hey, my supersports 40 with an OS 46 has been sitting for 3-4 months. I took it to the field recently, spent 10 min. tunning it for best perf, and attempted taking off with no luck. It barely had the power to get off the ground, and when it did it stalled and went down. This happened several times until i eventually gve up for the day. Could the carb be gummed up from sitting? is there something else i should look at ??

when the plane is sitting on the stand does the engine sound about right?

my guess would be that its either to heavy or your CG is off.

You may have picked up a piece of dirt or something, but I doubt that 4-5 months sitting would creat any problems other than posibly stale fuel. Flush it out and try again.

shake your fuel and hold it up to a light. If it has white precip in it, its gone. Could be bad fuel or crap in the engine. Change the plug too.

what did the engine tach out at?

Sounds like it's still not tune in yet

What stalled, the engine or the plane? If the engine "stalled", perhaps you set the needle too lean. Did you point the nose of the plane in the air, with the throttle at full, for 5-10 seconds to confirm the engine was not too lean?

Was there fuel in the tank while it was sitting?

If you cannot get it to tune/run properly, take out the fuel tank, remove the stopper and check for debris. Also check for corrosion of the metal fuel tubes in the tank. Flush out the fuel system (including carb) and have another go at it. I usually take the carb apart and ensure that all debris is cleaned out - I flush with alcohol and blow out the system with low pressure air from my compressor. I am assuming that your glow plug is good. I used to have this problem a lot - I could not believe how quickly the fuel system can get gummed up. Of course this has a lot to do with fuel quality and storage conditions, but in my case, a few months would do it. Now when I am done flying a particular bird for a while, I fill/flush the fuel system with clean alcohol and then dry it out with compressed air. Hope this helps.

Steve

Very high humidity levels are normal locally, and have caused problems for several of our club members who had 2 - 6 month interruptions in there flying. In all cases they had not ensured their fuel jugs were completely sealed.... so, they had moisture get into fuel jugs. The symptoms you describe match what they experienced. Check your fuel to see if it is cleanly transparent, or if it seems cloudy or murky (which indicates water has been absorbed into the fuel).

Hi!
You have to tell us more...what prop size do you use, rpm etc.
Regards!
Jan K
Sweden

Hey, thanks every1 for the replies and sugguestions.
Sorry, i should have been a little more specific and given more details. My plane is a supersports 40 which i built and bought a non-bearing 46 sized os with 10x6 wooden prop. I have had nothing but successful flights for a half year prior to the sitting period. But after that its been running very inconsistent, wants to die while taxxiing, unless i stay on the throttle, and then of course insufficient power after take-off. It either just dies right after take-off, or runs so poorly that i lose airspeed eventually leading me to stall the plane. I DID leave fuel in the tank while sitting which wasnt smart. I will certainly clean the tank and then the carb, buy some new fuel and see what happens. If still no luck, maybe i should just buy a new engine?
-Jamie

Hi!
You are running the wrong prop and you are running the engine too lean. That simple.
Put a 11x6 on and open the highspeed needle some...always hold the nose of the airplane up and check if the engine could hold its setting in this position...if not ...open the highspeed needle somewhat more.

Regards!
Jan K
Sweden

Ok i will give an 11x6 prop a shot. also, i didnt hold the nose up to check it's settings. I will go out and give it another shot and let ya know what happens....thanks
-Jamie

Jamie,

It is hard to tell you exact problem without seeing the plane and engine, but here are a couple of things that happen when your engine sits for a while. First, the tank plug on ARF tanks is made of fairly hard rubber. Many of them get harder and lose their stretch and just fall out. Some get loose and let muffler pressure bleed out of the tank. The worst case is to have the plug come out inside the plane with a full tank of fuel. If you can get ot the tank, grab the plug and brass tubing and give it a tug.

Another thing that can happen is fuel in your needle valve evaporates leaving the oil residue behind. This coats the inside of the fuel jet, changing the orifice size and your mixture setting. As you run the engine again, this slowly washes away and your engine runs fine again. Don't go changing very much except to open the needle a few clicks so you aren't running too lean.

As for the prop, a 10-6 is a little small, but a lot of people run them. It wouldn't be my choice for any .46, but it's in the ball park so if your plane was flying OK before, it isn't the prop. A 10-7 for speed or an 11-5 or 6 for climb power would be a better choice.

I use an APC 10X6 on my TT 46's. They work very well. From the sounds of it my first thought was that the engine is too lean. You did say you tunned it for best performance, you should be a few hundred RPM rich of peak. Other than that I would definatly change fuel and check your fuel system looking closely at the tank and clunk.

another quick question...since props were brought up... Is there a certain size prop which could help to slow an airplane down or fly at lower airspeeds at low throttle? I'm asking because my supersports 40 would always come in a bit fast for landings even with min. throttle making them alittle tricky. There are no flaps on this plane and uses 1 servo for alireon contrl, so flaperons would be out of the question. Would a larger prop or any other prop for that matter help lower airspeed, or do i just have to deal with these characteristics?
-J

A larger diameter prop with less pitch would help to slow the plane on landing.

I have a SuperSports and it does like to come in a bit hot. I actually prefer this because it keeps it coming in at a steady pace even in windy conditions and really reduces the chance of stalling when landing.

yea, this plane is really hard to stall on apprach which is a plus, alittle more difficult to touch down smoothly. I usually cut power on downwind, and it still manages to come in fast on final. they really just need flaps. what engine do you have on yours?
Anyway, as it turned out, my engine was jus not tuned right. I spent about 10min today trying to set it perfectly, and it ran well...for me, nitro engines seem easier to tune in cooler weather. and run more consistantly... not sure why..

Hi ironj21, I have a 6 year old FX46 which still runs like new with an APC 11-5 on the nose. The plane is very fast with this prop so I am interested to see what it will do with an 11-6 and 11-7. I haven't had any problems making smooth landings but thats probably just from lots of stick time. I have 7 planes now and retired 5 or 6 others before that. [8D]

Fastsky, going to 11X6 or 11X7 will give more speed, not less. If you are getting fast landing speed with the 11X5, re-examine your balance point. Some nose heavy condition is OK, but too much forward balance will produce excess glide speed. If you can move the balance aft and still be in a good balance range, it will help slow down the landing.

Hey Jim, the hot landing speed I am talking about is a relative term. Its a lot faster than my LT25 for example but certainly isn't a problem and all my landings have been very smooth. I had another plane that would land very hot until I learned that it like lots of up elevator to slow it down and would then land at a crawl. I got the plane near the end of the flying season and haven't had the plane to the field more than a few times. The plane may land a lot slower but haven't hadmuch of chance to experinment. Need warmer weather now! []

Fastsky, you have that right! Elevator is the speed control on landing. Engine thrust is the altitude control. Happy Landings!