CG Fuel Tank
07-07-2005, 02:18 PM
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CG Fuel Tank
I am just finishing an Excellron 90 and because I am using a 4 stroke and the fuel tank provided in the kit is totaly inadequate, I purchased a dubro tank, wrapped it in fiberglass insulated tape for strength, and since I am using this for pattern flying, I wanted to put it over the cg point. My question is this:
What is the best way to mount this tank in the plane. There is plenty of room at the cg point , can I just run a couple of beams across the fusilage and then use foam and velcro tie downs ( I love to use velcro tie downs over rubber bands). How strong does it need to be for a 16 oz tank?
I am open to any suggestions. Funny thing is I have built 5 or 6 planes and have always had the fuel tank in the nose section Which makes it easy to tie the tank down.
Thanking you all in advance
What is the best way to mount this tank in the plane. There is plenty of room at the cg point , can I just run a couple of beams across the fusilage and then use foam and velcro tie downs ( I love to use velcro tie downs over rubber bands). How strong does it need to be for a 16 oz tank?
I am open to any suggestions. Funny thing is I have built 5 or 6 planes and have always had the fuel tank in the nose section Which makes it easy to tie the tank down.
Thanking you all in advance
07-07-2005, 03:55 PM
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RE: CG Fuel Tank
Fuel tanks are placed close to the engine to maximize fuel delivery. I don't know for sure, but I suspect moving a fuel tank aft to the CG may cause you some problems, particularly if it's a long haul from tank to carb.
DaveB
DaveB
07-07-2005, 05:58 PM
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RE: CG Fuel Tank
Hi Walfam,
I wrap my tanks in medium density foam and secure with zip ties to 1/4" balsa cross braces so it is easier to remove when necessary. Seems to work fine without foaming, I think the amplitude of the vibrations may increase with distance from the firewall anyway? (I know someone will probably jump in with amplitude vs frequency in the foaming equation)
DaveB has identified that unless you have a pumper type motor/carby or positive crankcase pressure you may have difficulty with fuel flow when the level in the tank gets low. I would first try it without going to hassle of new motors or crankcase taps etc.
One tip I will pass on that I read some time ago, from (Minn?), and have since followed, is to buy a length of the brass fuel tube from your LHS and run the metal tubing from tank through the fire wall. This way all silicon tubes are where they are easier to see and more importantly where when they split the fuel doesn't fill the fuse. I once spent ages filling my Dynaflite PT19 and only stopped when the puddle of methanol reached my knee!!![:@]
Cheers,
Colin
I wrap my tanks in medium density foam and secure with zip ties to 1/4" balsa cross braces so it is easier to remove when necessary. Seems to work fine without foaming, I think the amplitude of the vibrations may increase with distance from the firewall anyway? (I know someone will probably jump in with amplitude vs frequency in the foaming equation)
DaveB has identified that unless you have a pumper type motor/carby or positive crankcase pressure you may have difficulty with fuel flow when the level in the tank gets low. I would first try it without going to hassle of new motors or crankcase taps etc.
One tip I will pass on that I read some time ago, from (Minn?), and have since followed, is to buy a length of the brass fuel tube from your LHS and run the metal tubing from tank through the fire wall. This way all silicon tubes are where they are easier to see and more importantly where when they split the fuel doesn't fill the fuse. I once spent ages filling my Dynaflite PT19 and only stopped when the puddle of methanol reached my knee!!![:@]
Cheers,
Colin
