[FFT] Hope this isn't beating a dead horse, but...

do I need Level 1 to launch a triple-G cluster at a NAR sanctioned event?

I ask because all the standard literature I read on model and HPR likes to describe things in terms of motor classes (G and below vs. H and above), but I never find a reference saying that "yes, you can buy G's without a Level

1, but you will need the Level 1 to launch a cluster of them".

Or maybe I'm just looking in the wrong place?

Reply to
bit eimer
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PS:

The Model Rocket Safety Code limit on N-sec is 320 (an H engine), not 160 as one would expect if the max engine is supposed to be a G. Plus the Launch Site Dimension Table at the end of the MRSC goes up to a double G.

Just more confusion.

Reply to
bit eimer

The NAR model rocket safety code

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rule

7, on "size" says you can have up to 320 newton seconds of total impulse.

Which G motors were you going to use?

If they are at the top end of the range (160 n-s each) then you can have two in a model rocket. Three "high end" Gs would total to 480 n-s and would be a level one high power rocket.

Three G motors at the low end (80 n-s) of the range totals to 240 n-s which is legal for a model rocket.

The launch site dimensi> do I need Level 1 to launch a triple-G cluster at a NAR sanctioned event? >

Reply to
Will Marchant

Most likely. You can have up to 125g of propellant. Three baby G's might theoretically get under that, but in all likelihood will exceed it, making it an HPR thus requiring certification.

You can have a total combined impulse of up to 320Ns. Three Econojet G's might be under that, three (common) 120Ns G's will not.

Also, if you indeed had a full G motor - 160 Ns - it would surely be over 62.5g of propellant, the max allowed per motor while still being considered MR. BTW, this is why most G's don't exceed ~120Ns - to stay under the 62.5g limit, not for HPR considerations, but for DOT requirements.

Here's something I cooked up way long ago. It attempts to sort it all out.

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HTH. Doug

Reply to
Doug Sams

In general if you're flying a single motor your limit is the upper end of the G range,160N-s, that's as high as you can go without a Level 1 cert. If you're flying a cluster however you can legally sneak into the next higher power range, in this case H at 160.01-320N-s. The same thing can be done at Level 1 to fly in the J range, btw. That fact has me considering delaying my L2 attempt on purpose until after LDRS, if I decide to go. There's something about a Level 1, flying 2 I-motors in the new LOC altitude contest, that appeals to my sense of panauch. Of course the rocket would be called "New Kid On the Block" ;-) On field dimensions. That's a pragmatic rule of thumb in my mind. Bigger motors, higher flights/more spectacular "goofs", more space needed, no brainer there. The same with the separation from the LCO and the pad. Conditions may require fudging abit, but as long as things keep to the spirit of safety there seems small need to get out there with a micrometer.

Chuck

bit eimer wrote:

describe things in terms of motor classes (G and below vs. H and above), but I never find a reference saying that "yes, you can buy G's without a Level 1, but you will need the Level 1 to launch a cluster of them".

Reply to
Zathras of the Great Machine

Wow - beautifully concise document. Answers all questions. Too bad NAR can't make it that clear.

Downside is that:

1) I can't fly my recently purchased triple-G cluster without a Level 1

2) I can't GET a Level 1 using my recently purchased triple-G cluster

Soooo, that means I have to get something else for a Level 1 qual flight. Hmmmm, is that still a downside...

Thanks,

Reply to
bit eimer

You're right, it is that simple. Too bad that NAR's description tries to OVER-simplify it by focusing on single engine size (G or smaller vs H or bigger) - that's what makes it confusing.

Reply to
bit eimer

Reply to
Will Marchant

Wow, thanks for that tip!

Reply to
bit eimer

There are no SINGLE USE MODEL ROCKET G motors that are any where near 160 NS. The reason is the 62.5g propellant limit for a model rocket motor. The best you can get within this limit is around 120-130 NS.

Even if you pick some roughly 100ns G motors, so that 3 stay under the 320ns model rocket limit, you'll be over the 125g propellant limit. 2 G or 3 F motors will put you right at that limit. Anything more is HPR.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

You could fly it on a cluster of 3 F motors. You don't say what the rocket is, but a cluster of 3 F50s should lift it as long as the whole thing is still under the 1500g limit.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

All of the limits Fred mentions are clearly spelled out in the NAR Model Rocket Safety Code. Actually, the first 3 are covered by the certified model rocket motor requirement.

That all the motors have to be certified model rocket motors.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

Don't you think all this is needlessly convoluted for "safety code requirements"? ... especially, and ironically, since these particular requirements seem to have been intended, not so much to control a particular hazard, as to satisfy a historical/political desire to have a clear and arbitrary "administrative boundery" between "real Model Rocketry" and anything else!

-dave w

Reply to
David Weinshenker

Yes, I did not cover "certified" motors in my list since I was just covering weight.

If flying in CA, all pyrotechnic devices must be properly classified by the CA State Fire Marshal (CSFM). "Model Rocket Motor" is one classification. "High Power Rocket Motor" is another, and some motors that fall under the NAR/NFPA limits of Model Rocket Motor were submitted to the CSFM as High Power Rocket Motors and issued that classification, SO if you launch in CA and your permit is for launching Model Rockets, then you must only use motors that have the "Model Rocket Motor" CSFM Classification.

If you want your NAR or TRA insurance to remain in effect (a requirement of many launch site use permission agreements/permits), then they also have to be on the big list of certified motors recognized by those organizations.

-Fred Shecter NAR 20117

Reply to
Fred Shecter

State Fire

There's been some the other way too... motors that were CSFM registered as "model rocket" but would fall into the "high power category" when all NAR/NFPA limits are applied: the Aerotech single-use 24mm F101, for example, was over 80 N thrust but had a CSFM "model rocket" seal on its label.

-dave w

Reply to
David Weinshenker

-dave w

Would your town, county, fire marshal, city, et al., accept as inherently legal and safe the following?

horizontal launching of rockets? experimenting with warheads by 10 year olds? launching at the end of a small private airport? launching rockets without recovery devices, over populated areas?

If they didn't like some or all of these activities, without a universally accepted safety code, they'd have to write their own rule book to regulate this stuff. Isn't it easier to have everyone use the same set of rules? Who better to write them than the industry?

steve

Reply to
default

Exactly. So that motor could be flown on a site with a Model Rocket launching permit from the fire authority, but ONLY if you were not required to use NAR certified Model Rocket Motors only (like you are at most launch sites that require clubs obtain/maintain insurance coverage - either standard or special certificates/wording).

Bottom line: if any limit is violated or exceeded, it's not a "Model Rocket".

Reply to
Fred Shecter

How hard is it to build & fly a L1 rocket? - Not very. It won't kill him.

I know you don't like the cert system but it's not that big a deal. Consider that to cert you are just flying what you wanted to fly anyway.

Reply to
Phil Stein

what you are

cannot exceed 125 grams.

Yes, if you're gonna include FAA notification with item 6, it needs to be included with item 4, too. FAA notifcaition is required if the propellant mass exceeds 113g. (I know you know that.)

Doug

Reply to
Doug Sams

Thanks!

Reply to
Fred Shecter

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