This is probably one of my most unjustified fears, and thus I think it is a good topic for discussion here.
If I ever own an airplane, it will probably be an experimental due to lower cost. Either one somebody else built, or if I happen to have a lot of time, a kit that I can build myself. However, I have noticed that most experimental kits out there have fabric fuselage and fabric wings.
Or Kitfox Aircraft
Or even the good old Piper Cub
My fear is that if I have a birdstrike, or if a bird scrapes the wing with its feet, or a tiny celestial body falls on the wing at high speed and scrapes the wing (not likely, but you get the idea), the fabric will tear up and blow off the wing. I guess you can still fly with a tear up fuselage, but you cannot fly without fabric on the wing.
Aluminium aircraft seem to handle this better, in many cases, you can land:
So what do you think, is my fear justified or not?
The wing leading edges are still sheet metal (or wood) with internal ribs. The fabric is generally glued to the leading edge with an overlap and the edge trailing downstream and covered by an extra tape.
With a J3 Cub or Champ you may be more concerned about protecting the trailing edges against bird strikes!
The fabric is also stitched or riveted to the wing ribs which should limit a tear spreading span-wise. Tail feathers will usually have a steel tube forming the leading edge.
There have been tragic accidents due to fabric peeling off, such as Steve Wittman’s, but they are generally related to incorrect manufacture.
An accident like this.
or the more famous one of the Jodel landing light coming off and taking the fabric with it. Yes, they would make you think.
An accident like this.
The fragmentation of the No. 2 rib is evidence of an impact on the upper surface, probably by a small bird, which resulted in its disintegration; pulling an initial section of fabric from the area. Following this failure, the remainder of the fabric came away in two large sections probably as a result of non-standard aerodynamic loads on the upper wing, creating a force on the fabric that it was not designed to withstand.
Scary that a small bird hitting the upper part of the wing can cause such damage. He wouldn’t probably make it if it wasn’t a biplane.
The fabric is actually pretty strong, and in case of the wing is rib stitched. The construction of the Auster wing for example has a metal leading edge D section (the metal going back to the front spar) with the fabric glued to the leading edge metal, then rib stitched behind the D section. This is quite a common arrangement. Clarence Taylor designed the Auster that I have, as well as the Taylorcraft and Cub, and they will have the same structural arrangement. I know the Decathlon and Citabria have a very similar strucutral arrangement. It’s pretty secure. Any impacts with birds etc (please, no jokes about my plane being so slow that birds are likely to collide with the trailing edge :-)) are going to hit this metal D-section and likely will do similar damage as it would to a metal skinned wing.
There are very few accident reports caused by a separation of fabric, and probably for every accident being intimately related to the wing being fabric, there’s probably one intimiately related with the wing being metal, too.
One thing to understand about fabric covered aircraft is there is a higher long term maintenance cost for your fuselage and wings, as periodically the fabric must be renewed. On the other hand, fabric renewal means the airframe is periodically subjected to a much deeper inspection than a metal aircraft ever has, and structural issues can be found before they turn into in-flight emergencies.
A bigger issue than fabric for bird strikes is the thickness of the aluminum used on the leading edges back to the spar – an issue common to both fabric and all metal wings. In the interest of minimizing weight on slow aircraft that leading edge material is sometimes as thin as 0.016 inches, or 0.4 millimeters. Of course you can say the same about thin plexiglass windshields and other areas of very light aircraft, nowhere is terribly resistant to a bird strike. That is offset by the energy of collision being related to the square of the relative speed at impact.
Our fabric-covered wing was stripped after a wood/glue problem was detected on a 100 hour check, performed by a PPL Group member. After full examination and repair by an LAA Inspector, it’s been recovered, and we’ll fit it after the New York celebrations. The previous, and new fabrics are synthetic and strong.
Some modern systems are not stitched. Our’s is.
I hit a fence post with a wood-and-fabric wing 24 years ago, short of flying sped, but well above taxi. Damage did not reach the mainspar. I flew it out, repaired, a few days later.
I was signalling for a wood-and-fabric glider winch launch, and an instructor was standing close to take a photo. The wing struck his head, fortunately between the wing ribs. The glider pilot noticed nothing until he landed. The photographer noticed nothing for more than a day, when he asked a nurse what happened.
The incident where a Jodel landed with a whole panel off was cotton, and about 40 years old. An accident history may be good for older wood-and-fabric aircraft.
I wouldn’t trust fabric. Never been properly tested. An accident waiting to happen! :)
That’s exactly what I tell everybody! Important thing to remeber is that wood and fabric is a deadly combination therefore not only an accident waiting to happen but a fatal accident waiting to happen
I strongly belive and try to shary the message that wood/fabric airplanes should be sold at price of fireplace wood….
In spite of all that this, nice Robin/Jodel types that I’m interested in seem to at least keep their prices and what’s more frustrating they are increasingly difficult to find
bottom line: wood and fabric wings are very dangerous!
Go fly a Piper Cub and you will not care about this anymore. It is just a lot of fun!
Fabric aircraft are completely safe. The fabric is so strong that you are not able to punch through it with your fist. You must have something sharp to cut through it.
I fly a lot of both types and do not bother, the lower speed of most fabric aircraft makes it quite safe as well.