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I am getting a Kolb MK III!!
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jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Fri Nov 02, 2007 9:36 am Post subject: Re: I am getting a Kolb MK III!!

You can leave the plane in its normal sitting on the ground attitude but you should use a plumb bob or other weight on a string to measure the location along the tape measure from the nose.



A bathroom scale from the main tires is probably ok for the main gear since they are reasonably accurate around the 200lb area but the tail will need more accuracy since the weight on the tailwheel is much less...probably a digital scale will work fine for the tail wheel.



The entire balance process is empty so you will also have to measure the location of the variables like pilot and fuel and use your estimated weight for each.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

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jindoguy(at)gmail.com
Guest

Posted: Fri Nov 02, 2007 10:45 am Post subject: I am getting a Kolb MK III!!

Grant, Are you a member of your local EAA chapter? You might be able to borrow or rent scales there if you were a member. Does you aircraft come with the plans, both the instructions and the drawings? Weight and Balance info is in the drawings, page 16, if I remember correctly. 

You have to set the tail up to get a 9 degree angle on the bottom surface of the wing. If you have never done a weight and balance, get some help from someone who has done it for the first one. The datum on the Mk III is the leading edge of the wing, hence some numbers will be negative and failure to handle these correctly will make junk of your calculations.  

Personally, I recommend creating your own datum somewhere out in front of the aircraft so that all numbers are positive. This is a bit more work the first time, since you have to reestablish all the locations, however it eliminates the possibility of making an error in calculation. JMHO 



Rick



On 11/2/07, Bob Noyer <a58r(at)verizon.net (a58r(at)verizon.net)> wrote:[quote] Lots of W&B info in Archives.



   regards,

Bob N.    FireFly 070 Old Kolb

http://www.angelfire.com/rpg/ronoy/ 

do not archive



 



 [quote][b]  http://www.matronics.com/Navigator?Kolb-List http://forums.matronics.com  [quote][b]

George Alexander

Joined: 10 Jan 2006
Posts: 245
Location: SW Florida

Posted: Fri Nov 02, 2007 11:24 am Post subject: Re: I am getting a Kolb MK III!!

 	  jb92563 wrote: 	
		  You can leave the plane in its normal sitting on the ground attitude .......<<<<SNIP>>>> 	




Ray of Riverside:



My assumption is that you were including both measuring the ARMs and weighing the plane in the above statement.....



The W&B should be done with the aircraft in the level flight configuration.  (With a Firestar that's about 9 deg angle of attack as measured on the bottom surface of the wing or 7.5" up from level at leading edge of wing).  



In response to Cristal's subject:  "Help with level flight attitude for Mark II",  Possums posted an image that shows the correct set up for a Firestar.  Don't know what the correct AOA would be for a MK III.  



Since most of the empty weight in any Kolb is aft of the mains, probably makes a measurable difference.  I haven't done it, but try weighing just the tail wheel both ways.  Probably several pounds difference resulting in an error for the empty CG (indicating further aft than actual) if you use the weight sitting on the ground.



My .02 worth.

_________________
George Alexander
FS II R503
E-LSA N709FS
http://www.oh2fly.net

pj.ladd(at)btinternet.com
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Posted: Fri Nov 02, 2007 1:59 pm Post subject: I am getting a Kolb MK III!!

You can leave the plane in its normal sitting on the ground attitude >>



You are asking for trouble if you do.  The plane MUST be in flying position.



Cheers



Pat

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Fri Nov 02, 2007 2:40 pm Post subject: Re: I am getting a Kolb MK III!!

The attitude of the aircraft makes no difference in calculating the CG due to the nature of the math, but it does make the measurements more critical.



Thats why you would need a pedulum/plumb bob to get the exact measure.



(Case in point:  Does your planes CG move aft when you are climbing...as the angle is increased similar to what it looks like when sitting on the ground?....NO it does not, or if it did then aft CG aircraft would be spinning/crashing when initiating a climb attitude)



If you put the aircraft in the normal flight attitude granted the measurements become less critical, but still use a plumb bob and accurate scales for the tail especially anyway.



More accuracy the better. So use what ever method you are comfortable with.



If you need proof of the whole concept I will work out a sample with a more extreme ground angle like my Ultrastar, and prove the calculations work out to the same answer in either attitude.



I need to do the weight and balance soon anyway.



