Buka

hi all

i would like to ask your opinion on what is a good pattern prop for the 140 ... i am currently using a 15x12W... i havent experimented yet since i am quite new to ys and pattern so would like to hear your opinions.

thank you

mjfrederick

15x12W seems like it's a little short to me, but with it being a W it is probably OK. What kind of RPM's are you turning? As Troy points out often, the full-throttle RPMs should be the determining factor. I can't remember what the range is exactly for the 140DZ, but I think it's somewhere between 8400 and 9200. When I first started running the 140DZ I was using a 17x12. I recently dropped down to the 17x10 in order to slow my airplane down.

Troy Newman

I know many folks ran the 17-12 full blade on the 140DZ. I alwasy felt this was topo much load on the engine. I prefered the 15.5-12.5W or the 16-12. I learned from the european and japanese pilots that the smaller prop wqs better on the engine and better on the noise. A 15.5-12.5W was a really good prop on the 140DZ it was whisper quiet and pulled like stink. I say run it about 8400-8600rpm. This will make the best power. For me the 17-12 would load the engine too far down to about 8000 maybe 8200 on a really frsh strong one...this made things more critical. I ran the 17-12 regular on the 160DZ. I also know that this was the prop and setup used by CPLR for many years and a couple World champs. 160DZ on the 17-12.

Troy Newman
Team YS

RED BULL

Troy, for precision and pattern flying on my 140 sport, using 30% heli fuel, what prop would you recommend ??? The plane is still the same 9.5 - 10.0 pounds 72” Aeroworks Yak 54 that till now had been using the APC 18x6w for general fun and some 3D. Now I need something that will make the plane track a little better without gaining to much speed.

Francesco

RED BULL

P.D. the engine is very fresh and pulling really strong.

Robbidos

My Feedback: (20)

Troy is out of town till tomorrow evening. He is starting my 140 sport in a Dr Jekyll 2 with a 15-11 to break in and going to a 15-12 or 16-10 afterwards. Hope that helps.

RED BULL

Robbidos, What do you think of using a 17-8 or even a 18-8 in this particular plane ???

Troy Newman

Those props may work...You need to keep the RPM in the right range. About 8400-8800rpm is best for the 140's. Regardless of generation. The 140DZ is the direct injection engine and will be more powerful than the 140 Sport.

In a pattern application usually we tend to run 10 pitch to 12 pitch props. The models will groove better and have better energy through the manuevers. The flat pitch props like 6's and 8's are better suited to 3D type applications as they will be more stop and go....The models don't groove well on these props because as soon as you cut power the model stops like a parachute is dragging out the back...and as soon as you throttle up the model leaps. Result can be jerky throttling transitions and the flow of a sequence is tough to maintain.


In a pattern sequence the model is not stopping so there is not the need to have the wide range of speeds available and overall the 3D maneuvers get a slower speed range overall.

You will just have to play with prop sizes based on your fuel choice and you conditions...run the engines at 8400-8800 rpm and they will be happy. So larger diameters will require low pitch to maintain the load range.

Troy Newman
Team YS

RED BULL

What about trying a 17-10 on the 140s on 30% heli fuel ??? Will the engine be in the 8400-8800 rpm range ???

Francesco

Troy Newman

I can't tell you where it will be rpm wise...There are many many factors. Fuel is only one of them. Air temps, density, elevation, exhaust system, and so on. These things all add up to the rpm performance numbers. This combined with the engine itself...you know some are just stronger than others.

I will say I doubt the 17-10 std prop will hit those RPM numbers but it might...the 17-10N blade should come closer tot he numbers....But if you are high elevation above sea level or its really hot temps it will affect it.

The 16-10 is about perfect on the 140 Sport with 30% heli fuel...the 16-11 is also good but a little more load on the engine.

Troy Newman
Team YS