Air filter for inverted engines, what do you use?

[John Lindberg]

I need to put a air filter on my inverted ST 51 and my PA 51 to keep dirt out, what do you suggest out there in C/L land? Cannot find Bru-Line filters, one I am familar with. Thanks for any input. 

[Balsa Butcher]

Piece of panty hose fabric held on by a rubber faucet washer. A single layer is all you need. Multiple layers can be used to tune the engine as they effectively decrease air flow. I would recommend that your wife remove the clothing item before you take a pair of scissors to it.

[Dave_Trible]

I too use the panty hose and O-ring.  I've had it happen twice that the engine sucked in the filter medium from the Bru-lines.  Have to say those were anything but new.  The word here I think is to change whatever you use pretty often.

Dave

I'm single these days so it's a strange thing to go to the checkout with panty hose-get strange looks.....

[Frank Imbriaco]

McMaster- Carr sells  a variety of super fine sceen discs; about 1" in diameter. Center on carb, form fit , one  small wire tie and you're done. Never lost one on my R/C pattern  or Ukie ships. And ,I can't detect any appreciable restriction.

The only down side is you have to buy a large quantity ( 50 or 100 per package), so share them with your flying buddies.
But, they're reasonably priced.

[Brett Buck]

McMaster- Carr sells  a variety of super fine sceen discs; about 1" in diameter. Center on carb, form fit , one  small wire tie and you're done. Never lost one on my R/C pattern  or Ukie ships. And ,I can't detect any appreciable restriction.

The only down side is you have to buy a large quantity ( 50 or 100 per package), so share them with your flying buddies.
But, they're reasonably priced.

  All of these have some restriction (and people have stacked panty hose layers to do fine adjustments). But the biggest benefit seems to be that it turbulates the air and makes the flow state and mixing inside the venturi more consistent.

   Brett

[Chris McMillin]

I agree with that, Brett. I could always tell when my Bru-Line jobs holed on the old ST 60 because it would start a little bit of a rattle and charge in certain places.
Chris...

[Trostle]

Deleted for poor attempt at humor.

KT

[John Lindberg]

I suppose it is because the intake is closer to the ground, put my last Bru-line on a profile, need a couple more. My case is I want to fly off a baseball diamond that has a rather sandy infield, grass is too thick to take off of. The paved surface we usually use gets hot this time of year. Should put a filter on all engines, I see your point. 

[john e. holliday]

Go to your local carpet retailer and see if they have a scrap peice.   I use mine  which is about two feet wide and about 15 feet long for flying out of grass that is not short enough.  I do use big spikes to hold it in place as it takes a set while rolled up and makes for a lumpy take off strip.   

[Joe Yau]

I too use the panty hose and O-ring.  I've had it happen twice that the engine sucked in the filter medium from the Bru-lines.  Have to say those were anything but new.  The word here I think is to change whatever you use pretty often.

Dave

I'm single these days so it's a strange thing to go to the checkout with panty hose-get strange looks.....

I used both also..    but I've had issue using the Bru-lines ones on a Saito .56. the problem is when it back fires or if it runs backwards.. it would melt the foam.  

[Randy Cuberly]

Deleted for poor attempt at humor.

KT

Keith,
I guess I'm always in "poor humor" because it made me laugh... .  Actually I wondered the same thing.  A filter is a filter is a filter...
I use panty hose mostly because the other types are usually too big to fit inside my cowlings.

Randy C.

[Bill Little]

I have used the panty hose/O ring with success so when my final stash of the Bru Line filters is gone, the pantyhose is what I will use.  I generally just use one layer, so far I have not played around with the "tuning effects" of multiple layers.

BIG Bear
RNMM/AMM

[Randy Cuberly]

I have used the panty hose/O ring with success so when my final stash of the Bru Line filters is gone, the pantyhose is what I will use.  I generally just use one layer, so far I have not played around with the "tuning effects" of multiple layers.

BIG Bear
RNMM/AMM

Only reccommendation is to check the o-ring often (like before every flight).  If the o-ring loosens the elastic material in the panty hose relaxes and the mesh closes up and becomes more restrictive.  I had the engine suddenly start to richen one day and couldn't figure out why until I noticed the filter material was much darker and more closed than normal.

One more thing to check...  However, the tuning effect is very real and can be a real boon in some cases.

Randy C.

[louie klein]

John, Take a look at " i heard a rumor " post. There is a picture of the filter on an inverted engine!---LOUIE

[Bill Little]

Only reccommendation is to check the o-ring often (like before every flight).  If the o-ring loosens the elastic material in the panty hose relaxes and the mesh closes up and becomes more restrictive.  I had the engine suddenly start to richen one day and couldn't figure out why until I noticed the filter material was much darker and more closed than normal.

One more thing to check...  However, the tuning effect is very real and can be a real boon in some cases.

Randy C.

Thanks, Randy.  My wife has been a Nurse for over 40 years so there are a lot of white pantyhose left over.  This makes good material for filters!  You can tell pretty quick when it is getting dirty, etc..

When I get back to flying, I am going to play around with the layers so that I get a good feel for what does what.  I am familiar with going from a green to a black filter with the Bru Line.

Thanks, again!  I will check on the tightness fairly often.
Bill