CG Trimming after Tail Boom Repair

A new weight and balance, after a tail boom repair, shows that several tens of pounds of trim weight needs to be added to a forward location in order to move the CG back into acceptable range. This fixes CG issue, but are there other concerns with doing this? Would be interested in experience of others.
Tom A

On Thursday, November 23, 2017 at 12:20:04 PM UTC-7, wrote:
A new weight and balance, after a tail boom repair, shows that several tens of pounds of trim weight needs to be added to a forward location in order to move the CG back into acceptable range. This fixes CG issue, but are there other concerns with doing this? Would be interested in experience of others.
Tom A

Please specify the glider type. We assume you mean that the c.g. needs to be moved forward into the correct range.

Some gliders have ballast weights that can be placed in the nose or near the front bulkheads, others will have lead epoxied into the nose.

You should investigate the potential of some ballast hidden somewhere in the tail. Or perhaps your CG calc's and/or measurements. A boom repair should not require that much ballast in the nose to get the empty airframe in CG range.

A boom repair should not require that much ballast in the nose to get the empty airframe in CG range.

I have seen boom repairs just short of having 2x4s inside, so if it is one of those, that much lead in the nose may be indeed required.

Uli
'AS'

On Friday, November 24, 2017 at 7:32:29 AM UTC-7, AS wrote:
A boom repair should not require that much ballast in the nose to get the empty airframe in CG range.

I have seen boom repairs just short of having 2x4s inside, so if it is one of those, that much lead in the nose may be indeed required.

Uli
'AS'

You mean like this?

https://www.dropbox.com/s/gy3qkujmyy...26.49.jpg?dl=0

On Saturday, November 25, 2017 at 10:24:14 AM UTC-5, Dan Marotta wrote:
On Friday, November 24, 2017 at 7:32:29 AM UTC-7, AS wrote:
A boom repair should not require that much ballast in the nose to get the empty airframe in CG range.

I have seen boom repairs just short of having 2x4s inside, so if it is one of those, that much lead in the nose may be indeed required.

Uli
'AS'

You mean like this?

https://www.dropbox.com/s/gy3qkujmyy...26.49.jpg?dl=0

Yep - pretty much like that. Still, my vote for the top price for the most terrible repair would go to a Ka6e with a Bondo'ed on cuff over one side of the all-flying elevator after an off-field landing mishap. I wonder how much lead in the nose that one required - provided a W&B was even done after that 'repair'.
Uli
'AS'

You mean like this?

https://www.dropbox.com/s/gy3qkujmyy...26.49.jpg?dl=0

On 11/24/2017 7:32 AM, AS wrote:
A boom repair should not require that much ballast in the nose to get the empty airframe in CG range.
I have seen boom repairs just short of having 2x4s inside, so if it is one of those, that much lead in the nose may be indeed required.

Uli
'AS'

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Dan, 5J

On Thursday, November 23, 2017 at 12:20:04 PM UTC-7, wrote:
A new weight and balance, after a tail boom repair, shows that several tens of pounds of trim weight needs to be added to a forward location in order to move the CG back into acceptable range. This fixes CG issue, but are there other concerns with doing this? Would be interested in experience of others.
Tom A

Other than the max allowable weight of non lifting parts there should not be any other issues if the repair was solid. Added weight in a tail boom repair (long tail moment) takes several times the added weight when added to the shorter nose moment. Having to add so much weight forward of the cg though shows that a sloppy and probably excessive repair was made.

Mike

I think I see the problem...
https://www.dropbox.com/s/gy3qkujmyy...26.49.jpg?dl=0

On 11/23/2017 2:02 PM, Mike C wrote:
On Thursday, November 23, 2017 at 12:20:04 PM UTC-7, wrote:
A new weight and balance, after a tail boom repair, shows that several tens of pounds of trim weight needs to be added to a forward location in order to move the CG back into acceptable range. This fixes CG issue, but are there other concerns with doing this? Would be interested in experience of others.
Tom A
Other than the max allowable weight of non lifting parts there should not be any other issues if the repair was solid. Added weight in a tail boom repair (long tail moment) takes several times the added weight when added to the shorter nose moment. Having to add so much weight forward of the cg though shows that a sloppy and probably excessive repair was made.

Mike


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Dan, 5J

My memory is a little hazy but I recall seeing Rudy Alleman's 301 Libelle at the 1981 15M nats in Minden with glassed on external longerons. I could have my facts wrong but apparently the tail boom had been broken a few times and he decided he didn't want to go thru that again.

Chip Bearden