SpinnerRow

I was really wanting to run an 11x6 prop on one particular plane and I couldn't find anything that my Super Tigre G-51 on a pipe really liked that much. So I took an OS 46 AX off of a trainer I had and played with it a bit.

I tried an APC 11x6 and could only get 13,000 out of it with a pipe that was a bit too long. Maybe 13,300 if I worked with it.

I next tried a Master Airscrew S2 11x6 and this turned out to be the prop for this engine. I got it tuned to about 14,400 with a pinch to 14,600 or so. That was good enough for me. The G-51 was really close to that number as well but off by 300rpm. I really like the idle and transition of the OS though. I'll be flying it tomorrow.

Ritch's Brew 10% with 20% oil (5% castor)
Pipe is an old (from the early 80s) disk type muffled pipe.
MACS standard header
73 degrees and about 50% humidity.

Not sure if that is good or not but it should be good enough for me.

I think what I really need is an OS 55AX on a pipe running 15% fuel and using an APC 11.5x6 at about 14,500!

NikolayTT

APC propellers are getting too old, try Graupner's G-Sonic - it is a Very Efficient one !!!
http://www.der-schweighofer.at/artik...ube_sonic_10_6
and the Prices are too friendly, cheaper than APC and lot better; I am done
with APC...
Nick

SpinnerRow

Hmm, can't seem to find them locally. Is there a U.S. site that sells them?

NikolayTT

Hi,

Here

http://www.graupner.de/en/service/dealer-search.aspx

is what I can find :

Graupner Agent, Hobby Lobby International
5614 Franklin Pike Circle
Tennessee 37027 Brentwood
Tel.: +1 615 373 1444
Fax: +1 615 377 6948
Email: [email protected]
Homepage: www.hobby-lobby.com

V-EAST/ Graupner Helicopters USA
1730 Caribbean dr.
Florida 34231 Sarasota
Tel.: 941-925-9653
Email: [email protected]
Homepage: www.v-eastonline.com

-

and here is seen that it might be CHEAPER if you order from Europe: - Seems G-Sonic are Well Priced in USA:

http://www.hobby-lobby.com/elecprop_1.htm#filterValuesRequest,filter_id_76=67 |76,filter_id_147=135|147

Surely still cheaper than APC ....

I hope this help.
Nick

proptop

My Feedback: (8)

Nick...those Graupner Sonic's look surprisingly like APC's to me...just exactly what is the difference?

NikolayTT

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.

SpinnerRow

I just ordered a couple of the 11x6 G-Sonics. Once I test them, I'll post my results.

estradajae

I have tried a couple of Sonics...

They are much lighter than any other plastic props around, but not as stiff as the APC ones.

I don not like that they come with a 8mm hole! but aside from that, I like very much the Sonics!
I saw very much performance improvement on a 46fx after using an 11x6 sonic over a normal graupner prop.
My TT F75s liked the Sonic 13x7 at most!

DarZeelon

Appearances could be deceiving...

I know the specs do say the hole in the prop is drilled to 8 mm, but from measuring the dimensions in the photo, it seems to differ...

If the hole is indeed 8 mm, the hub is HUGE at ~34 mm in diameter.

For reference, I took a shot of a used Master Airscrew 11x6 Series-2 black prop, drilled to 7 mm, with my vernier caliper open to 34 mm around it.
Its hub diameter is just 24 mm.
See below.

I know an APC has a larger diameter hub, but the Graupner G-Sonic does not seem to be any larger than it is; and the APC hub measures up to only 1" (25.4 mm), according to the Tower Hobbies photo.


Can anyone verify that the actual diameter of the drilled-through hole, in the G-Sonic 11x6 is really 8 mm?

Photo analysis does not make it appear so.

NikolayTT

Hi Guys,

I do not have 11x6 but here attached are 13x10 photos; G-sonic hub is same
diameter as APC but it is thicker. Also attached are photos of 16x14 G-sonic-pro
from different angles. The shape seems not "smooth" a bit 'extravagant'....[sm=shades_smile.gif]

proptop

My Feedback: (8)

Interesting [8D]
Now that I see them from different angles, I can see the differences...thanks.
Will have to try a few...

