my pt-40 has a os 40 la motor,im currently running a 11x6 wood prop,i have ran a gallon of 10% fuel thru it,this motor is actually okay but im looking for more air speed at least for takeoff,im thinking of just getting a 46 for it. any suggestions to get more out of this engine with props,any suggestions before i get another motor to help this one out? thanks

I don't have a 40 LA, but 11x6 is at the top of the recommended prop size. If you go to a smaller prop diameter, such as a 10x6, the engine will be able to turn higher RPMs, which can translate into higher speed. Staying at the same diameter, but dropping to a lower pitch, such as an 11x5, will also let the engine turn at higher RPMs, and should give you shorter takeoff distances. In short, buy a few props such as 10x6, 10x7, 10.5x6, and 11x5, and see which is best for what you want.

Something to remember is the .40 LA is a good, but basic, engine. Don't expect it to give you unlimited vertical. If the props don't provide the performance boost you want, there may be nothing you can do other than upgrading to a more powerful engine. However, there's alot to be said for an engine that's not overpowered. Being forced to fly the plane on the wing, instead of on the prop, can actually improve your takeoff and flying skills.

The previous advice is good. I run a ThunderTiger 46 Pro on my LT40 with excellent results with an 11X6 prop. The 10X6 permitted the engine to turn more rpm but with the 46 the 11 inch prop is best. I would change out the wood prop for a plastic Master Prop for better balance etc. I see the LT40 running both the LA40 and several makes of 46 engines with excellent results. You might consider the 10 inch prop as the best for the LA40.

Hud

Something that may be helpful to you with a trip to the bookstore... the May issue of Fly RC has an article "Learn to choose the right propeller" that explains how changes in diameter and pitch effect performance. Its in the electrics section but it gives a lot of information.

Cheers,
Graham

I'd suggest goin Pipers way and drop to a 10 X 6 or even a 10 X 5. I never liked 11's on a 40 especially an LA. ENJOY !!! RED

thanks guys ill give the 10x6 and the 10x5 a try,thats what i thought but i didnt want to hurt the motor

An 11-6 is the just about the far side of too much for that engine -- you have had good advice -- use a 10-6.

theo,

The above advice is good. Just throwing in my experience.

Most of what I do is training. Have tried all props on several engines and many planes. For the .40 LA on the LT40, I have been most happy with the APC 11 X 4.

Reasons: many are interrelated.

1. Quick response to throttle input.
2. More thrust to take off sooner and get out of trouble faster
3. Slower landing speed
4. ability to stand still on smooth surface at idle
5. the LT40 is a high-drag, slow flying airplane. Thrust is what is needed, not speed.

Now, if you put the LA on a quickee, you would probably use a 9 X 6 prop to go fast and burn holes in the sky.

Perhaps opinion, but based on experience.

Just tried to attach picture of my LT40, but my firewall, or something, prevents it. And I'm a retired computer guru. (shoemaker's kid syndrome)

Ken, AMA 19352

theo,

Sorry, you said pt40, not LT40. Not so much drag, but I still believe you will get better response from the APC 11 X 4.

My bad.

Ken, AMA 19352

mr foamy thanks for the input ill try one of those as well. im not lookin to burn holes in the sky or anything like that,just better performance,mostly on takeoffs

i brought a phoenix su31 46.i will say its a nice plane. i put on a 46 evo with a 10x6 prop. my question is that i'm going to put on a 11x5 prop will there be any surprizes.i'm looking for a shorter takeoff and slow landing and i'm thinking about put on flapron to help it slow down.thank for your input.

p.s as anybody add flapron to this plane and what happen

A 10x6 on an OS40 LA will not hurt it. I got into the sport back in Jr. High with my Dad. We both learned on a superstar select (os 40 LA). We've always ran that engine with a 10x6, and its performed great. Infact it still runs fairly well, and I just finished my freshman year at Texas A&M. Now givin we don't fly every single weekend, but that engine has survived everything. From crashes, a event our club used to have called junk yard wars (yes, like the old TV show), and general flight. The key thing is to make sure that you run them a little rich. In fact, I believe a 10x6 is what they recommend.

Forgot to say, if you want a new engine, I would look at a 46 size Ball bearing motor. I personally like the Tower 46. It gives the profile in my avatar unlimited vertical. Plus it gives a trainer a whole bunch of kick.

APC's are nice props, but IMHO for smaller engines like the 40la they are too stiff (and they break more easily ) I would suggest you try a master airscrew SCIMITAR series prop its not the squared prop ,it looks like an APC but without the stiffness and bigger hub (which means no changes in your spinner)

How does a plastic prop give better balance?
thats a new one.

I believe they are not plastic they are fiberglass/nylon resins or something like that. The only way I can see that they could be better balance is if (big if) the prop touches ground and some splinters fly off... now usually with wooden props such happenstance results in a broken prop which has to be changed.

Hi!
A plastic prop doesn't give any better "balance" than anyother prop, wood or glassfiber/Carbon...what it makes is better fly wheel effect.

For a high winged trainer flying at sea level it is my personal experience from many years flying and training people that a 11x5 or 11x6 APC is the best size/prop for that engine and plane and not a 10x6...and definitely stay away from black MA props those are the worst props there is.


Regards!
Jan K
Sweden