Mark Stull

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cpd

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Jul 24, 2008
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Its people like George that may have prevented Mark from sharing his last design with us...........

Chris
 

autoreply

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Rotterdam, Netherlands
I was even threatened to be kicked out of the board if I say any more in the private message from Jake. I saved it because I knew where this whole thing was going, I'm posting it in full below.
Now Mark is dead.
As the name implies (PRIVATE message), those are private, not public and thus I've removed them from your post.

Mark has received lots of criticism on his designs by many people and has politely and to the point replied to all of us.

Personally, your reply leaves a bit of a sour aftertaste to me.
 

revkev6

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Joined
Mar 9, 2010
Messages
425
Location
massachusetts
Well George, the design you were criticizing then was not the one that killed him...

-Dana

Earthlings: Send more probes. The last one was delicious!
Didn't mark actually say that was one of his favorite designs to fly??

Even though george may have meant well, he comes across rather confrontational. I can only hope it is the "internet disease" where people forget normal rules of etiquette because things are so anonymous. Fortunately for us, Mark did not have this problem and freely shared ideas, failures and motivation with a grace that made us all respect him!

I think we can all agree that we envy the way Mark was able to live out his dreams. Beyond all his aeronautical experience, there is a great wisdom to be taken from that!

rest in peace mark, I hope your happy with your current study of the efficiency of ornithoptors!
 
Joined
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What anonymous internet disease are you talking about, My user name is my real name, I am in the airplane building business and with every post I make I put my reputation on line, my info from here leads right down to my home phone and address , which by the way happens to be in your neighborhood. You can come to check it out
 

BobDaly

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Apr 8, 2011
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83
Location
Albany, NY
I believe George S's criticism of Mark's earlier successful design is in error. He suggests that design lacked a sufficient drag truss. I beg to differ. The wing is external wire braced. The wires react not only torsion but chordwise loads. George's insistence on pinned joints is also incorrect. The analysis of trusses is made simpler if the connections are assumed to be pinned joints. If the truss members are long and slender the forces involved can usually be treated as entirely axial and any bending or shear forces are negligible. I note that the beautiful Himax George built has a wing drag truss where the joints are glued.
 
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WonderousMountain

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Clatsop, Or
If the truss is usable in tension only, then the size of the members can be rather small, even wires, but if compression is to be seen then you wouldn't want slender members at all, and the use of pinned joints can be very useful. At the root, Mark used aluminum strip, which was more than strong enough (I did calcs), two members were used like wires, so it was in tension, not compression. Not being braided wire, they could have bent in compression, but I don't think that happened, due to their being almost no slack in the system. Any bowing would be minimal.


While the straps were only at the root, it's clearly seen in a later post that it was externally braced futher out. George, did you know it was to be externally braced when you commented, or do you still hold that the external bracing was insufficient?

Didn't do any rib/compression strut calculation, but geometrically they were in optimum standard position.

These comments do not apply to his ill fated design, which I have no information on.
 
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bmcj

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Just to repeat Dana's observation, George's critique may have been addressing Mark's earlier design, not the most recent one Mark was killed in. I believe the latest two comments speak to Mark's most recent plane.
 

BobDaly

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If compression is to be seen then you wouldn't want slender members at all
Well, we may be arguing semantics here so to use a more precise term, if your compression members aren't long columns then your wing truss is overbuilt. The failure mode for such a member should be buckling.

I believe Mark only added the crossed straps when he discovered his wing to be out of square during construction. He could have trued the wing during rigging by adjusting the flying/landing wire tensions, though I understand that's difficult and time consuming and prefer Mark's solution.
 

WonderousMountain

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Well, we may be arguing semantics here so to use a more precise term, if your compression members aren't long columns then your wing truss is overbuilt. The failure mode for such a member should be buckling.
Do not agree, won't elaborate here.

Blessings,

Mountain
 
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