Van's Air Force
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Inlet ducts pictures wanted
- Thread starter Webb
- Start date
Rick6a
Well Known Member
Sure. The left photo shows the ramps installed to support the vertically mounted carburetor on the O-320. The photo on right shows the ramps supporting the horizontally inducted IO-360. As you can see, the placement is virtually identical.....ergo....engine config/type is generally a non-issue. I'm sure there are any number of ways to install the duct ramps and others may have approached the task differently. I interpreted the instructions by butting the ramps up to the intake flanges that are molded into the upper cowl and then using West epoxy to lay in 2 layers of cloth centered between the upper surface of the parts. There is enough room to reach in there and apply the cloth. Later, a bit of filler was added to the lower area that is open and exposed to view, sanded smooth. The aft flange of each ramp was simply bonded into place on the upper cowl. The idea of the ramps is to provide a less turbulent, more efficient airflow over the engine. Later, when the engine baffles are installed, you can either position and install the baffles so the rubber seal is outboard of the ramps as the telltale "skid marks" in the left photo illustrate, or shape the baffle and its seal to conform to the curvature of ramp as I did with the ramps on the right.
Like those before me, I later glassed in the exposed areas of the ramps as suggested, it is very easy to do, but cannot report any perceived difference in performance, but then I've never really tried to document any before/after results. Other builders report a significant improvement. The following caveat is part and parcel to the RV building experience: As always, YMMV.
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Thanks Rick
I appreciate the pics. Have to tell you that I now understand why they call the darn things baffles. I let loose a string of profanity today that would have made a sailor blush. Kid from next door heard me and told me I cursed better than his dad (lol). Vans instruction on the inlet ducts are weak. Called them today and Joe was stellar with help.
Bottom line, I'm at the end of building and feel almost manic to finish except I'm tired of building. Joe was an inspiration.
I really appreciate the photos. They answer the visual questions I had.
Webb
N32SW
I appreciate the pics. Have to tell you that I now understand why they call the darn things baffles. I let loose a string of profanity today that would have made a sailor blush. Kid from next door heard me and told me I cursed better than his dad (lol). Vans instruction on the inlet ducts are weak. Called them today and Joe was stellar with help.
Bottom line, I'm at the end of building and feel almost manic to finish except I'm tired of building. Joe was an inspiration.
I really appreciate the photos. They answer the visual questions I had.
Webb
N32SW
Wow, I'm at the same point doing baffles and cowling. It's such a slow process, (fit, disassemble, attach, etc....) that I'm starting to look for work around the house to do instead of working on the plane. I probably just need a break.
Here's mine...
Hi.
I've a Superior IO-360 horizontal induction too, and here's my set up.
The ramps are first clecoed in place, then glued in place with industrial glue, then gaps and edges where filled with flox and sanded smooth and finally the ramps where glassed in.
As you can see, I've added inboard "sidewalls" to the ramps to stop airleaks.
I've done this because folks in this forum recommended it. (makes sense to me too)
The sidewalls is simply small triangles made from foam, filled with microballons, glued and fiberglassed in place.
Hope this helps.
Hi.
I've a Superior IO-360 horizontal induction too, and here's my set up.
The ramps are first clecoed in place, then glued in place with industrial glue, then gaps and edges where filled with flox and sanded smooth and finally the ramps where glassed in.
As you can see, I've added inboard "sidewalls" to the ramps to stop airleaks.
I've done this because folks in this forum recommended it. (makes sense to me too)
The sidewalls is simply small triangles made from foam, filled with microballons, glued and fiberglassed in place.
Hope this helps.
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IMAGE SIZE !!
One such place is www.Imageshack.us - a site that is about the easiest I've ever seen. They have a 1MB per picture limit, so if your image is 3MB and two feet in width you'll need to reduce it first. Once you have the picture at the size you want (a nice size for the forums is 700 pixels wide), go to their site. You'll see the following screen.
One such place is www.Imageshack.us - a site that is about the easiest I've ever seen. They have a 1MB per picture limit, so if your image is 3MB and two feet in width you'll need to reduce it first. Once you have the picture at the size you want (a nice size for the forums is 700 pixels wide), go to their site. You'll see the following screen.
AO Frog - I like the side enclosures. I'll wait until I see how the baffling meets the ducts to see if I want to go that extra step. It would make it stronger. I may do it anyway since I have to glass in the joints. What the heck - just a bit more time in the building log.
Webb
N32WW
Webb
N32WW
Take pride in your work here
This is an area where your individuality, care and precision can really make a difference in performance and serviceability. When I originally put the inlet flow smoothing panels inplace I did not close in the sides. After quite a bit of flying I went back and closed in the sides (all four) with blue foam and sealed over them with fiberglass (I use EZ-Poxy brand from Aircraft Spruce). In shaping the foam I cut it back under as it approached the cowl surface before the fiberglass operation so the baffle seal would be allowed to lay flat against the upper cowl in this area as it did before the plugs were added. I did this as a speed mod thinking that air tumbling off the edge of these "ramps" curling back on the underside had to create drag. My flight test revealed no change in speed as a result of this mod so I left it. When you install the upper cowl with the ramps plugged be sure to stick you hand in the inlets and guide the rubber seals into proper position (not binding with gaps in the seal).
I tried extensive baffling in the lower cowl and came up with a configuration that gave a 4 kt increase but most of the changes actually slowed the plane down. My point is, this is an important part of building the airplane for engine health and airplane performance and you should focus on creating the best installation possible instead of letting it drive you to anxiety.
Bob Axsom
This is an area where your individuality, care and precision can really make a difference in performance and serviceability. When I originally put the inlet flow smoothing panels inplace I did not close in the sides. After quite a bit of flying I went back and closed in the sides (all four) with blue foam and sealed over them with fiberglass (I use EZ-Poxy brand from Aircraft Spruce). In shaping the foam I cut it back under as it approached the cowl surface before the fiberglass operation so the baffle seal would be allowed to lay flat against the upper cowl in this area as it did before the plugs were added. I did this as a speed mod thinking that air tumbling off the edge of these "ramps" curling back on the underside had to create drag. My flight test revealed no change in speed as a result of this mod so I left it. When you install the upper cowl with the ramps plugged be sure to stick you hand in the inlets and guide the rubber seals into proper position (not binding with gaps in the seal).
I tried extensive baffling in the lower cowl and came up with a configuration that gave a 4 kt increase but most of the changes actually slowed the plane down. My point is, this is an important part of building the airplane for engine health and airplane performance and you should focus on creating the best installation possible instead of letting it drive you to anxiety.
Bob Axsom
