RC Pilot Sbach 342 87"(50cc) - RC Groups
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Sep 16, 2011, 07:11 PM
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RC Pilot Sbach 342 87"(50cc)

I finished and flew this plane for the first time. I used factory recommended throws and expo setting plus factory recommended CG (rear side of the wing tube). It flew pitch sensitive or kind of like tail heavy. I couldn't understand because the flight was too short. In less than a minute my engine quit for unknown reason and I had to do a dead-stick landing. It was terrible!.. The plane almost lost its flying ability right after engine quit. The landing was harsh. I fixed the plane and will fly it again but looking for some recommendation/advice from RC Pilot Sbach 342 (50cc) owners on CG and elevator throws/expo...

-Does this plane have a tendency to go into stall immediately if the engine quits?
-Is factory recommended CG and throws accurate?

Last edited by iskoos; Sep 16, 2011 at 07:24 PM.
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Sep 16, 2011, 07:27 PM
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kerwin50's Avatar
I would balance it just in front of the wing tube to start with.
You can always move your cg back.
It's alot easier to move your CG back than it is to move it forward.
What engine were you using?
Sep 17, 2011, 05:22 AM
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Front of the wing tube is kind of what I was thinking. I am using Mintor 55 engine and this engine seems much lighter than other (DLE, DA, Zenoah) common engines. Mintor is made of aluminum alloy and it looks and feels really different...

I am pretty sure I won't find anyone else here with the same Sbach 50cc & Mintor 55 combo. Although it is very nice engine, not many people using it...
Sep 18, 2011, 06:07 AM
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Hi, I did fly the sbach yesterday wit the CG at the front of the wing tube. It was pretty nose heavy after take off. I had to dial 3 up-clicks on the elevator. But the airplane was feeling solid in the air. I landed after a few minutes and removed some weight so that the CG is at the center of the wing tube. I took off again. It was better this time. Mintor 55 was running rich but I am in the break-in process, I let it run. We flew about 10 minutes and then landed. During both landings, I observed that throttle must be at least at 1/3 till almost touch-down. It is a heavy airframe and cannot handle approaches with throttle is at idle (unless you have some steep approachs to keep the air speed up).
Now, I understand better why that dead-stick landing (into 10mph wind) was terrible...

My conclusion:

- Factory recommended CG might feel a bit tail heavy if you are not used to 3D style airframes (Like me). So keep in mind...
- Control surfaces (especiallay elevator) feel super sensitive, make sure to dial enough expo or you might be in trouble... I would recommend more than factory recommended and then reduced later if you don't like...
- This airframe does NOT like gliding per my experience. So make sure to keep the engine running all the time. My first dead-stick hurt!..
Sep 18, 2011, 09:41 AM
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kerwin50's Avatar
Glad to hear she is up and flying
Most 50cc planes have a braking action due to the large prop so you need to fly them different than planes with a smaller prop. IE keep the power on

Also gas engines are alot different in the respect that you do not run them rich for break in,all that does is foul sparkplugs and carbon them up. a good tune mean everything.
Sep 18, 2011, 10:18 AM
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Yeap... This is my first gas airplane experience. I built this for a friend actually. The engine is running but it is running rich. This is obvious. You don't realize this at full throttle but around mid (or just below mid) throttle, engine sputters a bit clearly showing that it is running rich. Both needles are factory set for the Mintor. Since I don't know much about gas engines, I didn't want to mess with them. I just recommended that the high should be leaned out (by maybe 1/16 - 1/8) to make the engine happy...
Also we are running a bit smaller prob than recommended. Manual calls for 23x8", we were able to find 22x8"
At the current needle setting, it tops out at 6700 rpm and the idle goes as low as 2200 rpm... I am pretty sure, she can do better than this...
Sep 19, 2011, 12:56 PM
Registered User
kerwin50's Avatar
This is a very good link for tuning gas engines

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