erkki67
Well-Known Member
Don’t the counterbalancing shaft take out those unwanted vibs?
Lighweight opposite 2-stroke engines
- Thread starter jbiplane
- Start date
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erkki67
Well-Known Member
Polini shows it with the Thor 250 and Arctic Cat with their 397cc single cylinder. The later unfortunately not adapted for aircraft reduction drive installation.
No not completely.
A single cylinder with a counter-rotating shaft still has a lot of second order up and down forces.
For each crankshaft revolution you get two complete cycles and they are not insignificant.
On an opposite they cancel out.
jbiplane
Well-Known Member
2cylinder engines work much better. I making at moment rotary piston (wankel). No any intent or planning make one cylinder engine bigger than 147cc.
erkki67
Well-Known Member
too sad!
Bille Floyd
Well-Known Member
- Joined
- Sep 26, 2019
- Messages
- 380
When i go to Bennett RC field, in Las Vegas ; i can tell without
looking inside the engine compartment, if it is a twin or single cylinder
by simply looking at the wing tips, when the engine is revved-Up.
The single will shake the air-frame a, (Lot) more, than a twin of
similar size . Every engine,, over 100cc, that Desert aircraft
builds, for the RC industry , is a twin or 4-cylinder ; maybe there is
a reason , for that ?
Bille
Bille Floyd
Well-Known Member
- Joined
- Sep 26, 2019
- Messages
- 380
Almost like the prop was out of balance ? When ya increased rpm
at one point in went through a really bad vibe ; then got better.
Bille
perhaps yes prop issues....it was lots smoother at + 2000 rpm the bad vibration was at 1000 or less...this is the first engine I ever had where both cylinders fired at the same time, they were both at TDC at the same time. With all its flaws it still is an amazing little engine.
jbiplane
Well-Known Member
Boxers are always vibrate on low rpm, to decrease this I use digital ignition and 2...3 degree spark switchable advance difference in cylinders
