CATO's and Launch Pad Design

[lakeroadster]

When I see photo's of engine CATO's, such as Kevin Foss's Nike X C6 below, I wonder why launch pads don't have a 5 gallon bucket full of water under the rocket, instead of a flat steel plate?

The flat plate is great as a lateral distribution device....

If there was a bucket of water under the rocket.. the picture wouldn't be so awesome, but the launch site would be much safer.

As I understand it, the rocket was basically unscathed... there was nothing left of the engine but an empty casing.

Why not step up our game and try something different?

 

[rharshberger]

Would you like water sprayed all over the place and potentially on a cardboard model? Thats the only real reason I can think of besides transport and setup logistics ( its a pain to haul buckets/ water to launches), ease of setup is another reason for steel plates, and protecting the pads me hanical parts from corrosive exhaust products.

 

[KennB]

The event pictured took place at the 16th Anniversary Fliskits launch with CMASS on 15 September (sadly, the final Fliskits Anniversary Launch). Despite the patch of brown thatch by the pad, the grass was quite green and dew-soaked as we were setting up in the morning. The Amesbury Fire Department has declined to allow us to launch on this field, a city park, when we've had drought conditions.

If you look closely beyond the spectacle of the cato, you'll see Frank and Linda getting set up at another pad. The orange item on the ground near them is a water pump extinguisher, one of three we have placed around the field as part of our efforts to suppress any fire that may get started. NAR has annual allowances for sections to purchase safety equipment and we've outfitted ourselves through that.

For the 300+ launches that day, we had fewer than 5 catos; hauling 40 pounds of water for each of our 11 LPR and MPR pads would be quite an effort for relatively little increase in safety. It may be a good way for some to increase safety; if someone does it, I'd like to see some action shots.

 

[rharshberger]

Our club added a 250 gallon portable tank with electric pump and hoses this year for our biggest fire hazard launches June-July-August-September, its carried in the back of my F250, if we can't stop the fire with 250 gallons it aint gonna be stopped by us. The tank was donated (its a used fertilizer tote) and we added a Harbor freight pump and two hoses, it cost less than $200 dollars.

 

[lakeroadster]

Would you like water sprayed all over the place and potentially on a cardboard model?

Yes, I'd rather have a model rocket potentially damaged than a fellow human being.

 

[rharshberger]

Yes, I'd rather have a model rocket potentially damaged than a fellow human being.

As far as I am aware injuries in rocketry generally occur during prepping for flight, accidental ignition (usually at the pad), and inflight anomalies like instability and recovery failures into spectator areas. What we have for blast control works, and it protects the equipment and our setback distances protect the humans as much as possible. Flat plate blast deflectors could be angle to deflect exhaust in one direction as much as possible in the event of an accidental ignition on the pad.

 

[Steve Shannon]

When I see photo's of engine CATO's, such as Kevin Foss's Nike X C6 below, I wonder why launch pads don't have a 5 gallon bucket full of water under the rocket, instead of a flat steel plate?

The flat plate is great as a lateral distribution device....

If there was a bucket of water under the rocket.. the picture wouldn't be so awesome, but the launch site would be much safer.

As I understand it, the rocket was basically unscathed... there was nothing left of the engine but an empty casing.

Why not step up our game and try something different?

The best way to prevent people from being struck and possibly injured by pieces of the catoed motor is to increase the distance between the pad and the people.

 

[lakeroadster]

As far as I am aware injuries in rocketry generally occur during prepping for flight, accidental ignition (usually at the pad), and inflight anomalies like instability and recovery failures into spectator areas. What we have for blast control works, and it protects the equipment and our setback distances protect the humans as much as possible. Flat plate blast deflectors could be angle to deflect exhaust in one direction as much as possible in the event of an accidental ignition on the pad.

The best way to prevent people from being struck and possibly injured by pieces of the catoed motor is to increase the distance between the pad and the people.

With all due respect.. is that really the "best" way? Is it really "as much as possible"? It is a way, but the photo above shows the folly of saying it is the best way. The only reason nobody got hurt is the pieces didn't hit anybody, due to pure luck.

We can do better... when somebody suggests we up our game and try something different why aren't the responses more open to some R&D?

 

[Steve Shannon]

With all due respect.. is that really the "best" way? Is it really "as much as possible"? It is a way, but the photo above shows the folly of saying it is the best way. The only reason nobody got hurt is the pieces didn't hit anybody, due to pure luck.

We can do better... when somebody suggests we up our game and try something different why aren't the responses more open to some R&D?

Feel free to R&D all you like. The first question to Research is “why don’t we do this?” Don’t resent those who provide an answer you don’t like.
Unless you launch from underwater many of those pieces of catoed motor might not even get wet. A bucket underneath would only catch pieces projected downward. Those pieces look as though they were blown horizontally by the case fragmentation rather than bouncing off the blast plate.
In that photo it’s difficult to tell whether the pieces actually even reached the people at the next pad or if that picture actually appears shortened by a telephoto lens.

