michaelmullins

West Tennessee Skydiving, near Memphis, TN, will take you Tandem or AFF at age 16 and do it in full compliance with all USPA rules and regulations. See: http://www.SkydiveKingAir.com

Sorry to be so late getting into this thread. It's been a busy night at the radar scopes. It's not that the forces "cancel each other", They are quite independent. When you jump out of a plane, you immediately start to slow down along your horizontal path because of wind resistance, correct? This decelleration causes your body, including your inner ear, to undergo a positive G, not towards the Earth, but towards the forward horizon. For the first few moments out the door, "straight down" is towards the front of the plane, not just from a relative wind point of view, but from your gravity vector as well. As you continue to bleed off your forward speed and pick up your vertical speed, your gravity vector moves down towards the planet. It's not the lack of gravity, but the moving about of the vector that can be disorienting on exit. If you exit at an airspeed equal to your terminal velocity, you feel exactly 1 G of wind force accelerating you backwards. Faster or slower exit speeds give you more or less G load. Zero airspeed, such as a balloon or hovering helicopter, give you zero G loading, therefore making your stomach "feel funny." Indeed I had stated in my previous post that: "Horizontal acceleration/deceleration and vertical acceleration/deceleration are totally independent events and one does not affect the other". However, it is a fact that the net result of the G of the two forces can cancel one another as far as the sensation your body feels (or make the sensation more positive or more zero G). If you push a an aircraft over in flight you can get zero or negative G. If you bank the aircraft while pushing you can get the positive G of the bank to negate the less than 1 G of the push and what you feel is 1G and this is a common technique in high performance aircraft to avoid zero or negative G when you need to level off quickly. What I said is the slower the airspeed of the exit the less positive G you feel (that "droopy" feeling when you are subjected to less than 1G) which is the same as you have stated. At faster airspeeds you will feel over 1 G. Mike

I have explained the sensation in an earlier post in this thread but here it is again: Here is the correct answer: When a skydiver leaves the aircraft in horizontal flight he has the full horizontal speed of the aircraft at the instance of exit. The skydiver will then decelerate horizontally while accelerating vertically. Horizontal acceleration/deceleration and vertical acceleration/deceleration are totally independent events and one does not affect the other. For example, if you place a rifle horizontally to the earth (assuming for this discussion that the earth is perfectly flat) and fire the rifle while simultaneously dropping a bullet the same distance that the rifle is above the ground, both bullets will hit the ground at the same exact time. Vertical velocity due to the pull of gravity is always independent of horizontal velocity. When a skydiver leaves an aircraft with horizontal velocity he decelerates horizontally while accelerating vertically. These forces of acceleration and deceleration cancel one another and your body does not feel the "zero G" sensation. The slower the aircraft exit speed, the more likely you are to feel the vertical acceleration. In a balloon or hovering helicopter with zero horizontal airspeed you will feel the full vertical acceleration. In summary, the slower the aircraft exit airspeed the more likely you are to feel the zero G sensation. Mike Mullins

As a jump pilot, when the last of the jumpers are out the door, and you push the yoke to dive towards the ground, do you get the "droppy" feeling from the lessened G forces when you start your dive and accelerate vertically? Any pilot who pushes the yoke forward will experience a less than positive g, depending on how fast and far you push the yoke forward. However, you can always cancel less than positive g with positive g. A roll into a steep bank will pull more than level fight positive g and it will cancel out the push forward and the net effect can be 1 G, or whatever you wish depending on the manipulation of the controls. Mike

It is a dirty, rotten, thankless job but someone has to do it, grasshoppa. Mike

Not quite. Aerodynamic drag doesn't care which direction the wind is coming from, it only cares about the magnitude of it, squared. This mixes up the two components of acceleration so the horizontal component of drag will affect the vertical acceleration due to gravity and this produces a slight amount of lift. Take two identical jumpers, one in a balloon and one in a plane, exiting at the same time. The jumper from the balloon will find themselves at pull time a couple of seconds sooner than the one from the plane due to this effect. It's a well know physical phenomenon. Granted. However, the purpose of this discussion was the analysis of the sensation the jumper experiences. The aerodynamics you discuss, while correct, do not alter the sensation and explanation of same. Mike

