Thanks for the better calculation. I haven't any useful books on the
subject at hand
so approximated. I'm glad the theoretical numbers are about half of my hen
scratchings,
'cause Jim and Augustene spent as much or more attention on airframe
cleanliness than
Kim did. Several folks have mentioned that the Whirlwind prop is better
pitched for
the 914 and for high speed cruise. Others have suggested a optimized blade
for the
Airmaster could be in the offing and offer better power transfer.
But does anyone have any thoughts on Jim's question about diminishing
returns for the
914 vs. 912 in the Europa airframe?
Shaun
----- Original Message -----
From: "Fred Fillinger" <fillinger@ameritech.net>
Subject: Re: speed kits
> Shaun, to make comparisons more complicated yet, Kim Prout's Europa,
> at time of CAFE test, had the aftermarket piston mod (alleged 92HP,
> but who knows). He found more performance improvement in the 2-blade
> constant-speed Whirlwind -- in general true for 2-blade in cruise,
> better having controllable pitch.
>
> At 100% power, I compute approx. 8% greater velocity for 914 vs 912.
> "Approx" because Hoerner says it most closely relates to only wing
> efficiency, which varies, not total drag of A/C. I don't understand
> that, but he should know. :-) A Europa could thus come out a bit
> higher.
>
> Regards,
> Fred F.
>
> > I reread the CAFE report on Kim Prout's N111EU, as it's often offered up
as
> > the gold standard
> > in performance.
> > ALT=8K RPM=5200 PROP RPM=2286 WEIGHT=1293 LBS CAS=136.1 MPH TAS=153.6
> > MPH/133.5 KTS
> > ALT=8K RPM=5400 PROP RPM=2374 WEIGHT=1294 LBS CAS=138.0 MPH TAS=155.7
> > MPH/135.4 KTS
> > ALT=8K RPM=5500 PROP RPM=2416 WEIGHT=1294 LBS CAS=138.7 MPH TAS=156.5
> > MPH/136 KTS
> >
> > ALT=1K RPM=5800* PROP RPM=2548 WEIGHT=1270 LBS CAS=169.1 MPH TAS=171.9
> > MPH/149.2 KTS
> > *not stated
> >
> > Jim and Augustene report 142kts (is that CAS or TAS?) /6000ft/ 5300 RPM.
> > That's full cruise RPM for the 914, I think.
> > 5500 is full cruise RPM for the 912 Kim uses.
> > HP at altitude: 914: 100HP (turbo!) 912: 78*0.8=63 1.58 speed
should
> > be proportional to cube? root of power.
> > All other things equal, the 914 should be about 15% faster than the 912.
> > I will assume that Jim is reporting CAS and use a 1.14 CAS/TAS factor
( off
> > somewhat ) to get TAS=162.5 MPH.
> > Jim is about 4% faster than Kim.
> > Kim must be using aeronautical drag grease.
> >
> > Shaun
>
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