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stevenwpitt(at)me.com Guest
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Posted: Thu Sep 03, 2020 5:42 am Post subject: Airbox for 912S |
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I have had to repair my airbox as it split under the clamp.
Can anyone tell me how critical the airflow into the carburettors via the box is? Do I need to ensure a smooth and equal airflow?
I suspect not as the quality of the airbox is somewhat rudimentary.
For information I made up some ‘bid' tube and epoxied it into the existing airflow tube. I have tried to make the entrance a smooth as possible.
Thank you.
Steve Pitt
G-SMDH
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Rocketman
Joined: 07 Sep 2010 Posts: 87 Location: USA, Earth
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Posted: Thu Sep 03, 2020 6:31 am Post subject: Airbox for 912S |
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Steve, you should be fine as long as the internal diameter of the tube
is equal to or greater than the internal diameter of the carb opening.
Jeff
"I believe that forgiving them is God's function. Our job is to arrange
the meeting."
-Gen. Norman Schwarzkopf
On 9/3/2020 8:40 AM, Steven Pitt wrote:
Quote: |
I have had to repair my airbox as it split under the clamp.
Can anyone tell me how critical the airflow into the carburettors via the box is? Do I need to ensure a smooth and equal airflow?
I suspect not as the quality of the airbox is somewhat rudimentary.
For information I made up some ‘bid' tube and epoxied it into the existing airflow tube. I have tried to make the entrance a smooth as possible.
Thank you.
Steve Pitt
G-SMDH
|
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dpark748(at)me.com Guest
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Posted: Thu Sep 03, 2020 6:47 am Post subject: Airbox for 912S |
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When I had a airbox on initial build I bonded alloy tupe in to exits to strengthen them.
Dave Park
Quote: | On 3 Sep 2020, at 15:37, Jeff B <topglock(at)cox.net> wrote:

Steve, you should be fine as long as the internal diameter of the tube is equal to or greater than the internal diameter of the carb opening.
Jeff
"I believe that forgiving them is God's function. Our job is to arrange the meeting."
-Gen. Norman Schwarzkopf
> On 9/3/2020 8:40 AM, Steven Pitt wrote:
>
> I have had to repair my airbox as it split under the clamp.
> Can anyone tell me how critical the airflow into the carburettors via the box is? Do I need to ensure a smooth and equal airflow?
> I suspect not as the quality of the airbox is somewhat rudimentary.
> For information I made up some ‘bid' tube and epoxied it into the existing airflow tube. I have tried to make the entrance a smooth as possible.
> Thank you.
> Steve Pitt
> G-SMDH
|
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Duncan McFadyean
Joined: 18 Jan 2011 Posts: 220
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Posted: Thu Sep 03, 2020 8:39 am Post subject: Airbox for 912S |
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Steve,
The air entry to the carbs is quite critical and should ideally be smooth and tapering inwards from a larger diameter, which the Europa airbox more or less achieves. Generally a 2 degree inward taper will help to preserve lamina flow in the runner, as is often seen on the runners of injected engines.
This is further evidenced by the adverse impact on carburation that sharply curved SCAT tube and/or long parallel-sided runners has, such as on some Jabiru and VW installations.
Duncan McF.
Quote: | On 03 September 2020 at 15:30 Jeff B <topglock(at)cox.net> wrote:
Steve, you should be fine as long as the internal diameter of the tube
is equal to or greater than the internal diameter of the carb opening.
Jeff
"I believe that forgiving them is God's function. Our job is to arrange
the meeting."
-Gen. Norman Schwarzkopf
On 9/3/2020 8:40 AM, Steven Pitt wrote:
>
>
> I have had to repair my airbox as it split under the clamp.
> Can anyone tell me how critical the airflow into the carburettors via the box is? Do I need to ensure a smooth and equal airflow?
>
> I suspect not as the quality of the airbox is somewhat rudimentary.
