Today's Message Index:
----------------------
1. 01:50 AM - post curing (Graham Singleton)
2. 02:50 AM - Re: post curing (Gerry Holland)
3. 02:04 PM - Re: How did you Post Cure? (Rowland & Wilma Carson)
4. 03:03 PM - Re: post curing (Charlie Laverty)
5. 06:28 PM - Facets/Parrallel Fuel/Money/etc. (Tony Renshaw)
6. 06:37 PM - Post curing etc etc. (Tony Renshaw)
Message 1
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--> Europa-List message posted by: Graham Singleton <graham@gflight.f9.co.uk>
At 23:56 17/06/2003 -0700, you wrote:
> > Well I have this theory that the roof of my house will be an excellent
>post
> > curing oven in summer. The important aspects of postcuring is the ramping
> > up and down of the temperature, and if it really important to some to know
> > why,
Tony,
The resin might go real soft if you ramp up quickly then warp under its own
weight. Especially if post cure is done early on.
There's one other important thing, trailing edges. I would recommend
clipping all trailing edges to straight aluminium extrusions, spring clips
every 6 inches, to keep them straight. Not important aerodynamically but a
wavy TE looks awful
Graham
---
Message 2
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--> Europa-List message posted by: Gerry Holland <gnholland@onetel.com>
> Tony,
> The resin might go real soft if you ramp up quickly then warp under its own
> weight.
It's also worth keeping an eye on the items being cured at top of
Temperature 'range' if possible. Sometimes 'hotspot' areas form even when
air seems to be circulating well. Often the circulation is shielded by the
conflicting heap of bits for curing so ensure good spacing and no direct
radiation from heat source.
I unfortunately learnt a harder way. My Starboard Aileron had many degrees
of 'washout' as well as a radical new shape caused by a hotspot from
circulation airflow blocked. In fact the outboard 12" sort of exploded,
bursting out the end lay-up and deforming foam core and surface lay-up.
Fortunately my Inspector had many years of composite production and help me
rebuild it back to normal shaping and strength. Just a warning to be
vigilant but also a reassurance that this is great material to mend!
Regards
Gerry
Gerry Holland
Europa 384
G-FIZY
+44 7808 402404
gnholland@onetel.com
Message 3
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| Subject: | Re: How did you Post Cure? |
--> Europa-List message posted by: Rowland & Wilma Carson <rowil@clara.net>
At 12:17 -0400 on 16-06-03, John & Amy Eckel wrote:
>I take it from the replies so far that there is no danger of
>softening and warping the tailplane, rudder, flaps and ailerons
>at a temperature of 55C
John - it's probably NOT a good idea to take your parts straight up
to the final post-cure temperature. As I understand the post-cure
process, the cured layup starts with a fairly low Glass Transistion
Temperature (Tg) - that is the temperature at which it starts to go
wobbly. The ideal is to take it up to just below the initial Tg and
hold it there for a while. This heat-soak will raise the Tg, so you
can then increase the temperature again to just below the new Tg and
hold it again. You may have to repeat this more than once to get to
the final post-cure temp. The professional glider builders &
repairers, such as my inspector, have post-curing ovens with
controlled temparature ramping, and I plan to use his facilities for
all my foam-cored bits at once.
Another important consideration is that the foam core will melt
before you reach the highest possible post-cure temperature for the
(Ampreg 20) epoxy resin. So, don't just go by the resin
manufacturer's numbers (he doesn't know what other materials you
might be using), stick to what the foam can stand.
>Therefore no special support is needed.
I'd prefer not to risk the bits unsupported. My plan is to lightly
but firmly clamp each trailing edge between a couple of ali angle
pieces. They can then be suspended on the protruding ends of the ali
and hang vertically downwards, minimising the likelihood of unwanted
stresses.
regards
Rowland
--
| PFA 16532 EAA 168386 Young Eagles Flight Leader 017623
| 560 hours building Europa #435 G-ROWI e-mail <rowil@clara.net>
Message 4
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--> Europa-List message posted by: "Charlie Laverty" <bb@baliscate.freeserve.co.uk>
Hi Graham
Found missing organizers in bottom drawer of filing
cabinet, silly me, obvious really.
Best
wishes
Chaz.
