Composite fuselage formers and wing ribs
12-08-2013, 09:56 AM
#26
I agree that any composite materials have to be used correctly, honeycomb is one of the more complex materials. It is essential to get the orientation correct with the stress loads. On the plus side, it's light and when used correctly is extremely strong. I have to be careful about what is said here but it is a key material that I use at work and it is used as a structural component on a several military aircraft.
12-09-2013, 03:11 AM
#27
The North American XB-70 was constructed in large from SS and Titanium honeycomb panels, I grew up and lived in the Lancaster, Palmdale, California area and got to see the first takeoff of ship #2 from the fence line of plant 42 as a young kid. There was also widespread use of this Technology in the SST. Anyway I also agree that all materials composite or composition have their place and must be correctly utilized for optimum strength and weight savings within a structure.
Bob
Bob
Last edited by sensei; 12-20-2013 at 07:23 PM.
12-09-2013, 06:32 AM
#29
The North American XB-70 was constructed in large from SS and Titanium honeycomb panels, I grew up and lived in the Lancaster, Palmdale, California area and got to see the first takeoff of ship #2 from the fence line of plant 42 as a young kid. There was also widespread use of this Technology in the SST. Anyway I also agree that all materials composite or composition have their place and must be correctly utilized for optimum strength and weight savings withing a structure.
Here is a honeycomb structural job we recently brought in, I designed the structure and headed up the program from a models only base line (no drawings) as my team manufactured everything you see completely in house at our facility from both 1.00" thick aluminum honeycomb for the structure and .500" Nomex honeycomb and pre preg for the aerodynamic leading and trailing edge fairings as well as the closeout side and bottom fairings, all machine fitting are manufactured from 7075 T6, 2024 T3 aluminum, and 15-5 stainless steel. There is over 3500 composite inserts and mill spec fasteners that tie the structure and aerodynamic fairings together for the expected XX000 lbs. of pay load and aerodynamic loads this will see. This program started less then 90 days ago at our facility and we are delivering it Wednesday of this week.
Bob
Here is a honeycomb structural job we recently brought in, I designed the structure and headed up the program from a models only base line (no drawings) as my team manufactured everything you see completely in house at our facility from both 1.00" thick aluminum honeycomb for the structure and .500" Nomex honeycomb and pre preg for the aerodynamic leading and trailing edge fairings as well as the closeout side and bottom fairings, all machine fitting are manufactured from 7075 T6, 2024 T3 aluminum, and 15-5 stainless steel. There is over 3500 composite inserts and mill spec fasteners that tie the structure and aerodynamic fairings together for the expected XX000 lbs. of pay load and aerodynamic loads this will see. This program started less then 90 days ago at our facility and we are delivering it Wednesday of this week.
Bob
12-16-2013, 10:02 AM
#30
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The original poster asked about alternatives to lite ply and I have been making one for years now. Just using leftover resin, scrap foam, and scrap glass cloth.
I posted about it in my Monocoupe build thread here: http://www.rcgroups.com/forums/showthread.php?t=2011807
Tom
I posted about it in my Monocoupe build thread here: http://www.rcgroups.com/forums/showthread.php?t=2011807
Tom
03-05-2014, 07:26 PM
#31
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I have been reading this thread with interest and I would like to add a few things.
Firstly, I have used end grain balsa with fiberglass or carbon skins for fuselage formers to very good effect. They are very stiff and strong, yet lightweight and very easy to bond. Another benefit to end grain balsa core is that you are able to bolt directly through it as it can with stand compression loads. Nomex honeycomb or foam cores will need to have hard points embedded to prevent the skins collapsing in on themselves. It should be remembered that the primary job of core materials is as a spacer to keep the composite skins apart. The greater the distance between skins will produce a much stiffer product for very little weight increase. I prefer to use 1/4" end grain balsa with fiberglass or carbon skins because of this and end up with a product that is as stiff as 1/4" Birch ply yet at a fraction of the weight.
The best way to laminate a honeycomb panel is to wet out the skins separately. One on your layup surface, the other on a sheet of polythene or similar material. Remove any excess resin from the fiberglass cloth with a bondo spreader (a glossy look is too much resin, satin look is about right) and put back into mix cup. Add a little fumed silica (Cabosil or Aerosil) to thicken up the remaining resin to sour cream consistency and spread a thin layer evenly on the wetted out fiberglass skins. This layer will act as the adhesive to bond the skins to the honeycomb. Place honeycomb on the fiberglass that you wetted out on the layup surface then apply the other fiberglass skin on top and peel off polythene backing. Apply a layer of peel ply and then a layer of perforated release film (this will limit the amount of resin draw). Apply breather/bleeder and vacuum bag down to the layup surface. Once cured, you'll have a lightweight panel without the worry of having filled the honeycomb cells with excess resin.
Diamond cutoff wheels are the best way to cut composite materials. Harbor Freight sells 1 1/4" dia wheels in packs of 5 and 1/8" mandrel for around $6.00 and they work great in a Dremel tool. You can easily cut through 1/8" solid carbon with these. As stated, wear a good respirator to prevent inhaling dust.
Firstly, I have used end grain balsa with fiberglass or carbon skins for fuselage formers to very good effect. They are very stiff and strong, yet lightweight and very easy to bond. Another benefit to end grain balsa core is that you are able to bolt directly through it as it can with stand compression loads. Nomex honeycomb or foam cores will need to have hard points embedded to prevent the skins collapsing in on themselves. It should be remembered that the primary job of core materials is as a spacer to keep the composite skins apart. The greater the distance between skins will produce a much stiffer product for very little weight increase. I prefer to use 1/4" end grain balsa with fiberglass or carbon skins because of this and end up with a product that is as stiff as 1/4" Birch ply yet at a fraction of the weight.
The best way to laminate a honeycomb panel is to wet out the skins separately. One on your layup surface, the other on a sheet of polythene or similar material. Remove any excess resin from the fiberglass cloth with a bondo spreader (a glossy look is too much resin, satin look is about right) and put back into mix cup. Add a little fumed silica (Cabosil or Aerosil) to thicken up the remaining resin to sour cream consistency and spread a thin layer evenly on the wetted out fiberglass skins. This layer will act as the adhesive to bond the skins to the honeycomb. Place honeycomb on the fiberglass that you wetted out on the layup surface then apply the other fiberglass skin on top and peel off polythene backing. Apply a layer of peel ply and then a layer of perforated release film (this will limit the amount of resin draw). Apply breather/bleeder and vacuum bag down to the layup surface. Once cured, you'll have a lightweight panel without the worry of having filled the honeycomb cells with excess resin.
Diamond cutoff wheels are the best way to cut composite materials. Harbor Freight sells 1 1/4" dia wheels in packs of 5 and 1/8" mandrel for around $6.00 and they work great in a Dremel tool. You can easily cut through 1/8" solid carbon with these. As stated, wear a good respirator to prevent inhaling dust.