SpinnerRow

My 11x6 G-sonic props came in Friday but I couldn't find an insert for the 8mm opening in the prop to use them. That is more than likely why they are hard to find in my area. They need to make them in 1/4" shaft so that they would work with more engines. That way if someone needed to ream it out, they could. As soon as I find an insert, I will give them a try. I put an APC 10x8 on it and retuned the pipe and really like this combo though. Good speed and decent climb. I've tried this prop before but didn't like it very well because the idle had to be upped a bit and it didn't want to slow down for a landing. I put a decent sized screw-on aluminum prop nut on it to give it more mass and that made all the difference. Idle was nice and slow and the plane slowed down decent enough for an easy landing.

Also my two G-Sonics came pretty well balanced which was nice.

SpinnerRow

Put an APC 9x10 on it today and got 15,150 peaked. I didn't retune the pipe from the 10x8 so there may be a bit left in it. I plan on flying it tomorrow.

jay1st

Hi,

I have a 46AX spinning an APC 9x6 @ 17200 RPM, just with a JETT exhaust (red one) and a thinner head shim.

So, with a little bit of porting it might gain 500 RPM.....

DarZeelon

Quote:

ORIGINAL: jay1st

So, with a little bit of porting it might gain 500 RPM.....

Jay,


Your engine has an ABN cylinder sleeve...


Actually, OS call it ABL; but it is ABN, as customary practice dictates it should be done.

There is a flash-coat of copper applied to the sleeve's brass base-metal, so the electro-less nickel coating will bond better to it.
Perhaps it does, but the bond strength is nowhere near that of chromium, in true ABC (or AAC) engines.


So, this ABL coating still relies on the surface continuity of the nickel, for its durability... And if you search this forum, you will find OS' ABL sleeves still peel occasionally.
Perhaps, the likelihood is lower than it was, when 'simple' ABN was used; but sleeve peeling is definitely not unheard of...


If your 'porting' work only entails touching up the crankcase bypasses and the crankshaft, fine.
But if it also includes porting of the ports in the sleeve, you might as well be 'jaywalking'... as you would be compromising your whole engine...[X(]


If surface continuity of the nickel is broken in a port, the sleeve will start peeling from there.

SpinnerRow

My 46AX is running to good right now but I may try my hand at porting a Super Tigre G-51 I have. Sounds kinda fun!

DarZeelon

Quote:

ORIGINAL: SpinnerRow

My 46AX is running to good right now but I may try my hand at porting a Super Tigre G-51 I have. Sounds kinda fun!

SR,


The ST has a steel sleeve... No nickel to peel.

Go right ahead!

SpinnerRow

Well, I've ported cylinder heads for race cars before so I get the concept of how this works but what areas of a small 2-stroke need the most help. Any links that can get me up to speed?

DarZeelon

SR,


Most model engine porting services keep their knowledge to themselves...

But there are enough books that discuss two-stroke gas engines. You can just 'scale them down'...

Ernie Misner

Spinner, on a 2 stroke, it's the height of the ports that determines the timing. So if you widen the ports the timing is not affected, but if you raise the height the timing is affected. A common practice on many 2 strokes is to slightly raise the exhaust port for starters. What do you think Dar?

Thanks,

Ernie

DarZeelon

You are correct, Ernie.


But as far as this engine goes (and any other ABN/ABL engine), grinding the ports in the sleeve would risk severe peeling of the nickel off it...

As I wrote, breaking the continuity of coating; together with the rather weak bond of the nickel to the brass, would make sure peeling starts from there.


Had I owned such an engine, I would not take that risk...

SpinnerRow

I won't be porting my 46AX but I might try my ringed Supertigre G-51.

DarZeelon

Quote:

ORIGINAL: SpinnerRow

I won't be porting my .46AX but I might try my ringed Supertigre G-51.

SR,


Porting the ST would be OK. No risk of peeling.

However, this thread is sort-of dedicated to the OS.46AX....

nitrometan

Well sir,we use a lot the G-Sonic around here and the figures you mentioned are more than every optimistic thinkings,especially thrust.7,15kg thrust are possible with maybe a good 3W28I CS with the best tuned pipe and 20X6 Biela propeller...

jay1st

Hi
Just to give some figures on the AX
I cleaned up the ports on the sleeve and on the crank, used a shim under the sleeve as well
With the Jett Stream exhaust, 9x6 APC 17800 rpm; 9x6N APC 18200 rpm
So it's not bad for this type of engine
I also took some readings with a degree disk ( post them tomorrow)