REFLECTOR: Alternate Air

Chuck Jensen cjensen at dts9000.com
Sat Jul 19 15:38:00 CDT 2008


My Alt Air was also by Prudhomme, but my door is on housing around the filter instead of at the end of the hallway leading to the filter housing, but the concept is the same.  Seems to have worked adequately, though a proximity sensor with indication on the panel to indicate open/closed would be very interesting.  I have that on my ToDo list for February 12, 2013.

Chuck Jensen


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of doug.holub at tx.rr.com
Sent: Saturday, July 19, 2008 2:16 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Alternate Air


I think this is what you're looking for: http://www.tvbf.org/gallery/?dir=engines%2Fplenum_jean_prudhomme
---- Andrew Ellzey <ajlz72756 at yahoo.com> wrote: 
> Someone on the reflector about a year or two ago showed pictures of an air filter assembly that was attached to their firewall and ran up to the left naca scoop. Their engine air intake was pointing straight at the firewall. This is the same configuration that I would like to copy. If this person is still on the reflector, could I get some pictures of this setup. This person also had an alternate air door.
> Andy Ellzey
> 
> 
> 
> ----- Original Message ----
> From: Andy Millin <amillin at sbcglobal.net>
> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> Sent: Saturday, July 19, 2008 10:27:06 AM
> Subject: Re: REFLECTOR: Alternate Air
> 
> 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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