REFLECTOR: Alternate Air

Andy Millin amillin at sbcglobal.net
Sat Jul 19 10:27:06 CDT 2008


I have been looking on the net for possible solutions.

I have seen the pictures of the alternate air on Rich Guerra's plane.  It
too has a hinge and spring.

Vans had designed a hinged door as well.  It was held closed by a magnet
instead of a spring.

A year or so ago they had to issue a KPC calling for a cable to be attached.
The door was opening under high power settings during normal operation.

The big question is:  How do you know the door stays closed during normal
operations and will open when it is really needed?

Has anyone tested their solution.  Taken the cowl off and verified the door
is closed at full throttle.  Obstructed the filter and verified the door
opens.

Andy


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brian Michalk
Sent: Friday, July 18, 2008 11:47 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Alternate Air


Renee Dugas did something similar.

doug.holub at tx.rr.com wrote:
> I'm doing my alternate air this week, too. I've got a fiberglass elbow 
> that connects to the air intake. I'm cutting a square flap out of the 
> bottom of that, and then putting it back in with a springy hinge on 
> one edge. (That springy hinge will be one or two plies of bid.) When 
> there is normal air pressure at the intake, the flap will remain 
> closed. If something clogs the air filter, the resulting vaccuum will 
> open the flap.
> 
> After I thought of doing it this way, I checked online to see if 
> anyone else had done it that way. I found a couple of production 
> airplanes that had "automatic alternate air" which were springy hinged 
> flaps. One was the SR22, I think. It also has a microswitch on the 
> flap so that the pilot will know when alternate air is being used.
> 
> Doug Holub
> Waiting on the propeller. 68/78 two blade Prince P-tip. I ordered it 
> in January.
> 
> ---- Andy Millin <amillin at sbcglobal.net> wrote:
>> For those running an intake filter.  I am looking for ideas on 
>> implementing an alternate air source.  I would love to hear and see 
>> (if you have the picture).
>>
>>  
>>
>> Thanks,
>>
>>  
>>
>> Andy
>>
>>  
>>
>> =====================================
>>
>>  
>>
>> Andy Millin
>>
>> amillin at sbcglobal.net
>>
>>  
>>
> 
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