I am starting this as a new thread though I suppose it could go under 'how does a trumpet work?; because it is a related question.
A month or so ago, there was a thread titled "Hidden Slot" in which there was a great deal of discussion about partials, harmonics, overtones, open and closed tube standing waves, and other acoustic concepts. There was mention of the effect of conical bore vs cylindrical bore, and even the impedance that occurs at the bell outlet which contributes to the creation of the standing wave and the "equivalent" (my term) length of a piece of conical tubing to similar cylindrical tubing.
The reason that I mention this is that the other night I saw a TV program about music around the world. There is a gal name Diane Bish who travels around the world playing different organs. On this program she was playing a new organ in Ft. Lauderdale, FL. In addition to the regular array of vertical pipes which have the slot at the base, there was another array of horizontal pipes that were used to simulate trumpet sounds. I noticed that when those pipes were played, they still had a distinctive organ sound - they did not really sound like trumpets. At the same time, I noticed that the pipes were purely conical - not cylindrical like the vertical pipes. Also, I did not notice a slot in them like the vertical ones have. I was wondering three things: (1) Was it a deliberate design feature to make the pipes so that they would retain the organ-like sound? (with just a hint of trumpet sound). If so, was it really necessary to add a whole set of special pipes for this sound? I have heard other organs that could produce a simulated trumpet sound without the extra pipes. Or, were these pipes just for show? Or (2), were they really trying for a trumpet-like sound and simply could not make it any closer? If this is the case, why would they keep the pipes purely conical and not form a bell at the end like a trumpet has? Also, I assume that these organs play using compressed air in some way but I would guess that they blow over the ends of the pipes like one would blow over a series of partially-filled bottles to make different tones. So, that action would not simulate the action of a mouthpiece, I would think - hence the lack of the trumpet tone. Would it not be possible to make a mechanical device to act like human lips on a mouthpiece to form the standing wave? Perhaps it would not be perfect but it should create a sound closer to a trumpet than this organ produced; and (3) in either case is the apparent number of pipes really required? The camera did not focus on the horizontal pipes long enough or close enough to actually count the number but my best guess is that there were close to 100 of those pipes. That is more than the keys on a piano. Are those pipes supposed to cover the entire range of all brass - or maybe all wind - instruments? If so, can they approximate the sounds of clarinets, saxophones, flutes, too? Maybe that is why they do not have bells on the ends. But that raises another question. Would it be possible to make the pipes each play more than one note but making them like the early trumpets - with either sliding bells or air holes that can be covered by "fingers"?
So, since there are some here (Rowuk?) that have experience in organ design, are there any particular answers to these questions or is it like architecture - it is all in the eye of the designer? Just curious.