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wild.blue(at)verizon.net
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 Posted: Sun Jun 11, 2006 10:02 am Post subject: carb heat, filtration |
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Hi Phil--
As others have said, the "funnels" are intended to provide heated air to the carburetor. Keep in mind that, like a -52, CJ's have a pressure carburetor, so "carb heat" isn't really a necessity, but alternate air is. It's provided by the little flap on the back of the air box--not provided on Yak-55's. I've had CJ's sans funnels and never had a problem with carb icing, which is a non-issue any way with a pressure carb, though structural icing/blockage could be, unless you're a blue sky guy like me. Get stainless exhaust, too, if you haven't already, to prevent fires, a real possibility with (guaranteed in time) perforated iron exhaust. The slip joints are a big improvement over clamps, too.
Which leads to the air filter problem. The spark arrester and intake screen do a lousy job of filtration. Surprising, given the typical unimproved and un-maintained airports the Russians and Chinese etc. use.
You probably know there are two CJ cowls, the early model with the intake on the bottom of the cowl and the later model with the intake on the front of the cowl. Which do you have? In both cases air filtration is minimal at best. You'll need to fabricate an adapter and maybe cut a foam or other type filter material to fit. Well worth doing and usually neglected. I don't know of a commercially available filter kit--Doug?--and have never seen a sanitary installation--nor have I ever done it myself! Goolsby's noted manifold pressure drop could be finessed with a diverter valve to unfiltered ram air--like some old Mooneys had--that could be opened in flight. Don't forget to retain proper drainage of the air box to prevent fuel collection and subsequent carb fires. I understand the M-14R (?) has fuel injection. I'm a little surprised no one here in inventive America has come up with an injection system a la R-985 etc. Lots of opportunities for real improvements.
I think cowl design is just about the weakest area on CJ's/-52's and begs for improvement. Craig Payne has picked up a few knots with modest revisions. I've often thought about changing the lower cowling mounts to allow re-shaping the after/lower portion to snug up closer to the fuselage. Po' boy that I am I've never been able to hold on to a CJ (or -52) long enough to do the job! The venetian blind arrangement on Yak-52TW's is terrible and entirely for cosmetic purposes, but some combination of cowl flap and/or augmenters and possibly some intake restriction (spinner/dish pan/iris?) should provide adequate (and probably improved) cooling while greatly reducing drag. Seal up the cowl bottom, too. Removing the intake vanes on a CJ is worth 10-15mph, but without them getting and maintaining proper temps is a real problem, unless, maybe, you live in Phoenix or Florida.
[img]cid:DB086B4D-209D-4E15-AABB-6B28E998A938[/img]
Jerry Painter
[img]cid:F7BCAD2B-CB00-4AED-BBA3-CE7A0FFAA5F9[/img]Wild Blue Aviation
425-876-0865[img]cid:62E4A43C-F4F3-4BBB-A15D-0E87C1E4D085[/img]wild.blue(at)verizon.net (wild.blue(at)verizon.net) [img]cid:E262E9D0-6703-47F9-BC02-BE331604C9EB[/img]
http://mysite.verizon.net/res0cs5r/index.html
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wild.blue(at)verizon.net
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| Posted: Sun Jun 11, 2006 12:14 pm Post subject: carb heat, filtration |
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Fiberglass is probably heavier than aluminum, but carbon fiber would be considerably lighter and easy to make compound curves. Lightspeed would be a big improvement. Go get 'em!
JP
-Original Message-------
From: PSalter(at)aol.com (PSalter(at)aol.com)
Date: 06/11/06 11:56:02
To: wild.blue(at)verizon.net (wild.blue(at)verizon.net)
Subject: Re: carb heat, filtration
Jerry,
Where do you find time to write your informative, interesting and long emails. I appreciate and welcome your opinions and ideas.
I ordered a stainless exhaust from Doug and will take delivery when he has a complete kit available. My cowl has the front intake. I have the foam brackett filter material I will look at the setup and see if I can figure something out. It seems a fiberglass duct would work well with the cowl intake.
I would like to have a new cowl built out of fiberglass. I have a friend building a Cozy a couple of hangers down that I would ask for help. I would prefer more of a Bonanza style cowl that could be opened for preflight with ease. Also, the vibration would be less of a problem with fiberglass as it would be much lighter. A friend in Houston is the constructor of the MX2. Last weekend I picked up the entire cowl and was shocked how light the carbon fiber is. I knew it was light, but shocked how light. Below is a picture of the MX2. The first plane went to a Red Bull race in Abu Dabi (or something like that) and was flown by Mike Goulian(or something like that).
I am surprised we are not all using Klaus Savier's (Lightspeed CDI) style of electronic ignition along with some style of fuel injection. Efficiency would jump along with reliability and a more power.
Thanks again!
Phil
In a message dated 6/11/2006 1:00:20 P.M. Central Standard Time, wild.blue(at)verizon.net writes:
Hi Phil--
As others have said, the "funnels" are intended to provide heated air to the carburetor. Keep in mind that, like a -52, CJ's have a pressure carburetor, so "carb heat" isn't really a necessity, but alternate air is. It's provided by the little flap on the back of the air box--not provided on Yak-55's. I've had CJ's sans funnels and never had a problem with carb icing, which is a non-issue any way with a pressure carb, though structural icing/blockage could be, unless you're a blue sky guy like me. Get stainless exhaust, too, if you haven't already, to prevent fires, a real possibility with (guaranteed in time) perforated iron exhaust. The slip joints are a big improvement over clamps, too.
Which leads to the air filter problem. The spark arrester and intake screen do a lousy job of filtration. Surprising, given the typical unimproved and un-maintained airports the Russians and Chinese etc. use.
You probably know there are two CJ cowls, the early model with the intake on the bottom of the cowl and the later model with the intake on the front of the cowl. Which do you have? In both cases air filtration is minimal at best. You'll need to fabricate an adapter and maybe cut a foam or other type filter material to fit. Well worth doing and usually neglected. I don't know of a commercially available filter kit--Doug?--and have never seen a sanitary installation--nor have I ever done it myself! Goolsby's noted manifold pressure drop could be finessed with a diverter valve to unfiltered ram air--like some old Mooneys had--that could be opened in flight. Don't forget to retain proper drainage of the air box to prevent fuel collection and subsequent carb fires. I understand the M-14R (?) has fuel injection. I'm a little surprised no one here in inventive America has come up with an injection system a la R-985 etc. Lots of opportunities for real improvements.
I think cowl design is just about the weakest area on CJ's/-52's and begs for improvement. Craig Payne has picked up a few knots with modest revisions. I've often thought about changing the lower cowling mounts to allow re-shaping the after/lower portion to snug up closer to the fuselage. Po' boy that I am I've never been able to hold on to a CJ (or -52) long enough to do the job! The venetian blind arrangement on Yak-52TW's is terrible and entirely for cosmetic purposes, but some combination of cowl flap and/or augmenters and possibly some intake restriction (spinner/dish pan/iris?) should provide adequate (and probably improved) cooling while greatly reducing drag. Seal up the cowl bottom, too. Removing the intake vanes on a CJ is worth 10-15mph, but without them getting and maintaining proper temps is a real problem, unless, maybe, you live in Phoenix or Florida.
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http://www.matronics.com/Navigator?Yak-List |
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