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flying-nut(at)cfl.rr.com
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 Posted: Fri May 23, 2014 1:57 pm Post subject: alt air |
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What timing! Friday mornings the airport hangar rats gather to discuss aviation. There's a -7 and two -10 builders. Both the -7 builder and I (-10 if you don't do math well) were discussing the FAB and the connection to the lower cowl. The subject turned to carb heat and alt. air. I dislike the Van's approach to alt. air and we brainstormed .... how about a butterfly? Hmmm. I came home and this is what I came up with ....
if the picture comes through.
The Van's alt air fitting opening is 2.5" which has a 4.9" square area.
The 'plank' is 1" X 5" and the 'tube' is 2.5" dia.
I'll probably use aluminum for the tube. ACS 6061 T6 03-38320 is only 4.35/ft. We talked about the butterfly being an ellipse rather than a disk so it seals better.
There's plenty of room between the FAB and the lower cowl on the RV-10. The 'dot' is centered on the hole in the FAB. Some fillet work and I'll glass it right on the FAB.
Not an automatic alt air .... but better than Van's .... IMHO
Linn
[img]cid:part1.02050507.05080707(at)cfl.rr.com[/img]
On 5/23/2014 4:49 PM, Kelly McMullen wrote:
| Quote: | --> RV10-List message posted by: Kelly McMullen <kellym(at)aviating.com> (kellym(at)aviating.com)
Has anyone attempted to engineer an automatic alternate air?? My fuel injected Mooney has such, with a round disk attached to a hole cut so that there is a metal cross with 4 openings rather than open hole. The disk covers that, is held in place with a single bolt with a spring on it pressing the disk in closed position. 3-4 lb force lifts the disk enough for air to bypass the filter from inside cowling. Only downside is you don't really know whether it has opened or not. I've seen 2 place RVs that had similar arrangement with hinged rectangular door that was spring loaded.
On 5/23/2014 9:20 AM, Jeff Carpenter wrote:
| Quote: | If you change the hole locations you will likely change your cable lengths and it is no easy trick to figure what those lengths need to be (ask me how I know).
Jeff Carpenter
40304
just about ready for paint.
On May 23, 2014, at 8:22 AM, Sandra & Rick Lark wrote:
| Quote: | Hi all, wondering if anyone has recommendations on any better locations for the throttle, prop, mixture and alternate air penetrations?
I’m just about to bolt my engine mount on for the last time and I haven’t drilled any holes for those 4 items yet. I`m wondering if the throttle and alternate air holes could be below the other 2, or if it makes any difference at all?
Thx, Rick
#40956
Southampton. Ont
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05/23/14
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Fri May 23, 2014 3:48 pm Post subject: Re: alt air |
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Will it clear the nose gear strut?
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Bob Turner
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flying-nut(at)cfl.rr.com
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| Posted: Fri May 23, 2014 3:58 pm Post subject: alt air |
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On 5/23/2014 7:48 PM, Bob Turner wrote:
| Quote: |
Will it clear the nose gear strut? Even when you remove the lower cowl by dropping it down?
It's a long way to the nose strut ..... the end of the 'tube' in the pic
|
is only 5" aft of the FAB.
I could be flying if I didn't waste time on the 'simple' mods!!!
Linn
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Kelly McMullen
Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ
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| Posted: Fri May 23, 2014 6:56 pm Post subject: alt air |
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This is what I was trying to describe. If the attachment makes it through.
On Fri, May 23, 2014 at 2:56 PM, Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)> wrote:
| Quote: | What timing! Friday mornings the airport hangar rats gather to discuss aviation. There's a -7 and two -10 builders. Both the -7 builder and I (-10 if you don't do math well) were discussing the FAB and the connection to the lower cowl. The subject turned to carb heat and alt. air. I dislike the Van's approach to alt. air and we brainstormed .... how about a butterfly? Hmmm. I came home and this is what I came up with ....
if the picture comes through.
|
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
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flying-nut(at)cfl.rr.com
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| Posted: Sat May 24, 2014 4:07 am Post subject: alt air |
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On 5/23/2014 10:55 PM, Kelly McMullen wrote:
| Quote: | This is what I was trying to describe. If the attachment makes it through.
|
It did. Like you said, you don't know if it's going to work when you need it. Things get stuck with age. A round piece of rubber held in the middle would work similarly, but how thick/stiff does the rubber need to be ...... too much engineering for a simple guy like me. I like positive open/close.
