Balancing Rocket Sticks - Necessary?

[dagabu]

There is a huge amount of information related to rockets and CG, some have taken this information and applied it to pyrotechnical rockets as well and you see the results at club meets and convention...

 

As far as a "formula" goes, you just need to keep cutting until your rockets no longer track well IN WIND then add some back to get stable flights. Sadly, almost nobody has done this formally and recorded it and collected the data.

 

 

Dave,

Can you clarify how you ARE determining the stick length?

I don't have a lot of experience with rockets, but of the rockets I have launched (B.P. and Whistle all 3/4" ID) Ive never balanced anything. I just used two sticks approximately 20" long (~3/8" x 1/4") and they launch relatively straight.

So I'm curious if it's a certain # relative to tube length, if there is some formula, or if it's just based on experience to determine what length sticks will work best?

Thanks. I apologize if you answered my question in your post and I just didn't understand).

Charles

*Edit* I haven't tried any headers on them either, so I'm not sure what effect that would have on length either.

[nordicwolf]

_{David, what size rockets were you describing a few posts above? Please clarify the tube length, tube diameter, and what sort of tooling used.}

 

_{The description said "sali-boosted strobe" but I cannot envision what that tooling might look like. Whistle? Hybrid/Universal? strobe (whatever that means...I refer to that rocketsketchertool for a picture)}

 

_{Thank you.}

[dagabu]

1#, 7.5", 1" OD, SLD Universal Hybrid

 

[Rustoleum]

David,

 

Is the drawing correct that the tube is drilled for the Visco fuse?

Any advantage other than less chance of Visco falling out before ignition?

 

Thanks.

[cmjlab]

Im sure Dave will get back to you, but it's fused that way to hold the fuse securely, have the fuse barely touch the whistle grain guaranteeing ignition but not blocking or obstructing the core potentially causing overpressurization and CATO.

 

Charles

[dagabu]

Sorry, I have been on vacation...

 

This is Ned Gorski's drawing but yes, I do drill my tubes instead of do the loop in the butt. I drill below the fuel grain, the side-spit from chinese fuse lights 'em every time.

[Dipsomaniac]

Yes. Balancing the Engine on stick one of the most important parts

[dagabu]

Yes. Balancing the Engine on stick one of the most important parts

 

Actually, its largely irrelevant since the CG moves forward in 100ths of a second, sending the balance forward before before the torque on the stick is fully passed. You would be better served with 2 sticks to counter the torque for a straighter flight.

[nordicwolf]

I read somewhere that using a stick about 6x the length of the motor is a good place to start. For 3/4"x7.5" that would be a 45" stick. @dagabu posted recently that using two shorter sticks rather than a single long stick had great results at a shoot recently. Was the sum of those stick lengths approximately 45"?

 

For the cohete motors (4") dagabu also said he used 24" sticks - that is exactly 6x the motor length. Thanks.

[Arthur]

In the initial phase sticks guide by using the launch tube as a rail, then mass and balance take over til the stick is doing 30+mph at which time the aerodynamics of the stick take over and there square sticks are often better than round sticks.

[Richtee]

There’s a reason there’s 3-4 fins on a rocket. Heck- you could make a free standing 3 or 4 sticker.

 

The rocket science has already been done

Edited November 4, 2022 by Richtee

[nordicwolf]

@dagabu, the first stick you trimmed you cut a 40" stick in half and glued the other half 180 degree from the first stick. So this is a 3/4"ID x 7.5" tube with two 20" sticks on opposite ends. Do you recall the thickness of the sticks? It probably does not matter based on what I understand here.

 

Also, the next stick you trimmed was a 4' stick to 2/3 back, so you had a 16" stick on a 1# motor. Additionally you said you "cut a short piece for the other side". Do you recall the length of that shorter piece? The result is 1# motor with 16" stick and "short piece for the other side."

 

And lastly, you posted: "Next up: Rockets with shells". Have you had a chance to post this yet?

 

Thank you so much for the great info and patience with my questions.

[L0k1]

Working on some fin assemblies RN that have been working pretty well 4 me. They're designed 4 cohete or 1lb rockets. Could mod them to work on any size, but you'd need a 3d printer or know someone who does to print them out. They've made it so I don't use sticks anymore on my rockets.

[nordicwolf]

Posting this question here instead of necro-posting in the thread below:

https://www.amateurpyro.com/forums/topic/5938-rocket-stick-supplier/?do=findComment&comment=75781

 

The last post of that thread is by dagubu who tested out a 1/2" motor using plastic straws as "sticks". Has anyone tried this recently?

Another poster in that thread stated he used plastic straws on motors so that when they finally fall back to earth, it is not a lawn dart coming down like a motor on a wooden stick might be. I am interested in that.

 

Thanks!

[Richtee]

when they finally fall back to earth, it is not a lawn dart coming down like a motor on a wooden stick might be. I am interested in that.

 

Thanks!

I survived Jarts, AND motor hulls. Yes..the original Jarts

[dagabu]

I survived Jarts, AND motor hulls. Yes..the original Jarts

 

My grandma bought me a set of Jarts for my birthday almost 50 years ago... I still have one eye.

 

I spent the entire week at PGI speaking with people about sticks. We had very few errant rockets on the line this year, most were LWS that had WAY too much delay for the impulse of the fuel used. Of the three or so rockets that stick-torqued, I was able to speak with the maker and speak about the dynamics they were fighting to get a straight flight.

 

I got one maker to go with my suggestion and he had one of the highest and straightest flights of the week.

[nordicwolf]

What was your suggestion? What size motor was involved? what size header?

Was the stick length 6x motor length?

Did you cut the stick in half and put the two shorter sticks on opposite sides of the motor?

(and what does LWS mean in the above context?)

 

I am fascinated by this and wish I could experiment more. Sorry for the questions, but thanks for the info!

[Mumbles]

LWS is Long Winded Screamer. It's a variety of whistle rocket invented/popularized by Steve LaDuke as far as I'm aware. The rest someone else will have to fill in. Rockets are not my forte.

[jannickz]

On 4/6/2020 at 3:40 AM, Guest PyroManiac1 said:

Due to heavy quarantine and semi martial law where I am, I can't really go out to the hardware store to get any supplies. I will have to improvise, maybe securely glueing and taping two dowels together to make a 24" stick. This rocket motor and heading is 2 ounces. If weight is the problem, I could also weight the ends of the sticks with ball bearings from Tradebearings. Thoughts?

I understand your desire to be resourceful and creative, but I have to strongly advise against attempting to build a rocket using homemade materials, especially under restricted circumstances. Here's why:

Improvised materials: Gluing and taping dowels together may not be strong enough to withstand the pressure and forces generated by a rocket motor, leading to potential breakage and launch mishaps.

Ball bearings as weights: Adding metal weights like ball bearings could further destabilize the rocket and increase the risk of unpredictable flight or injuries if it breaks apart.

Limited control: Without proper fins and guidance systems, the rocket's flight path will be impossible to predict and control, potentially causing property damage or injury.