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Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Radial Engine, 8 cylinder

by Oldbrass May 14, 2014
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Hi Oldbrass,

thanks for this, I printed one half size for an RC model aeroplane (an Autogyro actually) and it looks pretty smart. Would you have a problem with me chopping the centre out (this would make it much lighter)??


Nice looking model.
One small nitpick, I believe radial engines always have a odd number of cylinders in a single array. You can get even numbers, but it's made my stacking two odd numbered 'slices' on top of each other.

I found one!
There was an 8 cylinder, radial! Plus, I found something on even vs off number of cylinders...
surely a radial engine has to have an odd number of cylinders to get
even firing angles? Not in this case. As Bill Todd points out: "A cam
engine fires every 360 degrees, so a two, four or eight will give
180, 90 or 45 degrees between firings and can be evenly spaced in a
I'd love to say that I planned it that way... but... :)

Thanks Gav!
And I do believe you are generally correct. I have seen 6 cylinder radials before, but I have not actually seen any 8's that physically exist (and I'd love to know the reason behind that). This one has 8 only because when I built it I had not yet figured out the command to duplicate on a set axis in 123D Design. By the time I did, I had already manually placed them all by simply rotating the duplicates 45º. I'm not done with this design yet, so I may very well fix that and make it a 7... or maybe a double row, even! I'm enjoying this way too much to stop now.