Cowl and Baffle Intersection Part 2

UnPossible · #1 03-23-2011, 09:18 PM

Well - I think I can see the light at the end of the tunnel wrapping up my baffles. However, this afternoon I had one of those "oh ****" moments.

When I have been taking my cowling on an off, I am shifting it forward to clear the baffles, then sliding it back into place. However, when the prop / spinner is installed, I won't be able to shift it nearly as far forward.

Below is a picture of my left air inlet baffle. Note the front edge of the baffle butts right up to the front edge of the K&N filter (meaing I can't really trim this back any further).

Right now, the cowl overhangs the front of the baffle. I took some rough measurement, and it appers that I will need to trim the lower cowl at the blue line to clear the baffle.

My questions are....

1) Any issues with trimming the cowl to the blue line or a bit more?

2) What gap (between the cowl and the baffle) should I shoot for to make taking the cowl off as easy as possible and still seal well? On the right side, the gap is ~1/8"... is that good or should I shoot for a larger gap?

Thanks again,
Jason

KayS · #2 03-24-2011, 08:42 AM

thank you for your pictures... i'm at the same stage as you and i asked the same question. the answer was to shoot for a gap of 1/2" to 3/4" (i aimed for 1/2). this should give you enough room for easy removal of the cowling and still give you a good seal.

after cutting the ramp to get the 1/2" gap, i was running out of space to accommodate the filter. i think i will rivet an angle to the forward edge of the ramp (like in your pic) to gain some forward space and compensate this by trimming the cowl lip a little bit. i don't feel that it would be a problem to trim back the cowl at your blue line as long as there's still enough space left to secure the seal material and it still looks smooth.

suggestion... i don't know if it was your intention to cut the hole length of the blue line you've been drawing. i would keep the side part where the nutplates are to keep the aft most nutplate. this seems to be a high stress area so only two screws/nutplates are maybe not a good idea.

question: what's the purpose of that hole in the right ramp? you want to enlarge it for the heater scat tube flange?

again... thanks for the pictures, good timing.

Kay

Flying Scotsman · #3 03-24-2011, 11:28 AM

I have *exactly* the same question...my filter/snorkel is aft about as far as it can go, and I hit the same *aha* moment as you. I'm guessing it's going to mean trimming the cowling quite a bit (and the issue of making the two inlets look the same or at least not all stupid-looking by being vastly different may mean trimming the *other* side, too).

Anyone here have any pics or comments to help us out here?

UnPossible · #4 03-24-2011, 12:46 PM

Over lunch today, I carefully measured where I would need to trim the cowl for

1) Baffle Clearance (blue line)

2) 1/2" Baffle Gap (red line)

As you can see, there will not be much of the front cowl inlet left.
I am planning on calling Vans later this afternoon to ask if there is a minimum depth needed at the cowl inlet, and what the ideal baffle / cowl gap should be to get the cowl on and off.

I would love to hear from anyone that has already tackled this step.

Thanks,
Jason

shuttle · #5 03-24-2011, 02:22 PM

Jason,
On a slightly different tack, I angled my left side baffle in a bit so that it aligns more closely with the inlet. The baffle seal attached to the lip on the lower cowl does not mate up very well in the outside bottom lefthand corner. I wanted to minimise the gap. (the equivalent of where the curved fillet sits on the other inlet ramp).
Steve

Flying Scotsman · #6 03-24-2011, 02:25 PM

Why are you looking at 1/2" gap? Isn't there a detail on the plans that shows something like this:

______________ Aft Edge of Cowl Inlet
------------ Air Seal Fabric
______________________ Air Ramp or Side Baffle

Check Figure 2 Section A-A on p. OP-9 for this depiction and the Note that describes it.

UnPossible · #7 03-24-2011, 02:41 PM

You are correct that the plans does not show a large gap.....

However, reading thru VAF and speaking with a few builders, they seemed to recommend a larger gap so that you can get the cowl on and off without scratching up the paint.

Flying Scotsman · #8 03-24-2011, 02:44 PM

Quote:

Originally Posted by UnPossible

You are correct that the plans does not show a large gap.....

However, reading thru VAF and speaking with a few builders, they seemed to recommend a larger gap so that you can get the cowl on and off without scratching up the paint.

Ah...makes sense...

UnPossible · #9 03-24-2011, 05:01 PM

FYI - I spoke with Vans this afternoon and they recommended a gap in the order of 1/4" to 3/8"...... I am going to shoot for close to 3/8" and go from there.

miyu1975 · #10 03-24-2011, 08:49 PM

OK...I know this is off topic but I am almost at this stage as well. I just starting baffling and I have the same Vans pink cowling. Was wondering though, do I need a prop before I can start my fitting of the cowling? I don't currently have my prop and won't for a while..