Today's Message Index:
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1. 01:54 PM - Re: How to eliminate noise on COMM 1 (GNS430W) (Mike Whisky)
2. 03:39 PM - Airbox mod (Chris Hukill)
3. 05:55 PM - Re: Airbox mod (Bob Turner)
4. 06:08 PM - Re: Re: Airbox mod (Kelly McMullen)
5. 06:37 PM - Re: Airbox mod (David Saylor)
6. 06:59 PM - Re: Airbox mod (Linn Walters)
7. 07:21 PM - Re: Airbox mod (Tim Olson)
Message 1
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| Subject: | Re: How to eliminate noise on COMM 1 (GNS430W) |
I just wanted to give you an update on my noise issue. Following the advice on
de-activating one system after the other I was able to narrow it down to the nav
lights. Long story short Aeroleds did sent me new ones and the noise is gone.
Great customer service!
Regards
Michael
--------
RV-10 builder (flying)
#511
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=429307#429307
Message 2
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I have yet another mod that I did, this time to the fab airbox. With all the
feedback of the problems that some have had with the various Vans versions
of alternate air devises, I wasn't thrilled with any of them. My design
criteria is that there should be zero chance of ingesting anything into the
motor. That includes hardware that came loose from the fab, or anything else
the engine could suck in while in "alternate air" mode. That would even
include dirty, dusty or sandy air. The second feature would be that the
bypass must occur automatically. If I suck in a bird at 200 feet agl, right
after takeoff, I don't want to have to remember that bypass knob in the few
seconds before crashing. The solution was to use reed valves, as others have
done, but locate them not below the fab, but behind it. The aft section of
the filter is isolated with small dams, and when the reed valves suck in,
the air goes thru that section of the filter that isn't contaminated. In
that mode you still are breathing clean air, although at a slight decrease
in power due to loss of ram air. How much power? Tests on my flying RV8
showed about a 10% reduction during full power static runs. I will run a
similar test when I get the 10 flying. I have attached pictures, but they
may not come thru. If interested email me off-forum and I'll send them.
Chris Hukill
still being baffled by baffles
Message 3
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I'm all in favor of a better mousetrap, but a few things would bother me here.
1. I'd worry about the 'good' part of the filter getting water soaked from the
inside, then later freezing.
2. At WOT you'll need something like a 200 ft/sec airflow thru those three holes,
not sure if that is possible.
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=429320#429320
Message 4
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It did occur to me that one could mount a plate in front of the air filter
to fore the air to make a turn, so that any snow, sleet, ice, hail etc
would impact on the plate rather than the filter. Some cars used to have an
arrangement like that.
I think if you are getting enough water to wet the back side of the filter
you are in weather a light single has no business being there. Any time air
has to change direction any liquid or solids will not make the turn. If the
air is cold enough to refreeze water it means it is cold enough for ice on
the airframe as well. I don't know what prompted Vans to even offer an
alternate air, since they obviously believe in Day VFR as the conditions to
fly an RV.
So far I have not been convinced of the need for alternate air in the FAB
as the plans show it. Maybe if you fly through a volcanic ash cloud you
might severely plug the whole filter. And then you are faced with either
loss of power or ruining the engine by opening the alt air.
On Mon, Aug 25, 2014 at 5:54 PM, Bob Turner <bobturner@alum.rpi.edu> wrote:
>
> I'm all in favor of a better mousetrap, but a few things would bother me
> here.
> 1. I'd worry about the 'good' part of the filter getting water soaked from
> the inside, then later freezing.
> 2. At WOT you'll need something like a 200 ft/sec airflow thru those three
> holes, not sure if that is possible.
>
> --------
> Bob Turner
> RV-10 QB
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=429320#429320
>
>
Message 5
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Chris,
That's some beautiful work. Got a couple comments:
I don't have any numbers for how much filter area you need, but knowing
Vans, I kind of doubt they provided any extra. What I'm saying is, how do
you know you have adequate filter area remaining after you dam off the
alternate part?
