New Tripoli Unified Safety Code

[tsmith1315]

I see this reference to site dimensions in the Range Safety Guidelines:

"FSO personnel shall be aware of the largest motor that can be supported by the site
area given the table in the High Power Rocketry Safety Code"

But the only table I can find is the Safe Distances table, am I missing it?

 

[Steve Shannon]

I see this reference to site dimensions in the Range Safety Guidelines:

"FSO personnel shall be aware of the largest motor that can be supported by the site
area given the table in the High Power Rocketry Safety Code"

But the only table I can find is the Safe Distances table, am I missing it?

No, I think that’s the table you have to be aware of, but you also have to be aware of the launch site dimensions that are required by FAR 101.25, which is freely available:

Federal Register :: Request Access

www.ecfr.gov

 

[AlexBruccoleri]

A switch needs to be there per the rules....no added failure.
The second, pyro switch, I consider a great addition to safety as it DISCONNECTS and SHUNTS the pyro's avoiding any possibility of errant fires due to static, RF or miss-handling.

Yes, you can power up the altimeters then turn on the pyro's - altimeters don't get from boot to pyro check that fast.
With the pyro's off, the pyro check fails.....just restart if you can't switch two switches fast enough.
And this avoids any power-on "burps" from altimeters.

We have HUNDREDS of flights with this arrangement.....HUNDREDS.

Enough with the unfounded worry over switch failure - they don't fail, people do.
Most failures regarding electronics are pilot error....not HW.

Switches do fail. Also if they use internal springs and they wear out, the can have momentary interrupts. Also putting switches on the outside of the rocket can be dubious as well. If the rockets hits itself during deployment, it is possible, though unlikely, to turn a switch off. Switches inside the airframe, or wires taped, do not have this failure mode. Anyway I do not want to go on a long switch rant, other than to say the current safety code is fine in my view and fliers just need to be responsible for their rockets.

 

[Tractionengines]

I do not want to go on a long switch rant, other than to say the current safety code is fine in my view and fliers just need to be responsible for their rockets

Agreed... good enough. Everyone needs to be responsible for their rockets and actions.

 

[tsmith1315]

No, I think that’s the table you have to be aware of, but you also have to be aware of the launch site dimensions that are required by FAR 101.25, which is freely available:

Federal Register :: Request Access

www.ecfr.gov

Thanks!

Wording matters- I misread/misinterpreted the quote as "...the site area given by the table in the High Power Rocketry Safety Code".

We have neighbors callously breaking ground in a nearby field that will affect my site dimensions. I want to be sure there will still be an acceptable location for a launch complex.

 

[Steve Shannon]

Thanks!

Wording matters- I misread/misinterpreted the quote as "...the site area given by the table in the High Power Rocketry Safety Code".

We have neighbors callously breaking ground in a nearby field that will affect my site dimensions. I want to be sure there will still be an acceptable location for a launch complex.

I think there are site dimension tables somewhere but I don’t find them right away. Using the rules in FAR 101.25 works well though. The rules in FAR 101.25 are basically the same as NFPA 1127 as well.
We still need to clean up all those various places that reference the previous separate safety codes, but we haven’t forgotten.

 

[FredA]

Switches do fail. Also if they use internal springs and they wear out, the can have momentary interrupts. Also putting switches on the outside of the rocket can be dubious as well. If the rockets hits itself during deployment, it is possible, though unlikely, to turn a switch off.

ALL FUD!

I hope to fly a rocket enough times to suffer a switch failure due to wear.
I use "inverted V" contact types with a long wiping area so they don't suffer from momentary intermittent.
I also use redundant contacts on the power so they have less of possibility of intermittent power issues...these switches are 4PDT....the power switch in the photo uses all four contact sets to switch altimeter power. Now that we put trackers in a rocket, they typically have two sets for the altimeter and two for the tracker.
BRIEF (vibrations caused) intermittent interruptions DO NOT MATTER - altimeters have input caps that will ride through vibrations and pyro's will still fire.
Lastly, the switches DO NOT protrude outside the body so the possibility of being deactivated due to contact is very, very low.

Again - we as a team ALL do this and have suffered zero problems across hundreds of flights.

Now -- go back to my story about the found rocket:
Substitute who found the rocket to an innocent bystander unfamiliar with rockets - such as your landowner, his children, a sheriff, etc..
Have an bad outcome from their encounter and imagine the results.....Injury? Loss of a flying field? Worse.....

Make you rocket friendly to non-rocket people.
It's not hard. It's reliable. And just might save your bacon......

 

[AlexBruccoleri]

BRIEF (vibrations caused) intermittent interruptions DO NOT MATTER - altimeters have input caps that will ride through vibrations and pyro's will still fire.

That is only true on some altimeters and NOT what two manufactures told me when I asked. they said millisecond-scale interrupts could be okay, but not longer.

