Comments on: A news story today reports that cracks have been discovered in the wings of WhiteKnightTwo.

By: Pzatchok

Pzatchok — Fri, 16 May 2014 13:27:32 +0000

De-laminating layers is caused by air bubbles between the layers.

They do not glue the sections together so much as melt them together. Just like model glue. It liquifies the surface a little and allows the two parts to ‘mix’ together creating a very strong bond. Almost a single piece.
Unless there is air keeping the two parts from touching.

They will have to grind off the delaminating area and add on new material. If possible due to space limitations.

By: Kelly Starks

Kelly Starks — Wed, 14 May 2014 14:11:05 +0000

Virgin reportedly said they are NOT cracks, merely glue delaminating. This is likely true, since given the spar is the prime structural element holding the wings on – you couldn’t just repair it if it was cracked.

By: Pzatchok

Pzatchok — Wed, 14 May 2014 12:44:36 +0000

If the cracks in any way or direction go all the way through the material then forget it. That whole section needs replacement.

If its just a few layers of material that are delaminating or cracking then they can be repaired pretty well and more than likely made even stronger in the end.

The fact that they are trying to gloss over it does not look good. If it was something small and easily fixed they would just fix it and move on telling all potential customers everything. But this has the beginnings of a coverup.

By: joe

joe — Tue, 13 May 2014 03:48:39 +0000

I think if these cracks run perpendicular to the length of the spar that I would never trust any repair to that spar, if indeed these cracks run longways with the spar that may be it could be voids with the adhesives, maybe not so bad, with all that is known with composits and with Burt Rutan’s reputation, I am surprised at this outcome. Perhaps some refinements to this airframe are in order, tis the nature of EXPERIMENTAL aircraft.

By: Pzatchok

Pzatchok — Mon, 12 May 2014 23:04:24 +0000

Just because its made of composite, polymer carbon fiber or Some other new fangled substance does not make it magical.

Voids in laminates are a major problem in manufacturing them. Its the main reason that autoclaves are used to cure them. The autoclave uses pressure to squeeze out the air bubbles.
Which is fine for parts that fit into the autoclave. But when you have to stick two large parts together and together they do not fit into the autoclave then you have almost no way to remove the voids and have to rely on hand application to hope the voids can get squeezed out.
And I can guarantee you that there are always voids in joints like this. All you can do is make the joint far larger than the models say you need to and hope that its enough to compensate.

They know what caused the cracks. They just don’t know exactly what event started them. Stress. Stress if takeoff, or landing, or releasing the space ship, or landing with the spaceship. or excessive turbulence in flight.
In any event it was stress and that is not something they can avoid. So now they have to both repair the cracks and beef up the joints in some way.

They are not flying this year.
And they are not going to be carrying any superstars to space. The superstars insurance companies will not let them. Do you really think that Brad Pits insurance company wants to risk a billion dollar payout on some joy ride?

By: wade

wade — Mon, 12 May 2014 22:25:25 +0000

This is a major setback in time consuming studies of just what did cause the cracks and the conditions that induced them

By: wodun

wodun — Mon, 12 May 2014 20:30:23 +0000

Not good news considering how little it is used.