Matronics Email Lists :: View topic - Model II Weight and Balance

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Model II Weight and Balance

Matronics Email Lists Forum Index -> Kitfox-List

View previous topic :: View next topic

Author Message

Ken Potter

Joined: 18 Aug 2007
Posts: 85
Location: Lanark, Ontario

Posted: Sun Aug 01, 2010 4:07 am Post subject: Model II Weight and Balance

Hi Folks;

I weighed and my plane yesterday and did the W&B calculation.  The forward CG is ok, but the aft CG (at full load) is .3" outside the limit.  Question, how sensitive is the KF to aft CG conditions.  To trim this small amount out and reweigh will be a real pain.



Cheers

Ken

_________________
Ken Potter
Model II, No. 483
Rotax 582, C-Box,
99% Complete
C-FJKP
Lanark, Ontario

poasttown(at)yahoo.com
Guest

Posted: Sun Aug 01, 2010 4:51 am Post subject: Model II Weight and Balance

Ken

  

 I'm not sure this is an answer to your question but when I finished my model four back in 1996, with a Rotax 582, I had to add five piunds of lead shot up against the firewall to get my W&B correct.  Since then I have changed to a Jabiru 2200 and I removed the lead shot.

  

 Mike Chaney



--- On Sun, 8/1/10, Ken Potter <kjpotter(at)sympatico.ca> wrote:



  	  Quote: 	
		  

From: Ken Potter <kjpotter(at)sympatico.ca>

Subject: Model II Weight and Balance

To: kitfox-list(at)matronics.com

Date: Sunday, August 1, 2010, 8:08 AM



 --> Kitfox-List message posted by: "Ken Potter" <kjpotter(at)sympatico.ca (kjpotter(at)sympatico.ca)>



Hi Folks;

I weighed and my plane yesterday and did the W&B calculation.  The forward CG is ok, but the aft CG (at full load) is .3" outside the limit.  Question, how sensitive is the KF to aft CG conditions.  To trim this small amount out and reweigh will be a real pain.



Cheers

Ken



--------

Ken Potter

Model II, No. 483

Rotax 582, C-Box, 

99% Complete

C-FJKP 

Lanark, Ontario





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=307024#30702om/Navigator?Kitfox-List" target=_blank>http://www.matronics.com/Navigatosp;              - MATRONICS WEB FO/" ;               -Matt Dralle, List Admin==========





	


                [quote][b]

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Aug 01, 2010 5:07 am Post subject: Re: Model II Weight and Balance

Ken ,

I would re-weigh --  and re-check numbers again.



Some Kitfox had the c o G range extended AFT but I not sure what model. 



Is your numbers are accurate as well as your scales ?



.3 is not alot and what was it solo? 



What weights did you use for persons?  170 or actual ?



You must not have a dash tank?   The dash tank would help this alot

_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube

Ken Potter

Joined: 18 Aug 2007
Posts: 85
Location: Lanark, Ontario

Posted: Sun Aug 01, 2010 5:48 am Post subject: Re: Model II Weight and Balance

Dave,



The scales I used belong to EAA chapter 245 in Ottawa and are relatively new.  I checked them with a test weight and they were + - 1 lb.

My plane is one of the later model II's with the 1.5 gal tank behind the seat. The battery is mounted forward on the rear side of the firewall.  The only piece of equipment not on board was my Garmin 296 GPS but that is mounted right under the datum line anyways.

One thing I didn't mention is that the plane has come out relatively heavy at 550 lbs empty, probably from my full polyfibre paint treatment. 



As per the instructions in the original Denny manual for full gross weight aft CG calculation, I used me in the pilot seat and weights in the pax seat to bring it up to gross of 950. That's the calculation which came out as .3" aft of limit.  The pilot only (fwd CG) came out well within limits.  



I'm going to re-crunch the numbers this morning just to double check the calculations.  If I need weight forward I'll just install a larger battery. Better to have that weight providing some benefit.

