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Construction /Safety Code question: What constitutes "substantial metal parts"?

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mrichhcirm

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Obviously little things like snap swivels, eyebolts, motor hooks are OK. But I'm considering using this as a subframe/armature to sculpt a nosecone:

http://www.joann.com/activ-wire-mes...tm_source=google&utm_medium=cpc&utm_campaign=[ADL]%20[Shopping]%20Product%20Type%20-%20Margin%20[Desktop]%20[High]&gclid=Cj0KCQjw--DLBRCNARIsAFIwR25dHu3Ry-A05VrLa1WZE0x1hJ_Xc82fSjedJI4NlWVNDfBWZxSTpDoaAgRTEALw_wcB

I figure I would drape this over a lightweight balsa subframe, rough out the shape, and cover with tissue paper laid up with ModPodge (or maybe ultralight fiberglass w/ epoxy).

Because it's an expanded aluminum mesh, it certainly seems lightweight and crushable enough to be safe as long as I don't have any sharp bits sticking out...what do you think? Legal under the safety code?

Thanks,
Mike
 

rstaff3

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If I were RSOing and was told this I would pass it. If you glass the cone, there should be no use for the wire IMO.
 

Bat-mite

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I think "substantial metal parts," considering that the wording comes from the FAA, means, "anything that could punch a hole in an airplane." But probably really refers to metal airframes. I've seen aluminum fins, aluminum nose cone tips, aluminum motor casings, retainers, adapters ....
 

rstaff3

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What is allowed varies by whether sub-HPR or HPR. But not the answer to the question posed here.
 

mrichhcirm

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If I were RSOing and was told this I would pass it. If you glass the cone, there should be no use for the wire IMO.
The idea is to allow me to sculpt shapes that don't have the usual rotational symmetry of your garden-variety nosecone. Picture an Apollo LEM or airplane-type nose with protruding domes, canopies, etc. Or other shapes that don't have a cylindrical cross section.

Or maybe I could coat the mesh with Bondo, plaster, etc. and create a mandrel that I could lay up the shape on with FG. That could work too, I guess.
 

rcktnut

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I would think sculpting foam and laying that up with fiberglass would be easier than the method you are using.
 

Micromeister

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No substantial parts means simply:
NO metal Nose cones, Air-frames, Fin Cans or Fins.
With all the other materials currently available any kind of Metal for these major parts is simply unnecessary and are DANGEROUS In all impulse Hobby Rocketry.

To your question;
If I were the RSO and told you used a metal mesh under your FG, It would certainly be banded from flight on a general launch range with spectators in attendance.

If presented at a Ex launch than no problem.

Please keep in mind: our Safety code is not intended to protect us the rocket flyers, but to cover the unsuspecting, not paying attention General Public spectators and General aircraft pilots from our creations.
It (the Safety Code) is also the ONLY reason most states allow the flying of model rockets period. Live by the Code.. it keeps us able to fly at all.
 
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Mr Rocket

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From the NAR website.

Model Rocket Safety Code
Effective August 2012

1. Materials. I will use only lightweight, non-metal parts for the nose, body, and fins of my rocket.

From the NAR High Power Rocketry Safety Code:

2. Materials. I will use only lightweight materials such as paper, wood, rubber, plastic, fiberglass, or when necessary ductile metal, for the construction of my rocket.​

From the Tripoli website, a discussion of the use of metal parts


My personal take on all of this, and I am not a spokesman for any of these organizations, would be:

  1. At a NAR event this mesh would be against the safety code if it were used in a model rocket because it specifically states no metal parts in the nosecone.
  2. In a High Power Rocket, under NAR or Tripoli High Power Safety Codes it would also be a violation because it is not necessary for structural integrity and there are other materials that could be used in its place (although possibly more difficult for you to use)
 
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rstaff3

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Wel, that imterpretation would pretty much rule out most every dual deploy rocket, every fiberglass one with an aluminum tip, yadda yadda yadda.
 

dhbarr

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I personally wouldn't consider an expanded aluminum mesh sublayer a substantial metal part. As always, the RSO you want to fly with is the person representing the club from which you need acceptance.
 

Mr Rocket

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Wel, that imterpretation would pretty much rule out most every dual deploy rocket, every fiberglass one with an aluminum tip, yadda yadda yadda.
I dont think so. If the aluminum tip is needed on a mach+ rocket due to heat then it is allowed. If the all thread is needed for structural strength in the avionics bay then it is allowed.

Putting a metal tip on model rocket just because it looks cool is unnecessary and unsafe.
 

mrichhcirm

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No substantial parts means simply:
NO metal Nose cones, Air-frames, Fin Cans or Fins.
With all the other materials currently available any kind of Metal for these major parts is simply unnecessary and are DANGEROUS In all impulse Hobby Rocketry. . . .
The aluminum mesh in question is both lighter and more malleable than, say, the polystyrene walls of the typical blow-molded Estes nose cone. It will need balsa formers and stringers, or else a hard shell laid on top of it, to hold its shape. It is not heavy and unyielding as, say, galvanized steel hardware cloth. Therefore it is not substantial IMHO....It is an aid to the fabrication process rather than a superstructure.
 

