Blade-breaker

My Feedback: (4)

Hey everyone,

I have my first Gas engine plane flying now and I am loving it, but I have a concern about the operation of the engine. I am not sure if this is normal for a gasoline engine or not.

While flying, lets say at full throttle, putting the plane in a steep dive the engine rpm naturally increases. But once the engine rpm increases to a certain point the engine stops firing. When the plane has leveled out and the airspeed and rpm has decreased the engine starts to fire normally again at full throttle.

The same thing happens when diving with the engine idling. The engine stops firing when the rpm increases, once the plane is leveled out and the air speed and rpm comes back down to close to normal it starts to fire again. When this happens it doesnt pop back fire nothing, just sounds like you are spinning the engine with a starter motor. When it does come back to life (idling) it doesnt sound right to me. It has never died on me yet, but it worries me!

Even my little glow engines will pop and fire ocasionally while idling and diving, and they never stop firing while at wide open throttle and diving.

Is this normal for gasoline engines???

Thanks!!

karolh

Never heard of that before so I too am curious as to what could be the cause of that happening, if in fact that is what is happening. Just for the record what brand and size prop are you using?

Karol

Blade-breaker

My Feedback: (4)

I am using a APC 16-8 prop.

A guy at the local hobby shop said its got to be the fuel pick up line being to far back. I can hold the plane nose down and the engine will run wide open for quite a while before it runs out of fuel. I would say this is not the problem.

He also mentioned it could be too lean. I will adjust the mixture again tonight, but I have tried it running rich, so rich it was quite low on hp. Same thing.

karolh

As I see it if the engine stops firing then there is no combustion taking place so the engine / prop should stop spinning due to the compression. Without an onboard starter there is nothing that will restart the engine, so possibly the engine never stopped, it might just sound like it did.

Karol

Blade-breaker

My Feedback: (4)

I agree with you, it just sounds funny to me. I was wondering if that is a normal sound for gasoline engines. It is quite a bit different than the sound of a glow engine in a dive. I talked with Terry I do believe his name was from CH ignitions today when I ordered his ignition for my engine. He was very helpfull with a couple questions I had about this engine. He also mentioned that he has heard of others being concerned with the same thing I am. He mentioned that there should not be anything to be concerned with. VERY NICE GUY!!

Thanks

karolh

Terry is a very nice and knowledgable person to deal with wether it is about his (CH) ignitions or something to do with our engines, and if he thinks it's nothing to be alamed or concerned about I would leave it right there.

You never mentioned what model you were flying or how much it weights, as it's almost the norm to use an 18x6 prop as the benchmark for the G26. Maybe you should try one and see what happens, just adjust your needles to suit.

Karol

Blade-breaker

My Feedback: (4)

I have the G26 on a Ultra Stick Lite, I read the post Ultra Stick Done right about moving the firewall back 3". I shortened mine 2.5" and it came out ballanced just perfect. I am very thankfull to the persone who pointed me in that direction! I have a 18-6 prop in my hangar, I will try it out.


I started with the 16-8 just because the Zenoah book says thats a good starting point.

Thanks for your thoughts!!

Ryan

karolh

I use a 16x8 on my G23 which is normally about 800 rpm shy of a G26, but a thought just came to mind, are you using the stock 'quiet' muffler on our engine?

Karol

Blade-breaker

My Feedback: (4)

Karol, you were right about the 18-6 prop. It is much better, although the one I am using is a 18-6 Wide, I think it may be a touch too much for the engine. I really need to get a tachometer so I can see what it is spinning. There is a 17-8 prop in my tool box i may try that one next time out. I made about 10 flights today with the plane.. WHAT FUN !!!

With the 18-6 prop on the plane diving while at full throttle down to about 1/4 throttle the engine sounds normal, revs up and still makes plenty of exhaust noise. Diving while below 1/4 throttle still the engine goes silent until the rpm drops back down.
One thing to note is that the engine has never died, When it comes back to life after a dive at idle it sure sounds like its going to but doesnt.

