Thorp Air Command - T18.net

I have found lowering the tail allows you to approach slower. Reference the discussion you had earlier with Bob Highley about wheel landing versus three pointing, and the tail being well below the mains as you approach on speed. Lowering the tail on the ground allows you to carry higher AOA into the flair without hitting the tail wheel.
Cubes

That's what I did from the start Cubes, I pushed some of the arc out of my tailwheel spring, it did 2-things. It lowered the tail a pretty good amount, and it set my tailwheel up to always have a tendency to roll streight. I learned to fly the thing with this configuration and it is well mannered on the Tarmac. But I have also flown others that are not set up like mine and they had no bad manners either. The spring being without some arc stops plate area from being in the wind also so I guess it did 3 things sorry bout that I mis spoke or I'm getting where I can't count. It will 3point just fine, that's my preference, full stall at 3-point position, I have the short gear legs and I learned on em so My setup is no better than those that are being used today, Guess I just got real used to using it ........Dan

'Feisty' originally had the flat steel spring pack and Maule tail wheel when I got it. The wheel must have hit the bottom of the rudder which has a little distortion from being pushed up. Some previous pilot must have had a hard tail wheel landing.
I would be concerned about removing some of the arc from the flat spring.
The Trusty conversion has been a success. The spring rebound frequency is slower, the steering is better, and the wheel is farther aft, beyond the rudder bottom.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Cubes,
Spring constant (k) is the applied force (F) divided by the spring displacement (x) [k = F/x]. Sounds like setting up a test stand and hanging some weights on the end of the rod and measuring how much the rod bends would be a solution to finding the spring rate. With a nonconstant cross-section, the math may be a little hard to otherwise determine the spring rate even if you had the tables for the steel and the heat-treating process it went through.

Spanky

I love it when Spanky spouts his gibberish! Ok. What do I need to do? But I'd think I would need a flat spring to compare it to, wouldn't I? My old one is on a Champ in California.
Cubes

Probably easiest these days to model with a CAD program like Solidworks and do a simple FEA. For others so inclined, crunching the numbers using Castigliano's Theorm is an option as well.

Jim

:-)

So, I really wasn't planning to do testing on this as I am kinda maxed. But if needed, I can hang weights on the LT spring and compare it to the AP Spring I have. I don't really see the need to compare it to the flat spring as most folks are moving away from those (and I don't have one).
Bob, do you need to see some data?
Cubes

Where's Spankys allowance for density altitude vs latitude?

Measure the distance from the outboard spring tip to the rudder bottom with the tail wheel off of the ground, now set the tail wheel on a weight scale, push down on the tail until you have 1" deflection at the spring tip between the rudder bottom, note the weight on the scale, there is your spring rate give or take a few #s...........Dan

Good idea Dan!
Cubes