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Old Apr 15, 2009, 09:44 PM
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Ezza's Avatar
Byron Bay, Australia
Joined Feb 2006
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Quote:
Originally Posted by Francesco
On a friend's Xplorer I noticed that the joiner boxes are significantly "deeper" (about 15 cm) than the joiners themselves (7 cm). Can you confirm this observation? Do you think that having that much empty space may result in a weak spot? I am asking this because two days ago I witnessed a structural failure upon launch in the joiner box of the center panel of my friend's Xplorer, and I am trying to trace down the cause.
TIA,
Francesco
Thanks Francesco,

I would like to hear comment on this as well.

Measured my dbox version. Centre panel joiner box, is 140mm deep. On the tip panels, the joiner boxs' are 115mm deep. The joiner only extends 75mm into each box? Anyone know if this creates a weak point?

You also have to be careful to get the centre of the joiner, lined up, whilst assembling or there could be alot of stress on the joiner box.

Eric
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Old Apr 15, 2009, 10:00 PM
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It's always a good idea to mark the top centerline of your joiners. I also put an arrow on the tip side of the joiner pointing towards the tip, and mark them left and right. Silver magic marker works good for this. Lastly, to avoid stressing the joiner box during assembly, always install the joiner into the tip first then into the center panel. On some planes it doesn't matter as much as others, but it makes a difference on the Xplorer!

Clay
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Old Apr 15, 2009, 10:03 PM
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Harbor City, CA
Joined Oct 2003
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Quote:
Originally Posted by SmokinJoe101
Target,

I will help you get on the TD fast track No need to learn the hard way,

I will share some of my secrets and tips, you open Friday?


sj

Yup!

T
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Old Apr 16, 2009, 02:21 AM
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Francesco's Avatar
United States, CA, Mountain View
Joined Apr 2001
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Quote:
Originally Posted by target
Was it a D box, or an all carbon Xplorer?
I can measure for you.

T
Hi target,
it was a D-box centerpanel.
Francesco
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Old Apr 16, 2009, 07:10 AM
Detail Freak
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Harbor City, CA
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Francesco-

Hello, and thanks.

While working on my center panel last night, I casually stuck a pencil in the joiner box, and it is in fact much longer than the joiner.
I don't know that this is a bad thing though; I would think that it would need to be a bit longer.

Target
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Last edited by target; Apr 16, 2009 at 07:16 AM.
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Old Apr 16, 2009, 07:15 AM
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United States, CA, Mountain View
Joined Apr 2001
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Quote:
Originally Posted by target
Francesco-

Hello, and thanks.

Whils working on my center panel last night, I casually stuck a pencil in the joiner box, and it is in fact much longer than the joiner.
I don't know that this is a bad thing though; I would think that it would need to be a bit longer.

Target
Thank you for trying, target. My concerns about the joiner box length is that there would be a strong discontinuity as for the ability to take bending load between the first 7 centimeters, the following 8 centimeters, and the remaining part of the wing, thus creating possible failure points.
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Old Apr 16, 2009, 09:59 AM
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Quote:
Originally Posted by target
Francesco-

Hello, and thanks.

While working on my center panel last night, I casually stuck a pencil in the joiner box, and it is in fact much longer than the joiner.
I don't know that this is a bad thing though; I would think that it would need to be a bit longer.

Target
Yes, it is a bad thing but easily corrected with longer joiners or fill the joiner box.

Just add this to the X mod list, BUT still shorter than the Supra's mod list.

sj
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Old Apr 16, 2009, 10:06 AM
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I suppose you could glue a wooden dowel in the center panel joiner box to take up the additional space - easy fix.

