Pre-War Trim

[datema]

A friend is building a 1940 T-Craft and has a trim system that seems to be activated by a lever under the pilot seat. Any info? What does it attach to on the tailfeathers?
Datema

[Swick-T N7010S]

Re: Pre-War Trim

The trim tab is a seperate flying surface under the tail. There has been a lot of discussion on that topic lately. Just look at some of the previous post and you will find lots of information.

Mike

[VictorBravo]

Re: Pre-War Trim

There is another thread in progress on this issue. In short, the trim lever attaches to a pivot rod which moves two small "wings", which are mounted about 8 inches underneath the stabilizer. They are completely separate from the stabilizer and elevator.

The pre-war trim system is notoriously ineffective, which is why I am tinkering with making an improved set of these "flying wing" trim tabs.

Based on my recent (and ongoing) experiments, if you want to keep the airplane stock with no modifications, I would strongly suggest that you install a leather or rubber washer in the forward (under-seat) trim lever pivot bolt, to provide friction. Without this, you will find that you move the lever to trim the airplane and in many cases the air just pushes it back where it was. Adding a friction washer somewhere in this system will probably solve that problem, but the secondeary problem is that the trim tabs are not big enough and they will usually not give you the ability to trim for very high speed or very low speed.

My modifications are experimental, not approved, and are perhaps more extreme than others will wish to do. However, I do feel that a minor re-shaping and re-sizing would make a significant improvement and not raise too much suspicion. E-mail me privately for more info if you are interested.

To any other interested parties following my progress on the trim tabs, I have chosen to try adding area behind the pivot, rather crudely at this stage, and will report on the results.