The One Time Auxiliary Fuel Tank in my Mooney

[Shadrach]

10 hours ago, Mooney Dog said:

A few people here have reference the 120lb limit for the baggage compartment. I dont have my 1965 poh on hand but i was sure it was limited to 100lbs 

 

Regardless on the original install of the tank, it was listed as 25lbs empty. Im really unsure. 

 

I should be getting a new WB Thursday. 

I have a AFM from 1963. It says 120lbs for baggage. Your W&B is FUBAR. Are you relying on the same folks that generated your current W&B to calculate it with scales?

 

 

[Mooney Dog]

43 minutes ago, Shadrach said:

Are you relying on the same folks that generated your current W&B to calculate it with scales?

HAHA Thats funny. No, no i am not. 

 

And interesting. I checked the TCDS and it also says 120. Hmmm. Wonder if the tank is really 25lbs like it says on that old WB sheet now, and if it is why is my plane now limited to 100lbs in the baggage compartment. 

Edited October 10, 2021 by Mooney Dog

[ArtVandelay]

HAHA Thats funny. No, no i am not. 
 
And interesting. I checked the TCDS and it also says 120. Hmmm. Wonder if the tank is really 25lbs like it says on that old WB sheet now, and if it is why is my plane now limited to 100lbs in the baggage compartment. 

There’s tank weight and then additional hardware associated with it (hoses, valves, etc).

[Mooney Dog]

10 minutes ago, ArtVandelay said:

There’s tank weight and then additional hardware associated with it (hoses, valves, etc).

would that not go through the body and to the wing, thus not associated with the actual baggage compartment itself? I still am looking for the original drawing that got the tank approved for install, there might be something in them. 

[carusoam]

Looks like the guys that developed this cool STC kept to the 120LBs max limit…

Combine the fuel weight and the hardware weight… see if it all adds up to 120LBs….

 

We are allowed to substitute all kinds of fuel and people weight between the cabin and wings….

But actually putting 130LBs in baggage area opens a whole new can of certification worms…  

Somebody once put another body in the back of the M20C… the five seater flew, but not for very long…. Or very far…

The fifth person would have had to be stick like to be under 120 LBs…

Everyone is smiling in the before pics…

 

Good luck with getting all the real weights and maths correct… it won’t be that hard….

Best regards,

-a-

[steingar]

On 10/9/2021 at 1:02 AM, Mooney Dog said:

Bath math from the 1970s

Says you.  I took off with it.  Yeah, I could feel it heavier in the aft end, but it exhibited no problems at all lowering the nose and flew just fine.  Folks in the 1960's (when mine was built) were just fine at math.  They sent some guys to the Moon using slide rules.

[Mooney Dog]

2 hours ago, steingar said:

Says you.  I took off with it.  Yeah, I could feel it heavier in the aft end, but it exhibited no problems at all lowering the nose and flew just fine.  Folks in the 1960's (when mine was built) were just fine at math.  They sent some guys to the Moon using slide rules.

The ability to send someone to the moon using slide rules doesnt change the fact that subtracting weight when you should add it means there will be errors in the future weight and balances of the airplane. 

 

Even if its "fine to do it" right now the math says no, its not. The CG is aft of the envelope and until i can get information that says otherwise, even if its "safe", its not legal. 

[Mooney Dog]

Well my WB problems are possibly over.

 

Put the plane on scales, and unsurprisingly I found an extra 100lbs. The good news however is the CG shifted forward to 47.2 which lets me put things in the back again! Fully loaded for a trip this week. 5 hours of nonstop flying time with that hour reserve I like! (+/- some numbers)  

[carusoam]

Great follow up MD!

Where did the 100# come from?

Best regards,

-a-

[Mooney Dog]

7 hours ago, carusoam said:

Great follow up MD!

Where did the 100# come from?

Best regards,

-a-

Dirt, grime, the inaccuracy of the scales used to weight the plane in 1965. All that fun stuff. Ive always kinda known older plane reweighed are going to have "gained" some weight but never realized it could but in the neighborhood of 100 for a small plane. I expected like 30 or 40. 

Just noticed the graph i posted is slightly inaccurate. It starts at too low a weight but it basicly looks just like that just shifted upwards a bit. 

[cliffy]

When I first weighed my airplane years ago I found a mistake (to my detriment) to the tune of 90 pounds in the factory's first W&B sheet.

I gained in useful load on that one.

Also its a good idea to actually measure the distance between the datum and the center of the wheel axles for the calculations. Everything published may not be accurate. Drop plumb bobs and use a tape measure.

Also if you ever cross an international border with your airplane US Customs WILL want to see the paper work for the legal installation of that baggage tank. 

Edited October 23, 2021 by cliffy
FTA