stunthanger.com
General control line discussion => Open Forum => Topic started by: Larry Fulwider on April 21, 2010, 11:27:23 AM
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Do you check the volumes of tanks vs the advertised volume? It would be interesting if you could post what you have found from different suppliers and / or the same supplier with different sizes and shapes.
The most inaccurate advertised volume I have found is the Great Planes Viper 500 which comes with the Top Flite ARF Nobler. Embossed as 180 cc (and advertised as 6 oz) it is only 132 ml, or 4.5 oz. :o
Here is a somewhat random list of some tanks I’ve checked. (Not saying how the ones I’ve built came out compared to the plans!)
Viper 500 6 oz 4.5 oz
Du-Bro 406 6oz 6.0 oz
Brodak BH-489 Med Wedge ATF 4 oz 3.9 oz
Brodak BH-593 Profile 4.5 oz 4.3 oz
Methodology used: Each tank was filled, then fuel withdrawn through normal pickup with 2 oz syringe (and short 1” fuel line) calibrated in cc; syringe volumes withdrawn, noted and totaled. Results converted to ounces, and rounded to nearest .1 oz. Pessimestic estimated accuracy within 3 ml per tank.
The clunk tanks had all internal plumbing in place, including uniflow tube, with overflow in max fill position.
Larry Fulwider
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Probably, when a tank is designed, volume in ounces is converted to cubic inches, and then the plug (in my case) or the bending template is made. Actual volume might be a little less than calculated because (1) the overflow tube position leaves a little bit of air volume (2) the tubing displaces a small bit of volume.
It is normal to select a tank larger than necessary, and then measure the fuel load after several flights determine the correct amount.
Is that what everyone else does?
Floyd in OR
(driving directions to OR: "Follow the cloud".)
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Sullivan 4 ounce slant = 3.75 ounces
Dubro 4 ounce all tubes forward 4.25 ounces
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Perfect marketed two different size 3/4 oz long wedge tanks. HB~>
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Agree , agree!! I use quite a few of the Hayes plastic clunkers, 3,4, and 6 oz. They all hold quite a bit less than stated!!
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Agree , agree!! I use quite a few of the Hayes plastic clunkers, 3,4, and 6 oz. They all hold quite a bit less than stated!!
Ray --
Hey, I think those old clapped-out McCoys just use more fuel than you want to admit ::)
Sullivan 4 ounce slant = 3.75 ounces
Dubro 4 ounce all tubes forward 4.25 ounces
Interesting! The Du-Bro holds more than advertised? I think I have one, I'll check it also.
Larry Fulwider
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yes the Dubro does, I tworks out perfectly in a Viper Pylon racer, just enough fuel for a comfort margin when racing. also worked well in My Oriental, fits well, and just the right amount of fuel for my LA 46
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Interesting! The Du-Bro holds more than advertised? I think I have one, I'll check it also.
Larry Fulwider
The way I checked was to prop the tanks up with opening at the highest point, no plumbing. Filled them up and then sucked them dry with a syringe. What prompted it was I had a 4 ounce Sullivan in my Saito 62 powered stunt ship and it wasn't running as long as the 4 ounce Dubro in my old Score. Wasn't sure if it was the engine or tank. 1/2 ounce difference between the two told the story..