Anyone Tried FG Tubing from Rock West for HPR?

[mccordmw]

I'm really tempted to buy this 3" 7ft tubing since it's on clearance and super cheap.

https://www.rockwestcomposites.com/...earance-filament-wound-tubing/35410-fg-c74-25

Are the specs on this tubing suitable for use as an airframe for HPR? G12 airframes seem to have about 1/8" walls while this is about 1/12-1/13". Shoot, even thin-walled G12 looks like abou 0.098" - still thicker than this. Is this simply too thin? I'm not too knowledgeable about FG thickness vs strength requirements.

SPECS:
TUBE - FILAMENT WOUND - FIBERGLASS - SANDED & PAINTED - 3.125 X 3.275 X 74.25 INCH
$51.97
LG 74.25"
MATERIALS Fiberglass
PATTERN Filament Wound
INNER DIAMETER 3.000" +
OUTER DIAMETER 3.000" +
TUBE AND ROD FINISH Sanded Smooth Matte
WALL 0.075"
WALL THICKNESS 0.042" to 0.086"
WT. 3.5 lb

So...tempted...

 

[patelldp]

Remember when you subtract the ID from the OD, you need to divide by 2 to get the wall thickness.

 

[cavecentral]

Is wall thickness .75 or variable? .042-.084 seems like tolorances are poor. Guessing those are choices.

Sounds strong enough, finding a cone that fits is unknown.

 

[Bat-mite]

Also, you would need to cut custom CRs and bulkheads But Kevin nailed it -- finding or making a nose cone will be a real pain.

 

[dixontj93060]

2X variation in wall thickness seems like an awful lot. I wonder if that spec is "between pieces" rather than "within a piece." Also, since the wall is thin, you'd likely have to do some modification to any nosecone to get an seam that isn't "stepped." But personally, I think it is cheap enough that I'd risk buying a couple just to see (that is if I needed airframe material).

 

[dixontj93060]

Also, you would need to cut custom CRs and bulkheads But Kevin nailed it -- finding or making a nose cone will be a real pain.

I think the I.D. would be OK; whereas the O.D. is going to be on the narrow side affecting things like nosecone mating or if he was contemplating a fin can.

 

[dixontj93060]

Is wall thickness .75 or variable? .042-.084 seems like tolorances are poor. Guessing those are choices.

Sounds strong enough, finding a cone that fits is unknown.

I think the spec for wall thickness is: 0.075" nominal, -0.033"/+0.011". At least that's how I read it.

 

[mccordmw]

I can cut rings no problem. You're right. The nosecone might be a real pain. Hmm... The PNC-3.00 might fit inside, but I would expect some sanding of the airframe edge to get a smooth transition. I have a PNC-3.00, and it fits perfectly in a 3" mailing tube, but needs some airframe sanding for the OD.

Since this is filament wound, it is possible the wall thickness variance can be within the same tube. ID should be consistent since it's wound on a mandrel, but the outside might be wavy? That would be a real problem for me from an aesthetics standpoint.

 

[mccordmw]

Their tolerance datasheet makes it look more attractive.

https://www.rockwestcomposites.com/downloads/RWC-Stock-Tubing-Tolerance-Sheet-Rev-A.pdf

 

[flynfrog]

Its good stuff they make it down the street.

 

[patelldp]

A cone can be made by starting with a 4" FWFG cone and trimming it to the point where the base will match the OD of the tube.

I have 9x 48" lengths of 3.725" OD, 3.625" ID FWFG tubing if anyone is interested It's nice stuff, and I'll beat Rock West's pricing! I even have a cone that matches made via the above described method...

 

[bobkrech]

This tubing is listed as Tube - Filament Wound - Fiberglass - Sanded & Painted - 3.125 x 3.275 x 74.25 Inch which is the final dimensions after sanding.

The wall thickness for hobby thin-wall FG is ~0.050" and standard-wall FG is 0.062". This stuff is 0.075" wall so it is heavier than our standard stuff: 50% more than thin wall and 25% more than standard wall FG tubing. So your rocket will be heavier than our standard FG rockets and will require more TI to get the same performance.

This ID is 0.125" larger than our 3.000" inch ID standard for 3" airframe so you will have to build up the NC shoulder to make it tight, and the NC OD will be smaller than the airframe OD.

Other than these issues, it will be fine.

 

[Bat-mite]

That's a little bit like, "Other than that, Mrs. Lincoln, did you enjoy the play?" :wink:

 

[tomsteve]

peeked my interest, but seeing the shipping cost de peeked my interest.

 

[patelldp]

peeked my interest, but seeing the shipping cost de peeked my interest.

https://www.rocketryforum.com/showt...-from-Rock-West-for-HPR&p=1608937#post1608937

(Or look at post 11 above)

 

[dixontj93060]

Bob K. is right, I forgot to divide by two for wall thickness.

 

[3stoogesrocketry]

Is the OD a ground smooth surface ? The variation in spec tolerance could be a unground surface . I purchased a bunch of marine grade exhaust tubing , g12 , and it was a unground OD . Almost unusable if you plan to go fast , but made killer work horses .

Eric

 

[watermelonman]

One of my friends makes nose cones with layered fiberglass strips after making a plywood mold with shrinking diameter discs and sanding or using a lathe. He is not on this web site but I can put you in touch with him via email.