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Nitro Engines O.S. .46 FX and Magnum .91

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Nitro Engines O.S. .46 FX and Magnum .91

Old 05-26-2015, 08:12 AM
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EuroPilot82
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Default Nitro Engines O.S. .46 FX and Magnum .91

I have an O.S. .46 fx 2 stroke and a Magnum .91 4 stroke. I am wondering what type of fuel to run. I have been flying them with 15%. Both engines have been broken in to the manufacture specs but I am not getting the power out of my 2 stroke that I was expecting. I am running a 11x7 prop on the .46 and a 13x6 on the 4 stroke. I have a tachometer also. I am located in Germany and there are not too many options for fuel here. Obviously everything is in German so the only thing I know is 5, 10, 15% fuel. I am assuming the percentage is nitro? Any info that may help is welcomed. Thank you in advance.
Old 05-26-2015, 08:59 AM
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macdona
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Default Os-46

Originally Posted by EuroPilot82 View Post
I have an O.S. .46 fx 2 stroke and a Magnum .91 4 stroke. I am wondering what type of fuel to run. I have been flying them with 15%. Both engines have been broken in to the manufacture specs but I am not getting the power out of my 2 stroke that I was expecting. I am running a 11x7 prop on the .46 and a 13x6 on the 4 stroke. I have a tachometer also. I am located in Germany and there are not too many options for fuel here. Obviously everything is in German so the only thing I know is 5, 10, 15% fuel. I am assuming the percentage is nitro? Any info that may help is welcomed. Thank you in advance.
I use 15% nitro in all my engines. The 46 fx is a good engine, but you have a little to much prop on it. For racing I use a 9x7 and for sport I use a 10x7.
Old 05-26-2015, 10:17 AM
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EuroPilot82
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Thank you macdona...I am running 15% in it right now and it has some tan oil coming out of the muffler after I fly it. I am guess from reading online that this is normal. I will look for more prop sizes here. I was surprised that my Great Planes Escapade took a while to take off compared to my Extra 300. I am use to electric which take 6 feet or less to get airborne. Once again thanks for the help!
Old 05-26-2015, 01:16 PM
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The 15% is fine, I use nothing but 15% nitro in all my glow engines. Prop testing is a must and to just give you a size would be wrong. I like a slower plane with a lot of thrust so I would try an 11X4 and an 11X6. You forgot to mention the plane and weight and those two factors will mean a lot. The little .46FX is a small power house but it isn't going to drag around a 60 size plane with a lot of authority.
Old 05-27-2015, 04:47 AM
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EuroPilot82
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I have the OS .46 on the Great Planes Escapade MX and I am not sure about the weight. It isn't heavy compared to my Extra 300SP but the Extra 300SP has a .91 on it. The escapade in the air flies very well and handles great. The motor seems a bit off to me for some reason. When I go inverted the plane wants to cut out or if I do a knife edge the engine wants to cut out. I bought the OS .46 off of a German guy in my club and it came with a long exhaust pipe with 2 ports. I am not sure what the 2 ports are for. I know that one is for the pressurizing the fuel tank. I connected the pressure tank to the exhaust like a normal nitro is suppose to be and the other port I connected the refueling line. I might play with it a bit tomorrow and see what I can find out. I am trying to figure out if it is a connection problem with fuel lines or if it is a fuel tank problem. Thanks for the replies!
Old 05-27-2015, 07:25 AM
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You ran muffler pressure to the refueling line? That can't be helpful. The second tap might have been for smoke.

FWIW, the .46 fx is ported for speed. You have to let it unwind to get the power out of it that it is made to give you. A 10x7 or 10x6 will let it rev up more. Just be sure to richen it enough on the ground to allow it to unload in the air. The ST G90 is the opposite; it's a torque engine. I ran a 12x8 on mine when I had it on an Ugly Stick which it ran well with. You won't get the screaming speeds for the .90 that you can from the .46, so you have to prop it to take advantage of that torque.
Old 05-27-2015, 10:56 AM
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Hi!
I run 5% nitro in all my engines but of course you can use 15% as both engines will be some what easier to set and deliver slightly more rpm.
As for propellers the OS FX .46 and Magnum .91 will spinn many prop seizes all depending on what plane you use them in.
At sea level , flying a Q-500 pylon racer a 9x7 APC or RAM or Graupner G-Sonic is the prop of choice.
For a slow flying aerobatic airplane like a Extra 300, 330, Cap21 or anything like those a 11x6 is more suitable, providid you choose the above brands.

The Magnum .91 four stroke is more at home with either a 13x8 or a 14x6 for Extra 300 type of aerobatic planes.. A 13x6 is to small for that engine
Old 06-04-2015, 12:47 PM
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For a .46 2 stroke I use 10x7 or 11x5 or 11x6. (Bushing .46 would use a little less)
11x7 used to be considered a prop for .60 size engines. Over-propping the .46 will lessen it's power by getting it out of it's peak torque (not necessarily peak RPM) band.

I have a Magnum .91 RFS too. I get about 9700 (richened) RPM on a 14x6 APC - about perfect for that engine - using 15% nitro Omega fuel.

A tach is useful for getting data, but isn't really necessary for a 2 stroke.

Let us know what happens.

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