Gramin@aol.com wrote:
> << Peter has fitted the 912S to his Europa................ and cruises
> straight and level at a solid 150 knots. >>
Dave Watts replied:
>As you will see in the issue of the club newsletter that I am about to
>send out, Peters is no standard Europa anymore....
The difference would have to be mostly in reduced drag. I looked it up in S.
Hoerner's "bible" (Fluid Dynamic Drag), and cruise speed is approximately
proportional to the cube root of horsepower divided by wing area: V -> (HP/FT
2)
.33 (best attempt at ASCII presentation). Also, the data sheet I have
for the 912 ULS says it is rated for 95 HP continuous; 100 HP for 5 minutes
(is there another version of the 912S?).
Anyway, this comps to 5.65% speed increase, 95 verses 80 HP, per Hoerner.
Similarly, Don Dykins book (Understanding the Aerodynamics of Your Europa
Aircraft), presents a graph which would put the speed increase at about 7%,
and Hoerner does suggest variables which would explain the difference.
Regarding PFA's 150 knot speed limit, is this indicated (CAS really), or true
airspeed? Why the big variance with Europa's Vne?
Regards,
Fred Fillinger, A063
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