Gillian and Charlie
Baliscate Guest House
Tobermory
Isle of Mull PA75 6QA
Tel 44( 0)1688 302048
Fax 44())1688 302666
www.baliscate.com
----- Original Message -----
From: "Graham Singleton" <graham@gflight.f9.co.uk>
Subject: Europa-List: post curing
> --> Europa-List message posted by: Graham Singleton
<graham@gflight.f9.co.uk>
>
> At 23:56 17/06/2003 -0700, you wrote:
> > > Well I have this theory that the roof of my house will be an excellent
> >post
> > > curing oven in summer. The important aspects of postcuring is the
ramping
> > > up and down of the temperature, and if it really important to some to
know
> > > why,
> Tony,
> The resin might go real soft if you ramp up quickly then warp under its
own
> weight. Especially if post cure is done early on.
> There's one other important thing, trailing edges. I would recommend
> clipping all trailing edges to straight aluminium extrusions, spring clips
> every 6 inches, to keep them straight. Not important aerodynamically but a
> wavy TE looks awful
> Graham
>
>
> ---
>
>
Message 5
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| Subject: | Facets/Parrallel Fuel/Money/etc. |
--> Europa-List message posted by: Tony Renshaw <tonyrenshaw@optusnet.com.au>
Graham,
Need that account no etc please as between me and Kingsley, I keep forgetting.
I want to get that money to you, so I better do it soon. Any luck with Andair
getting that new element??
Onto a 912S question. Do you like the way Nigel Charles has set up his fuel
system, the parrallel one, with no mechanical fuel pump, only 2 electric
Facets. I will include a picture. I read your statement below regarding the
inability of the Facets to provide adaquate flow rates to keep the fuel
pressure up, and keep the fuel in the return line circulating to avoid fuel
temperature buildup and subsequent vapourlock. Well with this setup there is no
return line, as he uses a pressure regulator. I think it actually sounds like
quite a good system, as it allows the full use of the fuel on the main side
with an automatic cutover to the reserve side when it expires. Mal and others
switch over to the reserve often when there is a considerable volume and
therefore endurance remaining. I want to be able to use it all, and if I stuff
up, or if the main side stuffs up, I don't want any switching, only flying and
let the engine look after itself, giving me a light or audible to highlight
what has just happened, rather than the silence that demands that "I do
something, as well as fly". I'd be interested in a penny for your thoughts.
Reg
Tony R.
At 10:20 AM 3/31/2003 +0100, you wrote:
>--> Europa-List message posted by: Graham Singleton <graham@gflight.f9.co.uk>
>
>At 23:56 30/03/2003 -0800, you wrote:
>>Gidday,
>>I have been following this thread for a while, because I started it. I am
>>surprised there isn't anything definitive, but I appreciate there is a
>>difference between ID and OD. I do however "not" have my head around why you
>>would need a restrictor in any fuel return line, irrespective of engine
type?
>
>The 914 is different, it uses rotary fuel pumps which delivery far more
>fuel than the engine requires. This is the reason the 914 needs a bigger
>return pipe dia than the 912s. 912s have a mechanical pump,
>displacement dependant on engine rpm so delivery is much more limited.
>Excessive return flow would cause reduced fuel pressure, which might not be
>enough to avoid fuel starvation. The Facet electric auxiliary pump also has
>limited displacement and won't give enough pressure to compensate.
>Incidentally, the limited displacement/flow rate also makes the engine more
>susceptible to vapour locking because the pumps have no way of catching up
>the deficit caused by the vapour. Hence the importance of the return pipe,
>it bipasses the vapour quickly and gets cool fuel to the pump. The pump
>absorbs heat from the gearbox, which is heated by engine oil.
>BTW there is no such thing as a daft question. How else can one learn?
>Graham
>
>
>---
>
>
Message 6
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| Subject: | Post curing etc etc. |
--> Europa-List message posted by: Tony Renshaw <tonyrenshaw@optusnet.com.au>
Thanks Graham for the advice. What are you up to??
Reg
Tony Renshaw
At 09:46 AM 6/18/2003 +0100, you wrote:
>--> Europa-List message posted by: Graham Singleton <graham@gflight.f9.co.uk>
>
> At 23:56 17/06/2003 -0700, you wrote:
>> > Well I have this theory that the roof of my house will be an excellent
>>post
>> > curing oven in summer. The important aspects of postcuring is the ramping
>> > up and down of the temperature, and if it really important to some to know
>> > why,
> Tony,
>The resin might go real soft if you ramp up quickly then warp under its own
>weight. Especially if post cure is done early on.
>There's one other important thing, trailing edges. I would recommend
>clipping all trailing edges to straight aluminium extrusions, spring clips
>every 6 inches, to keep them straight. Not important aerodynamically but a
>wavy TE looks awful
>Graham
>
>
>---
>
>
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