Thruster87 Posted October 12, 2011 Share Posted October 12, 2011 Link to comment Share on other sites More sharing options...
Thruster87 Posted October 12, 2011 Author Share Posted October 12, 2011 Intersting the way the rivets just unzipped Cheers Link to comment Share on other sites More sharing options...
Guest Swanny Posted October 12, 2011 Share Posted October 12, 2011 They are tough little aeroplanes Link to comment Share on other sites More sharing options...
Virago Posted October 12, 2011 Share Posted October 12, 2011 Those unzipped rivets may just have absorbed some of the "sudden stop" energy and helped protect the occupants. It is interesting to see that the engine mount pins remained attached to the longerons. I had thought they might be a weak point but obviously not. I agree with Swanny ... these are tough little aeroplanes. John. Link to comment Share on other sites More sharing options...
facthunter Posted October 12, 2011 Share Posted October 12, 2011 They are tested in"wheel" situations, are they? Nev 1 Link to comment Share on other sites More sharing options...
pete8862 Posted October 12, 2011 Share Posted October 12, 2011 Can anyone tell me what the engine is? Pete Link to comment Share on other sites More sharing options...
Tomo Posted October 12, 2011 Share Posted October 12, 2011 Can anyone tell me what the engine is?Pete Jabiru 2200 Link to comment Share on other sites More sharing options...
Litespeed Posted October 12, 2011 Share Posted October 12, 2011 Can we see some more detailed photos please. A great example of real world testing, much can be learned on design for safety with this Morgan. Would really like to see the interior and wings in detail to see how they performed. Phil Link to comment Share on other sites More sharing options...
Guernsey Posted October 12, 2011 Share Posted October 12, 2011 The photos you are requesting have been on this site but I can't remember the posting. Ian may be able to help however he may have deleted them. Alan. Link to comment Share on other sites More sharing options...
av8vfr Posted October 12, 2011 Share Posted October 12, 2011 See post 104.... http://www.recreationalflying.com/threads/merged-0ld-bar-incident-at-taree.28587/page-6 Link to comment Share on other sites More sharing options...
Thruster87 Posted October 12, 2011 Author Share Posted October 12, 2011 The rivets should NOT unzip like they did,the parent metal should have torn.When we tested our rivet spacing requirements on samples at tech they always tore the parent material rather then the rivets if done correctly.Cheers Link to comment Share on other sites More sharing options...
Tomo Posted October 12, 2011 Share Posted October 12, 2011 Don't quote me on this, but you'll probably find it is only a cover for the fuel tank and not a structural part. Link to comment Share on other sites More sharing options...
facthunter Posted October 13, 2011 Share Posted October 13, 2011 It's a steel truss frame, and the panel would only get loaded if the frame was deformed or impacted some way or other. To assess the strength of an aircraft in a collision situation the deformation of the other structure would have a bearing on the damage to the aircraft. When it crumples, and moves, it reduces the damage to the plane as it decelerates more slowly. Helps to reduce the injury to occupants also. Nev 1 Link to comment Share on other sites More sharing options...
Thruster87 Posted October 13, 2011 Author Share Posted October 13, 2011 It's a steel truss frame, and the panel would only get loaded if the frame was deformed or impacted some way or other.To assess the strength of an aircraft in a collision situation the deformation of the other structure would have a bearing on the damage to the aircraft. When it crumples, and moves, it reduces the damage to the plane as it decelerates more slowly. Helps to reduce the injury to occupants also. Nev Isn't the structure on the sierra a semi-monocoque and all 6061T6 ? From their web page[The Cheetah Sierra 200 is an all metal 2 seat high performance aircraft that uses a simple aluminium tube, alumminium sheet and pop rivet construction method. The main support frame that holds the undercarriage, pilot and wings to the fuselage is a welded steel tube frame.] So the skins are load carrying. Maybe the type of pop rivets used are not strong enough. Cheers Link to comment Share on other sites More sharing options...
turboplanner Posted October 13, 2011 Share Posted October 13, 2011 You could have fooled me Thruster, I saw a triangulated space frame when we were discussing escape methods. The manufacturer would confirm if he stressed the top panel, But I'd be putting my money, if pop rivets are involved, on a tank cover only. Link to comment Share on other sites More sharing options...
