Hooknswoop

This is really getting silly. JP you are wrong. You have stopped addressing the issue and sound like a little kid. Wrong. Again, after discussing this with the designer and builder of the control system, this is not how the system works. You are wrong. Again, you are wrong. The E-stop does not reduce the power gradually. Again, you are wrong. We do not fly in the tunnel with the louver doors open 100%. The E-stop effectively simulates a power outage. Again, you are wrong. At sit-fly speeds, during a power failure, the wind speed will slow down slow enough that the flyer will have plenty of time to transition to either their belly or back and fly to the net. One of our instructors will do 3 or 4 back loops, after the throttle has been brought to zero, which will, again, slow the wind faster than a power outage. Again, you are wrong, that is not how the system works. The fans are slowed faster with the throttle being reduced to zero than they would be during a power outage. Nope they are almost identical, with the e-stop resulting in a slightly quicker wind speed reduction. The difference is not significant. Clearly you do not know the systems as well as you think you do, as I have shown that you are completely wrong as to how they function. Awfully arrogant statement, especially after I have shown that your knowledge of the systems isn’t nearly what you think it is. That’s funny, since I am able to fly up to the turn fans, back down to the net, stop, and then back out the door with the throttle at zero, which, again, means the winds speed is stopping a lot faster than it would during a power outage. Which tunnel do you work at, or is your profile not updated? Derek

Next time I talk to Bill, I'll ask. At SVCO, the doors can be opened without power. Derek

“So, Paulipod & JP, please stop trying to convince our clients that they are at risk” “how quickly will the air go from 120MPH to 0” You may not have intended it, but that is exactly how it came across. I have no idea why the wind speed would decrease quicker at Bedford than at SVCO. I don’t even know that it does. What I do know is that it doesn’t decrease quickly or instantly if the power grid fails at SVCO. I have explained that I am able to fly after the throttle is reduced to zero, and that the wind speed slows down faster with the throttle than during a power grid failure. This remains undisputed. From looking at some pictures, I am curious what type of propeller your tunnel uses, fixed or variable pitch? How many blades? What material is it made from? How much does it weigh? What type of motor powers it? SVCO and Bedford are very different tunnels and the wind flow reaction to a power outage is obviously very different. It would be interesting to compare the differences in rotating mass, air speeds through the air paths, air volume, and how the different drive systems react to a power loss. Clearly they are very different tunnels. Derek

I know I said I wouldn’t say anything else, but I just got off the phone with the company that designed and built the control system for SVCO, discussing other issues. Since I had them on the line, I brought this question up. The fastest way to stop the wind is to either take the throttle to zero or hit the stop soft key on the screen. At that point, the motors are generating power, which is dissipated by the VFD’s through resistors converting the power to heat. This acts to brakes the motors or slow them down faster than if they were simply disconnected from the VFD’s. The next slower way for the wind to stop is to hit the e-stop. This stops power to the motors instantaneously. They are free to wind down without the braking action caused by converting the energy they are producing to heat though the VFD’s. The slowest way for the wind to stop is if the incoming power grid fails. The VFD’s sense the loss of power, use residue power to soften the power loss, keeping the motors going as long as possible and allowing the motors to wind down without the braking action caused by the VFD’s. It takes about 15 seconds for the wind to reach 30-mph after taking the throttle from 90% to zero. It takes about 45 seconds for the wind to reach 30-mph using the e-stop from 90%. It would take even longer for the wind to reach 30-mph from 90% if the power grid failed. I am able to hop in, pop up to the bottom of the turn vanes (about 40-feeet), come back down, stop, and back out the door all after the throttle has been reduced from 84% to zero. If the power grid were to fail, there would be more wind, longer, since the braking action of the VFD’s wouldn’t happen. You would not crash into the net. So there you have it. Testimonials from Instructors that have been flying when the tunnel shut down, testimonials from flying in the tunnel after the wind has been cut off, and information from the designer of the system. If this doesn’t convince everyone that you are in no danger in the event of a power grid failure while flying at Skyventure Colorado, then I do not know what will. So, Paulipod & JP, please stop trying to convince our clients that they are at risk. Now I am going to go put on my snowboarding stuff and see of my street is steep enough to board down since there is 2 feet of snow out there. Derek

Then can you explain why the Kw indication goes to zero in about 1.5 seconds using the throttle and immediately using the e-stop? To clarify, the power consumption goes to zero faster using the e-stop, but it takes more than double the time for the wind to reach 30-mph. that doesn't make sense to me at all. I would think that you would want to have the wind stop as fast as possible in an emergency situation, not have the software bring the wind speed down very slowly when the e-stop is pressed. If you needed the wind to slow down slowly, you could simply use the throttle. "Emergency Stop" and reducing power to the motors in a 'calm' way doesn't make a bit of sense to me. Again, there is a graphical display of the throttle setting and power setting that shows a very small delay in throttle reponse or dampening. We had a computer hardware issue a month or so ago (simple fix). The issue resulted in the tunnel shutting down with people flying several times. Not a software controlled shutdown either. Complete and immediate shutdown, the same as a power outage would be. It was a non-event. My last word on the subject: If you are flying in SVCO and the power fails, unless you are hanging off the turn vanes, you will be fine, settling to the net and looking at the controller, trying to ask why he/she cut the wind on you. And if you are on the turn vanes (45-feet up), you'll more than likely be fine also. How do I know this?, I have seen it happen. I am not speculating on how a tunnel works that I have never been to and have never flown in. I am talking from personal experience. Derek

