High power test question.......

[Glasspack]

Please forgive me if this seems like a stupid question....... But A High Power rocket motor starts at total impulse of 160.01 - 320.00 Newtons (an H motor)
and doubles with each subsequent class of motor. For example.... 360.01- 640.00 Newtons (an I Motor) .........All the way to 20,480.01 - 40,960.00 Newtons (an O motor)
A Model Rocket Motor must have a total propellant weight less than 125 Grams to be classified as NOT High Power.

I know there are members on here WAY smarter at Rocket Science than I, so I am not afraid to ask and further my knowledge !!


An F90 motor with 40 Grams of propellant does NOT seem to meet the classification of High Power Rocket Motor, & yes, I know the F Class is 40.01 - 80.00 Newtons
but it does state "hypothetically"

Given JUST the info, below why is the only correct answer "C" ? Seems to me it should be "A" & "C"

Question A17 Which of the following (hypothetical) rocket motors is NOT a High Power Rocket motor? A. An F90 with 40 grams of propellant B. An H60 with 62 grams of propellant C. A G35 with 66 grams of propellant D. All of the above are High Power Rocket motors

 

[Neutronium95]

Please forgive me if this seems like a stupid question....... But A High Power rocket motor starts at total impulse of 160.01 - 320.00 Newtons (an H motor)
and doubles with each subsequent class of motor. For example.... 360.01- 640.00 Newtons (an I Motor) .........All the way to 20,480.01 - 40,960.00 Newtons (an O motor)
A Model Rocket Motor must have a total propellant weight less than 125 Grams to be classified as NOT High Power.

I know there are members on here WAY smarter at Rocket Science than I, so I am not afraid to ask and further my knowledge !!


An F90 motor with 40 Grams of propellant does NOT seem to meet the classification of High Power Rocket Motor, & yes, I know the F Class is 40.01 - 80.00 Newtons
but it does state "hypothetically"

Given JUST the info, below why is the only correct answer "C" ? Seems to me it should be "A" & "C"

​

Question A17 Which of the following (hypothetical) rocket motors is NOT a High Power Rocket motor? A. An F90 with 40 grams of propellant B. An H60 with 62 grams of propellant C. A G35 with 66 grams of propellant D. All of the above are High Power Rocket motors

There's also a restriction on average thrust. Any motor with more than 80N of average thrust requires a HPR certification, even if it has less than 160 Ns of impulse. The same goes for all sparky motors.

 

[Titan II]

There's also a restriction on average thrust. Any motor with more than 80N of average thrust requires a HPR certification, even if it has less than 160 Ns of impulse. The same goes for all sparky motors.

That info is not available in the question. He asked [emphasis added]:

"Given JUST the info, below why is the only correct answer "C" ? Seems to me it should be "A" & "C"

 

[Neutronium95]

That info is not available in the question. He asked [emphasis added]:

"Given JUST the info, below why is the only correct answer "C" ? Seems to me it should be "A" & "C"

The average thrust is part of the motor designation. That's what the 90 in F90 means.

 

[Glasspack]

I was NOT aware of the Average Thrust Limit with the Rule .............. And I can't find it in the LPR or HPR Safety Code posted on NAR Web site.
But I will keep looking
Thank You !!

 

[Neutronium95]

I was NOT aware of the Average Thrust Limit with the Rule ..............

Thank You !!

Happy to help.

 

[Steve Shannon]

I was NOT aware of the Average Thrust Limit with the Rule .............. And I can't find it in the LPR or HPR Safety Code posted on NAR Web site.
But I will keep looking
Thank You !!

Here’s the definition from the Tripoli Unified Safety Code:

High Power Rocket Motor: A motor which meets any of the following criteria:
	Exceeds 80 Newtons average thrust, or An impulse greater than 160 Newton-seconds up to 40,960 Newton-seconds (upper limit of an O motor), or Which has had metal particles added to intentionally create a shower of sparks effect.

 

[Steve Shannon]

Better yet here’s the definition from the NAR page:

Where Is The Line Between Model and High Power Rocketry?​

A rocket exceeds the definition of a Model Rocket under NFPA 1122 and becomes a High Power Rocket under NFPA 1127 if it:

• Uses a motor with more than 160 Newton-seconds of total impulse (an “H” motor or larger) or multiple motors that all together exceed 320 Newton-seconds; or
• Uses a motor with more than 80 Newtons average thrust (see rocket motor coding); or
• Exceeds 125 grams (4.4 ounces) of propellant; or
• Weighs more than 1,500 grams (53 ounces) including motor(s); or
• Uses a hybrid motor or a motor designed to emit sparks; or
• Includes any airframe parts of ductile metal.

