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solving poor power / performance issues

10 posts in this topic

Posted

I'm just starting a new thread over here as I was taking away from the original post on the other thread. 

 

That said I have adjusted the flapperons and added some weight to the tail spring. It is already flying much nicer however the performance still is not that great. But I think we are on to something. I went up this morning with my wife for about an hour. field elevation 4000' OAT at T/O was about 60* climb out at 6300 rpms and 60 MPH indicated was 400-450 FPM and cruise at 6300 RPMS was about 75 MPH Indicated. throttle settings on T/O was full power and at cruise I was pulled back about half way to keep from over running the engine. That said My next test when I can fly back to the flat lands will be to flatten out the prop for best climb and record numbers and then re adjust for best cruise and test it again. I'm pretty sure those numbers will be looking more like what I would expect. if so the best solution I can see would be to add an IFA motor to the prop :) water temp with some duck tape on the radiator is still low at about 115* not sure if the cold temps are robbing me of power or not. the new thermostat didn't make much difference in getting it up. may take me a week or so to get more testing done but I will post my results when I have them. 

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Posted

I would wonder about the water temp gauge. If you have a 135 degree thermostat, your temp should at least get that high. Don't remember if you have an Avid or Kitfox, but Avids are usually a bit hard to keep cool enough. Jim Chuk

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Posted

Minimum water temp for flight on a 582 per the Rotax Operator's manual is listed as 150 F. 115 is too low and I suspect your reading is way off. What kind of gauge are you using? The Westach quad gauges are notoriously innacurate, though more often with the EGT's. I had a Rotax water temp sensor go bad on me too. You could pull the sensor and calibrate against a thermometer in a hot water bath to see if you're in the ballpark or not.

If your temps really are that low, bad things could happen such as cold seizure, leading to piston scuffing.

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Posted

I'm running an MGL engine monitor. might have to try and double check the sensor make sure its correct

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Posted

I wouldn't be in too big a hurry to reduce pitch,75 mph 6300 rpm is getting up a bit

1 degree less pitch would see approx 6500rpm for the same cruise for possibly not much gain in take off or climb

I assume your prop tracking and pitch settings are all bang on?

A little bit off makes a big difference

Start with the simple things

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Posted (edited)

High Country,

     If you are wanting stol and climb, I think the 72" prop like Akflyer uses would give you better performance, and again, cruise might not be as good by maybe 5 mph, or maybe not?   

     I am also wondering about you having to throttle back 1/2 throttle to keep from overreving in cruise might be a sign that something is not right with your setup? 

     Is this normal operation for the 2-strokes?  Sounds like not enough prop or pitch for cruise?

     I wouldn't know what climb and cruise figures would be right for your high altitude.  I normally don't even cruise as high as your ground level.

    but guess you need to check your temperatures before going farther.

     It would be nice to see some figures if you could borrow a 72" prop or blades for testing before going IFA.

     My WD wont work for your engine, or I would offer to loan it to you.

Sorry I cant be more help - Got to let the 2-smoke experts work with you on this.

EDMO

Edited by Ed In Missouri

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Posted

I wouldn't be flying it with 115 degree temps.  If you cant get them up higher than that, you need to put another strip of duct tape in the radiator.  I don't give mine full power till I am seeing 140 on the gauge, but I run a 160 thermostat on mine.  I got one of the inline thermostat housing from high wing LLC so I can run a thermostat from the auto parts store thats only 12 bucks versus the Rotax dinky thermostat that is 120 + bucks.

 

What color are you plugs... I initially set my cables on the oil pump per the marks, but when I measured the actual oil used versus the gas burned I was consistently showing 40:1 on the oil consumption on CC trips.  My plugs were getting fouled about every 25 hours or so.  I slowly adjusted the cable till I was getting a 50:1 burn average on the CC trips and my plugs now look good and I picked up a few hundred RPM.

 

Pull the cowling off and warm the engine up on your old plugs, then shut it down, swap to new plugs and fire it up.  Go to full power on the ground for about a minute or two then shut it down quickly, do not let it idle more than it takes to shut it down.  Pull those plugs and look at them to see if you have a nice tan color.  The plug reading is going to be the tell tale on your jetting and oil settings.

 

:BC:

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Posted

Leni,

     If his engine don't get up to proper temperature, will this test still work?

EDMO

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Posted

yes, the plug reading is air / fuel / oil test.  First thing I would do though is keep putting tape on the radiator till you get the temps up to 140.

 

:BC:

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Posted

Thanks for the input, I will try and get the temps up in the morning then do Leni's test to double check all the mixtures. When we first got her flying last October we had a GSC prop that later became its own issue but when it worked the performance was much nicer, I hit cruise speeds of 100 indicated and double checked with another aircraft. Climb was much better too so I know the plane is capable of much more. Hopefully I  will know more soon and will post up the progress in the next couple days. 

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