Charles WARREN
DropMaster Delivery System
http://www.military.com/soldiertech/0,14632,Soldiertech_CopterBox,,00.html
For troops in the field, replenishing supplies can be the biggest hurdle of them all -- a hurdle which may disappear with the help of the new
CopterBox Delivery System.
By David Crane
Editor, DefenseReview.com
Hypothetical Scenario: A U.S. military Special Operations team is currently in the middle of a clandestine op, in-theater. They're running low on 5.56x45mm and 7.62x51mm ammo, magazines, 40mm grenades, food, and medical supplies. One of the team's SOPMOD M4/M4A1 Carbines is down, and they need two extra HK69A1 40mm grenade launchers and a Milkor MGL Mk-1S as force multipliers. As if that's not enough, the local warlord who's been assisting the team against enemy insurgents is now asking for another $500,000 U.S. and a brand new stainless steel Rolex Submariner wristwatch, just like the one he's seen on the wrist of one of the operators.
DefenseReview.com (DefRev) is an online tactical technology magazine that focuses on advanced tactical armament, tactical equipment/gear (including combat/tactical camouflage technology), and tactical training/instruction for military infantry forces. DefenseReview.com strives to provide the most up-to-date information on law enforcement (LE) SWAT/SRT and military Special Operations (infantry)/Special Warfare (SPECWAR) technology developments as quickly as we learn about them.
This team needs a little care package delivered, fast and low-profile. So, they call it in. Five hours later, as the team hangs tight under tree cover, four hexagonal corrugated paper boxes are airdropped from a non-descript utility aircraft at 300 feet. Four low-signature airdrop bundles exit the aircraft. Pilot chutes and rotor blades on all four deploy, which allow them to autorotate down to the ground accurately at less than 40 feet per second. As the containers hit the tree line, the rotor blades slice right through the tree canopy at 400 rpm. The team recovers the payload and extracts the requested goodies. They're back in business, and back in the game.
The airdrop scenario described above is now possible because some creative thinkers at DropMaster, Inc. have come up with CopterBox, an item so simple in concept and design that it's easy to overlook its potential to profoundly change the U.S. military's resupply doctrine and logistics paradigm.
Airdrop It and Forget It
The result of a privately funded 9-year, $450,000 project, CopterBox is an expendable airdrop delivery system specifically designed to deliver a 60-100 lb payload anywhere in the world, anytime it's needed. With CopterBox, you don't need specially trained riggers to rig Mil-Spec cargo parachutes and 200 lb (minimum) pallets for a 60-100 lb payload. And, you don't need a C-17 Globemaster III or C-130 Hercules tactical transport aircraft to airdrop it, or a CH-47D/MH47E Chinook heavy lift helicopter or UH1-Y Huey utility helicopter to land with it. All you need is a single non-specialized soldier to quick-assemble CopterBox, fill it up with the needed supplies, and load it onto any military or civilian aircraft that will hold it. Then, just airdrop it and forget about it. Once it's safely on the ground, a single operator can quickly recover the payload and dispose of the empty system, then get right back to the mission. Quick and easy. Four CopterBoxes dropped means four operators to recover them, and so on.
CopterBox: The Skinny
Name:
DropMaster CopterBox
Type of Equipment:
Airdrop delivery system
Killer Features:
* Can deliver between 60-100 pounds of payload, anywhere,
anytime
* Can be airdropped from any aircraft or helicopter
* Delivery accuracy outshines standard parachute-dropped
supplies
* At $300 per CopterBox, a clear savings compared to standard
cargo delivery systems
MP3 File - British Forces Broadcasting Service (BFBS) interview with Chase Warren, DropMaster Inc.'s Director of Engineering
For more information about CopterBox, or to place an order for it, contact DropMaster, Inc. at 910-630-3269, or by email at copterbox@dropmaster.com
With the U.S. military's current parachute-based system, an open-field airdrop is usually the best way to go, since the chutes and lines can get hung up in the trees. But, an open-field recovery exposes the team. Aside from the rigging and delivery logistics problems, payload recovery with this system can also be physically difficult and time-consuming. A helo drop requires said helo to either hover over the drop zone or land with the risk of airborne sand brownout or foliage-related foreign object damage, plus the added danger of enemy attention. Helicopter flight time spent hovering and landing is very expensive, as is losing the aircraft to hostile fire.
Fortunately, at only $300 per unit, CopterBox makes all this unnecessary. It's even more accurate than parachute-based systems, since wind drift hardly effects its trajectory. The CopterBox's impressive delivery accuracy/minimal wind drift has already been observed in prototype testing from 200 to 10,000 feet above ground level.
And, here's the kicker: with additional developmental funding, CopterBox can be outfitted with a low-drag cardboard fairing and hard points for UAV (or other aircraft) deployment. The CopterBox can also be constructed out of inexpensive corrugated plastic sheet for water-resistance or re-use, per organizational requirement and development funding. Another potential operational benefit is the ability to attach an altimeter or timer delay device to the pilot chute deployment system, allowing CopterBox to be free-dropped from high altitude out of small arms fire reach without the associated long drift time. A larger diameter or taller CopterBox can also be developed with additional funding, and can be scaled to customer/end-user requirements. For instance, a small arms/light weapons-specific version of Copterbox can be developed that will allow delivery of small arms and light weapons to the field, fully assembled. The weapons can be arranged concentrically with internal spacers, to prevent damage. Other versions can be developed to deliver replacement Javelin anti-armor missiles and Predator short-range assault weapons.
