Stormlord wrote:
> I have a fairly new (less than a year old) OS .61FX mounted upright in a
> Twist 3D 60 with a 13x6 prop. The engine has been properly broke in and
> has about 20 flights on it.
> I'm having a problem that I'm not sure how to solve.
> When flying the plane at around 1/4 throttle, if I fly inverted, it
> will die and I have to dead-stick the plane to the ground.
> It doesn't seem to happen when I do this at 3/4 or higher throttle, but
> it does stutter from time to time, it just doesn't quit.
> I never have a problem whatsoever if I don't fly inverted ... runs
> through a tank of fuel just fine and I can do anything I want with the
> plane.
>
> At first, I thought the clunk was getting stuck and sucking air, but
> this is not the case.
> The clunk is free and not getting hung up anywhere ... also, when the
> plane lands dead-stick, upon inspection, there is fuel in the fuel line
> all the way to the carb with no air bubbles in it.
>
> Is there a way to correct this problem? Anyone ever had this happen
> before? I'm not sure where to start, I've never had this issue
> previously.
>
> I've tried leaning and richening the engine with the main needle valve
> (no difference - the problem is repeatable), and I've changed to a
> hotter glow plug (from an OS 8 to a 3) so far.
>
> I'm just not sure what's causing the condition, so I'm not sure what to
> try to fix it.
>
> Could the engine be flooding itself upside down somehow, causing the
> glow plug to foul out? What would cause that and how can it be
> corrected?
>
> I pulled the glow plug after one of the dead-stick landings and it was
> not wet, but with a hot engine, I thought maybe it had eva****ated after
> normal level flight had resumed (even though the engine was not
> running).
>
> Just not sure where to go with this and I'm searching for some ideas to
> try ....
>
>
What Dave and Retread said, plus:
For a diagnostic, why not put the plane on a stand and run it inverted
on the ground, at the deadly throttle setting? Then you can see what's
going on close up, you can see if you can adjust the mixture to keep it
going, you can maybe pinch the fuel tubing to see if it's too rich or
lean (if it's too rich pinching the line will make it speed up, too lean
it'll sag or die immediately instead of after a bit).
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
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