Can you explain why it takes more than double the amount of time for the wind to reach 30 mph from 90% using the e-stop than it does using the throtle? Derek

I can tell........ I do not claim to know what happens in other tunnels if the power fails. I do know what happens at SVCO. Have you flown at SVCO? Have you been flying when the power failed? The nice thing is that faiures of the power or the the tunnel system at SVCO are extremely rare. Again, if I can jump in, fly to the turn vanes, come back down, and back out the door, all after the throttle has been reduced to zero, with the VFD braking system working, then a power outage will result in the airspeed slowing down even slower than when the VFD braking system is working, then power failures are a non issue at SVCO. The only reason I even posted to this thread is because I didn't want flyers at SVCO mislead into believing that their safety is at risk in th event of a power failure. I would not bet against you about what would happen at any other tunnel in a power failure, since I have neither witnessed, nor experienced one in any other tunnel. Why would you? I know exactly how many seconds it takes the airspeed to reach 30mph from topped out, taking the throttle to zero and when hitting the e-stop at SVCO. Do you? The sky is not falling. Derek

The brakes are the resistors within the VFD's. They act to to slow the motors faster. The tunnel slows down much faster when the throttle is pulled to stop than when using the e-stop. There is a small delay between pulling the throttle to stop and the VFD's taking the motors to stop, but we have the response time set to the slowest setting and the delay between the throttle hitting stop and the VFD's commanding the fans to stop is about 1 to 1.5 seconds. The only time the louver doors would be open 100% is for testing or removal of debris after maintenance. Simply not true at SVCO. I have experienced a power outage (doing backloops) and witnessed shut-downs. The wind speed slows gradually. Air has weight and momentum. The fans have weight and momentum. The air cannot simply stop. The sky is not falling. Derek

Never did get an answer. That is exactly what he did. Derek

I am not the FAA, but I would think it would be legal, yes. I think the deciding factor is someone making money on the deal. Derek

The FAA has violated pilots for flying jumpers w/o a commercial license. Jane F. Garvey (FAA) vs. Robert R. Rawlins. Docket SE-14006 August 21, 1997 The private pilot's license was suspeneded for 90 days for flying jumpers. The FAA argued that the DZ, even though it was a club, was being paid. Not all of the jumpers (tandems, students, etc) were members of the club and the club advertised like a business. Even though the pilot was an unpaid volunteer, they were not sharing expenses with the passengers. The shared-expense exception is only valid where the pilot and pasengers share a common purpose in the flight and does not apply to parachutist operations. Derek

At SVCO, I will have the controller cut the power. I can then hop in, pop up about 30 feet, come back down, stop, then back out the door. This is all after the power has been cut. Several of the Instructors will hop in after the power has been cut and back loop back out the door, run around the walls, etc. The wind will actually slow down slower if the power fails, since the braking system needs power to operate. A power falure at SVCO would be a non-event. Derek

Everr since USPA lowered the standards, yes. Derek

Not at all. My statements ware generalizations about the industry. As such, they hold true. There are exceptions to every rule though. DZO's could change things if they wanted to. They don't want to. Why? They like it the way it is. They want staff turn-over. If you run a good DZ, then this affects you too. If you charge the student more so you can afford to pay for proffessional, experienced Instructors, your competition will under-cut you. If you spend the money on safety, your margins are smaller than the DZO that doesn't. The industry doesn't reward quality. It won't change because the Instructors that realize how bad it is are in the minority. The majority of Instructors are happy as clams just to get paid. By the time they join the crowd that understands how messed up things are, they have already trained several people to replace them and the cycle continues. Derek

