Message-ID: <004501beeb9b$774e21e0$06b8b6c6@gjpc>
From: "Gerard J. Cerchio" <gjpc@circlesoft.com>
To: <lancair.list@olsusa.com>
Subject: The efficacy of Taxi Tests
Date: Fri, 20 Aug 1999 23:06:01 -0700
Mime-Version: 1.0

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Hello all,

I have spent the last few days thinking about Dr Michael A Fopp's sad
experience with his 320 and after having reported my very successful
taxi
tests I must say something here in our forum about his comments on high
speed taxi testing.

No one can accuse me of rushing head long into my project.  Indeed, I
have
been constructing my aircraft for ten years.  I still have not flown
N333EX
due to testing and detail after detail.  I may be ready to flight test
my project
next week, given no more details show up.  CJ Stephens, a professional
test
pilot will perform the flight test, not yours truly.

Every flight test book I have read extols the virtues of high speed
taxi tests.
To me, they just make great sense.  I am testing a vehicle.  That
vehicle has
very specific phases of operation.  Phase one, it must sit on its
wheels and
not collapse. Phase two,  it must turn its propeller and not catch
fire. Phase
three, it must taxi to a place where it  is safe to perform phase four.
Phase four, it must turn its propeller with sufficient force and
consistency to
hurl said vehicle into the  air.  Phase five,  it must hurl itself down
a runway
with sufficient speed for the airfoil to perform said task of hurling
said vehicle
into the air.  Phase 6, it must enter the air.

Now,  I have spent some time getting to phase five.  I personally
believe that if
Dr. Fopp had spent more time in Phase four, his calamity may have been
prevented.  When I decided to it was time to taxi test 3EX I was bent
on
seeing if the aircraft would perform at speeds I had not ventured to
during
phase three taxi. My first desire was to see the airspeed gage ride
above the
peg.  I did this on the way to the runway.  I did not notice any
vibration or loss of
control so I requested the tower for permission to use the runway for
the test.

My second goal was to reach 40 knots with the throttle full to the fire
wall.
Given how much testing that it took to get that throttle to the
firewall, see earlier
posts, I was quite happy to be traveling at freeway speed down a
runway. I
believe that if I was hell bent in flight testing the aircraft at that
time that I may
have well been unable to counter an uncontrolled shimmy in the gear
given how
quickly the aircraft reached 40 knots. But being that my only objective
was to
reach a comfortably fatal speed that I would have been ready to pull
throttle
and apply breaks,

My second taxi run was to achieve speed that would be the projected
stall for
the  aircraft. I chose 60 knots, reached the speed, maintained it for a
while and
then backed off.  Still not a problem detected, I planed for a greater
then
a rotation velocity taxi with flaps in a cruise configuration giving me
a
margin of safety for saying on the ground.  Again, success.

I have to add that before I even taxied, that I had sent my strut to
Nieco for
a full overhaul and update.  I did this because A) I had one of the
older struts
in the word and B) I bled all the nitrogen out of the strut earlier to
keep the plane
level for setup and testing.

SOOO,  I recommend everyone rebuild their struts immediately, and by
all
means taxi, taxi, taxi.  (I did one more for good measure).

Gerard Cerchio

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