I’m always amazed when I see a bird flying full speed into a tree, and then suddenly stop and land on a branch. I know they don’t really have a good deal of mass, so their momentum is fairly low, but they do, in fact, have some. And I can’t figure out how they stop so suddenly and with so little swaying, and so little effect on the branches they land on. I guess they must, un-noticed by the naked eye, put on the air brakes first, and then settle down to the branch. And that probably absorbs the majority of their energy and disperses it. But it does seem to be a fantastic feat of physics that they can stop so suddenly. For that matter, it’s pretty amazing that an ant can apparently start and stop without speeding up or slowing down. What is not evident to the naked eye?
They tend to drop onto the branch. So they kinda cut the throttle, have full flaps, and flare right over the spot they want to go, then sorta flop down onto it. At least that’s what I’ve seen.
Well actually, it’s almost right over the branch. There’s a bit of legs forward stuff going on too, so I think the legs absorb a fair amount of the inertia.
The coolest though, is watching pelicans coming in on water. Just like a seaplane.
They brake with their wings. It appears to me that they actually stall their winds just as they touch down just like a three-point aircraft landing. At least ideally it’s just as they touch down. It doesn’t hurt if the stall occurs at a low enough altitude.
I’ve also seen 'em do a kind of ballistic approach when they are flying up onto a branch from the ground - such as when they’re on the footpath and you suddenly scare them. This one’s easier to see - they definitely have a gravity assist where they stop flying when they’re about eye level with the branch, and momentum takes them up and onto it just at the right point in the arc as they start to fall.
Yeah, I’ve seen birds do that up to a telephone pole cross arm. They swoop up, wings almost folded and at the last second spread their wings and land. The amount they need to spread their wings probably depends upon how well they have judged the swoop.
Ants are so small that they have an enormous friction to mass ratio with respect to the ground.
When I was skydiving we called it flaring, basically you change your wing angle to stall, stop all forward motion about 4 " off the ground and step down. In theory of course, birds are almost infinitely better at this than I was.
The cockatoos that land outside our kitchen window every morning and evening certainly have quite an effect on the branches they land on. These birds are big and boofy and have no grace at all, it seems to me they actually use the flexibility of the branches they land on to absorb their momentum - they come in with a real WHACK and bounce around for a while.
Eagle One, this is Eagle Two at Airport Eyrie. Welcome to our airspace. You are cleared to land on Branch One. Be advised there is a crosswind of 2 knots and that Branch One is damp following recent rain.
Eagle Eyrie, this is Eagle One. I am travelling at 55 knots and beginning my descent. I have visual contact with Eyrie and have adjusted my landing gear to account for the dampness.
Eagle One, confirmed - your landing gear is in gripping position. Are you carrying food supplies for Eagle Junior?
Eagle Eyrie - yes, I have sufficient food for the junior inhabitant of Airport Eyrie. I intend to have a fast turn-round and take-off to acquire supplies for the rest of Airport Eyrie.
Eagle One, confirmed. You have priority one and a take-off slot has been reserved for you.
Eagle Eyrie, Eagle Eyrie - there is an obstruction on Branch One ! I am aborting my landing and will go-around.
Eagle One, acknowledge your go-around. Branch One will be cleared immediately (and Eagle Junior will not repeat this offense).
Eagle Eyrie, I am now approaching Branch One. I am switching from full flight power to braking procedure.
Eagle One, prepare for controlled stall. You are correctly lined up on Branch One.
Eagle Eyrie, thank you. Controlled stall now operational and … the Eagle has landed!
Man, birds are awesome.