venerdì 22 luglio 2011

Decollare al traino con ala rigida



qui le 12 "buone regole" per decollare al traino (in inglese, sorry;)

Since the interest in surface towing (foot launching) an Atos has come up, I thought I would share my experiences of the last three years. I would guess I now have at least forty five foot launched tows under my belt. It's still my preferred method of launching under tow for two reasons. One, I don't have Martin Henry's rig, and two it's so dang easy. Oh, and by the way, I'm 51 years old, so no whining from you younger guys.

Some of this info will be suggestions and some will be absolute "Do Not Deviate". It is assumed that my setup consist of a "V" bridle with a double release. The apex of the "V" is attached to the tow line with a weak link located at the "V". I have a single line over and a single line under the basetube attaching to my LOWER tow loops on my harness. These suggestions are not for aero towing but for winch towing from the surface.

1. Use a double release consisting of a line under and a line over the bar. WHEN FLYING AN ATOS, DO NOT USE A SINGLE LINE UNDER THE BASETUBE. The bottom line should have enough slack as to not touch the basetube during the initial 100 feet of climb. If the bottom line touches you will not be able to make small roll adjustments. You will either be full on or full off with your spoilers. You'll now if it happens as the controls become very jerky and require considerably effort to turn.

2. Do not release the top line too soon. If you do release too soon, and you will sooner or later, go ahead and slightly increase your climb angle to reduce the amount of basetube contact time. The Atos climbs our very quickly and if you were just a bit premature with your top line release, the contact time should be only a few seconds. Again, if you do, the angle of the bottom line will be touching the bottom of the basetube and your back to the situation described in #1. As I'm climbing out I watch the angle of the top line in relation to the basetube. As it begins to touch is when I usually transfer to the bottom line.

3. Be prepared for a weak link break when releasing the top line. Due to the slack in the bottom line, upon release, a shock is transmitted to the weak link. I have had it break during the transition but remedied the problem with a stronger weak link. I try to soften the blow by pulling in a bit, and I mean just a little, or informing the tow driver to reduce tension momentarily. This has not been a problem as of late. The shock can also be reduced by adjusting your "V" bridle (shortening your bottom line) as to have the least amount of slack required to clear the basetube.

4. Use a release that requires one motion to release both lines in an emergency. You don't want to be grasping for two separate releases in an emergency. I think you get the idea.

5. DO NOT LAUNCH WITHOUT FLAPS. I'll say it again, DO NOT LAUNCH WITHOUT FLAPS. Yes, I have done this. The only marginal launches I have experienced have been due to this oversight. You will double your takeoff run at the very least. You can reduce your flap setting if the surface winds are significant. I use a standard mountain launch setting.

6. Crosswind launches while foot launching greatly increase your chances of an incident. Use a wing runner if you must launch. You cannot launch in the same crosswinds that you can while platform towing. It's the price we pay for foot launching Rigids. I have not tried crabbing the wing into the wing while running. You can do that yourself and get back with me on how it went.

7. Lay out at least 300-400 feet of line before beginning your tow. This really dampens the effects of towing on initial climb out. The amount of line that is initially laid out will determine the height at which you will have to release the top line. The longer the line, the more altitude before release, which is a good thing. You are going to have to have a method of communicating with your driver, clearly and effectively. Once you have cleared the ground and are climbing, tell your driver "Good Launch", remember, he's 400 feet down the road.

8. YOU WILL NOT NEED ADDITIONAL TOW PRESSURE ON YOUR INITIAL LAUNCH. Use the same pressure you would use to climb up the line if you were platform towing. Do not start your tow with slack in your tow line, This is not a beach start.

9. HOOK IN! I saw it happen once, not to me. It was not pretty. You will not leave the ground but you will find it.

10. Until you master this method of launching, I would highly recommend that you choose a day day with a little wind. Even 5 mph makes a HUGE difference. In a steady 10mph expect your takeoff run to be around three steps. In a 0 mph with no flaps expect to talk to God and get religion.

11. DO NOT TOW OFF OF YOUR AEROTOW LOOPS. Use the bottom loops on your harness. It's no fun standing on your head while being towed by a vehicle. You will be fine until you climb out, that's when the religion kicks in again.

12. Make your driver tow you. Do not out run your tow vehicle. I dig in and lean back during the first initial steps with a tight line. It works!

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