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<DIV><FONT face=Arial size=2>Bob</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Correct on instrument methodology. You may be
correct regarding observed readings also. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>However, very high roll rates seem not to generate
the same speed reading effect. The pitot extends about 3/8" forward the center
of the wing LE in my installation. I've not seen any difference in normal speed
data with it varied 1/4" or so from that position.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Pressure anomalies will definitely affect the
altitude sensor, however I don't see the same "signature" on downline snaps.
I've not been specifically looking at snaps to this point, the data were
generated flying the P-05 sequence. I plan to look at this further in a
different (more expendable) airplane with a G sensor also. Possibly that sensor
can be oriented to provide pitch load and thrust (longitudinal) accel / decel
info. (Should receive sensor in the next couple of days.) BTW, data rate is
10x/sec.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Earl</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=bob@toprudder.com href="mailto:bob@toprudder.com">Bob Richards</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, January 14, 2005 2:38
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Pattern Help</DIV>
<DIV><BR></DIV>
<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 <ehaury@houston.rr.com></I></B>
wrote:</DIV>
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<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><FONT face=Arial size=2></FONT> </DIV>
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