Cheers

Ken

_________________
Ken Potter
Model II, No. 483
Rotax 582, C-Box,
99% Complete
C-FJKP
Lanark, Ontario

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Sun Aug 01, 2010 6:57 am Post subject: Re: Model II Weight and Balance

Pat, work up one weight and balance sheet with a loading that puts the CG right at the aft limit and another that puts it at the forward limit.  Keep these in the plane to show if asked at a ramp check.



Adding weight to stay within the CG limits is productive only if it allows the payload to increase too.

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Aug 01, 2010 7:07 am Post subject: Re: Model II Weight and Balance

Ken,



Do you have a excel sheet that you can input numbers on ? 



Reason I ask is that did you actually measure everything or did you use someone else's numbers. 



550 lbs is heavy for a model 2 ------ 



I would bet that you will be ok flying it.

Ken Potter

Joined: 18 Aug 2007
Posts: 85
Location: Lanark, Ontario

Posted: Sun Aug 01, 2010 7:18 am Post subject: Re: Model II Weight and Balance

Dave,



I measured the main gear moment  (2.375") and the tail wheel moment myself on the actual A/C.  I'm going out to re-measure again as I trust the scales and think that a miss-measurment, especially of the tailwheel moment could have given me the .5 inch out of limit in the full gross state. 



I have excel but I've also rechecked my calculations, and other than one small mistake, they check out.   The only other thing I can think of is that I did the full gross calcuation with the behind-the-seat fuel tank full.... but then, that tank is full when in flight anyways so in my mind should be included.

Cheers

Ken

_________________
Ken Potter
Model II, No. 483
Rotax 582, C-Box,
99% Complete
C-FJKP
Lanark, Ontario

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Aug 01, 2010 7:48 am Post subject: Re: Model II Weight and Balance

KEn, I hope these numbers might help you but this is for my IV  model



Notice my Empty weight was for before the last paint job but still light and great performer.  It makes me wonder where some Kitfox get so heavy but you can see why their performance sucks.



http://www.youtube.com/user/kitfoxflyer

Skystar Kitfox Model IV ( 4) ser. #1717  C-FDUG											

WEIGHT AND BALANCE FOR AIRCRAFT  Wheels  orig copy Installed 											

											

THE DATUM : Leading Edge of wing                                                              											

Leveling Means: Bubble level on longitudinal fuselage floor tubing below the cabin											

Maximum Gross Weight:1050 											

Forward CG limit   11.37     Aft CG limit 16.00											

									

ALL WEIGHTS IN LBS, DISTANCES IN INCHES and AFT (unless marked "-")											

PART ONE											

(EMPTY WEIGHT DATA)											

IF YOU DON'T KNOW, GO TO PART TWO											

ENTER  EMPTY AIRCRAFT WEIGHT HERE =	520	LBS									

ENTER AIRCRAFT EMPTY CG HERE =	12.95	IN.									

ENTER EMPTY MOMENT HERE = 	6734	INCH/LBS									

CALCULATED EMPTY AIRCRAFT MOMENT = 	6734	INCH/LBS									

											

PART TWO											

(CALCULATING EMPTY WEIGHT DATA)											

FIGURING EMPTY WEIGHT CG.											

MAIN WHEELS DATA	WEIGHTS										

RIGHT MAIN WHEEL WEIGHT = 	244	LBS									

LEFT MAIN WHEEL WEIGHT = 	242	LBS									

MAIN WHEEL DISTANCE FROM DATUM = 	2.9	IN.									

MAIN WHEEL MOMENT = 	1409.4	INCH/LBS									

CALCULATED MAIN WHEEL MOMENT = 	1409.4	INCH/LBS									

											

TAIL WHEEL/NOSE WHEEL DATA											

TAIL/NOSE WHEEL WEIGHT = 	34	LBS									

NOSE WHEEL DISTANCE FROM DATUM=	156.6	IN.									