Yes I am using the stock muffler on the engine. Would you recomend something else?

Thanks
Ryan

arobatx

You will gain significant RPM by replacing the stock muffler with a suitable aftermarket alternative. Karol may also have been asking because the stock can muffler is VERY quiet, the one thing it is good at

karolh

The 18x6w might not be too much prop for the engine, it depends on the numbers, but a 18x6 would be ideal. Arobatx is correct, as an aftermarket muffler is much lighter, gives much better performance and though louder might be the answer to your mysterious engine silence, as I think that the very quiet nature of your stock muffler is killing the sound of the engine's exhaust when in a high speed dive at a low throttle setting.

Karol

arobatx

totally agree...the quiet muffler and pitch of the prop at certain degrees of no-power dives will make the powerplant stealthy I'd be surprised if you wouldn't see a 600-800rpm increase in RPM by changing the muffler to something more free flowing (but loud), like the AbellRC muffler. The Slimline pitts is a good balance between RPM gain and sound if you'd like a more balanced upgrade. Just remember to retune with any prop/muffler/oil changes you employ!

Chad

karolh

Ryan, act on this advice and your FUN level just went up a couple notches, no joke [sm=thumbs_up.gif]

Karol

Blade-breaker

My Feedback: (4)

Karol, Chad,

Thanks for the advice about the muffler! I am going to do some shopping for a aftermarket tonight. Ill check out the AbellRC and see what it looks like. I also am going to get a 18-6 prop, and a tachometer so I can see what rpm its turning.

I like the sound of MORE FUN!!!! YIPEEE!!

Thanks guys!!!!!!

Ryan

arobatx

Since you've opted to go shopping....please do consider the Mezjlik 18x6 carbon prop! I have yet to experience or hear of a better performer on the 26. They aren't cheap, but SO worth it

karolh

Those Mezjlik CF props really turn up the heat and perform, but are a tad to steep in price for my pocket, so for now I use standard Xoar beech props which are very good performers themselves.

Karol

Blade-breaker

My Feedback: (4)

There was a 17-8 prop hiding in the bottom of my tool box, that seems better than the 18-6w. I ordered a few different props last night. Thanks for the reccomendation arobatx, but I went with some less expensive apc, and beech wood props. I will maybe order a Mezjik CF prop once I get some more hours on the plane.

Anyone reccomend a aftermarket muffler brand that would be good? I looked on the AbellRC site and didnt see anything for the G26.

Happy flying!!
Ryan

karolh

It is strange that the Abell site only shows one for the G62, anyway I would give them a call just to check. There are however other good alternatives such as Bisson, Slimline, Jtec, Bennetts and possibly Brillelli, as their 26SS and the G26 have identical mounting etc.

Karol

karolh

I just spoke with Clay at Abell RC and he advised me that they have made some changes in their manufacturing and have discontinued the Zenoah mufflers. He said they are now only making units for the more popular brands like 3W, and here was I thinking that the Zenoah brand was a very popular one ... well that just shows how much I know about being popular.

Karol

Murphey

My Feedback: (11)

Check out Chief Aircraft...the link below takes you to the mufflers...scroll down to Zenaoh. There you will find a Slimline Pitts...perfect for this engine and as good a price as anyone too!

http://www.chiefaircraft.com/rcmsec/.../Slimline.html


Murphey

karolh

Do Pitts style mufflers as a rule give better performance over the basic inverted type mufflers.

Karol

Blade-breaker

My Feedback: (4)

Thanks for the information!

I will have to do some research and see what route I want to take.

Changing the prop on the plane will hopefully give me some added performance, then I will try a muffler after that.

arobatx

...don't forget to retune the engine with any muffler/prop change!

Blade-breaker

My Feedback: (4)

You bet! Thanks!!

mcbrideb