sundevil777

Kapow had a VERY cool feel to it. I enjoyed almost 8 years of many of my best jumping there. The view in Shelton I'm sure is great in its own right. Wasn't there another DZ at Shelton? Does this mean they have merged, or did their operations stop? Velocity moved away from the DZ a while back, but now is much farther away. 50 cents per jump seems like a lot to me. edit - I think we should start posting pics from Kapow in this thread, both ground and aerial. I'm sorry to say I don't have any digital pics, and my scanner is not cooperating. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Both, but as you suspect, mostly the latter. As much as I don't like taking orders from you , I will now let it go. I won't care anymore about how much anyone loves Kallend's terribly flawed analogy. That will be all from me on this - probably will make a lot of people happy. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

No, that is not the problem statement. Pilotdave posted the link to the physics forum. The problem statement there is much clearer than how it was mis-described at the beginning of this thread by BoostedXT. http://forum.physorg.com/index.php?showtopic=2417&st=0 It is the speed of the 'plane', not the wheels/rotating point on the wheels or anything that might be confusing about using some point on the wheels. Also, there is nothing to keep us from defining the speed of the conveyor and plane as relative to the ground. It would have been nice for this to be stipulated in the problem statement, but maybe it would be less fun for those that design such mind teasers, because people would get it quicker, and not be tempted to think the plane can't move, can't get airspeed. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Yes, the plane can move. The conveyor belt is not intended to keep the plane stationary relative the the ground. Only to move the opposite direction of the plane, at the same speed as the plane, both speeds measured relative to the ground. The wheels of the plane will go twice the speed of the plane (speed of plane plus speed of conveyor), so there will be a little bit of extra friction for the plane to overcome. Maybe the only thing this 'riddle' shows is that people naturally want to come to the conclusion that the plane can't move forward. The speed of the conveyor and speed of the plane can be identical and in opposite directions, and still have the plane moving relative to the ground because the wheels roll. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Your standard for a good analogy are pretty low. Kallend's analogy, actually it is not an analogy, just a question: He doesn't even explain why they go farther. He does throw in the term ballistic coefficient without defining it. Even went so far as to say: That is false. He later quoted the official weight of a dart and birdie, but then why say, "regardless of mass"? If you think I'm nitpicking, so be it, you've said it. You don't have to keep replying. He also said that regardless of mass all that matters is the BC. Of course this is true, but is a whole lot less useful than explaning that mass and drag are the only variables that define BC. FAR from perfect. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

I agree, there is no analogy needed, especially one that varies both drag and mass. And I also agree that I don't expect anyone to think freeflyers weigh more, but Kallend kept asserting that I and others must think that all skydivers weigh the same, so I offered a bad conclusion from his analogy. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Thank you for agreeing with me. It doesn't mean that we consider all jumpers to weigh the same, just that for purposes of anologies, only having the drag vary is most useful for the 'physics challenged'. To introduce the effect of weight is best left to a separate analogy, instead of mixing both variables at the same time, in my opinion. Kallend, to throw out the term ballistic coefficient, without even defining it (I did that), doesn't enhance understanding of the exit trajectory question. Your birdie & dart analogy is FAR from perfect, it sucks, because both of the important variables changed. It is like implying that freeflyers present less drag on exit, and also weigh more. Not everyone will see that implication, but it is there, and your advocacy of this analogy (against my "nitpicking") does the 'physics challenged' no favor. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

I believe that many religious leaders would make it much harder to get divorced. I would support that also. Just denying the existence of the war on Christmas doesn't make it so. You'd like that to be enough, but it isn't. Sam Donaldson of ABC news used the term 'a bunch of yahoos' to describe those that believed in the war on Christmas. If that isn't a perfect example of the liberal media's arrogant elitism, I don't know what is. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Please understand that the original problem statement in this thread is misleading. I'm making this conclusion from the link PilotDave provided (see post 37): http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2006441#2006441 It is the speed of the plane (body of the plane) that will be matched by the conveyor. The speed of the plane and speed of the conveyor should be considered to be the speed relative to the ground. This means that when the plane is going 10mph forward, the conveyor will be going 10mph backward, so the wheels will be spinning at 20mph. This will have the effect of some extra friction from the wheels, and that is all. It does NOT meant that the conveyor is defined so that it moves in a way to keep the plane still relative to the ground. We all know that air moving over the wings is what makes lift. Please realize this fundamental difference. The plane will take off with a little extra conveyor/runway length required. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

I like the alternative that freeflajankie and I have, it only sticks out from the pocket a little, but is the normal length/fits into a std D-handle pocket. Not only do I like it for being somewhat less likely to be snagged, but the std D-handle was giving me bruises. This is of course partly due to me being 'thicker' than I should be. edit to add - I found my low profile handle to be extremely easy to use.