 

[Charles_McG]

Feel free to R&D all you like. The first question to Research is “why don’t we do this!

As a research chemist, I think that could be better phrased as “has this been tried before?” - it’s why research begins in the library.

The question recalls the punch line to my favorite college statistics joke (each exam started with a joke on the over page) : ‘No one publishes negative results’.

 

[Kosmo]

The best way to prevent people from being struck and possibly injured by pieces of the catoed motor is to increase the distance between the pad and the people.

Agree with this. The other launch pads look awfully close in that picture (acknowledge that perspective might distort things.)

Also, it's not even a sure thing that the blast plate is what caused those flares to go horizontal. It was an engine CATO, they could've gone in any direction. Seems like a big assumption to suggest that a water bucket underneath would have prevented that.

 

[tomsteve]

i think it would be wise to find information about this launch before wanting to rewrite the safety codes. those people behind could be further away than it appears or they may not be at the safe distances listed in both NAR and TRA safety codes.
this is a very safe hobby due to safety codes. yes, a 5 gallon bucket of water could be put under each pad. then every club would have to spend money to redesign their pads. the people that set up launches do a LOT of work to set them up. have a launch like airfest where theres a jillion pads......welp...i think youd need to volunteer to take care of the filling and emptying of buckets( i couldnt see clubs forkin out money for a tank and trailer to go to every pad and fill em so someones gonna do a LOT of walkin). might even have to pay for the water depending on location of launch.

there is no one way a cato happens. parts can fly in every direction so a bucket of water under the pad wouldnt help much,imo.
a bucket of water wouldnt have done anything for that flaming ball above the rocket in that photo

along with,"has this ever been tried before?" another question would be,"how many catos have caused injury out of how many launches in a year?" numbers dont lie- if you find theres a problem with cato injuries and have statistics to back it up, maybe something should change.

 

[Steve Shannon]

As a research chemist, I think that could be better phrased as “has this been tried before?” - it’s why research begins in the library.

The question recalls the punch line to my favorite college statistics joke (each exam started with a joke on the over page) : ‘No one publishes negative results’.

You’re right; that’s the better question.

 

[Rex R]

so the grain separated from the case and the nozzle blew out/it roman candled(C6 BP motor) the long lens makes the fore and aft distance look shorter. if you're thinking to have the bucket catch the exhaust then I hope you are also prepared to go and refill said bucket after every launch.
Rex

 

[KennB]

Those pieces look as though they were blown horizontally by the case fragmentation rather than bouncing off the blast plate.
In that photo it’s difficult to tell whether the pieces actually even reached the people at the next pad or if that picture actually appears shortened by a telephoto lens.

Agree with this. The other launch pads look awfully close in that picture (acknowledge that perspective might distort things.)
Also, it's not even a sure thing that the blast plate is what caused those flares to go horizontal. It was an engine CATO, they could've gone in any direction. Seems like a big assumption to suggest that a water bucket underneath would have prevented that.

We use discs slid over the rods for our blast deflectors. Some of them are a bit warped and could send projectiles off in a horizontal direction. From what I read in the FB post, the motor casing was intact and the rocket not damaged. I wasn't at the LCO position when it happened so I don't have first hand info.

Our 11 pad circular set up places each pad 15 feet away from its neighbor; if we need to, we can launch on pad 2 while someone is setting up on pad 1 - this only happens when we have a very busy and only with a heads-up to the people at the adjacent pads. And when we need 30 feet of separation, we make sure people are two pads away from the action. The people in the photo are at pad 7, 60 feet away around the circumference and a good 40+ feet away as the flames fly.

The photo was taken with a phone camera; I don't know how those do with foreshortening compared with a traditional telephoto lens.

 

[Kosmo]

Kenn, after all that, I still say it's a spectacular photo.

 

[KennB]

Kenn, after all that, I still say it's a spectacular photo.

That it is. Sharp, high-shutter rate cameras capture all kinds of great failures.

 

[Chris_H]

The best way to absolutely prevent ANY risk of fire, or ANY risk to human health, is to not engage in practices which could potentially resut in these events.


Do you wish to ban rocketry?





Life is inherently fragile. Life can change in the blink of an eye. This is part of what makes life, and living rich and valuable.

If you are not okay with the risks, you should not put yourself into a situation which is beyond that where you are comfortable.

Be careful, and look out for the safety of others, always.

Anyone who is present at a rocket launch should be (made) already aware that rocketry has inherent risks.

A ballistic descent due to non-deployment is a real risk, yet there is no -guarantee that it will not happen. An accident could easily be 'not pretty'. If you are not okay with the risks, you should not be present. You signed a risk waiver, right?

Personally, I am 'more scared' of the potential of having a bad experience with a crackhead on a vacation to Florida. But I still go... And yes, there have been close calls.


A bucket of water beneath a rocket motor sounds like a complete mess. "Next up... "..........." on an N5800.. can we please have a fresh bucket of water...'


