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Bob:<br>
Probably correct. I've flown light planes wherein the airspeed
indicator would read ridiculously low at high angles of attack. The
high angle that the pitot tube is presenting to the relative wind,
(which distorts the apparent shape of the inlet) won't allow the full
pressure to pressurize the tube. Hence, false airspeed readings.<br>
Bill Glaze<br>
<br>
Bob Richards wrote:<br>
<blockquote cite="mid20050114203844.84876.qmail@web12403.mail.yahoo.com"
type="cite">
<div>Earl,</div>
<div> </div>
<div>I'm not familiar with that device, but I will make two
assumptions. 1) The altitude transducer works on barometric pressure.
2) The pitot tube works just like on a full scale plane.</div>
<div> </div>
<div>I suspect the unexpected zero airspeed has to do with the
airflow at the tip of the pitot tube not being parallel with the pitot
tube due to the high rotational speed of the snap. In an extreme case,
the airflow traveling perpendicular could actually cause a vacuum in
the pitot tube.</div>
<div> </div>
<div>If the altitude measurement works on barometric pressure, there
must be a static air source. I suspect the vertical speed anomaly is
caused by a change in the static air pressure due to the sudden change
of airflow around the airframe, including the static air source.</div>
<div> </div>
<div>Just guesses.</div>
<div> </div>
<div>Bob R.</div>
<div> <br>
<br>
<b><i>Earl Haury <a class="moz-txt-link-rfc2396E" href="mailto:ehaury@houston.rr.com"><ehaury@houston.rr.com></a></i></b> wrote:</div>
<blockquote class="replbq"
style="border-left: 2px solid rgb(16, 16, 255); padding-left: 5px; margin-left: 5px;">
<div><font face="Arial" size="2">While recently evaluating engine /
prop combinations (very top secret), I noted something that looks
useful regarding snaps. During both up and downline snaps the speed
signal drops to zero for a period of time roughly equivalent to snap
duration. It appears that possibly airflow separation from the wing
includes the pitot tube. Upline snaps also show a marked decline in
ascent rate during the snap. </font></div>
<div> </div>
<div> </div>
</blockquote>
</blockquote>
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