(Thought I'd move this to its own thread...)jrenwick wrote:I agree. When I changed my A65 engine out for a C90, I found there's never enough nose-down trim with the stock system.N9149A wrote:Doug I don't know if I'd do that. The Cub trim system (jack screw) is considered a week link at least for aerobatics and is one of the first things removed when a Cub is built for serious aerobatics. Thought you might want to know that.doug8082a wrote:. The Hatz is designed to have a trim tab, but I plan on installing a Cub trim system.
As you get into more powerful engines and other mods, it gets worse. Super Cubs have even bigger engines, plus flaps. A mechanic I know well believes this was the cause of a fatal PA18 accident locally: Cub driver executes a go-around, and stalls when the flaps are raised. Trim was found fully nose-up in the wreckage. Mechanic thinks the pilot might have saved the situation by reducing power and putting the flaps down again, long enough to retrim. As it was, the elevators apparently didn't have enough oomph to overcome the nose-up trim.
If the design calls for a tab, I'd want to stick with it!
Best Regards,
John
Thanks guys... good to know . This is what makes this forum such a great resource.
There are a couple reasons I'm thinking of changing the trim system:
1. Installing the Rotec radial will lower the thrustline a few inches so I thought being able to alter the angle of incidence of the stabilizer would make sense. There have been a few Hatz's built with the Cub trim system. However, there have also been several Hatz's with radials installed that did not go that route and according to some in the Hatz world the change in thrustline really doesn't affect it.... Soooooo , maybe it's not such an issue after all?
2. I'm not that crazy about the current trim system design for the Hatz which involves essentially a push/pull cable arrangement that doesn't appear to have much ability for "fine tuning" the trim like you can with a trim crank or wheel arrangment.
3. This one is strickly cosmetic, but I don't care for the appearance of the trim cable kinda hangin' out there at the tail.
Anyway, I have no problem staying with a trim tab arrangement, I'd just like to have one that I can "fine tune" a bit better and might have a cleaner appearance. As for the thrustline issue, if it IS something I need to address then there is an alternative there as well that has been done on other Hatz's... I was thinking that incorporating the two (ala the Cub) was a workable solution, but now it doesn't sound like such a good idea.
I'm open to suggestions. Ideas anyone?