Sometimes the truth does hurt. I worked as a full time Instructor for a year and a half. I worked 7 days a week, 12+ hours a day. 1000 jumps/year @ $25.00/jump. You do the math. No benefits. No paid time off. No health insurance. Treated like an Independent Contractor and expected to act like an employee. Yelled at when I wouldn’t take my student though a solid cloud layer at 4,000 feet. Told, “You know your choices”, when I complained that the tachometer was disconnected on the Cessna and the maintenance wasn’t getting done. Then given a 1099 at the end o the year. If DZO’s don’t want to pay for good help, then they won’t get good help. You get what you pay for. The good Instructors either quit when things don’t improve or they hang on, trying to serve their students, knowing that if they quit, their students will be left to the 300-jump AFFI that is just happy to be able to skydive for a living. You say “To me Skydiving is not about making money, it's about doing what you love” That’s great, but 5 years later when you have nothing, then money begins to matter. If having nothing but being able to skydive for a living is what you want, then good for you, but don’t expect to retain quality staff by expecting the same from them. How long do you think an engineer for Microsoft would hang around if they treated them like a full-time skydiver, even if they loved their job? “I don't know if I can do this forever, having work dumped on me, being treated like money grubbing garbage and living on other peoples charity because I can't afford a place of my own with all I put in the DZ” I felt the same way when I was skydiving full time. I looked at where I would be in 5 years and got out. I was working way to hard to not have anything to show for it. Derek

1. An experienced AFFI makes no more than a brand new AFFI 2. USPA simply lowers the standard when there isn’t enough AFFI’s. 3. DZO’s make the same amount of money regardless of the quality of the instruction, quantity over quality 4. Every student thinks their Instructor is the best. 5. By the time the student figures out that the quality on instruction they received as a student wasn’t very good, they are no longer a student and can’t do anything about it. 6. USPA is run by DZO’s 7. USPA has no real authority. 8. There will always be skydivers willing to live at a very low wage in order to be a paid skydiver Instructor. 9. Once an Instructor realizes that they are being taken advantage of, they also realize that they can quit and will be replaced by 2 new Instructors, or they can keep on teaching. What they cannot do is change anything. 10. A strike will not work since most Instructors just want to get paid to jump and don’t see a problem, yet. They won’t strike. They don’t have the cash reserves to survive not working. 11. A DZO actually makes more money with brand new Instructors than experienced ones. New Instructors can be coerced/intimidated into cutting corners, doing back-to-back AFF, taking students in marginal or less than marginal conditions, etc because they don’t know any better, trust the DZO over their own judgment, don’t have much experience, don’t want to make waves, etc. 12. DZO’s can treat full-time staff like crap because they don’t have another job for their prime source of income. They have to treat the part-time staff well since they don’t need the money and can simply quit teaching at the drop of a hat. 13. DZO’s treat full-time staff like independent contractors and expects them to act like employees. 14. The turnover in Instructors works to DZO’s advantage since people expect to be treated better, make more money, etc the longer they work for a company. New Instructors realize they are brand new and don’t expect to get the benefits and treatment due an Instructor that has been around for a long time. Why give an Instructor a raise, it is cheaper to fire them a hire a new Instructor. 15. The system is set up not to retain Instructors, it is set u to encourage turnover in Instructors and that is how DZO’s want it. Derek

A tandem on mini-risers? Looks a lot smaller than 285 sq ft to me. Photo shop? Derek

No, I posted them here on DZ.com though. I don't think I did enough of them to really come to any hard conclusions except that the PD report doesn't really aplpy to modern HP canopies. Derek

I did not find that to be the case with sevral 2-canopy out test jumps. Derek

I can't say for certain why it makes a difference, but it makes a huge difference. On some 105-way dives, no one could keep up with me. on my side of the formation. One skydiver could almost keep even, but would be about 1,000 feet below me at pull time, so I could keep going for another 1,000 feet after he had to hit the brakes and pitch. He ws about a head taller than me and weighed about the same. I could consistantly track at between 70 and 80 mph fall-rate. Most people dive in their tracks, they think they are tracking great because they are going fast, but it isn't about speed, it is about angle, not speed. Derek

I tried to take seveeral side-by-sides into downplanes. They would eitheerr come back up into a SBS or come back up facing the otheer way in SBS. Think about the riser attachment points. To get a downplane one canopy must be in front and thee other in back. One or both has to have at least one line twist. I think the only to force a downplane would be to aggresively make a toggle turn with one of the canopies, trying to force it into line twists and dive behind you. Sounds like a great way to cause an etanglement. Derek

Sure, but people complain about $85 batteries, they aren't going to pony up for an AAD that lasts 50 years. What do you think a 50-year AAD would cost? I have no idea, but sounds expensive. "Worked fine", but would you expect it to work perfectly, as an AAD must? I don't think the 4-year inspection/maintannce chack is unreasonable. When I had an AAD, I had the option of skipping the 4-year, since I could keep it in my rig and pack it up myself and no one would be the wiser. I sent it in for the check. Derek

I think that like other devices such as reserves, aircraft, etc, a other Aperiodic inspection and maintenence is a great idea. Other aad' require batteries too. As for the life span, do you have a VCR that is over 12 years old? Would you trust all the internal parts to be within the original manufactuer's specs? Electrical components wear out, just like mechanical componets. It can save your life if you need it and it needs to fire when you need it and not fire when you don't. With something that important, I would want maintenance, inspections, and a life span. Derek

FWIW, I agree with John also. Simple, easier to enforce, etc. Derek

Get well super-quick Mike. Derek