From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Re: AW: MT-Propeller
To: lml
Date: Tue, 12 Sep 2006 18:48:23 -0400
Message-ID: <web-1400016@logan.com>
In-Reply-To: <1158090941.450710bda79b2@webmail.grandecom.net>
References: <1158090941.450710bda79b2@webmail.grandecom.net>
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Posted for mmcmanus@grandecom.net:

  A couple of points to add concerning parachutes.
  
  If you think about getting out of an airplane at 400', you are probably too
  late.  In skydiving the recommended altitude to initiate emergency 
procedures
is
  1800' agl.  Mr. Molny is correct that the parachute MAY open in about 400',
but
  if that is your decision point to get out of an airplane, then you are
probably
  too late by the time you exit.
  
  As far as exit speed.  I have jumped out of 130s and 141s that were 
traveling
at
  about 130+ knots or so.  First, there is an air deflection door that
  is about 20" wide if memory serves.  That helps to keep you from bouncing 
off
  the side of the fuselage behind the door.  Second, when you get in the air,
or
  relative wind as it is called in skydiving, at that speed the wind feels 
like
a
  large piece of plywood that slaps your entire body.  Honestly, if you aren't
  able to jettision a forward hinged canopy like on a Lancair or RV, it's
pretty
  unlikely that you will be able to exit the airplane, especially at high
speeds.
  
  You will indeed slow down to terminal velocity which is about 176'per second
or
  around 120 mph.  However, that assumes a flat and stable body position.  If
you
  are tumbling or somthing else, your terminal velocity will be higher.
  Although
  reserve failures are very rare, it is possible, so be sure the reserve is a
  category B, which is rate at 150 mph (or is it knots?) for a given weight.
  Keep in mind that you will probably pull the ripcord while you are not in a
  perfect body position.  Most malfunctions and failures are due to poor body
  position during deployment, so the higher rated reserve is a good idea for
this
  reason as well.  Also, the parachute WILL open faster (and harder) at higher
  speeds.
  
  Also, I don't know of any drop zones in the country that would train you on
  round parachutes so that you'll know how to steer an emergency parachute.
  Everyone uses square parachutes now, even for students.  And the reserve is
  most likely a square parachute too.  You can probably buy a square reserve
for
  a seat or back emergency rig, but I think that would be the exception.  Most
  emergency rigs still have round reserves.
  
  Matt McManus
  LNC2 360