In the old days this was called P-51 time. (Parker 51) 8) For you youngsters, Parker made pens.
Charlie, that's what I was thinking, too. Thanks for bringing it up.
I keep looking at that Javron box structure too, doing my best to imagine the forces.
Actually it is the compression ribs which control the twist. The ribs only hold the fabric shape.
Hate to be the critic but you should go over the math some more. The struts are way to few and far between to offer much of any resisting to twist / buckling of the spars.Actually it is the compression ribs which control the twist. The ribs only hold the fabric shape.
This picture?Hate to be the critic but you should go over the math some more. The struts are way to few and far between to offer much of any resisting to twist / buckling of the spars.
The testing RV did is pretty darn close to the numbers that Piper's style of riveted ribs as well.
If you refer back to the image that Steve P posted of a CC failed rear spar you will note the total buckling is between ribs. If the added support of what was designed in for the 2000# gross weight had been added that buckling might well have been much different if not even failed.
This picture?
The buckling was prevented at the compression rib. The buckling which did occur was caused by an outside impact force.
Charlie, You know that the engineering is done for the flight loads, not crash damaging loads. You are mixing apples and oranges.Air loads or impact, it is still a single point failure. Looks to me it is very clear nothing prevented or reduced any buckling. The failure was not spread out as should be if the engineering were closer to what is should be.
No, no I am not. A simple ground loop should not destroy a major component of an aircraft. There have been in flight failures of Cub wings dating back many decades.Charlie, You know that the engineering is done for the flight loads, not crash damaging loads. You are mixing apples and oranges.
There have been in flight failures of Cub wings dating back many decades.
.
I have cold- straightened spars. The amount of force that takes is stunning!
That because you didn’t heat it first and reheat treat it before straitening it. Bringing it to it’s annealed (soft) condition temporarily. (I am not a fan of doing this either..) just replace spar
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No, no I am not. A simple ground loop should not destroy a major component of an aircraft. There have been in flight failures of Cub wings dating back many decades.
A fuselage should not collapse around it's occupants with mild mishaps. There are to many that have done so.
I have spent my life working on survivability of structures. The plane I am building is just one example showing the differences in structure to achieve the goal. It is not for everyone but I believe in walking away, even if one might be limping.
Single point failures should have been designed out of these structures long ago. Some companies have addressed a number of the issues, but the severity of that spar failure from what is not even a crash makes it clear that some have not.
The Cub fuselages have needed quite a few added braces which most people do, kudos to them since they care and understand. But no one has addressed failure of landing gear mount points, Why? Safety cables, Why? Fix the problem.
The main reason I am building a look alike is I have no desire to even consider the lack of survivability in my original J4.
Someone might want to continue with the restoration of my original plane but it is not me.
On my current build some people feel my wings are a copy of the RV series of wings, they are not. Wings should not buckle in flight especially when the fix does not even add weight. End
Charlie, I agree with you that should not destroy, should not collapse, should have been designed, should not buckle in flight ought to be designed into an airplane. However show me in CAR 3 and CAR 4 where it says should not. There are specific parameters spelled out, should not is not among them. FAR 23 was an attempt to correct the deficiencies of those earlier regulations. That is just one reason why the costs of certifying a new design have risen as it has.No, no I am not. A simple ground loop should not destroy a major component of an aircraft. There have been in flight failures of Cub wings dating back many decades.
A fuselage should not collapse around it's occupants with mild mishaps. There are to many that have done so.
I have spent my life working on survivability of structures. The plane I am building is just one example showing the differences in structure to achieve the goal. It is not for everyone but I believe in walking away, even if one might be limping.
Single point failures should have been designed out of these structures long ago. Some companies have addressed a number of the issues, but the severity of that spar failure from what is not even a crash makes it clear that some have not.
The Cub fuselages have needed quite a few added braces which most people do, kudos to them since they care and understand. But no one has addressed failure of landing gear mount points, Why? Safety cables, Why? Fix the problem.
The main reason I am building a look alike is I have no desire to even consider the lack of survivability in my original J4.
Someone might want to continue with the restoration of my original plane but it is not me.
On my current build some people feel my wings are a copy of the RV series of wings, they are not. Wings should not buckle in flight especially when the fix does not even add weight. End