Prop size with the .46LA
 

Ok, I don't know if my hobby shop owner misguided me or I made a mistake and picked up to wrong prop size.... I purchased two 10x7 propeller, I'm reading everywhere that I should get a 11x6 or 11x7 with that size engine.

What are the implications if I use a 10x7? Less torque, higher rpm? Can I still use those prop, or should I really buy a 11x7?

Regards,

RE: Prop size with h.46LA
 

I think you could use that. I use a 10 by 6 on my 40 la. should be more speed at idle this way though

RE: Prop size with h.46LA
 

If it's a .46 LA, an 11-6 is too much prop & an 11-7 will positively kill its performance. Both a 10-6 & 10-7 work well with that motor & an 11-4 or 11-5 will also do the trick.

RE: Prop size with h.46LA
 

Throw an 11-5 on the front for good all around performance. [8D]

RE: Prop size with h.46LA
 

I think you'll be unhappy with an 11 X 7 on the 46 LA engine, IF you're flying a trainer.

An 11 X 7 is a fairly high pitched prop (the 7 is pitch), and will result in higher top speed, but lousy take off performance and pull while climbing. An 11 X 5 would be a better choice.

Now, if you're flying a smaller, faster sport type plane with little drag, then the 11 X 7 might be a good choice.

Good luck,
Dennis-

RE: Prop size with h.46LA
 

depending on the plane a 10x6 or an 11x5 should be good props

RE: Prop size with h.46LA
 

I've monkey'd around with props for my OS 46LA and found my favorite to be a 10x7. It was a bit of a dog with an 11x6, and as the other's have said, no on the 11x7.
The 46LA isn't your typical 46 size engine. They have their place, and are great engines, but are short on power, and are more comparable to most 40 size engines.

RE: Prop size with h.46LA
 

Ok that explains why he suggested a 10x7.

Thanks for all the info guys!

RE: Prop size with h.46LA
 

11x6 is the correct size for this engine with a trainer,the 10x6 will be too fast if your a new pilot!!.my la 46 has a graupner 11x6 and has plenty of power!!.a smaller prop will be much faster ,more rpm so get a 11x6 for your trainer.did you try the setytings a gave you for the engine?,let me know how it goes and good luck.also a trainer only needs the power of a good 25 to fly so the 46 la is fine!!.just get a 11x6 prop on it!!!.

RE: Prop size with h.46LA
 

I just got my plane yesterday, I didn't break in the engine yet!

I'll post a review on how everything went.

RE: Prop size with h.46LA
 

An 11-6 is NOT the correct size prop for that engine. It would be just fine for a .46 FX or AX, but it is like throwing an anchor over the side with the LA. If an 11" prop is needed, it can turn an 11-5 acceptably, but not with excessive enthusiasm. It spins an 11-4 with authority.

Martno1fan, the plane will certainly fly with an 11-6, but the engine is dragged well below its torque peak by the prop. You may think that it has plenty of power with the 11-6, but there is noticeably more to be had with a flatter pitch prop.

RE: Prop size with h.46LA
 

Hi!
An 11x6 APC is perfect propeller for the OS LA .40 and .46 engines!
I have recommended (and used myself) this prop size for years now for all newcommers in my club.
10x6 is to small for these engines as these engines are made to rew low!
11x7 is a little to large.
10x7 might work if its in a low winged sport airplane but a 11x6 APC is perfect in a highwinged trainer aircraft. Like in a Kyosho Calmato.

Regards!
Jan K
Sweden

RE: Prop size with h.46LA
 

Wow, so many different opinions... [X(]

well, since I bought two 10x7 already I will give it a try, but just in case, I'll also buy a 11x6 prop and give it a try when the 10x7 breaks. :D

RE: Prop size with h.46LA
 

i think if you read what i said i said its the perfect size prop for a trainer!!!!11x6 that is.but like someone allready said these engines are built to rev LOW so thats perfect for a TRAINER.by all means try a10x5 or 6 for more revs just dont expect the engine to last long!!!.

