Thorp Air Command - T18.net

Well, looks like I have to buy a set of new rudder cables. It's a Canadian thing; our rules require 1/8" cable on primary controls.

Before I go ahead and place the order, I was wondering if anyone has incorporated a rudder cable length adjustment mechanism on their airplane to accommodate different pilots.

D

The cables should have turnbuckles incorporated. I would use the long ones to maximize the adjustment you reference. If you make 'em too long, you will get into the tank support interference situation previously discussed, however.

_________________
Bob Highley
N711SH
SN 835
KLAL

Turnbuckles... indeed. Goes without saying. (Appreciate the tip on getting the long ones.)

I was thinking more like a two or three position quick adjustment like you often see in sailplanes..... probably not worth it.

(Nevermind!)

Dick,
An ajustable seat. My aircraft has '60 vintage Cessna seats on seat rails.

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Log on to Vans Airforce, there is an adjustable rudder system that they are installing in a RV.

Dick,

Wear high heels if you can't reach the pedals!!

Best regards,

Jim :-)

Prolly goes without saying, but the turnbuckles outa be at the rudder pedals, and not at the aft tiller. That sucks Dick......you'll have the equivalent of an A-10 when it's done.

_________________
Fraser MacPhee
N926WM
Serial #279-1
Angel Fire, NM (KAXX)

I Have to ajust my pedals every time I take off or land, sometimes frantically.....Dan

Dan, that was funny. Just the other day, I had a brain lapse while just a few feet off the ground. I decided I needed to readjust my tooshie in the seat....and in doing so I really kicked in rudder one way, then kicked it in the other way.....all worked out fine but what in the world was I thinking! Rudder is very sensitive!

Today I landed in a 80 degree x/w of 16 knots, gusting to 22! It was busy, but I had enough rudder!

Sorry for the thread drift........

No thread drift here at all, just a little cross wind as you stated Ryan.....Dan

Does anyone happen to know what drawing the rudder travel is shown on? I can't find it.

Currently my rudder skin contacts the right stabilator anti-servo tab arm screws before it hits the stop. That doesn't seem right. I'm trying to figure out where the problem is.

Dick,
See drawing 567, +-30 deg, the tab linkage installation is shown on 521.

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

Dick, check the stop and see if it is centered, check the lower rudder mount to see if it is centered, does it hit both stabilizer arms or just the on on the right? If it's just hitting one side somthing may not quite be centered just right . It sounds like an adjustment here or ther will correct it......Dan

I know everyone is dying to hear how this turned out. :-)

Looks like the -578 Rudder Stop was a little shy of material on the right side.

I also found an interesting problem with the left rudder travel. I could make the rudder go to the stop, but the force required to do so increased noticeably towards the end of the deflection. Turns out that the horn (mast) for the cable and spring on the right hand pedal assembly was made too wide, resulting in contact with the cross tube of the LH Pedal Assembly.

... and now, a DW rant: It boggles my mind that a such fundamental problem can exist on a Primary Flight Control of an 1100 hr. airplane. The rudder not contacting either stop should have been found during the build, the FAA (or DAR) inspection, 30 annual condition inspections, or any of the 100's of pre-flight inspections. Just saying.

We know of a Thorp t-18 that had been flying many years with a similar alarming issue. Due to a an encounter with a runway light, the fuselage had to have the rear section rebuilt. In the process, the fuselage was now 1/4" shorter than the plans show. "Not bad", You say. Well, when the push-pull tube was reinstalled, the stabilator up/down movement changed drastically to the extent that there was essentially no down movement. You probably could not break a deep stall if you wanted to. Luckily, this condition was spotted an a walk-around by some experienced Thorp eyes before trouble happened. A new rear push-pull tube fitting was needed to correct the issue.

_________________
Bob Highley
N711SH
SN 835
KLAL