alan

Partly because it is amusing and partly because there seems to be an abundance of very knowledgeable people who don't seem to be able to grasp frame of reference. It is the ground. I stated that very clearly in my first reply to you. That by the way, is what has made this amusing. Semantics? Naw, if it was just that I wouldn't care. alan

The ground (a good frame of reference for skydiving purposes) always seems to be there, the observer on my back.......very seldom, and to date, never as my d-bag decelerates away, although I've had a few tandem passengers on my front. REALLY. As I stated previously, you, the pc, the d-bag, the harness/container, and even the observer are all travelling towards the Earth (same thing as the ground for our purposes) at about 176 feet per second. After you let go of the pc, it is no longer travelling at Earth at 176 feet per second, but at increasingly slower rates over time. You on the other hand continue at 176 feet per second for a brief period of time, until the drag of the pc pulls the pin, decelerates the d-bag and the canopy (aerodynamic decelerator) goes through the opening sequence and ultimately decelerates you (and your observer if he/she is still attached) to something around 15 feet per second, which is what the pc and d-bag are now doing. Hey Bill, you're out in Poynter country, heck you've probably even met the man. Perhaps you could find out why he did't call the book something about aerodynamic accelerators or aerodynamic negative accelerators. alan

Please accept my apology, I refered to an apparently obsolete 1992 Webster's Dictionary of the English Language, which I thought would be close enough to "as most people" would use the word. It defines it as negative acceleration. Referencing acceleration with repect to Physics it says; The rate at which the velocity of a body increases per unit of time: used also of decrease of velocity, which is expressed as a negative acceleration. Going in circles but it seems as if acceleration involves an increase in velocity and deceleration (negative acceleration) involves a decrease of velocity. Can you please explain why Poynter would have been so misguided as to title his book, THE PARACHUTE MANUAL A Technical Treatise on Aerodynamic Decelerators? See, here is where the world of Physics seems to have some contrast with the real world. We'll both drive at a wall at say 20 mph. As well approach the wall, I'll decelerate 15 mph so I impact the wall at 5 mph. You on the other hand, can accelerate the same 15 mph and impact the wall at 35 mph. Or, better yet, I'll accelerate away from it from 60 mph to 120 mph, while you decelerate into it. You'll soon discover the difference. alan

Again, bad schooling/learning on my part. We were taught that in velocity^2, that the 2 was called an exponent. Hence I derived the increases exponentially. By the way, what is the 2 in this case called? No arguement. But that would mean that aceleration is not the same as deceleration......."negative" aceleration is. OK. I'll get in a car and acelerate from 60 mph to 120 mph away from a brick wall. You get in a car and decelerate from 120 mph to 60 mph towards the brick wall. Or try this one, I'll travel towards it to. We both start at 20mph. I'll decelerate 15 mph and you acelerate 15 mph. Funny, out of all my comments people choose to reply to, none has addressed why Poynter titled his book THE PARACHUTE MANUAL A Technical Treatise on Areodynamic Decelerators. Why didn't he call them Areodynamic Acelerators? alan

I charge $30, includes inspection and packing of the main as well. alan

I must have been exposed to some faulty science books. E=mc2 is what we learned. But if you say Momentum is mass times velocity, I'll take your word for it with a degree of scepticism. alan

Please accept my apology for the untimely nature of my reply, I've been away for several days. Yes, I believe my exact words were, "Energy is equal to the mass times the velocity squared, ". What is unclear about that? Once again, I think I said the same thing. Here is what I said, "The value of energy changes exponentially as the velocity changes and in one case energy is increasing and in the other it is decreasing." Maybe I didn't put enough emphasis on the word change for you. OK, if you say so. But, if you are in a car travelling at a brick wall at 10 mph, would you rather be accelerating or decelerating? I think I understand though, you would not mind acelerating as long as it had a negative value. I think most of us laymen understand the difference between accelerating towards a wall and decelerating towards it. Our world consists of a reality that extends beyond numbers and formulas. I am a layman. I would venture to guess that half or more of the people reading this forum are laymen. I think it was appropriate to use the term in view of the context. Once again......"I'm trying to think of a reason why Poynter refers to his Parachute Manual as " A Technical Treatise on Aerodynamic Decelerators" instead of Accelerators. " alan

Sorry for the late reply, I've been away for a few days. I stated that energy is equal to mass times velocity. How is that wrong? I don't think so. I'm thinking of the pc and freebag relative to the ground. So then there really is no such thing as a hard opening? alan

Energy is equal to the mass times the velocity squared, I think I understand that part of physics. The value of energy changes exponentially as the velocity changes and in one case energy is increasing and in the other it is decreasing. I'm trying to think of a reason why Poynter refers to his Parachute Manual as " A Technical Treatise on Aerodynamic Decelerators" instead of Accelerators. I mean, hey, as far as pysics is concerned, it is the same thing, right. Einstein not withstanding and for all reasonable purposes, gravity is a part of the environment we live in, as is the earth. As far as an illusion, how many times have we heard a whuffo ask "why are they going up so fast" after viewing a video of a tandem opening as the videographer falls away? We know they are not going up. They are still going down. They are decelerating. The resultant energy is being reduced. It only appears as if the tandem pair is accelerating away from the camera because the camera is still travelling at a relatively constant velocity at that point in time. alan

