Fiberglassing

[Steven88]

Merry Christmas. I have built a few HPR kits in the past and modified a fiberglass kit I purchased used. They are large and fly fairly slow. I have a few questions about fiberglassing as I have never done that for possible future kits I may purchase.
How do know when it is necessary to fiberglass? Is it only when flying over Mach? Are the rules the same for fiberglassing with a paper tubes versus fiberglass? How do you know if glassing the fins only is enough or tubes need it as well? Thanks for the tips.

 

[rharshberger]

Glassing a FG tube is usually unnecessary nor recommended, tip to tip glassing of fins however is needed at certain points (mach 2ish iirc but it varies with fin shape and attachment). Glassing a cardboard airframe is mainly for toughness/road rash resistance and less for performance...though you can do it for performance. A glassed cardboard airframe CAN weigh less than a thin wall FG airframe of the same diameter, but it will not have the performance capabilities of the all FG airframe. I do most of my glassed Loc airframes simply to improve the toughness of the airframe (resistance to damage) not to push the airframe above mach, as such most of my airframes receive 2 wraps or so of 6oz FG cloth enough to toughen the tube but still keep it lighter than a all FG airframe and it allows a bit larger motor selection for a given diameter. Comparing the all FG to a glassed carboard/phenolic airframe is kind of apple to crab apples comparison (not as bad as apples to oranges but somewhere in the middle). IMO of course.

 

[cbrarick]

Here we go again.

Loc Vulconte CTI J600, 1150 mph. Well above mach
Not sure you can get more out of it then that, due to lack of bigger motors.....

Made with Tightbond and NO epoxy. NO fiberglass anything. It does have a horrible paint job - and is called "morning after bad thai food" thanks to the choices of colors my then 5 year old son made....

Glassing helps with toughness, not performance. It can help the rocket survive the car ride there (maybe) although mine bounces around the trailer all the time.

It's a myth that bare cardboard can't go above mach.

 

[Hobie1dog]

Fiberglassing is a huge messy PITA. a standard fiberglass tube is really tough and is all you need. But some people love spending the precious minutes of their remaining time on Earth building heavy thick walled Sonotube rockets that they feel is necessary to spend more money and time by adding another layer of a fiberglass cloth onto. Breathing in nasty resin fumes, and making a mess, and disposing of all the waste afterwards. Ending up with a rather coarse finish that requires more time and waste getting it ready for paint.
Disclosure: I use to work for Owens Corning Fiberglass at their Technical R&D Center.

 

[tfish]

Some people like to buy ready to fly or almost ready to fly rockets and or rocket parts..which is cool.
Other people like to scratch build and learn about building their own stuff. This could include..rocket propellant motor cases and parts, body tubes, nose cones and molds, altimeters and parachutes. I'm sure I'm leaving off 100 other things we can make.
NOT a pita to me! More like interesting. Exciting and challenging.









Tony

 

[rfjustin]

Some people like to buy ready to fly or almost ready to fly rockets and or rocket parts..which is cool.
Other people like to scratch build and learn about building their own stuff. This could include..rocket propellant motor cases and parts, body tubes, nose cones and molds, altimeters and parachutes. I'm sure I'm leaving off 100 other things we can make.
NOT a pita to me! More like interesting. Exciting and challenging.

Agreed sir. Any fiberglass or carbon work I have done I have really enjoyed. First couple attempts were a bit rocky, but have improved significantly over time. Like you to said, everyone takes in the hobby in their preferred area. For anyone wanting to get into fiberglass, build a test bed rocket like a 54mm LOC Pro Nuke Maxx and fiberglass the tubes and also put glass fin to fin on it. It is not needed, but the idea of a test bed rocket can put your nerves at ease and gain experience as you go. Rockets are cool, even the heavy fiberglass ones, rockets are cool, life is good, cheers!

 

[kenstarr]

I fiberglass for the enhanced performance in handling, transportation, and hard landings on the salt flats (may they ever rest in peace ) I've done glass and CF also because that was what I built the rocket from, no cardboard whatsoever, but a huge thing for me is simply the joy of mixing resins and turning some random cloth (fiberglass or carbon fiber) into something solid and durable. I'm not into polyester or vinylester resins on account of the fumes. I remember watching a really nice well made heavy duty carbon fiber rocket shred from a CTI N10,000.

