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Max Weight of Non Lift Producing Components



 
 
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  #1  
Old November 30th 17, 05:08 AM posted to rec.aviation.soaring
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Default Max Weight of Non Lift Producing Components

In addition to max gross weight, some glider manuals specify a max weight for non lift producing components. But I haven't found much discussion of the significance of exceeding the max or information that would allow one to calculate the weight of non-lifting components (like a breakout showing the weights of the wings, etc.)

Would appreciate some discussion by those in the know.

Tom
  #2  
Old November 30th 17, 05:13 AM posted to rec.aviation.soaring
Tony[_5_]
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Default Max Weight of Non Lift Producing Components

the only way to know is to weigh the wings separately. That is what we did the last time we did a W&B on the Cirrus. That was part of incorporating the Tech Note from Schemmp Hirth to increase the weight of non lifting parts.

Some airplanes, especially twin engine airplanes, have a maximum zero fuel weight which is a similar concept.

  #3  
Old November 30th 17, 05:39 AM posted to rec.aviation.soaring
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Default Max Weight of Non Lift Producing Components

From the BGA:

5. Non-Lifting Parts. For sailplanes where the Leading Particulars specify a maximum weight
of non-lifting parts, it will additionally be necessary to weigh the wings to enable the weight of the
fuselage and tailplane to be calculated; this is the empty weight of non-lifting parts.


I can't say what the significance of exceeding the max would be, but from general life experience exceeding the max of anything is usually a bad idea.

RC

  #4  
Old November 30th 17, 05:45 AM posted to rec.aviation.soaring
Larry Suter
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Default Max Weight of Non Lift Producing Components

Lot of gliders have a maximum weights with water ballast that's a couple hundred pounds greater than maximum weight w/o water ballast.

I think the maximum weight of non-lifting components is so you don't think you can put all that extra weight in the fuselage. My POH also has this, "Note: Water ballast in fuselage belongs to non-lifting parts."

Larry
  #5  
Old November 30th 17, 07:06 AM posted to rec.aviation.soaring
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Default Max Weight of Non Lift Producing Components

On Wednesday, November 29, 2017 at 8:08:26 PM UTC-8, wrote:
In addition to max gross weight, some glider manuals specify a max weight for non lift producing components. But I haven't found much discussion of the significance of exceeding the max or information that would allow one to calculate the weight of non-lifting components (like a breakout showing the weights of the wings, etc.)

Would appreciate some discussion by those in the know.

Tom


I think Larry's interpretation seems plausible. When I've seen a separate limit called out for non-lifting components, it generally seems to be in the context of water loading. The wings are, in a sense, self-supporting in flight, whereas the fuselage hangs off of the wings. So it makes sense to call out a separate limit for the non-lifting parts; particularly when water is involved.
Tom
  #6  
Old November 30th 17, 10:40 AM posted to rec.aviation.soaring
Tango Whisky
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Default Max Weight of Non Lift Producing Components

Le jeudi 30 novembre 2017 05:39:23 UTC+1, a écritÂ*:
From the BGA:

5. Non-Lifting Parts. For sailplanes where the Leading Particulars specify a maximum weight
of non-lifting parts, it will additionally be necessary to weigh the wings to enable the weight of the
fuselage and tailplane to be calculated; this is the empty weight of non-lifting parts.


I can't say what the significance of exceeding the max would be, but from general life experience exceeding the max of anything is usually a bad idea.

RC


Exeeding max weight of non-lifting parts makes you exceeding the structural limits of the plane (i.e. you start eating up the safety factor of 1.5), which is generally acknowledged as being a fairly stupid idea.

MTOW is not really connected to max weight of non-lifting parts.
  #7  
Old November 30th 17, 04:44 PM posted to rec.aviation.soaring
Dan Marotta
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Default Max Weight of Non Lift Producing Components

While studying for my Flight Engineer license back in the 70s (do they
have Flight Engineers any more?), it was explained that the max weight
of non lifting components had to do with the strength (bending moments)
of the wing spar.Â* Help us out here, Steve L.

MTOW has, I believe, to do with landing gear, brakes, tires, etc. Think
MV**2 during an aborted takeoff.Â* Higher weight - higher takeoff speed
- WAY higher energy to dissipate, that V squared component.

On 11/30/2017 2:40 AM, Tango Whisky wrote:
Le jeudi 30 novembre 2017 05:39:23 UTC+1, a écritÂ*:
From the BGA:

5. Non-Lifting Parts. For sailplanes where the Leading Particulars specify a maximum weight
of non-lifting parts, it will additionally be necessary to weigh the wings to enable the weight of the
fuselage and tailplane to be calculated; this is the empty weight of non-lifting parts.


I can't say what the significance of exceeding the max would be, but from general life experience exceeding the max of anything is usually a bad idea.

RC

Exeeding max weight of non-lifting parts makes you exceeding the structural limits of the plane (i.e. you start eating up the safety factor of 1.5), which is generally acknowledged as being a fairly stupid idea.

MTOW is not really connected to max weight of non-lifting parts.


--
Dan, 5J
  #8  
Old November 30th 17, 04:56 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Default Max Weight of Non Lift Producing Components

I believe you are correct, you don't want to overload the spar with fuselage weight, thus, spread it out through the wings.
I know some ships had water in the wings but also additional in a tank in the fuselage to get the wing loading up due to low volume wings. You would load the wings, then finish off with the fuselage. Dumping ballast is fuselage first, then wings.

As to MTOW, some larger aircraft also have a MLW, max landing weight which I believe is mostly due to loads when the mains hit the runway.
So, some aircraft can take off at a higher weight than they can land! So, if they run into an issue, they may have to fly around to burn fuel off to get within landing weight, or even dump fuel (don't tell the EPA!).
  #9  
Old November 30th 17, 04:59 PM posted to rec.aviation.soaring
Steve Leonard[_2_]
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Default Max Weight of Non Lift Producing Components

On Wednesday, November 29, 2017 at 10:13:28 PM UTC-6, Tony wrote:
the only way to know is to weigh the wings separately. That is what we did the last time we did a W&B on the Cirrus. That was part of incorporating the Tech Note from Schemmp Hirth to increase the weight of non lifting parts.



Or, if you want to know how much the fuselage and tail weigh, you can weigh them rather than weigh the wings and subtract that from the empty weight. The former gives you the weight you really want to know. The latter assumes the previous empty weight is still accurate, and there there have been no changes made to anything in the fuselage or wings.

Steve Leonard



  #10  
Old November 30th 17, 05:07 PM posted to rec.aviation.soaring
Tony[_5_]
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Default Max Weight of Non Lift Producing Components

We weighed everything together and then the wings. Felt that was easier than trying to hold the fuselage with tail attached upright and on the scales.
 




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