RCU Forums

RCU Forums (http://www.rcuniverse.com/forum/)
-   Gas Engines (http://www.rcuniverse.com/forum/gas-engines-142/)
-   -   DLE 30 dies when upright (http://www.rcuniverse.com/forum/gas-engines-142/10776563-dle-30-dies-when-upright.html)

DaveE61 10-21-2011 02:35 PM

DLE 30 dies when upright
 
<p class="MsoNormal" style="margin: 0in 0in 0pt"><font size="3" face="Times New Roman">I have a new <u>rear carb</u> DLE 30 with about &frac12; gal thru it.<span style="mso-spacerun: yes"> </span>It dies every time I fly inverted for more than a few seconds. Actually the engine is upright during this period of time. I have done the following to the engine:</font></p><ul type="disc" style="margin-top: 0in"> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">I fly at 5,000 ft so I have adjusted the needles.<span style="mso-spacerun: yes"> </span>High speed is maxed and then backed off about 200 rpm.<span style="mso-spacerun: yes"> </span>Low needle is adjusted so I don&rsquo;t get a midrange burble, but might be a bit rich</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">I have soldered a piece of copper tubing to the hole on the diaphragm cover and routed it to a pill bottle in the fuselage with a small hole in it.</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Took apart the tank, made sure the clunk was free to move from top to bottom.</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">The plumbing from the tank to the carb is about 3&rdquo; of tubing with a tee in it for filling the tank.</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Vent goes across the top of the tank to the back and then forward and out the bottom of the plane</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Idles very well</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Transitions very well</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Lawn Boy at 32/1</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Will run forever if I stay upright most of the time.</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">Sags during the inverted portion of slow rolls</font> <li class="MsoNormal" style="margin: 0in 0in 0pt; mso-list: l0 level1 lfo1; tab-stops: list .5in"><font size="3" face="Times New Roman">At 1/ 2 to 2/3 throttle with the airplane inverted, engine upright, it runs for a max of 5 seconds and quits.<span style="mso-spacerun: yes"> </span>I have not tried inverted flight at full throttle.</font>[/list]<p class="MsoNormal" style="margin: 0in 0in 0pt"><o:p><font size="3" face="Times New Roman"></font></o:p></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><font size="3" face="Times New Roman">The engine just slows down and quits so I don&rsquo;t think it is going lean as that usually speeds up before it quits.</font></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><font size="3"><font face="Times New Roman">I fly off a very small strip so engine outs are always nail biters and I prefer to not experiment a whole bunch.<span style="mso-spacerun: yes"> </span></font></font></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><o:p><font size="3" face="Times New Roman"></font></o:p></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><font size="3" face="Times New Roman">Sorry for the long post, but I really need some help with this one.</font></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><o:p><font size="3" face="Times New Roman"></font></o:p></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><font size="3" face="Times New Roman">Thanks,</font></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><o:p><font size="3" face="Times New Roman"></font></o:p></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><font size="3" face="Times New Roman">Dave</font></p>

</p>

w8ye 10-21-2011 03:56 PM

RE: DLE 30 dies when upright
 
Try richening it up some and see what happens?

karolh 10-21-2011 04:30 PM

RE: DLE 30 dies when upright
 
If you are using the stock DLE plug which is known to cause running problems, replace it with an NGK CM-6 plug and quite possibly your problem will vanish. I would also suggest that you cease using Lawn Boy oil as it will carbon up your engine pretty quick especially if run rich, and instead use one of the better suited oils such as Stihl Ultra, Pennzoil, Red Line, Bel Ray or Mobil 1 to name a few, mixed at the same 32:1 ratio.

Karol

All Day Dan 10-21-2011 05:06 PM

RE: DLE 30 dies when upright
 
Dave, this may sound ridiculous but I had loose parts in a muffler giving the very same symptoms. Dan.

Truckracer 10-21-2011 05:24 PM

RE: DLE 30 dies when upright
 
DaveE61, what kind of plane is it in? cowled, uncowled? Etc. Stock muffler or other?