Is that realy correct? I think a lot of skydivers say they don't experience the droppy feeling because they have just gotten used to it over time, and it doesn't take very long. But initially, I think novice jumpers DO feel it for the first several jumps. And I don't think it has anything to do with the horizontal speed of the aircraft or the wind when you exit. It's entirely a function of VERTICAL acceleration only. If you were moving horizontally at 120 mph on a roller coaster and suddenly hit a steep drop, I think you ARE going to feel the droppy feeling, simply because of the vertical drop alone. Likewise, if you jumped from a jet fighter flying horizontally at 600 mph, you would still feel the droppy feeling as you accelerated downward vertically, despite your high horizontal speed. The droppy feeling comes from negative G-forces, i.e. being lighter than the pull of gravity. G-forces are defined as x, y and z, where x is the forward direction, -x is backwards, y is to the left, -y is to the right, z is upward, and -z is downward. Or something like that. Positive z forces produce the "heavy" feeling as your weight is increased by more than normal acceleration. Negative z forces produce the "droppy" feeling as your weight is decreased by less than normal acceleration. That's the way I see it. I think I agree that it IS about acceleration, but disagree that the DIRECTION of acceleration is irrelevant. And there is probably some human physiology involved too... So, which view is correct? Here is the correct answer: When a skydiver leaves the aircraft in horizontal flight he has the full horizontal speed of the aircraft at the instance of exit. The skydiver will then decelerate horizontally while accelerating vertically. Horizontal acceleration/deceleration and vertical acceleration/deceleration are totally independent events and one does not affect the other. For example, if you place a rifle horizontally to the earth (assuming for this discussion that the earth is perfectly flat) and fire the rifle while simultaneously dropping a bullet the same distance that the rifle is above the ground, both bullets will hit the ground at the same exact time. Vertical velocity due to the pull of gravity is always independent of horizontal velocity. When a skydiver leaves an aircraft with horizontal velocity he decelerates horizontally while accelerating vertically. These forces of acceleration and deceleration cancel one another and your body does not feel the "zero G" sensation. The slower the aircraft exit speed, the more likely you are to feel the vertical acceleration. In a balloon or hovering helicopter with zero horizontal airspeed you will feel the full vertical acceleration. In summary, the slower the aircraft exit speed the more likely you are to feel the zero G sensation. Mike Mullins

The droppy feeling comes from negative G-forces, i.e. being lighter than the pull of gravity. Skydivers cannot experience negative g from freefall acceleration only. They can only feel a maximum of 0 G. Further, when skydivers say the felt "negative G" in an aircraft, I doubt it. If they felt negative 1 G then they would have hit the ceiling of the aircraft with their head with their full body weight, likely resulting in injury or death. I employ a technique just before exit where I put the aircraft in a little less than 0 G, say .1 G, which allows tandems and military jumpers with 100 lb rucks to stand up as their body weight is now only about 20 to 30 lbs but this is still positive G, not negative G.

. Oh well, I'm a maroon.

West Tennessee Skydiving, 35 miles east of Memphis, we are very cool. http://www.SkydiveKingAir.com Mike Mullins

