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Large Formations

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[ Intro ] [ Equipment ] [ Dive Plan ] [ Aircraft ] [ Setup ] [ Docking ] [ Catching ] [ Flying in Formation ] [ Break off ] [ Landings ] [ Emergencies ]

Introduction

    To increase the likelihood of successfully and safely designing and building large formations, you should use compatible equipment, design aerodynamically stable formations, use skilled & competent parachutists, and build up the skill & experience level of the participants over a number of increasingly larger & more complex jumps. It is only when we deviate from the above factors that we encounter problems. Hence, big way CRW can be safe if done correctly, but if we deviate from the fundamental principles, they can turn nasty very quickly.


Compatibility and Equipment

    For the sake of aerodynamic & organisational simplicity, a perfect formation will contain a group of parachutists with exactly the same flying characteristics. This implies the same descent rate, the same forward speed, the same wing loading, no grip tension, and the same canopy airfoil. Following is a list of each characteristic that would contribute to this ideal situation. Aim to have matching characteristics with each member of a formation.

Canopy / Airfoil Design: Use the same type of canopy throughout the formation. This means matching the manufacturer, model, options (ZP versus F111), line type (thickness), and degree of wear and tear.

Wing Loading: this is where we consider canopy size. It is easiest to match the canopy size and then adjust wing loadings by adjusting weights. Higher wing loadings lead to greater sensitivity in control inputs. Although you want good control over your canopy, you don't want it to be too twitchy as the slightest harness adjustment or perturbation in the formation may lead to trouble. However, you do need a certain amount of pressurisation for the canopy to be controllable and fly efficiently. You don't want an underloaded canopy as you will have a higher likelihood of wraps and depressurisations when the formation is subjected to a bad dock or turbulence. You need to find a balance. A wing loading in the low to mid ones is considered appropriate by most big formation experts. The aim wing loading for the 2003 World Record Big Ways was 1.3 lbs/ft2.

Lines & Line Trim: many manufacturers have different trims designed for different disciplines in CRW. In particular, many manufacturers have sequential and rotations trims. The trims will affect descent rates and forward speeds. There is also the issue of line retraction due to wear and tear and age as well as damage, repairs, and replacements.

    Measure and compare the line lengths and trims within an individual canopy - measure the outer A line on the left side of the canopy and compare it to the measurement of the outer A line on the right side of the canopy. They should be the same. Do this for each pair (centre A, brakes, outer C, etc).

    Do this for all canopies in a formation and compare the line lengths and trims between canopies. If there are vast differences in the lengths then you may encounter problems in the formation. For example, if one canopy has 9 foot lines trimmed at a high angle of attack, and another has 7 foot lines with a flat trim, they are going to struggle to fly together.

Brake Settings & Toggle Length: you should have already measured and compared the brake lengths when checking the line lengths and trims. Check that length from the tail to cascade, cascade to brake setting, and brake setting to toggle. Also check that the toggles are equal lengths.

    Large loop toggles are useful as they are easier to locate if you have to transition quickly from catching to braking. Ensure that they do not have any catch points as they may tangle in the suspension lines of another canopy. They are also useful in that they mitigate the affects that front risering whilst holding toggles has on rear risers. This is due to the affective lengthening of the distance from the brake setting to the end of the toggle. The other option is to have shorter toggles and a longer brake setting to toggle line length.

Pilot Chute & P/C Retraction System: the important thing is for the bridle to be fully retracted and the pilot chute to be fully depressurised. They must be kept out of the way of other parachutists whilst flying within and near the formation. A well designed retraction system will also minimise the movement of the bridle if the canopy is collapsed. You don't want a bridle flying everywhere during a wrap. The pilot chute needs to be depressurised so that it does not affect the aerodynamics of the canopy or interfere with jumpers and their equipment. The most important consideration for a retraction system is that is should not interfere with the deployment sequence of a canopy.

    The smaller your canopy, the lower the distance between cells. This means that given the same design of retraction system, smaller canopies need to have shorter bridles. There are a few issues to consider here. The length of the bridle needs to be considered in relation to the burble created behind a parachutists back during deployment. An excessively short bridle will be caught in the burble and consequently may not inflate to commence the deployment sequence. If the bridle is too long, then the retraction system may not fully retract the canopy. This will affect the flying characteristics of the canopy. Hence, if you do have a relatively short bridle, you must be extra careful to ensure it is deployed into clean airflow and that you are ready to expose it to airflow (expose your back to airflow) if it suffers burble related issues.

Risers: The risers should be considered in conjunction with line length and trim. For all practical purposes, the risers are an extension of the lines (or visa versa depending on your pursuasion) and add to their total length. Everyone should have the same riser and line length.