Linn
[quote]
On Fri, May 23, 2014 at 2:56 PM, Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)> wrote:
| Quote: | What timing! Friday mornings the airport hangar rats gather to discuss aviation. There's a -7 and two -10 builders. Both the -7 builder and I (-10 if you don't do math well) were discussing the FAB and the connection to the lower cowl. The subject turned to carb heat and alt. air. I dislike the Van's approach to alt. air and we brainstormed .... how about a butterfly? Hmmm. I came home and this is what I came up with ....
if the picture comes through.
|
No virus found in this message.
Checked by AVG - www.avg.com
05/23/14 [b]
| | - The Matronics RV10-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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carl.froehlich(at)verizon
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| Posted: Sat May 24, 2014 5:18 am Post subject: alt air |
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One thought – in all probability few of us will ever have a need to use alternate engine air. As such the design needs to be for something that opens, but closing can wait for landing if need be.
I posted a note a while back on modifying the FAB to prevent a recurring problem I had on the 8A, the filter ablating the bottom of the fiberglass air box and the filter deforming from a cylinder to a cone. Both issues lead to the filter loosing contact with the top plate. Here is the original post:
This is a mod to the air box I did on the RV-10, and just now back fitted onto the RV-8A.
Over the years with the RV-8A I’ve had to repair the air box and replace the filter. As you can see from the first photo, the bottom of the filter deforms (curves in). This tends to shorten the filter such that it drops out of the top and impairs the seal with the top plate. I also had to add fiberglass to the bottom of the air box as the relative motion between the bottom of the air filter the air box eroded away the fiberglass bottom.
The fix was to add a .032” aluminum plate to the bottom of the air box. The plate eliminates the bottom erosion and the added brackets hold the filter shape. A side benefit is that alternate air door now sandwiches the bottom fiberglass between two piece of metal making a sturdier install. I also took the step to add proseal between the aluminum plate and the air box bottom.
One other mod done for the RV-10 was to flip FAB top plate over so it goes over the fiberglass bottom portion. This allowed me to use the larger K&N E-1000 filter (last photo). I just finished the second annual on the RV10 and can report the filter has retained it shape.
Carl
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Linn Walters
Sent: Saturday, May 24, 2014 8:06 AM
To: rv10-list(at)matronics.com
Subject: Re: alt air
On 5/23/2014 10:55 PM, Kelly McMullen wrote:
| Quote: |
This is what I was trying to describe. If the attachment makes it through.
|
It did. Like you said, you don't know if it's going to work when you need it. Things get stuck with age. A round piece of rubber held in the middle would work similarly, but how thick/stiff does the rubber need to be ...... too much engineering for a simple guy like me. I like positive open/close.
Linn
On Fri, May 23, 2014 at 2:56 PM, Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)> wrote:
What timing! Friday mornings the airport hangar rats gather to discuss aviation. There's a -7 and two -10 builders. Both the -7 builder and I (-10 if you don't do math well) were discussing the FAB and the connection to the lower cowl. The subject turned to carb heat and alt. air. I dislike the Van's approach to alt. air and we brainstormed .... how about a butterfly? Hmmm. I came home and this is what I came up with ....
if the picture comes through.
No virus found in this message.
Checked by AVG - www.avg.com
05/23/14
http://forums.matronics.com[/url] - List Contribution Web generous nbsp; --> http://www.matronics.com/c=[/b] [/quote]
| | - The Matronics RV10-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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n223rv(at)wolflakeairport
Guest
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| Posted: Sat May 24, 2014 5:31 am Post subject: alt air |
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In 16 years of flying, I've never needed to use alternate air. I'm happy with Vans simple solution. I don't intend to ever need it and if I do, I know it'll work.
For me, it's just not something that needs re-engineered....
Sent from my iPhone
On May 23, 2014, at 5:56 PM, Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)> wrote:
[quote] What timing! Friday mornings the airport hangar rats gather to discuss aviation. There's a -7 and two -10 builders. Both the -7 builder and I (-10 if you don't do math well) were discussing the FAB and the connection to the lower cowl. The subject turned to carb heat and alt. air. I dislike the Van's approach to alt. air and we brainstormed .... how about a butterfly? Hmmm. I came home and this is what I came up with ....
if the picture comes through.
The Van's alt air fitting opening is 2.5" which has a 4.9" square area.
The 'plank' is 1" X 5" and the 'tube' is 2.5" dia.
I'll probably use aluminum for the tube. ACS 6061 T6 03-38320 is only 4.35/ft. We talked about the butterfly being an ellipse rather than a disk so it seals better.
There's plenty of room between the FAB and the lower cowl on the RV-10. The 'dot' is centered on the hole in the FAB. Some fillet work and I'll glass it right on the FAB.
