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
----- Original Message -----
From: "Augustene Brown" <augustene@cfl.rr.com>
Subject: speed kits
> I would like to expand on the comments Shaun Simpkins made about our 914
> Mono wheel. N398JB.
>
> His memory is correct, we saw a small increase in the installation of
> the speed kit, in the range of 1 to 2 kts. In discussions with some of
> the other 914 pilots I am hearing the same thing.
>
> Some of the 912 operators that I have talked to have indicated that
> their increase was in range of 4 to 5 kts. I am not an engineer so I
> have a question?
>
> Could the difference be that the 914 engines are pulling the airframe
> about as fast as the drag will allow in cruise, and the 912
> installations are having a greater benefit from the speed kits
> installation due to their lower cruise speeds.
>
> Our mono wheel has the 914 coupled with the Airmaster prop. My figures
> were arrived by using 5300 RPM, 33" MP, Indicated airspeed was 142 kts
> at 6000 ft. here in Florida after installation of the speed mod..
>
> Jim Brown
> A094
>
>
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