In addition, under FAA rules (FAR 101.22), a rocket exceeds the definition of a Class 1 Model Rocket and becomes a Class 2 High Power Rocket if it weighs more than 1500 grams (53 ounces). For additional information on Class 2 Rockets, see the Understanding FAA Regulationspage.

 

[SolarYellow]

As long as we are on this, would a scale-like IQSY Tomahawk with actual aluminum sheet metal around the body tube at the fin can, if the pieces were fastened through the fins with tiny, scale-like screws, count as "substantial metal parts," thereby moving it into Class 2? Would a reasonable distinction be if the rocket was structurally capable of flying safely without the plates, thereby making them just really cool OCD scale decoration?

 

[Glasspack]

Thank you Steve,

My version must be out dated I have this from FAA 14 CFR Part 101 (I thought is was dated Dec 2022)
Doesn't say anything about average thrust....

Subpart C— Amateur Rockets
§ 101.21 Applicability.
[Doc. No. FAA–2007–27390, 73 FR 73781, Dec. 4, 2008, as amended by Docket No. FAA–2022–1355, Amdt. No. 101–11, 87 FR
75846, Dec. 9, 2022]
§ 101.22 Definitions.
The following definitions apply to this subpart:
[Doc. No. FAA–2007–27390, 73 FR 73781, Dec. 4, 2008]
(b) No person may operate a moored balloon or kite between sunrise and sunset unless its mooring lines
have colored pennants or streamers attached at not more than 50 foot intervals beginning at 150 feet
above the surface of the earth and visible for at least one mile.
(a) This subpart applies to operating unmanned rockets. However, a person operating an unmanned rocket
within a restricted area must comply with § 101.25(g)(2)) and with any additional limitations imposed by
the using or controlling agency.
(b) A person operating an unmanned rocket other than an amateur rocket as defined in § 1.1 of this chapter
must comply with 14 CFR Chapter III.
(a) Class 1—Model Rocket means an amateur rocket that:
(1) Uses no more than 125 grams (4.4 ounces) of propellant;
(2) Uses a slow-burning propellant;
(3) Is made of paper, wood, or breakable plastic;
(4) Contains no substantial metal parts; and
(5) Weighs no more than 1,500 grams (53 ounces), including the propellant.
(b) Class 2—High-Power Rocket means an amateur rocket other than a model rocket that is propelled by a
motor or motors having a combined total impulse of 40,960 Newton-seconds (9,208 pound-seconds) or
less.
(c) Class 3—Advanced High-Power Rocket means an amateur rocket other than a model rocket or high-power
rocket.

 

[bad_idea]

My version must be out dated I have this from FAA 14 CFR Part 101 (I thought is was dated Dec 2022)
Doesn't say anything about average thrust....

FAA doesn't care about average thrust. NFPA does. Note Steve quoted from NFPA. The safety codes take both FAA regulations and NFPA guidelines into account.

 

[OzHybrid]

. Deleted

 

[OzHybrid]

Better yet here’s the definition from the NAR page:

Where Is The Line Between Model and High Power Rocketry?​

A rocket exceeds the definition of a Model Rocket under NFPA 1122 and becomes a High Power Rocket under NFPA 1127 if it:

• Uses a motor with more than 160 Newton-seconds of total impulse (an “H” motor or larger) or multiple motors that all together exceed 320 Newton-seconds; or
• Uses a motor with more than 80 Newtons average thrust (see rocket motor coding); or
• Exceeds 125 grams (4.4 ounces) of propellant; or
• Weighs more than 1,500 grams (53 ounces) including motor(s); or
• Uses a hybrid motor or a motor designed to emit sparks; or
• Includes any airframe parts of ductile metal.

In addition, under FAA rules (FAR 101.22), a rocket exceeds the definition of a Class 1 Model Rocket and becomes a Class 2 High Power Rocket if it weighs more than 1500 grams (53 ounces). For additional information on Class 2 Rockets, see the Understanding FAA Regulationspage.

