Is 6oz enough for a LA .46

[Paul Taylor]

Two questions:

Should a 6oz tank work for a LA .46 and ARF Nobler to do the pattern?

And by looking at the photo blow should I drop the tank to line up with the spray bar?

[Mark Scarborough]

Paul
In my experience ( and that of several guys flying LA 46 in the NW) I typically expect to use between 4 and 4 1/4 ounces for the pattern. I burn Powermaster GMA 10 22 fuel, use an APC 12.25 x 3.75 prop and spin about 9800 rpm for take off. It has been a really solid setup.
so simple answer, yeah I think 6 oz will get you there ,, with time to spare.

as to the tank. If you are plumbing that clunk with uniflow, then the uniflow outlet is what you want aligned with the venturi ( more or less) then adjust for equal performance insides and outsides. There are several good threads on clunk tanks and the varied ways to set them up for uniflow.

[Will Hinton]

Paul, my experience mirrors Mark's.  Six oz. filled up will get you tired, and the 4.5 oz is about perfect.
Will

[Jerry Leuty]

I have a LA .46 on a profile Cardinal that I have been flying for several years. I usually run a 11-5 Pro Zinger prop. I  have found that at 650 feet above sea level here in north Texas that about 3.5 ozs. is more than enough fuel to do the pattern. I use 10% or 5% nitro and 29% castor, what we call Super Stunt fuel. I use a clunk tank set up on a two line system with pressure from the muffler. It  always burns all the fuel. I have thought about getting one of the free flight timers to mount on the ship so the fuel would be cut off somewhere around 7 1/4 minutes or so. Then when I go fly in the higher elevations I am not concerned about over runs. I flew in Albuquerque last August and the first flight ran over by 6 seconds. I did receive a fair judge and lost landing points. It is strange that one flight will run short of fuel and by adding just a half ounce of fuel the engine will run another 2 minutes. Really when you stop and analyze a flight there are a lot of factors that have to work in your favor in order to score well. And that is just the mechanical and atmospheric part not to mention the subjective judging that we all do and get. Here in Dist. 8, we the Dallas Model Aircraft Association, give out an award in Oct. for the Dist. 8 Championship. It is given to anyone making the most scoring in the district contests. Dale Gleason has won it the past several years now. It takes lots of money and time to travel to the out of state contests, the equipment has to work well, you have to fly it well, and place. Not an easy feat by any means. I have seen men take on this challenge in past years and win the coveted trophy only to of accomplished that and we never see them again. Trophy hounds! If this is you then you have my blessings. Personally I had rather compete and let you take the trophy home with you and to of enjoyed my day of flying. Anyway go fly the engine and experiment with different fuel levels. I'll bet that 6 ozs. of fuel will get you a 10 minute run.

[kenneth cook]

         I'm puzzled at the economy the .46 gets. I found this to be true from fellow club members as well. I have the LA.40's which barely make the pattern for me using 4 1/2 oz's. I have to tilt the nose of the plane up and outboard to get every possible air space filled with fuel then I need to run slightly lean to get through a pattern. This has me running for the lines on startup and meticulously counting laps as to not dare put a extra in there or I won't make it. I start running out of fuel as I just enter the cloverleaf. My Fp.40 is using 5 oz's to get through the pattern. I'm just shocked as to why the larger displacement doesn't use as much fuel. Ken

[Jerry Leuty]

Some of your quest may be in the prop. If you run a 6 pitch prop it will require a much richer needle setting just to slow the ship down a bit. FPs are bad about run aways. Another thing is what altitude are you flying at. Try  running a leaner prop of say about a 4 pitch and lean the engine out a bit more to lessen fuel consumption. Here at 650' above sea level I can run a little over 3 ozs. of fuel of either 5 or 10% and still get an over run on time. Also you might try using 25 to 29 percent castor oil content. Synthetic oil will burn off thereby causing greater fuel consumption and a leaner run. With the heavier oil content the engine will naturally slow down a bit on the RPMs.

Jerry

[Paul Taylor]

Thanks guys for the input. I will have to go hunt for the thread on the tanks. I plan on running 10/22 on muffler pressure.
Ken to your issue. Could venture size matter? I am just guessing.

[Mark Scarborough]

I think you will find the difference between the 46 and the 40 has to do with timing.
as to the LA 46, at least TRY the 12.25 x 3.75, it really mellowed the engine . previously I , we , had problems with the needle and fuel consumption being erratic. after the prop change the engine became very well behaved..

[kenneth cook]

        As stated Paul, the Fp if not set up does suffer from the runaway syndrome. I'm using the Apc 10.x4.5 prop Randy Smith tongue muffler drilled out slightly and the large venturi that is offered from Tower Hobbies. I haven't had it runaway but I was thinking on the same lines as you stated. I never tried a smaller venturi. Dan though stated that using more fuel is keeping things cool. As for the La engine I'm using the same prop and stock venturi and it just seems to be a hungry engine. I noticed some of the guys at some of the contest I went to were using Bru-Line air filters to give the engine a choking effect which would require you to lean it out for more power thus increasing your fuel economy. I did though however recently try the Thunder Tigre 11x4.5 on the Fp.40 which really gave good results as well  but I didn't make it into the overhead 8 before the engine started showing signs of coughing. One thing I never took into account was that a slightly larger fuel tank would've been ideal as I didn't need the entire capacity. I could've increased my tank compartment a 1/2" to give me that little bit necessary. Its a learning experience on a daily basis. I would say Paul, if you have the room optimize it. You can always pull out a 1/2 oz. or so to get you where you need to be. Ken