Harness Geometry & Setup: the size, setup, and geometry of the harness can affect the flying performance of a canopy. Canopies fly more efficiently when the chest strap is loosened up as it flattens the canopy out across its span. Loose leg straps affectively lengthen the risers. You could also consider the design of particular types of harness and container systems. Their geometry may be different.

Air Resistance: A baggy jumpsuit with a rough surface will create more air resistance than a tight suit made of F111 fabric. A tall large parachutist will have a greater surface area exposed to the relative airflow than a short, slim parachutist. This creates more resistance. You could also consider parasitic drag (types of shoes, headgear, camera gear, line dimensions, frayed canopies - the list is endless). You could consider putting the large person in a tight, smooth jumpsuit and the small person in a baggy jumpsuit. But no we are getting real technical.

Weather Conditions: flying cross wind, versus into the wind, versus with the wind will all affect the formation in various ways. Turbulence will also affect how sections of the formation will fly relative to other sections. The ideal situation is for zero wind and no turbulence.

    How does the wind affect a formation? Lets look at the extreme example of a cross wind flight. The side that is directly exposed to the wind will be hit by a clean and direct relative air flow. As the air flows over these canopies, people and equipment, it gets disturbed and localised pockets of turbulence is created. The canopies that are adjacent to the "clean canopies" may hit with an altered or disturbed air flow. This was result in different flying characteristics. They will be less efficient. This is compounded as you move further into the formation. The canopies furthest away will probably have a higher descent rate due to their inefficiency. Remember that this is an extremely theoretical example.

    What if a large formation is flying above localised sources of thermal activities. If one side of the formation is affected by the thermal and the other remains in clean air, the thermal affected side will tend to suffer rapid changes in pressurisation, descent rates, and forward speeds. This will be transmitted to other parts of the formation due to changes in grip tension throughout the formation.

Calibration: Prior to building large formations, it helps to do a practical test of compatibility. Ideally, you would check each person with every other person on the formation. But this is very impractical. Hence, you can test in groups and then cross test with other groups. For example, if you are building a 16 way diamond. You might choose four 4 way formations. Initially you would choose one member of each 4 way to form a "master group" that "calibrates forward speed and descent rate to one another. They can then go back to their original groups and perform the same calibration. This way, you could have everyone perfectly in sync in only10 jumps. Members of the master group would perform 4 jumps and the others only 2 jumps. You could also choose to just make theoretical calculations and send the whole group up in one go. Given that you usually make a series of jumps from developing the base to building the final formation, it does not hurt to include these compatibility calibrations after break off on each jump.

Problems Associated With Incompatible Equipment: after having considered all the factors above, its important to explain why we are aiming for compatibility. What problems does incompatible equipment give us? Firstly, it makes organisation extremely difficult. Instead of dealing with an already complex equation involving matched wing loadings and airfoils and about 20 variables for the whole formation, you may have to deal with the same complexity level for each member of the formation. That makes a 25 way a potential thesis topic for a Doctorate in Applied Mathematics! And I am not sure how a bunch of CRW dogs are going to fit that into a weekend involving a theory course, practice jumps, tall tales of wraps gone wrong, food, and beer!! But it is possible. Examples of actual issues that occur:

  • Variability in dimensions (line lengths & aspect ratio). A world class team competition CRW Triathlon has much shorter lines than the traditional freefall version. It also has differences in nose design, bridle retraction system, trim, and tail pocket. The PD lightning has shorter lines than most off the shelf Triathlons but they are usually longer than the competition Triathlons. If you put PD Lightnings, competition CRW Triathlons, standard Triathlons, and other models in the same line of a large formation, it will look extremely uneven. This means that the grips taken by this row will force the canopies below to be distorted which will affect the way individual canopies and the formation flies. It is better to have the same type of canopy and line lengths on the same row. If you have variable aspect ratios and spans, this will affect how the complete formation flies. A 115 Lightning next to a 220 Diamant will create major distortion as their widths are markedly different.
  • Descent rates. Both the Diamant and Triathlon have higher descent rates than the Lightning. If you put Lightning's on one side of the formation and Diamant's and Triathlon's on the other, one side will float and the other sink. Again we have distortion and a greater chance of the formation wrapping around. So we have to balance the descent rates on either side of the formation. It might be better to stick these in lock off slots on the lower and outer sides. If your base has a relatively high descent rate and you put the floatier canopies at the bottom of the formation, they will struggle to get into their slots. Build the base with larger, floatier canopies, and place the smaller ones at the bottom. They have a better chance of staying in their setup position and then getting to their slot as the formation builds. But you still have to match wing loadings. If the canopy below you is excessively weighted, it may actually cause pain, strains, and sprains.

