wing tip shape (now Knife Edge Trimming!)

[John Pavlick]

Keith,
 I agree - well sort of. Although I too suffer from the philosophical
problem of using computer mixing (among others), sometimes there's nothing
you can do if you didn't build the plane or have plans etc. Ideally, the
design should be flight tested by the designer before distributing it to the
market. Any bad tendencies should at least be minimized. At least that's
what you expect when you spend a lot of money on one of the more expensive
pattern ARFs. In today's age of what I call "Hurry Up, Hurry Up, F#@! It Up"
we're lucky the parts are even glued on the cheap ones. I've had a few
planes that roll couple with the rudder quite a bit. Since it's too late to
"remove" dihedral I had to "mix it out". Certainly a lot less work to fly
than the alternative of manually mixing ailerons and rudder when making line
corrections. When I do a review for a magazine, I always mention any bad
traits or trim idiosyncrasies. I wish more guys would do this. There's
nothing worse than reading a review of "a great airplane that flies like a
pattern ship" only to find out that it just looks like a pattern ship.
Luckily the radio can save the day, but it shouldn't have to! Joe Bridi used
to build several prototypes before publishing plans or releasing a kit. His
planes fly very predictably. Some were better than others but certainly a
good deal of time was spent on the design before he felt it was ready for
the public. Maybe it has something to do with putting your name on it. Has
anyone ever met Mr. "Rising Star ARF"? I wonder if he flies pattern...

John Pavlick
http://www.idseng.com

 -----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Keith Black
Sent: Friday, November 26, 2004 7:39 PM
To: discussion at nsrca.org
Subject: Re: wing tip shape (now Knife Edge Trimming!)


  OK, now I'll rant about the mixing issue. I understand that the "ideal"
plane should not require any mixing rudder to elevator or ailerons. But if
your plane has those bad tendencies I say MIX THEM OUT! Jeeze, why do you
want to make your job harder based on some philosophical problem with using
computer mixing? Hey, does the stealth bomber have any mixing? How awful if
it does, we should turn that off and let the pilots deal with it manually!!!

  OK, I know that's ridiculous, but my point is that I think it's silly to
avoid mixing just because the plane "shouldn't" need it.

  Some will argue that any mixing you do to correct one problem will cause
problems in other conditions. In some cases this may be true, and I
certainly wouldn't leave the plane completely out of alignment and try to
compensate for a crooked plane with mixes, but a tuck here, a nip there...
wait that's the cosmetic surgery rant... what I mean is if your plane tucks,
pulls or rolls with rudder... mix it out! Then buy a new plane in hopes that
it will be perfect, then when it's not, put in the mixes again and never
admit it ;-)

  Keith Black


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