what happened
 

Ok here is my problem. I am coming into my approach and as I punch my throttle to get out of my approach it dead sticks. Why is it doing this? My engine is a OS LA 40 if that helps

Thank you

RE: what happened
 

Low end mixture may be too lean.

RE: what happened
 

Mixture could be wrong. Idle speed could simply be too slow, raising it just a 100 RPM or so would help even if it means using a finer pitched prop to keep the speed down in final.

RE: what happened
 

how can i fix my mixture. and i am uesing a 11by5 so would a 10by6 work

RE: what happened
 

Adjust your low end with the pinch test.

That carb is an airbleed carb but the pinch test works for them as good as for lowspeed needle carbs.

The pinch test is described all over these forums. But it's basically simple.

Let the engine settle into the idle.
Pinch the fuel delivery line closed and listen.
If the engine speeds up just before dying, the low end is too rich.
If it just dies, it's too lean on the low end.

With an airbleed carb the way you adjust the low end is by means of a screw that closes off the airbleed hole.
You turn the screw in to close off the hole and that richens the low end.
You turn the screw out to open the hole and the increased air leans the low end.

Only adjust each time by 1/8 turn.

If the engine is only just now breaking in, it's a new engine, it's normal that the lowend won't be perfectly adjusted.

RE: what happened
 

couldn't hurt to check your glow plug also

RE: what happened
 

What's your airplane?
What prop was on it?

How much time on the engine?

How much time on the glowplug?

RE: what happened
 

On a LA40 a 10x6 would be more appropriate IMO. In addition to da Rock said in post #5, you should be able to idle the engine for 30 seconds and then move it immediately to WOT and have it accelerate without stumbling or quitting.

As he said, if a new or newer engine, you can expect to need to retune it following complete break-in. After break-in the idle screw can be virtually forgotten unless you accidentally move it or experience MAJOR atmospheric changes like moving into the mountains.

RE: what happened
 

once you get the engine properly tuned be careful being low and slow and "punching" the throttle....you just might wind up inverted on the side of the runway...

RE: what happened
 

And the airplane could be hurt worse than you are. ;)

RE: what happened
 

Well airplane is an avistar
Prop is 11by5
The engine is fairly old it trained someone before me so I don’t know exactly how old it is
I’m thinking about putting a new plug on because the other is probably what went with the engine at first

And well as I probably did punch the throttle I will stop next flight

Da rock I didn’t understand post 5 so if you can reword it so a beginner without a lot of engine experience it will help

RE: what happened
 

Let us know which terms you don't understand and we'll explain them. You're going to need to learn them someday, and we can help.

RE: what happened
 

Whole thread on the pinch test, with some good advice PLUS a bit of "Who's on first":

http://www.rcuniverse.com/forum/m_59...tm.htm#5923875

RE: what happened
 

some terms are
low end
airbleed carb
lowspeed needle carbs
airbleed hole
increased air leans

RE: what happened
 

When an engine operates at full throttle, that's it's top end.
When it's idling, it's operating at the low end. It's idle performance is it's low end performance.

There are two carburetor designs we see most in our glowfuel model engines. These two designs are basically different ways for the carbutetors to deal with the engine's demands for wide open performance and the different demands for idle or low end performance. The amount of fuel to air mixture if the problem. The engine needs one ratio of fuel/air for top end and a different ratio for low end. The most popular design right now is a carb that controls the intake mixture by using an additional needle valve to change the ratio when the carb is partially closed for the low end performance. The other method deals with the ratio by regulating air into the carb through a hole for the low end performance. Those are called air-bleed carbs. They have an airbleed hole in the front of the carb.

The popular carbs that aren't airbleed.

The ratio of fuel/air can have more fuel to air or less fuel to air. When there is more fuel to air, the mixture is said to be rich. When there is less fuel to air, it's said to be lean.
With an airbleed carb, increasing the size of the airbleed hole lets increased amounts of air into the area where the fuel and air mix, and the mix has more air than it would otherwise, so the mixture is leaned.

RE: what happened
 

But Bruce has given you two very good bits of advice.

The idle speed could simply be too low. Will it sit at idle for 30 seconds? It should. Does the idle taxi the airplane? It shouldn't. But it can be increased until it will and then backed off a click or two and the reliability in flight should improve.

And the engine should go to WOT from an extended idle without skipping a beat. If it won't, THAT's when the lowspeed should be tuned. (We say "the lowspeed should be tuned" when we don't know if your engine has a needle or airbleed for that tuning. If somebody told you to adjust your lowspeed needle, what'd you do? You ain't got one.)

RE: what happened
 

10 / 6 prop for LA 40 might work better. A good starting point for the air bleed opening is open more than 3/4 open. put a "T" pin in the hole and GENTLY close it on the pin. Remove pin and run it. It should be close enough to start your pinch testing. This works pretty well and so does visually starting at 50% closed ( or open depending on your mood;);)).

RE: what happened
 

Ok so while I’m at my field I should tune it do a pinch test and try replicating what happened before and see if it happens again

RE: what happened
 

First, let it warm up.
Then run it up to WOT (wide open throttle) and set the highspeed needle.
You do that by opening it until the engine is obviously rich. Smoking exhaust and slower rpm sound.
Then bring it to idle and let it go. It should hold fairly steady for you to get bored and wonder how long you should be standing around wondering how long you should be standing around. ;)
If it won't do that, THEN do a pinch test at idle.
If it did idle happily until you ran out of patience (ok, not that long)......
Slam the throttle wide open from that happy idle and see if it accelerates or chokes and dies.
If it stumbles or anything other than cleanly accelerating, THEN do a pinch test at idle.

Sorta like you said, but allowing for what might happen.

RE: what happened
 

Want a good way to set the wide open throttle?

With it running WOT, open the highspeed needle until the rpms obviously start to slow. You've just richened the high speed mixture. And the important thing is that you know for sure that the needle setting is more than rich enough. You've starting from a safe setting.

Now start to turn the highspeed needle in slowly. This leans the mixture. And the engine will start to pick up speed. Keep turning in until the engine is screaming. Keep turning until it finally starts to slow down. Instantly back the needle back out about 3-4 clicks. It was running a safe ratio of fuel/air until it started to slow down. Then it was running too lean. That's when there isn't enough fuel in the fuel/air mix and the fuel is what lubricates the engine. Too lean, and not enough oil, and the engine heat and friction wears the sucker out in one flight. So when you finally get to the slowdown indicating a too lean mixture, you quickly turn the needle back to get a safe mixture. And that's usually 3-4 clicks back.

Then pull the TX throttle back to idle and start counting sheep.