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Sensenich Pitch

K

Kevin Hull

I'm New Here
I've been happily flying my RV6 for 9 years with a 160 hp IO320 and a Colin Walker 70 By 70 wood prop. A good match.

I'm buying a new 160 Hp O320 this week and want to switch to a metal Sensenich because I quite often end up flying in rain showers. I've tentatively picked a 70CM7S16-O 79 (79 pitch).

My RV6 has gear leg fairings, old style wheel pants, and the older long cowling requiring a 4 inch prop spacer. I'm more interested in cruise performance than a short takeoff distance, and my home airport is at sea level.

I wonder if anyone has a similar set up RV6 and could indicate to me if they recommend this prop. (pitched at 79).

Thanks
 
Prop

Call Sensenich. They are very knowledgeable about the RV series and will suggest the pitch. I think I had a 79 pitch on an 0320 in my RV6 but I have converted Hartzell a couple years ago. I would have to check my logs at the airport and can get the numbers but it will be a few days. What I had worked well and I think was actually faster in cruise than the CS prop.

Dick DeCramer
RV6 N500DD
RV8 Fuselage Center section
Northfield, MN
 
Kevin Hull said:
I've been happily flying my RV6 for 9 years with a 160 hp IO320 and a Colin Walker 70 By 70 wood prop. A good match.

I'm buying a new 160 Hp O320 this week and want to switch to a metal Sensenich because I quite often end up flying in rain showers. I've tentatively picked a 70CM7S16-O 79 (79 pitch).

My RV6 has gear leg fairings, old style wheel pants, and the older long cowling requiring a 4 inch prop spacer. I'm more interested in cruise performance than a short takeoff distance, and my home airport is at sea level.

I wonder if anyone has a similar set up RV6 and could indicate to me if they recommend this prop. (pitched at 79).

Thanks
Click to expand...

79" will work fine for your plane. But you might consider changing to the pressure recovery pants and going 80". Here are details on repitching the prop on my RV-6:

http://thervjournal.com/fairings.htm#repitch

I am based at 592' MSL.
 
Kevin,

I am running an 80" pitch prop on my 160hp RV-6A, and can still turn 2630 rpm at low altitude (2000') and 2600 rpm at 8000ft. I do have pressure recovery wheel pants and the later cowl. I would be tempted to start at 80" or even 81" for a -6 if you're after cruise speed. Although initial acceleration on take off is impacted with every inch or additional pitch I can still achieve a ground run of around 1000' at max weight (500' MSL on a standard day). I used to be at 79" but had another inch added when I could over rev the prop too easily at just about any altitude.

Pete
 
Pitch

Thanks very much for the knowledgable info. I ordered a new engine today and will use your advice when I talk to Sensenich tomorrow.

It will be nice to have a brand new engine/prop. I figure both me and my plane should reach TBO about the same time!

Kevin
 
Hi All

I have only had my 6A since last Saterday. Its fitted with a 0-320 with a 79" Sensenich prop.

I seem to be able to over rev very easily at 6000 ft. I am not sure if the prop has ever been worked on. I also notice that I dont seem to get more than about 150 MPH indicated at 2600 RPM. I was hoping for a bit more to be honest.Not sure if there is anything else I should be looking at that could be slowing me down.

The plane flies nice, no heavy wing or trim propblems, just a little slower than I was expecting.

Shawn
 
Chunky said:
Hi All

I have only had my 6A since last Saterday. Its fitted with a 0-320 with a 79" Sensenich prop.

I seem to be able to over rev very easily at 6000 ft. I am not sure if the prop has ever been worked on. I also notice that I dont seem to get more than about 150 MPH indicated at 2600 RPM. I was hoping for a bit more to be honest.Not sure if there is anything else I should be looking at that could be slowing me down.

The plane flies nice, no heavy wing or trim propblems, just a little slower than I was expecting.

Shawn
Click to expand...

Congratulations on your new plane!

What is your true airspeed (altitude, temperature)?

Do you have the old-style or pressure recovery wheel pants?

All gear intersection fairings installed?

Difficult to evaluate performance without knowing the above details.
 
Hi Sam

All gear fairings fitted with New Pressure recovery wheels pants. TAS is about 150 kts. Thats the fastest I have seen, dont seem to be able to get more. I have done runs in both directions 135 one way 150 other way. Average then is about 142.

Seems very slow for a 6?

Shawn
 
Was that ground speeds?

Chunky said:
I have done runs in both directions 135 one way 150 other way. Average then is about 142. Seems very slow for a 6?
Shawn
Click to expand...
Congrats Shawn!
So that sounds like GPS ground speeds? since you slowed way down the other direction? The usual true airspeeds calculated from indicated is showing 150 Kts? If that is so you would get an average speed of 150Kts showing 165 Kts (GPS ground) down wind and 135Kts (ground) upwind.

A lot of things can slow down an RV- I have seen a fuel vent screen that probably slowed a RV-6A down by 2-3 knots. It had things not cleaned up such as the old style wheel pants, no leg fairings, not the cleanest vent and rear tail fairings etc. Best it could do was 135 Kts(152Miles Per hr). The wood prop was under pitched also.
 
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Chunky said:
Hi Sam

All gear fairings fitted with New Pressure recovery wheels pants. TAS is about 150 kts. Thats the fastest I have seen, dont seem to be able to get more. I have done runs in both directions 135 one way 150 other way. Average then is about 142.

Seems very slow for a 6?

Shawn
Click to expand...

Sounds like your TAS numbers are suspect.

Give these links on Kevin Horton's excellent site a careful read:

http://www.kilohotel.com/rv8/phplinks/index.php?&PID=49

Determining TAS is an exacting process that requires precise flying if you don't have a computer in the panel that runs the calculations for you.

I suspect your plane will be "faster" after you harvest some accurate numbers. :)

Your prop is somewhat underpitched for max speed, but it is a good compromise that yields good climb rates.
 
Sam

The numbers are from the GPS in both directions at 2600 RPM. Max climb rate is about 1000 ft/min.

Seems a bit slack for a 6.

Shawn
 
Chunky said:
Sam

The numbers are from the GPS in both directions at 2600 RPM. Max climb rate is about 1000 ft/min.

Seems a bit slack for a 6.

Shawn
Click to expand...

Please read the links I posted to see how getting accurate TAS numbers is much more involved than just flying in two directions.

Climb rate is 1000 ft/min at what weight?????? What density altitude?????? What airspeed????
 
Ok guys...

I did my first real test to see what the speed and fuel burn is on the 6A. I did about a 2.5 hour flight. I averaged out at 154 kts TAS burning 26 litres per hour (about 7 gallons per hour).

The entire flight was done at around 2400 to 2450 RPM. We are situated at 5000 ft ASL and I flew mostly at 6500 ft. Temp outside was in the 30 to 35 degrees celsius range. I had a passenger so with fuel etc we were close to 1800 pounds.

Does this sound about right?
 
Chunky said:
Ok guys...

I did my first real test to see what the speed and fuel burn is on the 6A. I did about a 2.5 hour flight. I averaged out at 154 kts TAS burning 26 litres per hour (about 7 gallons per hour).

The entire flight was done at around 2400 to 2450 RPM. We are situated at 5000 ft ASL and I flew mostly at 6500 ft. Temp outside was in the 30 to 35 degrees celsius range. I had a passenger so with fuel etc we were close to 1800 pounds.

Does this sound about right?
Click to expand...

Right on the money:

http://www.vansaircraft.com/public/rv-6per.htm

At 7 gal/hr you are at 55-65% power.

You have a fine plane. :)
 
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