ORIGINAL: gaRCfield
My thoughts, definitely before considering a new engine:
The .55AX should be more than enough power for the .46 Reactor. The .55 was designed to fit in .46 planes to give them more power. As others have mentioned, 2-strokes need more throttle (rpm) to hover a plane than 4-strokes with their increased throttle response and torque.
Though it was designed for a 46 engine, that would only give sufficient power for sports flying. The FS72A wont be any better, it would give the power of a 46 size 2C (2/3 SIZE)
ORIGINAL: gaRCfield
-I think 13x5 would give good vertical performance on that engine in that plane. I have a 12x8 in mine for aerobatics.
-I did notice in the GP video they are flying the 4-stroke .70, but the .55 should give you more power, just with more RPM.
I noticed with the 12x8 that aerobatics were quite good and the engine was running well. With a 13x4, the engine did not have compression after running a few minutes. It did not have the airspeed for any pattern flying either. When I landed I found that the engine could turn over without any perceptible compression. After it had cooled a bit compression was back. This happened repeatedly even with the 12x6. I presume engine is overheating. I have the engine tuned ok, half turn rich from max rpm. I didnt however tach or check the temperature
ORIGINAL: gaRCfield
I would try more nitro (15-20%) and less oil (18%).
-2% more oil means 2% less fuel.
It it overheats at 10%, it will have more problems at 15-20. I dont want to put that much nitro in it anyway
ORIGINAL: gaRCfield
I wonder if the problem lies in the engine tune. Hovering is probably the hardest thing on an engine - high power, no air flow, and demanding fuel vertically against gravity.
-Check the tuning of the idle valve; most people seem to try to attack tuning with only the HSN, but it is a 2-part system. You're getting hot and lacking power, sounds like fuel draw is an issue in vertical attitude.
-Run the engine on the ground. Advance to full power, drop to idle, and watch your RPM. They should stay constant for a good 20 seconds. If you see a gain in RPM, your idle valve is lean. If you see a decrease, your idle valve is rich. Adjusting one means you have to go and check the other; it is an iterative process.
My LSN is a bit rich but not by much, may be by 1/8th or 1/16th turn. In any case, I dont think that will affect the hover. If I need to put in 100% power just to hover, where is the spare for pullout?
ORIGINAL: gaRCfield
-Check your fuel system for leaks. Close off the vent, disconnect the engine, and pressurize it over night (by mouth). Or if you want to do a more thorough check, pull the system from the plane, pressurize it, and dunk it in water to check for bubbles.
Already done that
ORIGINAL: gaRCfield
Check the balance of the plane in the air, not on the stand. The stand gets you close, all adjustments to be made by flying. Fly straight and level at 3/4 throttle, pull to 45 degrees, roll inverted and let off elevator. What happens? If you are concerned mostly with 3D, the plane should continue straight, or even gain a touch of altitude. ''Neutral'' will have a very slight decrease in altitude.
-Don't forget that balancing on the machine is without fuel, and if you're flying 10 min and landing with fuel in reserve, that's a bunch of extra weight in the nose.
Hope this helps. Good luck!
Didnt do the in air test. I did balance without fuel. I dont think the reserve fuel is that critical to balance In any case, that reserve was for when I start getting more comfortable with the setup, I had two timers one set for 10 and the other for 12 minutes. So if I do a lot of hovering, I will fly for 10 and if I do more pattern, I will fly for 12mins.
Some weeks back, I had a hard landing after the engine quit in flight and broke the LG. When I repaired, I added more ply and tristock everywhere. I also added 1" wide birch wood to the LG Block so that it would take harder landings. Consequently, the airplane has become slightly heavier. Note that I do have a FS72A. I just dont want to open it as if it doesnt have sufficient power either (which is likely), I will have another unused engine. I have already run in the 91 and it would be better to keep it operating instead of idle
Ameyam