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Back_at_it

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Nothing really bonds to glassine. I run into this all the time when doing my restorations. 9 times out of 10 the fins will simply pop right off the tube with all of the glue attached to the fin itself. Any remaining glue on the tube can typical he be pulled off with the fingernail living a pristine body tube.

I typically cut or sand an 1/8 to 1/4 inch outside the fin for the fillets.
 
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BABAR

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Should the glassine be lightly sanded before priming, for better paint adhesion?
 

Back_at_it

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Should the glassine be lightly sanded before priming, for better paint adhesion?
It wouldn't hurt anything. I've only had a couple of instances where paint has peeled up and that was only when peeling tape for multi colored paint jobs. This was back before I learned to use Tamiya and blue painters tape.

If you sand the tube you will need to do at least two coats of primer as there will be little fuzzy strands that popup with the first coat. These will needed to be sanded and a second coat applied.
 

neil_w

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Should the glassine be lightly sanded before priming, for better paint adhesion?
I have certainly never done this. Theoretically, isn't this the actual job of the primer? Primer peeling off a body tube is not something I've ever experienced.
 

Nytrunner

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What the heck is “% wood failure”?
It means the wood itself failed around the joint instead of the glue (notice the heated glue is 0% wood failure)

Looking at the plyywood mid-power rockets, a purely quick-n-thick fillet may fail in teh glue itself and leave more restorable parts whereas TBII may lead to more tube/fin breakage on a bad day.

But for balsa (papered or no) either one is fine. I just like a thin seam/fillet of TBII first because it locks things in place for the Q&T fillets
 

BABAR

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I have certainly never done this. Theoretically, isn't this the actual job of the primer? Primer peeling off a body tube is not something I've ever experienced.
Helpful. Thanks!
 

TALON

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I have been a "BAR" for over 8 years. I have incorporated just about everything mentioned here plus some. I have used cardboard gussets and chute buckets & anti zipper harness! I will over design for G forces more than longevity. The shock cord is the failure that bites me the most often. So I have switched to kevlar and stainless steel cable to solve that problem. I had my 1st BAR rocket land in a rock pile and get dragged across it by the wind in the chute! Did wonders for the balsa fins!:( I haven't had a air frame last more than 9 flights. I do notice that the paint bubbles from the heat and the spirals that I labored to fill start showing up from G force stress. Which leads to another topic, "The Finish"! I paper fins for the finish just as much for strength. I still try to fill the spirals as best as possible with different techniques (depending on the rocket), and try to get the best finish. But now I don't sweat it and spend as much time as I use to. And I don't agonize over paint bubbling and other dings and wearing from flights like I use to. When an air frame is showing its age and air worthiness is near its end, I will make it a hanger queen.
 

rklapp

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What the heck is “% wood failure”?

who puts their rockets in the bun warmer overnite?

does PSI strength account for the much thicker fillet?

as opposed to maple, something tells me that 3000psi exceeds the strength of balsa and cardboard, so anything over that seems like overkill.

back to original question, @neil_w (or any others with experience), does the addition of a small TB2 (or other classic wood glue) demonstably (meaning “in flight or recovery or storage”) improve fin retention?
Sorry, just trying to give some information I found.
 

jeffgeraci

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Lots of good stuff already posted.

The following applies to low power rockets, maybe to mid power. Being L-0, I know nada about high power construction.

Some of this depends on your goals for your rockets.

If you want beautiful showpiece Rockets, fly them once on a calm day with a large chute in a big field and then relegate them to display/“Hanger Queen” status. Beware even one flight can result in catastrophe. Classic and tragic example is here


Absolutely unique and beautiful design and finish, with an unfortunate maiden (and only) flight

@jeffgeraci

(Note: if you want it to stay pretty, don’t tempt fate by giving it a name like “Suicide King.”)

Even with the best of circumstances, few if any rockets maintain their “show room” looks for more than a few, say five, flights. So “building to last” and “building for looks” are not often complimentary goals.

With great and certainly due respect to @rklapp , who makes and flies beautiful rockets, for low power balsa to cardboard or paper joints, epoxy is overkill. MAKE SURE YOU SAND OFF THE GLASSINE OUTER LAYER OF THE BODY TUBE. Once you do that, wood glue for balsa to cardboard or paper is structurally just as strong, lighter, and smells better. Epoxy is needed if you are attaching plastic or fiberglass, but not wood and paper and cardboard.

If your design allows for forward swept fins (which IMHO look cool regardless), your rocket’s first interaction with terra all too firms (and sometime cementa or asphalta or playa) will be the motor casing or motor hook, either of which generally handle the impact better than the fin tips of the typical Rear swept fins of the quintessential Alpha. If stability allows and you can place your fins a bit forward of the rear edge of the tube (certainly do-able for long skinny rockets) so much the better.

Papering fins, especially with white glue instead of adhesive paper, adds a lot of strength, although many will say even adhesive paper helps.

Nobody has mentioned reliable recovery yet. Lawn darts tend to lose their showroom looks quickly and are frowned upon by most RSOs. Make sure your wadding and chute and streamer are packed loosely enough that you could literally blow them out with a puff of your breath, and the nose cone isn’t too tight. Estes Cosmic Cobra is a Great example of trying to fit too much into too little a space (interestingly the HeliCat is almost the identical rocket, just made a few inches longer, and is a dream to pack and fly.)

Avoid flying on windy days, rockets tend to either weathercock and disappear upwind or drift away and disappear DOWN wind. Putting your name and phone number somewhere on the rocket may help you in getting it back, but may get you in trouble if it drops into, let’s call it “unfriendly “ territory.

Even Kevlar shock cords can eventually burn through and break. Here’s @hcmbanjo ‘s article on a set up that allows you to check and if needed place them.


Best of luck!
I haven’t logged in for several years now, and I came to find your post from last month, how cool! I’m not forgotten, I love it! Thank you BAR
 

icyclops

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Fins are the weakest link.....paper your fins with card stock to increase their strength. This simple lamination technique using thick card stock and 3M Spraymount 77 on your balsa is easier than wood seal and sanding....Also, make nice and even fillets and paint primer, then paint using a good enamel.....besides the top body tube, fins take the most punishment in LP landings and lift-off.....
 

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