FFers like to exit with their head into the wind. RWs like their chest into the wind. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Sure it does, and here's the problem: 1 - can't generate lift without forward airspeed 2 - can't generate forward airspeed without forward groundspeed (because there's no wind) 3 - can't generate forward groundspeed without the wheels rolling (because you're resting the entire weight of the plane on the ground) 4 - if wheels roll, belt fights back 5 - can't beat the belt unless you beat friction 6 - can't beat friction unless you generate lift 7 - see 1 As they say, "You can't get there from here." Physical experiments aren't going to demonstrate this properly because a belt that can instantaniously match the speed of a wheel rolling along it is a non-causal system, and is not physically realizable. Any lag whatsoever in the feedback loop between the sensor that's measuring wheel speed and the motor control that's driving the conveyor will allow the plane to take off. But that's not what the original question is asking. The conveyor matches the speed of the plane, relative to the ground. The conveyor moving doesn't mean the plane stands still relative to the ground, just the wheels would spin faster than normal, with a little extra friction for the plane to overcome. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

One of the posts from the physics forum sums up the incorrect assumption that so many make: This is of course wrong! The original problem states that the converyor speed will match the speed of the plane, NOT that the conveyor will move at whatever speed is needed to keep the plane still. The wheels will just be rotating extra fast with some extra 'drag' force that the plane will need to overcome. It is amazing how so many did not understand the original problem statement. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

That link says that the conveyor tracks the 'plane speed' (as opposed to the wheel speed) and makes the conveyor speed the opposite. This is an easier to understand scenario. The video of their experiment is pretty funny, but not exactly going to convince those that think don't agree with the conclusion. Some of the posts on that site also incorrectly state the scenario to require that the conveyor move such that it forces the plane to remain still. This is not the case, the conveyor is just supposed to move backwards at the same speed at the plane moves relative to the ground. A skateboard is not such a good example because there is very little deflection of the 'tires' from the weight of the skateboard, so the rolling friction is very low. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Use a sturdy box, with the rig in a couple of garbage bags, and wrap the box with packing tape all the way around in both directions in several places. Pack it like you know that it will be repeatedly tossed around and landing on concrete floors, and being crushed by many other heavy boxes. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

The conveyor would match the speed of the rotating wheel, but that would not be the speed of the body of the plane. As I described in my earlier post (#24), even if the conveyor started accelerating before the engine started to provide thrust (I think this is a useful hypothetical), the body of the plane would not be moving as fast as the conveyor, because the wheels would start to spin. If you extend this conclusion, with the engine providing thrust, then the conveyor would provide a rearward push to a small degree, that depends on the rolling friction and rotational inertia of the wheels. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Answer is the BC only. So what, the issue is why do people go farther forward in the direction of travel when they exit head down (head into relative wind). The important thing changing is the drag, not mass. You put forth an analogy that added in a different mass, which was not relevant to a person knowing why their own trajectory will be different depending on how they exit. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

He didn't say it would match the speed of the plane, it would match the speed of the rotating wheels. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Sounds like the engine didn't quit completely, so maybe the pilot was still getting and counting on some power during the approach. Would have been better to treat it as a dead stick and just idle the engine, let it stall and leave it alone. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

The plane cant go anywhere without its motors. The plane gets its drive from its engines not the wheels spinning. Think about a person on a treadmill with rollerskates on holding onto a rope. The treadmill could be going 60mph against them, but if they were holding on to the rope they could still move forward against the treadmill by pulling with their arms. The planes wheels like rollerskate wheels are there to roll NOT propell. I understand everything you stated. It is your scenario that is hard for everyone to understand. I was just proposing a scenario that shows that in an idealized case with perfect wheels/tires (friction between conveyor and tire, but no wheel bearing or rolling friction from tire deformation and no rotational inertia), the conveyor can't move the plane at all, because the wheels would just spin (there is no friction or rotational inertia of the wheels/bearings). As you go away from this idealized case, the movement of the conveyor would make it harder to achieve increasing airspeed. As others have said, if the conveyor keeps trying to match an ever increasing wheel speed, in part due to the conveyor itself, then it would quickly spin up to an infinite speed, theoretically. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

I think his scenario is that the conveyor goes the opposite direction. I propose that we think of it this way. If you have perfect/idealized wheels/bearings with no friction or rotational inertia, then a plane with the engine off would not move (the wheels would just rotate) as the conveyor accelerated in either direction. Since the wheels are not perfect, they would not start rotating as fast, and would cause the plane to be moved at some rate less than the speed of the belt, so it would be slightly harder for the plane to get up airspeed. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Yes, it would take off. But, your scenario is a little weird, if it were to try to match the speed at any time, then it would actually try to keep the initial state, a zero rotational speed of the wheels. That assumes it can respond instantaneously. Even if it were opposite, to rotate the wheels faster, unless there is a lot of friction from the wheel bearings, it doesn't matter. The motive force is not from the wheels. The only thing holding the plane back that has to do with the wheels is the rolling friction from the tires and the wheel bearing friction. Those effects are likely to be slight. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

The birdie and dart analogy is lousy because both the weight and Cd are very different - very different. I realize you won't find a birdie that is heavier than a dart, but there is nothing special about that analogy, and because it includes the 2 variables that define the BC as changing, it is less instructive than an analogy where only 1 variable changes. So the effectiveness of the analogy is lost when someone asks, "Is it the mass or drag that causes the change?" The answer to the question is yes, both. Why not just use an analogy where the drag changes, with mass constant. Same jumper, exiting in a different orientation. Why is a lesson on ballistic coefficient needed? The important variable being changed is drag, not mass. The mass of jumpers is not constant, but is less of a variable than the drag from exiting in different orientations. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Just ask them to tell you which of Newton's laws they used to justify it. A condescending reply such as that will do nothing to get them to see the light. They will be less likely to want to listen to you when you do explain the principles in a way they can understand. So you're smarter than most jumpers when it comes to physics, but the DZ is not your classroom, other jumpers are not your students. People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

Add weight to the badminton birdie so it weighs about the same as the dart. The dart will still travel farther horizontally in the given scenario. Doesn't matter. Not all skydivers are the same weight, are they? Wrong, it does matter, in that if the birdie is heavy enough, or the dart light enough, the birdie will go farther than the dart. Are you this stubborn with your students? People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am