How much fuel are you using?

[Paul Taylor]

I have this one LA 46 that is using less the 3.5oz for a pattern.

And I know the electric guys answer will say 0.

[Will Davis]

4.25 ounces sig 10 %  nitro, 20% oil, 1/2 syn, 289 Venturi, stock muffler 12 4 apc. To increase mileage you can use  a smaller Venturi,less nitro, less oil , restricted muffler,or a smaller , low pitch prop

[Tim Wescott]

I'm using somewhere between 3.5 and 4 ounces on an LA 46.

This in a 50 ounce Fancherized Twister, with four layers of pantyhose over a .275 inch venturi -- with a bigger plane, I'd probably run less nylon net, and use more fuel.

Edit:  Fuel makes a big difference.  I had been using mostly synthetic fuel, and using much less of it.  I'm using 11% castor, 11% synthetic now, and using what I say above.

[Paul Taylor]

Last flight was 2.75 and still a bunch of laps after pattern.
7/22 synthetic blend with a little aero lube.

[Tim Wescott]

Last flight was 2.75 and still a bunch of laps after pattern.
7/22 synthetic blend with a little aero lube.

7% synthetic and 22% castor?  Or 7% nitro, 22% synthetic, and no castor?

Full pattern or beginner?

What's the plane, how heavy is it, and how fast is it flying?  What prop are you using?  Do you know how big the venturi is?

If the plane is flying right, I suppose I shouldn't question the fuel usage.  But I was struggling with my LA 46 engine run just this spring, and any time that I used that little fuel for a pattern it meant that the thing was in a screaming-fast runaway.

[Robertc]

What is the altitude at where you're flying?  Mine will vary 3/4 oz from 5000 feet to sea level.

[Paul Taylor]

Not sure of the altitude. Bristol Wi.

7 nitro. 22 oil. Syn/castor blend.
Full pattern launching at 9300+
11x4 APC.

[Tim Wescott]

Wikipedia lists three Bristols in Wisconsin.  But the one in Dane county is at 909 feet.

[Randy Cuberly]

5 3/4 oz, 15% nitro, 20% half and half, PA65 on pipe, 61 oz Whitely Shoestring, Tucson AZ 2400 ft altitude, 9600 RPM launch, Three blade 12.5 X 4.5 Carbon prop, 5.4 sec laps on 68 ft lines.
Could use a larger venturi, but power is more than ample.  Love this PA65...

Randy Cuberly

[Steve Helmick]

Last flight was 2.75 and still a bunch of laps after pattern.
7/22 synthetic blend with a little aero lube.

We're not getting proper details of your combination in one post, making it difficult to get a clear picture. 

Tim asked about your fuel mix. It isn't yet clearly stated. You stated 11 x 4 APC, but on the other post about your Randy Aero .46LA, you said you were using the TT 11 x 4.5. Did you say what venturi size or spraybar size is? Any air filter on top of that?

I'd assume you want to increase your fuel burn, and think that's a really good idea, because the more you burn the more accurate your run time, the more thrust you'll get, and the happier the engine will be. You can do that by increasing the oil content, increasing the nitro content, increasing the venturi size, increasing the prop load.....or reducing backpressure.  Could this be just due to the altitude, heat and humidity at your FIL's farm in Wisc? Is it fixable, based on what you have with you, or can obtain locally? Do you have enough ground clearance to use a 12" prop, or are you limited to an 11" prop? IMO, inadequate ground clearance is a huge mistake, often seen.  Steve

[Paul Taylor]

Ok let me see it I can make it clear.

This is not a Aero LA 46

I do not know the size of the Venturi but compaired by sight it does not appear to be over or undersized to my other LA's. The fuel is 7% nitro and 22% oil.  Don't know how much is synthetic.  It has 1 oz of Aero oil added to the gallon
As stated the prop is a APC 11x4.
This engine has always did the pattern with less then 4oz of fuel. It has been on a Teosockie (someone chk the spelling) a Full size profile Force and now this Tutor.
This engine does have a Aero product NVA and metel back plate. Not sure on the plug. It has been hot here but very doubtful it has anything to do with this engine doing the pattern on less then 3oz of fuel.
Oh yea launching at 9300+. Plane weighs 48oz.
What else do you want to know?

