I appreciate your comments. I definitely realized this while learning this plane. While sport flying, I never noticed the 2 stroke time lag to wind up to power. I've gotten used to the little electric 3D foam plane and instant power when needed. I am considering this a great learning experience in engine work and flying. When I move to a "real" 3D plane, I will most probably use a 4 stroke. Granted, I'm not used to the plane yet, but this SPAD is not nearly as much fun as the videos and others' comments made it seem. It just takes too much work to keep the sheet of plastic pointing the engine in the right direction. I won't even attempt to call it flying.
ORIGINAL: NM2K
ORIGINAL: wildlifeguy
Well.... I never start a sentence with well, but it works here. Anyone want to buy a used GMS 47? Just joking. I greatly appreciate all the comments, but I've all but given up on this engine. I hate to admit defeat on it; it served me well when I bought it while on a limited budget in grad school. I really can't tell what could have changed. It shouldn't have enough time to be worn out.? Yesterday afternoon I spent over 45 minutes and probably over a quart of fuel playing with that engine. I think there is either an air leak, or it needs a hotter glow plug. The day before, it ran great when level, so I thought it would be some simple LSN adjustment. When I started it, it began surging constantly and would hardly advance past half throttle unless the glow starter was attached; even after warmed up. I played with the LSN for about half an hour and finally got it running good while level. Then I had the same issues when pointed up. The high end would lean quite a bit and when slowed to half throttle, it would die as if too lean. I continued to play with the LSN and became more frustrated. By now, the low voltage alarm on my transmitter was beeping away annoyingly making things worse. I then pulled the engine and replaced it with the os 46fx I have on my extra. As a side note, I bought this engine from an RCU member a couple of months ago as ''NIB'' and fought the mid range on it for a few days and realized it was just very picky about the LSN; could not take even slightly rich setting. It started immediately. About 5 seconds to adjust the HSN a little rich and pointed to the sky. It leaned to approx peak with no sagging and stayed that way no matter how long I held it up, and excellent response throughout the throttle range. I slowed it to a smooth, slow, reliable idle and literally threw the plane into the air. I flew three short flights with excellent engine performance at any attitude. Being new at glow powered 3D, I found that with the 46. the 12x4 APC prop has much better throttle response and instant torque than the MS 11x6. Let the chinese engine bashing begin, I might even join in. I had almost forgotten how nice it is to start an engine and fly without worry.
What you are describing is perfectly normal behavior for a glow two-stroke engine. Sorry.
The lack of hesitation during throttle up is the number one reason for folks using mostly four-stroke glow engines over two-stroke glow engines.
Have you ever watched someone using a two-stroke gas engine while hovering and noticed how their throttle thumb doesn't stop moving? The engine is constantly being revved up and down. Same thing. Two-stroke engines are poor candidates for 3D flying. Four-strokes aren't perfect, but they are the closest thing we have to perfect except for electric power.
The GMS .47 was designed to be flown mostly at WOT. In that flight regime, it serves its purpose well.
Ed Cregger