Baker Monitor AC Mast Pipe Balance

[billcobb]

I just put up an Aermotor A602 and with the advice here, put it up in one assembly: Fan, Tail, Motor. Single point pickup, balanced right at the mast pivot with the tail unfurled.

Now I've acquired a Monitor AC (8'). On a stand with motor, fan and tail (complete, it's VERY tail heavy. I read comments here that that causes undesirable wear on the mast pipe, no matter what the brand or model, so I've altered/shortened the tail backbone to bring it into balance.

On my parts, the center of gravity of the tail assembly (backbone + tail vane) is about 54" from the hinge. A fish scale shows it to weigh 29 lbs, measured at this point. Mounted on the mill, there is an 8# excess tail weight at the tail CG (measured with a fish scale. So, the 29# times the 54" gives me a total 130.5 ft-lb moment with a 36 ft-lb moment excess. Therefore The 130.5 minus 36 = 94.5 ft-lb moment would result is a balanced windmill with the tail unfurled. I can't change the tail weight very much, so I computed a 94.5 ft-lb divided by 29# gives me a 3.258 tailbone length for perfect balance on the mast pipe. 54" minus 3.258 times 12" is about 15" excess tail length.

So, I cut off 14.5" of the upper and lower tailbones, drilled new hinge bolt holes and bingo, the balance is pretty darn good now. When I toss a few quarts of oil in the crank case, it ought to be just about perfect.

Was there any reason NOT to do this ? My main reason was to make it just as easy to raise this job up as 1 unit just like I did with the A602. It still looks like a windmill. My Heller-Aller 36 blade 8' jobs have tails so heavy that I can hardly pick them up off the ground, and they are balanced pretty good. My F&W 24, 26 and 37's are not so well balanced and show wear at the storm stays.

What do all of you think about this ? Th

20190625_204232.jpg

e picture is Before Modification. The turquoise paint is good quality 2x free garage sale rattle can stuff before turning the mill red white and blue.

[windybob]

I don't have a problem with it. It would be nice if it had a hoop to hook it to like an Aermotor. The issue ( or one) with an AC ( 1932-1939) is that when the wind blows on the wheel it pushes back against the tower top casting. If the neckpipe is worn at this spot, it really needs fixed or changed. Then of course you have that lovely ball cup under the stormstay. The upper race is bolted in the bottom of the neckpipe. This usually gets trashed after the balls grind down. Anyway, we just got done repairing one yesterday. Replaced the brakeshoe, installed a new turntable etc etc.

[Ron Stauffer]

Bill
Trimming the bone was unnecessary - just apply the appropriate counterbalance weight of turquoise paint to the vane and you would have been done....

I have noted more mast wear on mills that I have taken down that were in seasonal use. Prevailing winds are normally pretty directional so a mast will wear directional. Then there is more side pressure on a mast when furled. Just pickup up an Aermotor in the furled position to see. But yes it takes 30-40 years of wear for this to be visually apparent

Ron Stauffer
Montrose CO

[billcobb]

Now, on the day I was born
The nurses all gathered 'round
And they gazed in wide wonder
At the joy they had found
The head nurse spoke up
Said "leave this one alone"
She could tell right away
That I was bad to the bone...

[Bryon]

Now, on the day I was born
The nurses all gathered 'round
And they gazed in wide wonder
At the joy they had found
The head nurse spoke up
Said "leave this one alone"
She could tell right away
That I was bad to the bone...

-G. Thorogood

[Aermotor Fan]

Bill,
Do you have the Monitor wheel for your mill?

Adam

[billcobb]

I believe so. Spars fit, blades fit, correct rotation direction. At first I was wondering if the tail was from a 10' mill. I'm pretty happy with the balance at this stage.