Conclusion

    In a perfect world, to achieve all of the above would require a group of robotic clones using equipment built to exactly the same specifications. This requires lots of money and some crazy geneticist or robotic expert. Given that the CRW world is not a sci-fi world as yet, this is hard to achieve. So the realistic objective becomes to get as close as possible given available resources and people.

    Also, given that grip tension, canopy deformation, changing wind conditions, and other variable factors do exist, it means you may have to modify the above approach to allow for the peculiarities of each particular formation. But leave this complex stuff to the dive organisers.


Design, Organisation, & Dive Planning

    Experience has taught us a great deal about how larger formations fly. We also have a great deal to learn about them. We can use what we know to alter the design characteristics of particular sections and positions within a formation. This could include factors such as different sized canopies in certain parts of the formation (larger canopies in the base), front riser trim aids for people on wing slots, and faster canopies in the centre of the formation to ensure they keep up with the wings. Don't forget that as soon as you start introducing variation, the formula becomes extremely complex. This is why we should aim for as much compatibility as possible when designing and building larger formations. The complexity only becomes relevant when the size of the formation becomes very big (say bigger than 9 ways). Otherwise, keep it simple.

    The key to designing larger formations is aerodynamic symmetry.

    The basis or foundation structure is the diamond. This is usually made up of a square number of parachutists. Two squared equals four, 32=9, 42=16, 52=25, 62=36, 72=49, 82=64, 92=81, and 102=100.  If we aim for a number between these, we add parachutists on the tail (plane dock on the bottom lock off), and on the lower wings.


Aircraft Considerations + Spotting

 


Setup, Approach, & Waiting for your Slot Availability (Echelons)

    Awareness and position discipline. Enough said huh?

    There are many canopies moving towards, setting up on, and docking onto the formation. Each person should have had each part of their jump designed for them. Positions include exit, setup, formation slot, break off, and landing. Stick to your designated position unless your safety is compromised. Keep an eye out for other parachutists and do NOT infringe on their area. This is especially relevant whilst waiting on the side of the formation for your slot to appear. Many people move too far out to the side when they try to readjust their setup position. This moves people on their outside further out.

    One of important skills a large formation CRW jumper needs whilst they are waiting for their slot is to be able to maintain their position relative to the formation despite any changes in its movements. This requires experience and knowledge in all primary control inputs (risers and toggles), and combinations thereof. So how do you remain in position? Here are a few tips:

  • get to the right position in the first place in a timely manner.
  • once in position, use control inputs to stay there. Minimise sideways movements such as sashays as you will infringe on other parachutists space.
  • use opposite (cross over) control such as one riser and opposite toggle (warping).
  • you could try a combination stall (rear riser or toggle) / forward surge arrangement. But you lose a little bit of control over you airfoil when doing this.
  • do micro - rotations. These are rotations involving short durations of front risering followed by braking.
  • use the burble of a person in front of you to stay close.
  • a deep front riser input will accelerate you down but may not go forward.
  • snap braking. If you find yourself driving too fast on the formation, a short, sharp stab of the brakes will stop the forward speed without the corresponding increase in relative height that a longer and slower toggle input will give you.

    Unless you are the bottom point of a diamond style formation, never cross the centre line of a formation, stay on your side. If you are locking off a wing, do not get between your wing man and the formation, follow them in.

    Never get behind the camera person, and you should never get in his way. He should reciprocate by respecting and not entering your space unless previously organised.


Docking

    For details about how to dock on a formation, go to the Docking Section. This section is more about the specifics and etiquette of large formation docking.

    It is imperative that you dock in your allotted slot within a reasonable time frame, especially if you are closing/locking off a wing. Have no more than two attempts at your slot. If you don't succeed, get out of the way and allow someone else to take the slot. This is not the preferred option but it is better that leaving the formation un-built or unsymmetrical. Especially if you are closing off a wing.

Wing: apart from pilot, this is the God slot of large formation CRW. Especially if you the outer wing, centre row on a diamond. Time is less critical here but is still important. It is more important that you make a smooth dock. Other wise you will end up coming around the front of the formation and wipe it out. As soon as you have been caught, apply appropriate trim, keep an eye on your canopy relative to the formation, and get ready to catch your lock off.

Lock Off: The ideal way to lock off is to dock smoothly on both legs and have both grips taken up at the same time. Occasionally one of the catchers may not be ready or aware or you may be slightly off centre with your dock. Hence you should consider the following techinques.

