a heavy rocket:

 

Wrapping the aluminum tube with gummed paper:

 

Gluing three long sticks for decent counterbalancing:

 

 

A slow green falling leaf Visco fuse joined to a superfast Visco fuse:

 

Inserting the fuse into the hole until the end and keep everything in place with some pressed cotton.

This also keep the humidity far away from the mix:

 

This was the first launch with only one stick:

https://www.youtube.com/watch?v=to4YDcBQazU&feature=youtu.be

 

The second launch with three sticks was much more stable:

https://www.youtube.com/watch?v=Iq2Qfo_HgbI&feature=youtu.be

 

That's all.

Unluckly the ending part of the aluminum tubes was completely melted and the sticks destroyed in many parts, so I cannot

reuse anything.

All the debris were found and rescued from the field to protect nature and environment.

Soon I will attach on the top a 8" shell (for a total of about 5KG firework!) to see if a right ignition altitude will be reached .. stay tuned!

Edited October 29, 2019 by MinamotoKobayashi

[justvisiting]

MinamotoKobayashi, I have been using a little trick to keep my spindles centered and it works very well. I make an insert out of rolled gummed tape or rubber tube, which goes up inside the first rammer. The length is important. The insert should fit snugly inside the rammer so it stays in place. After using the rammer, the insert usually stays put. Wiping it with contact cement might be good. The ID of the insert is sized so that the spindle tip is very slightly smaller, and slides in with little effort. The length is sized so that the tip of the spindle has entered the insert just as the bottom of the rammer contacts the nozzle/first increment. Then, when you press the first increment, the spindle goes up inside the insert and stays perfectly centered. I have used this method on all my long spindled rockets and it works perfectly.

 

Another suggestion I have made to toolmakers is to attach the tube support to the spindle base. This will prevent the (cardboard) tube from 'walking' down in the support, which makes the setup become wobbly. It will keep the spindle centered. Two rocket makers I know of have done this and they report good results.

[MinamotoKobayashi]

Hi.

Thanks for the first hint, I will try it!

About the second suggestion .. yes, I already noted that issue and fixed it in a similar manner:

 

 

This is a tool that I built some months ago for my drilled nozzleless granulated r-candy rockets.

As You can see, I can mount and lock the bottom plate with the recess using 4x screws, so the tube cannot slip anymore!

Edited October 30, 2019 by MinamotoKobayashi

[dynomike1]

So far i have only skimmed through this, i will read closer later. Is this a normal mix that you use? I get catoes with 75, 15, 10 when i put any weight on top.

[SharkWhisperer]

So far i have only skimmed through this, i will read closer later. Is this a normal mix that you use? I get catoes with 75, 15, 10 when i put any weight on top.

He details this in his Oct 29, 2019 post. Here's a partial excerpt....

 

" used a mix of BP and KP: 20 parts of KP for every 100 parts of BP.

Please remember that "KP" term is not the perchlorate acronym as often is mislabeled but the Shimizu burst charge formula:

 

70% Potassium perchlorate

18% Charcoal

12% Sulfur

02% Dextrin

Then, I added 2% of titanium sponge 400-1000 for a nice tail and finally 5% of phenolic resin."

Why bother querying formulas when you admit you've only yet just skimmed the thread that answers your question in detail??? At the very beginning of the very first post (of 3 total...). Feelin' a little lazy after the long weekend are we?