Questions on weighing the airplane

[beeryboats]

Thinking ahead on my restoration of this KF4, at some point I'll need to weigh it and do a new weight and balance. Many years ago when I worked at a Beechcraft dealership we had nice big platform scales for the little birds and load cells for the KingAirs. What the heck am I going to use for my Kitfox? And I don't think we ever did weigh a tail dragger. It has to be level to weigh, so do I put a bathroom scale on a short ladder?!?!

This is the stuff that keeps me up at night during the winter when I can't work on the airplane.

[Av8r3400]

I used "heavy (https://www.amazon.com/Etekcity-Stainless-Digital-Bathroom-Technology/dp/B01HBC4QUO/ref=sr_1_8_a_it?ie=UTF8&qid=1518226908&sr=8-8&keywords=400+lb+bathroom+scale)" bathroom scales for the mains and a regular scale for the tail after leveling the plane.

[beeryboats]

I used "heavy (https://www.amazon.com/Etekcity-Stainless-Digital-Bathroom-Technology/dp/B01HBC4QUO/ref=sr_1_8_a_it?ie=UTF8&qid=1518226908&sr=8-8&keywords=400+lb+bathroom+scale)" bathroom scales for the mains and a regular scale for the tail after leveling the plane.

Are you saying I'm heavy?!?!? Lol
Thanks!

[ken nougaret]

I used "heavy (https://www.amazon.com/Etekcity-Stainless-Digital-Bathroom-Technology/dp/B01HBC4QUO/ref=sr_1_8_a_it?ie=UTF8&qid=1518226908&sr=8-8&keywords=400+lb+bathroom+scale)" bathroom scales for the mains and a regular scale for the tail after leveling the plane.

I did the same thing. Then after i was flying i took it to work and weighed it again using load cells on jacks. I found my home scales to be 20 lbs heavier. In a way that was good news.

[beeryboats]

I see a lot of 300-400 pound max scales. How high do I need to go?

[beeryboats]

I did the same thing. Then after i was flying i took it to work and weighed it again using load cells on jacks. I found my home scales to be 20 lbs heavier. In a way that was good news.

Did you do the "dog food bag" calibration check???

[Av8r3400]

I see a lot of 300-400 pound max scales. How high do I need to go?

The Mangy was about 700#. It's a modified Model IV-1200 Classic. The mains were ~325 each.

My old IV-1050 was 650#, and showed about 300 on the mains.

[Av8r3400]

Did you do the "dog food bag" calibration check???

No, but I did the bag of wood pellets calibration test. :D

[beeryboats]

So I need a 400lb scale.

[PaulSS]

Quite a good article I thought:

Weighing a taildragger (http://mybearhawk.com/finish/weight.html)

[rv9ralph]

My EAA Chapter bought a set of auto scales, 4 load cells, we use 3, it gives the weight at each station and you can tare it if you need to put any blocks on the scale.
You might check your EAA Chapter or any local auto clubs to see if they have scales you can borrow.

Ralph

[rainbird]

Used a platform grain scale ( certified ) and a bathroom scale. Jack the plane up and put the mains on small platforms that are the EXACT night as the platform scale. Now raise the tail to level the plane with the tailwheel resting on the bathroom scale. Now the weighing begins. Jack up one main one inch and slide out the platform under that main then roll the platform scale under that wheel and weigh it. Do the same for the other main. Read the bathroom scale for tail weight.

For my S7. Left main 366#. Right main 367#. Tail 61.75#
Total 794.75#

Be sure to measure the moment arms while the plane is leveled.

[beeryboats]

Quite a good article I thought:

Weighing a taildragger (http://mybearhawk.com/finish/weight.html)

very good article. thanks!

[HighWing]

The pictured item was once available at Aircraft Spruce. It essentially multiplies the capacity of a typical bathroom scale by two or three. One for each of the main gear wheels and the scale only on the tailwheel. I have a small work bench that I positioned under the tailwheel and several pieces of wood for shims helped level for weighing.

[jrevens]

The pictured item was once available at Aircraft Spruce. It essentially multiplies the capacity of a typical bathroom scale by two or three. One for each of the main gear wheels and the scale only on the tailwheel. I have a small work bench that I positioned under the tailwheel and several pieces of wood for shims helped level for weighing.

I have a set of those Ruggles scales also, Lowell (purchased from Aircraft Spruce). I've weighed a lot of airplanes and loaned them to many fellow builders also over the years. Correct me if I'm wrong, but I believe that the 2 positions for the wheel platforms give 2 to 1 or 4 to 1 ratios, not 3 to 1. In other words, a 300 pound "bathroom" scale can weigh up to 600 lbs. or 1200 lbs., but I've never had to use the 4 to 1. Any errors are twice as great in that position of course.

A few years ago I saw a great deal on some low profile digital scales on eBay (I think they might have been found by someone on this forum). I believe that they cost me less than the three bathroom ones. They work beautifully, and are extremely accurate. They can be powered by batteries or a plug-in power supply. I built a couple of simple wooden ramps out of 3/4" boards. They work great too... there's no tapering, you just roll the mains up over a 3/4" high lip 3 times to reach the level of the scales. There's no tendency to roll backwards as you get to each level, like there would be with tapered ramps. Works great.

[HighWing]

John you are right about the ratios. Placing the platform on the center mount - multiply the reading by 2. On The outboard, multiply BY 4.