>
> For information I made up some ‘bid' tube and epoxied it into the existing airflow tube. I have tried to make the entrance a smooth as possible.
>
> Thank you.
> Steve Pitt
> G-SMDH
>
>
>
|
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stevenwpitt(at)me.com Guest
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Posted: Sat Sep 05, 2020 7:03 am Post subject: Airbox for 912S |
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Now I have a dilemma. I have measured the diameter of the inner carburettor at 45mm. The airbox outer tube is 48/49mm - the inner diameter 39 and 42mm (these measurements after my fix - several layers of bid to strengthen the orifices after they collapsed under the tightness of the worm driven band).
I have never had a problem with the carburettors and never given any thought to a mismatch between the two diameters. I was always aware the the box was poorly finished and the air intakes were easy to crush, but with the bolt holding the box to the engine frame it had never departed giving me an inflight issue.
It is also notable that the two orifices were not the same size even before the collapse.
The only way I can see to equalise the two is to rebuild the airbox as per Dave Ps suggestion - cut the ends off - find an aluminium tube with inside diameter of 45mm and bond that in with bid. Anyone got any tube to that size?
Anyone else wishing to add any advice before I carve the boxes up. Also what is the airbox made from? It looks like chopped strand mat fibreglass.
Regards
Steve
G-SMDH
Quote: | On 3 Sep 2020, at 15:45, david park <dpark748(at)me.com> wrote:
When I had a airbox on initial build I bonded alloy tupe in to exits to strengthen them.
Dave Park
> On 3 Sep 2020, at 15:37, Jeff B <topglock(at)cox.net> wrote:
>
> 
>
> Steve, you should be fine as long as the internal diameter of the tube is equal to or greater than the internal diameter of the carb opening.
>
> Jeff
>
> "I believe that forgiving them is God's function. Our job is to arrange the meeting."
>
> -Gen. Norman Schwarzkopf
>
>> On 9/3/2020 8:40 AM, Steven Pitt wrote:
>>
>> I have had to repair my airbox as it split under the clamp.
>> Can anyone tell me how critical the airflow into the carburettors via the box is? Do I need to ensure a smooth and equal airflow?
>> I suspect not as the quality of the airbox is somewhat rudimentary.
>> For information I made up some ‘bid' tube and epoxied it into the existing airflow tube. I have tried to make the entrance a smooth as possible.
>> Thank you.
>> Steve Pitt
>> G-SMDH
>
>
>
|
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budyerly@msn.com
Joined: 05 Oct 2019 Posts: 288 Location: Florida USA
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Posted: Sat Sep 05, 2020 4:32 pm Post subject: Airbox for 912S |
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Steve,
The bing 64 has a 50mm OD inlet for the filter or airbox attachment. The bore is nominally 36mm.
The airbox (aka really cheap polyester chop and glass bit from Europa) have ends that attach to the carb are 50 mm tapering up 52 mm ish. The chop on some of these is so bad I had to reinforce it for the pop rivets on the nutplate it shattered so bad.
Jeff Roberts was the first I had seen modify his airbox due to cracking. It appeared he used a piece of two inch aluminum tubing and slid it into the well ground out holes in his airbox and aligned the tubes with his carbs and allowed the floxed tubes to cure, then wrapped the glass around the tube outside the rubber tube to final bond the outside of his tubing.
I copied Jeff’s later on using the 1 7/8 inch aluminum tube left over from the main pitch rod. I ground out the cracked airbox and inserted the 1 7/8 (47.6 mm) tube with flox and Redux (any epoxy will do) and then wrapped layers of bid around until I was about 50 mm or 1 15/16 inches diameter. Then shaped to get an easy fit of my two inch rubber hose. I was OK with this method since the connecting hose allowed the two inlets on the bing carb inlet sufficient clean air for normal operation. On a later aircraft I used 2 inch tube. The hose clamp clearly compressed the hose more on the carb side than on the inlet box with the two inch tube.
