Do model rockets create fire? If so, should one refrain from launching one in a low grass field?

[Steve Shannon]

They most definitely can start a fire at launch and I was personally responsible for one around February 1981 in Orlando unfortunately. We held a contest and I was flying a glider I believe. The large field had tall grass/weeds and they were very dry because it was winter with no rain in a while. We didn't pay attention at launch because we were watching the flight and when someone turned around we saw a rather significant fire had started in the dead weeds and was rapidly spreading. All of use tried to stop it to no avail and I remember after the heat had very slightly blistered my forehead. The local fire department came out and put it out after it had gotten very large. I know of two other instances of large brush fires starting down here that needed the fire department to put out. Be very careful and always keep an eye on the ground after a launch to stop it immediately before it spreads and cannot be stopped. Here's a picture of the Orlando 1981 fire after it was put out, very bad.

Our safety codes (and NFPA Codes) require clearance of flammable materials for a significant distance from the launch pad. That definitely includes dead weeds, grass, cow manure, etc. It’s the least enjoyable job of range preparations, but it’s possibly the most important.
If that simple, but labor intensive task is done, there is much less risk of launch pad fires, but as you say, they certainly can happen.

 

[lakeroadster]

Our safety codes (and NFPA Codes) require clearance of flammable materials for a significant distance from the launch pad. That definitely includes dead weeds, grass, cow manure, etc. It’s the least enjoyable job of range preparations, but it’s possibly the most important.
If that simple, but labor intensive task is done, there is much less risk of launch pad fires, but as you say, they certainly can happen.

How much clearance / significant distance? Just wondering what the specification is. I may need to start taking a weed whip and a yard rake with me to the launch site in the future.

 

[Steve Shannon]

How much clearance / significant distance? Just wondering what the specification is. I may need to start taking a weed whip and a yard rake with me to the launch site in the future.

From NFPA 1127 - multiply by 1.5 for sparkies:

 

[rkoenn]

So the glider spit out the motor, and that caused the fire? Or was it caused by the motor exhaust from the launch of the glider?

It was caused by the engine exhaust exiting onto the dry brush. We were on the edge of the field in a mowed down section of short grass but it was a bit windy and the conditions were amenable to easily starting a fire. I remember one other down in Palm Bay about 20 years ago or so flying off the street with similar heavy brush on the empty lots in the area. There were many HP flights going up. One of the rockets spit the igniter off into the brush, or some similar event, and started a large brush fire. I was already preparing to leave when it happened so left shortly after. The guys tried to put it out without success. As I exited the large expanse the field was on to a main road a fire truck I passed a fire truck headed to the location the fire started at.

 

[UhClem]

The biggest fire risk IMO isn't at the pads, but if a rocket goes sideways and ejects while on the ground. Northern Colorado Rocketry has had 2 large grass fire accidents in the last 10 years and both of them were from an ejection charge. There have been a few very small fires around the pad, but they were easily spotted and controlled before getting too big. The ejection charge fires though, required the local fire department.

Fires started far away from the pads take more time to get to. A bad two stage design (modified Fat Boy springs to mind) can do this.

I cancelled the launch I would normally host tomorrow because it is so dry. The field is undeveloped city park department property that gets mowed once a year. (June, this year) Two fires have started on that field from ejection charges. Both caused by using motors with ejection charges in saucer/pyramid type things. Once the ejection charge went off on the ground and the other time at least 10' in the air.

Easily controlled because I am on my second Smoke Chaser. But I don't care to start anything now.

 

[Paul Howard]

I know I sound like a broken record, but in the last year I've had Estes Recovery Wadding burn an ember all the way to the ground TWICE which really creeped me out with the thought of a breeze taking it out of the green grassy soccer fields where I launch and into the potentially dry forested or dry grass fields surrounding the launch area. Now I build with Ejection Baffles and use Nomex Parachute Blankets or Parachute Buckets and try to avoid recovery wadding. In the few instances of using recovery wadding, I spray it with water to make it slightly damp right before installing everything to launch. I launch-by-bike, i.e.- everything is in/on a backpack and I ride my bike to launch (or fly rc gliders), so I carry at least 1 extra quart not intended for drinking as well as 1 quart to drink and a mini-fire extinguisher. I also have a pretty big blast deflector made of HardiPlank siding material. I pretty much avoid launching in summer now since it's a real risk and a bit of a complaint-magnet especially after the really big bad fires we had in Oregon 2 years ago that are still on my mind and a lot of other people's minds. What's really annoying is that with all the safety measures I take (and I wish more people doing rockets would take) and with the fire danger and complaint potential about model rockets, our town still allows fireworks for the 4th of July when everything is nice and dry and ready to burn and that is deemed "OK".

 

[lakeroadster]

From NFPA 1127 - multiply by 1.5 for sparkies:

Thanks Steve, much appreciated.

So to clarify, for G or smaller motors, 50 feet equals a 25-foot radius from the launch pad?

 

[UhClem]

How much clearance / significant distance? Just wondering what the specification is. I may need to start taking a weed whip and a yard rake with me to the launch site in the future.