Personally, I kind of think of the air filter as doing it's job over the
life of the engine. The odds of inhaling an adequately foreign object --
while running alternate air -- seem small enough to me to tolerate the risk.
How do you know it's working? Indicator system? Some other parameter that
changes when the alternate is open?
While you're at it, look in the archives about mounting an aluminum plate
under the filter. It tends to wear through the bottom of the FAB.
Blue Skies,
--Dave
On Mon, Aug 25, 2014 at 3:38 PM, Chris Hukill <cjhukill@cox.net> wrote:
> I have yet another mod that I did, this time to the fab airbox. With all
> the feedback of the problems that some have had with the various Vans
> versions of alternate air devises, I wasn't thrilled with any of them. My
> design criteria is that there should be zero chance of ingesting anything
> into the motor. That includes hardware that came loose from the fab, or
> anything else the engine could suck in while in "alternate air" mode. That
> would even include dirty, dusty or sandy air. The second feature would be
> that the bypass must occur automatically. If I suck in a bird at 200 feet
> agl, right after takeoff, I don't want to have to remember that bypass knob
> in the few seconds before crashing. The solution was to use reed valves, as
> others have done, but locate them not below the fab, but behind it. The aft
> section of the filter is isolated with small dams, and when the reed valves
> suck in, the air goes thru that section of the filter that isn't
> contaminated. In that mode you still are breathing clean air, although at a
> slight decrease in power due to loss of ram air. How much power? Tests on
> my flying RV8 showed about a 10% reduction during full power static runs. I
> will run a similar test when I get the 10 flying. I have attached pictures,
> but they may not come thru. If interested email me off-forum and I'll send
> them.
> Chris Hukill
> still being baffled by baffles
Message 6
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At least the alternate air wars have pushed all the other wars aside for
the time being. I don't like any control that I can't reverse. That's
what drove me to this:
The air hole in the bottom of the FAB is the same size as Van's sliding
one. There is a piece of screen over the hole to keep out any FOD.
We've seen what large birds can do .... coming through the windshield
...... and one that nails the inlet in the cowl could strangle your
engine if you don't have alt air. I have to agree with Kelly though
.... freezing rain or snow that will plug the filter will only occur if
you're flying where you shouldn't be.
Linn
Message 7
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You guys with the "bird through the cowl" into the intake are giving me a chuckle.
Talk about something with itty bitty small odds.... And if one DID go right
into the snorkel, it would probably explode the FAB anyway, giving you a *really*
large alternate air opening.
I don't know much, but other than the fact that the FAB definitely needs beefing
up with a metal plate for the filter to rub on, I just don't see that much that
needs more improving over a swing door in the bottom. I don't care if I can
re-set it in flight, because it'll fly fine for the remainder of that flight
anyway, and I can do it on the ground. Opening it means you had an emergency.
I'm happy to take 20 minutes or whatever out of my day after a true emergency.
And in 1000+ hours I haven't had the slightest interest in pulling the knob
in the first place. All of this should be a real rare occurrence....not something
like pulling carb heat on a carbureted engine...
Tim
> On Aug 25, 2014, at 8:58 PM, Linn Walters <flying-nut@cfl.rr.com> wrote:
>
> At least the alternate air wars have pushed all the other wars aside for the
time being. I don't like any control that I can't reverse. That's what drove
me to this:
> <alt air mod 01.JPG>
>
> The air hole in the bottom of the FAB is the same size as Van's sliding one.
There is a piece of screen over the hole to keep out any FOD. We've seen what
large birds can do .... coming through the windshield ...... and one that nails
the inlet in the cowl could strangle your engine if you don't have alt air.
I have to agree with Kelly though .... freezing rain or snow that will plug
the filter will only occur if you're flying where you shouldn't be.
> Linn
>
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