Epoxy sticks to just about anything but oil and grease so it will make a good repair bond to the clean and roughed up polyester without a problem of bonding. Remember to rough up the aluminum as usual also.
So you have two methods, either an innie or outie method.
Note: The airbox does not have to be really smooth on the inside. It is a plenum not a tuned inlet. The bing carb sucks air rather than ram air entering the carb on the 912S. The transition humps and bumps should be minimized but just make both ends about the same and all will be fine. Remember, the bing has an inlet on the inside above and below the bore so make sure they can get reasonably clear air...
Of course Rotax wants you to buy their $1000 intake plenum. The only problem is it tends to lack support and since it hangs on the carb, it cracks those expensive 43mm rubber carb manifold to carb flange. Support the inlet plenum, that supports the carb and those rubber carb flange adapters last almost forever.
Just my opinion,
Best Regards to Mary also,
Bud Yerly
Best Regards,
Bud Yerly
Sent from Mail for Windows 10
From: Steven Pitt (stevenwpitt(at)me.com)
Sent: Saturday, September 5, 2020 11:09 AM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Europa-List: Airbox for 912S
--> Europa-List message posted by: Steven Pitt <stevenwpitt(at)me.com>
Now I have a dilemma. I have measured the diameter of the inner carburettor at 45mm. The airbox outer tube is 48/49mm - the inner diameter 39 and 42mm (these measurements after my fix - several layers of bid to strengthen the orifices after they collapsed under the tightness of the worm driven band).
I have never had a problem with the carburettors and never given any thought to a mismatch between the two diameters. I was always aware the the box was poorly finished and the air intakes were easy to crush, but with the bolt holding the box to the engine frame it had never departed giving me an inflight issue.
It is also notable that the two orifices were not the same size even before the collapse.
The only way I can see to equalise the two is to rebuild the airbox as per Dave Ps suggestion - cut the ends off - find an aluminium tube with inside diameter of 45mm and bond that in with bid. Anyone got any tube to that size?
Anyone else wishing to add any advice before I carve the boxes up. Also what is the airbox made from? It looks like chopped strand mat fibreglass.
Regards
Steve
G-SMDH
> On 3 Sep 2020, at 15:45, david park <dpark748(at)me.com> wrote:
>
> --> Europa-List message posted by: david park <dpark748(at)me.com>
>
> When I had a airbox on initial build I bonded alloy tupe in to exits to strengthen them.
>
> Dave Park
>
>
>> On 3 Sep 2020, at 15:37, Jeff B <topglock(at)cox.net> wrote:
>>
>> --> Europa-List message posted by: Jeff B <topglock(at)cox.net>
>>
>> Steve, you should be fine as long as the internal diameter of the tube is equal to or greater than the internal diameter of the carb opening.
>>
>> Jeff
>>
>> "I believe that forgiving them is God's function. Our job is to arrange the meeting."
>>
>> -Gen. Norman Schwarzkopf
>>
>>> On 9/3/2020 8:40 AM, Steven Pitt wrote:
>>> --> Europa-List message posted by: Steven Pitt <stevenwpitt(at)me.com>
>>> I have had to repair my airbox as it split under the clamp.
>>> Can anyone tell me how critical the airflow into the carburettors via the box is? Do I need to ensure a smooth and equal airflow?
>>> I suspect not as the quality of the airbox is somewhat rudimentary.
>>> For information I made up some ‘bid' tube and epoxied it into the existing airflow tube. I have tried to make the entrance a smooth as possible.
>>> Thank you.
>>> Steve Pitt
>>> G-SMDH
>>
>>
>>
>
>
>
>
| - The Matronics Europa-List Email Forum - | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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budyerly@msn.com
Joined: 05 Oct 2019 Posts: 288 Location: Florida USA
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Posted: Sun Sep 06, 2020 5:58 am Post subject: Re: Airbox for 912S |
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Steve,
The bing 64 has a 50mm OD inlet for the filter or airbox attachment. The bore is nominally 36mm.
