Crumbling Nozzleless Rocket "Nozzles" (any tricks?)

[scrmlw]

Hi, Thanks so much for having me!

I've been Testing different whistle rockets.

I make my own spindles.

For an exclusively nozzleless rocket, I'll use a °33 divergent section.

On my latest spindle, I keep getting crumbly "nozzles".

 

Any tricks to getting your whistle rocket off the spindle without bungering up this critical, yet delicate part?

I've flown a few, and CATO'd a few.

Kind of running right up against the redline already, I'd sure like to take this variable out of the equation.

[davidh]

Your spindle may not be completely round and true. Twist as little as possible when removing the motor from the spindle, and do not grip near the bottom of the motor. You may also be using too large an increment.

[justvisiting]

I have occasionally run into that problem as well, with tooling that never did it before. Others have reported it too, at the same time I had the issue. It seems to happen in the winter when the air is dry. I don't think it's moisture levels in the propellant, but maybe the elasticity of the tube could be an issue? Anyhow, a simple workaround was to press a little BP as at least part of your first increment, or a mix of BP and whistle, 50/50.

[dangerousamateur]

I found that waxing the spindle helps.

The crumbling nozzle does not hurt a nozzleless motor anyway, it just an flaw for the eye

[justvisiting]

I wax the spindle mostly now too. And the tube. And the propellant (sometimes)

[scrmlw]

Your spindle may not be completely round and true. Twist as little as possible when removing the motor from the spindle, and do not grip near the bottom of the motor. You may also be using too large an increment.

I had wondered if there was a trick to not twisting it, or only twisting in 1 direction. Didn't think of not gripping the bottom.

 

I have occasionally run into that problem as well, with tooling that never did it before. Others have reported it too, at the same time I had the issue. It seems to happen in the winter when the air is dry. I don't think it's moisture levels in the propellant, but maybe the elasticity of the tube could be an issue? Anyhow, a simple workaround was to press a little BP as at least part of your first increment, or a mix of BP and whistle, 50/50.

I'll give that a try. Been having bad luck with my BP rockets lately...

 

I found that waxing the spindle helps. The crumbling nozzle does not hurt a nozzleless motor anyway, it just an flaw for the eye

I'll try that. Been meaning to bring some wax to the pressing station.

The crumbling nozzle doesn't hurt? I had figured it might burn unevenly, leading to pathways for the fire, or being the equivalent of a cracked grain.

I usually smooth it out with my finger, but then it's still disturbed and not smooth and shiny / compressed.

I've had mixed success, but then again, I have that with most of my rockets

That'd be a load off to know for sure.

 

I wax the spindle mostly now too. And the tube. And the propellant (sometimes)

Sometimes even the tried and true waxed / phlegmatized propellant sticks and crumbles a little, but lately I've been experimenting with "Military whistle", replacing redgum with phenolic resin, and just pressing it dry.

Will try waxing the spindle next time.

 

Thanks All for all the replies!!

 

[cmjlab]

If you crack the code on the "military whistle" please share your lessons. I tried that formulation in the past and had the same issue in that it didn't consolidate well enough th not crumble when removing the spindle (I use Caleb's H/U and Whistle Spindles and still had the issue). It also sure felt less waxy / compressed when pressing increments than the typical Potassium Benzoate whistle that resembles a glass like surface when I'm finished pressing the whistle rocket.

 

Charles

[scrmlw]

If you crack the code on the "military whistle" please share your lessons. I tried that formulation in the past and had the same issue in that it didn't consolidate well enough th not crumble when removing the spindle (I use Caleb's H/U and Whistle Spindles and still had the issue). It also sure felt less waxy / compressed when pressing increments than the typical Potassium Benzoate whistle that resembles a glass like surface when I'm finished pressing the whistle rocket.

 

Charles

Will do. I'll either start a new thread or post in one of the previous ones I've been scouring. I've been using KBenz and Phenolic instead of Sali and RedGum.

The spindles I turn are pretty close to a H/U and Whistle spindle. Been experimenting with a fatter base diameter though.

Had good luck with 67-29-1-3 but I'm testing to see if I really need the Catalyst in there.