Jump to content

Recommended Posts

  • Replies 35
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted

there is very little structurally wrong with that...its a surface scuff that i doubt will lead to failure in the long term. This is going to fall under the wear a tear portion of an assessment.

 

I had a fair bit of composite experience, and in that area shear is maximised and you into the thicker area of the lay up, so ride it.

 

As for the fix, two white thick cable ties, as preventative, otherwise, an extremely thin alu, plate, epoxied over the frame arm, will look pretty and work a treat, but you will need to DIY.

Posted (edited)

 

 

Same applies to old people's hips

 

All people get old, that is why you have to enjoy life while you can. Age will not pass you unless you die young.

Edited by eccentric1
Posted

In my line of work, we do a fair amount of destructive testing on composites, and the one material i would not mess around with is Carbon. (hence the fact i wont buy a carbon frame). When things are going right, carbon is hard to beat, but when you get a small crack that can propagate, just one small bump is enough to for all hell to break loose.

I think you should get it checked out. Sometimes we even get frames x rayed because a lot of cracks could form in the bottom layer and you would not even know about it.

Would you ride in an aircraft with wings/tailplane/fuselage made from carbon? ;-)

Posted

Would you ride in an aircraft with wings/tailplane/fuselage made from carbon? ;-)

Isn't one of the advantages of carbon fibre that you can get better control of crack propagation? I read somewhere that a crack may be able to grow fairly easily within a ply, but when you've got plies of different orientation, the crack doesn't grow across the plies. Provided it's not unidirectional and provided you've got enough other plies to share the load, the crack isn't a huge problem.

Posted

I have been looking for those plates, but to no avail. They are actually alluminium and shaped to fit the frame, so not sure if you can buy them.

 

Now I have heard it all! Anyone else see the irony in looking for aluminium to stick onto carbon?

Posted

Now I have heard it all! Anyone else see the irony in looking for aluminium to stick onto carbon?

 

Aluminium panels like that are cheaper to replace than CF. I think they're meant to come off if they need to. Only problem is where do you get them?

 

Don't think I want to phone Concept Cycles, those little things probably cost more than my frame from them.

Posted

Would you ride in an aircraft with wings/tailplane/fuselage made from carbon? ;-)

 

lol, as long as it has high safety factors. Fatigue in composites is still a grey area.

Dont get me wrong, i am not a hater, but when it comes to failure, i would rather ride a dented alu frame then a cracked carbon one. (And I fall a lot)

P.s. So its been established thats it is just a chip. In that case, keep calm and carry on.

Posted

I find it amusing that people say things like "carbon snap crackle pop etc." but don't realize that they have flown to Europe and back at 1000 km/h, 12km above the ground on a 5 year old plane with carbon composite structures in the wings, tail, engine housings etc.

Posted

I find it amusing that people say things like "carbon snap crackle pop etc." but don't realize that they have flown to Europe and back at 1000 km/h, 12km above the ground on a 5 year old plane with carbon composite structures in the wings, tail, engine housings etc.

 

Although there was that one Airbus who's tail snapped off in a wake turbulence over Long Island, Nov 2001, composite lug popped:

 

American Airlines Flight 587

 

From the NTSB report:

 

"the composite material had not been compromised, and the NTSB concluded that the material had failed because it had been stressed beyond its design limit"

Posted

I remember the Airbus with the broken tail. Pilot used max rudder at high airspeed, cycling it left and rigt rapidly, and the fbw actuators tried to give max rudder as he commanded, the actuator force was enough to move the rudder into the airstream enough that the cyclic drag loads broke the tail fin off.

Design safety factors in aviation are extremely low, no more than 5 to 10% strength reserve - more than that is seen as uneccesary weight and hence wasting money. Most modern planes are right on the edge of what is possible in terms of mass optimization. If something unforseen happens, disaster is not far away.

Posted

I remember the Airbus with the broken tail. Pilot used max rudder at high airspeed, cycling it left and rigt rapidly, and the fbw actuators tried to give max rudder as he commanded, the actuator force was enough to move the rudder into the airstream enough that the cyclic drag loads broke the tail fin off.

Design safety factors in aviation are extremely low, no more than 5 to 10% strength reserve - more than that is seen as uneccesary weight and hence wasting money. Most modern planes are right on the edge of what is possible in terms of mass optimization. If something unforseen happens, disaster is not far away.

 

It was on DSTV, I think over the weekend, where they investigate disasters. The tailfin was found almost undamaged. The twp motors broke off and the plane "floated" to the ground like a macabre autumn leaf. Quite terrifying to see that huge plane pancake in their simulation.

Posted (edited)

I remember the Airbus with the broken tail. Pilot used max rudder at high airspeed, cycling it left and rigt rapidly, and the fbw actuators tried to give max rudder as he commanded, the actuator force was enough to move the rudder into the airstream enough that the cyclic drag loads broke the tail fin off.

Design safety factors in aviation are extremely low, no more than 5 to 10% strength reserve - more than that is seen as uneccesary weight and hence wasting money. Most modern planes are right on the edge of what is possible in terms of mass optimization. If something unforseen happens, disaster is not far away.

 

There's been a few - that JAL 747 when the (badly repaired) pressure bulkhead popped and severed all the controls to the tail. Pilots tried their damn best to steer the aircraft with ailerons and flaps/ air brakes but after a while ended up wiping out into a mountain. There was one of two survivors.

 

As I understand it, safety margins are big on aircraft (like 100%) but its that unanticipated circumstances or conditions that cause aircraft to break.

 

Like the Carbon-carbon leading edge of the Space Shuttle Columbia, which was designed to withstand 1000's of degree of heat during re-entry, but not a suitcase-size chunk of insulation foam.

 

That Air Disaster series is fascinating ( I have most of 'em btw), although the human tragedy aspect gets a bit overwhelming. Compulsory viewing for anyone interested in human culture and technology.

 

Edit- typos

Edited by kosmonooit

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Settings My Forum Content My Followed Content Forum Settings Ad Messages My Ads My Favourites My Saved Alerts My Pay Deals Help Logout