The airbox (aka really cheap polyester chop and glass bit from Europa) have ends that attach to the carb are 50 mm tapering up 52 mm ish. The chop on some of these is so bad I had to reinforce it for the pop rivets on the nutplate it shattered so bad.
Jeff Roberts was the first I had seen modify his airbox due to cracking. It appeared he used a piece of two inch aluminum tubing and slid it into the well ground out holes in his airbox and aligned the tubes with his carbs and allowed the floxed tubes to cure, then wrapped the glass around the tube outside the rubber tube to final bond the outside of his tubing.
I copied Jeff’s later on using the 1 7/8 inch aluminum tube left over from the main pitch rod. I ground out the cracked airbox and inserted the 1 7/8 (47.6 mm) tube with flox and Redux (any epoxy will do) and then wrapped layers of bid around until I was about 50 mm or 1 15/16 inches diameter. Then shaped to get an easy fit of my two inch rubber hose. I was OK with this method since the connecting hose allowed the two inlets on the bing carb inlet sufficient clean air for normal operation. On a later aircraft I used 2 inch tube. The hose clamp clearly compressed the hose more on the carb side than on the inlet box with the two inch tube.
Epoxy sticks to just about anything but oil and grease so it will make a good repair bond to the clean and roughed up polyester without a problem of bonding. Remember to rough up the aluminum as usual also.
So you have two methods, either an innie or outie method.
Note: The airbox does not have to be really smooth on the inside. It is a plenum not a tuned inlet. The bing carb sucks air rather than ram air entering the carb on the 912S. The transition humps and bumps should be minimized but just make both ends about the same and all will be fine. Remember, the bing has an inlet on the inside above and below the bore so make sure they can get reasonably clear air...
Of course Rotax wants you to buy their $1000 intake plenum. The only problem is it tends to lack support and since it hangs on the carb, it cracks those expensive 43mm rubber carb manifold to carb flange. Support the inlet plenum, that supports the carb and those rubber carb flange adapters last almost forever.
Just my opinion,
Best Regards to Mary also,
Bud Yerly
Best Regards,
Bud Yerly
| - The Matronics Europa-List Email Forum - | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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SwiftTG
Joined: 01 Oct 2018 Posts: 3
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Posted: Mon Sep 07, 2020 3:26 am Post subject: Re: Airbox for 912S |
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I just wanted to comment on a note in Buds reply regarding the "really cheap polyester chop and glass bit from Europa". I do not know what part is being referred to but nothing is now supplied from Europa in chop strand. As a relevant example the Mod 42 airbox is manufactured from 92125 cloth.
| - The Matronics Europa-List Email Forum - | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Europa-List |
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_________________ David Stanbridge
Europa Aircraft (2004) Limited
www.europa-aircraft.com
technical@europa-aircraft.com |
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budyerly@msn.com
Joined: 05 Oct 2019 Posts: 288 Location: Florida USA
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Posted: Mon Sep 07, 2020 4:25 am Post subject: Airbox for 912S |
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David,
And we thank you for the quality parts now manufactured.
There was a time in the early 2000s that even the gelcoat was flaking and cracking terribly on all the accessory parts like speed kits and cowls.
Thanks again,
Bud Yerly
Sent from Mail for Windows 10
From: SwiftTG (david.stanbridge(at)swifttg.com)
Sent: Monday, September 7, 2020 7:32 AM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Airbox for 912S
--> Europa-List message posted by: "SwiftTG" <david.stanbridge(at)swifttg.com>
I just wanted to comment on a note in Buds reply regarding the "really cheap polyester chop and glass bit from Europa". I do not know what part is being referred to but nothing is now supplied from Europa in chop strand. As a relevant example the Mod 42 airbox is manufactured from 92125 cloth.
