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Fuel line access behind cowl

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Old 05-18-2004, 09:41 AM
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Gringo Flyer
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Default Fuel line access behind cowl

I am finishing up my first kit a Funky 40 by CAModels. It was a lot of fun, a bit challenging but I took my time and while not perfect I learned a lot and it looks great. I am about to cut the fiberglass cowl and I am not sure how to leave access to the fuel lines. How do you make neat looking cuts and still leave access to the fuel line to fill the tank?
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Old 05-18-2004, 09:46 AM
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Default RE: Fuel line access behind cowl

You can just use a fuel dot. The easiest way is to just drill a hole in the cowl where the fuel dot goes, and install the fuel dot in the fuse side.
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Old 05-18-2004, 03:01 PM
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Default RE: Fuel line access behind cowl

Hey Gringo V - I just finished scratch building the cowl for my project and finally came up with a way to fuel/de-fuel without a lot of fuss. You'll need to look at the pictures to figure out what the heck I'm talking about.

I took the fill line and took it to the top of the fuslage and installed a Slimline fuel dot. I also have a clunk on this line in the tank and use it to de-fuel as well.
I then needed to get the muffle pressure up to the tank, but also wanted to be able to disconnect this line when filling so I didn't fill the muffler or cylinder on the engine since it's inverted.

So here is what I did. I ran the vent line down from the tank to a nipple that goes through the cowl (I also added a filter in line to keep crap out of the tank). Ran another line that goes from the muffler pressure nipple to another nipple next to the other one. I then took a small piece of hose and looped it from the two outside nipples to make the complete circuit. Now when I fuel, I just slip the hose off one side and when the tank is full it comes out into a small bottle to catch the excess (with the cost of fuel I'm trying to conseve every drop ). Since the pics were taken I have moved one of the nipples further away so I got rid of what looks like a kink in the outside loop line.

The link is to a set of pictures of the build of my Sig 4 Star 120, I hope the link takes you to the first picture I had in mind. Hope it helps a little...........

[link=http://groups.msn.com/PuttsRCHomePage/sigfourstar120build.msnw?action=ShowPhoto&PhotoID=1247]Fuel line route through closed cowl.[/link]
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Old 06-03-2004, 04:31 AM
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Default RE: Fuel line access behind cowl

ORIGINAL: CRFlyer

You can just use a fuel dot. The easiest way is to just drill a hole in the cowl where the fuel dot goes, and install the fuel dot in the fuse side.
I totally agree. Simple, easy, and very clean looking. No dangling hoses. I get mine from Central Hobbies.
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Old 06-03-2004, 03:39 PM
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Default RE: Fuel line access behind cowl

how bout on the bottom glue a piece of wood there and drill a hole and put a kwick fuel valve there? thats whats on my RV-4
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Old 06-03-2004, 04:18 PM
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Default RE: Fuel line access behind cowl

the quickfuelers always sound like good idea, but if you get any dirt in them they leak and cause the engine to run like crap.
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Old 06-03-2004, 06:12 PM
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Default RE: Fuel line access behind cowl

To cut and finish up with the best looking job, use a Dremel type tool. The Chinese clones are so cheap now, they're a must have for everyone even if you only use them for cutting cowls on ARFs.

Refuelling a cowled engine? Use a fuel dot in conjunction with a double vented tank.

You can use a refuelling valve (DuBro or Great Planes), but apart from being 10 times more expensive and prone to leakage through spring failure or dirt in the seal/seat, they require sub-structural support when mounting in your average cowl due to the force used when inserting the refuelling probe into the valve. Then the bloody fuel probe only fits its particular brand of refuelling valve, so it becomes a nuisance if/when you have to refuel ordinary silicon tube lines from your jug.

My preference for cowled engines is to stick with the relative inexpense, utility, universality and simplicity of a fuel dot.
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Old 06-04-2004, 03:45 PM
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Default RE: Fuel line access behind cowl

thanks, I was leaning toward the quick fueler by GP I thought it would be the best despite the price. SInce you all insist, I'll go with a Dubro fuel dot, thanks

By the way, any hints on getting the cut right on the cowl. My plane came with a clear cowl to practice on and I cut it out. It pretty much looks like garbage. I think I can do better with the real one now that I have a better idea of where to cut. Any ideas on how to get more accurate cuts. (I do have a dremel)
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Old 06-04-2004, 11:29 PM
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Default RE: Fuel line access behind cowl

We don't insist, but you'll be pleased you did. I have two brand new DuBro Kwik-Fill refuellers lying unused in my building accessories box.

