taxi test exit criteria


wesisberg <wes@...>
 

Hi -

(Ok, third message to the group today - and sorry about the fionapple
alias)

What exactly should I find before calling taxi testing successful? I
hope to be able to finish in a week or two (having done about ten
hours in the last two months).

Under optimum conditions (reflexor full aft, mid-CG) I'm able to
maintain reasonable control using tailwheel, brakes, and/or ailerons
up to 65 mph ground and air speed (not yet testing past that pending
more serious first-flight prep). But how far should I go in testing
further configurations or speeds?

E.g., Brian Martinez wrote that his tailwheel stayed down at 60 mph
with neutral reflexor. Should I expect that? How about when I'm at
the forward CG range? What crosswind component should I try?
Obviously there are a number of parameters:

- ground speed, air speed, crosswind speed
- weight, CG, reflexor
- power and brakes, abruptness of application

I'd like to target any condition I'm likely to find myself in and any
situation where folks have found unanticipated behavior in their
planes. I think that includes an 8-knot crosswind, tanks close to
empty (light, forward CG), little to no headwind (i.e., fastest ground
speed), and fully loaded with little headwind (i.e., more mass to push
the wheels around). Does that cover things?

I'm also interested in targetted tests. E.g., for the reflexor I'm
considering taxiing with forward CG and the reflexor forward,
increasing speed very gradually just to the point where the tail/plane
gets light, to find out the actual difference in lift and tailwheel
purchase due to the reflexor. (Same for neutral reflexor.) For
aborts/go-around's, I've been doing abrupt power tests to see how the
plane responds. I've also tested some high-speed turns to find out
how much energy I can expect to lose and whether there are any
gotcha's. Does anyone test for oscillations? There's enough of a
bump in the runway to induce oscillation; should I avoid or try that?
(I've staticly tested the wheel alignment change when bouncing but
need to redo that under load.) It might help to know that my plane is
relatively light and has upswept main wingtips. I'm pretty sure it
would nose over if I went full power with forward CG at run-up. I
plan a series of nose-over tests at various weights once I get someone
to hold down the tail for me.

Obviously I'll prepare for, and plan to avoid, inadvertent first flight.

Thanks -
Wes

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