No Substantial Metal Parts?

In the federal law defining Class 1 rockets we have the subject statement as part of their definition. I hate clumsy, generic and subjective wording like this. Has there ever been any clarification on what constitutes substantial? I've got L1 rockets that are all paper, wood and plastic except for some recovery hardware that I could fly on large G's and baby H's. Certainly those parts would not be considered substantial. Correct?

Correct. Screw eyes, quick links, swivels, etc. are not considered substantial.
Parts like the nose cone, airframe, fins, motor mount made from metal would be considered substantial.

Correct. Eye bolts, u-bolts, all thread, etc. don't qualify as "substantial".

I agree that based on reason and logic they shouldn't qualify but is it written anywhere? We all know how well reason, logic and federal law synchronize.....

fyrfytr310 said:

I agree that based on reason and logic they shouldn't qualify but is it written anywhere? We all know how well reason, logic and federal law synchronize.....

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Please try to relax. It's not written anywhere (in any other verbiage) that I know off. They are not out to get you. Enjoy your hobby. :grin:

fyrfytr310 said:

I agree that based on reason and logic they shouldn't qualify but is it written anywhere? We all know how well reason, logic and federal law synchronize.....

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Sure is check out FAR 101 there are several relevant sections on rocketry. No substantial metal parts is in Subpart C iirc.

fyrfytr310 said:

I agree that based on reason and logic they shouldn't qualify but is it written anywhere? We all know how well reason, logic and federal law synchronize.....

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I actually prefer the non specific general wording. Gives the hobby a little more wiggle room. More specific wording might have made metal reloadable motor casings a non starter.

Seems clear to me that the airframe needs to be substantially non metallic while hardware items can feature some metal components.

tab28682 said:

I actually prefer the non specific general wording. Gives the hobby a little more wiggle room. More specific wording might have made metal reloadable motor casings a non starter.

Seems clear to me that the airframe needs to be substantially non metallic while hardware items can feature some metal components.

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I used to work directly with FAA inspectors in my last job. Non-specific wording saved our butts several times. The key was to develop a good relationship with them and demonstrate that you knew what you were doing and everything you did was meant to comply with the regulations. We screwed up at times (usually paperwork problems), some quite serious, but we were never fined or faced sanctions. We had our wrists slapped and had to do fix everything, but that was the extent of it. Some of these FAA people were horribly anal when it came to details, but none of them were ever jerks about punishing us for honest mistakes.

There was one time... no, better not talk about that... even 15 years later.

The FAA wants to ensure that if, in the extremely highly unlikely event that your rocket hits an airplane, it won't puncture a hole in the airplane.

But as stated, we have internal metal parts, not the least of which is the motor casing!, and even the solid aluminum nose cone tips. So as long as you aren't building your airframes and fins out of metal, you're okay. And you might even get away with the fins....

I built a rocket with too thin plywood for fins. To stiffen it up I sandwiched the ply between two .043" pieces of soft sheet aluminum held together with aluminum Pop Rivets. The aluminum went over the fillet and onto the airframe about an inch and was riveted to it also. Stiffened them up enough to withstand the thrust of a Kosdon M2240. As it was my 3rd level rocket it was inspected by the 3rd line TAP and he had no problem with it.

What about the ProLine full scale ARCAS with CNC Aluminum fins?

dave carver said:

I built a rocket with too thin plywood for fins. To stiffen it up I sandwiched the ply between two .043" pieces of soft sheet aluminum held together with aluminum Pop Rivets. The aluminum went over the fillet and onto the airframe about an inch and was riveted to it also. Stiffened them up enough to withstand the thrust of a Kosdon M2240. As it was my 3rd level rocket it was inspected by the 3rd line TAP and he had no problem with it.

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Of course, that flight was FAA Class 2, and his question is about Class 1, which is more restrictive about metal.

As Bat-mite said, the FAA limits on Class 1 (weight, propellant, materials, etc) are chosen to avoid significant damage to a plane in the unlikely event it were to hit one.

TALON said:

What about the ProLine full scale ARCAS with CNC Aluminum fins?