Not an automatic alt air .... but better than Van's .... IMHO
Linn
<ALTERNATE AIR MOD 03.JPG>
On 5/23/2014 4:49 PM, Kelly McMullen wrote:
| Quote: | --> RV10-List message posted by: Kelly McMullen <kellym(at)aviating.com> (kellym(at)aviating.com)
Has anyone attempted to engineer an automatic alternate air?? My fuel injected Mooney has such, with a round disk attached to a hole cut so that there is a metal cross with 4 openings rather than open hole. The disk covers that, is held in place with a single bolt with a spring on it pressing the disk in closed position. 3-4 lb force lifts the disk enough for air to bypass the filter from inside cowling. Only downside is you don't really know whether it has opened or not. I've seen 2 place RVs that had similar arrangement with hinged rectangular door that was spring loaded.
On 5/23/2014 9:20 AM, Jeff Carpenter wrote:
| Quote: | If you change the hole locations you will likely change your cable lengths and it is no easy trick to figure what those lengths need to be (ask me how I know).
Jeff Carpenter
40304
just about ready for paint.
On May 23, 2014, at 8:22 AM, Sandra & Rick Lark wrote:
| Quote: | Hi all, wondering if anyone has recommendations on any better locations for the throttle, prop, mixture and alternate air penetrations?
I’m just about to bolt my engine mount on for the last time and I haven’t drilled any holes for those 4 items yet. I`m wondering if the throttle and alternate air holes could be below the other 2, or if it makes any difference at all?
Thx, Rick
#40956
Southampton. Ont
*
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blue; text-decoration: underline; ">http://forums.matronics.com
style="color: blue; text-decoration: underline; ">http://www.matronics.com/contribution
*
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-----
No virus found in this message.
Checked by AVG - www.avg.com
05/23/14
|
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flying-nut(at)cfl.rr.com
Guest
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| Posted: Sat May 24, 2014 5:44 am Post subject: alt air |
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That filter is ugly! I saw pics from other builders that were just as bad.
IMHO I think the 'deforming' of the filter may be due to the rubber on the filter having a problem with 100LL ..... or ethanol mogas .....
The filter just wasn't made for that environment.
I'm also adding a aluminum plate to the bottom of the FAB to counter the FG wearing by the filter .... saw some more ugly pics on this list. I'll add a drain hole next to the filter so it drips down into my 'new' alt air box.
We install a lot of things that we may never need .... heated pitot, ELT, windshield defrosters, fire extinguishers .... to name a few. However, when we do need them they're invaluable ......
Linn
On 5/24/2014 9:17 AM, Carl Froehlich wrote:
[quote] <![endif]--> <![endif]-->
One thought – in all probability few of us will ever have a need to use alternate engine air. As such the design needs to be for something that opens, but closing can wait for landing if need be.
I posted a note a while back on modifying the FAB to prevent a recurring problem I had on the 8A, the filter ablating the bottom of the fiberglass air box and the filter deforming from a cylinder to a cone. Both issues lead to the filter loosing contact with the top plate. Here is the original post:
This is a mod to the air box I did on the RV-10, and just now back fitted onto the RV-8A.
Over the years with the RV-8A I’ve had to repair the air box and replace the filter. As you can see from the first photo, the bottom of the filter deforms (curves in). This tends to shorten the filter such that it drops out of the top and impairs the seal with the top plate. I also had to add fiberglass to the bottom of the air box as the relative motion between the bottom of the air filter the air box eroded away the fiberglass bottom.
The fix was to add a .032” aluminum plate to the bottom of the air box. The plate eliminates the bottom erosion and the added brackets hold the filter shape. A side benefit is that alternate air door now sandwiches the bottom fiberglass between two piece of metal making a sturdier install. I also took the step to add proseal between the aluminum plate and the air box bottom.
One other mod done for the RV-10 was to flip FAB top plate over so it goes over the fiberglass bottom portion. This allowed me to use the larger K&N E-1000 filter (last photo). I just finished the second annual on the RV10 and can report the filter has retained it shape.
Carl
From: owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com) [mailto:owner-rv10-list-server(at)matronics.com (owner-rv10-list-server(at)matronics.com)] On Behalf Of Linn Walters
Sent: Saturday, May 24, 2014 8:06 AM
To: rv10-list(at)matronics.com (rv10-list(at)matronics.com)
Subject: Re: alt air
On 5/23/2014 10:55 PM, Kelly McMullen wrote:
| Quote: |
This is what I was trying to describe. If the attachment makes it through.
|
It did. Like you said, you don't know if it's going to work when you need it. Things get stuck with age. A round piece of rubber held in the middle would work similarly, but how thick/stiff does the rubber need to be ...... too much engineering for a simple guy like me. I like positive open/close.
