[LASS Soaring] "The CG Myth ANSWERED"

[GordySoar at aol.com]

I do know that the flyers I know who get some of the  best results have more
_Confidence_  :)  with a relatively more aft  CG than I do.  It could be
that moving the CG aft beyond a certain point  has the effect of
requiring a steadier hand to maintain stable  flight.
Don
 
Hi Don,

The phrase reward CG of the top pilots implies  that your balance point is 
right and theirs is unusual...yet its them that are  up on the score sheet.  
That doesn't only mean time but also landings, a  place where a squirrely model 
is a deficit.
 
When Smarty Jones showed up at Churchill Downs for the  new owners to see him 
for the first time, upon returning to the paddock the  trainer asked the 
jockey what he thought of him?

The Jockey exclaimed that he was fast and  touchy!

The trainer said,"I can fix that!" and he tied a short rope  between his back 
legs, and said,"That will make him more stable!".....or did  they find a 
jockey who was up to the performance of the horse?
 
Dumbing our sailplanes down to match our comfort  zone, is silly. Optimizing 
the sailplane then WORKING at learning to  become the pilot to match that 
investment is more fun.  Too many pilots get  the new super ship, then dumb it 
down with lead in the nose so that it 'feels'  just like the ship they got rid of 
...then wonder why their scores don't seem to  change?
 
Want your scores to improve?  Do the  un-comforatable thing, learn to fly the 
new plane the way it was designed to be  set up.
 
Remember if you have one dot more lead that is needed to make the  plane fall 
foward, then it will be falling forward and nose down.  That  means for it to 
fly hands off level, at its normal level flight cruise speed,  some up trim 
will be needed to hold the nose against the pull of gravity.
The  problem with that is that any increase in airspeed will either empower  
the elevator to direct the nose up,  and any decrease will allow gravity to  
pull the nose down. Instead of having a model that tells you about lift or sink 
 you have a model that tells you about airspeed changes...and you can never 
learn  to read air with the big dogs if you have a model set up to lie to you 
about the  air.
 
"Rearward CG" Everyone knows that the top guys seem to  have their models set 
up that way.  Of course that implies that they set  their models up weird and 
unstable, and that all of you  have your models  set up 'right'. Their models 
are the exception and yours are the norm.
In  what strange world would any contest pilot want their models set up so 
that they  are 'unstable' or 'hard' to fly?  Think about it guys, they want to 
win,  they don't want to do it the 'hard' way!
In fact if your model is balanced incorrectly for the task, then  its your 
model that is the set up to do it the hard way.  IF it were the  easy way, 
they'd all do it that way!
 
When David Hobby said that he likes a 'rearward CG', but in light  air 
conditions makes his model more nose heavy....what the heck does that  mean?  It 
means that he has his sailplanes balanced properly for the 90% of  the task but 
sometimes adds a dot of lead to dampen its action during times when  there are 
a lot of tiny puffs of lift that are nearly impossible to take  advantage of, 
so wants to fly thru some of that to air strong enough to force an  indication 
of lift. It doesn't mean make a crooked plane crooked'r  :-).
Confidence is the result of a properly balanced TD ship. But since CG  does 
not affect performance, that confidence comes from something other than  some 
imagine value of added performance.
 
A model properly balanced for TD work affects COMMUNICATION.   You end up 
with a model that doesn't lie about lift and sink.  Instead of  indicating 
airspeed changes due to the up trim needed to keep an improperly  balanced ship 
level at hands off level flight speed, you end up with a model  that doesn't talk 
about slow or fast, instead you have a model that only tells  you about lift 
or sink.
 
That is how the big dogs end up getting their time....they  cheat!  They have 
a helper telling them about conditions, signaling when to  circle and when to 
scoot.
 
Want to be comfortable, keep setting your new super ships up like  the junk 
you just sold, you know so it 'feels' good to you. You know so its  'stable'. 
But don't wonder why your scores stay the same.

Want to win, or  at least improve your scores?  Get a helper...one that tells 
the truth.  :-)
 
And by the way, you can not balance a TD ship on a teeter totter in  the 
garage, it can't be measured with a ruler.  Our sailplanes fly, and the  only way 
to figure the balance point is to have them going forward...at NORMAL  HANDS 
OFF LEVEL flight speed.  Last I checked diving increases airspeed  beyond any 
moment in task flying...so why would you do that?
Check back in  the RCSE archives. JW explained how to find the perfect 
balance point for TD  ships...and its based around testing the model at normal hands 
off level flight  speed.
 
So does your plane tell you about lift and sink or airspeed? When  your 
model's nose goes up, is it because of airspeed or sink? Do you want to be  
'comfortable' or getting your times and landings?
 
Finding the correct TD CG is not about performance....or  'feel'.
Gordy
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