Posted for "DJ Molny" <djmolny@yahoo.com>:

Mike -

The DG is not a big concern, since your rate of yaw isn't very high in a
barrel roll.  The AI may tumble, but it should recover from on its own
within a minute or two.  As far as potential damage goes, the AI is unlikely
to be harmed by occasional smooth low-G maneuvers.

So much for gyros.  Now it's soapbox time.

Folks, every year an unfortunate number of pilots are killed performing
aerobatics.  While every airshow accident gets coverage on the 6 o'clock
news, many more fatalities occur among ordinary GA pilots who undertake some
casual acro maneuvers without adequate training.  Barrel rolls are one of the most benign aerobatic maneuvers you could
attempt.  Nevertheless, pilots still screw them up regularly.  For example,
many pilots stop rolling and pull back on the stick when inverted,
performing an unintended Split-S.  Another screw-up mode is failing to pitch
up adequately.  For pilots who normally fly +/- 5 degrees of pitch, 15
degrees is alarming, 30 is terrifying, and 45 just ain't gonna happen.  So
they initiate the roll without sufficient pitch-up, resulting in an extreme
nose-down attitude when the roll is complete.  Either way, both airspeed and
G-loads build up very rapidly, and it's easy to lose 1000-2000' of altitude.

By this way, these are not old wive's tales -- almost every non-acro pilot
that I take up for an aerobatic ride makes one or both of these mistakes on
their first few attempts.  Some additional examples:

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20010209X00430&key=1
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20030918X01558&key=1
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20030701X00990&key=1
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20010223X00508&key=1
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20010214X00453&key=1


So please, if you want to do some acro in your own bird, get a little
training from someone who knows what they're doing first.  That could be an
aerobatic flight school (see http://www.richstowell.com/howto.htm), a
military-trained pilot who is experienced with acro maneuvers in GA planes,
or a well-respected member of your local aerobatic club (www.iac.org).  And
be sure to review FAR 91.303 lest the Feds violate your ass for doing acro
where you shouldn't.

Thanks for listening.


Regards,
DJ Molny, Extra 300/L
Rocky Mountain Aerobatic Club
(Lancair someday)