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Twinstar MK II W+ B solved

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lmorgan100(at)charter.net
Guest

Posted: Fri May 25, 2012 1:14 pm Post subject: Twinstar MK II W+ B solved

I finally figured out why my weight and balance was not coming out correct.

I am ashamed to say that I happened to notice a bulge in the tarp that was

over my engine and that bulge turned out to be about two gallons of water

hanging behind the wing. This was making my calculations show a slightly

tail heavy plane, now without the water, I come in at 35% with one person

and at 25% with two people. I could still use something from a Twinstar

manual that states that this is the correct range in case I am asked where I

got the numbers from for my airworthiness certificate.

thanks,

Lee..

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elleryweld(at)aol.com
Guest

Posted: Sat May 26, 2012 4:16 am Post subject: Twinstar MK II W+ B solved

i am Just thinking out loud so you plan to fly the airplane with that plastic on it?  would it be ok to pile a bunch of items on the airplane some where and leave em there during the W&B process" NOT"

    any weight is weight suppose to do a W&B with only what you would normally have on the airplane during flight operations

 

 

     Ellery Batchelder Jr.

 

 

 

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lmorgan100(at)charter.net
Guest

Posted: Sun May 27, 2012 4:37 am Post subject: Twinstar MK II W+ B solved

Ellery,

Your right,

I said I was ashamed, But I am still looking for a copy of the page in the

Twinstar Mk II manual that gives the acceptable CG range.

thanks,

Lee..

          

 

_____________________________________

Time: 05:16:57 AM PST US

Subject: Re: Twinstar MK II W+ B solved

From: Ellery Batchelder Jr <elleryweld(at)aol.com>

i am Just thinking out loud so you plan to fly the airplane with that plast

ic on it?  would it be ok to pile a bunch of items on the airplane some whe

re and leave em there during the W&B process" NOT"

 any weight is weight suppose to do a W&B with only what you would normally

 have on the airplane during flight operations

Ellery Batchelder Jr.

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cristalclear13

Joined: 19 Sep 2007
Posts: 363
Location: Southeast Georgia

Posted: Sun May 27, 2012 8:14 am Post subject: Re: Twinstar MK II W+ B solved

 	  lmorgan100(at)charter.net wrote: 	
		  I finally figured out why my weight and balance was not coming out correct.

I am ashamed to say that I happened to notice a bulge in the tarp that was

over my engine and that bulge turned out to be about two gallons of water

hanging behind the wing. This was making my calculations show a slightly

tail heavy plane, now without the water, I come in at 35% with one person

and at 25% with two people. I could still use something from a Twinstar

manual that states that this is the correct range in case I am asked where I

got the numbers from for my airworthiness certificate.

thanks,

Lee.. 	




Lee, I haven't had time to look up all my original measurements and calculations, but I do recall someone telling me that the CG should be 20-30% of the wing.  My datum was 69.75" forward of the main wheels and so I set my CG at 80-89" aft of the datum.

I'm glad you found your issue.  Let me know if you need any more info.

Sorry for the delay.

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_________________
Cristal Waters
Kolb Mark II Twinstar Rotax 503 DCSI Sept 2007 - sold Sept 2012
Private Pilot Aug 2008
ELSA Repairman for N193Y April 2008
Rotax 2 stroke maintenance April 2009

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun May 27, 2012 9:34 am Post subject: Twinstar MK II W+ B solved

 	  Quote: 	
		   I finally figured out why my weight and balance was not coming out

correct.
	


 

 	  Quote: 	
		   Lee..

  
	




Lee/Kolbers:



In my humble opinion and experience building and flying Kolbs for many

years, problems with getting a Kolb aircraft into a flyable approved cg

range is more paper than airplane.



In the beginning no weight and balance form was used with the 1984

Ultrastar.  Build it close to what the plans called for and it would be

within cg and fly like a bird.  In fact, Homer Kolb said if you wanted to

check the cg, hang the Ultrastar from a rafter with the rope attached at the

main spar carry through of the fuselage.  If it balanced, it was good to go.

I never tried that.



1987 Firestar was built and flown with the same instructions from Homer

Kolb.



1992 MKIII had a weight and balance formula.  Needed it to pass the

airworthiness inspection for homebuilt experimental classification.  We

worked on that problem for quite a while, then gave up and used an "M-1

pencil" to complete the form to make the MKIII flyable.  The numbers kept

saying we had a severe aft cg problem.



One way to demonstrate that I did not have an aft cg problem, I installed

and flew a 12 lb Maule Tundra Tail Wheel on my MKIII.  Did I have an aft cg

problem?  Nope.



Should everyone who builds and flies Kolbs use the same weight and balance

check that I do?  Would not say or recommend one way or the other.  I flew

the MKIII with that 12 lb tail wheel, 150 lbs of fuel and 125 lbs of cargo

behind the cg, for about 5 years.  That includes 5 or 6 flights to the West

Coast and Lakeland, plus a couple to Oshkosh.  I think I am good to go.

Still flying with a 7 lb Maule 6" solid rubber tail wheel.  Works great.



Take care,



john h

mkIII

Titus, Alabama

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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

zeprep251(at)aol.com
Guest

Posted: Sun May 27, 2012 12:32 pm Post subject: Twinstar MK II W+ B solved

You certainly can fly a Kolb relatively safely with it way aft CG wise.But you cannot say it will fly the same as it would if it were in range.All you have to do is try it both ways,preferably in rough air,and you can make your own decision.

G.Aman Mk3 Jabiru 2200A 700 hrs



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flykolb(at)pa.net
Guest

Posted: Sun May 27, 2012 2:42 pm Post subject: Twinstar MK II W+ B solved

I found the following in the archives.  It may or may not help for what you

are looking for, but it was the determination way back then.

Dennis

To Kolb Builders,



When we installed the 912 we simply added some weight (about (20 lb.) in the

nose and went flying.  We then started removing the weight gradually and

wound up eventually removing it all.  We thus wound up with a C.G. at 40%

with our flight instructor (who weighs about 170 lb.).  To our amazement the

Mark-III still stalls fairly well.  This is how we are currently flying our

own Mark-III.



The Mark-III has been certified in England and they tested the C.G. as far

back as 39% and found that it still had adequate stall characteristics.



At 35-37%, all Kolb aircraft have good stall characteristics.



Even though we know the C.G. can be further back than 35%, we will be

officially leaving it at 35%, the margin is to absorb a certain amount of

scale error.



Eventually we will be exploring even more aft C.G. conditions.  Our large

chord wing and large tail volume, would seem to help in handling a more aft

C.G. condition.



If anyone has any further questions on C.G. please feel free to ask.



Sincerely,



Dennis L. Souder

President, Kolb Aircraft

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