strop45

OK, I'll bite. 11 seconds separation and plane is travelling at 50ft/sec relative to balloon. First group is overhead of the balloon, second group is 11*50=550 feet away. Both groups track 300', therefore there is a 50' overlap, i.e. insufficient separation. If one of the second group has a high speed mal, they are likely to fall near some of the group one jumpers. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

OK, now I can see where my thinking was going wrong. A wind powered vehicle works on energy transfer from the air to the vehicle. With a static sail, once you reach wind speed, there are no longer any collisions taking place between the air and the sail and hence you don't get any additional energy. With the wheel driven propeller, the energy for the propeller is taken from the air by slowing the air down more than a static sail would. You can get more energy because the mass of air >> mass of vehicle. I'm still not convinced that a sail powered vehicle can exceed wind speed in the direction of the wind. The speed which can be reached is a function of 1/cos(angle) and the vehicle efficiency/drag. Racing boats going downwind tend to travel at about 30 degrees to the wind for a number of reasons - the higher boat speed can give lower drag (boat will plane), most boats are more stable and safer to sail (less likely to gybe) and it can result in tactical advantages. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Actually I gained that impression from the context in which the term 'dorkzone' generally. Usually it is to indicate that the writer is amazed at how stupid the other posters are, and is often a thinly disguised PA directed at another poster. Apologies for using an in-joke about the spelling of engineer - The joke goes something like " I didn't used to be able to spell ingineerrr, how I is one" The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

That would be vice versa. Jus' sayin'. Cheers, I'm an enginnnear not a english major :-) The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Thanks for your explanation. So this vehicle will move faster than the wind - therefore it will carry on even if the wind drops to zero? The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Exactly my point - if the boat has a higher velocity downwind than the wind then the relative wind to the sail is backwards and the sail will luff or a spinnaker would collapse. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

I recently saw a study which indicated that in general people of lower intelligence regarded themselves as being more intelligent then their peers and vice versa. Do those who use the term 'dorkzone', appreciate the irony? IMHO, skydivers in general are more intelligent and capable than a random cross section of society, but may be I'm wrong and this really is 'dorkzone'. (key theme music from twilight zone) Your thoughts? The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

That is not what my colleague and Olympic triallist in Soling class tells me. Perhaps you get your colleague to explain why most boats sailing downwind will use spinnakers (if permitted under their rules). Answer: because they are very large sails and give best speed. Problem: they require the relative wind to be behind them to work and stay inflated, i.e. the boat's downwind velocity is always less then the wind speed. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

From the power available at the wheels. So where is the energy to turn the wheels coming from? This must be the true definition of a circular argument? I understand what you are saying, I just don't agree. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Understood, but where does the energy required to change the momentum of the air come from? It comes from the air driving the vehicle downwind. If the propeller is adding 10 units of energy in the direction opposite the wind, it must be removing more than 10 units in the other direction, hence the overall result is a loss of energy driving forward? Imagine a person on a trolley being powered by someone throwing them coconuts which stop dead and fall to the ground. If they catch them and throw them back they go faster. If its a machine rather than a person, the best that can happen is that 100% of the energy is captured by the vehicle. Trying to do anything else, e.g. pushing it backwards requires you to use energy (and therefore waste some) resulting in less energy transfer to the vehicle? The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

This is a key point in understanding why a wind powered machine can't sustain travel downwind at speeds greater than the wind. Remembering that wind is simply the difference in the speed of the air mass relative to the ground, then if a wind powered machine can sustain travel faster than the wind, then by definition it can move in zero wind, i.e. with no energy source. Even when travelling at 10 times the wind speed, wind powered vehicles such as wind surfers, ice boats etc all travel at less than the wind speed in the downwind direction. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Most sailing boats/wind surfers/ice boats etc can sustain speed greater than wind speed across the wind. None that I'm aware of can sustain speed greater than wind speed directly downwind. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Looking Good

I believe that if you hit a cow or a sheep here and damage your vehicle - unless the driver can show that the farmer was negligent (i.e. knew the animal was loose on the road side or fences were not adequate) generally the driver is responsible for the value of the animal. Horses and dogs, the animal owner is responsible for damage to the the vehicle. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Watching a disk format....."how many percent are there?" The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

we could call it.........a hang glider The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Humm, firstly ask yourself why do I want to jump a camera? Do you really want footage of other people skydiving?? - there's already alot of footage on youtube... I started jumping a camera on jump 200 and have carried one for most of my jumps 200-450, but now don't bother unless I jumping with a "newbie" who I know would like footage of themselves jumping. Personally I find doing a 4 way RW jump much more distracting than having a camera on, but nevertheless it is a distraction and requires time and effort before, during and after the jump. I think that you are probably better off concentrating on improving your freefall skills and encouraging/paying others to video you than playing with a camera early on. Blue skies Wayne The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

