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  #21  
Old 06-22-2015, 01:21 PM
xblueh2o xblueh2o is offline
 
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Quote:
Originally Posted by sailvi767 View Post
[ Here is what we have. It's clean and simple. I don't see how any failures could introduce FOD. The barrel rotates and opens the slots as a alternate source of air. I believe it is a ECI system.
George
Ok, what is this piece, how does it work, who makes it etc etc etc.
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  #22  
Old 06-22-2015, 01:37 PM
BillL BillL is offline
 
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Quote:
Originally Posted by sailvi767 View Post
[ Here is what we have. It's clean and simple. I don't see how any failures could introduce FOD. The barrel rotates and opens the slots as a alternate source of air. I believe it is a ECI system.
George
Quote:
Originally Posted by xblueh2o View Post
Ok, what is this piece, how does it work, who makes it etc etc etc.
What is this piece - from above ="alternate source of air"
how does it work, from above ="The barrel rotates and opens the slots"
who makes it - from above = "I believe it is a ECI system"

etc: who is buried in Grant's tomb? - = Grant, it is answered within the question

Bad day?
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  #23  
Old 06-22-2015, 02:14 PM
sailvi767 sailvi767 is offline
 
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I contacted Robbie Attaway about the alternate air system. It is not a ECI system. He designed the system and holds the copyright. Robbie believes it is the best system out there and I have to agree. It's very elegant and well made. He made several others but left the RV world to work overseas. He is back now and would make more or consider selling the patent but they are expensive. They only work with forward facing injected systems.
George
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  #24  
Old 06-22-2015, 02:14 PM
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airguy airguy is offline
 
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Easy there Bill...

I made a pretty good search of the ECI site looking for this, and it's not to be found - so I'm asking the same questions....

EDIT - George beat me to it. Bill can take the day off.
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Last edited by airguy : 06-22-2015 at 02:17 PM.
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  #25  
Old 06-22-2015, 03:29 PM
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wirejock wirejock is offline
 
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Default Alternate air

That's pretty slick. Works like the air control on a BBQ pit.
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  #26  
Old 06-22-2015, 03:44 PM
BillL BillL is offline
 
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Quote:
Originally Posted by airguy View Post
Easy there Bill...

I made a pretty good search of the ECI site looking for this, and it's not to be found - so I'm asking the same questions....

EDIT - George beat me to it. Bill can take the day off.
Sorry, I could not help my self. Guess I'm not as funny as I think.

Seriously, it is a slick looking design, very clever. It would appear to provide a non biased flow when in use. But - it does take some valuable space in the flow direction. DanH's unit is packaged in a very short length, and with a healthy flow area for the air filter. My installation will be challenged with a set back cowl. The Will James FAB appears that it will fit in that length and includes a spring operated alternate air door. Not as well documented as Dan's, but saves some development time.

I was thinking that maybe the alt air (filter bypass) was not really needed except in winter, but g-zero just caught a plastic bag reported here less than a month ago. His takeoff was executed on alt air and he returned to find the debris.
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  #27  
Old 06-22-2015, 04:02 PM
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DanH DanH is offline
 
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Durability aside, the question is pressure drop, both for the chosen filter, and when running on alternate or bypass air. The rotating sleeve approach is pretty cool, but should be checked for restriction.

Being located right at the throttle body inlet, it should also be checked to make sure it doesn't upset metering when used with a conventional Bendix-style fuel control (Bendix RSA, AFP FM150 or FM200, Precision Silver Hawk EX5, etc). They all rely on ram and venturi pressure to meter. The unit in the photo is an ECI, which is more like a Continental constant flow system. It delivers fuel based on RPM and throttle opening, not airflow measurement.
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  #28  
Old 06-29-2015, 08:44 AM
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rswalden rswalden is offline
 
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I had an oil line come apart on a rented Piper Arrow while crossing the Rockies at 12,000 feet. The oil quickly saturated the air filter, resulting in a loss of power. The Alternate Air lever (filter bypass) helped restore power long enough to find a place to put the airplane down safely.

During my RV-7A build, I made sure a filter bypass/alternate air system was installed.
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  #29  
Old 06-29-2015, 01:38 PM
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az_gila az_gila is offline
 
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Location: 57AZ - NW Tucson area
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Question

Quote:
Originally Posted by BobTurner View Post
While your definitions are perhaps 'cleaner' or clearer, they re not the customary ones. Virtually every normally certificated aircraft that I've seen labels the knob 'alternate air' when in fact it is a filter bypass.
Not always the case on certified planes - sometimes the "Carb Heat" function is also a filter bypass, like on the Grumman Cheetah, and it's labeled as "Carb Heat".

However, the Carb Heat air goes through the air filter on my Grumman Tiger and there is no filter bypass available. This might be allowed by the use of a coarse screen on the start of the Air Intake to Filter Box hose above #3 cylinder...


If this is the case, perhaps the RV risk could be reduced by adding a coarse screen in the cowling intake and letting the carb heat function everyone has act as the safety measure for the dead bird/paper bag ingestion problem?


The Grumman knob for "Alternate Air" is for the static ports bypass only...
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  #30  
Old 12-30-2015, 06:04 AM
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dbuds2 dbuds2 is offline
 
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Location: Palm Beach Gardens, Fl
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Default Mine is MIA

Pulled cowls yesterday for oil change, door and all mounting hardware has left the mother ship. About to rebuild without alt air. New parts on the way from Van's already, but, seriously wondering how to have the function without risk of more fastener failures. The fiberglass filter holder is just too flimsy to support pop rivets (at least when they fail they should go down and out the cowl instead of up and in the throttle body, thats what i'm telling myself).

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Last edited by dbuds2 : 12-30-2015 at 08:39 AM.
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