RC Slope Soaring in Hong Kong

A forum for rc sailplane pilots
It is currently Thu Mar 28, 2024 4:44 pm

All times are UTC + 8 hours




Post new topic Reply to topic  [ 17 posts ] 
Author Message
 Post subject: Canopy repair
PostPosted: Thu May 10, 2007 10:14 pm 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
What can be done when a canopy is broken due to old age ? AA glue seems not working well with that material :(
Image


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 12:12 am 
User avatar

Joined: Thu Feb 26, 2004 6:07 pm
Posts: 644
Location: Hong Kong
無得救 :!: 一喺用balsa做個mould,然後玩吸塑,或者買過個 :shock:


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 9:59 am 
User avatar

Joined: Thu Feb 26, 2004 5:08 pm
Posts: 3081
Location: Hong Kong
Hi Ah Mak,

Is it the Robbe ASH26 canopy? I have one and can make a mould for you.

Anyone know where can provide small volume vacuum forming service?


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 11:11 am 

Joined: Mon Aug 02, 2004 10:14 am
Posts: 621
Hi Mak and CM,
Would you please measure the dimension of the canopy. I have to see if my forming platform and oven are large enough.

Mak, there is a special glue for "canopy" or try contact cement (clear type). At least you can put the pieces together and then make a plug.
CA glue is brittle when cure. Canopy glue is flexible and is available at Waigo (hopefully).


CM, it is easier if your canopy is uncut.
For moulding the plug, please consider using yellow plaster.

Yeung


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 3:09 pm 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
CM Cheng wrote:
Hi Ah Mak,

Is it the Robbe ASH26 canopy? I have one and can make a mould for you.

Anyone know where can provide small volume vacuum forming service?


CM,
Yes, it's the Robbe ASH26 canopy.

How are you going to make the mould?
There are 2 methods in my mind. each have its disadvantage.

1. pour plaster in to the canopy.
Plaster is heavy which might break the original.

2. spray self expending foam in to the canopy.
This foam is light, hence may not fill up all spaces to form a good mould.


Yeung,
I didn't measure the size, but it should be around 1.5' x 9"


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 3:30 pm 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
I have an idea which might work without danger of breaking the original canopy due to weight.

We can put the canopy on water, and allow the canopy to sink into water, as we pour plaster into it.
We must keep the edge of the canopy above water surface. so that water outside the canopy will balance out the pressure inside the canopy.

There is another problem !
With that much plaster, the whole thing might get very hot and deform the canopy!
Yeung, does yellow plaster generate much heat ?


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 3:56 pm 

Joined: Mon Aug 02, 2004 10:14 am
Posts: 621
Mak,
You really do not fully fill the canopy with plaster, you can insert some foam in the center. (Less weigh and less cost). The plaster is thick enough that the foam will not float up.
Yellow plaster will not melt down you canopy. White plaster or fiberglassing with thick layer of epoxy will generate too much heat.

Your concern about overloading the canopy is correct. Big volume and mass of the plaster will push the canopy out and distort the shape. So it is necessary to support it outside before pouring in plaster. You can frame it with cardboard, white foam or some wood strip.

Putting the original canopy in water will make life harder. If the canopy is not rigid enough or supported, the heavy and dense plaster will still pushing out.

Neither the expanding foam method sounds good. The hot plastic sheet will be placed and pressed down to this plu and I don't think the foam one can hold it.

Yeung


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 4:14 pm 

Joined: Mon Aug 02, 2004 10:14 am
Posts: 621
Mak,
It is necessay to know the height of the canopy so as to estimate the size of the plastic sheet. It is not just the size of the base but also the material of the lateral surface.

It seems that my equipment cannot handle your project.
A large heater and a large forming platform are needed. For the platform, you can consider a drawer of a cabin or cupboard. But a large oven which can accomodate a big turkey is necessay. Mine is just a small one.

Is it possible to make it two portions?

Yeung


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 7:09 pm 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
Yeung wrote:
Mak,

It seems that my equipment cannot handle your project.
A large heater and a large forming platform are needed. For the platform, you can consider a drawer of a cabin or cupboard. But a large oven which can accomodate a big turkey is necessay. Mine is just a small one.

Is it possible to make it two portions?

Yeung


Hi Yeung,
I just measured the size.
It's 21" x 8" x 5"

Is it possible to hold a 2000W heater or a hair dryer above the setup to heat things up, while pulling vacuum with a vacuum pump ?


Top
 Profile  
 
 Post subject:
PostPosted: Fri May 11, 2007 10:44 pm 

Joined: Thu Sep 09, 2004 4:57 pm
Posts: 688
Don,t forget .I have a factory in china,we can do any type of canopy .any colour ,any thickness !!!!!!!!!!sent me your mold master !!!!


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jun 17, 2007 7:16 pm 
User avatar

Joined: Thu Feb 26, 2004 5:08 pm
Posts: 3081
Location: Hong Kong
原本用呢個方法減少石膏用量,但太杰失敗左,最後一層層塗上去。
Image
Image
Image
Image

阿麥,你桶石膏用晒嘞。 :)
Image


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jun 17, 2007 9:05 pm 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
CM,

Is that a solid plaster mould ? It looks real smooth :D
Image


Top
 Profile  
 
 Post subject:
PostPosted: Sun Jun 17, 2007 10:55 pm 

Joined: Thu Sep 09, 2004 4:57 pm
Posts: 688
Sent me as soon as possible !


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 18, 2007 7:44 pm 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
CM,

Did you sent the canopy to Ah Kin yet ?
If not, better take it with you to MOS.

I'm looking forward to fly the ASH26 together with yours. :D

BTW, start your ASH26 project early, and post the installation photos.
I need reference for my first scale glider project :o


Top
 Profile  
 
 Post subject:
PostPosted: Mon Jun 18, 2007 10:13 pm 
User avatar

Joined: Thu Feb 26, 2004 5:08 pm
Posts: 3081
Location: Hong Kong
Hi Mak,

The mould is not solid. Your plaster is not enough to fill it up :x

I will bring the mould to MOS tomorrow. It is very heavy, I think it is over 8Kg.


Top
 Profile  
 
 Post subject:
PostPosted: Tue Jun 19, 2007 1:45 am 
User avatar

Joined: Thu Feb 26, 2004 7:54 pm
Posts: 1660
Location: Tai Po, HK
CM Cheng wrote:
Hi Mak,

The mould is not solid. Your plaster is not enough to fill it up :x

I will bring the mould to MOS tomorrow. It is very heavy, I think it is over 8Kg.


What! It's not finished ?
Well, I have more plaster.
How much plaster should I bring ?


Top
 Profile  
 
 Post subject:
PostPosted: Wed Jun 20, 2007 12:36 am 

Joined: Thu Sep 09, 2004 4:57 pm
Posts: 688
埃!!!!!!!!!!!!!有D後侮,咁重...唔係..應該係咁XYZ###重,點囉反大陸,真大濟!!!!!!要用老土手拉車....(門+小)!!!!!!!!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 17 posts ] 

All times are UTC + 8 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron

RASAIL Home

WindGURU at Ma On Shan, Clearwater Bay and Fei Ngo Shan

Powered by phpBB® Forum Software © phpBB Group