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PostPosted: 04 Oct 2009 08:54 pm 
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Joined: 03 Mar 2004 07:31 pm
Posts: 1021
The wing joiner of my Elita broke few months ago. After a lenghty repairing of the ship, its about time to make the joiner.

The joiner is 25mm in width, 15mm height and 160mm long each side. Two degrees of dihedal each side.

The mode is made from alu tubes :

Image

Four pieces of brass bar as spacers and put in place. PVA (mould release agent) already applied on all surface:

Image

Carbon tow (used 60 meters) cut to suitable lenght and wripping the spacers. The mould is ready to close:

Image

Mould closed with excessive force applied in order to squeese out the epoxy. Thereafter, put into vacumum bag. No air bubbles is allowed in the joiner:

Image

The mould was kept in warm box (at 50 C) overnight. After opened the mould, the joiner seems OK. The next thing is to pull out the spacers. The hole at the end is for easily access to a vice / clamp. Final step is to cut into suitable size :

Image

The finishing is good. Looks like a commercial produced. Total weight is 77 grams (well done) as I have used UHM carbon which is quite expensive :

Image

:lol: :lol:


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PostPosted: 04 Oct 2009 11:18 pm 
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Joined: 12 Jan 2005 12:20 pm
Posts: 1008
Location: Shatin (Tai Wai)
Excellent crafemanship :o

The brass rods can be used for extra ballast inside the new wing joiner :wink:

Next action item will be DS Elita again to > 300 km/h for stress test :idea:


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PostPosted: 05 Oct 2009 12:35 am 
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Joined: 26 Feb 2004 05:08 pm
Posts: 2941
Location: Hong Kong
:shock: 勁,不愧為滑翔機會技術主管!

Just want to ask: How do you decide how much carbon to use? By trial and error? Calculation?


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PostPosted: 05 Oct 2009 01:24 am 
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Joined: 26 Feb 2004 03:51 pm
Posts: 3624
Location: Hong Kong
有幾個問題想問:

1. Epoxy 乾左之後條 bar點樣脫出?

2. 你係唔係用左4條 bar?兩條 bar 在陣的中位置怎樣夾埋,如果有空間,D碳纖會積聚於此!


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PostPosted: 05 Oct 2009 07:11 pm 
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Joined: 03 Mar 2004 07:31 pm
Posts: 1021
:lol:

CM,

By estimation only.

:lol:

Stanley,

Are you asking me how to '脫 bra' ?
Every man should know it well !

OK, the brass bars were wrapped with a very thin plastic film with wax. After the epoxy set, pull them hard. Thats why there were holes at the end for making the job easiler.

Second, a piece of masking tape was put between two brass bar. With the tape and the wrapping, there would have no gap between. Hence, the carbon tow would not 積聚於此!

Regards,

Pong


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