Feb 11, 2002, 8:42 PM
Post #1 of 10
Dealing w/ Turbulence (Hey Kris!)
Definition: A condition of fluid flow in which the flow is not smooth. The speed and the direction of the flow changes rapidly.
The best way to deal with turbulence is to avoid it. Become adept at predicting where turbulence is likely to be encountered and avoid those areas. Down wind of buildings and other obstacles is a prime area for turbulence. As the wind flows over the obstacles, it becomes turbulent, similar to water flowing over a rock. A rule of thumb is turbulence can be found up to 100 times the height of an obstacle. If you fly behind another canopy, you can encounter the wingtip vortices coming off the wing tips and he disturbed air behind it. Behind a running aircraft, the propeler(s) create a tremendous amount of turbulence. Dark areas (asphalt, or any area darker than the surrounding area) on warm days soak up the heat from the sun and release it into the atmosphere, causing up drafts. Flying over a dark area and then a light area or vice versus it is possible to encounter turbulence. Thunderstorms will bring gusty, turbulent winds with them.
Before each jump, look at the landing area, check the winds and look for areas that will likely contain turbulence. Plan your approach to avoid these areas. Have a back up plan in case of traffic, long spot, etc. Be prepared to account for turbulence in a new landing approach if the wind changes.
If you find yourself in turbulence on final approach, fly through it at full flight (toggles all the way up), making small toggle inputs to keep the canopy flying into the wind. The more forward speed the canopy has, the more internal ram air pressure inside the canopy. The higher the internal pressure of the canopy, the more resistant to collapse it is. If you canopy buckles or folds, use the toggles to keep it flying straight, and prepare to PLF. Don’t ever give up.
Do what you got to do. Wing loading and speed is your friend in turbulence. If you hit a rotor as you are coming off the doubles and it is dropping you in, you don't have any choice but to dig out w/ the toggles. Another reason why hooking higher is safer. My VX loaded at 3.1 had never come close to folding or bucking even a little.
The Merlin I flew (Very fast twin turbo-prop w/ a very high wing loading) flys through turbulnce w/o any effect on the sirplane, that would have the Piper J3 cub I flew (85 hp single engine fabric covered very light wing loading) going all over the sky.
I took his question to mean "if I do everything I can to avoid turbulence while hook turning, but hit some anyway, what do you suggest?" Like I said, the best way to handle turbulence is to avoid it, but that isn't always possible.
I agree with the advice about flying fast and smooth in turbulence (so do PD here) but it does surprise me how many highly experienced think you should fly at half brakes. Heck there was even an official DZ notice at Eloy about a year ago (not sure if it's still there) advising half brakes!
"I was taught that in turbulance you fly in 1/4 brakes to increase stability. Is it wrong? "
If you find yourself in turbulence on final approach, fly through it at full flight (toggles all the way up), making small toggle inputs to keep the canopy flying into the wind. The more forward speed the canopy has, the more internal ram air pressure inside the canopy. The higher the internal pressure of the canopy, the more resistant to collapse it is.
In turbulence, the higher the internal pressure of the canopy, the more rigid it is and therefore less likely to collapse.