Exactly wrong. Perceptions and illusions have always been a good substitute for reality. alan

No, the bag is decelerated relative to the jumper. You'd be incorrect in your matter of taste. But then, it is only skydiving, why be precise and accurate when "well, we all know what you mean" will suffice. alan

I thought it was deceleration. You, the container, bag, etc. all falling at something around 176 ft/sec under reasonably normal circumstances. The pc is deployed and generates drag that is transmitted to the bag via the bridle. The bag pulls away from the pack tray because it falling slower than the rig and jumper. The locking stows are to keep the canopy in the bag until lines stretch. If, as you point out, the bag is stripped off the canopy before line stretch, the abrupt and unstaged deceleration can cause serious injury or death to the jumper and damage the equipment. alan

Yes, I've read that. I just thought some discussion and explanations here by Mr. Booth would be beneficial and reach more people. Maybe I was wrong and should just assume everyone will get all of the information they need from the RWS web-page and manuals. It does provide a nice start though. alan

Bill, you provide a considerable amount of expert and valuable information here. Can you discuss the two? Should the Collin's Lanyard be standard on RSL equipped rigs? What about the Skyhook AND a Collin's Lanyard? Any and all thoughts would be welcome. There have to be a few people out there thinking "Collin's Lanyard, what's that?". alan

You're right, years ago Jumpshack included the disconnect rule in their owner's manual because of the cross-connected RSL. Dig around here in Dropzone.com, I'll bet you can even find a discussion on it by John Sherman. The rule seems to have stuck around though, even since Jumpshack dealt with the problem, mostly I believe because of the dual square out studies that have been done. The cross-connected RSL had its' merits by the way. It was intended to ensure that when BOTH risers were released, the reserve would deploy. Jumpshacks design was less than optimal. The Collin's Lanyard currently seems to be the best option for ensuring that when the RSL deploys the reserve, both risers are cutaway. Odd that it is not standard on all RSL equipped rigs. That brings to mind a question for Bill Booth........... alan

There is not a high probability of this happening, but it can happen. There is a dual square out report available on-line that details how a riser from a cutaway main can snag on the reserve, so it would seem that an additional piece of webbing flopping around would increase the probability. I think the report is somewhere here in Dropzone.com and maybe in PD's website. I can't recall any fatalities in the last 12 or 13 years as a direct result of the RSL snagging the reserve, but then my memory is not perfect. You could search the fatality reports. Keep in mind that it would not always result in a fatality. Although the circumstances were not exactly the same as what you are asking, I can recall Mike McGowan having a riser from a cutaway main snag on his reserve slider and drag the slider up and choke off the reserve. He crashed into some trees and survived. Good plan.....if you have time and presence of mind, do it, it can't make the situation worse. 700 feet? You may still have plenty of time, but that would depend on you and how well you could assess the situation and respond. Just curious, you are in a downplane at 700 feet, just exactly how are you going to steer yourself to the landing spot? Once you are there, assuming you find a way to do that, do you intend to land the downplane? I know what you are asking though, disconnect the RSL then chop or just chop. You have to chop, even if time and altitude do not allow you to disconnect the RSL. What is the limit? Depends on how cool you are under pressure. You asked the right questions. alan

On some rigs it is and on some it is not. alan

Thanks for the information Bill. I've been watching the fatality reports in Parachutist for 12 or 13 years now. Have I missed something? Are there any documented incidents of the top flap design on a reserve container causing it to total mal in field use? alan

Actually, the point of the pissing contest is to get the point across to you that you did NOT present VALID reasons. You bought into an old myth. Kinda like the old "you have to hook it to get decent landings". alan

Yes and don't forget they also have to pull the freebag past an additional 1 and 2 flaps, respectively. alan

Sunpath also followed the leader in adopting ringed harnesses, RI patented that. Oh, and while we're at it, they and others, follwed RI in using hard riser inserts for the cable ends. alan

Thanks all......I think I have a viable plan from what you have shared with me. alan

Sorry if this a little off the beaten path for Gear and Rigging but I need to know of some options for spreading ashes in freefall and don't want to reinvent the wheel if I don't have to. I'm looking for something tasteful, reliable and safe.......really cool would be OK too. We are near a populated area so we really don't want to drop anything other than harmless ashes. A bag with a ripcord and handles, that can be tucked into a jumpsuit after it has done its' job?? alan

I put a caribiner on the top grommet of the flag and snap a loop of bungee cord that has a foot loop on it onto the bottom grommet. Pack it into a fanny pack that hangs off my belly with the biner and loop on the top. After opening, I take the biner in one hand and the loop in the other, carefully letting the flag trail behind me in the process. Snap the top biner into the rapide link, the lines or even a dive loop and place the bungeed foot loop over your toes. Just prior to landing, you can kick the foot loop off and the flag will trail behind you, off the ground. Works well with flags that are not over 6' tall. alan

It would be nice if the conversations were at least related to something about parachutes/gear/rigging. Try pm for this bullshit. alan