IIRC USPA okay-ed Pink Bull to do it on 'demos' for a while...the Bull wanted a permanent waiver for their guys only. I don't think that went as planned. I would imagine a special waiver would be available for a commercial film stunt...whether they had one is another question. I do not recall USPA granting any waiver to Red Bull to use base rigs on jumps from aircraft and I doubt that it has ever happened. Mike Mullins USPA National Director Yup, Sorry Mike, I see that it only passed committee,...I'd been told they had waivers for the jumps they did do. Taken from the board meeting minutes ~ 7. Two-thousand-foot deployment limit for demo jumps—the Red Bull team has requested a waiver to deploy at 400 feet on demo jumps using specialized equipment. Special Instructions from the FAA attached to each approved 7711 authorization require all jumpers to deploy at 2,000 feet or higher. This was discussed at length. This motion passed Committee 4-3. Ed Scott presented input from the FAA on these types of jumps. The following motion was presented: Motion 33: Failed, 4/17/0 (Mr. Spillers) “Move to waive BSR, 2,000’ opening altitude, for Red Bull team members named below. This waiver applies to jumps where an air show line is in place and TSO rigs will be used. Opening altitude shall not be lower than 800 feet. To include up to 5 practice jumps at a consenting DZ. Jumpers include: Charles Bryan, Miles Daisher, and Mike Swanson. Waiver shall expire in 120 days.” ~ I always wondered who the 4 were that voted yes, and what their affiliation with Red Bull is/was? The request from Red Bull was for opening altitude only, not for the use of base rigs, thus my original post. Just wanted to clarify. Mike Mullins

IIRC USPA okay-ed Pink Bull to do it on 'demos' for a while...the Bull wanted a permanent waiver for their guys only. I don't think that went as planned. I would imagine a special waiver would be available for a commercial film stunt...whether they had one is another question. I do not recall USPA granting any waiver to Red Bull to use base rigs on jumps from aircraft and I doubt that it has ever happened. Mike Mullins USPA National Director

As a USPA Member you are only required to comply with the Basic Safety Requirements (BSRs) which are Section 2 of the SIM. EVERYTHING else in the SIM are recommendations and the two examples you provide are only recommendations. BTW, contrary to common belief, there are no currency requirements in the BSRs. Mike Mullins USPA National Director

Same size.

Which tandem manufacturer's gear are these jumps being done with? Eclipse? Basik

Sorry, but the above statement is completely wrong. USPA will allow Tandem Jumps at 16, just as they allow solo jumps at 16. There is a BSR that a USPA Tandem Instructor must comply with the age requirements of the tandem system manufacturer of the tandem system they are using. There are tandem manufacturers that set no age limit and a USPA Tandem Instructor is perfectly legal taking a 16 year old on such a system. Mike Mullins USPA National Director Member, Safety and Training Committee Thank you for the clarification, it appears my information was out of date and I should have checked the resources available. It's also a great example of the USPA BOD not following through on a commitment. Do not know of what commitment you speak. There are 22 voting directors on the board and they may all have different views on different subjects. After presentations by an attorney speaking for the tandem manufacturers the BOD voted to grant the request of those manufacturers by requiring all USPA Tandem Instructors to comply with the age requirements specified by the given manufacturer. Mike Mullins USPA National Director

West Tennessee Skydiving will take tandems at 16 or 17 provided one parent is present and the other parent is either present or sends written permission. These jumps are USPA and FAA legal in all aspects. Mike Mullins

Sorry, but the above statement is completely wrong. USPA will allow Tandem Jumps at 16, just as they allow solo jumps at 16. There is a BSR that a USPA Tandem Instructor must comply with the age requirements of the tandem system manufacturer of the tandem system they are using. There are tandem manufacturers that set no age limit and a USPA Tandem Instructor is perfectly legal taking a 16 year old on such a system. Mike Mullins USPA National Director Member, Safety and Training Committee

1 fat skydiver, 2 skinny ones.

West Tennessee Skydiving now owns a Hiller UH-12C Helicopter. It will be available for hovering jumps at the boogie, $50 to 3,500'. Unlike everything else at WTS, it is not particularly fast. Mike Mullins

We are going to toss a deaf guy but did not want to advertise it. Damn... Got me good. It's easy to toss them, they can't hear you sneaking up.

October 28-29-30 See: http://www.skydivekingair.com/halloween/

Just go to the top of the thread and reply to him. Mike

Since you replied to me I want it to be perfectly clear that I was not the one accusing anyone of wrongdoing, I was pointing out to the one originally pointing the finger that this jump could have been made completely legal under all standards (USPA & FAA). Mike Mullins