I am not going to argue with you about solid switches and implementations. I think solid screw switches are great and easy to disarm too. I am sure you have a good setup, but not all fliers will. The issue of switches is BALANCE. If you start adding more requirements for switches, you add the risk of fliers making mistakes and having rockets come in ballistic. That is also a threat you should think about too. The current safety code strikes a good balance in my view.

 

[UhClem]

The rules in FAR 101.25 are basically the same as NFPA 1127 as well.

Not really. They are equivalent in the sense that if you locate your launch pads in the exact center of your NFPA 1127 compliant launch site you will meet the FAA requirement for separation from persons/property (I have always wondered exactly what is meant by "property") not associated with the launch. But NFPA 1127 allows putting launch pads a lot closer to the site edge than its center.

 

[FredA]

they said millisecond-scale interrupts could be okay, but not longer.

That's really all you need for vibration type intermittent.
Put the switch in an orientation so the spring loading is not aligned with thrust.
Use an inverted V contact that only gets better with some side load.
Careful switch selection and use of redundant contacts greatly improve immunity.
Think about all the people who blindly use key switches ..... what do they know about their contacts and they NEVER use a redundant set of contacts.

Being a EE, this is all second nature to me.
CAREFUL device selection is always the first step toward success.

I've given up on impacting the rules - too much FUD because people fear/don't-understand electronics.
Most problems are Pilot Error and I realize people are already overloaded.

However, I put this out [every chance I get} to make people aware there are better ways to do things and to point out that although YOU know how to disarm your rocket, probably nobody else does and that's a danger once lost.

 

[AlexBruccoleri]

That's really all you need for vibration type intermittent.

I am not sure about that, and I have heard stories from other experienced fliers who claim brown out from either the switch or battery connection caused an in-flight reset and a crash.

I am not looking to argue about your setup or what is possible. It seems you know what you are doing and I am glad you are showing/helping others with solid switch and wiring design. Regarding policy, I disagree. I concur a partially deployed rocket is a danger, but I argue rockets coming in ballistic is a bigger and more likely danger. The Tripoli and NAR rules try to balance these and I feel they do a good job.

 

[sharkbait]

That's really all you need for vibration type intermittent.
Put the switch in an orientation so the spring loading is not aligned with thrust.
Use an inverted V contact that only gets better with some side load.
Careful switch selection and use of redundant contacts greatly improve immunity.
Think about all the people who blindly use key switches ..... what do they know about their contacts and they NEVER use a redundant set of contacts.

Being a EE, this is all second nature to me.
CAREFUL device selection is always the first step toward success.

I've given up on impacting the rules - too much FUD because people fear/don't-understand electronics.
Most problems are Pilot Error and I realize people are already overloaded.

However, I put this out [every chance I get} to make people aware there are better ways to do things and to point out that although YOU know how to disarm your rocket, probably nobody else does and that's a danger once lost.

I am not an EE, but I did stay at a Holiday Inn Express last night, and I have used about every type of switch available without failure, key, screw, slide, toggle, pull pin, push button, and even the much maligned Schurtner Rotary switch. Certain switches won’t be dis-armed by someone stumbling by unless they have the correct pin, the correct size and type of screw driver or worse yet the proper key. I agree with Fred that most issues are flyer error or abuse, or poor set ups. I don’t agree with the Fauci philosophy that if one switch is good then two are better and why not three or maybe four. I have twisted also, tuck, tape, and double hole, like everything else there are pro and cons to all three. As for the tuck, it’s just like most of the switches, the proper tool makes it simple to dis-arm, that’s why I have my paper clip hook tool to extract the wires. YMMV

 

[gtm3323]

Thank you Bob, Steve, and the rest of the Board to have the new safety completed and published. All the hours we spent on it paid off. What a process and many revisions!

 

[plugger]

Just wanted to chime in and say great work. It's nice having a single unified safety code document!

 

[plugger]

Personally, I think ANYONE who approaches an armed rocket needs to be able to disarm the rocket.
I think methods like single-hole twist-n-tuck, key-switches, WiFi switches and hidden screws-switches deep inside a rocket are NOT SAFE in this regard.

THIS is not that hard to do:
View attachment 516267

And as a club we have a hard and fast rule of not touching anyone's rocket in the field without their permission. And it's not failed us yet either despite thousands of rockets being launched.

 

[jimzcatz]

What he said!!

 

[FredA]

And as a club we have a hard and fast rule of not touching anyone's rocket in the field without their permission. And it's not failed us yet either despite thousands of rockets being launched.

An you NEVER left a rocket on the field --- you find 100% every time too, right????

 

[jimzcatz]

Correct. I won't touch a live rocket. Now a fully deployed one, that's a different story. I'll assist in the recovery of those.

 

[AlexBruccoleri]

An you NEVER left a rocket on the field --- you find 100% every time too, right????

Nothing is 100% but many clubs require fliers to retrieve their rockets. Read the bottom of Metra's policy.

General Launch Information | Metra Rocket Club

metrarocketclub.org

 

[alexzogh]

I am not an EE, but I did stay at a Holiday Inn Express last night,....

