Lnewqban

That may have been a sign of the engine being improperly tuned, which would be another reason for the weak thrust during take-offs.

http://www.google.com/url?sa=t&rct=j....b2I&cad=rja\\

http://www.google.com/url?sa=t&rct=j...,d.b2I&cad=rja

I believe that this is important for you to understand:

http://www.rcuniverse.com/forum/aero...tall-spin.html

Jim Thomerson

Back when I was serious about control line stunt, I was flying a Fox stunt 35 with the usual 10 x 6 propeller. I decided it was not accellerating out of square corners like I wanted it to. I put on an 11 x 5, I was flying off a stooge. When I pulled the stooge line, I found myself flying about ten feet behind the airplane because of the greater accelleration from a standstill, Worked to suit me, and I have been running 11 x 5 on Fox stunt 35s ever since.

wikitjuggla

well I check the tune every time I fly and usually have someone there with me to make sure I have it tuned right and even on warm days where the engine is running perfect, I still need the whole strip to take off but that particular day I probably should have had a hotter plug. I've never used anything else but a medium temp plug in it. Haven't had anyone show me how to fiddle with different temp plugs. I'm gonna test out the bigger wheels and 11x5 prop on the 1st of the year for my clubs fun fly, weather permitting, so I'll let everyone know how that turns out. Maybe they will have rolled the field by then too

BMatthews

I've never had to change the heat range of the plugs and I'd suggest you don't need to do so either. What I did find is that if I'm running a low or no nitro fuel that upping the nitro content to a fuel with about 5% more nitro helps with starting and getting even runs on cold winter days.

The important thing when setting the needle valve is to run it up to the peak RPM and then back off about 1/2 to 3/4 turn to a richer setting. This way when the model gets into the air and the RPM climbs thanks to the prop unloading slightly it will not be running too lean. Usually a rising and falling cycle of the RPM indicates a lean setting. Also setting the RPM back a little richer off the peak then holding the model up at a 45 to 60 degree nose up angle at full throttle is a good check to make sure the engine can still draw the fuel up to the carb correctly. A lot of models put the fuel tank too far back, too low or a combination of both. With the tank installed like this they might run OK while flat on the ground but during any sort of climb the engine leans out due to difficulty in drawing up the fuel from the now overly lower tank.


The other common mistake is to try running the engine on too big a tank. Again this makes it so the last of the fuel has to be drawn from too far back and down to ensure that the engine can get a consistent run through the whole tank.

wikitjuggla

I'm running 15% nitro, 18% synthetic/castor oil blend. I might have had it out of tune. They trained me to hold it up at about 90 degrees and if its tuned right, the rpm's will pick up slightly. After that trouble I didn't even bother with it. Just cleaned it up and called it a day. It was way too cold to be fiddling with needle valves behind a cold air blowing prop and I was flying by myself that day. Its an old engine and the guy I bought it from had never ran it in a model and i've put a gallon on it already in my Nexstar. Its way more faithful of a motor than the SH .21 in my nitro car that has been nothing but a pain since I opened it from the box