Glide ratio

[jupija 0]

have a mojo 220, my wing load is from 0,67 to 0,75 - it depends what i have on me- what is bothering me is glide ratio with brakes on 25%, 50% or 75%. Do u just devide % from normal GR or is there some other formula how to get this knoledge.

lets say there r no wind conditions, u jump and throw from 100 m high object, evryth. is O.K. unblock the brakes and just move streight on with no turns with brakes not blocked at all - how much ground do u think one would cover.

And from your experiance how is it to land with 50% brakes - is it as hard to brake bones or u just rool over to compenzate the hit.

[jmidgley 0]

Take any object that glides. If it's possible to alter it's speed, it will have a lowest speed (at which it stalls) and a maximum speed (which might be a design limit, or imposed by drag, or simpy 'no brakes' in the case of ram air canopies - ignoring strategies for deforming the leading edge). At each of these speeds the glider will sink at a certain rate (the numbers change for different wing-loadings, of course). At each speed in between, having settled to that speed, the glider will sink at a certain rate. If you plot all those speed/sink rate points, you get a polar curve, which looks like a lop-sided, upside down 'U'.
At one point, not far from stalling speed on a ram -air, you'll find 'minimum sink'. Well worth finding this point. Further along the curve (ie faster) you'll find a point where the distance covered is maximised with respect to the sink rate - 'maximum glide'. It may not be with brakes fully up, but probably quite close. Any faster and you'll cover *less* ground.
Figures like '50%' are going to be impossible to judge in practice, but if 'min sink' happens to be a surviveable descent rate, PLF or otherwise, it would be as well to get a feel for where it is on your canopy.
Don't know whether that answers your q, but hey.
John