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Propeller Dynamics

Essential reading for model aircraft contest fliers. This is the only book on the market explaining propeller theory in non-mathematical terms. A rattling good read, I know, I wrote it.



Courtesy of David Zwolak, October 2005

ENYA continues its tradition of high quality model airplane engines in the current Super Sport (SS) series.  These initially came out in R/C versions; but many in the range can now be obtained as control-line fitted with a venturi and needle valve assembly.  I have had very good success with the
ENYA 40SS flying stunt and sport.

My motor is the version with plain bearing front end and iron/steel piston and liner.  In contrast, the 45 and 50SS are both ringed pistons.  Ball bearing front ends are available on all the displacements in the series.  The same crankcase is the base for the larger displacement motors so it is very sturdy for the 40SS.  This results in greater weight than other 40 size engines but gives more durability.  I think the power available from the 40SS definitely compensates for the greater weight.  So, I do not view the weight as a major disadvantage.  My motor started as an R/C version converted with ENYA parts available from the manufacturer.  You can either go this route or start directly with the C/L model (internal parts are the same).

A stock venturi of 0.277" inside diameter is fitted.  This can be either ENYA part number S5021 as I used or a custom venturi fabricated for the motor.  The NVA is standard ENYA of approximately 0.155" diameter.  A Super Tigre type NVA will also work and is about the same diameter.  Fuel tank is a 4 oz. Sullivan Clunk set up for uniflow without muffler pressure.  I did try muffler pressure but found the motor runs nicer without it.  Also, I suggest you plan on a 5-6 oz. tank if possible as the 4 oz. is marginal for the full pattern.  The muffler is a tongue design fabricated by local source.

The 40SS has been flown with both the standard head (full squish band) and one modified to give a hemi shape to the combustion chamber.  The hemi shape was cut into a regular stock head to remove about half of the squish band.

Leave about 0.060" of the original squish band remaining.  Both heads run very well but with different styles.  The stock head with full squish band will give a constant speed run with little break through the maneuvers.  The aircraft is very manageable and there is no evidence of the dreaded schneurle wind-up.  The hemi-head will give a bit of a 4-2 break; although not the deep traditional 4-2 stunt run.  My own preference for the motor favors the hemi-head providing the slight break.  But, your style may differ.  I suggest you start with the stock head and go from there.  The stock head with the full squish band certainly is acceptable "as is".

Fuel is 5% Nitro with 25% oil (50/50 Castor and synthetic).  Best props to date are either the 11x4 or 11.5x4 APC.  My preference is for the latter to give the larger diameter resulting in better line tension and acceleration.
After working through the variables to get this engine set up it has easily become my favorite.  The run characteristics are excellent.  The power is quite sufficient to fly a 600 square inch thick wing stunter through the turbulent air common at our tree lined flying site.  The ENYA quality is legendary.  You may want to consider a 40SS for your next airplane.


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