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Author Topic: engine cuts out or stutters in last 2 maneuvers  (Read 904 times)

Offline John Craig

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engine cuts out or stutters in last 2 maneuvers
« on: October 30, 2018, 08:33:00 AM »
A nice running FP 25, stock muffler, 10-4 prop, on a profile RST, launch 10,400, wide square wedge  3.5oz tank on uniflow pressure, level flight after bailing out of the overhead 8 the engine runs fine for 7 min, leaning for only the last 3 laps, I kicked the rear of the tank out 3/16 with no change, line tension is fine.

Suggestions?

Chicken Hopper?

All help is appreciated.
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Offline RandySmith

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #1 on: October 30, 2018, 09:16:26 AM »
Quote from: John Craig on October 30, 2018, 08:33:00 AM
A nice running FP 25, stock muffler, 10-4 prop, on a profile RST, launch 10,400, wide square wedge  3.5oz tank on uniflow pressure, level flight after bailing out of the overhead 8 the engine runs fine for 7 min, leaning for only the last 3 laps, I kicked the rear of the tank out 3/16 with no change, line tension is fine.

Suggestions?

Chicken Hopper?

All help is appreciated.

Take it off of pressure, and  yes  a Chicken hopper  could also help you with that, many have good luck with plastic tanks setup uniflow on that engine Too

Randy
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Offline Dennis Toth

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #2 on: October 30, 2018, 05:53:43 PM »
John,
Do what Randy said, only thing I would add is to position the uniflow vent up away from the fuse in the free airflow. On the Ringmaster pictured I have a small brass bracket the hold a short piece of copper tubing off the back engine bolt then connect the uniflow vent line with flex silicon tubing. I have done this on a few models that had been giving erratic runs and all the issues went away with this change.

Also, 7 mins seems like at least a minute longer than needed for the PA pattern, what line length and lap time are you at? Normal for a smaller ship on 60' lines would be around 4.9 sec to 5 sec.

Best,   DennisT
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Offline Dan McEntee

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #3 on: October 30, 2018, 07:22:00 PM »
Quote from: John Craig on October 30, 2018, 08:33:00 AM
A nice running FP 25, stock muffler, 10-4 prop, on a profile RST, launch 10,400, wide square wedge  3.5oz tank on uniflow pressure, level flight after bailing out of the overhead 8 the engine runs fine for 7 min, leaning for only the last 3 laps, I kicked the rear of the tank out 3/16 with no change, line tension is fine.

Suggestions?

Chicken Hopper?

All help is appreciated.

   Pop the back of the tank off and check out the pick up tube, along with the rest of the innards. If you have a set of lines a foot or two shorter, try those. Line tension may seem fine, but if if it sags at all, you loose your fuel pick up. I had a similar tank on my Sakitumi that worked fine for several years (metal) and  all of a sudden did the same thing. Either it quit in the overheads or clover, or if I put in an extra 1/4 ounce, I over ran! I plumbed up a 4 ounce sullivan plastic tank the way I like to use them and all is well now. One of these days I'll pop the back off the tank and see what changed.
  Type at you later,
   Dan McEntee
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Offline John Craig

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #4 on: October 31, 2018, 06:54:06 AM »


Also, 7 mins seems like at least a minute longer than needed for the PA pattern, what line length and lap time are you at? Normal for a smaller ship on 60' lines would be around 4.9 sec to 5 sec.

Best,   DennisT
[/quote]

Thanks for the help!   #^

Yes, I am at 60' & in the 5 sec range. I will first try the no pressure (Yoda has also suggested this in the past) while I plumb a plastic tank.  Then give the plastic tank a try & check the innards of the current metal tank. Perhaps a baffle in the metal tank?

JEC
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Offline Steve Helmick

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #5 on: October 31, 2018, 09:11:48 PM »
Excess yaw is often a cause or contributor. Take a look down the LE of your Flite Streak or Ringmaster, or sight down the flap hingeline on the typical stunter with a straight hingeline. I'm not sure what an "RST" is, or if the LE is straight or not. If neither the LE or hingeline works for you, put sighting marks on the inboard tip and fuselage side.  D>K Steve





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Offline Dennis Toth

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #6 on: November 01, 2018, 08:18:35 AM »
John,
Have you changed the %N in your fuel. For some engine setups this can make a significant difference in run time, simply going from 5% to 10% can do just what you describe, but this would be cured with a bigger tank.

Please update this thread once you get the solution so others will know how to setup their ships to start with.

Best,   DennisT
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Offline Target

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Re: engine cuts out or stutters in last 2 maneuvers
« Reply #7 on: November 01, 2018, 09:11:31 PM »
Quote from: Steve Helmick on October 31, 2018, 09:11:48 PM
I'm not sure what an "RST" is, or if the LE is straight or not.   D>K Steve

RST is Rugged Stunt Trainer.
I think that Phil Cartier is the one that sells them.
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