All it boils down to is simple aerodynamics. All wings have a maximum glide airspeed and a minimum decent airspeed. The two largest contributing factors are induced drag and parasite drag. The later, "parasite drag" has many sources while flying a parachute. The largest and easiest to minimize is your frontal surface area.(Your body) Make that beeotch small. The other, "induced drag" is a byproduct of lift and inherent to all lift producing surfaces. If you look at any wing flown at various airspeeds from their respective stall point to their bat out off hell front riser dive their are two standout airspeeds(when graphed) that both parasite and induced drag are minimized. These airspeeds directly equate to minimum rate of decent airspeed(usually the slower of the two airspeeds) and maximum glide airspeed(the faster). One will give you maximum time aloft(minimum rate of decent a/s) and the other will give you maximum penetration or distance over the ground(maximum glide airspeed). This being said you can see how in skydiving there are huge varibles from jumper to jumper when it comes to body size/shape, weight, line types, deployment system, slider, and so on. That all being said, you can see how without a team of engineers figuring out every type of flight envelope imaginable for every parachute on the market and real time airspeed indicators not widely proliferated, this is a daunting and futile task. So this is how I break it down. Depending on how strong the winds are you will most likely want to use your minimum rate of decent airspeed(brakes) when upwind and let the wind aid your return. When downwind you will want to use your max glide a/s(slight rears) because this will minimize induced drag that using brakes will cause allowing you to fly flatter a little faster. Since parasite drag increases dramatically with airspeed you need to keep in mind that putting down the "doughnut" may become extremely handy in this situation. All this being said it will vary from canopy to canopy. But I do believe Ian is dead nuts on. Or I may be completely full of shit. Never forget winds change aloft. Not just when planning a jump run, but remember this when even a few thousand feet above the ground. The winds can easily be 90 degrees off surface winds and even 180 degrees out. On a side note: You guys need to stop bitching at each other and getting off topic. I have learned alot from these forums, but I have also learned that sometimes it turns into a druken pissing contest around here. Needs to stop.