There used to be a definition in NFPA 1127 that there was a max propellant weight for a motor of not HPR of 62.5g over was HPR. This seems to have been removed from 1122 and 1127. There is now just a bad definition.
The old 62.5g definition for a single motor was useful as it was at the cusp of exceeding the other limits. You could easily get past the 80N average thrust.

So now we could have LPR/MPR motors up to 125g of propellant by the current definition. But as you get roughly past half the weight, you're likely going to be exceeding the maximum average thrust allowed if you get to around the 62.5g level.




With the current definitions in 1122 and 1127, the Answer is C @Steve Shannon What happened to the 62.5g??????

 

[jmasterj]

As long as we are on this, would a scale-like IQSY Tomahawk with actual aluminum sheet metal around the body tube at the fin can, if the pieces were fastened through the fins with tiny, scale-like screws, count as "substantial metal parts," thereby moving it into Class 2? Would a reasonable distinction be if the rocket was structurally capable of flying safely without the plates, thereby making them just really cool OCD scale decoration?

Yes to the first and no to the second. Doesn't really relate to the motor topic here, though.

 

[Steve Shannon]

Thank you Steve,

My version must be out dated I have this from FAA 14 CFR Part 101 (I thought is was dated Dec 2022)
Doesn't say anything about average thrust....

Subpart C— Amateur Rockets
§ 101.21 Applicability.
[Doc. No. FAA–2007–27390, 73 FR 73781, Dec. 4, 2008, as amended by Docket No. FAA–2022–1355, Amdt. No. 101–11, 87 FR
75846, Dec. 9, 2022]
§ 101.22 Definitions.
The following definitions apply to this subpart:
[Doc. No. FAA–2007–27390, 73 FR 73781, Dec. 4, 2008]
(b) No person may operate a moored balloon or kite between sunrise and sunset unless its mooring lines
have colored pennants or streamers attached at not more than 50 foot intervals beginning at 150 feet
above the surface of the earth and visible for at least one mile.
(a) This subpart applies to operating unmanned rockets. However, a person operating an unmanned rocket
within a restricted area must comply with § 101.25(g)(2)) and with any additional limitations imposed by
the using or controlling agency.
(b) A person operating an unmanned rocket other than an amateur rocket as defined in § 1.1 of this chapter
must comply with 14 CFR Chapter III.
(a) Class 1—Model Rocket means an amateur rocket that:
(1) Uses no more than 125 grams (4.4 ounces) of propellant;
(2) Uses a slow-burning propellant;
(3) Is made of paper, wood, or breakable plastic;
(4) Contains no substantial metal parts; and
(5) Weighs no more than 1,500 grams (53 ounces), including the propellant.
(b) Class 2—High-Power Rocket means an amateur rocket other than a model rocket that is propelled by a
motor or motors having a combined total impulse of 40,960 Newton-seconds (9,208 pound-seconds) or
less.
(c) Class 3—Advanced High-Power Rocket means an amateur rocket other than a model rocket or high-power
rocket.

As @bad_idea pointed out, don’t try to align FAA rules with NFPA sample code. FAA rules are mostly concerned with air safety (with a nod to fire safety) while NFPA 1122 and 1127 are sample code with an emphasis on user safety. The distinction between Class 1 rockets and Class 2 rockets affects the need for a COA, certificate of authorization, NOT whether a rocket motor requires certification to buy and use. In the Tripoli Unified Safety Code we attempt to help clarify that difference in this note:
Special Note for Tripoli Launches: Because the current FAA definition of a Model Rocket is based on propellant weight rather than impulse, it's possible to have a Class 1 rocket ("Model Rocket") that contains a High Power Rocket Motor, an H motor with less than 125 grams of propellant. That does not mean it may be flown from the Model Rocket Launch Area. Any rocket which contains a High Power Rocket Motor must be launched from the High Power Launch Area according to the High Power Safe Distances. Such a rocket would still require at least an L1 certification.

By the way, this is part of the reason Tripoli want to a new safety code (Tripoli Unified Safety Code) last year which doesn’t rely on NFPA sample code. It’s not a rejection of NFPA in any way, but it reflects the notion that we are free to establish and publish our own rules so our members don’t have to carry a copy of NFPA. In doing so we hope to reduce confusion.

