Hi everybody,

I have built a gp venus and can't get decide which engine to use. Actually ı have mounted a ys 45. But this engine dissaopinted me or I could not solve her languge. But anyway I have decided to change the engine in terms of having no more headaches like with my ys 45. Actually it spins 11*6 apc with powermaster 20 at 11300rpm but not enough for 2300gr gp venus to go unlimited vertical.

please give me your recomendations about the engine choice!!

-should I buy a os 50 sx with mac's black muffler or,

-should ı buy a os 61 fx and have the power ı need with a 300gr more weigth.

300gms is a lot of extra weight to put on the front of the plane. As 60's go, the FX isn't that powerful either.
You might want to consider other bored out 40 sized engines instead like the Irvine 53 or the Magnum XLS52 ...

I agree with tiggerinva the sx is a helicopter engine even though it has lots of power it is way heavy for the plane. What is the wingspan on the venus, and how much does it weigh?

Put a .72 4 cycle in it and put on a show...APC 13x4 W prop

The os50sx just weighs just over a half ounce more than the 46 fx. Thats what about 13 or 14 grams?

13.8 oz for the 50
13.2 oz for the 46

The sx is not a heli motor. flyboyrc you must be thinkin of the sx-h it is a heli motor.

go with a big bore 40 like the irvine 53,magnum xls .52,or a webra 50.The problem with the .61 is the 91 weighs the same (a ton).

Of the two, 50 sx.

but go with a Saito 72 and and apc 13x7.

I had two with OS 50SX's. IMHO, the perfect choice for this plane. If I can remember correctly, I believe I used a 11-7 or 11-8 APC prop. Want to get another Venus for my OS 50SX.

Go with the OS .50 sx and put an Ultrathrust Muffler on it!

My vote is the Saito 72, but I use a 14-4 wide blade APC

Do you use that prop on a Venus?
Here is the current TH listing: [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBMZ5&P=7]Venus 40[/link] Note: It is in the wrong category.
I've got the Tracer which is a very similar design. i.e. this is more like a pattern plane and is not a 3D plane. As such, I don't think the 14x4 would be a good prop for this plane, you might also have ground clearance problems...

I think the same think with you tiggerinva.It is a wrong prop choice.Venus is not a 3d plane.I think 11*6 or 12*6 is the best options.