New Nose Wheel Fin

[Boatguy]

Let's revive the original thread and leave this one to the fin.

Are exceptions for discussing Teslas OK?

Touché!

My instrument DPE spent half the oral exam discussing Tesla's so I think it is an FAA approved digression!

[Rick]

Let's revive the original thread and leave this one to the fin.

I moved the vent-related posts to the Air Vent thread to make them easier to find in the future. I duplicated Mark's post with all the pictures to the other thread and also left it here. Hopefully it will all make sense!

[AlSimmons]

I need to purchase a nose wheel fin for our new 2020 DA40-180 and I am not sure how to do it.

[Boatguy]

I need to purchase a nose wheel fin for our new 2020 DA40-180 and I am not sure how to do it.

PM Pilot55.

[firedwg1]

I was thinking that the nose actually will weather vain naturally during flight. Cruise on the mt 3 blade prop is normally 143kts.

What’s the benefit of adding the nose fin?

[Boatguy]

I was thinking that the nose actually will weather vain naturally during flight. Cruise on the mt 3 blade prop is normally 143kts.

What’s the benefit of adding the nose fin?

Numerous owners, myself included, have experienced that the nose wheel stays "cocked" in one direction or the other, resulting in the plane flying in a slight slip throughout a flight with one wing dipped unless the pilot provide rudder input to coordinate flight. The fin applies sufficient pressure that the nose wheel aligns with the direction of flight so that the plane flies straight and level.

[firedwg1]

Thanks for explaining, it seems to me that if you input the correct rudder pressure for coordinated flight the fin would not make a difference on the nose gear.

The nose gear wouldn’t the nose gear still weather vain towards the crosswind?

V/r

[Boatguy]

Thanks for explaining, it seems to me that if you input the correct rudder pressure for coordinated flight the fin would not make a difference on the nose gear.

The nose gear wouldn’t the nose gear still weather vain towards the crosswind?

Rudder pressure, basically turning the rudder at the aft end of the plane, offsets the pressure of the nose wheel, acting as a rudder, on the front of the plane.

No, the nose gear does not always weather vane towards the crosswind. If it did, this thread would not exist, Pilot55 would not have gone to the trouble of creating a solution and I would not have installed it on my plane. If you don't have this problem, you are lucky and should ignore this thread.

[Rich]

Thanks for explaining, it seems to me that if you input the correct rudder pressure for coordinated flight the fin would not make a difference on the nose gear.

The nose gear wouldn’t the nose gear still weather vain towards the crosswind?

V/r

There is no effective "crosswind" relative to the aircraft movement through the air once you clear the ground unless you're slipping/skidding.

There are several pictures/videos on other threads showing the behavior of the stick nosewheel canting to the side after takeoff, apparently all the way to the lock. I recall one where one of our folks taped little string to the faring and showed it in flight, canted to the side, with the strings draped crosswise to the spine of the fairing. It sits there throughout the flight because this is a stable position, even though it is not the least drag condition. The only thing inhibiting this movement is the friction of the spring washers, which is periodically adjusted via the pivot nut to the spec in the AMM. The fin changes this, so it is stable with the nosewheel aligned with the airflow from the front, the least drag position.

I have one of the old fat-gear planes with a forward CG. It benefited significantly in cruise speed with the addition of the Powerflow. Yet my cruise speed would be inconsistent. Moreover, in cruise with the AP, the plane would often fly with one wing low. I added the fin, adjusted the rudder trim to be neutral (it had a right-rudder set to it). Now my old, slow DA40 at cruise flies wings-level, feet on the floor, ball centered and delivers completely consistent cruise speeds. In stable air I see 143 KTAS at 8,000 ft DA at WOT/2400 RPM - always.

[Soareyes]

The nose gear wouldn’t the nose gear still weather vain towards the crosswind?

V/r

I recall one where one of our folks taped little string to the faring and showed it in flight, canted to the side, with the strings draped crosswise to the spine of the fairing.

Your hopes for a weather vane effect are entirely logical but alas, in vain. That’s what makes this problem so vexing.

Along that vein, here is a blog post on the subject with some videos I made back in 2013:

http://da-40.blogspot.com/2013/10/fly-l ... g-low.html