Mud Duck Aviation Forums

Can you suggest an appropriate size of gas engine (in cc's) for a MudDuck MkII?  I would like to build one over the winter for airshow work next summer; candy drops, etc.  I would prefer a gas engine because I've been able to get better smoke using them as opposed to Glow.  I'm gussing something between 20cc and 30cc.  Any advice?  Thanks- Gus Dundon

Hi Gus,

  You can fly the MkII on any gas engine from 17cc's up to over 50cc's.  What should dictate your decision is, first, application of the MkII; in your case you want to make it a fun-fly workhorse (candy drop, banner pull, glider tug, etc.)  I would go as big as your budget allows up to 30cc-40cc.  This will allow you to have plenty of power to fight the regular drag, plus all the extra drag from towing and loaded weight (candy). 

  The airframe can handle bigger than 40cc's but there really isn't any appreciable difference in performance, the only reason I mentioned 50cc and up was because if you have a 50cc laying around and would have to buy a smaller engine, if you wanted 40cc's just use the 50cc you won't overload the plane. Just for reference, I have a customer who has re-modded his Agri-Duck several times and the all-up-weight is over 40# and he is flying it on an 80cc 4-stroke gas motor with a pull starter!  So it just goes to show you the range of use and applications you can apply to the Duck designs.

  As I mentioned initially, the MkII can fly on as little as 17cc nicely, but that would be at stock weight and may have limited climb to altitude speed.  A lot of gas powered duck builders actually use old converted weedwacker/chainsaw/blower motors in the 30cc range and love the combination.  Loping off the "chin" or "beak" of the MkII and installing a vertical firewall just behind the stock "chin" location offsets the balance well to carry a 3-5 pound engine.  The Ducks do not need a "performance" engine on them, so big heavy gas engines that lack peak power are perfectly at home on the nose of a Duck.

Greg