Did anyone else notice that the calculated flap servo torque requirement (62
in-oz) is higher than the specs on all commonly used servos other than the
Volz Micro Maxx HP. The JR DS368 is spec'ed at 53 oz-in. The thin wing
servos, JR DS-168 and Hitec equivalent at 46.6 oz-in.
Two comments:
1)
What about elevator loads? And elevator servo moment? How would
that be calculated?
The all-moving Supra stab is aerodynamically balanced,
so the stab servo loads from the airload are minimal.
The only loads the stab servo will see is due to the
inertial load when the boom cracks the whip in
At 09:23 PM 2/21/2006, Mark Drela wrote:
The all-moving Supra stab is aerodynamically balanced,
so the stab servo loads from the airload are minimal.
The only loads the stab servo will see is due to the
inertial load when the boom cracks the whip in the zoom.
That is one of the reasons my
: www.jojoen.no
--
Date: Tue, 21 Feb 2006 18:52:58 -0600
From: S Meyer [EMAIL PROTECTED]
To: Mark Drela [EMAIL PROTECTED], soaring@airage.com
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
Message-ID: [EMAIL PROTECTED
the switch.
don
-Original Message-
From: Mark Drela [mailto:[EMAIL PROTECTED]
Sent: Saturday, February 18, 2006 11:08 AM
To: soaring@airage.com
Cc: [EMAIL PROTECTED]
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
Molded Supra launch hinge moments are listed below
Mark I enjoy reading your posts, very interesting. Makes me think of Spock. :-)
What about elevator loads? And elevator servo moment? How would
that be calculated?
At 10:08 AM 2/18/2006, Mark Drela wrote:
Molded Supra launch hinge moments are listed below,
for a 200 lb tow load (hard
@airage.com
Cc: [EMAIL PROTECTED]
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
Molded Supra launch hinge moments are listed below,
for a 200 lb tow load (hard F3j launch). For smaller
tow loads, hinge moments will be proportionally smaller.
wing camber = +10 deg
rudder defl = 30
This really gets one thinking about the flap servos
and what one is/has
used
for flaps.
99.9% of you guys will never build the line tension
Mark is referring to.
But...this brings to light a thread from awhile back
regarding servos and being smart about your linkage
geometry... design your
In a message dated 2/21/2006 10:44:21 P.M. Eastern Standard Time,
[EMAIL PROTECTED] writes:
99.9% of you guys will never build the line tension
Mark is referring to.
AMEN! Good Lift!
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On Fri, 17 Feb 2006, Michael Neverdosky wrote:
I think I got off by a power of ten so things are not as bad as my
numbers make it but the idea of checking to see what is really needed
so I can use enough wire without just throwing more wire at it is
sound.
Anybody know the full stall current
Molded Supra launch hinge moments are listed below,
for a 200 lb tow load (hard F3j launch). For smaller
tow loads, hinge moments will be proportionally smaller.
wing camber = +10 deg
rudder defl = 30 deg
wing CL = 1.2
lift = 200 lbs
q = 0.16 psi = 1104 Pa
V = 95 mph = 42.5 m/s
Flap hinge
In a message dated 2/16/2006 11:38:04 P.M. Eastern Standard Time,
[EMAIL PROTECTED] writes:
Some may say I am a weight weenie. I say I am an engineer who knows how to
trim out excesses and still keep the product reliable.
Well, since YOU are the one who replaced your steel rods with CF of
Most(?) engineering solutions retain the integrity of the systems that are
modified to achieve secondary goals. Increasing the series-resistance by
reducing the number of PWR/GND leads to the wing servos was taking a step
backwards. This shows up during launch...
In a message dated 2/16/2006
: [RCSE] Carbon Supra #48 flies - weight 61 oz !
Most(?) engineering solutions retain the integrity of the systems that are
modified to achieve secondary goals. Increasing the series-resistance by
reducing the number of PWR/GND leads to the wing servos was taking a step
backwards. This shows up
PROTECTED]
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
...
Well, since YOU are the one who replaced your steel rods with CF of the
SAME
SIZE(!!) and then stood in amazement (mumbling something about carbon is
supposed to be stronger than steel?) when your stabs blew off
] Carbon Supra #48 flies - weight 61 oz !
Most(?) engineering solutions retain the integrity of the systems that are
modified to achieve secondary goals. Increasing the series-resistance by
reducing the number of PWR/GND leads to the wing servos was taking a step
backwards. This shows up during
overweight that it would not be competitive.
don
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
Most(?) engineering solutions retain the integrity of the systems that are
modified to achieve secondary goals
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
Most(?) engineering solutions retain the integrity of the systems that are
modified to achieve secondary goals. Increasing the series-resistance
OK, my biggest bang for the buck is 5 cell and digitals. I can give up
the dedicated power since it cost me weight in airframe weight as well
as weight extending out the wing.
Now if we can just get battery mfg to do 20 guage battery packs.
Sounds like Don's tradeoff is a good one in
Don't assume windy conditions...we are talking regular early AM no-wind
launches where blow-back was significant enough to reduce time-in-the-air. It's
interesting after a number of monotonous launches utilizing an ALTI to see
graphed sink rates start to line up...
It could be debated (no one
Assuming that the servo power is just at the margin where blowback will
be significant. If it's not, then the extra wire is just extra weight.
[EMAIL PROTECTED] wrote:
Don't assume windy conditions...we are talking regular early AM no-wind
launches where blow-back was significant enough to
I think the best is to use servos that are powerful enough for the
loads and use wire big enough to keep voltage drop to an acceptable
level with maximum current draw on the servos.
What is the maximum current draw of the most popular servos in these planes?
michael N6CHV
On 2/17/06, Michael
17, 2006 9:25 AM
Subject: RE: [RCSE] Carbon Supra #48 flies - weight 61 oz !
With age comes wisdom... :):)
(you didn't explain that this occurred almost 18 years ago...and yes at
that
time I was a tenured faculty in structural mechanics. If you don't break
things, you also don't learn
Sent: Friday, February 17, 2006 3:04 PM
Subject: Re: [RCSE] Carbon Supra #48 flies - weight 61 oz !
I think the best is to use servos that are powerful enough for the
loads and use wire big enough to keep voltage drop to an acceptable
level with maximum current draw on the servos.
What
My table lists 20ga wire as having a resistance of 10.128 ohms per
1000 feet so that is 0.1 ohm for 10 feet.
Ten feet of wire is a servo that is 5 feet (length of the wire) from
the battery.
Ten amps would make a voltage drop of 1 volt and that would be the max
I would want to see even using a 6
I think I got off by a power of ten so things are not as bad as my
numbers make it but the idea of checking to see what is really needed
so I can use enough wire without just throwing more wire at it is
sound.
Anybody know the full stall current draw of the popular servos?
michael
On 2/17/06,
Hi Michael,
you might like to take a look at:
http://www.teaser.fr/~osegouin/aeromode/servos.phtml
The program is in french but looking at the screenshot it seems
pretty straight forward.
The data includes courant maximal which should give you the info
you need.
I'll add the observation
For pictures go the Supra build thread and work your way towards the end
(page 8 and 9).
I forgot to add the link to the thread on RC Groups
http://www.rcgroups.com/forums/showthread.php?t=429879
don
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