In New Zealand, the law requires ALL skydivers to have an approved AAD. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

useful when checking penetration...(for the safety conscious) The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Kia ora Rhys When you present goods at the checkout counter and hand the money over, its implicit that you wish to buy the goods. If your intentions at the time of purchase were to return it after 90 days, then IMO, it was up to you clarify that at the time. Not saying something can be as deceptive as telling an outright falsehood - see http://en.wikipedia.org/wiki/Lie#Lying_by_omission Lets turn the scenario around. You have a near new rig/canopy/reserve/AAD for sale. I phone and express interest, but am worried about the fit of the rig and whether I will like the canopy. I don't tell you that I don't actually want to buy it, just need it for a few weeks while my rig is away getting its AAD serviced. You offer to send it to me so I can test the fit and make some jumps on it. I get your rig, put 50 jumps and some grass stains on it then send it back. Legally I'm 100% in the clear, but ethically I'm up shitcreek. Of course, you would say "Good on ya mate, that's the way to do business" yeah right. Good luck with your plans for a carbon neutral DZ. Kia ora ona Wayne The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

How many animals skydive? at least one The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Some of us hunt by stalking the animal (as opposed to waiting in a hide). This requires knowledge of the animal you are hunting, good observation skills, ability to move quietly and quickly and a little bit of luck. My first real stalk was at least as exciting as my first skydive. Frankly I'd rather video/photograph an animal in its natural envirnoment than a skydive. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Interesting to compare PD to Icarus.... Wing Loadings Class 1 - Student Canopy .5 to .75 Lbs/SqFt This wing loading will perform basically as a student canopy. You may wish to choose a canopy in this range if you are very unsure of your ability, physically injured or disabled in some way, elderly or frail or as a student canopy. A canopy in this class should not be jumped in over 15 knots. These canopies are easily affected by turbulence. Class 2 - Docile .75 to 1.00 Lbs/SqFt Still a very docile range. This would suit an advanced student canopy or a first canopy for someone preferring to err on the safe side. Again affected by higher wind conditions before most canopies would be. Class 3 - Mid Range 1.0 to1.25lbs/SqFt This mid range of canopy is a good bench mark to work from. These canopies are high enough wing loading to start having a little fun yet low enough that a reasonably competent low time jumper could handle one as a first canopy (check with your C.S.O.) and still have a canopy they want to be jumping in a couple of hundred jumps time. This is also getting into the range that must be treated with a little respect however still has a reasonably good margin for error. Most of the canopies we sell are in this range. From this loading up, most wind conditions allowable for jumping are not a problem. Class 4 - High performance 1.25 to 1.65 Lbs/SqFt Now we're having fun ! We qre also into potentially high danger area! Turn speeds are increasing air speeds and speed range are increasing dramatically all of which provides us with a direct trade off between fun and safety. Canopies in this range must be flown to the ground! Recovery arcs are generally over 200 feet and toggle input movements are getting noticeably shorter. A high degree of experience and competence is necessary to handle a canopy in this range. Flying a canopy in this range must be done by feel, every maneuver must be well planned ahead as things are happening very quickly. With a high wing loading turbulence will affect the canopy less but if affected remember you are traveling much faster. Being dropped 1/2 a meter by turbulence under a class 2 canopy is not even going to affect your stand up landing but being dropped 1/2 a meter in the middle of your ballistic turf surf could ruin your summer. The same goes for other obstacles - buildings, fences, people, other canopies, etc, have much more impact at high speeds. Even uneven ground or short landing areas should be considered obstacles. These canopies will still be traveling horizontally in nil wind conditions. A collapsible pilot chute is recommended. Lowering the slider and loosening the chest strap is suggested. Class 5 - Extreme 1.65 to 2.00 Lbs/SqFt Not for the faint hearted. If you are one of the few people that want to fly a class 5 canopy consider every aspect of what you are doing very carefully. On the up side there is very exhilarating airspeed, quick response times and powerful maneuverability. On the down side our margin for error has reduced to almost nothing (!), compounded by the fact that if we do make an error we are almost certainly traveling at speeds that can maim. If you have or are considering a class 5 canopy we can't tell you how to fly it in this overview, we must assume you know what you are doing. Most people I watch flying class 5 canopies don't fly them to the limits of the canopy and the performance they achieve from their canopy could be achieved from a class 4 canopy flown to its limits with a far greater safety margin. These canopies generally have to be run out on landing. They must be fitted with a collapsible pilot chute. Lowering and collapsing the slider and loosening the chest strap is recommended. Canopy recovery arcs can be over 400 Ft radius. The step from a class 4 canopy to a class 5 canopy can be quite large i.e. for a 80 kg jumper with gear and weights the difference between a 105 and a 95 feels similar to the difference between a 130 and a 105. Class 6 - BALLISTIC 2.0 to 2.4 Lbs/SqFt If you are considering this, you don't need an explanation. The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

The only part of this post I can agree with is the last sentence. Everything in life carries risk, everything in skydiving carries risk... The difference between stupidity and genius is that genius has its limits." -- Albert Einstein

Since you have don't have 1000 jumps and post such nice things, I guess you are a really great guy who is always keen to listen and learn The difference between stupidity and genius is that genius has its limits." -- Albert Einstein