NFPA 1122 just says "the area around" the launcher. No distance specified. (4.12.2)

Important if you are using a low slung thing like an Estes Port-A-Pad but much less so for taller pads.

 

[mh9162013]

Parachute Buckets

Is that like a parachute blanket that's sewn into the shape of a cup or bucket?

 

[Zeta]

I was just curious about this since I am looking for a spot in NY where my rocketry club and I can launch a rocket for testing. We know of a couple of places (none confirmed to be allowed yet) but some of these places are grassy parks. Thanks to those who reply.

Yep : https://www.necn.com/news/national-...9AyMxDgi9NKHaqlTF8cet3y4n0b2UqbGVoKL0Z6WW7DB8

 

[Ez2cDave]

They most definitely can start a fire at launch and I was personally responsible for one around February 1981 in Orlando unfortunately. We held a contest and I was flying a glider I believe. The large field had tall grass/weeds and they were very dry because it was winter with no rain in a while. We didn't pay attention at launch because we were watching the flight and when someone turned around we saw a rather significant fire had started in the dead weeds and was rapidly spreading. All of use tried to stop it to no avail and I remember after the heat had very slightly blistered my forehead. The local fire department came out and put it out after it had gotten very large. I know of two other instances of large brush fires starting down here that needed the fire department to put out. Be very careful and always keep an eye on the ground after a launch to stop it immediately before it spreads and cannot be stopped. Here's a picture of the Orlando 1981 fire after it was put out, very bad.

It was caused by the engine exhaust exiting onto the dry brush. We were on the edge of the field in a mowed down section of short grass but it was a bit windy and the conditions were amenable to easily starting a fire. I remember one other down in Palm Bay about 20 years ago or so flying off the street with similar heavy brush on the empty lots in the area. There were many HP flights going up. One of the rockets spit the igniter off into the brush, or some similar event, and started a large brush fire. I was already preparing to leave when it happened so left shortly after. The guys tried to put it out without success. As I exited the large expanse the field was on to a main road a fire truck I passed a fire truck headed to the location the fire started at.

Bob,

I would have guessed a "fuse-type" DT that landed before the fuse reached the Snuffer Tube.

Bad fire but, at least, no one was injured and no structural damage occurred to any buildings.

Dave F.

 

[Steve Shannon]

Thanks Steve, much appreciated.

So to clarify, for G or smaller motors, 50 feet equals a 25-foot radius from the launch pad?

Thanks Steve, much appreciated.

So to clarify, for G or smaller motors, 50 feet equals a 25-foot radius from the launch pad?

Yes, 4.15.1 specifies a diameter equal to the distance in the table.

 

[rkoenn]

Bob,

I would have guessed a "fuse-type" DT that landed before the fuse reached the Snuffer Tube.

Bad fire but, at least, no one was injured and no structural damage occurred to any buildings.

Dave F.

It was simply the ignition but everyone was watching the flight and so that is a bit of an assumption. There was no DT on it and it might have been an RC glider, I don't recall. By the time anyone looked back at the pad it had gotten rather large and although we tried to put it out it was simply too large with plenty of dead scrub brush to feed it.

 

[Sandy H.]

I'm not a fan of fires at all. I personally don't fly sparky motors, but I respect the right for others to do so under proper field conditions. Even a BP motor can cause a fire as others above mention. It is very good to keep water fire extinguishers around, soak the area ahead of time and to keep multiple people vigilant looking for fire or smoke.

In my mind, after the win with the ATF, fire is the biggest risk to the hobby. Not trying to blow that out of proportion or be a hand waving person at all, but it is easy to let a fire start and hard to get it under control. The pictures above of the baseball fields are really pretty scary. I'm very glad the fire department and media chose to say it was an accident by people not trying to cause a problem, but to just enjoy a day outside. If things like that happen 10-20 times a year, I doubt the media will be as gentle.

Sandy.

 

[UhClem]

A recent fire near here was started by mowers and destroyed several homes.

When the fuel is dry almost anything can set it off. Another fire before that was attributed to a glass bottle in a trash can. (I have no idea how they can be sure of that.)

 

[rkoenn]

Is that like a parachute blanket that's sewn into the shape of a cup or bucket?

Recently I have been buying nomex blankets precut in specific sizes from eRockets to use to protect the chute. They work fine but I am only flying LP these days so they usually aren't too big. I attach them to the shock cord or somewhere else with a nomex line. He makes them in a number of sizes but of course if you can find large sheets of nomex cloth you could cut your own with the correct shears.

 

[Ez2cDave]

Recently I have been buying nomex blankets precut in specific sizes from eRockets to use to protect the chute. They work fine but I am only flying LP these days so they usually aren't too big. I attach them to the shock cord or somewhere else with a nomex line. He makes them in a number of sizes but of course if you can find large sheets of nomex cloth you could cut your own with the correct shears.

https://www.rocketryforum.com/threads/paper-parachute-protectors.168048

Those could easily be cut out of thin Nomex . . .

Dave F.