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I just flew my first long distance cross country flights from Michigan down to Florida. On most flights at 8-9000 ft I have to apply right rudder to center the ball, to varying degrees. Is this corked nose wheel or trim tab caused? I also had a noticeable nosewheel shimmy on one landing which may have been not enough backstick on rollout but can that be something else?

40flyer wrote: ↑Mon Aug 19, 2019 3:25 pm I just flew my first long distance cross country flights from Michigan down to Florida. On most flights at 8-9000 ft I have to apply right rudder to center the ball, to varying degrees. Is this corked nose wheel or trim tab caused? I also had a noticeable nosewheel shimmy on one landing which may have been not enough backstick on rollout but can that be something else?

The deal with adjusting the trim tab vs. holding rudder is more variable than just setting and forgetting. With Bret's fin on my nosewheel, at 6,000 - 9,000 ft. it's basically feet-on-the-floor cruising. (Note that 9,000 ft. often translates to something like 10,500 ft. DA.) But recently at 11,000 ft. (12,500 ft. DA on this particular day) I had to hold some right rudder to center the ball. In a high-speed descent I'll find I need to add left rudder. This is entirely to be expected, per common literature on p-factor.

Once in a while I'll have some kind of shimmy show up on landing rollout. It's maybe 1 time out of 20 landings. In theory the nose wheel pivot spring load is supposed to damp these out. I suspect that some perfect combination of tire pressure/temperature, CG/weight, and maybe too fast a nose wheel touchdown gets it oscillating.

Also, don't forget to check the nose wheel pivot tension, which can have an effect on both the "corked nose wheel" problem and the tendency to shimmy on rollout. In my experience, you want to make sure your tension is set to the high end of the allowable range.

Bret,
How's the version for the 2007+ planes coming along?

I've had the Bretfin for months now. One thing for certain is it produces repeatability of cruise speed at any given set of conditions. And my plane is reliably faster in all cruise situations than stock. Today: ~2,525 lb. GW at takeoff, 10.8K DA, 9.7 GPH yielded 142 KTAS. Book is 128 for this condition (remember, I have an '02 - the old, slow variant). This is PF + the magic fin. The latter, as I said, makes these numbers repeatable. Prior to fitting it I would find cruise speed to be somewhat unpredictable.

One mod I made was to paint the fin with rattle-can Krylon White Gloss and waxed it. Otherwise the fin was a bit translucent and has a somewhat rough finish which tended to be fond of dirt, fingerprints, etc. Now it looks like it belongs there.

Anyone able to get a Bretfin for the newer year planes? Haven't heard an update from Bret in a while.

smoss wrote: ↑Sat Nov 09, 2019 12:06 amAnyone able to get a Bretfin for the newer year planes? Haven't heard an update from Bret in a while.

I flew my DA40 down to meet Bret at his home airport back in July, and left my NLG pant with him to scan (I have the 2007 variant). He shipped it back a couple weeks later and said he was working on the mold. I've ask a couple of times since then, but I haven't seen anything yet, or heard anything since September. His last post here on the DAN was back in July. I hope everything is ok with Bret...

He sold his Diamond so perhaps he lost interest?

As an alternative to the fiberglass fin, how about 3D printing one? I'm no expert in the field, but seems like it would be quick and easy to mock it up and whip them out if you had the skills. Any comments from 3D skilled folks?

The last message I received from Bret back in July said he "had the master completed and it fit great". I'm not sure what his process was, but possibly if we could get this 'master' someone else could pick up this project - maybe someone with 3D-printing skills, as you suggest? I will reach out to Bret once again and see if I get any response.