[Randy Cuberly]

Ok let me see it I can make it clear.

This is not a Aero LA 46

I do not know the size of the Venturi but compaired by sight it does not appear to be over or undersized to my other LA's. The fuel is 7% nitro and 22% oil.  Don't know how much is synthetic.  It has 1 oz of Aero oil added to the gallon
As stated the prop is a APC 11x4.
This engine has always did the pattern with less then 4oz of fuel. It has been on a Teosockie (someone chk the spelling) a Full size profile Force and now this Tutor.
This engine does have a Aero product NVA and metel back plate. Not sure on the plug. It has been hot here but very doubtful it has anything to do with this engine doing the pattern on less then 3oz of fuel.
Oh yea launching at 9300+. Plane weighs 48oz.
What else do you want to know?

Hi Paul,
What is your line length and lap times.
Since this is a profile does the engine lean out quite a bit after launch?
Does it run in a steady four stroke or a wet two through the pattern...2-4 or what?
All of these things can drastically effect fuel usage.
You may also have a LA20 size venturi in the engine (.256 diameter).  I've seen LA46's come from the box with a wide array of venturi sizes, from .250 to .298.  Sometimes it seems they just provide whatever they have on hand at the time. 
Venturi size will have a large effect on the fuel usage, type of run, power, etc.

Cranckshaft fit in the front bearing can also have an effect on fuel usage...loose tends to lose fuel around the thrust washer...and provide better lubrication for the plain bearing. (fairly common with LA's)
Tight can present other problems like poor shaft lubrication and heating of the crankcase causing inconsistent runs (this is NOT a common problem with LA's but I have seen a couple).

An 11X4 prop is pretty small and lightly loaded for an LA46 and they typically like larger props in the 11.5 to 12.25 range.

Your LA46 in a fairly light airplane with a smallish prop is very lightly loaded and that certainly explains some of the low fuel usage.

Randy Cuberly

[Steve Helmick]

I have read that the OS LA-CL versions are modified in the USA from R/C versions. Whether they come without the throttle from Japan or not wasn't stated. I could see the CL venturii being made in the USA on an antique automatic screw machine (LM Cox had a bunch of them) in somebody's garage, possibly with a minimum wage operator. I would expect that he's not inclined to throw away any that he can get paid even $1 for. Assuming that normal tolerances would be +/- .010", and there are supposed to be .25LA and .40/.46LA sizes, it's not real surprising that they might get mixed up and have a fair amount of variation. Maybe by the vendor that made them, or maybe in the warehouse at the OS distributor. I would suggest checking the venturi bore before you run the engine, and get one that's an appropriate size from a reliable vendor, like Randy Aero or Jim Lee.  If the one your engine comes with is too small, you might be able to drill it out or have a buddy ream or bore it out. Steve

[Paul Walker]

At VSC this year I used 4.4 ounces a flight and barely got the pattern it. Used 10% vitiman N and 29% vitiman C in the fuel.

The venturi just happened to be missing the insert it came with!

Could be your venturi is too restrictive.

[Lauri Malila]

Hello.

I use 3.3...3.4oz./6.5min. flight with my .77 engine. But I'm aiming to about 2.5oz. consumption when the engine is ready.
I allways fly first a flight with full tank, and based on the lenght of that flight I remove fuel from tank to make it 6.5min. It's easy to calculate how much to remove but somehow I don't trust my math skils when in a contest, so I use a simple table. The left paragraph shows the flight time with full tank and the right one shows how much must be removed from full tank for a 6.5 min. flight. Simple and idiot-proof! L