Lighweight opposite 2-stroke engines

[erkki67]

No, I dislike due high vibration, planning make 2 and 4-cylinder V90.

Don’t the counterbalancing shaft take out those unwanted vibs?

 

[erkki67]

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.

 

[Niels]

Don’t the counterbalancing shaft take out those unwanted vibs?

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]

counterbalancing shaft take out those unwanted vibs?

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]

2cylinder engines work much better. I making at moment rotary piston (wankel). No any intent or planning make one cylinder engine bigger than 147cc.

too sad!

 

[Bille Floyd]

Don’t the counterbalancing shaft take out those unwanted vibs?

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

 

[proppastie]

at low rpm this vibrated really bad....course it is not fully broke in here.....3w-200

 

[Bille Floyd]

...
at low rpm this vibrated really bad....course it is not fully broke in here.....3w-200

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

 

[proppastie]

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]

Boxers are always vibrate on low rpm, to decrease this I use digital ignition and 2...3 degree spark switchable advance difference in cylinders

 

[jbiplane]

2 new toys will soon ready:
Liquid cooled 46hp boxer with 25kw electrical generator

and first attemp to makе air cooled paramotor wankel

 

[Vigilant1]

and first attemp to maik air cooled paramotor wankel


View attachment 107372

Two interesting projects! What is your plan for cooling the rotor--oil or charge cooling?

 

[jbiplane]

charge cooling

207сс charge cooling. Planning make 650cc one section wankel using Mazda RX8 housing and rotor with oil cooling.

 

[jbiplane]

One fanny idea. Tried in Solidworks.

 

[jbiplane]

Added frontal lid tp the case