Mud Duck Aviation Forums

 I have a first place engine, 21cc approx 2 1/2 Pd's....also a weedeater conversion,23cc approx 3 1/2 Pd's.
 First question is, would the gas engines fit into the MKII and the Agri-duck ?
 Also, gas engines are normally mounted with the engine upside down. Would this be possible to do ?
 Thanks in advance for any info provided.

Hi David,

  Yes, many have been built with a gas engine, both conventional and converted engines.  Everyone that I have seen has mounted the engine right side up due to the simplicity of doing it that way and you would have to essentially modify the nose a bit to mount it inverted.  You can do it pretty easily since the design is very simple to begin with, but the plane is so large and there is so much space for the motor upright, it doesn't look out of place there upright.

Here are links to Doug Russels Agri-Duck with a ryobi on it:


Here are others:
http://www.mudduckaviation.com/cpg/displayimage.php?album=6&pos=0
http://www.mudduckaviation.com/cpg/displayimage.php?album=6&pos=2
http://www.mudduckaviation.com/cpg/displayimage.php?album=6&pos=3

He made a change to the engine mount and made a flat vertical firewall because his engine was already a radial mount.  If you have mounting lugs on yours for horizontal mounting like a lot of weedwackers do, you can use the existing mount design.