Safe Gyro or not?

[drleon]

i am looking at Jukka's Jt-11
if you look at the side view it looks like this gyro might have yaw or roll problems
as i understand it would be wise to have a 1/3 front to 2/3 rear distribution of surfaces to prevent problems in flight

what are the opinions out there

leon

[Aviomania]

Originally Posted by drleon

i am looking at Jukka's Jt-11
if you look at the side view it looks like this gyro might have yaw or roll problems
as i understand it would be wise to have a 1/3 front to 2/3 rear distribution of surfaces to prevent problems in flight

what are the opinions out there

leon

The Yew Stability should not be bad in this design. The yellow shade is about the area behind CG, and the 2 extra yellow shades are the vertical fins that are at the tips of the HS. It’s also a tractor.

I personally prefer 3/4 area behind CM unless I am building an aerobatic aircraft

Any suspending fuselage without any aerodynamic stabilizing devises (like wings), that has big side area, will have roll problems from side gusts or when you try to fly sideways (side slipping). I thing that this design qualifies for big flat side area

[WHY]

HI drleon

Your perception of the 1/3 --- 2/3 ratio is right on target and and as aviomania says he likes 3/4 behind is really good.

Jukka is a very good designer and what saves this design is the twin rudders spaced out into the prop slip stream, a dead engine landing with a side wind would require a "fly on " landing with some foward speed for stability, also the other good reason for this "good front to back ratio" is the potiental for a flat spin on a steep slow maximum performance climb out. this was the problem with the Eich Je-2, small single rudder and about a 50 -50 ratio between the propellor lline and the rudder hinge line. I had the privilege of getting to know Jim Eich, a great guy, and in one of our conversations he told me about having such a condition develope and was able to walk away from it although the craft was damaged. I have always been interested in the tractor gyro and Jim knew this and was always ready to help with any experience or knowledge he had that would keep someone else out of trouble.

This is the kind of help that I have gotten from many PRA members over these many years that I have been working on my tractor ( and still have a couple of years to go, I think).

Tony