Hi dear colleagues!

I have a Fuji 50 EIS and I am running a 22x8 prop on it. It turns it at 6450 rpm. I think for this engine is very good. However my GP Yak-54 even at lowest throttle flies with a constant low speed, so the landings are a bit difficult. When I saw on the tach the low rpm's were 1920. I think they are high. Also I tried to reduce them but the engine hesitates and most often stops if they go below 1800. I read that the Da-50 can make 900-950 rpm, which is amazing for me. I don't believe the difference is so big. Maybe there should be some tip or tunning trick to make the engine more stable at lower rpm and also to reduce them so I land easier.

Waiting for your answer and suggestions!

Best regards!

You need to find out where some folks buy their tachs. Then you can get relly high and low rpm readings too.
For landing you have to learn to cool the engine down a bit setting up for landing so it goes to idle easier, Make longer approaches, And perhaps tune it a bit richer on the low needle. A wetter idle will help cool the engine faster leading to a quicker transition to lower rpms.

A 22x8 is too much prop for that engine. I fly with a 20x8 and get 6800 or so rpm. Never, NEVER, believe rpm numbers you see on the forum! I am convinced that half of them are questimation and the other half have very generous tachs. For instance, g-62's at our field running 22x8 menz props might get to 7100 to 7200 max. Now I know they will be down a few hundred rpms at our altitude, 5,000 feet, but I see posts all the time where guys are getting that kind of rpm with a 24x8. The other thing that makes me laugh are rpm numbers where changing a prop gives 20 or 30 more rpm. I don't know what kind of tachs are being used but they aren't that accurate. By the way I use an old Royal pro tach that is considered one of the best ever made and rpm readings aren't that consistant.

Larry

First a 20x8 or 10 is plent of prop for that engine. Check that you don't have any airleaks under the carb, and like altavillan said richer will idle a little better. I also use the idle down feature on my Futaba radio, you set your idle for flying where you know it will never die, (a little fast), then when I'm landing I flip a switch and the idle is set 100~200 rpm lower so I can land, if I have to go around I slowly advance the throttle so it doesn't die.

Hi!

Thanks for the answers! I am doing the same. I have programmed the THROTTLE-CUT button to reduce a bit the rpm's. However I'll try making the engine run on lower rpm's without dieing. I plan to remove the Bolt which is the limiter of the valve. There is actually no need of it, since the throttle servo holds the throw at a exact position according to your own settings. Also it might be good when landing to adjust to servo to go to fully closed position so it actually could reduce rpm. Well I still haven't tried with a 20x8 prop for my Yak-54. I want it to hover and to have unlimited vertical power, but I remember that with a 20x10 it couldn't hover well. So I think that with 22x6-8 there will be more effect. Also I have flowed
the Yak-54 with a 22x8 MARO prop.

Regarding the tach I can guarantee for its readings that they are correct. So I think 6450-6500 is pretty well. It still has to break-in some more.

So as far as I see from your suggestions, I'll have to make the lower rpm needle richer. I'll do that. But is there any idea how to make the lowest rpms at 1400-1500 if possible?

Best regards!

I've found that with a 8 pitch prop 1800 rpm is good for landing. I have a MT50 that can idle at 1100rpm, but there's no reason to do that, 1800 rpm is 0 thrust at landing speed.

You can calibrate you electronic tack by pointing it at a light bulb 3600 rpm in the USA with 60Hz, 3000 rpm if you have 50Hz.

Hi!

Well like you see with the Fuji the things ain't like that. It always pulls the plane a bit even at the lowest idle position. So this is why I think I have to reduce the low rpm's a bit.

Best regards!


P.S I didn't understand the last thing you have written . I am from Bulgaria and our electricity characteristics are: 220V @ 60 Hz. How 3000 rpm are related to the frequency?

He's refering to flourescent lite tubes. Point your tach at a tube here and it will read 3600. On european currant it will read 3000. Sounds like you have the same current as here.
As far as getting the lowest idle, bypass engines will not idle as low as reed valve engines because of the turbulance and tendency of the carb to spit fuel on the bypass engines. Tuning and tinkering, and adding a velosity stack will help, and an airfilter to cover the stack. As the idle gets lower so do the vibrations get more violent on the airframe. So only go low enough to land safely.