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

 

[mm4440]

Liquid cooled 46hp boxer with 25kw electrical generator

Interested in a version for self launch sailplane. Want to know more.
Murry

 

[jbiplane]

version for self launch sailplane

jbiplane@gmail.com

 

[TLAR]

Will you have a distributor for your engines in the USA?
When?

 

[jbiplane]

Will you have a distributor for your engines in the USA

I have few regular EU customer who testing testing and testing and probably will resell with technical support in EU. For USA some peoples asked for, but I need somebody who could make some minor repairing, organyze parts and engines stock. This year I should complete infinite R&D and make commercial products in a box. I will speak soon in details with persons who already asked me about distribution.

 

[Brünner]

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.

Can someone please explain what are those "second order forces" in terms understandable to a dolt like myself?

Many thanks,
Brünner