[DeTomaso] FW: NPC Probably not new to you aeroheads but wow-

[Charles McCall]

I would be very nervous about repairing a ding in CF. I’ve spent a good
amount of time watching the fabrication of Ailerons and flaperons for the
Boeing 777
 They build the parts up by laying one very specific shape of
fiber on top of another very specific shape of fiber, building a sandwich of
interwoven pieces of cloth. The shape of these pieces of cloth is quite
important to the structure and strength of the final part. They are not just
long pieces of cloth laid one on top of another – it is hard to explain, but
the pieces of cloth are not uniform at all, If you could simply cut out a
bad part and attach a new part, then the fabrication process would be a
whole lot simpler and less expensive – they would do it that way from the
beginning. They may have 10 layers of cloth, each one sandwiched in a
different manner..

 

From: MikeLDrew at aol.com [mailto:MikeLDrew at aol.com] 
Sent: miércoles, 17 de junio de 2015 21:27
To: gow2 at rc-tech.net; charlesmccall at gmail.com
Cc: detomaso at poca.com
Subject: Re: [DeTomaso] FW: NPC Probably not new to you aeroheads but wow-

 


In a message dated 6/17/15 11 33 50, gow2 at rc-tech.net writes:





Ironically one of the problem with composites is repair. When you run
something like carbon fiber in a solid line from wing tip to wing tip, if
you punch it with an ice pick you have compromised the strength of the
entire string.



>>>...and I think that's something that may have been overlooked in the
stampede towards CF construction of airliners.  There are a lot of
minimum-wage boneheads driving catering trucks and whatnot that routinely
bump into the airplanes they are servicing, causing localized damage.  Such
airplanes are immediately withdrawn from service and undergo an inspection,
and then often a localized patch is applied and the airplane is ready to go
again in just a few hours.  It's not uncommon to see airplanes with multiple
such patches on the skin; eventually they will go for a heavy maintenance
(akin to a ground-up restoration in automotive circles) and then the
offending panels are removed and replaced with new ones.

This begs the question--how does a CF airplane respond when a bozo crashes
into it with a catering truck?  CF doesn't 'ding' as far as I know.  Can
localized repairs be made?

F-1 cars may prove reassuring in this regard.  Recall that at this year's
Montreal GP, Lewis Hamilton comprehensively smashed his car on the first
day's practice, hitting the wall hard, pieces and parts flying everywhere
etc.  The whole side of the car was demolished; however the team was able to
drag the wreck back to the garage and rebuild it overnight; he went on to
win the race.  So that gives some cause for optimism perhaps?

Mike

-------------- next part --------------
   I would be very nervous about repairing a ding in CF. I've spent a good
   amount of time watching the fabrication of Ailerons and flaperons for
   the Boeing 777... They build the parts up by laying one very specific
   shape of fiber on top of another very specific shape of fiber, building
   a sandwich of interwoven pieces of cloth. The shape of these pieces of
   cloth is quite important to the structure and strength of the final
   part. They are not just long pieces of cloth laid one on top of another
   - it is hard to explain, but the pieces of cloth are not uniform at
   all, If you could simply cut out a bad part and attach a new part, then
   the fabrication process would be a whole lot simpler and less expensive
   - they would do it that way from the beginning. They may have 10 layers
   of cloth, each one sandwiched in a different manner..


   From: MikeLDrew at aol.com [mailto:MikeLDrew at aol.com]
   Sent: miercoles, 17 de junio de 2015 21:27
   To: gow2 at rc-tech.net; charlesmccall at gmail.com
   Cc: detomaso at poca.com
   Subject: Re: [DeTomaso] FW: NPC Probably not new to you aeroheads but
   wow-


   In a message dated 6/17/15 11 33 50, [1]gow2 at rc-tech.net writes:

   Ironically one of the problem with composites is repair. When you run
   something like carbon fiber in a solid line from wing tip to wing tip,
   if
   you punch it with an ice pick you have compromised the strength of the
   entire string.

   >>>...and I think that's something that may have been overlooked in the
   stampede towards CF construction of airliners.  There are a lot of
   minimum-wage boneheads driving catering trucks and whatnot that
   routinely bump into the airplanes they are servicing, causing localized
   damage.  Such airplanes are immediately withdrawn from service and
   undergo an inspection, and then often a localized patch is applied and
   the airplane is ready to go again in just a few hours.  It's not
   uncommon to see airplanes with multiple such patches on the skin;
   eventually they will go for a heavy maintenance (akin to a ground-up
   restoration in automotive circles) and then the offending panels are
   removed and replaced with new ones.
   This begs the question--how does a CF airplane respond when a bozo
   crashes into it with a catering truck?  CF doesn't 'ding' as far as I
   know.  Can localized repairs be made?
   F-1 cars may prove reassuring in this regard.  Recall that at this
   year's Montreal GP, Lewis Hamilton comprehensively smashed his car on
   the first day's practice, hitting the wall hard, pieces and parts
   flying everywhere etc.  The whole side of the car was demolished;
   however the team was able to drag the wreck back to the garage and
   rebuild it overnight; he went on to win the race.  So that gives some
   cause for optimism perhaps?
   Mike

References

   1. mailto:gow2 at rc-tech.net