  • Wing (outside):  The wing only has one contact point prior to being locked off. This can act as a pivot or hinge if large forces are imposed on that wing. It can also be pulled down which will distort the formation. The safer method in this case is to dock first on the parachutist that is next to the wing. That person is in a more stable position. You will then be "passed" or "walked" over to the wing to complete your lock off. Make your dock in reasonable time to reduce the work load of the wing. It can be physically demanding and instable if a wing is left hanging with one grip for long periods of time. If you are locking off the outer wing, centre row of a large diamond, you must get there in reasonable time and it is even more critical that you make a smooth dock. Do not dock with speed. Wash off any excess speed before you dock on the wing. Do not do a rotations style dock where you approach from a higher position using front risers. You are better off docking from a lower position using a bit of rear riser or toggle to approach. Many a diamond has been funneled by the outer wing lock off pushing the wing into the front of the formation or pulling it down. Pulling it down may make the opposite wing float up and visa versa. This dock is usually made at the top or the side of a formation.
  • Inside: this is the easier lock off slot as both parachutists that you are docking onto are locked in from above. There are no pivot points either so your targeting is a little less critical. This dock is usually made in the centre or the bottom of the formation.

    The formation should be built symmetrically and smoothly. This means that both halves of the formation should built at approximately the same time. There is a balance between getting to your slot quickly and allowing the other side to build. The danger of one side building too quickly is that it will make the formation unsymmetrical, it may cause variable and excessive grip tension, and it may create too many pivot points. It is especially important to allow the base to build first. For example, if you are involved in a 16 way diamond, it should build something like the following sequence:

  1. Base - pin.
  2. 3rd.
  3. 4 way diamond lock off.
  4. 8 way wedge outer wings.
  5. 8 way wedge lock offs.
  6. 9 way diamond lock off.
  7. 16 way outer wings.
  8. 16 way outer wing lock offs.
  9. 16 way lower inner wing lock offs.
  10. Bottom lock off.

    Note that this formation can be built much faster with very experienced parachutists using a technique called merging. This however takes precision and timing and is not beneficial on most large formations as there is usually sufficient time to build sequentially.

    Make sure after you have docked that the correct grips have been taken and that no lines , equipment, or people are tangled. You don't want to find this out on a quick starburst breakoff. Don't accept other docks until this is under control. Incorrect grips may destabilise and unbalance a formation as it is unsymmetrical.

    If a formation is very unstable, it is usually a good idea not to dock onto it until it stabilises. There are exceptions such as a lock off slot on a wing. If in doubt, don't.


Catching

    There are several key factors involved in catching in large formations:

  • minimise the movement in your harness. You should try to maintain a stable body position and allow the docker to fly to you. Don't reach for the docker if you can avoid it.
  • do not catch a parachutist that is flying at a great speed by the formation. It will distort the formation.
  • if you are a wing, do not catch your lock off until the other grip has been taken.
  • as soon as you dock, be aware of the presence of the person who is docking onto you.
  • if you have to pass or walk a person to an adjacent grip, try to do so with your feet. This is more important on the wings and less important on central lock off slots where trimming is not required as often.

Walking: if a person docks off centre, but you do not want to let them go, you can "walk them" into the correct position. This is a better option than passing as you can maintain grips on your toggles and risers whilst moving them into position. Just be sure to make minimal and symmetrical movements in your harness. Be very aware of lines tangling with your feet. Walking involves moving your feet one by one across the canopy. If you are in the centre cell and you want to go to the right end cell, you would take your right foot out, move across one A line and grip it. Them move your left foot one line across, then your right, then. . . . . until you get to your destination on the end cell.

Passing: if you are locked off on both your end cells, you are less likely to need to be on your controls all the time. Hence you could use the passing technique to assist a lock off completion. When a person docks onto you, you use both your hands to hold the top surface leading edge. You release your grip on the side where you want to pass the canopy and take another grip behind your back and then move the canopy towards the other grip. Repeat this process until the canopy is locked off on both end cells.

    Ensure that you have the correct grip and that there are no entanglements of lines, equipment, and bodies.


Flying in Formation

    In a perfect world, the whole formation will fly with the same forward speed. But it is pretty hard to achieve that. Hence, the formation should err on the side of the centre of the formation flying faster than the sides. If the sides fly faster they eventually have nowhere else to go but to pivot back in towards the centre. This is colloquially known as the egg beater. If the centre flies faster, the sides spend all their time trying to catch up.

Pilot: heading control is very important. As is applying the correct amount of brake in order to control forward speed and descent rate. Any small movements from the pilot are amplified down the formation. Hence it is imperative to maintain balance and stability in the harness, and to dampen all of your control inputs. No sudden movements. All adjustments should be controlled and smooth.