As a matter of fact you can even use one scale and put it under each tire one at a time and take a reading, but you would want a very accurate scale if using this method. Concept there being that gravity is constant in your garage or hanger so if you keep the attitude fixed (put a block of wood under the other tire matching the scales thickness and the tail as well) then your plane will weight the same as it does in any fixed attitude and produce exactly the same CG.



You could also use the "hang the plane from the rafters till its level" method  to find the CG if you still feel like a giant scale modeler

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Fri Nov 02, 2007 2:46 pm Post subject: Re: I am getting a Kolb MK III!!

George: In parked attitude ....True the tail would be heavier but you forgot that the weight on the mains would be less...hence the calculation balances out again.



In flight attitude the mains would weight more and the tail would weigh less.



See how these two attitudes cancel the differences out by the math?



Therefore it makes no difference.



Perhaps I need to illustrate with an example.



I guess you should do what you know but if you understand the theory you will realize the truth.....and the Truth will set you free.....right?

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

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d-m-hague(at)comcast.net
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Posted: Fri Nov 02, 2007 3:41 pm Post subject: I am getting a Kolb MK III!!

At 06:40 PM 11/2/2007, jb92563 wrote:

 	  Quote: 	
		  The attitude of the aircraft makes no difference in calculating the CG due 

to the nature of the math, but it does make the measurements more critical.


	


If you measure the weights with the plane not in flying attitude, you would 

have to take into account the vertical position of the CG to and use 

trigonometry (or a plumb bob) to determine the level flight position.  The 

level flight CG is where the plum bob line intersects the vertical CG 

line.  If you don't know where it is vertically (and I doubt many do), the 

plane MUST be in level flight attitude when weighing.



                                 -Dana



--

--

But do you trust the _government_ with semi-automatic assault rifles?

HShack(at)aol.com
Guest

Posted: Fri Nov 02, 2007 4:31 pm Post subject: I am getting a Kolb MK III!!

In a message dated 11/2/2007 1:37:40 PM Eastern Daylight Time, jb92563(at)yahoo.com writes:

  	  Quote: 	
		  You can leave the plane in its normal sitting on the ground attitude but you should use a plumb bob or other weight on a string to measure the location along the tape measure from the nose. 	


  

  

 I'm pretty sure it must be in flying attitude; ie., bottom of wing (at) 9 degrees.



  

 Howard Shackleford

FS II

SC

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Fri Nov 02, 2007 4:49 pm Post subject: I am getting a Kolb MK III!!

Dug out my ancient AC 43.13 (Chapter 13, Paragraph 342, subsection C), did 

some internet research, and everything I could find shows CG is to be 

determined while working with an aircraft in a level attitude. Perhaps there 

is a good reason for this??? And perhaps you are leading the unwary down a 

primrose path to disaster????



Seems I remember something about the effects of CG while in climbing and 

descent attitudes, and the additional problems caused by being out of 

envelope in such a state. I really think you ought to let this go.



Richard Pike

MKIII N420P (420ldPoops)



---

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

ElleryWeld(at)aol.com
Guest

Posted: Fri Nov 02, 2007 6:41 pm Post subject: I am getting a Kolb MK III!!

Ray

  the correct way to do a weight and balance is to put the airplane in its flying attitude it will change the weights and measurments maybe enough to put a plane out of CG if close  a tail heavy airplane will only stall once and will never fly again without a lot of work 

 You can do it any way you want  and I dont want to fly your plane 

  

 Just  what its worth 

  

 Ellery in Maine 

 do not archive





  [quote][b]

Steve Boetto

Joined: 11 Jan 2006
Posts: 365

Posted: Sat Nov 03, 2007 4:34 am Post subject: I am getting a Kolb MK III!!

Look Ma, No Hands

  

  

  

              

  



  

 Steve  B

Firefly 007/Floats

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pj.ladd(at)btinternet.com
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Posted: Sat Nov 03, 2007 6:46 am Post subject: I am getting a Kolb MK III!!

See how these two attitudes cancel the differences out by the math?>>



Whoa!  If you want to find the total WEIGHTt of the plane that will do fine. 

If you are calculating the BALANCE you will be in trouble.



Thats why it is called `weight and balance`



Cheers



Pat

travis(at)tnkolbaircraft.
Guest

Posted: Mon Nov 05, 2007 8:06 am Post subject: I am getting a Kolb MK III!!

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