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Building Tips and technical articles. => 1/2 A building. => Topic started by: minnesotamodeler on October 24, 2007, 04:31:11 PM

Title: Late flying session--fuel problems?
Post by: minnesotamodeler on October 24, 2007, 04:31:11 PM

I just got back from another serendipitous (sp?) day of flying weather here in the frozen North.  Sunshine, high 50s temp, light breezes.  Great.

Took out my SkyWriter, the newly-designed Rumbler, and the Hexdrone thing I got from Frank.

SkyWriter continues to impress--I may not ever try it with an .061 since it flies so well with the .049. 

Rumbler, fast and quick-turning, best I could tell on the truncated flights (more on that in a minute).

Hexdrone--Frank, you should have tried to stunt this thing...what a ride!  It is fast, I'm thinking of pulling the .061 off and putting on an .049--at least the tank would be big enough.  Pretty squirrelly manuevering, kinda like the old Half-Fast or Wow flying wings combat planes. Not particularly stable, very touchy and jumpy and "twitchy".  Kinda fun though.  It might be tamer at a slower speed. I have better places for the .061 than on this.

The truncated flights:  None of my engines needled well or consistently today.  I'm not sure I ever ran a tank out...either starved out lean or flooded out rich.  And the difference many times was just a click or two.  I'm used to tinkering with 1/2As, but these needled very hypercritical even for me.  I even changed to different kind of tanks on two of them. No help. 

I'm thinking it's time to buy some fresh fuel...what I have is maybe 2 years old, only about 2" left in the bottom of the jug.  It was only 15% to start with, maybe it's dropped below some critical level for these little engines? 

Anyhow, I'm planning to try some filters in all the lines next time out. 

Any suggestions accepted and considered.

--Ray

Title: Re: Late flying session--fuel problems?
Post by: John Crocker on October 25, 2007, 05:09:25 AM

Hey Ray,

I've been running PowerMaster 20/20 and loving it.

Title: Re: Late flying session--fuel problems?
Post by: Paul Smith on October 25, 2007, 07:21:17 AM

I've never had a problem with old fuel in a can or jug, and I've stored it for ten years or more.

I would guess the that the issue might be old fuel in the engine or fuel tank.  When it dries up and gets funky, bad things happen.

Another issue might be cold weather performance of otherwise good fuel.  On the few occassions where I've felt the need to test something in the cold, the fuel has not been good to me.

Title: Re: Late flying session--fuel problems?
Post by: john e. holliday on October 25, 2007, 08:28:08 AM

I would suggest trying some fresh fuel first.  Then if that don't work try a little more nitro.  With the bigger engines I usually go to a hotter plug in cold weather.  Of course cold weather to me is anything in the 30's or lower.  By the way don't throw away the old fuel as you can mix it with the fresh fuel in small quantities so you don't have to throw it away.  Have fun,  DOC Holliday

Title: Re: Late flying session--fuel problems?
Post by: Andrew Hathaway on October 25, 2007, 10:45:21 AM

If you suspect your fuel is questionable, don't hesitate to try fresh fuel.  If the new fuel solves the problem don't contaminate it with the old fuel just to save a penny. 

Title: Re: Late flying session--fuel problems?
Post by: Mike Spiess on October 25, 2007, 11:38:51 AM

Sounds like water in your fuel. Remember this has been one of the most humid summers on record here in Minn.Ever time you opened the jug up you added more moisture. I happened to me this year about a week ago I had the same problem. New fuel and every thing is great. H^^

Title: Re: Late flying session--fuel problems?
Post by: Mike Spiess on October 25, 2007, 11:41:03 AM

BTW Ray I'm fireing up the .010 in a little while VD~ %^@ ~^ HB~>

Title: Re: Late flying session--fuel problems?
Post by: minnesotamodeler on October 25, 2007, 03:41:57 PM

Hey Mike,

So the issue isn't age so much as contamination...water, huh?  The fuel jug (plastic) does sit in my basement except when it goes out to the flying field. And that is a pretty moist environment, even with a dehumidifier running full time. I try not to open the jug (I have pickup lines plumbed through the lid, always plugged) but seems like I've also heard moisture can go through the plastic jug...

Soooooo anyhow, I'll try some fresh fuel. Thanks for all replies.

I'll bet that .010 sounds like a deranged mosquito.

--Ray

Title: Re: Late flying session--fuel problems?
Post by: don Burke on October 25, 2007, 04:37:55 PM

Plastic bottles are porous to things like other chemicals and moisture, fuel stored in them will eventually evaporate and also absorb water from the atmosphere through even a sealed container.  Get some metal cans.

Title: Re: Late flying session--fuel problems?
Post by: Clancy Arnold on October 26, 2007, 07:13:39 AM

Ray
I have found that the Cox .010 TD's are strange engines.  Think of running it rich for break-in at 24,000 RPM!!!

Clancy

Title: Re: Late flying session--fuel problems?
Post by: Alan Hahn on October 29, 2007, 06:58:32 AM

Before you completely give up on the fuel, consider that the cooler weather brings denser air---more O₂ to burn. Just like adding nitro. Not bad, but in this case you may be effectively over-compressed. With high nitro fuels I typically will add a head shim. Just a thought.

Title: Re: Late flying session--fuel problems?
Post by: minnesotamodeler on October 29, 2007, 04:14:15 PM

A good thought...it was a cool day, temp in the 50s, best I could hope for this late in the year. Something to try, anyhow. Thanks.

--Ray