RE: OS 46AX On A Header & Pipe
The difference is huge when you hold both propellers in your hands,
maybe the photos are not that convincing although they should be.
Shortly, the blade of G-Sonic is much thiner and visibly more firm/robust etc,
looks Graupner have other materials-mix in the blade... I have been testing
those G-sonics the last two summers and here are some results, after
number of tests:
Engines: two OS.91FX just broken in, and two because preparing for a fast Twin.
Fuel: 11% Nitro, 3% Aerosave oil(synth, Fuchs), 17% Castor oil, rest methanol,
Temperature 24 deg.C, 45% hummidity. Static thurst by Pe's Calculator and
by Fish-Scale were giving very much same results (+/- 50 g). I used the
fish-scale because wandered what coefficient to place for G-sonic and it
seems that 1.2 as for ordinary APC is the right one. The RPMs are the
max-possible measured continuously within couple minutes while playing
with the needle.
1. OPEN EXHAUST:
APC 13x10 gives 10750 rpm, Static thurst = 5.7kg
G-Sonic 13x10 gives 11300 rpm. Static thurst = 6.4kg
2. RESONANCE PIPE(Macs) after being tuned for each(!) propeller:
APC 13x10 gives 11200 rpm. Static thurst = 6.2kg
G-Sonic 13x10 gives 12050 rpm. Static thurst = 7.15kg
The difference between the engines was in the range of less
than 50 rpm on the same propeller and varied while
playing with the carb needle to get to the max RPM possible.
The flight tests were done on a another, older .91FX and
the speed and climb were confirmed also by some other
guys (APC-adicted) to be very obviously in favor of G-Sonic.
It is worth to mention ALSO: the difference between APC and
G-Sonic is even more in favor of G-Sonic at bigger propellers,
like 16 and more inches diameter, the G-sonic is simply getting
much ahead. I am preparing for a test with MVVS-26cc glow for
the next summer and then I will post the tach-readings. Just for
now looking at and holding the 16x14 G-Sonic I simply cannot
see myself buying anymore APC and espeially the high prices
of APCs in Europe will make them no-no choise soon unless
somebody at APC renovates the APC design. G-sonic is clearly
new advanced design, but of course Aerodynamic specialists
know more; I just look at the RPM measurements ... on my engines.
The PROBLEM with G-sonic is that there are NOT (yet) so many
sizes (D and P) you can choose among as you can do with APC.
But I guess Graupner is professionally choosing the sizes to
deliver now and in the future.