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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
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Posts: 391
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 Posted Friday, May 8, 2009 @ 04:28 PM
Here is the latest progress on the new intake for N2188.
This is the new bottom section. I redesigned the bracket to move the carb as far back and high as possible to reduce interference with the cowl as much as possible.
Here is a look at the new bracketry design for left and right side. The only drawback to the design is that you must have the engine off the fuselage to mount and/or remove the bottom intake tubes. Also note the need to notch the Diehl case to clear the brackets.
 
This is the whole intake in position. It still needs to be final welded. The down-tubes are in sections to make it easier to assemble it through the baffling walls. I can also make modifications to individual sections without rebuilding the whole thing.
 
I also made the modifications to fit the starter and made a new fiberglass cover/bowl using a foam mold covered with duct tape as a mold release.
 
 
Gascolator and fuel lines are next. Then I think I will start recovering the wings and control surfaces now that the weather is warming up.
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Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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Collin
General
Gender: Male
Location: McMinnville. Oregon
Registered: Oct 2006
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Posts: 711
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Posted Monday, May 11, 2009 @ 11:51 AM
Hi Dann,
Your intake looks first class!
Collin
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
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Posted Monday, May 11, 2009 @ 04:15 PM
Nice work Dan,
Looks fantastic.
Don't want to be nitpicky though but that 90 deg bend at your carb, is going to create an intake restriction or cause adverse turbulence, in the intake as a low pressure area is created around that sharp corner ?
Maybe in practice its not a big deal but it looks like a potential place for problems on an otherwise perfect install.
Anyone else have an opinon on this?
Respectfully,
Ray
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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
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Posts: 391
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Posted Tuesday, May 12, 2009 @ 01:28 AM
That could certainly be a big issue, and I looked around at a lot of different designs. I think the big question is will there be an even mixture for each side for the full throttle range. There is a manifold system from Great Plains that has this 90 degree angle, but I have not been able to find any documented cases of it being used with an AeroCarb. Sonex (AeroVee) mounts the AeroCarb in updraft mode straight down from the "Y", and also rotates it 90 degrees, but the AeroCarb would not fit like that here.
It could certainly be possible to cut in some tube sections to form a radius or angle at the corner. The original Rectimo manifold has a cast piece at the junction that has slightly rounded corners. Will even a small angle or radius help the flow? Or is the turbulence necessary for better fuel mixing?
Manifolds are a black art. This is still a work in progress until it proves itself with extensive ground tests. But breaking the 90 degree angle a bit is probably a good idea. Thoughts/comments.
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Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
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Posts: 583
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Posted Tuesday, May 12, 2009 @ 01:45 PM
You have some nice radiused bends further up, you should just do another at the carb, and if it puts the carb too far forward just cut the pipe part way though the radius and weld the plate on there.
You may have a slightly oval pipe opening but I think that is preferable to the sharp bend and the low pressure area it will create with sharp corners.
I'll bet you are getting anxious to get in the air since you are almost done. 
Ray
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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
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Posts: 391
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Posted Saturday, May 8, 2010 @ 02:14 AM
Well, after looking at the new intakes for a while, I decided that the air path was too complex at the top, and might contribute to uneven fuel distribution. So I rebuilt the top sections to be a smooth curve into a small chamber over the intakes. Sonex and a few others have success with a similar design, so I thought I would give it a try.
Here the new tubes are being fabricated. The chamber is formed by splitting a tube...
and welding in a piece of 16ga sheet. It's just tacked in here.
They are a snug fit under the new cowl. But I think they will work better. Only time and a lot more work will tell.
I'm beginning the fabric re-covering process and will post new pics this weekend.
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Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
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Posts: 583
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Posted Monday, May 10, 2010 @ 03:10 PM
Looks great.... Hopefully you will get it all done and flying by 2011 so you can join us for the Fournier Fly-in.
Just an asside, I am still using the Aerocarb and it seems to be working just fine now that I know how to use it.
I even hand propped it a few weekends ago and it started right up after a couple flips.....nice!
I like the idea of being able to adjust mixture and so have not switched to the Zenith.
Once I get my extra CHT and EGT probes installed for the MGL engine monitor I will see whats really going on and be able to play with the mixture a bit.
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Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
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dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
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Posts: 391
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Posted Tuesday, May 11, 2010 @ 11:04 AM
I'm glad to hear the Aerocarb is working OK. Are you using the fuel pump at all?
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Dann Parks • RF4D #4051 N2188 • now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
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jb92563
Second Lieutenant
Gender: Male
Location: Lake Elsinore, CA, USA
Registered: Mar 2007
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Posts: 583
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Posted Tuesday, May 11, 2010 @ 02:41 PM
No, I have only ever used the fuel pump once and that was on the ferry flight home when the engine stumbled for a couple seconds.
I cycled the throttle and turned on the pump, but in retrospect I think it might have been some dirt or ice in the carb.
The way my pump is connected it is just an 18" loop and I think is pretty much useless as plumbed.
I am thinking that the benefit of the Zenith carb is the float chamber and a reservior of fuel very close to the intake for those moments of pitch or inverted that cut off the tank supply.
I think you could do the same thing with the aerocarb by providing a reservior at the carb fuel intake. Then a fuel pump to the reservior could actually be usefull with a return line/vent to the tank so you can not over pressure the carb or cause any fuel leakage.
My stop proceedure is to close the fuel valve and full lean the carb which effectively shuts off all fuel flow to the carb and the engine stops.
Doing this ensures no fuel dripping and makes starts a 1-3 flips process with no flooding, since you stopped the engine via fuel starvation, not the ignition switch.
You do however have to remember to shut off the ignition switch as well afterwards since the consequences of not doing that could be dire.
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Ray
RF4D #4057 N-1771 Rectimo 1400cc
http://picasaweb.google.com/jb92563/FournierRF4D
http://www.touringmotorgliders.org
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