Linn
On Fri, May 23, 2014 at 2:56 PM, Linn Walters <flying-nut(at)cfl.rr.com (flying-nut(at)cfl.rr.com)> wrote:
What timing! Friday mornings the airport hangar rats gather to discuss aviation. There's a -7 and two -10 builders. Both the -7 builder and I (-10 if you don't do math well) were discussing the FAB and the connection to the lower cowl. The subject turned to carb heat and alt. air. I dislike the Van's approach to alt. air and we brainstormed .... how about a butterfly? Hmmm. I came home and this is what I came up with ....
if the picture comes through.
No virus found in this message.
Checked by AVG - www.avg.com
05/23/14
http://forums.matronics.com - List Contribution Web generous nbsp; --> http://www.matronics.com/c=
No virus found in this message.
Checked by AVG - www.avg.com
05/24/14 [b]
| | - The Matronics RV10-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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Kellym
Joined: 10 Jan 2006
Posts: 1706
Location: Sun Lakes AZ
|
| Posted: Sat May 24, 2014 7:06 am Post subject: alt air |
|
|
The Mooney alt air is very easy to check for freedom to operate, just
push on the plate anytime lower cowling is open, or hook up a fish scale
to it when air filter is off to verify the tension is within specs. The
air pressure needed to open a given area of flat plate is pretty easy to
calculate. I've never found any problem with it sticking when checking
it. I like not needing to run an extra cable through the firewall and
not needing an extra knob some where on the panel.
On 5/24/2014 5:05 AM, Linn Walters wrote:
| Quote: | On 5/23/2014 10:55 PM, Kelly McMullen wrote:
> This is what I was trying to describe. If the attachment makes it
> through.
It did. Like you said, you don't know if it's going to work when you
need it. Things get stuck with age. A round piece of rubber held in
the middle would work similarly, but how thick/stiff does the rubber
need to be ...... too much engineering for a simple guy like me. I
like positive open/close.
Linn
> On Fri, May 23, 2014 at 2:56 PM, Linn Walters <flying-nut(at)cfl.rr.com
> <mailto:flying-nut(at)cfl.rr.com>> wrote:
>
> What timing! Friday mornings the airport hangar rats gather to
> discuss aviation. There's a -7 and two -10 builders. Both the
> -7 builder and I (-10 if you don't do math well) were discussing
> the FAB and the connection to the lower cowl. The subject turned
> to carb heat and alt. air. I dislike the Van's approach to alt.
> air and we brainstormed .... how about a butterfly? Hmmm. I
> came home and this is what I came up with ....
> if the picture comes through.
> No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com>
> 05/23/14
>
*
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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
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flying-nut(at)cfl.rr.com
Guest
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| Posted: Sat May 24, 2014 12:49 pm Post subject: alt air |
|
|
On 5/24/2014 11:05 AM, Kelly McMullen wrote:
| Quote: |
The Mooney alt air is very easy to check for freedom to operate, just
push on the plate anytime lower cowling is open, or hook up a fish
scale to it when air filter is off to verify the tension is within
specs. The air pressure needed to open a given area of flat plate is
pretty easy to calculate. I've never found any problem with it
sticking when checking it. I like not needing to run an extra cable
through the firewall and not needing an extra knob some where on the
panel.
I understand and agree on both counts. I didn't know anything about the
|
Van's alt air setup when I ran the control ......
Linn
| Quote: |
On 5/24/2014 5:05 AM, Linn Walters wrote:
> On 5/23/2014 10:55 PM, Kelly McMullen wrote:
>> This is what I was trying to describe. If the attachment makes it
>> through.
> It did. Like you said, you don't know if it's going to work when you
> need it. Things get stuck with age. A round piece of rubber held in
> the middle would work similarly, but how thick/stiff does the rubber
> need to be ...... too much engineering for a simple guy like me. I
> like positive open/close.
> Linn
>>
>>
>> On Fri, May 23, 2014 at 2:56 PM, Linn Walters <flying-nut(at)cfl.rr.com
>> <mailto:flying-nut(at)cfl.rr.com>> wrote:
>>
>> What timing! Friday mornings the airport hangar rats gather to
>> discuss aviation. There's a -7 and two -10 builders. Both the
>> -7 builder and I (-10 if you don't do math well) were discussing
>> the FAB and the connection to the lower cowl. The subject turned
>> to carb heat and alt. air. I dislike the Van's approach to alt.
>> air and we brainstormed .... how about a butterfly? Hmmm. I
>> came home and this is what I came up with ....
>> if the picture comes through.
>>
>>
>>
>>
>>
>>
>> No virus found in this message.
>> Checked by AVG - www.avg.com <http://www.avg.com>
>> 05/23/14
>>
>
> *
> *
-----
No virus found in this message.
Checked by AVG - www.avg.com
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