DLE-30 Dies When Inverted

[AtomicFlyer]

I called Troy-Built models today and talked to their engine guy Jeff. He's a friendly guy and was willing to chat about my issue.

I explained my issue with the engine dying when inverted and told him what I tried. Here's what we chatted about:

-I can send the motor back under warranty for a free checkup, but they'll just run it upright and inverted on the bench.
-I explained that I ran it inverted on the ground and it ran fine. And I inverted the tank and flew the plane upright and it flew fine. So he thinks the fuel delivery is fine.
-He said the carb doesn't care if it's upside down and many people run it that way because they rotate the carb 180 degrees for ease of linkage hookup. So he thinks the carb is fine (the engine starts easy and has fine and quick transition to full throttle).

Jeff thinks the problem is with airflow (or lack thereof) into the carburetor. His suggestion is to take off the cowl, add weight as needed for CG, and fly inverted.

So I'm going to take off the cowl and fly inverted next weekend!

Three other things I got thinking about tonight that may or may not be an issue:
-I had the "silencer" installed wrong. I doubt it makes much difference, but _maybe_ the silicone tubing was bending over and cutting off the exhaust? So I installed the silencer correctly by pressing the aluminum silencer directly into the exhaust instead of on the end of the silicone.
-I have all the exhaust holes on the bottom of the plane cut out. I'm thinking _maybe_ I have so much cutout there that I'm creating a vacuum when inverted which is starving the carb?
-There is no hole cut in the firewall for the carburetor. The carburetor is only about 1/2" from the firewall.

I'll report back once I get a chance to fly. I'm a working stiff so I only get to fly on the weekend.

Marc


Silencer installed WRONG at end of silicone tubing.


Silencer installed correctly in exhaust with silicone tubing to hold it in place.


Vent holes opened up in bottom of plane.


Clearance between carb and firewall.

 

[gyro]

Definitely agree with opening the firewall to improve airflow into the back of the carb.

Also, unless you desperately need the silencer, take it off and see it it helps. DLE didn't design it into the muffler, so you should try and get it running without all the extra stuff.

 

[AtomicFlyer]

Definitely agree with opening the firewall to improve airflow into the back of the carb.

Also, unless you desperately need the silencer, take it off and see it it helps. DLE didn't design it into the muffler, so you should try and get it running without all the extra stuff.

Good suggestions, both. I'll try them and post back the results.

Marc

 

[SnowDog]

good luck! keep us posted.

I agree a little space behind that carb might be good.

 

[AtomicFlyer]

good luck! keep us posted.

I agree a little space behind that carb might be good.

I've got my coping saw warmed up and ready to make a hole in the firewall. My flying field is about 5800' ASL so that may have something to do with my setup needing to be a bit different.

Last weekend, when I wasn't going inverted way up high and waiting for it to die, I was doing some low upright harriers straight down the runway. That was a pretty cool feeling with a plane that big (big for me anyway) and got me really wanting to get this inverted problem solved. I'm sure I'll be obnoxiously excited when I get it solved and you'll all know.

Marc

 

[AtomicFlyer]

It's been cold and windy all day and more of the same forecast for tomorrow (and next weekend). And since I can't do much about tuning until I get to the field I decided to make some progress on the other working theory which is that I'm starving the engine for air.

So, IF the engine is starving for air, I'm thinking it's caused by one of three things:
1) Cowl cutout not big enough
2) Cooling exit holes too big (creating a vacuum when inverted???)
3) Carb air intake too close to solid firewall.

The modifications I made were:
1) Cut open more of the cowl.
2) Covered up some of the exit cooling holes in the fuselage.
3) Cut a hole in the firewall behind the carb.

I also pulled the spark plug (which looked OK to me) and opened up the gap a bit based on stuff I read online. I opened it from 0.017" to 0.024" Can any of you experts tell me if my plug looks about right after 3/4 gallon of gas has been run through it?

The engine actually seems easy to tune and not that sensitive so it seems like once I find the cause of the engine dying while inverted it's going to be pretty reliable.

Marc

I opened the cowl a bit more


I covered up some of the exit cooling holes


I cut a hole in the firewall behind the carb


The engine mounted with the hole cut behind the carb


This is the plug after 3/4 gallon of gas run with it


I opened the gap from 0.017" to 0.024"

 

[gyro]

Marc, great job on all your mods. For gaping these plugs, I just use an xacto #11 blade width.

For the plug, I'd let some experts chime in, but it looks a little gunked on the top, but not elsewhere... Haven't seen one that way before.

 

[AtomicFlyer]

Marc, great job on all your mods. For gaping these plugs, I just use an xacto #11 blade width.

For the plug, I'd let some experts chime in, but it looks a little gunked on the top, but not elsewhere... Haven't seen one that way before.

Thanks Gary. I was running it kind of sloppy rich on the last few flights because someone suggested that might solve my problem with it dying inverted. It was also leaving a trail of oil on the underside of my fuselage. But this is the first time I've pulled the plug since the first flight.

Neat idea about the #11 blade. My digital caliper only reads to hundreds, but it did read 0.02 on the #11 blade.

Marc

 

[keith.ille1]

https://www.youtube.com/watch?v=T6fIsd-ZI5U&feature=youtube_gdata_player
I hope you have more luck then I did! 3 carbs,3 gas tanks,2 ignition s, bowman ring and Reed mod and not to mention 4 different dle 30 s because warranty always just sent me a new motor cause they couldn't figure it out either!

 

[AtomicFlyer]

https://www.youtube.com/watch?v=T6fIsd-ZI5U&feature=youtube_gdata_player
I hope you have more luck then I did! 3 carbs,3 gas tanks,2 ignition s, bowman ring and Reed mod and not to mention 4 different dle 30 s because warranty always just sent me a new motor cause they couldn't figure it out either!

I saw your video when I was doing research into my issue. Sorry you weren't able to get it resolved. I congratulate you on your perseverance.

Your issue is a bit different from mine. I'm able to roll the plane over while on the ground and the engine runs fine. My issue only comes up when I'm in the air.

After I did the mods as detailed in post #26 above I ran about half a tank through the engine while in my driveway. It ran well, just like it always has in my driveway. The weather looks to be decent on Sunday so I'm hoping to get it in the air and go inverted.

The only remaining mod I have planned is to replace my three line tank with a two line tank in case my supply clunk is getting tangled up with my fill/drain clunk. One of the older guys in my club has a lot invested in this theory, though I'm convinced the tank is fine (after rebuilding it for the fourth time). If that doesn't work, I'll probably sell off this engine to another guy in my club who already made me an offer and I'll start looking at another power plant other than the DLE-30. I'd really rather fly than mod. But I ain't giving up on it just yet!

Marc