Hi Jojo,
I wonder how many folks are as "precise" (OK - anal) as I when it comes
to elliminating control surface slop. Here are some things to think about:
- As DP points out geometry is critical. The shortest arm on the servo
to achieve the surface throw required is the best way to maximize
machanical advantage and achieve better than rated torque (remember -
the spcs rate the torque with a servo arm that is 1" from output shaft
to load attachment).
- Zero bends in the pushrods from servo to control surface horn what-so-ever
- The holes in the servo arms and control horns start out slightly
smaller than the pins on the clevises and I work them in (along with
gear slop these holes will eventually elongate)
- When the cover is secured over the servo, a dab of Goop between it and
the servo case absolutely ensures zero servo deflection under any flight
maneuvering (upper skin buckling). If there is a significant gap between
the cover and the servo case, a little end-grain balsa can make up the
difference. BTW, after carefully fitting the servo covers I use GOOP
(very sparingly) to attach them to the wing surface. Looks way better
than tape, and easily removable.
- In the fuse I elliminate the servo grommets and eyelets, and cut the
openings to fit very snug around the servo case. I then use Goop to hold
them in. After catastrophic airframe failures at speed, the Goop has
always held whatever I glued in, and not failed.
That's it for now...
Jo Grini wrote:
What is also very important in our world is slop. The well proven DS368
is a very cool servo that can take a lot of beating. But after a lot of
"hammer jojo ground breaking" they will get sloppy. I hear there is a
DS3068 out of the factory now with output ball bearing that should fix
it ;-)
Hilsen (Regards) Jojo
NEW: www.jojoen.no
----------------------------------------------------------------------
Date: Wed, 22 Feb 2006 12:47:08 -0600
From: "John Diniz" <[EMAIL PROTECTED]>
To: "Simon Van Leeuwen" <[EMAIL PROTECTED]>,
<soaring@airage.com>
Subject: RE: [RCSE] Servo Performance - Real World
Message-ID:
<[EMAIL PROTECTED]>
Good post Simon
<-----Original Message----->
<From: Simon Van Leeuwen [mailto:[EMAIL PROTECTED]>
<Sent: Tuesday, February 21, 2006 10:37 PM>
<To: soaring@airage.com>
<Subject: [RCSE] Servo Performance - Real World>
<<<<Remember...the OEM specifications are derived at a fixed voltage =
with=20
whatever the current the servo desires from the power supply to=20
determine maximum available torque (this commonly recognized
measurement =
is taken @ 1.0" from the output shaft to move a load a fixed
distance).=20
No matter what, the servos in your aircraft will NEVER come close to =
this.>>>>>
Correct, on the 1" measurement from the center of the output shaft. FYI =
on JR servo testing here at Horizon we test torque ratings with actual =
JR battery packs, both 4 and 5 cell, running through either a servo =
tester or a receiver. Usually a 3000mAh.
<<<<If your goal is to see the best flight performance from whatever=20
airframe you employ, don't scrimp on the electrical system.>>>>
Don't forget the linkage geometry and setup as well.
JD
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--
Simon Van Leeuwen
RADIUS SYSTEMS
PnP SYSTEMS - The E-Harness of Choice
Cogito Ergo Zooom
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