Using Carbinge™ and Carbinge Keepers™ to attach wingtips with hinges (similar to the process with the cowling) is a great way to save weight, improve appearance, and increase strength.  The following case study compares and contrasts this process to traditional nutplates and screws, and explains the process.

Case Study

The aircraft, a Lancair IV, weighs about 3500# maximum. It's effective weight is doubled to 7000# at two G's. The wingtips or winglets need to support less than 10% of the total effective weight. Ten percent of 7000# is 700#. 

• Taking half of 700# at two G's (since this load is shared by two wingtips), you get 350# max load per wingtip or winglet. 
• Carbinge™ material on the bottom of the wingtip will be in shear load during positive G's while the aircraft is airborne. Carbinge™ is rated at 3000# per lineal foot in shear.
• It takes about 20" of Carbinge™ on top and 20" on the bottom for the wingtip attachments. 20" of Carbinge™ is rated for 5000# of shear stress. 
• It would take over 14.25 G's to reach the rated limit of the Carbinge™ attachment on the wingtips or winglets. 
• It would take twice that or 28.5 G's to reach the limit load of the Carbinge™. 

Comparing this approach to the use of nutplates and screws, you find that the older, traditional method of attachment spreads the loads to 8 or 10 points along the top and bottom of the wing,  thus concentrating and increasing the loads at smaller areas of the wingtip. This produces a weaker attachment. In contrast, Carbinge™ spreads the load equally and continuously along the entire length of the attachment because it is bonded to place.

The old method requires a row of screws in the skin while the Carbinge™ method combined with Carbinge Keepers™ is virtually invisible.

The old method causes small waves in the surface of the wingtip or winglet, because it holds the surface down at multiple points. Carbinge™ leaves no irregularities.

Maintenance of the old system requires unscrewing and rescrewing multiple screws into locknuts, taking a good bit of time and leading to stripped out screw heads.  Removing and replacing the hinge pins is straightforward, rapid and can be repeated countless times without breakdown of the parts.

How It's Done

Want to see how it's done? Art Bertolina has been kind enough to provide photos of his wingtip installation using Carbinge™ attachments. See them below.

Carbinge™ trimmed, fitted and clamped to place, then drilled for clecoes.   » View larger photo.

Carbinge™ clecoed and bonded to wing.   » View larger photo.

Second half of Carbinge™ is assembled then wingtip is positioned, marked and drilled for clecoes.   » View larger photo.

Wingtip assembled with pins partway in and Carbinge Keepers™ fitted.   » View larger photo.

IMPORTANT DISCLAIMER AND GUARANTEE: Use of Carbinge™ is at the purchaser's sole discretion and risk. Leading Edge Technologies makes no warranties, implied or expressed, with regard to the products or their suitability for any particular use except that they are rated to support 3,000 pounds per one-foot length of the hinge material. Carbinge Keepers™ are guaranteed not to back out and the solder joint is guaranteed not to fail. Remedies are restricted solely to repair or replacement of defective material, at manufacturer's discretion.