John, If I take your first sentence out of context, it's laugh-out-loud funny...... I think all of us should post a qualifier before offering our opinion on subjects we may not know enough about.

my qualifier: I'm not a doctor, but I do like a good murder-mystery

 

[PieroAcme]

Question..

In the Range Safety Guidelines V1.3 page 15 you find

Individuals flying rockets meeting the following criteria will require high power certification:
o Rockets powered by rocket motors not classified as model rocket motors per NFPA 1122, e.g.:
- Average thrust in excess of 80.0 Newtons
- Total impulse of 160.01 Newton-seconds or more
- Contains in excess of 2.2 ounces (62.5 grams) of propellant
- Hybrids (regardless of impulse)
- Sparky Motors (regardless of impulse). Note that some “F” and “G” motors fall into this category.
o Is propelled by a combination of model rocket motors having an installed total impulse of more than 320 N-Sec or
o Is propelled by a combination of model rocket motors having more than a total of 125 g (4.4 oz) of propellant weight; or
o Rockets that weigh more than 53 ounces (1500 grams).

But NFPA 1122 defines High power rocket , not High power model rocket motors that are instead defined into NFPA 1125 chapters 7.6, 7.7 . Here the motors are classified as High power motors if these contain more than 125 g not 62.5.
Where 62,5g propellant comes from ?

Thanks in advance for the clarifications

 

[jimzcatz]

125 grams is total propellant weight before a waiver is required.

 

[Steve Shannon]

Question..

In the Range Safety Guidelines V1.3 page 15 you find

Individuals flying rockets meeting the following criteria will require high power certification:
o Rockets powered by rocket motors not classified as model rocket motors per NFPA 1122, e.g.:
- Average thrust in excess of 80.0 Newtons
- Total impulse of 160.01 Newton-seconds or more
- Contains in excess of 2.2 ounces (62.5 grams) of propellant
- Hybrids (regardless of impulse)
- Sparky Motors (regardless of impulse). Note that some “F” and “G” motors fall into this category.
o Is propelled by a combination of model rocket motors having an installed total impulse of more than 320 N-Sec or
o Is propelled by a combination of model rocket motors having more than a total of 125 g (4.4 oz) of propellant weight; or
o Rockets that weigh more than 53 ounces (1500 grams).

But NFPA 1122 defines High power rocket , not High power model rocket motors that are instead defined into NFPA 1125 chapters 7.6, 7.7 . Here the motors are classified as High power motors if these contain more than 125 g not 62.5.
Where 62,5g propellant comes from ?

Thanks in advance for the clarifications

For the United States, FAR 101.25 is a federal regulation which defines the difference between class 1 (model rockets), class 2 (high power rockets), and class 3 (advanced high power rockets). For the new safety code it made more sense to refer to federal regulations which are freely available to our members as our rules rather than NFPA 1122, 1125, and 1127 which are not universally adopted and which cost a significant amount to purchase.
Obviously different places have different regulations but FAA rules and regulations are a good starting point. As pointed out by the safety code our members are expected to know and follow their local laws and regulations; Tripoli simply cannot track all of them.

 

[sharkbait]

John, If I take your first sentence out of context, it's laugh-out-loud funny...... I think all of us should post a qualifier before offering our opinion on subjects we may not know enough about.

my qualifier: I'm not a doctor, but I do like a good murder-mystery

Got to put some humor in some of these threads to keep it a little lighter, I am glad you got it and enjoyed it.

 

[plugger]

An you NEVER left a rocket on the field --- you find 100% every time too, right????

And you have magical batteries that last for days or weeks which would cause the above to be an issue? Please provide links here, as I'm interested in this magical tech you EEs have access to that us mere mortals don't.

 

[cwbullet]

It is funny how the switch conversation/argument always comes up. Wireless, twist wires, voltage switches, etc argument will continue till we are all gone. I think we all have to accept that people have different preferences and if it can be done safely, accept it and move along.

 

[FredA]

people have different preferences and if it can be done safely, accept it and move along.

Yes, please.
Offered her as help/education/perspective - hard to believe some people went to HATE over this.

 

[AlexBruccoleri]

Yes, please.
Offered her as help/education/perspective - hard to believe some people went to HATE over this.

Nobody is upset over good wiring education. Your suggestion of changing the safety code and outlawing switch designs which you do not like, was my concern.

 

[cwbullet]

Yes, please.
Offered her as help/education/perspective - hard to believe some people went to HATE over this.

I have no issue with a discussion. I have an issue with the attitude that twisted wires have no place in rocketry mentality. There are switches that was unsafe just as much as there are techniques of twisting wires that are unsafe. We should promote safe behavior no matter what type of switch you use.

 

[plugger]

I find the timing curious, one would think if this was the hill you wanted to die on noise would have been made before the new Unified Safety Code was released.

But I don't think anyone that approaches a rocket should pick it up, as I can easily see someone grabbing a rocket laying on the ground horizontally, rotating it to vertical before turning the switches off (wherever they may be placed), and having an ejection charge go off as a result.