REFLECTOR: Gross weights

steve korney s_korney at hotmail.com
Sat Jun 24 12:42:35 CDT 2006


Snip

"You are correct in that at a lower wt the wing can handle a higher g 
loading.  However, this is my take on the subject:

1) Load factors on other aircraft components (engine mounts, avionics boxes, 
etc) are designed around the maneuver speed load factor (Nmax at a heavy 
weight). So although the wing can handle higher gs at lower weights, other 
components can not.  This is why maneuvering speed limits you in terms of g 
loading, not total load (lbs).  Only at max wt does it limit your total 
load.

Refer to FAR 23.371 and 23.423.

2) The definition of VA (maneuvering speed)is that it does not allow you to 
exceed a certain G-LEVEL.  Yes, it so happens that at the max weight and 
above this g-level structural failure will result(just another reason not to 
exceed VA).  But the bottom line is the definition is what it is: its a 
'g-level' definition.

3) There is nothing on an airplane that will tell you what your maximum lift 
is (we're talking the good old days now - not the new technology stuff.  
Remember, these defintions and terms were created long ago).  So there is no 
way that a pilot can know when the maximum load is exceeded.  But, a simple 
accelerometer can be used for this purpose.  And if the pilot never exceeds 
Nmax (regardless of weight), then he will never overload the aircraft.  In 
fact at light weights, he will have healthy safety margins (this is a good 
thing)."

Best... Steve



----Original Message Follows----
From: Scott Derrick <scott at tnstaafl.net>
Reply-To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: Gross weights
Date: Sat, 24 Jun 2006 07:37:00 -0600

  >>I agree with Steve K., adding extra weight "eats" into the loading
strength safety factor - in other words, advise caution on high speeds
in turb conditions.

This sounds odd(wrong) to me..    For any airplane you reduce
Maneuvering (Va) speed if you are light. The speed for Va given in most
POH's is for gross weight and you reduce that speed the lighter you
are.  It would seem logical to me that Va would be reduced even further
the heavier you were?

So unless somebody can  show me the beef , I  will continue to fly under
the understanding that the heavier I am the safer I am as far as
turbulence is concerned(at the same speed)..  An added benefit to being
heavy is you also get a  smoother ride in turbulence.

Now I will agree that the heavier you are requires a softer landing.
Three of the requirements to increasing my gross is to upgrade the nose
gear including the new XL type bushings, add additional carbon torsional
wraps to the main gear and upgrade the brakes.

Scott D.

Scott Baker wrote:
 > I have flown the factory 173FG (200hp) up to 2900 pounds (sea level,
 > 80-degrees) doing some heavy lifting studies for a customer - the
 > aircraft lifted off within 2000' and sustained a climb rate of 400 to
 > 500 fpm - finally got it to 10,000' - aircraft handled well, just
 > lacking climb performance with the 200hp.  I agree with Steve K.,
 > adding extra weight "eats" into the loading strength safety factor -
 > in other words, advise caution on high speeds in turb conditions.
 > SB
 >
 >     ----- Original Message -----
 >     *From:* NMFlyer1 at aol.com <mailto:NMFlyer1 at aol.com>
 >     *To:* reflector at tvbf.org <mailto:reflector at tvbf.org>
 >     *Sent:* Saturday, June 24, 2006 1:02 AM
 >     *Subject:* REFLECTOR: Gross weights
 >
 >     Seemed like a good time to ask this question with all the W&B
 >     questions.
 >
 >     I have a 173 FGE. Empty weight is supposed to be between 1250 and
 >     1400 LBS. With what I have done installing the aluminum 4.3L
 >     Chevy, Superfilling all the flying & control surfaces,,, etc.... I
 >     should come in about 1400LBS.
 >
 >     The thing is, I have 340 HP in a 173 for about the same weight as
 >     a 200HP IO-360.
 >     Where do I put my gross weight?  I know Bill Mulrooney put his V8
 >     powered 173RG at 2900lbs with his extra power (and lots of extra
 >     weight). I did get a tad of advice from a factory rep. I was told
 >     to add up the empty weight of my plane... full fuel... four-200LB
 >     people, and 200 LBS of baggage. Then add 100LBS and use that
 >     number. The reasoning was that my plane will haul almost anything
 >     with the extra HP, and you want to make sure that you are ALWAYS
 >     within W&B on paperwork to satisfy the FAA and insurance toads.
 >
 >     Any input?
 >
 >     Thanks   Kurt
 >
 >     
------------------------------------------------------------------------
 >     _______________________________________________
 >     To change your email address, visit
 >     http://www.tvbf.org/mailman/listinfo/reflector
 >
 >     Visit the gallery!  www.tvbf.org/gallery
 >     user:pw = tvbf:jamaicangoose
 >     Check new archives: www.tvbf.org/pipermail
 >     Check old archives:
 >     http://www.tvbf.org/archives/velocity/maillist.html
 >
 > ------------------------------------------------------------------------
 >
 > _______________________________________________
 > To change your email address, visit 
http://www.tvbf.org/mailman/listinfo/reflector
 >
 > Visit the gallery!  www.tvbf.org/gallery
 > user:pw = tvbf:jamaicangoose
 > Check new archives: www.tvbf.org/pipermail
 > Check old archives: http://www.tvbf.org/archives/velocity/maillist.html

--

-
     Liberty means responsibility. That is why most men dread it.

     George Bernard Shaw, Liberty

_______________________________________________
To change your email address, visit 
http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html




More information about the Reflector mailing list