 

[JohnCoker]

Not all cardboard is SonoTube and it's certainly possible to get a good result. However, I agree that fiberglassing isn't necessary most of the time. As rharshberger said, it's more about durability than in-flight stresses as many cardboard rockets have exceeded Mach 1.

 

[Steven88]

Some people like to buy ready to fly or almost ready to fly rockets and or rocket parts..which is cool.
Other people like to scratch build and learn about building their own stuff. This could include..rocket propellant motor cases and parts, body tubes, nose cones and molds, altimeters and parachutes. I'm sure I'm leaving off 100 other things we can make.
NOT a pita to me! More like interesting. Exciting and challenging.









Tony

Thanks for the videos

 

[Steven88]

But there is some risk of fin flutter and losing a fin flying beyond Mach 2 or so, correct, as stated in the second post, so tip to tip fin glassing would be recommended for that depending on the fin shape etc?

 

[rharshberger]

But there is some risk of fin flutter and losing a fin flying beyond Mach 2 or so, correct, as stated in the second post, so tip to tip fin glassing would be recommended for that depending on the fin shape etc?

There is always fin flutter, but the longer the span the more deviation and the faster the flight the faster the oscillations and at some point BOOOM! the fins are ripped apart or the airframe fails at the fins and the rocket is confetti!

 

[tfish]

Fiberglass ramblings to follow..
Pro tip..right off the bat,,don't forget to strengthen the couplers too!
when to glass cardboard rockets..when you're going to push them or when you want them to last longer.
My youngest son AJ..22 years ago..Estes Fat Boy..g10 fins, 2 layers of 6 oz on the BT and 2 layers inside the nose cone. Has flown 8 times.


54mm min dia..LOC tubing 2 layers of 6oz.. 20+ K flights..20 years ago..rocket still flyable


AT K1275


after about 20 flights..


When to do tip to tip or large fin fillets with rocket poxy or other fin filleting stuff.
I find that tip to tip is more durable for me..I built a couple of rockets with rocket poxy and needed to fix cracked fillets a few times. seems to be from fast or hard landings..I never had a flight mishap to see how they wold hold up ..

I have a bunch of .097 G10..I use it on all my rockets..for the most parts..on 3 and 4 inch rockets I use the tip (1/3) to tip92/3) to help beef up the .097 G10..by layering it in the needed area...near the root cord.
on my altitude rockets I like have fins with a span of 1.1 calibers....I feel that extra 0.1 span helps with flights over mach 2...and it helps in recovering from any in flight issues.

Here's a fiberglass rocket with 1/3 - 2/3 FG and a fin span of 1.1 calibers. It looses on side of the nozzles exit cone..


To me..Nike Smoke have the most prone to flutter fins around. Short root cord and long spans.

end of ramblings...

Tony

 

[IceLaunch]

In addition to fiberglass rockets, I'm building a Cozy MKIV 4-seater fiberglass aircraft. If you are interested in learning about working with fiberglass from the master (Burt Rutan), I recommend https://www.aircraftspruce.ca/catalog/bvpages/rutancomposites.php?clickkey=379165

 

[deandome]

I guess I don't really understand fin flutter and why it's ever necessary to tip to tip on any NON minimum diameter rocket. Cuz with any given design/motor combination (say, 4' with biggest 75mm motor, 5" or 6" with any 98mm, etc); can't you eliminate it thru basic engineering by using thicker G10 and or physical ways (on top of adhesives) to 'lock leading fin-root to motor mount?

By 'any', I mean I mean 3 or 4 fin designs; not Darkstars et al. And admittedly, I'm not into keeping stuff as light as humanly possible or altitude records. But is there any 75mm motor that will tear the fins off a properly/normally built Punisher? If you sand/grind/mill double-edged diamond profile fins out of 1/4" G10, can't you build a Nike Smoke that can take ANY MOTOR?

 

[DMehalko]

I glass for added durability, surface finishing, and of course feel better about putting more punishing motors into the build without fearing structural failures

Plus the sleeves offered from Soller Composites makes it SUPER easy IMO