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YS 170 prop

Old 12-29-2007, 04:44 AM
  #1  
engqvist
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Default YS 170 prop

Hi Troy

Maybe this issue is already covered in this forum but I didn´t find it. What´s the experience so far regarding prop choice for the YS 170? I´m flying with a Zeque, so I need some brake assistance in the downlines.

Best Regards

Alf Engqvist
Old 12-29-2007, 12:07 PM
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Troy Newman
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Default RE: YS 170 prop

Since the Zeque is quite light, there are many choices. The APC 18.1-10 is a good one, also the 18.1-10W. These both will be too loud if let run full out, but dial the rpm back to about 7800rpm with this prop and the pull is excellent and the noise meets the rules. Braking is also excellent with these props.

There are a couple ways to restrict the rpm. First you can simply setup the engine for full power. Check the rpms and use the End Point adjustments or travel adjust of your radio to close the throttle back to the wanted rpm. Next you can use a Velocity stack like Central Hobbies sells. This will restrict the carb opening hole just a little and will make the intake noise less, as well as lowering the torque curve in the throttle band. This is what I do on my Astral XXc. It too is a very light Oxai plane. The 170 on this type of restriction is a beast and super quiet. Then I will dial the rpms needed in with the end point adjustment. This works very well as I can go fly at many competitions at different locations, just run the engine up to full power re-set the rpm per the Tach to the new conditions using the Travel adjustment and the engine performs very similar to the way it did at home.

The good number is about 7800 on the 18.1-10 props. These numbers are right on the FAI limits for noise.

Another options but you will likely have to reduce its rpm also is the 15.5-12 (4) Blade prop. The 160 and 170 are really the first engines we have that can actually turn this prop well. Since diameter is less the noise is not an issue. The 170 will likely be close to the noise limit on this prop because of its extra power. I know that running the velocity stack and 30% heli on the 15.5-12 4 blade will make noise but running it wide open will be just above the limit.

Hope this helps.


Troy Newman
Team YS
Old 12-29-2007, 12:45 PM
  #3  
engqvist
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Default RE: YS 170 prop

Troy

Thank you for your reply and advice. I try it as soon as the awful Swedish winter weather we have for the moment is getting better.

Happy New Year.

Alf

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