From: gregt@col.hp.com (Greg Tarcza)
Subject: Re: Hi-Start
Date: Fri, 9 Oct 1992 21:33:13 GMT
Organization: HP Colorado Springs Division

egdorf@zaphod.lanl.gov (Skip Egdorf) writes:
> 
> After you stretch out the rubber tubing (holding onto the glider to
> keep the Earth from flying away until you are ready,) let go of the
> sailplane. 
> 
     Skip just hit my hot button (no offense, Skip).   NEVER, NEVER just
let go of your plane when launching on the hi-start!  I haven't been 
flying very long (2.5 yrs), but I have seem a couple of mangled planes
as a result of "letting go."
     I wrote an article for our local club newsletter just last month
on this same subject, so here it is - slightly edited as noted by "...":

          ...
	  When launching your bird on either a hi-start or a winch, 
     always expect the worst to happen: a broken or snagged line or
     a wind gust.  There are ways to minimize the impact of almost 
     any sudden development.
          A major cause of mishaps on a hi-start is a lack of initial 
     airspeed, usually resulting in a stall, wingover and crash. Always 
     throw your plane as you would for a hand-launch.  Keep the nose and
     wings level and use enough muscle to give it more than enough
     airspeed for flight.   A strong level toss will get you at least 
     part of the way up.  If you don't really know how hard you throw
     your plane when you launch, THINK ABOUT IT the next time.
           Airspeed is more important than altitude (assuming that the
     altitude is greater than zero).  Don't rely on the strength of the 
     rubber to increase your airspeed. You are always trying to balance
     potential and kinetic energy during a launch. Ideally you would like
     to hold a somewhat constant airspeed going up a winch or hi-start.
     In the case of the hi-start, you want all of the potential energy
     in the stretched rubber to be transferred to your plane in the form
     of altitude.  The pilot has absolute control of where the energy ends 
     up.  If your plane seems to be losing airspeed, push the nose down.
     You might not get as much altitude as you would like, but you will be 
     less likely to stall on the way up.  Ask your plane how it is doing
     as it is going up by feeding it small rudder movement.  If it 
     responds sluggishly or maybe not at all (I hope not), PUSH THE NOSE
     DOWN, it is losing airspeed and a stall is imminent.  If you are
     attempting a launch on a weak or questionable hi-start, you may not 
     have time to "talk" to your plane, so be ready to PUSH THE NOSE DOWN
     almost immediately after throwing the plane into the air.  Watch the 
     attitude of your bird. If it appears to be mushing along, PUSH THE 
     NOSE DOWN.  
	  ...
	  I have a few rules that I like to follow when launching.  You
     might give them a try if you have had problems popping off a hi-start 
     or stalling.  Keep in mind that I am still new at this,  but I have 
     never crashed or popped off a hi-start!  
          First, I like to add a couple of clicks of down trim before 
     launching on a hi-start. I start taking the down trim back out after
     the plane is about 200 feet up and still going strong. If you have a 
     tendency to point the nose of the plane up when throwing, THINK ABOUT 
     IT and keep the nose down to less than 10 degrees up. The pull of the
     hi-start or winch will rotate the plane almost immediately after it 
     is airborne.  Don't rush the process.
          And last, on a decent hi-start,  a good winch launch or in 
     moderate wind, I always like to see the bottom of my plane.  If the
     plane is perpendicular to the winch line, it may not be accellerating
     or even holding a constant speed in the forward direction.  If I can't
     see the bottom of the plane as it appears to be going straight up, I 
     will nudge the nose down a bit.
          ...
							  Greg Tarcza

Note: The above article was written the day after watching someone else
  point a brand new 2M Spirit up at 45 degrees and let go!  Fortunately,
  all he lost was a wing and a nose!     Good lift!

					Greg

===============================================================================
Greg Tarcza      WA2OOD                                               /
Hewlett-Packard Company                                              /
P.O. Box 2197                                                       /-,  /-,
Colorado Springs, CO  80901                                        /  / /  /
719-590-2471                                                      /  / /--/
                                                                      /
gregt@col.hp.com                                                     /
===============================================================================

Newsgroups: rec.models.rc