BTW, if you can find an alternative, pass on the plastic DuBro fuel dots. There is a company here in Oz which packages inexpensive aluminium fuel dots under the brand name TY1. You might be able to find similar repackaged over there. Much nicer than the plastic DuBro units. See the images accompanying this post depicting the aluminium fuel dots and TY1 company (who distributes them in Oz) logo.

As for cutting the holes in your cowl here's how I do it.

1. Use the clear overlay supplied to accurately mark out the outlines/positions with either a chinagraph pencil or text marker pen. Take your time and mark accurately. Check your work. Remember "measure twice, cut once!"

2. With a sharp 1/16" drill bit, drill small holes in the clear plastic overlay just inside the outlines of your engine head, intake and exhaust exit (if elongated 2 stroke type) to form an outline pattern. For round holes such as for N/V etc, drill a hole in the approximate centre. Mk I Eyeball accuracy will do for the latter.

3. Place the drilled clear overlay over the cowl & secure it with tape. Cross-check it for positiioning & accuracy. Using a chinagraph pen or text marker, mark the outline points & hole centres on the virgin cowl. Remove the clear overlay and reposition the cowl in position on the fuse before drilling or cutting for an intuitive Mk I Eyeball check to gauge that you've marked correctly and everything is approximately where it should be. Doing it this way rather than fully cutting out the clear overlay to transcribe is just as accurate and saves you spending the time and effort of doing the job twice.

4. Once you're happy everything is positioned as it should be, begin by drilling small holes in the virgin cowl with a 1/16" or 1.5mm drill bit, positioning them about 1mm inside the dotted outline you will have marked for your typical two stroke exhaust cutout or engine/intake outlines. Enough to guide you to cut an accurate outline with the Dremel cutting wheel is sufficient. For round holes necessary for N/V, 2 stroke silencer bolt access, fuel dots etc, just drill small 1/16" holes where you've marked as centre of those intended holes.

5. Now using a the Dremel and a cutting wheel, with considerable care open up the outlines by cutting lines leaving about 1mm margin which you'll chamfer and shape to final finish later. Open up the 1/16"drill holes for intended round holes initially with a larger 3mm (3/16) or 4mm bit.

6. Now you've gotten the outlines and holes cut and placed, you can set to straightening lines, shaping corners, curves and opening up those holes to perfectly sized round with grinding stones and wheels. When you're finished, it should look like a master craftsman has been at work. The key to a good looking cowl cut-out job is patience and care. Remember to cross-check before you cut & grind. Importantly go easy. Take 'little bites'. If in doubt, check again, and again if necessary. You can always take more off/out, but you can't put it back.

Have fun. A little extra time taken during initial assembly to cut out the cowl accurately will repay you with the pleasure of many hours of reliable service and longevity.
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Old 06-05-2004, 06:26 AM
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Default RE: Fuel line access behind cowl

I get tetra dots from central that are about $5 per pair. THey work fine.

As for the cowl cutting, I also use a Dremel. For cutting perfect holes to fit the fuel dots I like to start by drilling a small 1/6th inch diameter hole. Then I use a cone bit on my dremel to plunge into the hole. The further you plunge the bigger the hole gets. Just plunge in far enough to get the right diameter of the fuel dot housing. Leaves a perfectly round circle and has a very nice neat look to it.
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Old 06-06-2004, 07:50 PM
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Default RE: Fuel line access behind cowl

coomarlin

The Tetra dots are great. The TY1 ones are very similar.

I mentioned TY1 because Tetra accessories are difficult to source in Oz. Because of their local pricing, they're usually used only by the 'spare no expense' or label 'junkies'. Good call as Tetra is probably much easier to source in the US. TY1 dots here are only AUD$5 a pair. Tetra are 3 times that locally, if one can source them.

I position and shape my round holes for the fuel dot mount, exhaust bolt and N/V accces exactly as you've described.
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Old 06-06-2004, 08:18 PM
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Default RE: Fuel line access behind cowl

sigrun, thanks for the advice on cutting the cowl. As far as the dots "over there" for me means Argentina and not the US. If you count out the pacific ocean and Chile (we used to live there too) I guess you and I are neighbors. There are a few Argentine manufacturers of various RC stuff and I will see if they have the a national brand, other wise I'll have some visitors bring the Dubros in for me.
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