--------
David Stanbridge
Europa Aircraft (2004) Limited
www.europa-aircraft.com
technical(at)europa-aircraft.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498165#498165
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matronics.com
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p; -Matt Dralle, List Admin.
http://www.matronics.com/contribution
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| - The Matronics Europa-List Email Forum - | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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churchy
Joined: 04 Nov 2011 Posts: 48
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Posted: Mon Sep 07, 2020 6:35 am Post subject: Airbox for 912S |
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Bud
Not just the accessories - I have a fuselage top with flaking ‘gelcoat’ which I am still trying to resolve.
Richard C-C
Sent from my iPad
Quote: | On 7 Sep 2020, at 13:30, Bud Yerly <budyerly(at)msn.com> wrote:

David,
And we thank you for the quality parts now manufactured.
There was a time in the early 2000s that even the gelcoat was flaking and cracking terribly on all the accessory parts like speed kits and cowls.
Thanks again,
Bud Yerly
Sent from Mail for Windows 10
From: SwiftTG (david.stanbridge(at)swifttg.com)
Sent: Monday, September 7, 2020 7:32 AM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Airbox for 912S
--> Europa-List message posted by: "SwiftTG" <david.stanbridge(at)swifttg.com>
I just wanted to comment on a note in Buds reply regarding the "really cheap polyester chop and glass bit from Europa". I do not know what part is being referred to but nothing is now supplied from Europa in chop strand. As a relevant example the Mod 42 airbox is manufactured from 92125 cloth.
--------
David Stanbridge
Europa Aircraft (2004) Limited
www.europa-aircraft.com
technical(at)europa-aircraft.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498165#498165
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pa-List">http://www.matronics.com/Navigator?Europa-List
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ums.matronics.com
===========
p; - NEW MATRONICS LIST WIKI -
matronics.com
===========
p; - List Contribution Web Site -
p; -Matt Dralle, List Admin.
http://www.matronics.com/contribution
===========
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| - The Matronics Europa-List Email Forum - | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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iancook_1(at)hotmail.com Guest
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Posted: Mon Sep 07, 2020 7:12 am Post subject: Airbox for 912S |
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Richard how is the building going. With Bicester closing down I don’t Alan Twigg has still not flown his MG yet. I now have about 70Hrs on mine,
Sent from my iPhone
Quote: | On 7 Sep 2020, at 15:38, Richard Churchill-Coleman <richard.churchill-coleman(at)sky.com> wrote:
 Bud
Not just the accessories - I have a fuselage top with flaking ‘gelcoat’ which I am still trying to resolve.
Richard C-C
Sent from my iPad
Quote: | On 7 Sep 2020, at 13:30, Bud Yerly <budyerly(at)msn.com> wrote:

David,
And we thank you for the quality parts now manufactured.
There was a time in the early 2000s that even the gelcoat was flaking and cracking terribly on all the accessory parts like speed kits and cowls.
Thanks again,
Bud Yerly
Sent from Mail for Windows 10
From: SwiftTG (david.stanbridge(at)swifttg.com)
Sent: Monday, September 7, 2020 7:32 AM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Europa-List: Re: Airbox for 912S
--> Europa-List message posted by: "SwiftTG" <david.stanbridge(at)swifttg.com>
I just wanted to comment on a note in Buds reply regarding the "really cheap polyester chop and glass bit from Europa". I do not know what part is being referred to but nothing is now supplied from Europa in chop strand. As a relevant example the Mod 42 airbox is manufactured from 92125 cloth.
