trim for take off and landing

I have a 180 hp Supercub with Borer prop, and have experimented all over the map with trim. I have also heard lots of hanger talk, mostly by folks that are not really experienced off airport pilots, and opinions are all over the map on trim. What are the pros and cons, for soft or very rough fields, for trimming about 8 turns forward of center, and controlling tail height off of the ground with power and elevator, for an airplane at gross. This is how I am doing things right now, for both take off and landing. jp

JP

I don't trust my indicator so I will crank my trim full forward then set it by cranking it back 8 or 9 turns.

Cub_Driver

Just a note - My trim cable busted on me last summer (i'm on floats) and it took six weeks to get a new one! I wasn't done doing my fishing trips to Canada (the fishing was just too good).

I adjusted my jack screw to trim for level flight @ 2300 rpm and saftey wired it there. I figured that my stick preasures would be quite heavy during landing as a result. What happened is that when I got down to anything les than 60mph indicated the plane was getting more induced drag, then I would go to the first notch of flaps and Wala! fly hands off! I mean realy!

My previous plane I built was a Model IV Kitfox with a 912 on floats, It didn't have a trim! The stick presures on that plane were REALY light - makes my 12 feel like a semi truck.

Discovered that I don't use trim much other than cruise. The transition from cruise to flaps requires some back pressure on the stick but it's not for very long and once the flaps come on I'm pretty neutral again. I tend to use more when I'm on floats or if spending a lot of time in slow flight.

PA-18 150

In a cub I use the trim for cruise and after flaps are extended it is pretty close to trim again, like already mentioned.

In other airplanes I intentionally trim for cruise and fly with heavy controls during approach and landing. My reasoning is that I use the stick force as my airspeed indicator. As I approach the stall the stick force goes to zero, this allows me to work close to the stall with a reasonable level of comfort. It also allows me to keep my head up and my eyes out keeping ahead of the trees or snags that I'm working near. It works really well for me.

Thanks Kelley - I'm going to practice that (@altitude)

trim

A note of caution on using turns of the crank to track trim... a few years back I was flying in southern Arizona, and the Cub picked up enough of that abrasive dust on the jack screw threads that the trim cable just slipped in place with no actual movement on the trim (no turns on the jack screw) so lots of thurns of the crank and no or very little trim change. Since then I have tracked both crank turns and the trim indicator, and every once in a whille I also verify that the jack screw is actually turning and producing trim changes as part of the pre-flight.

By far most of my landings are power off, high, flaps(maybe), slip, and either three point of wheel, depending on cross wind. However, if the strip is going to be very rough, I am trying to work out the most foolproof way to keep the tail wheel up out of the rocks and the speed absolutely as low as possible... hence the trim forward and power on landing drill that I asked about...particularly at gross. I have a CC Top Cub with the 2000 kit and all sorts of extra places to pack cargo, so stall can get up over 50, some significant weight is on the tail wheel, and this has me thinking about this issue a lot more than when I am very light.

deleet

Good topic.

My personal technique is to touch my right middle fingertip against instrument panel, and crank the trim/stick to where my past experience indicates correct climb speed/angle of attack for my gross weight and c of g condition will be. For my stubby little hands on most of the 'cubs I've flown, this is usually the heel of my hand, for sorta Vx for y'all that are into that nomenclature. Usually less than a half crank to correct.

You don't have to look at the indicator, it's right there in your hand. And if the cable slips, as previous poster noted, you pick it up right away.

I love the Supercub trim system.

Thanks. Cubscout