Clay
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Old Apr 16, 2009, 10:08 AM
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No it does not have to be a negative thing to have a longer joiner box. Some of the earlier days F3B models had full span joiner box for ballast.
Actually it would be a very good thing to have space for a little ballast in the joiner box. In turbulent conditions some models with light tips would like ballast out there.
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Old Apr 16, 2009, 10:12 AM
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Quote:
Originally Posted by jojoen
No it does not have to be a negative thing to have a longer joiner box. Some of the earlier days F3B models had full span joiner box for ballast.
Actually it would be a very good thing to have space for a little ballast in the joiner box. In turbulent conditions some models with light tips would like ballast out there.

JoJo.

Tell that to Francesco's Buddy

sj
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Old Apr 16, 2009, 11:54 AM
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Quote:
Originally Posted by SmokinJoe101
JoJo.

Tell that to Francesco's Buddy

sj
Off course there can be a problem on his model. Or maybe the failure came for another reason? There must be more to the story here.
If a wing fuse goes in two pieces on a landing is it a poor constructed fuse or a hard landing? You will have to see the landing to know or not?

I just say that a long joiner box does not mean a weak spot.
We should atleast learn how it was damaged and in what way.
Maybe the joiner box was not well wrapped or glued in the wing? One should be able to tell by looking or take it apart.
I would send it to the producer and tell what happened. then hope for a new piece or a good price on a new one.
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Old Apr 16, 2009, 04:00 PM
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United States, CA, Mountain View
Joined Apr 2001
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Quote:
Originally Posted by jojoen
Off course there can be a problem on his model. Or maybe the failure came for another reason? There must be more to the story here.
If a wing fuse goes in two pieces on a landing is it a poor constructed fuse or a hard landing? You will have to see the landing to know or not?

I just say that a long joiner box does not mean a weak spot.
We should atleast learn how it was damaged and in what way.
Maybe the joiner box was not well wrapped or glued in the wing? One should be able to tell by looking or take it apart.
I would send it to the producer and tell what happened. then hope for a new piece or a good price on a new one.
Thank you for the insight, Jo.
I'm pretty sure the producer will be able to sort out the matter and replace if applicable, I just wanted to ask the community to see if the "box length" matter was present in other models. It is also worth mentioning that I do not blame by any means this to be the cause of the mishap, I'm just curious and I'm investigating.
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Old Apr 16, 2009, 04:26 PM
Chris Lee
United States, MO, St. Louis
Joined Oct 2005
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Quote:
Maybe the joiner box was not well wrapped or glued in the wing?
I have seen the inside of two Xplorer joiner boxes. The joiner boxes (both center panel and tips) are composed of carbon tow wrapped around a joiner form. This box is then epoxied in between the carbon spar caps with end grain balsa continuing where the box ends. There is no wrapping material that ties the top and bottom spar caps together at any point along the length of the spar.

A picture can be seen here.

Chris
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Old Apr 16, 2009, 06:53 PM
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Sarasota, FL
Joined Jan 2006
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What is the consensus on this plane? Regular D-tube or Carbon wings? I just ordered an Xplorer with D-tube as I do not regularly fly competition and when I do I don't go for broke on the launches.

The club has several Shadows and everyone loves them.

Thanks

Phil
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Old Apr 16, 2009, 07:10 PM
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United States, CA, Midway City
Joined Dec 2003
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Quote:
Originally Posted by lineofsight
I have seen the inside of two Xplorer joiner boxes. The joiner boxes (both center panel and tips) are composed of carbon tow wrapped around a joiner form. This box is then epoxied in between the carbon spar caps with end grain balsa continuing where the box ends. There is no wrapping material that ties the top and bottom spar caps together at any point along the length of the spar.

A picture can be seen here.

Chris
From reading the description, there was a crash and repair of one of the tips joiner box previously, but the owner did not inspect or maybe did not see damage to the center panel's joiner box which now was stated as compromised.

I have both D-box's and think the strength is fine. I've launched off of mono on an FLS winch in 12MPH wind and though I was a little apprehensive the first time, I have no doubts that th Dbox X can handle it.

On a side note, I flew the X just this Tuesday in 20-25mph turbulent and very gusty wind with no ballast but was still able to penetrate, even if just barely. . Love my X!

T
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