Always, yes, if there is a better way, then yes. Let it be fully demonstrated.


A voice calling for 'a bucket of water' under rockets on the pad.... Please, no.

 

[lakeroadster]

The best way to absolutely prevent ANY risk of fire, or ANY risk to human health, is to not engage in practices which could potentially result in these events.

Hmmm? Nobody in this thread, other than you, has mentioned setting the goal as "preventing ANY risk".

..... Don’t resent those who provide an answer you don’t like. .... Unless you launch from underwater many of those pieces of catoed motor might not even get wet. A bucket underneath would only catch pieces projected downward. Those pieces look as though they were blown horizontally by the case fragmentation rather than bouncing off the blast plate.
In that photo it’s difficult to tell whether the pieces actually even reached the people at the next pad or if that picture actually appears shortened by a telephoto lens.

I don't resent anyone.. I'm simply at a loss as to why new ideas don't seem to be very well received here?

As mentioned above, the motor case was intact. It puked out the bottom... and out the top.

.... if you're thinking to have the bucket catch the exhaust then I hope you are also prepared to go and refill said bucket after every launch.
Rex

How so? has it ever been tried? Likely no loss of water at all for a LPR like the one being discussed.. it was a C6 Estes motor.

I'm thinking the bucket would be a foot below the bottom of the rocket.

I guess I'll try it... putting it on my "bucket list"

 

[Steve Shannon]

Nice one!

For motors that fail out the ends a bucket of water catch basin would be nice. Most pads would need some redesign, but it could be done. Even though I’m skeptical, I’m interested in seeing your results.

 

[markkoelsch]

With all due respect.. is that really the "best" way? Is it really "as much as possible"? It is a way, but the photo above shows the folly of saying it is the best way. The only reason nobody got hurt is the pieces didn't hit anybody, due to pure luck.

We can do better... when somebody suggests we up our game and try something different why aren't the responses more open to some R&D?

Those people in the back ground are too close. That might be a “legal” distance, but they are clearly too close irregardless of rules. Distance is key.

 

[rharshberger]

Those people in the back ground are too close. That might be a “legal” distance, but they are clearly too close irregardless of rules. Distance is key.

Mark check post 15, the distance is an illusion, they were at least 40' from the cato's burning debris as they were standing near a pad 60' from where the cato happened.

 

[BA_Incognito]

Whenever you are dealing with a potential explosive situation, distance is always your friend. Based on chemical compounds and their explosive tendencies, we can calculate how far you need to be from them to be safe should an explosion occur. For the large quantities that are shipped over the highways and by rail you can find these distances in the DOT Emergency Response Guidebook (https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/ERG2016.pdf - starts on Page 296). Like these tables, the NAR and Tripoli Safety Guides have done the same type of measurements. The nice thing about distance is it doesn't cost you anything and it keeps folks safe. So while you can look at developing other solutions (perhaps a containment system that restricts the distance the material may travel), it is always going to cost more and be more complex than simply increasing the distance from the device.

 

[tomsteve]

Those people in the back ground are too close. That might be a “legal” distance, but they are clearly too close irregardless of rules. Distance is key.

mark, with all due respect, i think you are coming to conclusions without all of the necessary information, which quite a bit was given above about the launch-"The people in the photo are at pad 7, 60 feet away around the circumference and a good 40+ feet away as the flames fly."
we dont know how far the flaming derbis flew. if it only went 10', then whats the problem? why would they be too close?

 

[lakeroadster]

Our 11 pad circular set up places each pad 15 feet away from its neighbor; if we need to, we can launch on pad 2 while someone is setting up on pad 1 - this only happens when we have a very busy and only with a heads-up to the people at the adjacent pads. And when we need 30 feet of separation, we make sure people are two pads away from the action. The people in the photo are at pad 7, 60 feet away around the circumference and a good 40+ feet away as the flames fly.

The photo was taken with a phone camera; I don't know how those do with foreshortening compared with a traditional telephoto lens.

Not that any thing is against pre-established safety codes, but I'm struggling to understand your statement of distances?

It looks to me based on the photo, and your description, that Frank and Linda are more like 15 feet away... not 40 feet.

What am I missing?

 

[Nytrunner]

You're missing the Launchpad that's right next to them. The origin of the circle is to the left of the photo

 

[guywad]

Actually, the center of the circle is to the right of the picture. What is missing is that the Cato occurred on pad 3. Frank and Linda are standing at pad 7 and pad 8 is the other pad in the picture. Pads are numbered 1-11 clockwise around the circle.

Guy.

 

[Nytrunner]

Ah, my mistake. I figured those three were consecutive curving to the left. So their are three more pads out of frame to the left

 

[lakeroadster]

You're saying there are 3 launch pads out of screen between the CATO and Frank /Linda ????

 

[guywad]

Yes, pads 4, 5 and 6 are out of frame to the left. It is a big circle of pads purposely designed to give the required distances between pads for low power motors. Kenn is planning on posting a diagram illustrating our layout.