DLE-30 Dies When Inverted

[3dcarter]

I think it's just a problem with the DLE 30's in general. Most every 30 in our local club has had issues. When I had mine, it ran much, much leaner when the plane was inverted as well. I sold the plane, and the succeeding owner put on a new carb, as well as a DLE-55 ignition. The new ignition helps out a crazy lot.

 

[AtomicFlyer]

I think it's just a problem with the DLE 30's in general. Most every 30 in our local club has had issues. When I had mine, it ran much, much leaner when the plane was inverted as well. I sold the plane, and the succeeding owner put on a new carb, as well as a DLE-55 ignition. The new ignition helps out a crazy lot.

It does seem as though there isn't a common solution to this issue. Which leads me to suspect that the manufacturing tolerances on these engines is not great. I'm not generally opposed to replacing parts until I find something that fixes the problem. But also, like most people, my hobby budget isn't unlimited. So I'm hoping that Troy-Built Models where I bought the engine a couple months ago will be able to help me out under warranty.

So far here is a list of recommendations from the forums and my club-mates
-replace the tank
-replace the clunk
-change from 3 line to 2 line tank
-run richer
-run leaner
-replace the carb
-install the carb equalization mod
-use a manometer to measure carb pressure
-mount the tank upside down
-replace the ignition
-add weight to the clunk
-clean the carb
-replace the carb with a "real" Walbro

and my favorite of all.....DON'T FLY INVERTED!

I appreciate any and all suggestions. I'm going to get this fixed or trash my plane trying!

Marc

 

[gyro]

Good luck Marc, hope you get it fixed soon, this engine is beast when running correctly, and the Edge is such a fun plane you deserve to enjoy it!

 

[AtomicFlyer]

At the field yesterday my club mates brought up an interesting point that I don't fully understand. When I fly inverted the vent line is covered with fuel and therefore not venting. So the carb will pump fuel but a vacuum will build up in the tank. Is the answer to this just that the pump will overcome the vacuum in the tank?

One guy said that he always mounts his vent line on a piece of brass tubing facing forward so the vent is pressurized during flight.

Marc

 

[gyro]

At the field yesterday my club mates brought up an interesting point that I don't fully understand. When I fly inverted the vent line is covered with fuel and therefore not venting. So the carb will pump fuel but a vacuum will build up in the tank. Is the answer to this just that the pump will overcome the vacuum in the tank?

One guy said that he always mounts his vent line on a piece of brass tubing facing forward so the vent is pressurized during flight.

Marc

Interesting thought... Could it also be that the pump in the carb isn't functioning properly, and thus unable to pump when the vent line is covered?

Maybe you could try a carb rebuild kit and see if that helps. The stock rubber in the DLE carbs may be too stiff?

I dunno, I'm just brain storming here...

 

[AtomicFlyer]

Interesting thought... Could it also be that the pump in the carb isn't functioning properly, and thus unable to pump when the vent line is covered?

Maybe you could try a carb rebuild kit and see if that helps. The stock rubber in the DLE carbs may be too stiff?

I dunno, I'm just brain storming here...

I appreciate any and all brain storming! On the last flight of the day yesterday I inverted the tank in the plane at the suggestion of a club mate. So in that configuration the vent line would be plugged with fuel when the plane was upright. Yet the motor ran fine upright. And then I went inverted and the motor ran for more than a minute (another club member was actually timing for me). After about a minute of inverted figure 8s I went full throttle and pushed elevator to do a half outside loop to upright. The engine died near the top of the loop. That may have been the most inverted flight I ever got but I'm not really sure what it told me since the motor also ran upright.

I was going to try that again with a full tank but when I went to pump fuel into the tank it all came out the vent (duh!) which was now under fuel. I decided to stop there and quit while I still had a plane in one piece.

So far, the ideas I like the best are rebuilding the fuel tank as a two line tank (the fill clunk won't tangle up with the pickup clunk) and rebuilding or replacing the carb.

Marc

 

[gyro]

I appreciate any and all brain storming! On the last flight of the day yesterday I inverted the tank in the plane at the suggestion of a club mate. So in that configuration the vent line would be plugged with fuel when the plane was upright. Yet the motor ran fine upright. And then I went inverted and the motor ran for more than a minute (another club member was actually timing for me). After about a minute of inverted figure 8s I went full throttle and pushed elevator to do a half outside loop to upright. The engine died near the top of the loop. That may have been the most inverted flight I ever got but I'm not really sure what it told me since the motor also ran upright.

I was going to try that again with a full tank but when I went to pump fuel into the tank it all came out the vent (duh!) which was now under fuel. I decided to stop there and quit while I still had a plane in one piece.

So far, the ideas I like the best are rebuilding the fuel tank as a two line tank (the fill clunk won't tangle up with the pickup clunk) and rebuilding or replacing the carb.

Marc

Marc,
I've got a old fourtitude 16oz tank I'm not using, I'll send it to you just to see you stop messing with that tank you have in there now.

It's the same tank that was in the 71 Slick that I used to break in my DLE 30...

 

[AtomicFlyer]

Marc,
I've got a old fourtitude 16oz tank I'm not using, I'll send it to you just to see you stop messing with that tank you have in there now.

It's the same tank that was in the 71 Slick that I used to break in my DLE 30...

Thanks for the offer Gary. I may take you up on it. But I'm going to wait to hear what Troy-Built has to say first. I'm hoping my pain and suffering is at least building some character. Besides, cutting brass tubing and soldering on barbs is cathartic.

Marc

 

[3dcarter]

do you have a loop in your vent line? that might help. I know if you run your vent line straight out of the tank, it might fill with fuel, so you have to run a loop on top of the tank. that might help a little!

 

[AtomicFlyer]

do you have a loop in your vent line? that might help. I know if you run your vent line straight out of the tank, it might fill with fuel, so you have to run a loop on top of the tank. that might help a little!

Thanks for the suggestion Carter. The photo below shows part of the vent line. Is this what you're talking about? The vent line comes out of the tank, then goes towards the back of the tank and loops back up front. Then I run it out the bottom of the fuselage. You may notice that I have a filter in the vent line. I put that in when I first built the plane at the suggestion of someone who said it would prevent crap being pulled back into the tank. But I removed the filter element yesterday as a test and it still died when I rolled inverted.

But that also brings up the question I had before...When I fly inverted, the vent line is under liquid gasoline. So what prevents the tank from going under a vacuum and starving the engine? Is it that the engine pump is strong enough to overcome liquid gas in the vent line?

Marc