Sensenich Metal Prop

Just got off the phone with Ed (Zerka?) at Sensenich Props and have some news to pass on to you all. Ed said that he would appreciate it if I would.
1. Lead time on metal props is approximately 1 week. Plenty in stock.
2. CM type prop metal prop restriction of 2600rpm max is for LEVEL FLIGHT. Climb out of 2700rpm full power on the 0-320 160HP engines is accecptable.
In fact he stated that you should only climb at FULL power, not restrict full power by RPM with the metal props and do not reset throttle linkage to restrict engine to 2600rpm max.
3. Effective 1 March 2008 Sensenich will have a PRICE INCREASE. He suggested that the price increase would be somewhere in the neighborhood of $50-$60. So if you order prior to 1 March you will essentially get free shipping vs after 1 March.
Mike H 9A/8A

Confusion

I think there may be a little confusion here. The statement: "....2. CM type prop metal prop restriction of 2600rpm max is for LEVEL FLIGHT. Climb out of 2700rpm full power on the 0-320 160HP engines is acceptable.
In fact he stated that you should only climb at FULL power, not restrict full power by RPM with the metal props and do not reset throttle linkage to restrict engine to 2600rpm max......" doesn't make a lot of sense.

The CM propellers for RV's are all designed and manufactured to be cruise propellers. The obvious reason for this being the manufacturer's 2600 rpm operating limitation. The result of this design operating limitation is that the selected pitch of the propeller must be made high enough that at full throttle level cruise flight the rpm should approximate 2600. The only way to get to 2700 would be if you dive the airplane while leaving the throttle wide open.

You simply cannot achieve 2700 in climb with the CM propeller. More realistically the climb rpm might be 2000-2300 depending of course on aircraft climb pitch angle and your original propeller pitch selection.

Full Power Level Flight in an RV8 w/ IO-360

I know we are talking about O-320's but just as a point of reference, in level flight an IO-360 in an RV8 can exceed the 2700 RPM limitation on the Sensenich CM prop. I didn't find this out intentionally. While testing to red line TAS (199KTS) in level flight at 6500 feet I noticed my RPMs were at 2800.

Luis Luciani
RV8 N188LC - Phase 1

mike109g6 said:

Just got off the phone with Ed (Zerka?) at Sensenich Props and have some news to pass on to you all. Ed said that he would appreciate it if I would.
1. Lead time on metal props is approximately 1 week. Plenty in stock.
2. CM type prop metal prop restriction of 2600rpm max is for LEVEL FLIGHT. Climb out of 2700rpm full power on the 0-320 160HP engines is accecptable.
In fact he stated that you should only climb at FULL power, not restrict full power by RPM with the metal props and do not reset throttle linkage to restrict engine to 2600rpm max.

Click to expand...

Huh???????

The only way to get 2700rpm with the CM prop in climb would be to pitch the prop for ~3000 rpm full throttle in level flight. (Maybe it depends on the definition of "climb")

It would make for a great climb prop but the 120kt cruise @ 2600 rpm would get a little boring.

I think something got lost in the translation....I know Ed and he really knows his props.

lluciani said:

I know we are talking about O-320's but just as a point of reference, in level flight an IO-360 in an RV8 can exceed the 2700 RPM limitation on the Sensenich CM prop. I didn't find this out intentionally. While testing to red line TAS (199KTS) in level flight at 6500 feet I noticed my RPMs were at 2800.

Luis Luciani
RV8 N188LC - Phase 1

Click to expand...

You can have the prop repitched so it will only allow 2700 rpm at 6500', full-throttle. However, while this would result in the prop being optimized for cruise, you might not want to lose climb performance you now enjoy.