JS615

What would be the best prop for my os 55 ax on my new f20 tiger shark?? I need speed...... And how fast do you guys think i can get this plane up to with that combo?????

bob27s

My Feedback: (19)

From what I have seen the OS 55 is not a very good rpm/speed engine. Not much tendency to unload in the air.

You have to prop it down - keep the engine below 14,000 rpm.

Id go with something like a 10x8

JS615

How about if i add a JETT muff...?????? I put one on my os91fx and it really opened her up, or it seemed to!

bob27s

My Feedback: (19)

The engine has very conservative porting. Its not likely going to become an RPM engine like the OS46FX or Thunder Tiger 46 Pro is capable of. You can add the jett-stream, the problem is you have to prop the engine to get to 15K rpm or higher to really allow it to work well, and the OS55 does not seem to like to run at that rpm.

The OS50 is another story.... that engine can scream if given a chance

JS615

So i should of gotten the os46ax insteed?

JS615

How about a st 51. i have one sitting around??

Ed_Moorman

My Feedback: (1)

There is a lot more demand for an engine that will pull a large prop for 3D or scale as opposed to a small prop on a speed plane. It seems aparent that OS is porting their new engines for the large prop market. I know the OS .55 turns a 13" prop nicely.

I have both a .55 and a .50SX and the .50 is going on my next fast plane.

bob27s

My Feedback: (19)

Probably not...... the 46AX has the same issue (As Ed noted.... big props). Although it seems to work up toward 15K rpm without much problem, and it does respond nicely to the Jett-Stream, there are better speed engines. DaveN and his local club run these for sport racing sometimes... he might be able to enlighen a bit here.

The ST51 would be worth trying - that has proven to be a pretty good engine over the years.

JS615

Well with the os55ax and a 10x8 prop what kind of speed are we talking about????

bob27s

My Feedback: (19)

idunno - never flew the combination. Not sure anyone has tried yet.

WJM

I had the 46 AX on my DD and was not very pleased with the speed. Like Bob said it just did not want to unload in the air, although it was great on my Twist with a 11x5. I am in the process of looking for another engine but do not have the budget for the 60LX, does anyone have any suggestions?

Thanks, Bill

Razor-RCU

My Feedback: (50)

The OS-46FX turns up nicely... The 50SX (I've had 2) are GREAT engines and with a simple Tower muffler become quite speedy- I would sell it and get a Webra-50GT

Cyclic Hardover

My Feedback: (3)

It isn't going to matter much. You have Jett or the others. 46ax are good engines and great for serious speed in certain planes. F-20 isn't one of them

150flyer

I'm using an 11 x 6 APC with an Ultra Thrust Muffler on my .55 AX. It's reasonably fast and the vertical is unbelievable. The picture shows the engine with a Master Airscrew 11 x 6, but after using many different combinations, the APC 11 x 6 is the best.

KC36330

I've seen the 55ax w/ APC 10x8 on a Patriot 40 a few weekends back and i wasn't impressed at all (took allot of runway to get airborne), my Patriot YS45 w/ APC 10.5x6 and Jett Stream out performed it by a mile, hands down. for all out speed i don't think you'll find a good prop for the 55ax, something cheap that would get you there would be the Thunder Tiger 46 pro w/ 10x7 or a 50sx if you can find one.

kc

Cyclic Hardover

My Feedback: (3)

I agree with that, I have seen many fly at the same time with a YS 45 with an Ultra Thrust muffler and Jett 50 and they seem to be equal.

WJM

Went to the LHS and they had a 50sx. Which tower muffler do you use, they have one for the 46 and the 61-75? I would assume the 46 but just in case.

KC36330

the 50SX has the same bolt spacing as the 46, not the 61/75.

kc