RE: Prop size with h.46LA
 

On second thought, I'll try the 11x6, It's more important for me to fly slower!

RE: Prop size with h.46LA
 

Wow indeed.

I've messed with these RC things for 50 years now & I've owned & tested more engines than most of you guys have had years to live. An 11-6 is absolutely not the correct prop for either an OS .46 LA, or particularly an OS 40 LA. On 10% nitro & @ 400' asl, the 40 LA can't turn an 11-6 above ~ 10,300 - 10,400 static rpm -- the torque peak is @ 12,700 rpm & the power peak is @ 13,400 rpm (real world -- not OS advertising). The 11-6 will positively kill any acceleration & climb -- performance factors that you will need.

For a trainer aircraft, fit either the 40 or 46LA engine with an 11-4 -- the 40 will spin it @ ~ 12,000 & the 46 will get it up to a bit over 13,000, giving you essentially all of the power available from these rather weak engines. The cruising airspeed will be limited by the flat pitch prop (and the throttle -- that's what it is for), while the plane will be able to take-off & climb strongly (which I guarantee it wont do with an 11-6). Landing speed will also be significantly reduced with the 11-4 over that achieved with a high-pitch prop. At idle speed, the slipstream velocity from the 11-6 will be nearly 50% greater than that from the 11-4 & that translates directly into airspeed at idle -- which would be at landing. Additionally, when the throttle is closed in flight, the 11-4 acts as a much more effective airbrake than the 11-6, thus more rapidly slowing the airframe -- it will permit a steeper descent with the 11-4 at a safe airspeed -- which would be your landing approach.

And one more thing -- overloading the engine with an oversize prop will not only limit the output, it will cause the engine to run hotter & and wear faster than it would if correctly propped. It can cause detonation (pre-ignition), it increases the piston side load (rubbing on the sleeve), it increases the shear load on the crankpin & wrist-pin & it increases the radial thrust load on the crankshaft bushing. None of that is good for the engine. These little OS LA series engines are particularly susceptible to overload damage, as they have very thin cylinder liners. Non symetrical heating from side-load friction can cause local hot-spots on the liner --- which will eventually peel its nickel coating.

RE: Prop size with h.46LA
 

Ok, here is a new question :-)

What will be the consequences if I use a 10x7 prop like the hobby shop owner suggested? I hear ya about the 11x4 and 11-5 but what about 10x7?!?!?

Will I be able to take off and fly properly with a 10x7?? I bought 2 already and would like to use them if it doesn't mean hurting my engine or crashing my plane because I have to wrong prop!

Thanks!

RE: Prop size with h.46LA
 

oups, never mind my last post britbrat, I re-read you first reply "Both a 10-6 & 10-7 work well with that motor & an 11-4 or 11-5 will also do the trick. "


ok I'll stay with what my LHS owner and britbrat said... I'll keep the 10x7 prop on there!

Thanks everyone!

RE: Prop size with h.46LA
 

First -- I apologize to everyone for my aggressive post -- I'm sorry about that -- I got a bit revved up.

The 10-7 is a good all-around prop for the engine & it is a good fit for a wide variety of planes, trainers included, although not necessarily ideal. You will be able to take off & climb OK with that prop, & you will probably get the highest level speed with your trainer that the engine can deliver, but your model will land faster than it would with a flatter pitch prop. If landing speed is a problem, go to the flatter pitch, larger diameter prop (11-4, or 11-5).

RE: Prop size with h.46LA
 

or perhaps an 11x6?,:D all i can say 11x6 is ok for my trainer and who wants faster landings or verticle take offs when your learning;)

RE: Prop size with h.46LA
 

OK :D:D:D:D I give up

RE: Prop size with h.46LA
 

i bow to youre superior knowledge mate :D or not haha ,only joking i just felt seeing as this was for his 1st plane the 11x6 was a good choice.after all he will have his hands full as it is learning to fly so speed isnt his main concern!!.but lifes all about opinions isnt it?.

RE: Prop size with h.46LA
 

Thank goodness that none of us have strong opinions :eek::D