nose high attitude at cruise

[Steve Pierce]

The Slotted Wing Pacer was 160 hp with an 8244 prop and 26" Goodyears and cruised at 105 mph flying a 3 direction gps course. No issue with a nose up pitch.

[CamTom12]

Velocity is squared in the lift equation. So any small change in velocity will require more change from the other factors to keep lift the same.

Wing area and air density are probably pretty similar between the slotted Pacer and akflyer’s examples, so the only other thing that can change is AoA, which is wrapped up inside the lift coefficient in the equation.

[Pacer42Z]

I believe (but I am only a mechanical Engineer, not an aeronautical Engineer) when the (Tri-) Pacer was designed the angle of incidence (which is the angle of the airfoil chord line in relation to the longitudinal axis of the airframe) was set so the aircraft flies at a "normal" attitude at the designed cruise speed (100 to 105 kts?) with a wide range of trim left to balance out the load of the airplane. I believe that is the reason why some people who install 180 HP engines and try to go for speed have to use almost all of their nose down trim for the aircraft to fly hands off straight and level. If you fly your airplane at only 80 kts. cruise, you will need to fly at a much higher angle of attack to get enough lift out of the wings to stay level.
If you change the airfoil by pulling the flaps one notch, the nose should come down.

Anyhow, just my five cents of wisdom.

Juergen
Pacer N3342Z

[akflyer]

The Slotted Wing Pacer was 160 hp with an 8244 prop and 26" Goodyears and cruised at 105 mph flying a 3 direction gps course. No issue with a nose up pitch.

What RPM are you getting on take off with the 82X44. Thats normaly what they hang on the 180+ HP cubs. The paperwork with the prop when my brother bought it new says it was a 44 pitch but since I am turning 2700 on take off and can easily blow past that in cruise I think the prop was repitched to a lower pitch. Either that of I have one very healthy 160 that out turns most 180 hp. I have not yet pulled the spinner to see if the prop was re-stamped.

Thanks for the other replies guys. Will soon see how much 31" BW slow me down and hurt the climb, the 26" goodyears just aint getting it for the off airport ops I do.

[Steve Pierce]

Several years ago and I don't remember the static. I have 150 hp on my Super Cub and it will turn the 8241 past 2700 rpm as soon as I start to level off.

[akflyer]

Adding to this old thread to close out the issues. The tach was the issue. When It said I was turning 2700 on take off it was much more like 2425-2450 when checked with optical and now digital tach. At cruise when I thought I was turning 2400-2450 I was much closer to 2190 -2200. Now when I cruise at a real 2450 she flys nice and level and not that nose up wallowing crap.

[Subsonic]

Adding to this old thread to close out the issues. The tach was the issue. When It said I was turning 2700 on take off it was much more like 2425-2450 when checked with optical and now digital tach. At cruise when I thought I was turning 2400-2450 I was much closer to 2190 -2200. Now when I cruise at a real 2450 she flys nice and level and not that nose up wallowing crap.

Thanks for following up akflyer. I had the EXACT same thing happen with my old original mechanical tach - overly optimistic RPM indications on the order of your errors. A new digital tach that is accurate to +/- 10 RPM really helped.

[akflyer]

Thanks for following up akflyer. I had the EXACT same thing happen with my old original mechanical tach - overly optimistic RPM indications on the order of your errors. A new digital tach that is accurate to +/- 10 RPM really helped.

The EDM 350 and optical tach read the exact same now. I still keep the optical velcro'ed to the dash right in front of me for back up.