Tank size for OS La46 powered Brodak vector?

[kevin king]

I realize there can be different fuel consumption, but would like to hear what tank size to use on a Vector 40 with an OS LA 46? A 4.5 oz metal tank would fit easily, a 5 oz tank would require some grinding to get the tank to fit.

[GERALD WIMMER]

Hello I'm sure a 4.5 ounce would work fine if you are not working the engine hard and use a smallish venturi and low nitro .

[Jim Svitko]

There can certainly be variations in fuel consumption, depending on venturi, spraybar, nitro, etc.  I need 4.25 ounces on one LA 46, using 5% nitro, PA needle assembly, and a venturi of about 0.285.  In cooler air, I can get by with 2.5% nitro and still have plenty of power.  Another LA 46 I have needs 4.75 ounces so be prepared for such variations.

If your Vector 40 is not excessively heavy, and you do not need much nitro, 4.5 ounces should be enough.

[Jake Moon]

I learned the pattern on a Brodak Vector ARF with an LA 46 and used a 4-ounce plastic tank. That was enough for an extra 12 laps after the clover. I ran 5% nitro in 85 degrees and 85% humidity. The plane weighed about 46 ounces if I remember correctly.

[Peter in Fairfax, VA]

I have one LA 46 plane that takes 3.5 oz, another that takes all of 4 oz.  I use 5% nitro.

[Paul Taylor]

Also depending on the weather and altitude your mileage will vary.
I had to build a deeper tank to get more fuel on board.
You can certainly get a pattern in on 4.5oz. But as conditions change more fuel might be required.
I would plan on at least 5oz. What about a clunk tank?

[kevin king]

Thanks for sharing your experience every one. Much appreciated 👍 I will get both a 4.5 and 5oz tank. That will give me options.

[Motorman]

I have a 5oz on my Miss Kelly and it's plenty big. I don't fill it up all the way. I had a 4oz on it but it was cutting out too much to do the clover leaf.

I have a 4oz on a FTwister with LA46 and it's plenty big for that small plane. Does the pattern with lots to spare. Depends on how you run the engine too.

MM

[Tom Luciano]

I ran 5.5 oz. tank. I ran a tongue muffler opened up, large venturi, Pa needle. It took a little over 5 ounces on 10% at about 100' above sea level 12.25 x3.75 prop. Loved that setup!

Tom

[Neil Rogers]

Hi Kevin,

Rob and I always got by with a 4 oz. squishy plastic tank with our LA46s.  We used about 3.75 oz. for the pattern.  Rob used 10% fuel, while I used 5%.  We both used APC 11x5 props and 63 ft. eyelet to eyelet lines.  We found that our engines ran best with the small .40 size venturi and a Super Tigre NVA.  That choked the engine down a bit compare to the OS NVA, but provided excellent fuel draw with more than enough power.

[Steve Helmick]

Prop size matters a lot...the 12.25 x 3.75 APC is a LOT of load for the .46LA unless you use a big venturi, wads of nitro, and maybe open up the muffler outlet. Try the 11.5 x 4 APC, TT Cyclone 11 x 4.5, or something else that's less load.

If the weather is cold and barometric pressure is high, you might need to add a bit of Coleman fuel to your glow fuel mix. Up to 6 oz per gallon is ok, and it makes a huge difference in fuel economy/run time. 

A relevant fact about plastic clunk tanks is that many of them hold a little more than their nominal capacity. I've used several brands and been happy enough with them, but IMO they do require an annual replacement of the clunk tubing, which might then result in the need for some tank height tweeking due to re-assembly inaccuracies. Another disadvantage is that they just will not allow the use of a "cutoff loop" to help you end a flight a little earlier. It's not that big a deal for our 8 minute flight window...unless you have trouble starting. Knowing when to call an attempt can be critical.    Steve