Why Phenolic Tubing?

Why is phenolic tubing preferred for use in some applications amateur rockets?

I've seen that folks seem to prefer to use them as liners in hybrid rockets and then for exteriors of other rockets. What's the benefit of phenolic versus straight up paper tubing, fiberglass or carbon fiber?

Thanks for helping out with my newb question!

Cheap and heat resistance.

Sascha said:

Why is phenolic tubing preferred for use in some applications amateur rockets?

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Phenolic is superior to paper for airframes because it has a harder surface. This means that mating surfaces, such as couplers and tubes, won't wear out as fast and ends of tubes won't fray/fold. Also, phenolic is (more) water-resistant so you can wipe black powder residue off with a baby wipe. It's also about the same weight (lighter than equivalent strength paper tubes).

Note that there are various types of phenolic. The most commonly used material is wound paper as well, but the "phenolic" means impregnating the paper with a resin that creates a (more) solid composite. Aside from variations in the base material and resin, tubes can be heat-cured as well ("vulcanized phenolic", solid as "blue tube").

Ah, a chance to go into one of my phenolic tubing rants.

Ok, I'll restrain myself from ranting and go with some calm commentary instead-

I really don't like standard phenolic tubing. It's VERY brittle. I've had a few rockets that have had "less than optimal" landings and the phenolic tubing simply shattered in each occasion. These same type of landings have occurred with some of my other rockets - made from BlueTube, fibreglass, and even heavy paper - all of those survived just fine and/or were easily repaired. I've had phenolic motor mounts shatter on landings that really weren't all that hard. I even had a phenolic tube that was a tracker bay in a nose cone shatter on landing - again, not a particularly hard landing at that. That tubing never even took the direct impact, but it still broke.
Do NOT like phenolic tubing.

On a more positive note, I LOVE BlueTube. It's very similar to standard phenolics in terms of cost, weight, building/working qualities, etc. but it's TOUGH. It very easily handles those "less than optimal" landings, and bumps and grinds that are part of the rocketry game. Very good stuff.

My recommendation: if you are attracted to phenolic tubing, I say skip right over it and go with BlueTube. It's a drastically better option.

FWI,
s6

cwbullet said:

Cheap and heat resistance.

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I use it for motor mounts and that's it. Failed my first attempt at level 1 because of phenolic airframe shattered.

Welcome to the Forum Sascha.

bill2654 said:

I use it for motor mounts and that's it. Failed my first attempt at level 1 because of phenolic airframe shattered.

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This why I fiberglass it.

Wow, thanks guys for the quick answers and great run down of the pluses and minuses to Phenolic tubing! Very helpful. Thanks again!

cwbullet said:

This why I fiberglass it.

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I carbon wrapped my L3, still got a hairline crack on the top end when it fell over on landing.

Bluetube is my non-composite of choice. Strong, relatively cheap, and it's blue!

That being said I'm buying phenolic tubing and couplers for my 6" rocket motor :grin:

Using Phenolic tubing ,Blue Tube and fiberglass resins also have their health risks...check out the Saftey Data Sheets before using Please!

Just to muddy the waters a bit, I really want to be on Blue Tube's bandwagon. I have built one rocket with it and it was strong for sure but it warped like a banana. I had to put it in the trash. Ain't nobody got time for that.

ive had a Bull-puppy kit that on the 2cd flight the nose shattered the airframe. when I built a scratch-built rocket out of a chunk of 3 in that I had laying around I glassed that puppy and flew that rocket 30 = times on I-357 Thunders, I'll never buy plain phenolic again, and by the way that rocket I used panty-hose to glass it. if you look hard enough you can find my interview on a Rocketman video with a flight of it

grouch said:

Just to muddy the waters a bit, I really want to be on Blue Tube's bandwagon. I have built one rocket with it and it was strong for sure but it warped like a banana. I had to put it in the trash. Ain't nobody got time for that.

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How old was that rocket? I have spoken to the owner who produces Blue Tubes and he assured me that v2 isn't at all like v1. The BT produced in the last 1+ years is a new formula and doesn't warp unless you live in Seattle where you can get athlete's feet up to your armpits because it never stops raining.

I'd say it was about 2 years old or so. I ordered it for a planned project that fell through and kept it in my upstairs loft. The loft gets hot during the summer day when nobody is home. When I finally got around to using it I had to cut a little over 2' of it off to get to the straight section. I was not a happy camper. I ended up using the bent section as tube fins which worked out pretty good. I beat the crap out of that rocket and the tube never failed. The shock cord idea I came up with did though and the rocket fell from 3K without a chute, landed on it's side with only the smallest little ding on one of the tube fins. In the end I left it in the car and discovered BlueTube doesn't really like heat all that much, bowed up like a high school football player on steroids. I might try it again one day but I may try glassing phenolic first.

I'm putting together a 4" rocket using a Giant Leap 48" phenolic coupler to string together 5 cardboard chunks I've garnered over the years cored with another piece of phenolic, a 36" motortube. I bought 2 little bottles of Gorilla Glue to bond the inner to the outer. Worked on how to use the Gorilla Glue on couplers, no better way to do that. The glue foams and expands to fill the entire space then sets up, there are no gaps like epoxy or wood glue nor grabbing. You can't beat it

First motor planned for it is a J350 I've had since before the "Bad Times" but a J800 is in it's future with an extended front of cardboard over phenolic for DD

I am going to jump on the bandwagon for BlueTube. I have a few rockets now made from BlueTube 2.0 (which is the version, not the size). From 29mm through 4" Kraken. I have had a 3" BlueTube rocket fall on a shredded chute from 6000K + and it bounced when it hit the desert floor. Damage? Scratches and that's all. I have also had a BT2.0 4" Kraken deploy the drogue whilst going cruise missile mode, fast (400ft/sec estimate), all it did was unwrap 5" of the spiralling. EASY FIX!

EDIT

I have had the 3" BlueTube2.0 sat in a hot car, in the direct sun at out high desert site, and even had it rained on. Not one warp yet. This is version 2.0, not the original.

I like using phenolic, but use the flexible variety (party cured). Red Arrow is my favorite source, but Giant Leap has it as well though I have less experience with theirs. I always glass it. I have not have a tube shatter. I've had rockets take very hard hits and survive just fine. Hard hits on the edge can cause a bit of delamination like paper, but has not broken like PML fully cured phenolic - I cracked a tube of that once by just tipping it over on concrete. Only time I've had it break was a zipper on a 7.5" rocket, but then it didn't shatter, just tore into the tube for a few inches.

I like it for all the reasons John mentioned. Also, its cheaper than Blue Tube by a bunch.

I've built one 4" rocket from blue tube 2.0 to compare. Its also nice material to work with. I glassed it as well for toughness - may not be necessary, but I tend to abuse rockets. My only complaint is the motor tube. It has warped some making it tight to get some motors into it now - possibly due to the heat, possibly because the aeropack tailcone putting more force on it and the BT - the bottom of the BT is also has a very small bulge where the aeropack pushes on it.

What type of flight profile are you using the glassed flexible phenolic tube for Andy? Does it take high performance 38/54mm min diameter flights?

Jarrett, I havent done min dia with this construction technique - I have not built rockets that small with phenolic. With larger ones I get over mach with these occasionally, but not by tons. I really like big rockets most.