Leaping from tree to tree is easy. I encountered something in a game
which should be rather harder.
I have recently run the Project Medusa adventure for the
Outgunned RPG, for Whartson Hall. It's not a great adventure in
several respects, but it does a decent job of showing off the system.
However, in the climactic scenes, when our heroes have stolen a
helicopter to chase the villain:
When all Need boxes are full, the HEROES manage to reach STAMOS’
helicopter, only one of them can try to jump onto the other aircraft
[Critical Action Roll]. If they succeed, they also gain 1
Adrenaline.
Jump onto the other helicopter. Hmm.
Well, this game is inspired by 1980s action films, so the helicopter
is inevitably going to be a Bell 206, a JetRanger or a LongRanger.
That gives me a source for dimensions.
Assume our hero enters the fray with their hands at (just below) rotor
height, and grabs a skid as they fall past. That gives them the
greatest possible distance to drop.
(I modified this and the diagrams below from FOX 52's image at
Wikimedia
Commons,
which is CC-BY-SA 4.0, and therefore so is this blog post. All image
links are to SVG files.)
The JetRanger has a total height from skids to rotor of 2.908m. so
neglecting air resistance that will be a maximum time of flight of
0.770s.
The rotor has a diameter of 10.16m and, from a less reliable source, a
skid width of 1.95m. Halving the difference to get the horizontal
distance from blade tip to skid, our hero has to traverse 4.10m in
that 0.770s. So they must be travelling at a minimum horizontal speed
of 5.33m/s (11.9 mph).
They are leaping from another helicopter, and probably can't easily
achieve an upward angle. If they have to pass under both rotor discs
from a horizontal start (assume they've already climbed onto the cabin
roof), they'll need to go faster, as the vertical drop will take the
same time but the distance to be traversed in that time is doubled. So
the required speed becomes 10.66m/s or about 24mph.
Even this is within the range of an Olympic runner, but they'd
probably need more space to get up to speed than a helicopter cabin
affords (though one of the players suggested a long plank for a
run-up). A recoilless cannon (exhausting countermass out of the other
side of the cabin, because the momentum transfer of launching a hero
at this speed would cause problems in flight) seems more workable.
If the launching helicopter can be briefly tilted away from the target
we can potentially cut the necessary speed further, as the apex of the
jump can lie within the area of the target's rotor disc. (I assume the
target will not cooperate by also tilting away.) However, this will
need more energy, and thus speed, for the initial height gain.
Of course by far the safest option requires cooperation from below.
(Bouncing spring image by Delapouite via game-icons.net, CC-BY 3.0.)