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Jabiru FWF Top Cowl trimming
Gents, I have just installed the lower and top cowls (JAB USA) temporarily, initial impression was "Crikey mate" I need a 10 " Spinner, however I believe I can trim the top cowl at the front where it runs across the intakes and around the prop shaft to lower the front of the top cowl. This would require the top cowl forward bottom edge to have about an inch trimmed off. Before I hook in has anyone else trimmed this much? This makes the nose of the cowl 9 inch round, currently it is 9 inches wide and 10 inches tall.
Replies to This Discussion
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Permalink Reply by John Burns on
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Mine was fine at the spinner, but everything else needed serious trimming to fit. The bottom cowling was fitted first using half the donut spacer refereed to in the instructions. The rear of the bottom cowling needed extensive trimming to fit the fuselage then the top cowling needed trimmed from zero to about an inch as it went from front to rear. Then I trimmed a curve in the top cowling to clear the windscreen. As I put in a previous post my biggest challenge was the fact that the engine mount hardware and spacers are installed different top vs bottom. Once I fixed that the cowl fit better. I still have more trimming and fitting to do to make it just right, but it fits now.
I have a 9.5 Inch Aluminum Spinner with the Whirlwind Prop. It looks like I have about a 1/4 inch of flat cowling above and below the spinner.
I will see if I can find a good nose on picture.
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Here are the pictures of mine. No trimming at the spinner area of the cowl, but again I have a 9.5 inch aluminum spinner.
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Permalink Reply by Scott Matthews on
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Awesome, yes that is what I have. If I just leave it as is it would need a 10 " spinner to look nice in the vertical but the spinner flange on the cowl is only 9" wide. I plan to knock an inch of the front and make the spinner flange round. I also want the top cowl to follow the glare shield angle down and not stick up. Appreciate the photos thanks
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Nice, what engine is in there?
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Permalink Reply by Jay Carter on
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Scott, Don't get carried away trimming the cowling. Fit the bottom cowl front and rear. Do not trim the forward end of the lower half. Sit the upper half place. If the front needs lowered, pull it down over the lower half till it is in place. You will trim to make the top half to lay in the lower half overlap. If you lower the top half other than that how will the cooling ducts be installed? Cowlings are not the easiest parts to install. Remember, the engine is offset, so the cowling is offset too.
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So I jumped in an first thing was to make the front spinner ring round, as it comes its about 10" high and 9" wide, so I chopped an inch off the front of the top cowl and tapered it to the rear. This worked a treat, also made the cowl align with the angle down of the glare shield rather than poke up and look like the engine has up thrust. With the standard Jabiru plenum chambers I now need to close the air intakes in the cowl, they are way to big. Going well, lowering the cowl still left room for the oil dip stick starter and plenum chambers.
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Looking good.
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Permalink Reply by Carlos Sa on
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Scott, thanks for the link you posted on my photos page.
Judging from your photos, the cowling changed a lot since I received mine - but it seems the fit did not improve...
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Same cowl I think
, I just cut and inch off the front to lower it down rather than build it up like you intend to.
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The shape of the air intakes is different (but they did not change the air ducts?!?)
Compare the vertical distance between the top of the air intake and the top of the flat section behind the spinner. On my cowl, this is ~ 7 cm, while yours seems to be much less than that.
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What a pain, can you drop the whole lot, both top and bottom cowls, down?
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