Steve Shannon

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I think we have to consider the actual risk created (or not) by incorporating a thin layer of metal mesh. It's not going to make the nosecone penetrate more; stiffness or rigidity does not result; neither does it create a dense structure that would retain momentum like a solid piece of steel. It's more like using foil or wire screen.
If you want an official answer from Tripoli, post your question on the Tripoli Forum.
 

rstaff3

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I dont think so. If the aluminum tip is needed on a mach+ rocket due to heat then it is allowed. If the all thread is needed for structural strength in the avionics bay then it is allowed.

Putting a metal tip on model rocket just because it looks cool is unnecessary and unsafe.
I agree on the earlier statements but most of the aluminum tipped rockets just aren't needed and there are other alternatives to the allthread. It's all interpretation and common sense (sometimes).
 

rstaff3

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I think we have to consider the actual risk created (or not) by incorporating a thin layer of metal mesh. It's not going to make the nosecone penetrate more; stiffness or rigidity does not result; neither does it create a dense structure that would retain momentum like a solid piece of steel. It's more like using foil or wire screen.
If you want an official answer from Tripoli, post your question on the Tripoli Forum.
I can see the discussion regarding a modroc, but if Tripoli rejected thin mesh over balsa, then they'd have to be pretty darned hypocritical.

By all means, make sure that mesh is made from a malleable metal. :eyeroll:
 

mrichhcirm

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To clarify, we are talking about LPR, and since my club is an NAR chapter then those community standards apply.

My overall goal here is to try something new and interesting (like rockets that have some cross section other than round or square tubes) without creating a hazard.
 

rstaff3

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Thanks, that will focus the discussion. I guess I concede that this is probably not acceptable under the LPR code, even though I think the answer is pretty dumb in this case. I will not make any further suggestions as my nomex underwear is in the wash.
 

Steve Shannon

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I can see the discussion regarding a modroc, but if Tripoli rejected thin mesh over balsa, then they'd have to be pretty darned hypocritical.

By all means, make sure that mesh is made from a malleable metal. :eyeroll:
I'm pretty sure we would not reject it. I'm just saying that's the place to get an official answer.
I can definitely tell you this: I have no problem with it and I don't believe the other board members would either. .
 

Johnly

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Can't quite figure out why one would need to the metal mesh to the structure of a LPR air frame, but also don't see it as an automatic RSO DQ.
It doesn't increase the penetration capability beyond that of a fiberglass air frame.
There's a significant difference between a metal nosecone and metal containing nosecone in the text of the LPR safety code. If one really wanted to go off the deep end would a metal screw eye in a balsa nosecone or epoxy and lead shot in the nosecone be a DQ? I don't think that that is the intent of the cited clause.

John
 

rstaff3

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I'm pretty sure we would not reject it. I'm just saying that's the place to get an official answer.
I can definitely tell you this: I have no problem with it and I don't believe the other board members would either. .
Steve, sorry that my comment sounded kinda snotty. I am sure the BOD would be reasonable.
 

Steve Shannon

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Steve, sorry that my comment sounded kinda snotty. I am sure the BOD would be reasonable.
No problem. I agree; it would be ridiculous for us to reject a structure that used lightweight metal mesh as an armature for an unusual shape. And I've never seen a mesh that wasn't malleable! [emoji106]
 

Daddyisabar

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The idea is to allow me to sculpt shapes that don't have the usual rotational symmetry of your garden-variety nosecone. Picture an Apollo LEM or airplane-type nose with protruding domes, canopies, etc. Or other shapes that don't have a cylindrical cross section.

Or maybe I could coat the mesh with Bondo, plaster, etc. and create a mandrel that I could lay up the shape on with FG. That could work too, I guess.
Show us what you are building. If making the front end of an airplane like rocket (i.e. an AVRO Lancaster) you do not need light weight materials and you will quickly leave the realm of low power and go to at least mid power.
 

Daddyisabar

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No mesh needed. Just power and nose weight:

PA240021.JPGP1130086.jpgP3100165.jpgP3230176.jpgP4090189.jpgP4090191.jpgP7300272.jpgStuka 3.jpgStuka 4.jpgB 58 2.jpg

Light weight materials are a must from the nose cone down. Maybe useful in an Me 262 body. Would foam be better?

Check out the stick built models by John Boren (Jumpjet)

The NARAM winning LEM model I once saw in a box from Bruce M's estate was stick built.

Flying stuff like this and substantial metal parts are the least of your worries at the RSO table.
 

MClark

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There was a discussion at a BoD meeting at LDRS of what metals were acceptable in HPR. The term ductile is not a good property to use, the standard joke is "Can I use ductile iron for a nose cone?"
Most people would think aluminum is more ductile than chrome moly steel or titanium, but it is not. The TRA rules where changed to specifying aluminum or copper alloy, other metals would need BoD approval and would likely be limited to certain launch sites.
 
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