03 September 2017

First Flight Prep: Weight and Balance.

Update 10-Dec-23: I was able to secure high quality calibrated scales from Weigh-Systems Inc. from a gracious on-field helicopter concern.  This changed my W&B numbers which are updated at the bottom of the page.
 
With the airplane fully assembled, measuring weight and balance was next.  I obtained three of these 660 lb scales, model PCR-3315.  They can be found cheaper elsewhere.

It's important not to lift the airplane up then place it on the scales.  This is because the main gear wheels would then place a lateral force on the scales, skewing the results (not just the scales!).  

So we first lifted the main wheels up onto blocks that were the same height as the scales.  This was easily accomplished by my friend laying on his back and lifting each main wheel with his legs on the wing spar.  I then slipped the wood blocks under each wheel, slightly off-center so that the wheel could slip into place when it bore weight.


Here is the left wheel on the block, chocked.


Next, we put the right wheel on the block, pushed the plane onto the two scales for the mains, then used the engine crane to lift the nose wheel onto its scale. 


Following that, all of the fairings were mounted with the screws.  Headsets, carpets and seats remained in the aircraft.  The engine was full with oil whilst the tanks were dry.

Below are the results, using the arm lengths from the demonstrator (I will update this table whence I measure the arms for my aircraft).  I expected that my airplane would probably be the heaviest RV-14A of the fleet.  I believe I am correct.  This is because my panel is elaborate (weighing nearly 30 pounds), as well as nearly all of the interior aluminum (except for the rudder and fuel tanks) is primed.  I will verify the accuracy, as best I can, of the scales.


Weight Arm Moment
Left 471 97.44" 45,894
Right 472 97.59" 46,062
Nose 369 40.19" 14,830
Total 1,312
106,786
CG 81.4"


You can find my W&B spreadsheet on my POH and checklists page.

As a comparison, I searched for others' results using VAF as well as asking other builders.

Aircraft Owner Model Weight CG Notes
N14YT Tim Olson RV-14A 1,309 81.13 Painted, primed.
VH-XIV Alan Carlisle RV-14A 1,289 80.9 Painted.

E RV-14A 1,280 81.31 Unpainted, primed, second alternator, IO-390C

Cliff RV-14A 1,280 82.29 Unpainted. XP-400, EFII, second battery.
N626KM Bob Meyer RV-14A 1,262 80.3 No fairings, paint. Two batteries & alternators.
N947RV Carl and Rafael RV-14A 1,255 80.24 Unpainted.

TJ RV-14A 1,247 79.94 Unpainted.
N914VA Van's RV-14 1,246 81.38 Painted.
N214VA Van's RV-14A 1,237 80.67 Painted.
N214SW Stoney Ware RV-14 1,230 80.54 Unpainted.
C-FWIY Tom Martin RV-14 1,227
Unpainted.

However, my fat plane's weight doesn't concern me.  I'm a firm believer that the best way to manage aircraft weight is for the pilot to manage his/her weight! 
 
Update 10-Dec-23:  I was able to secure high quality calibrated scales from Weigh-Systems Inc. from a gracious on-field helicopter concern.  Weighing with these scales reduced my BEW (by 39 lbs from 2022 and 32 lbs from 2017) and changed my W&B numbers which are updated below.  The fuel tanks were de-fueled, all loose items from the interior were removed (except for the seats, carpets, side panels and restraint systems) and 6 quarts were in the engine.
 

Weight Arm Moment
Left 456 97.25" 44,346
Right 462 97.75" 45,161
Nose 362 40.25" 14,571
Total 1,280
104,077
CG 81.31"




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