AirWizard 10-21-2011 06:33 PM

RE: DLE 30 dies when upright
 
I have the same problem with a DA 85 using penzoil 40 to 1 on a extra 330

Tired Old Man 10-21-2011 07:08 PM

RE: DLE 30 dies when upright
 
Lean the top end ending the 200 RPM rich thingie, replace the plug with NGK, ditch the diaphragm tube, verify the bottom tuning is on target, dump the Lawnboy. The engine is probably drowning.

jedijody 10-21-2011 07:26 PM

RE: DLE 30 dies when upright
 
As stated above your description of mixture adjustments would leave your engine drowning rich. Fully warm up the engine, adjust the high needle for peak RPM and no richer, lean the low needle out untilit looses the ability to transition from idle to full throttle, then richen just enough until transition returns, follow the rest of the above advice, except richening the mixture adjustments.

Even though it sounds as though you feel confident in your fuel system and plumbing I would urge you to revisit it. The description of the engine slowing down then speeding up just before dying is aclassic symptom ofrunning out of fuel. Make sure your clunk isn't hanging up on the bottom of the tank, make sure your clunk line is not sucking air on the inside of the tank.

If the engine dies and after landing the fuel line is full of air you knowthe carb issucking nothing but air.

MetallicaJunkie 10-21-2011 07:28 PM

RE: DLE 30 dies when upright
 
get rid of the pill bottle and let the tube breathe inside the fuse..... i had 3 dead-sticks in a row when i did the same thing a few years ago, except i did mine in a sealed balsa box (1.5" balsa cube)

TheRickster 10-21-2011 07:59 PM

RE: DLE 30 dies when upright
 
Get a friend to hold the plane inverted and suck out the fuel observing the fuel line for bubbles or inconsistant flow. If that checks out then the issue has to be either diaphragm venting or needle settings.. Also check all your ignition wiring to be sure thhere is no wires flopping about that might be giving you intermittant ignition voltage..

Rick

Tired Old Man 10-21-2011 08:19 PM

RE: DLE 30 dies when upright
 
After all that all they need to do is swallow[X(]:eek:

TimBle 10-21-2011 10:57 PM

RE: DLE 30 dies when upright
 
why do people solder vent tubes over the breather hole in the carb body?

Super08 10-22-2011 12:26 AM

RE: DLE 30 dies when upright
 
In some cowled planes it is needed to route a tube to a place where the air pressure is stable. Some cowls have problems with pressure building inside the cowl in some or all flight attitudes. Usually better ventilation of the cowl solves the problem though.

TimBle 10-22-2011 12:54 AM

RE: DLE 30 dies when upright
 
yeah but the act of soldering could result in a blocked vent. Thats not good.

Super08 10-22-2011 01:16 AM

RE: DLE 30 dies when upright
 
1 Attachment(s)
LOL if a person solders that bad I don't think they should be soldering anything. It is pretty simple to do. Anyway the ones I have done I solder the hole and plug it on purpose. Then I drill and tap a new hole in the center of the cover and use a brass nipple with red loctite.

a1pcfixer 10-22-2011 02:35 AM

RE: DLE 30 dies when upright
 

Quote:

ORIGINAL: TimBle

why do people solder vent tubes over the breather hole in the carb body?
To stabilize the atmospheric pressure variations on that diaphragm;
http://www.prme.nl/forum/viewtopic.php?t=205

a1pcfixer 10-22-2011 02:38 AM

RE: DLE 30 dies when upright
 

Quote:

ORIGINAL: jedijody

....................Adjust the high needle for peak RPM and no richer, lean the low needle out until it looses the ability to transition from idle to full throttle, then richen just enough until transition returns...............................
You forgot step #1;

Get the engine completely/fully warmed up first,
then do your tuning!

3136 10-22-2011 03:42 AM

RE: DLE 30 dies when upright
 


I had a similar problem once, I stuffed around with the mix screws, so did everyone at my club.
I was changing the engine, and prepared to throw it out when I found a plumbing problem.
That engine runs reliably now.
As Jodi said, look at the fuel line after it cuts out, if it's empty that's where to look.
Have you got tight connections on every joint?
Any chance of air being sucked in?