 

[Steve Shannon]

There used to be a definition in NFPA 1127 that there was a max propellant weight for a motor of not HPR of 62.5g over was HPR. This seems to have been removed from 1122 and 1127. There is now just a bad definition.
The old 62.5g definition for a single motor was useful as it was at the cusp of exceeding the other limits. You could easily get past the 80N average thrust.

So now we could have LPR/MPR motors up to 125g of propellant by the current definition. But as you get roughly past half the weight, you're likely going to be exceeding the maximum average thrust allowed if you get to around the 62.5g level.




With the current definitions in 1122 and 1127, the Answer is C @Steve Shannon What happened to the 62.5g??????

I didn’t do it.

That language went away with the 2012 revision of NFPA 1122 and 1127. This TRF thread discusses it:
https://www.rocketryforum.com/threads/most-powerful-mpr-engine.40755/

 

[tsmith1315]

My version must be out dated I have this from FAA 14 CFR Part 101 (I thought is was dated Dec 2022)
Doesn't say anything about average thrust....

As @bad_idea pointed out, don’t try to align FAA rules with NFPA sample code. FAA rules are mostly concerned with air safety (with a nod to fire safety) while NFPA 1122 and 1127 are sample code with an emphasis on user safety.

This is a confusion area, since the two don't align. To restate what Steve and bad_idea said:
FAA defines rocketry flights as Class 1/2/3, and which flights require FAA involvement. It does not define HPR, and the breakpoints aren't the same as HPR Level 1/2/3

NFPA defines HPR, and that's what the test question covers.


The graphic in this post may be helpful:
https://www.rocketryforum.com/threads/class-1-launch-rules-for-mpr.180378/post-2445098

 

[samb]

My recollection is that the 2012 revision was one of the consequences of the settlement of the ATF lawsuit. Gary Rosenfield was there. Mark Bundick, Bill Stine…

 

[Steve Shannon]

My recollection is that the 2012 revision was one of the consequences of the settlement of the ATF lawsuit. Gary Rosenfield was there. Mark Bundick, Bill Stine…

If a person is truly interested in NFPA revision history, they’re all documented on the NFPA site with the requests that led to them.

 

[Glasspack]

Thank you ALL !!

My mistake was looking for the explanation in Part 101 of the FAA rules....
But as Steve pointed out I should have looked for the answer in NFPA 1127
I will keep reading NFPA 1127 and CFR 14 Part 101 !

Found it..... Here it is ....... Para. 3.3.15.3 Model Rocket Motor

Thanks Again !!

 

[cls]

In the end, just memorize the correct answer, get 100% on the test, and move on.

 

[Worsaer]

To Steve’s earlier comment, if you learn and adhere to the Tripoli Unified Safety code, you won’t need to learn and apply codes from multiple sources. Someone’s already done the hard work for you to bring into one place!

 

[Glasspack]

Thank you CLS But I value
the knowledge, not to JUST pass the test

 

[cls]

Thank you CLS But I value
the knowledge, not to JUST pass the test

Oh I completely agree!

But there is no making sense of things that were established arbitrarily and evolved separately and could change on a whim.

Part of test taking strategy is knowing when to move on.

 

[Steve Shannon]

Thank you ALL !!

My mistake was looking for the explanation in Part 101 of the FAA rules....
But as Steve pointed out I should have looked for the answer in NFPA 1127
I will keep reading NFPA 1127 and CFR 14 Part 101 !

Found it..... Here it is ....... Para. 3.3.15.3 Model Rocket MotorView attachment 585741

Thanks Again !!

My quote above was actually from the NAR website where they explain the delineation:
https://www.nar.org/high-power-rocketry-info/

 

[OzHybrid]

I didn’t do it.

That language went away with the 2012 revision of NFPA 1122 and 1127. This TRF thread discusses it:
https://www.rocketryforum.com/threads/most-powerful-mpr-engine.40755/

Hi Steve,
Was the change disseminated? I don't remember that happening.
it's bad enough that we have to play both "Where's Wally". AND "Spot the difference" when the rules get changed But it is worse when no-one tells their chums when they know where wally is .
Could I ask that when the parent organizations notice these things that the members get notified of the key changes you find. This will prevent Wally sneaking upon us all.
While I expect our governments to be disingenuous and say we published the changes to the law, you should have read them, the reality is that it's not practigable to check every law before you do something. Initially you need to be across all the rules. After that you get just the updates to the rules.
I don't re-read the highway code in full before every car journey. Nor should I have to.
You didn't do it. And I still love you....
But I've seen the 62.5 g rule quoted on this forum recently. So please make sure we all know.
And I have quoted it recently too. So I was wrong( you heard it here first).

