awat65

My Feedback: (17)

I have a Funtana with a Os 108 on it. The motor is new witha Bission pitts style muffler. After 5 min of flight, the motor died. once back on the ground the motor started on the first flip. I checked to see if the motor was lean and it was not. On the second flight, on take off the motor died again. I changed all the fuel lines. does anybody have any suggestions on how I can eliminate the engine dying?. Again the motor is new.

Not24

My Feedback: (1)

I need to assume that the engine has been broken in at least for 3 tanks of fuel before you tried to fly it. Other than that, there are many variables. It would be senseless for me to try to diagnose your problem till I know everything about the setup and previous run time on the engine. I'll just list them for you, and you fill in the answers.

fuel?
prop?
the tank is located where?
glow plug?
idle setting on carb?
high needle setting?
idle rpm?
max rpm?
flight rpm setting?
total time on engine?

Try to answer as many of these as possible.

My setup works perfect, although I am pulling the 1.08 to use in another plane. I have a perry vp-30 pump running with a bypass line, the tank is behind the tube, bisson pitts with both ports wide open, apc 16-6, powermaster 10% with synthetic/castor blend,idle all day long at 1800 and wide open is just over 9000, set to 8800 to fly. All fuel line is medium tubing because the pump provides plenty of volume.

My engine seems to be a few hundred rpm low compared to STG, but it still flies the plane very well. I'm sure he will chime in on this one too, as he has helped me get mine running as good as it does.

jerryjjenkins

I have a showtime with a saito 150 that had the some problem. My problem was that I had a pressure leak in the fuel system. I also changed to a uni-flow tank fule system. Try a tank and line pressure test. Clamp the fuel line at the carb. Blow into the line from the muffler and clamp wait five minutes and the release the line again your cheek and you shown fell and hear a pressure release. If not you have a leak some where, which causes the engine to run out of fuel on a g pull.

STG

My Feedback: (26)

Yes, please try to fill us in.

I know you want to get the plane in the air, but make sure you spend enough time on the ground trying to work the bugs out before you put it back up. Make sure you are running rich with the 1.08 ring motor. A good rich fist couple gallons ring seat will pay off with good power for the life of the motor.

K.O.

My Feedback: (16)

I had a similiar problem with a plane ( engine quit right after take off) I've flown for 2 years with out any engine problem or engine quiting for no apparent reason. Once I have an engine dialed in I almost never change the settings or fuel. What I found in this case was the fuel supply line inside the take had broke off so when I took off (I usually go vertical) the engine quit. When I hear of this kind of problem I always suspect it is a fuel feed issue.
One thing you might try is hold the plane at various attitudes with the engine running to see if the engine continues to run. Thats how I discovered my problem after the 2nd flight attempt. Hope this is of some help.
K.O.

Balsa Steel

My Feedback: (3)

How did your O.S. 108 powered Funtanas balance? Before radio and battery installation, did they balance more toward the tail, or the nose?

awat65

My Feedback: (17)

The motor runs fine now. It was rich. I leaned the motor out a bit and it runs fine. I now have 10 flights on her. I do not know how it balanced with out radio equipment. I just put everything forward and the CG is right on the recomended mark.

Balsa Steel

My Feedback: (3)

Everything forward... OK. Does the 108 pull it satisfactorily? Have you weighed yours?

Rifat

Hi!
For the ones who are flying with os 1.08'sost your prop/tach readings with nitro percentages and RTF weights.
And I want to ask sımething more:Is 1.08 enough to pull out from a hover?


Rifat Kmaisliogullari

STG

My Feedback: (26)

See http://home.comcast.net/~stgflying/INDEX.HTML for short film clips of the 108 on the F90

If your F90 is running like mine it is enough to pull from hover. A typlcal F90 will come in @10 pounds. Expect a 1.5:1 power to weight ratio...not a ton of get out of trouble power.

I think the FX160/st2300/MO135 are better power choices for this bird.

Well today was not a good fly day—too rainy and windy, but I did go out and get some thrust figures. The test was with a F90 with OS 108FSR , Jec pitts muffler, restrictor sleeve removed from the carb and VP30 pump. Fuel used was Cool Power 15%. Temp 51° Humidity 76% and dupoint was 44°. I used a Rapalla fishing scale that calibrates within 1oz at 10 and 15 pounds. Elevation is at about 300 feet.

I tried six different props and to my surprise max thrust was very close between them. The props are shown below in the picture and are ordered left to right lowest to highest thrust. My measurements were rmp at 10 pounds (about hovering rpm) of thrust and rmp at max rpm/thrust.


Prop RPM at 10 pounds Max RPM& Thrust
15 x6 apc 8,900rpm 10,600 – 13.7 pounds

16 x6 zing not measured 9400- 14.6 pounds

18x8n apc 6,400 8200- 14.9 pounds

16 x5 c zing 7,900 9800- 15.1 pounds

16 x6 apc 7,700 9520- 15.2 pounds

17 x6 apc 7,100 9,200- 15.5 pounds

All these peak readings are about a 1.5 pounds better than I expected. Not sure why this is?

I am extremely happy with the way the motor runs and transition is outstanding. I made a recording of it at the end when I had the 16 x 6 zinger on. Anyone curious to how fast this 2 stoke transitions please email me and I will send the wave file to you.

coveredup

My Feedback: (1)

May want to make sure that none of that gravel is going to get caught in the prop! [:@]