Wing: When you first fly this slot it can be very unnerving trying to maintain your composure with the slightest movement of your outer wing towards the centre of the formation. Some people counteract this fear with TMT - Too Much Trim. This places excessive load on the outer wing which translates to distortions throughout the formation. Your canopy will be distorted if you use excessive trim. Because if flies inefficiently in this configuration, it will load the formation. Minimise the amount of trim that you use on wings. Apply some inner brake initially and then some outer front riser if required. If you need more loading, ask your lock of to give some front riser input or other techniqes to load up and slow down your wing. You can also increase your lock offs wing loading by reducing his inflated canopy area. Do this by compressing or blocking off one of his cells.

    The more trim you apply, the more your counterpart on the other side will have to apply. There will come a point where you may be better off leaving the formation. Back to the drawing board if you want another attempt at the jump.

Monitoring: Whilst flying the wing slot, you can monitor the symmetry of the formation by looking at the opposite wing and each of the canopies in between. Ideally, you should all be level. If you can see the outer end cell leading edge of the other wing and the canopy seems to be in front of you and at a higher level than the remainder of the formation, it means it is trying to overtake. This ma be due to its own performance or other factors. Check how much trim your are applying. If you are applying excessive trim, you may be anchoring and increasing the affective loading of your side of the formation. You are creating a situation like a bulldozer. One side slows and the other keeps going. In the end, the only place it can end up is back in on itself. Relax your trim. If you can see the top skin of the other wing, it is too low on you and may be the one applying too much trim, add a little to counteract, but not too much. There may also be a number of other inefficiencies in the formation that could lead to these observations. Bad docks, affects of turbulence, and various other oscillations within the formation.

Centre Lock Off: people in the centre of the formation should maximise their forward speed. This can be achieved by loosening the chest strap a little and arching forward. Monitor the formation around you. If the wings start moving ahead of the centre of the formation arch harder.

Wing Lock Off: keep a constant eye on your wing. If you feel lift being generated on your side of the formation, you should load the wing up by giving some front riser input. You may see this visually when your canopy rises up past the knees of your wing man, or you may feel it. You can also check your level relative to canopies on the same row as yourself.


Break Off

Planned: this is the preferred option as traffic management is easier and risk is much lower.

Starbursts

Unplanned: sometimes canopy formation do funnel and at some stage prior to landing, the members of a formation will have to break off.


Landings

    Traffic awareness and controlled landing patterns are the keys to safety and success when planning the landings for large formation attempts.

    Refer to the landings section for more information.


Large Formation Emergencies

     Refer to the Emergency Section for detailed information about how to deal with particular emergencies. In particular, read about wraps and entanglements. Most of the information relevant to general CRW emergencies is relevant to larger formations. The main difference is that there is potential for a higher number of people to be involved in the emergency which may increase the complexity.

    Maintain awareness throughout the jump and ensure you communicate. Communication in a large formation for most people is about LISTENING, not talking, unless required by safety. Discipline is very important, especially when things do not go to plan. A wild chase of freebags involving 50 canopies can only lead to trouble.

    If you are the pilot and there is a wrap below you, DO NOT LET IT GO unless you are endangered yourself. I must clarify the distinction between endangered and scared. You are not necessarily endangered if you are scared. Dropping a wrap significantly increases the risk to people below you. Attempt to maintain stable, on heading flight for as long as possible.

    If there is a cutaway, its important that a minimum number of people chase the equipment (reserve freebag and main canopy). Maintain traffic awareness around you. Do not catch the main canopy at any time. Only catch the freebag if you are experienced and you know what you are doing. Better still, don't catch it. Just follow it. Ensure that someone follows the reserves too. You never know what state the parachutist may be in after a scary emergency.

    There is a chance that you will land off drop zone in an emergency. Whilst everyone should endeavour to fly back to the designated landing area if possible, it is also extremely important for people to land in groups and not alone. There is always the chance that someone may be or get injured and need immediate assistance. This is true in all off drop zone landings involving any discipline.


Following are notes & other ideas relevant to this section that require further development. Please ignore.

Its imperative to make your dock WHEN the corresponding segment or base ahead of you is completed. Symmetry of formation is critical.

Layers of wind, temperature, pressure, etc need to be considered.

Start with smaller formations and build on them.

Consistent base is imperative.

Larger canopies on top. >160 lightning in 25 way base.

exit 14500ft (4500m) break off 6500ft (2000m)

50 way diamond in 1996 flew fast and most approaches were on rear risers. Speed allowed wings to fly neutral in terms of speed.

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