At last year's Amby Valley meet, I saw a custom built Futaba Tx with 40 channels ! Used for various mixing functions, he said that he could yet do with more !

Interesting...  never heard of that before  Learning something everyday on the forum 

BTW, mixing alone should not require these many channels, right ? Mixing allows various inputs to be "mixed" but fed back through existing channels.  So instead of just transmitting, for example, the signal corresponding to a stick position, they mix signals from various switches, knobs, and sticks (or even programmed responses), and then output signal is "adjusted" on one or more channels before it is transmitted.

Looks like the number of channels required would be more proportional to the number of physical items on the aircraft that need to be controlled independently (like airleron/elev/flaps/retracts/lights/smoke etc), than mixing requirements.

Can't imagine how he needed 40 channels   Would it in any way be a confusion with the Futaba FX-40 "tray-type" radio that has 14 channels ?

http://www.rcuniverse.com/magazine/newproduct.cfm?product_id=1380

Wow! 40  Cannot imagine. I believe they must be using them for photography etc..

40 Channels is just too much of controls! Too much of information / control is bad specially with 3rd person perspective in RC flying.

Lookheed/BAE have been working hard to make much more intuitive flight control 'HUD' ( today they HUD helmet alone cost $1-$3 million  a piece). They would integrate controls for more 'Natural' interface , as smalls as moving panning the camera as the head moves, target lock/menu selection with Iris tracking etc etc..

You may need aux channels for bells and whistles like lights/smoke/bomb-bay but a 8-10 channel radio should be adequate for any sane bird, even soaring gliders with multiple flaps/ailerons.

Slightly off-topic !

One heck of a servo test, using a Futaba FX-40.

Anwar, it is possible  that I heard "14" as "40"  But it looked bigger than the pic. on the Tower Hobbies site. Memories do play tricks, however, and I cannot be categorical on this.

But his quote :" could do with more" remains. Let's try and figure what 14+ channels could/would be required for!

  40 is a really big number. just trying to figure out how can someone control or remember so many channels all together. 

If it is a "tray" type, then most probably this is the case.

BTW, there is also an FX-30 from Robbe/Futaba which may be slightly bigger.  Plus, when placed in a tray, these look huge.

You can get an idea of the size from the last few seconds of this video (this is the first video I saw these radios).

Some people building bigger ships use separate channels for servos when, for example, ailerons use two separate servos. This may be forced by how the servos are mounted, to do precise mixing, or just may be to avoid using Y cables.  So you can end up with 2 channels for ailerons, 2 channels for flaps, one channel each for throttle, rudder, elevator, retracts, smoke, bomb release and a few for different lights, and you can use up 14 channels (if you wanted)   

Of course, most people rarely find needs for over 10 channels, even while building large models.