NOSE MOMENT IF KNOWN = 		INCH/LBS									

CALCULATED TAIL/NOSE MOMENT = 	5324.4	INCH/LBS									

											

TOTAL WEIGHT = 	520	LBS									

	CG		MOMENT								

EMPTY WEIGHT CENTER OF GRAVITY DATA	12.95	IN	6734	INCH/LBS		AFT of datum					

											

FIGURE FINAL CG BELOW											

ENTER THE FOLLOWING AS NEEDED											

SUBJECT	WEIGHT	X	ARM	X	MOMENT						

AIRCRAFT EMPTY WEIGHT = 	520	X	13.29	X	6884.22	INCH/LBS					

PILOT WEIGHT = 	170	X	18.3	X	3111	INCH/LBS					

PASSENGER WEIGHT = 	170	X	18.3	X	3111	INCH/LBS					

FUEL WEIGHT (7.2 LBS/GAL) = 	56	X	-8	X	-448	INCH/LBS					

OIL WEIGHT (1.9LBS/QT) = 	3.8	X	-21	X	-79.8	INCH/LBS					

BAGGAGE WEIGHT = 		X	30	X	0	INCH/LBS					

Wing tanks    (7.2 LBS/GAL)  	72	X	16.5	X	1188	INCH/LBS					

ELT	3.3	X	0	X	0	INCH/LBS					

First Aid Kit	1.5		30								

		X		X	0	INCH/LBS					

											

TOTALS	996.6	LBS			13766.42	INCH/LBS					

											

AIRCRAFT CENTER OF GRAVITY =	13.81	INCHES Aft of DATUM									

											

											

Equipment list  included in Weight and Balance report  as required by  CARS 549.13  Equipment and Instruments                                 											

Additional Equipment  List: 											

ELT, First aid kit  Added to Weight and Balance report											

											

MAINTENANCE SCHEDULE STATEMENT											

The described maintenance has been performed in accordance with the applicable airworthiness requirements											

											

Date:_______________											

											

____________________________________											

(Signature)

akflyer

Joined: 07 May 2007
Posts: 574
Location: Soldotna AK

Posted: Sun Aug 01, 2010 8:09 am Post subject: Re: Model II Weight and Balance

if it is anything like the Avid, the CG range is very conservative.  Dean Wilson told me that I could safely go back to 19" or so, and it would fly better.  He said not to stall it at more than 20" without using flaps or I may never get the nose back down in time.



I flew mine at 18" and the performance was much better.  No running out of elevator in the flair.  Slow flight and STOL was much better at 18" versus the more forward CG mine comes in at empty.

_________________
DO NOT ARCHIVE
Leonard Perry aka SNAKE
Soldotna AK
Avid "C" / Mk IV
582 (147 hrs and counting on the rebuild)
IVO IFA
Full Lotus 1450
#1 snake oil salesman since 1-22-2009

I would rather die trying to live, than to live trying not to die....

Tom Jones

Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA

Posted: Sun Aug 01, 2010 8:54 am Post subject: Re: Model II Weight and Balance

Pat, just to be sure you didn't forget it. Did you remember to subtract the tare weight from the tail wheel weight?

_________________
Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
Ellensburg, WA

MichaelGibbs(at)cox.net
Guest

Posted: Sun Aug 01, 2010 9:20 am Post subject: Model II Weight and Balance

Ken sez:



 	  Quote: 	
		  I weighed and my plane yesterday and did the W&B calculation.  The 

forward CG is ok, but the aft CG (at full load) is .3" outside the 

limit.


	


How did you accomplish a "full load"?  Did you have weight in the 

baggage area to reach "full"?  This might just indicate that you 

cannot have that much behind the seats when operating at higher 

weights in the real world.



If, on the other hand, you only had weight in the seats and the CG 

moves past the aft limit before reaching maximum gross weight, you 

may have to resort to adding ballast.



Mike G.

N728KF, Kitfox IV-1200 Speedster

Phoenix, AZ

Ken Potter

Joined: 18 Aug 2007
Posts: 85
Location: Lanark, Ontario

Posted: Mon Aug 02, 2010 7:57 am Post subject: Re: Model II Weight and Balance

Thanks everyone for your help on this one.  I re-weighed the plane and it came in almost exactly as before for empty weight.   When I re-measured the tail wheel moment I discovered that I had measured 1 1/2" to long.  After re-running the calculation it is now just under the max aft CG at max gross of 950 lb. 