 

[samb]

TO ALL WHOM IT MAY CONCERN:

THE PROPELLENT WEIGHT THRESHHOLD FOR FAA CLASS 2 WAS RAISED TO 125 GRAMS IN 2012. BOTH TRIPOLI AND NAR SAFETY CODES WERE UPDATED TO REFLECT THIS .

IT WASN’T STEVE’S FAULT !

 

[OzHybrid]

TO ALL WHOM IT MAY CONCERN:

THE PROPELLENT WEIGHT THRESHHOLD FOR CLASS 2 WAS RAISED TO 125 GRAMS IN 2012. BOTH TRIPOLI AND NAR SAFETY CODES WERE UPDATED TO REFLECT THIS .

IT WASN’T STEVE’S FAULT !

Is this the Brittney thing?

Steve has broad shoulders and knows when I say "Your car has an oil leak", it's not the same as"You completely destroyed my brand new driveway, mate."
NFPA 1122, 1125 and 1127 are the basis for all international rocketry rules. In Australia, our rules refer to them.
The crux of what I'm saying, is "How do we ensure that regulatory changes are shared to those affected by those changes?" I don't think just updating the rules is enough. They need to be updated with an addendum of what the changes from the previous rules were. Those exist in the individual NFPA rules, but are not disseminated under our Tripoli or NAR consolidated rules. Which is where most go, to find out what's required, as they are a distillation of the various applicable pieces of legislation into a single document.
In this case the 62.5g rule was removed for a single motor ( however, it's still there in Australia under the pyrotechnics licencing requirements, sort of ish).
There seems to be a mention of the limit being in the Range Safety guidelines as late as 2021. The link to them no longer works. https://www.rocketryforum.com/threads/hybrids-2021.165685/post-2130407

The phrase is "TO WHOM IT MAY CONCERN" , Usually followed by "Without Prejudice" This can then be followed by your personal opinion of where I should locate my golf clubs...... Everyone is entitled in law to have an opinion and as long as it's not defamatory, share it. ( I'm not a lawyer. YMMV)

 

[samb]

@RocketScientistAustralia I was trying to make light of the fact that, evidently, a change made 11 years ago hasn't been fully disseminated yet. I don't have an answer to this problem and I certainly have no experience with regulation in your neck of the woods. As has been mentioned here by @Worsaer, "... adhere to the Tripoli Unified Safety code*, you won’t need to learn and apply codes from multiple sources. Someone’s already done the hard work for you to bring into one place".
* Or NAR

 

[Steve Shannon]

Hi Steve,
Was the change disseminated? I don't remember that happening.
it's bad enough that we have to play both "Where's Wally". AND "Spot the difference" when the rules get changed But it is worse when no-one tells their chums when they know where wally is .
Could I ask that when the parent organizations notice these things that the members get notified of the key changes you find. This will prevent Wally sneaking upon us all.
While I expect our governments to be disingenuous and say we published the changes to the law, you should have read them, the reality is that it's not practigable to check every law before you do something. Initially you need to be across all the rules. After that you get just the updates to the rules.
I don't re-read the highway code in full before every car journey. Nor should I have to.
You didn't do it. And I still love you....
But I've seen the 62.5 g rule quoted on this forum recently. So please make sure we all know.
And I have quoted it recently too. So I was wrong( you heard it here first).

Norm,
I don’t know if it was broadcast by Tripoli at the time, but NFPA has an entire process of publishing changes and soliciting comments so it’s very likely that it was discussed. It was four years before i joined the board and six years before I joined the NFPA technical committee. I can’t possibly go back and retroactively announce decade old changes and I don’t think you want me to.
To your point I think ATF still has a dead exception for rocket motors that includes 62.5 g of propellant as an upper limit. Of course since the lawsuit APCP is completely unregulated by ATF, but the exception is still there causing confusion. That might even be where Australian authorities got their pyrotechnics rule.
But, you are right. The organizations should make a concerted effort to notify their members of changes and help them understand how the changes affect them. If I’ve failed to do that I’ll try harder.