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I was always under the impression that Class 2, and especially Class 3 rockets were allowed to use more metal than Class 1. For example, a lot of the ARLISS rockets use aluminum fins, and they are using M motors. And we have seen on youtube people doing all aluminum Class 3 rockets.

So I looked up Part 101, and didn't see anything that says more metal is allowed on Class 2 or 3 rockets. But apparently, there are people doing it, and have never heard anyone getting into trouble. I would imagine that a Class 3 waiver asks what the materials of the rocket are. So I imagine the FAA has allowed it in the past. Here is the link for Part 101.

https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&node=14:2.0.1.3.15#se14.2.101_122

CZ Brat said:

I was always under the impression that Class 2, and especially Class 3 rockets were allowed to use more metal than Class 1. For example, a lot of the ARLISS rockets use aluminum fins, and they are using M motors. And we have seen on youtube people doing all aluminum Class 3 rockets.

So I looked up Part 101, and didn't see anything that says more metal is allowed on Class 2 or 3 rockets. But apparently, there are people doing it, and have never heard anyone getting into trouble. I would imagine that a Class 3 waiver asks what the materials of the rocket are. So I imagine the FAA has allowed it in the past. Here is the link for Part 101.

https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&node=14:2.0.1.3.15#se14.2.101_122

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Actually, the only wording concerning metal is in the list of items involving Class 1 restrictions.

Given that metal is not mentioned in the class 2 and 3 list, it implies metal is not an issue as far as FAR part 101 is concerned.

The NAR high power safety code mentions that ductile metal is allowed when necessary.

Bat-mite said:

The FAA wants to ensure that if, in the extremely highly unlikely event that your rocket hits an airplane, it won't puncture a hole in the airplane.

But as stated, we have internal metal parts, not the least of which is the motor casing!, and even the solid aluminum nose cone tips. So as long as you aren't building your airframes and fins out of metal, you're okay. And you might even get away with the fins....

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Actually, I think a composite model or mid power rocket airframe could do as much damage to an aircraft as a metal airframe.

I think the no substantial metal rule was an outgrowth of the worry over "basement bomber" rocket builders that were hurting themselves stuffing black powder in metal tubing around the time model rocketry as we know it was born.

tab28682 said:

Actually, I think a composite model or mid power rocket airframe could do as much damage to an aircraft as a metal airframe.

I think the no substantial metal rule was an outgrowth of the worry over "basement bomber" rocket builders that were hurting themselves stuffing black powder in metal tubing around the time model rocketry as we know it was born.

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I would be quick to agree with you if it were found in NFPA-1127, but why would the FAA be concerned with basement bombers? Their concern is airspace.

FAA Class 3 rockets are advanced high power amateur rockets, not FAA Class 2 high power amateur rockets, nor FAA Class 1 model rockets. The FAA, and NAR under NFPA 1122, prohibit the use of substantial metal parts in FAA Class 1 model rockets. While there are no FAA prohibitions concerning the use of metal in FAA Class 2 or 3 amateur rockets, when high power certified NAR/TRA members use certified motors in FAA Class 2 rockets at sanctioned launches they must also comply with NFPA 1127 which is the unabridged safety code for both organizations. Only TRA permits the launch of preapproved Class 3 rockets which are by TRA definition research rockets not covered under NFPA 1127.

https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&node=14:2.0.1.3.15 lists the current FAA Part 101 rules.

Bob

Bat-mite said:

I would be quick to agree with you if it were found in NFPA-1127, but why would the FAA be concerned with basement bombers? Their concern is airspace.

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Actually, I would not be surprised at all if the FAA used the model rocket safety code as the basis for some the model rocketry part of FAR 101. Lack of metal in the model rocket airframes would tend to make things safer in the national airspace as well as in the basements of novice rocket motor makers.

The well know G Harry Stine booklet about model rocketry safety mentions that model rocket airframes were intended from the beginning to be light and frangible and non metallic, from before model rocketry was on the FAAs radar in any way. This makes me think this metal minimization concept was folded into the FARs from the model rocket safety code.

https://www.nar.org/pdf/40years.pdf

The FAA used some info from the AMA when working up the original Advisory Circular 91-57 concerning model aviation.