Indestructible Rocketry parts, Good or bad?

For those who are content to get the same thrill (without the sxtra cost) of the High Power Peple
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#1 Indestructible Rocketry parts, Good or bad?

Post by Commander » Thu, 13 Sep 18, 21:59 pm

I noticed this video on Facebook today.

VIDEO DELETED AT OWNERS REQUEST Sorry guys, the guy stomping on the tube was afraid that all of our membership might...? It was just the video of a leg basically stomping on a short section of fiberglass BT-60 which didn't crush.

So it seems like a lot of parts for hobby rocketry are getting stronger and stronger. Contrary to the general perception, that isn't a good thing in a lot of cases.

Like the smaller automobiles of the past 40 years or so, hobby rockets are meant to "crumble" or crush upon impact rather than remain intact. This is a safety feature. If anything untowards occurs in flight, there is no Range Safety Officer flipping a switch to self-destruct an errant rocket. With larger motors available, the risk to life and limb becomes even greater.
I remember hearing a story from many years ago how a model rocket manufacturer would launch a rocket against a plate glass window to show how the rocket, not the glass would break. This along with the professionally manufactured motor or engine, would prove how safe the hobby was.
While we do need strength in our building materials, a forethought must be given to whether that strength makes the item safer or more dangerous. With our hobby having it's first fatality at a launch in its 60 or so years, we need to keep an eye out for other "improvements" which might not be really what we want.
:cc:
Last edited by Commander on Fri, 14 Sep 18, 04:53 am, edited 2 times in total.
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#2 Re: Indestructible Rocketry parts, Good or bad?

Post by Commander » Thu, 13 Sep 18, 22:15 pm

Unfortunately, the previous discussion s we had on this issue were in the old place, but I was able to find a link to the page.

old Cantina Appropriate Nose Cone Material
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#3 Re: Indestructible Rocketry parts, Good or bad?

Post by Commander » Thu, 13 Sep 18, 22:22 pm

One picture/a thousand words
rocket vs windshield.png
rocket vs windshield.png (109.58 KiB) Viewed 64 times
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#4 Re: Indestructible Rocketry parts, Good or bad?

Post by Commander » Fri, 14 Sep 18, 04:35 am

The last vestige of the weak, threaten legal action.
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#5 Re: Indestructible Rocketry parts, Good or bad?

Post by Commander » Fri, 14 Sep 18, 05:12 am

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#6 Re: Indestructible Rocketry parts, Good or bad?

Post by tmacklin » Sun, 16 Sep 18, 01:21 am

I recall an incident where a boy scout was impaled by an Estes X15 model rocket that was launched on a windy day, weather cocked and went "cruise missile mode", striking the child in the armpit and stopping just short of his heart. I believe this was a troop from north Texas and happened in Oklahoma. I saw this report on Rocketry Planet.

https://www.cpsc.gov/Recalls/2007/risk- ... el-rockets

After this kit was recalled by the CPSC, I spotted one still on the shelf at a Hobby Lobby in Denton, TX and advised the store manager of the recall. It was removed.

Once again it would appear that the long standing NAR rules against flying rockets when the winds exceed 20 mph were not observed. and once again it was a scout leader who apparently gave the green light for the launch.

Model rocketry is an inherently dangerous activity, especially when the safety rules are ignored.

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#7 Re: Indestructible Rocketry parts, Good or bad?

Post by Commander » Sun, 16 Sep 18, 05:38 am

So of course I go sticking my nose into others people business and get denigrated for trying to explain something. I should know better, but according to the sentiment of those responding, I'm just a troll with no knowledge of anything to do with rocketry. I am trying to hold the hobby back.

First and foremost, I am not going to re-argue points I have made elsewhere. I have too little time to be wasting it trying to explain to those who wish not to see the truth in things the possibilities of their misconceptions. Besides they are going to do what they want anyway. To which I say, Steven remember this line and practice it over and over till it sounds very sincere, "I'm sorry about the loss of your sons life ma'am, but truly lighter weight, structurally stronger materials are safer in hobby rocketry." I'm sure that mother will gladly accept her loss with your heartfelt rationale.

2) I am not the internet safety police nor even model rocketry's police. I really need to remember to keep my mouth shut with people asking others to hold their beers while they show them something. Those doing the holding and showing just aren't going to listen anyhow till something bad happens then plead ignorance.

3) One of the main things I was going to try and explain (but failed miserably since I don't use these formulae anymore on a regular basis) is that when the the mass of an object is decreased, the mass is accelerated at a greater speed. The greater speed affects the force of the object exponentially since it is squared. Couple that with a material that can sustain higher loading before failure, and you have a lethal object.

4) I was accused of spreading "fake news" (newest catch phrase for thus wishing to avoid true research and facts) for mentioning that the rocketry fatality of a few years ago was affected by the materials of the rocket. The other parties continually repeating that the rocket used a paper body tube. I have no idea where they got their information, but every article that mentioned the material that I read (through eye witness accounts) stated it was made from 4" PVC tubing.

5) The posters made mention that fiberglass tubing was safe as long as the rules are followed basically. This at its core is an oversimplification. Any rocket can become a lethal projectile even when all of the rules and procedures are followed. Without going into all the myriad ways that things could go bad, I'll just mention one for an example. This example assumes all safety rules and procedures are followed up to the point of deflection of the rocket from it's flight path. The cause of the deflection? A bird flies into the rocket.

6) I was also lambasted for mentioning that the founding fathers of model rocketry wanted their rockets to crumple upon an impact. With all I have read, it would take me some time to find it, but I am sure it is out there. If anyone knows of some references, I would appreciate the help.

To bring this all to a close, maybe a simple question would suffice. If a rocket was knocked off course and headed straight towards you, would you rather have the rocket body tube be paper or fiberglass?
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#8 Re: Indestructible Rocketry parts, Good or bad?

Post by tmacklin » Sun, 16 Sep 18, 14:06 pm

I read both of the links that you posted and, ironically, the TRF link was a thread I originated. I read all 110 posts in that thread and direct your attention to post number 94 by "stealth6" which contains a letter from the NAR by Ted Cochran, dated 21 November 2015. In that letter, Mr. Cochran states that the rocket that struck and killed Mr. Mike Bentley was about 4 inches in diameter and had a body tube made from cardboard with a plastic nose cone.

It is what it is.

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#9 Re: Indestructible Rocketry parts, Good or bad?

Post by Commander » Sun, 16 Sep 18, 15:04 pm

So I stand corrected on the materials of the fatal rocket.

And upon further reflection, lightening mass at some point will have a less forceful effect on impact. Once optimal mass is achieved, lowering the weight will give the effect (safer?) most people think of. Of course getting a rocket down to optimal mass is often easier said than done, and even then, the builder aware of such things will add mass if the peak point is dropped below.
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#10 Re: Indestructible Rocketry parts, Good or bad?

Post by tmacklin » Sun, 16 Sep 18, 16:04 pm

Commander wrote:
Sun, 16 Sep 18, 15:04 pm
So I stand corrected on the materials of the fatal rocket.

And upon further reflection, lightening mass at some point will have a less forceful effect on impact. Once optimal mass is achieved, lowering the weight will give the effect (safer?) most people think of. Of course getting a rocket down to optimal mass is often easier said than done, and even then, the builder aware of such things will add mass if the peak point is dropped below.
As my pop used to say, "Accuracy is my motto, I mever nake mistakes." Relying on early news reports is always risky especially given the ignorance of the reporters. Peace.

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