Lighweight opposite 2-stroke engines

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Niels

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Aug 15, 2019
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78
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.
 

Bille Floyd

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Joined
Sep 26, 2019
Messages
451
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

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Feb 19, 2012
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NJ
at low rpm this vibrated really bad....course it is not fully broke in here.....3w-200
 

Bille Floyd

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Sep 26, 2019
Messages
451
...
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

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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

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Jan 29, 2014
Messages
294
Location
Krasnoyarsk, Russia
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.
 
Last edited:

Brünner

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HBA Supporter
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Apr 12, 2020
Messages
119
Location
Beer country
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
 
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