Because the plane is 25lb heavy I guess I'll have to lose weight myself to compensate.  

Cheers



Ken

_________________
Ken Potter
Model II, No. 483
Rotax 582, C-Box,
99% Complete
C-FJKP
Lanark, Ontario

msm_9949(at)yahoo.com
Guest

Posted: Mon Aug 02, 2010 9:29 am Post subject: Model II Weight and Balance

Ken,

  

 My Model 2 came in at a "heavy" 535 lbs empty. (alot of shiny Aerothane aboard). Since doing W&B I've added a cargo pod and other gear that brings it up to about 550.  With myself and full fuel (13 US gal) there's still enough left for a 170 lb passenger. It flies great, especially solo. 

  

 Marco Menezes N99KX

 Model 2 582-90 C Box 3:1 w/clutch

  

 



--- On Mon, 8/2/10, Ken Potter <kjpotter(at)sympatico.ca> wrote:



  	  Quote: 	
		  

From: Ken Potter <kjpotter(at)sympatico.ca>

Subject: Re: Model II Weight and Balance

To: kitfox-list(at)matronics.com

Date: Monday, August 2, 2010, 11:57 AM



 --> Kitfox-List message posted by: "Ken Potter" <kjpotter(at)sympatico.ca (kjpotter(at)sympatico.ca)>



Thanks everyone for your help on this one.  I re-weighed the plane and it came in almost exactly as before for empty weight.   When I re-measured the tail wheel moment I discovered that I had measured 1 1/2" to long.  After re-running the calculation it is now just under the max aft CG at max gross of 950 lb. 



Because the plane is 25lb heavy I guess I'll have to lose weight myself to compensate.  

Cheers



Ken



--------

Ken Potter

Model II, No. 483

Rotax 582, C-Box, 

99% Complete

C-FJKP 

Lanark, Ontario





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=307191#30719om/Navigator?Kitfox-List" target=_blank>http://www.matronics.com/Navigatosp;              - MATRONICS WEB FO/" ;               -Matt Dralle, List Admin==========





	


               [quote][b]

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Aug 03, 2010 10:39 am Post subject: Model II Weight and Balance

The last line is only for certified aircraft.  



Noel

--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Aug 03, 2010 1:50 pm Post subject: Re: Model II Weight and Balance

 	  Float Flyr wrote: 	
		  The last line is only for certified aircraft.  



Noel

-- 	




Noel you are wrong. 



Mine is registered as Amateur built that is what is req'd in Canada



>>Equipment list  included in Weight and Balance report  as required by  CARS

549.13  Equipment and Instruments



Additional Equipment  List:



ELT, First aid kit  Added to Weight and Balance report



MAINTENANCE SCHEDULE STATEMENT



The described maintenance has been performed in accordance with the

applicable airworthiness requirements



Date:_______________



____________________________________



(Signature)

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Sun Aug 08, 2010 7:44 am Post subject: Model II Weight and Balance

In that case you won't be able to fly it in Canada unless it is signed off

by a certified AME. (Not one would sign it.) That is a release statement

which says that the plane is kept to "Applicable airworthiness standards.

No Amateur plane built, by definition, meets those standards.



The statement, in Canada, also means any part on the plane can be traced

back to the manufacturer as a certified part.  Can you say that for every

nut and bolt on your plane?  No.  Good, it means you are flying amateur

built .



BTW At one time if you put a certified engine in your plane it is supposed

to have the serial number modified to make it uncertified.  This is still

done when transferring a plane from Certified to Owner Maintained category.

I'm not sure if it is still to be done on Amateur category. 



The log book of my 'Fox had the maintenance signed off by the original

owner/builder and also lists his pilot number.  The words, "Applicable

Airworthiness Standards" doesn't appear in my logs at all.



Noel



--

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Display posts from previous:

	Matronics Email Lists Forum Index -> Kitfox-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum