Speaking only for myself, I like to see some sky between the trees and the airplane -- because small differences in depth are hard to judge at distance. You can't hit the tree with an RC plane when you are trying (and the opposite is also true.)
To put some numbers on it, I would estimate a typical RC approach has a glideslope in the range of 6-10 degrees. I say this because I've developed an autonomous UAV landing system where I can set the exact glideslope angle and 6-7 degrees ends up looking pretty shallow comparatively -- narrow margins with the tree tops on approach compared to typical RC planes landing in the same location. I wish this captured a bit more of the approach, but here is 6.5 degrees glide slope (flown by the computer all the way to touch down.) R. Perry I know you know this, but for the quad-copter jocks, a typical full size airplane approach is closer to 3 degrees or a tad higher to give a little safety margin. I forget what it is coming into a carrier, probably way steeper and way more terrifying!
(You would be right to observe that landing did not have much flare ... the autoland system does flare, but it was a little late on that landing. The main goal is to fly the approach into the ground and stick it for no bounce.)
Many RC designs are very draggy and can do an 8-10 degree glideslope without over speeding. The overwhelming majority of daily flyer airplanes at my club tend to be high power, high drag, with lots of stability margin in order to account for the fact that the pilot isn't in the cockpit feeling every little change immediately. RC planes (the ones that survive for a few flights at least!) tend to be very forgiving and have the ability to power out of some pretty sketchy situations.
I've been told by flight test engineers that pilots tend to be in one of two categories: high gain or low gain. High gain pilots hit the controls fast and hard to put the plane where they want it. They might over do it on the first input, but the also catch it quickly. Low gain pilots tend to be slow and smooth on the controls and let the airplane do the work. I don't mean to say this in a biased sounding way -- from the perspective of flight data, both pilot strategies tend to achieve the objective in about the same amount of time so one approach doesn't necessarily score better than the other; they are just different styles.
This high/low gain difference comes to mind when I'm at the RC field watching landings. Some pilots are definitely high gain. They are working the elevator and ailerons hard all the way to touch down. Some pilots are super gentle on the controls ... they try to trim for target approach speed, slowly change throttle settings, use the elevator to correct but not force -- let the airplane do the work rather than do the work themselves. I don't think either approach wins with respect to who has a better chance of hitting the touch down spot. At my club high 5's are in order if you keep the whole landing on our rather small runway and don't overrun (or touch down on) the grass.
So wish me luck, later today we are heading out to try to re-maiden our 14' 1/2 scale X-56 project powered by twin electric ducted fans.