Also did you run the engine in the plane before you added the line to diaphram cover?</p>

garyr1 10-22-2011 04:44 AM

RE: DLE 30 dies when upright
 
Just do as JeoJody says and you'll be fine.
He's THE MAN: did a ton of development on this engine with the mfgrs, etc.
My DLE30 v2 gave me a few deadsticks too while breaking in and getting settings right.
NGK plug is a MUST. The stock DLE plug has crappy ceramics and might come apart internally causing damage, so just round-file it. Stihl oil is great.
Your breather line to the fuse is good. I had to do it on mine too because of rich flameouts on inverted and outside manoeuvers...sort of sounds like your situation.
After 2 or 3 gallons through mine, I have a super running engine....very strong! Using Xoar 19 x8 for IMAC stuff. 18x10 is faster if you do Warbirds.
Oh, and it's in a Sbach...cowled inverted setup. Pretty typical.

TimBle 10-22-2011 07:07 AM

RE: DLE 30 dies when upright
 

Quote:

ORIGINAL: a1pcfixer


Quote:

ORIGINAL: TimBle

why do people solder vent tubes over the breather hole in the carb body?
To stabilize the atmospheric pressure variations on that diaphragm;
http://www.prme.nl/forum/viewtopic.php?t=205

So there's the possibility of a local high pressure or low pressure around the carb....
Strange that the people who designed the carb never thought of this

Super08 10-22-2011 07:15 AM

RE: DLE 30 dies when upright
 
The carbs were designed for trimmers and chainsaws not airplanes and were adopted by the model airplane industry.

Super08 10-22-2011 07:16 AM

RE: DLE 30 dies when upright
 
..

jedijody 10-22-2011 07:52 AM

RE: DLE 30 dies when upright
 

Quote:

ORIGINAL: TimBle

yeah but the act of soldering could result in a blocked vent. Thats not good.
You must be joking, right?

Tired Old Man 10-22-2011 07:58 AM

RE: DLE 30 dies when upright
 
Doug,

It gets even better. Most of the engines being sold for RC were never designed, at least in the original design before hijacking, to use a two needle carb. The original concept had them equipped with a single needle carb intended to meter fuel effectively at two speeds. High idle and wide open throttle. That intention was cast aside when the engines were converted to a model airplane function. Most of the small engines are running far richer than the original designed use intended for them.

On to the vent tube thing. Because SOME planes require a balancing act to be performed does not in any way imply all planes need it. In truth only a very few planes experience the pressure imbalance. Unfortunately a lot of people have a tendency perform "just in case" work and fiddle with their diaphragm covers. In doing so they quite often alter the self compensating functionality of the diaphragm and create exactly the problem they were trying to prevent. A vent tube can cause as many, or more, problems than it was intended to cure.

As I mentioned in another thread, the cause of a great many engine issues is people trying to fix something that wasn't broken. Unfortunately most of those involved in that activity are not cognizant, or qualified to do what they are doing and don't have the knowledge necessary to reason through their actions. But somewhere, someplace, they read how one person did such and such, or was told by some lifetime glow flyer at a field that such and such would cure ailments they didn't know they did or didn't have. There's at least two examples of that in this thread alone.

Of all the planes I've owned and worked with, I've only come across two that needed a vent tube. All the others would have run MUCH worse with one. If people understood anything at all about their carbs, they would know that stabilizing the air pressure at the diaphragm defeats the intended design function of altitude compensation. One other thing, if they have a rear carb engine it would be damned difficult for it to be experiencing any kind of pressure imbalance issues unless they had added a vent tube. That is called shootng yourself in the foot. Duh!

av8tor1977 10-22-2011 09:29 AM

RE: DLE 30 dies when upright
 
I don't understand how running a static tube from the vent hole to an area of static air in the fuselage would cause a problem? (Given of course, that the fuselage isn't pressurizing....)

AV8TOR


All times are GMT -8. The time now is 02:07 AM.