--------
David Stanbridge
Europa Aircraft (2004) Limited
www.europa-aircraft.com
technical(at)europa-aircraft.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498165#498165
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===========
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matronics.com
===========
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p; -Matt Dralle, List Admin.
http://www.matronics.com/contribution
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alan.twigg775(at)gmail.co Guest
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Posted: Mon Sep 07, 2020 8:02 am Post subject: Airbox for 912S |
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Not flown yet but complete and paperwork at the LAA actually being worked right now.Alan
Sent from my iPhone
Quote: | On 7 Sep 2020, at 16:14, Ian Cook <IanCook_1(at)hotmail.com> wrote:
 Richard how is the building going. With Bicester closing down I don’t Alan Twigg has still not flown his MG yet. I now have about 70Hrs on mine,
Sent from my iPhone
Quote: | On 7 Sep 2020, at 15:38, Richard Churchill-Coleman <richard.churchill-coleman(at)sky.com> wrote:
 Bud
Not just the accessories - I have a fuselage top with flaking ‘gelcoat’ which I am still trying to resolve.
Richard C-C
Sent from my iPad
Quote: | On 7 Sep 2020, at 13:30, Bud Yerly <budyerly(at)msn.com> wrote:

David,
And we thank you for the quality parts now manufactured.
There was a time in the early 2000s that even the gelcoat was flaking and cracking terribly on all the accessory parts like speed kits and cowls.
Thanks again,
Bud Yerly
Sent from Mail for Windows 10
From: SwiftTG (david.stanbridge(at)swifttg.com)
Sent: Monday, September 7, 2020 7:32 AM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Airbox for 912S
--> Europa-List message posted by: "SwiftTG" <david.stanbridge(at)swifttg.com>
I just wanted to comment on a note in Buds reply regarding the "really cheap polyester chop and glass bit from Europa". I do not know what part is being referred to but nothing is now supplied from Europa in chop strand. As a relevant example the Mod 42 airbox is manufactured from 92125 cloth.
--------
David Stanbridge
Europa Aircraft (2004) Limited
www.europa-aircraft.com
technical(at)europa-aircraft.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=498165#498165
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ums.matronics.com
===========
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matronics.com
===========
p; - List Contribution Web Site -
p; -Matt Dralle, List Admin.
http://www.matronics.com/contribution
===========
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richard.holder(at)outlook Guest
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Posted: Wed Sep 09, 2020 1:34 am Post subject: Airbox for 912S |
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On 05/09/2020 16:01, Steven Pitt wrote
Quote: |
<stevenwpitt(at)me.com>
Now I have a dilemma. I have measured the diameter of
the inner carburettor at 45mm. The airbox outer tube is
48/49mm - the inner diameter 39 and 42mm (these
measurements after my fix - several layers of bid to
strengthen the orifices after they collapsed under the
tightness of the worm driven band).
I have never had a problem with the carburettors and
never given any thought to a mismatch between the two
diameters. I was always aware the the box was poorly
finished and the air intakes were easy to crush, but
with the bolt holding the box to the engine frame it
had never departed giving me an inflight issue.
It is also notable that the two orifices were not the
same size even before the collapse.
The only way I can see to equalise the two is to
rebuild the airbox as per Dave Ps suggestion - cut the
ends off - find an aluminium tube with inside diameter
of 45mm and bond that in with bid. Anyone got any tube
to that size?
Anyone else wishing to add any advice before I carve
the boxes up. Also what is the airbox made from? It
looks like chopped strand mat fibreglass.
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Steven, just seen this.
When my airbox tubes compressed I used short lengths of
steel exhaust pipe with the correct OD (to match the carb
inlet OD).
I dremelled away enough of the original fibreglass to get
the exhaust tube (ET) to fit nicely using the carbs as the
locational template. I drilled a few holes in the ET to
allow keying. I then resined (with a filler) in the ETs
without worrying about the actual orifice size.
When the resin had gone off I dremelled out all the
surplus resin on the inside leaving it reasonably smooth.
Much stronger than the original, and as the air passage is
now much larger than it was the engine runs less rich !
And I can do the Jubillee clips up tight. I bought short
lengths of silicone hose with ID to match the carb inlet.
Not patented !
Richard
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