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RV-7 & RV-7A Weight & Balance Calc. Tool

walter

walter

Well Known Member
For those of you who have not yet done so, or need to re-calc your W&B, I modified a calculator to accomodate 7 and 7A variants. It graphically displays your takeoff and landing cg parameters and a bunch of other items. If you have weighed your nose/tail and mains you plug those numbers, it will use Vans moment arms to tell you what your cg is. Neat for playing what-if scenarios. Of course, the usual disclaimer should be issued about using this for flight purposes. Don't trust me, trust you.

Feel free to download or use online.

http://rv7-a.com/n447rv_documents.htm
 
Walter, thanks for the W/B calculator. The graph feature is great. My knowledge of Excel is quite thin beyond pure numbers crunching.

dd
 
Very Nice - Sample Weights Anyone?

Very nicely done!

I don't have a plane yet so I am playing with the calculator at this point.

Do we have some typical or untypical data for the three gear weights on a 7A? I just plugged in some values to get to a typical empty weight of about 1100 pounds but I don't know how that 1100 pounds is typically distributed between the gear.
 
How far off are Vans ARMS??

I just re-weighed my RV7 I bought flying and I think the previous builder was off.

Builder Data
right wheel- 475lbs at 66.5"
left wheel- 476lbs at 66.5"
tail wheel- 77lbs at 250.25"
total wt- 1028lbs
empty CG- 80.26

My Data
right wheel- 509lbs at 66.5"
left wheel- 519lbs at 66.5"
tail wheel- 73lbs at 250.25"
total wt- 1101 lbs
empty CG- 78.7" (a smidge less than least aft datum)

VANS Example Numbers:
right wheel- 509lbs at 69.25
left wheel- 519lbs at 69.25"
tailwheel- 73lbs at 249.25
total wt- 1101
empty CG- 81.18"

This puts me in the middle of CG EMPTY :(
(O-320, Sense FP, paint, interior)

Prior to this W&B, I have felt the plane is slight AFT CG, making it tough to get it slowed down on final with the proper nose down attitude.

I used brand new calibrated airplane scales, so the wt seems reasonable. How about the ARMS?? How far off were folks from Vans #'s

Thanks
 
Wow-Forward CG with low fuel and only pilot

Walter, nice job on the spreadsheet. I also would like to know the -7A wheel weights. It sure seems that the -7A can get nose heavy with my heavy rear end in the pilot seat. I'll have to increase the mileage I'm running to loose some more weight. :eek:
 
Calculator

Walter
Would it be possible to make an excel program to calculate the nose wheel weight using our individual plane weight numbers rather than Vans for the SB they put out a few weeks ago for the A models.
Gerry
 
Not sure if I understand your question. Wheel weights can only be accurately be determined by weighing with scales. I'm probably misreading your question?
 
Heavy person = aft CG

skatetrainer said:
Walter, nice job on the spreadsheet. I also would like to know the -7A wheel weights. It sure seems that the -7A can get nose heavy with my heavy rear end in the pilot seat. I'll have to increase the mileage I'm running to loose some more weight. :eek:
Click to expand...
I think that everything except fuel is aft of the pivot point.
 
W&B spreadsheet with nose wheel weight

Gerald Clabots said:
Walter
Would it be possible to make an excel program to calculate the nose wheel weight using our individual plane weight numbers rather than Vans for the SB they put out a few weeks ago for the A models.
Gerry
Click to expand...

Gerry... I modified my previous RV-6A spreadsheet (with the nose wheel weight calculations) into a RV-7A one....

Your plane numbers go in the green boxes, loading numbers for calculation go in yellow boxes.

I think this is what you are asking for... try it out....

http://home.earthlink.net/~gilalex/RV/wb-RV-7A.xls

gil A
 
az_gila said:
... I modified my previous RV-6A spreadsheet (with the nose wheel weight calculations) into a RV-7A one....
Click to expand...

Gil- Is the datum point different on a -7A than on a -6A? I have a -6A, and the builder (not me) shows the datum at 60" ahead of the wing LE, with an allowable CG range of 68.7 to 76.8. Trying to use your spreadsheet w/o much luck, altho I admit that I'm severely "spreadsheet challenged.":eek:

EDIT: Partially answered my own question. Van's Web site has W&B info for each model, and the -7 series has a 70" datum. Still trying to figure out how to use your spreadsheet with the -6 series. THANKS
 
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For the -6A

PCHunt said:
Gil- Is the datum point different on a -7A than on a -6A? I have a -6A, and the builder (not me) shows the datum at 60" ahead of the wing LE, with an allowable CG range of 68.7 to 76.8. Trying to use your spreadsheet w/o much luck, altho I admit that I'm severely "spreadsheet challenged.":eek:

EDIT: Partially answered my own question. Van's Web site has W&B info for each model, and the -7 series has a 70" datum. Still trying to figure out how to use your spreadsheet with the -6 series. THANKS
Click to expand...

Pete... if you are talking about a -6A, then use this one.....:)

http://home.earthlink.net/~gilalex/RV/wb-RV-6A.xls

Yes.. apparently the datum did move....

NOTE... the co-pilot got ejected in flight in the original version...(software oops!) ...it's now fixed as of 8:00 am MST, 11-23-07... please re-download the file if you have an earlier copy...
gil A
 
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How to..

I have a nice spreadsheet I picked up somewhere for a 7A but not sure how to post it as a link on the web, is there a quick tutorial on this somewhere?
 
Walt said:
I have a nice spreadsheet I picked up somewhere for a 7A but not sure how to post it as a link on the web, is there a quick tutorial on this somewhere?
Click to expand...
So you have it on the web already? If so, just write here the address where it is and it will be formatted as link... :confused:
 
RV4

Walter

I was good of you to do these sheets......... but there appears to be something wrong with the RV4 sheet. The graph does not show the correct c of G range for a 4, and I think the bagage limit you specify is wrong.
 
walter said:
For those of you who have not yet done so, or need to re-calc your W&B, I modified a calculator to accomodate 7 and 7A variants. It graphically displays your takeoff and landing cg parameters and a bunch of other items. If you have weighed your nose/tail and mains you plug those numbers, it will use Vans moment arms to tell you what your cg is. Neat for playing what-if scenarios. Of course, the usual disclaimer should be issued about using this for flight purposes. Don't trust me, trust you.

Feel free to download or use online.

http://rv7-a.com/n447rv_documents.htm
Click to expand...

Good evening
I can't open it , Yvon
 
Hi Gil
I hope to fly my RV6A later this month for the first time and need to do the W&B. I have tried to open the fist post and your website for this sheet but no success. Could you email me your format if you don't mind me using it.
Kind Regards
[email protected]
Enjoy your input on this forum.
 
Larry Ocker said:
Make sure you measure YOUR axel centers from the datum. My 7A was different than Vans numbers.
Larry
N200LL
Flying
Click to expand...

+1. It was not much off, but it did make a difference in CG numbers and nosegear loading at dif CG locations.
 
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