Thruster87 Posted October 13, 2011 Author Share Posted October 13, 2011 Looking at the pic What does the lower longeron attach to other then the firewall rim? What supports the longeron from just bending if you say the skin doesn't act as part of the structure, would it be the same if it was fabric covered. I'm not talking about the area where the U/C and wings attach only the nose section. Cheers Link to comment Share on other sites More sharing options...
facthunter Posted October 13, 2011 Share Posted October 13, 2011 It could be aluminium. When I said steel I wasn't sure. Whatever it is, it is a tube frame with pop rivetted gussetts at the joins. (essentially a triangulated space frame) In principle there is nothing particularly unusual about that. Nev Link to comment Share on other sites More sharing options...
Virago Posted October 13, 2011 Share Posted October 13, 2011 The upper and lower longerons join to uprights and diagonals by pop riveted gussets and also the outside skin. The whole aircraft is basically pop rivetted except for the main spar which has solid rivets. This makes for quick and easy construction but it's still a strong little plane. That was quite a thump it received and I'm surprised it held together as well as it did! Link to comment Share on other sites More sharing options...
facthunter Posted October 13, 2011 Share Posted October 13, 2011 Yes I'd seen the spar attach part, and wasn't sure of the other. Thanks for sorting that out Ign. Slarti bent one and the fuse stood up well. Nev Link to comment Share on other sites More sharing options...
Thruster87 Posted October 13, 2011 Author Share Posted October 13, 2011 Rivet line unzipping like that, still does not seem OK to me for what ever reason.Is there a structures sheety on the forums who would care to comment. Cheers Link to comment Share on other sites More sharing options...
turboplanner Posted October 13, 2011 Share Posted October 13, 2011 Thruster, this is not a good one to analyse - a brick wall would tell a better story. It's quite possible the rivet shear is due to localised impact with a ferris wheel tube, so the shearing could even be in tension. Link to comment Share on other sites More sharing options...
Thruster87 Posted October 13, 2011 Author Share Posted October 13, 2011 What in heavens name are you going on about turbo.One moment you are saying NOT to analyse then in the same breath you analyse the reasons the rivets are shearing [maybe you do or don't have the technical background to understand aircraft structures or is there another agender].All I'm saying is riveted joints in aviation should NOT unzip for what ever reason.If they do unzip you need to ask why. That's how we improve safety. Cheers Link to comment Share on other sites More sharing options...
turboplanner Posted October 13, 2011 Share Posted October 13, 2011 No agenda at all, just technical. The only reference to the brick wall was to simulate an even impact face. This one didn't have it which was why the pilot and passenger didn't die from brain crush. However for the same reason, you have to be careful about drawing conclusions because, say, the riveted section area happened to cop the full brunt of a localised ferris wheel pipe. Traditional rivetted joints in aviation are not pop rivets, and I agree, aviation rivets securing a mononcocque design should never fail or pull out, there should be broken lumps f the monococque everywhere. On the other hand, the weakest area of a fuel tank cover might be hollow pop rivets, and if so they would go first so not unexpected in this case. Link to comment Share on other sites More sharing options...
facthunter Posted October 13, 2011 Share Posted October 13, 2011 It's pretty hard to tell from a picture. It's likely that the rivets have not sheared but the panel has peeled off over the rivet heads. That panel would not be a structural member in the strictest sense (I would imagine) Just a cover. The relevant comment that the ferris wheel was a yielding structure that deformed more than the aircraft, thus reducing the damage to the plane, and the occupants, is significant. Nev 1 Link to comment Share on other sites More sharing options...
Virago Posted October 14, 2011 Share Posted October 14, 2011 I recall the comments of "shock horror" when Victa produced their pop rivetted Airtourer back in the early sixties. Many of these classic planes are still flying nearly 50 years later. Having learned to fly on one (VH-APV which was destroyed in Cyclone Tracy) I have no issue with aviation type pop rivets being used, particularly in homebuilt aircraft. Link to comment Share on other sites More sharing options...
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