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LPR/MPR - Durability of kraft white body tubes?

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LW Bercini

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Am I the only one having this problem?

Regardless of whether I use Titebond II or epoxy to surface mount my fins, I get much poorer joint strength using the kraft white tubes than I do with the "traditional" brown spiral-wound tubes.

It seems like I pop more fins on the builds where I used the white tubes, because layers of paper adhere to the fins, but peel away from the tube.

 

Micromeister

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I'm really not sure why your having trouble with the White Glassine wrapped body tubes.
Some people swear by sanding off the Glassine down to bare cardboard. I do NOT agree with this practice, however I do rough up the surface in the area where the fins are to be attached.
I've been using white finished tubes as long as they have been available, along with standard brown tubes for over 30years now with only an occasional broken fin landing on Concrete or Asphalt surfaces.

From your photo it does look like your using the epoxy rivet method of attachment but I only see a single line of rivet holes. You might want to try using dual line rivet holes alternating along the center fin alignment line. Not sure if that will help but it might.
Generally I use Elmer's yellow carpenters glue to tack the fins on, then a 1/2 fin thickness diameter epoxy rivet fillet to complete the attachment. I have 1983 and up Rockets with 20 to 70 flights without a single fin problem.

Have to admit I'm not a big fan of Titebond products. not sure if that could be part of your problem, Why not give Elmer's white glue or yellow carpenters glue a try. Using the double glue joint method either set up very quickly. It is my experience that both retain a bit of flexibility along with the 5 or 30 minute epoxy I use which is Devcon 5-min. or 2-ton. I have even older model rockets that are still flight-worthy with no fin or LL attachment failures.

PS: Not sure if you are aware that White glassine and old school clear glassine are actually the same chemically.
 
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LW Bercini

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I'm really not sure why your having trouble with the White Glassine wrapped body tubes.

<snip>

Have to admit I'm not a big fan of Titebond products. not sure if that could be part of your problem, .
1. As far as I can tell, there is no glassine on these tubes.

2. As I said, the problem seems independent of whether I use epoxy or Titebond. I still have models from the 1980s, built using Titebond II, that are still intact -BUT- all of these used the spiral wound brown cardboard tubes
 

Sooner Boomer

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Are you using "glue rivets" under the root of each fin? It looks like it. When using Titebond-type glues, did you use the double-glue method (rubbing a thin layer of glue into each surface and allowing it to dry before making the final glue bond)?

The only white paper tube that used surface-mount fins I can recall was in a Holverson Design rocket. It suffered a CATO and was cooked from the inside and delaminated completely. Seems like everything else (using white tube) used through-the-wall fins.
 

LW Bercini

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A When using Titebond-type glues, did you use the double-glue method (rubbing a thin layer of glue into each surface and allowing it to dry before making the final glue bond)?
I always use the double-glue method. If you were to examine the root of a detached fin, you would see there is a layer of the tube still attached to the fin. If I were to re-glue it, the next traumatic event (usually a fall off a table) would result in a new layer peeling off the tube and remaining attached to the fin.
 

LW Bercini

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As far as I can tell, the solution for me is to avoid these whit kraft tubes whenever possible. If not possible, then use a TTW attachment.
 

TheTellurian

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Those tubes are likely using a weaker glue to hold the wraps together if they use a glue at all. Some are held together by steam and/or compression only.


Richard
 
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