Confirm wing lift?

[Spg01]

I just recieved my new wing and I would like to confirm its lift. Would the easiest way be to bring it to a pool and add weight until it sinks? So if I put 40 lbs on a 35 lb wing it should sink?

The reason is that the wing I ordered was supposed to be a 35lb wing but everything on the wing says 40 lbs. I wrote the vendor and they said it was a mislabeled 35, if so why a tag that says 40lb and a box that says 40 lb? So being the trusting person I am I would like to double check the wing and go from there.

 

[fjpatrum]

I just tested mine in the bathtub. Attached it to my plate then started adding weights to it until it didn't float any more.

 

[Rainer]

Get a scale. Fit the wing to a plate. Weigh it. Now fill the wing with water. Weigh it again. Subtract weights. Now you have the actual lift.

 

[cool_hardware52]

Get a scale. Fit the wing to a plate. Weigh it. Now fill the wing with water. Weigh it again. Subtract weights. Now you have the actual lift.

I'd suggest:

Weight the wing

Build up a rig, i.e. mount the wing to a back plate and cylinder.

Fill with water until the OPV pops, being careful to chase out any air bubbles.

Remove the wing full of water and weigh again.

Difference in the two weights is the actual capacity.

Tobin

 

[Insta-Gator]

Get a scale. Fit the wing to a plate. Weigh it. Now fill the wing with water. Weigh it again. Subtract weights. Now you have the actual lift.

Displacement is a wonderful thing.

 

[Spg01]

So the weight of the water in the wing is equal to the lift it will provide. So a 40lb wing should hold 4.79 gallons and 35lb wing should hold 4.19 gallons of fresh water. So it is easier to weigh it than to measure the gallons.

Thanks. I think I will stay warm in the house instead of going to the pool tonite.

 

[GrumpyOldGuy]

If you do have a 40lb wing instead of a 35lb wing, keep in mind the size difference is very, very small. Maybe 1/2 inch or so in each dimension, nothing to get upset about.

 

[Spg01]

If you do have a 40lb wing instead of a 35lb wing, keep in mind the size difference is very, very small. Maybe 1/2 inch or so in each dimension, nothing to get upset about.

I will agree it is not the end of the world. It is more to find out if I was fed a line of BS or the truth.

The truth goes a long way even if it is not what I want to hear.

 

[GrumpyOldGuy]

Let us know what you end up measuring.

 

[Spg01]

Cliff Notes:
Floats above water line with 40 lbs of lead in bathtub
Description on web says 35lb/18L of lift, 18L=39.66lbs if my math is not fubar
Wondering about giving vendor crap


Trial #1 was interesting - I could not dig up a scale at the moment and the pool deal fell through tonight so I ended up going with the old bathtub trial. All I had was 40lbs of hard/soft weight, so I started with 35 lbs. No problem, so I put the last 5lbs on and it was still quite buoyant with a fair amount of material still above the water line.

I inflated the wing by mouth and the relief valve never opened. I know there must be some tolerance in the manufacturing process, but I would not expect 5+ pounds over the rated lift to be normal (if it really was a 35lb wing). So now I need more weight just to find out how much it takes to drop it below the water line.

Tobin, can you comment on the tolerance of your wings compared to rated lift? I figured that you would have more knowledge on the subject than myself.

I just looked at their site and noticed that it states 35lb/18L of lift. If I converted right 18L = 39.66 lbs and 35lbs would be 15.86L. So I will assume it is a 40lb wing. Now I am tempted to go back and call BS.