ownthesky2010
Active Member
- Joined
- Aug 22, 2014
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Hi everyone
I have started on the twin cylinder model of the sidevalve single I built in this thread.
http://www.homemodelenginemachinist.com/showthread.php?t=23909
The basic idea is a single throw twin cylinder with the same pistons, valves, cylinders etc as the single.
Displacement is around 22cc
After a lot of thought I have decided to stick to bronze big end bearings and abandoned my experiments with ball and roller bearings. There just isn't enough space down there.
I also tried a fork and blade arrangement but decided against it in favour of simpler identical offset rods.
In the end I managed to get 9800rpm from the single with an 11x6 propeller which equates to about 0.6hp with absolutely instant throttle response. Quite respectable for a sidevalve I think.
Hopefully the twin will have enough power to fly a plane.
I am hoping for some ideas about crankcase scavenging. With the single throw twin there is no change in crankcase volume so I think I will need to come up with a way to vent corrosive combustion gasses.
Saito approached this by installing a compressor in their single throw twins to vent the crankcase. I am considering a simple impeller in the backplate but wondering if I could get away with a nipple on the air intake of the carb.
Any thoughts on this.
Here are a few pics of the progress.
I have started on the twin cylinder model of the sidevalve single I built in this thread.
http://www.homemodelenginemachinist.com/showthread.php?t=23909
The basic idea is a single throw twin cylinder with the same pistons, valves, cylinders etc as the single.
Displacement is around 22cc
After a lot of thought I have decided to stick to bronze big end bearings and abandoned my experiments with ball and roller bearings. There just isn't enough space down there.
I also tried a fork and blade arrangement but decided against it in favour of simpler identical offset rods.
In the end I managed to get 9800rpm from the single with an 11x6 propeller which equates to about 0.6hp with absolutely instant throttle response. Quite respectable for a sidevalve I think.
Hopefully the twin will have enough power to fly a plane.
I am hoping for some ideas about crankcase scavenging. With the single throw twin there is no change in crankcase volume so I think I will need to come up with a way to vent corrosive combustion gasses.
Saito approached this by installing a compressor in their single throw twins to vent the crankcase. I am considering a simple impeller in the backplate but wondering if I could get away with a nipple on the air intake of the carb.
Any thoughts on this.
Here are a few pics of the progress.
