Thorp Air Command - T18.net

This one's for Rich, but may apply to others:

Many, many incidents and accidents result from inadvertent flight while performing high-speed taxi tests. If the airplane tracks straight at 20-25 kts, it will track straight at higher speeds; no need to test that arena. If a known airplane (T-18) is within weight and balance limits and the flight controls are set in limits, it will fly properly.

The recovery from high speed taxi is nothing more or less than a high speed abort -- normally thought of as an emergency procedure! Pulling the power at high speed gives you a gyroscopic effect that you don't encounter in normal operation because you have rudder effectiveness in the landing regime. I have found that full rudder authority occurs above 45 and taiwheel effectiveness ends about 30.

Bottom line: Don't screw around in the "Dead Man's Zone."

_________________
Bob Highley
N711SH
SN 835
KLAL

Good info on the rudder effectiveness speed, but a little confused about the tailwheel not being effective below 30 ? I guess I should have given more info on my "taxi tests." They were conducted on a long and wide paved runway under adult supervision and the speed was kept below V1. Well below V1...25 on the GPS. A/C tracked straight down the runway and the braking was EXCELLENT ! I punked about the V1 speed, must be my younger years working for money.

This was not a "will it fly test" ( I know it will fly), but more of a "get to know ya test." The feel of the rudder pedals, braking action, throttle response, visibility during taxi, engine run ups, using check lists, leak checks and a new one that happened today...tail wheel unlocking during a tight turn. Just trying to remove as many variables from the equation prior to the first flight.

RB

Just to remind you, many airplanes have been wrecked doing high speed taxi testing, And if the engine has zero time on it you stand a good chance of over heating the rings and loosing the temper. Result, high oil consumption for the rest of it's life!

Rich,

Sorry for the confusion. What I meant to say was that the tailwheel looses effectiveness above 30 due to lose of friction. Undue back stick at this point will cause the plane to fly off below minimum control speed -- not good!

I can also attest to the ring distemper issue.

Sounds like you are ready to fly. Have fun!

_________________
Bob Highley
N711SH
SN 835
KLAL

Thanks for the info. about the tailwheel speed. Also good info about the rings. Yes it is a zero time engine. Good thing it has a 3 year warranty from Aero Sport Power. They cover everything on the engine except the paint. All temps have been in the normal range.

RB

Last evening I did a Rich B "Get to Know Ya" taxi test.
I only went up to about 25 or 30, as per this thread's advice. Some crosswind from the left, too much for a first flight. Maybe I shouldn't have done it. But it was 'a learning moment'.
Nothing unconventional, just a very light plane that responds to your wishes rather quickly?
I need to replace the Transponder antenna and work on the tail wheel some more before I think it's ready.

It is a very responsive airplane. Once you get used to it, you can't get enough of it. I recommend some training in type. if available, as it does respond faster than your typical, C-140 or Champ.
Have a ball!
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