Talk:King post

Crown Post

Unfortunately there is a serious error in this page and the illustration of the crown post roof is misleading. Crown post roofs predate king post roofs and are not a development of them. They also serve a quite different function. Crown posts were used with common rater roofs, i.e. roofs without side pulrins. The purpose of the crown post and associated collar plate, which it supports and is braced to, is to ensure longitudinal stability of the roof. Without it there would be a tendency for racking. King posts are associated with side purlin roofs that post-date common rafter roofs. The king post is an integral part of the frame that supports the purlins. Hansdampf 08:52, 7 October 2007 (UTC)

I was curious about this but don't really know my architectural terms. Can you find a reference? - PennySpender1983 (talk) 00:01, 7 August 2008 (UTC)

Is the king post a compression or tension element?

I think the diagram of forces shows the King Post itself in the wrong color. It should be in compression, not tension. (ChrisHibbert (talk) 19:49, 6 August 2008 (UTC))

Here is a reference for the king post being a tension element. (Historical American Engineering Record (1976). "Trusses: A Study by the Historical American Engineering Record" (pdf). National Park Service.) The diagram of the king post truss (on the top right) shows the vertical member as a thin line and the compression members are thick lines and tension members are thin lines (just as I drew it). The text on the left side explains this.

Additionally, the vertical member will be a zero force member unless there is a load placed at that point. Imagine a ceiling fan hanging beneath or the deck of the bridge placing a load there. - PennySpender1983 (talk) 00:01, 7 August 2008 (UTC)

That poster is now here. - Eponymous-Archon (talk) 19:49, 5 April 2016 (UTC)

merge part of this page?

I am wondering about merging most of the information about the architectural king post with King post truss. This article is basically a disambiguation page of basic definitions about what a king post is, but then the architectural sections go on to discuss trusses and comparisons with other similar framing members. Jim Derby (talk) 02:37, 19 January 2013 (UTC)

That's a thought, what would it leave behind? - Ahunt (talk) 18:34, 19 January 2013 (UTC)

Really, I think this page could become a disambiguation page and the definitions of a king post can be presented in each relevant article. Jim Derby (talk) 01:12, 22 January 2013 (UTC)

Where would that leave the aircraft king posts section? - Ahunt (talk) 01:20, 22 January 2013 (UTC)

In Flying wires where it is currently absent. Jim Derby (talk) 12:38, 24 January 2013 (UTC)

Yup it could be moved there! - Ahunt (talk) 16:32, 24 January 2013 (UTC)

conflicting information on the page

There is a clear conflict between the information shown in the diagram "A diagram of the parts of a king post truss", which shows the rafter or diagonal in compression and the tie beam supported at its end, and the situation shown in the photo "DFE Ascender III-C ultralight aircraft showing its king post above the wing", where clearly the 'rafters' are in tension since they are wires! Furthermore, the support is in the centre and the load at the extremities of the wire, the exact opposite of the other situation. I don't know about terminology, but even if these two posts have the same name, they have a completely different function, and that should be made clear in the article.

Oh, and the comment earlier in this talk page about there being no load to put tension into the king post unless an external load is applied is also wrong. The self-weight of the tie beam is the whole point! The idea in such a situation is to stop the tie beam deflecting downwards through its own weight. — Preceding unsigned comment added by 88.97.62.77 (talk) 13:13, 28 December 2014 (UTC)

Thanks for your note here. In the case of the "diagram of the parts of a king post truss" the loads are normally applied at the ends of the structure putting the king post in tension. The aircraft use is reversed when it is on the ground, being in compression, but the kingpost takes no load at all in positive-g flight. It is the bottom wires that are "flight wires" and the top wires are "ground wires". I have added a clarification. - Ahunt (talk) 13:23, 28 December 2014 (UTC)

The article now says "On the ground the aircraft kingpost is in tension" but as you say, clearly it must be in compression since it's supporting a load with cables suspended below it? 84.219.169.191 (talk) 17:20, 8 January 2015 (UTC)

Yes, that "clarification" was anything but. A kingpost in tension? Andy Dingley (talk) 17:48, 8 January 2015 (UTC)

Confusing sentence

In the first section, there's this sentence: "Said to be the oldest and simplest truss, the oldest surviving roof truss in the world built between 548 and 565 is a king post truss in Saint Catherine's Monastery, Egypt." It's very confusing as written. I think what it's meant to say is that the king post truss is "said to be the oldest and simplest", and then go on to note the oldest surviving example in Egypt. Do I have that right? - Eponymous-Archon (talk) 19:58, 5 April 2016 (UTC)

Yes, I think that is correct. Feel free to fix it. - Ahunt (talk) 21:45, 5 April 2016 (UTC)

OK, done, along with some other moving around. I think now that the sections "Architecture" and "King post truss" could be usefully combined. Thoughts? - Eponymous-Archon (talk) 19:39, 6 April 2016 (UTC)

I agree with that idea! - Ahunt (talk) 18:06, 7 April 2016 (UTC)