Aircraft scales

[Brett]

Hey all ,, I've finally come to that point where I need to do the weight and balance. I was hoping for some feedback on the types of scales one uses for this mission and how other people have gone about it. cheers in advance ..

 

 

[dazza 38]

Thats interesting , in regards to heavy duty bathroom scales.I dont know much about them (I only weight 96 KG ) anyway I would have thought that bathroom scales would be way out in their weight calculations at lets say at a guess 180Kg or more.The reason say this is because bathroom scales are pretty cheap to buy.

 

I would go with calibrated scales as Kyle has mentioned.

 

PS- Hi Brett if the aircraft is your Aeropup that is in your avatar, it maybe easier to trailer it to a airfield and get it weighed at a Aircraft Joint.

 

 

[fly_tornado]

Mass produced items always seem cheap compared to low production items. You can buy a whole car for less than a cost of a 912.

 

 

[Kyle Communications]

I just helped a fellow Savannah builder weigh his new baby. He got 3 of digital bathroom scales all the same from Bunnings I think about $25.00 each and they go to 150kg . All three were compared with the same heavy weight to make sure they were all pretty reliable. All 3 were within .3 of KG each so we used them to do his weight and balance. I believe you couldn't get any more accurate the only issue is they go off after 15 sec so all scales under the wheels then lift the aircraft one wheel at a time and measure each scale . We did this many times on each scale and each was exactly the sale to .1 kg every time.

 

Its a 2 person job by the way

 

Mark

 

 

[dazza 38]

Thanks Mark and Co. I have learnt something today. Ie-Accuracy of bathroom scales.

 

PS- If I made bathroom scales, I would make them under read over 115KG so fat people would feel better.

 

 

[pudestcon]

PS- If I made bathroom scales, I would make them under read over 115KG so fat people would feel better.

Make that over 100kgs will you dazza:wink:

 

Pud

 

 

[djpacro]

Just a point about weighing tail-wheel aeroplanes - accuracy of the small load on the scales at the tail is extremely important because of the large moment arm. You can do the same calculations as determining the cg to see exactly the significance of any inaccuracy in weighing.

 

 

[Kyle Communications]

Steves were 113kg on each main wheel and 78 something from memory the scales go to 150kg so were well within their limits and should have been accurate. But we did try to weigh his tool kit and they wouldn't record the 4kg odd of tools

 

Mark

 

 

[Guernsey]

Thanks Mark and Co. I have learnt something today. Ie-Accuracy of bathroom scales.PS- If I made bathroom scales, I would make them under read over 115KG so fat people would feel better.

There's an easier way to make them under read, place the scales on a carpeted floor rather than the solid tiled bathroom floor.

 

Being only 70 kg I weigh myself in the bathroom however, I weigh my wife on the carpet in the bedroom. Naturally she is naked to get complete accuracy so I can........................

 

Alan.

 

 

[Brett]

I have so far just used some cheap bathroom scales from bunnings to get a bit of a feel for how it's all done in the first place as this is all new to me regarding weights and balancing. They do only go to 150kg and the plane is weighing in at about 148kg on the fronts and 20 on the rear ,, a nice set of 0-200 kg you'd think would be a lot better as it would be nice to try it full of fuel and pilot to see where the cg changes with weight on board. Also a dial rather than electronic would be handy too to give a full time reading as small movements in tail position affect the weight on it so getting it right on the flying attitude will be crucial to an accurate result. goes from about 34kg in the 3 point attitude to 17-20 kg in the flying attitude.

 

I might just have to weigh it on carpet like you say Guernsey ,,,would give a a better payload if the scales said it weighed less

 

 

[Kyle Communications]

The only accurate way of course is to use balance beam scales. I am told guy at YCAB has 3 of them and nice small ones with all the measured weights

 

 

[Guest rocketdriver]

I purchased one high capacity glass top electronic scale from Big W. I levelled the plane on a level surface protected from the wind and with wooden pads under each wheel sufficient to support the scale properly. All the pads were the same thickness as the scale. Then the scale was placed under each wheel in turn. I got repeatable results (with less than .2 Kg difference at all times) which I averaged for each weighing. I made sure of the accuracy at low and medium weights by comparing two entirely different electronic scales and got the same answers on each. Not NATA level of quality assurance, but it worked for me!

 

Cheers

 

Martin

 

 

[biggles]

There's an easier way to make them under read, place the scales on a carpeted floor rather than the solid tiled bathroom floor.Being only 70 kg I weigh myself in the bathroom however, I weigh my wife on the carpet in the bedroom. Naturally she is naked to get complete accuracy so I can........................

Alan.

" Go on Alan , go on........................ "

 

Bob

 

 

[Diggler]

You could join the SAAA.

 

They have a set of 3 calibrated scales and alls you pay for is the cost of transporting them to and from your site.

 

Cheers

 

Rod

 

 

[Old Koreelah]

Hey all ,, I've finally come to that point where I need to do the weight and balance. I was hoping for some feedback on the types of scales one uses for this mission and how other people have gone about it. cheers in advance ..

Brett I too used a trio of cheap bathroom scales, but the results were unreliable. You need to "tap" the scales before you step on- that makes it a little difficult- you have to have a team to roll the plane on after you tap each scale. I also found considerable variations in the reading with analog scales.

Then I heard about cattle scales. Most livestock farmers will have a set of good-quality digital scales. They're robust and built for heavy, uncooperative loads, with a pair of long sensors you can place under the main wheels. My neighbour was very helpful and I got a very accurate reading for each wheel. He got the dust and spider's webs cleaned out of his scales and I even made him up a new box to carry them in.

 

Regards,

 

Lyle

 

 

[fly_tornado]

you farmers have it too easy!

 

 

[Old Koreelah]

you farmers have it too easy!

I'm no farmer, FT, just a lowly salary earner (ie taxpayer).

 

 

[solomon]

One bathroom scale will be enough for my plane since it only weighs 65kg , but only if I can get it to balance on one wheel.

 

 

[Old Koreelah]

One bathroom scale will be enough for my plane since it only weighs 65kg , but only if I can get it to balance on one wheel.

Solomon, you might be able to use kitchen scales!

 

 

[Guernsey]

Solomon, you might be able to use kitchen scales!

Tut Tut Tut...he wants to weigh his aircraft not his kitchen.

 

Alan.

 

 

[Guernsey]

" Go on Alan , go on........................ "Bob

...so I can get down on my knees to read the scales then lift my head and look her straight in the eye and tell her the results.

Stone the crows I didn't really think I would have to spell it out.

 

Short sighted Alan.

 

 

[Guest nunans]

Is anybody familiar with the hanging method where you hang the aircraft from the nose and tail and when the plane is completely level a plum bob from the hang point will drop down directly over the C of G,

 

This is for c of g measurement not all up weight though

 

 

[Old Koreelah]

Looks like the ideal method, Nuns. You just need a big enough hangar or shed. Finding a pair of strong points on the aircraft may be difficult, unless it was designed for such an exercise. Engine mounts and a wide, lightweight strap around the rear fuselage might do the trick. You may need to build a platform for the undercarriage and suspend it. Lots of care needed then to cancel out it's effects on total weight and balance.

 

In case you missed an earlier thread on the subject: http://www.recreationalflying.com/threads/aircraft-scales.34305/

 

I used a different method to back up my W & B calculations. I built some pads under my spar to support the aircraft on pair of rollers. Climbed in and got my wife to gently push it fore and aft until it was perfectly balanced. Did this several times with different fuel and baggage loads, marking the roller position each time. CoG was well within limits and only moved about 20mm.