The Rotor Blade Deployment Sequence
When CopterBox is deployed from the aircraft, the small drogue chute comes out first. The drogue chute, utilizing mesh in lieu of shroud lines (to prevent tangling and snagging on foliage), orients CopterBox into the relative wind. The chute pulls on the drogue line. This causes a patented break-away stitching system to force a delayed deployment (i.e. opening) of the rotor blades, once CopterBox is safely away from the aircraft. The break-away stitching system also ensures reliable rotor blade deployment.
Once the rotor blades are deployed, they cause CopterBox to spin at 400 rpm and begin the autorotative descent to the target area on the ground, and enable it to cut right through dense foliage on its way down. An added benefit of CopterBox's drogue chute/orientation system is that it negates payload center-of-gravity issues when it's packed and loaded onto the aircraft. It also makes CopterBox easy to locate, since you can color the drogue chute any way you like--even hot pink! Once you recover it, just stuff the brightly colored chute back inside CopterBox.
During touchdown, a paper honeycomb shock absorber plug protects the payload from impact damage. This custom-made honeycomb is tailored to crush from the deceleration of 60 to 100 lbs, unlike the much stiffer Mil-Spec material, which is designed for much heavier payloads. A welded wire rotor hub is at the top of the box, which withstands all of the rotor blade flight and centrifugal loads. The same part is used on the bottom as a landing skid, which protects the box during rigging, shifting around in the aircraft and upon ground impact. After landing, these two items can be used as camp stoves if needed.
So, what's the word on the proverbial street about CopterBox? Word is, to a man, every U.S. military spec-operator who's seen the CopterBox prototype demonstrated is very excited about it, and wants it operational ASAP. PSYOPS personnel are excited about CopterBox's ability to be modified into a psychological warfare tool. CopterBox can be easily and inexpensively modified into a propaganda leaflet dispenser by including centrifugally opened panels on the hexagonal sides, triggered by the aforementioned timer or altimeter. So, as CopterBox spins, the leaflets spin right out, go everywhere, and accurately reach the intended population.
CopterBox Kit
Simplicity itself: The CopterBox kit.
Unfortunately, U.S. military brass have allegedly been dragging their heels on adopting CopterBox. One of the speculated reasons is that CopterBox's extremely low $300 per unit price makes it administratively unattractive, and less of a "larger-ticket item." What should be stressed is that CopterBox is useful and adaptable, and has the potential to become a major program from sheer deployment numbers. As one considers the price of a CopterBox versus the astronomical expense of reusable cargo parachutes (that likely do not get reused) and all of their associated logistical costs, CopterBox's budgetary benefits quickly become clear. It's the author's opinion that our Special Operations personnel need CopterBox, or something like it, right now. So do our U.S. Army and Marine Corps general infantry, for that matter. Non-military applications also come to mind, such as humanitarian relief, domestic disaster relief, and the Forest Service's Smokejumpers.
Dimensions and Specifications:
In its rectangular kit form, which comes in a plastic bag to protect it from the elements, CopterBox occupies a 9" X 18" X 34" space on a shelf or pallet. In its rigged, hexagonal form, it is 34" tall and fits inside an 18" circle. The current product, the model 6036, is designed to hold 60 lbs and 3.6 cubic feet of payload while fitting out of a Cessna 172 test aircraft's door. Although it is designed for 60 lbs, it can handle up to 100 lbs -- albeit at the expense of a higher descent rate, and the ability for a single person to load it into an aircraft and for one operator to easily handle it on the ground. With minimal training and the instruction sheet provided, one person can assemble a loaded CopterBox in about 5 minutes. The instruction sheet has received real world end-user input to maximize clarity and ease of assembly. The patented rotor blades are constructed from high-strength corrugated paper but are folded in a way that provide a high degree of strength and aerodynamic lift. A yardstick-type spar is added for additional strength, as there is an incredible amount of aerodynamic stress on the blades during the deployment and flight sequences.
It should also be noted that DropMaster, Inc. received a 98% rating by the U.S. Army Soldier Systems Center (Natick), on their Phase I efforts on a Small Business Innovation Research (SBIR) grant. DropMaster, Inc. was also invited by Natick to participate in a Phase II grant, two years in a row. However, military funding obstacles have since intervened.
About the Author: David Crane is a military defense industry analyst and consultant, and the owner/editor-in-chief of DefenseReview.com. He can be contacted by phone at 305-389-1721, or via email at david@defensereview.com.
http://www.acq.osd.mil/osbp/sbir/overview/index.htm
CopterBox Expendable Airdrop Delivery System for Ammo, Food, Meds, and More
by David Crane
david@defensereview.com
DropMaster, Inc. has developed a new, expendable airdrop delivery system, called CopterBox. CopterBox is an autorotating, disposable aerial resupply system, and appears to be a superlative, off-the-shelf product. It is specifically designed to be quick to assemble with minimal training, easy to deploy with or without a static line and to be lightweight for a single operator to recover on the ground.
When dropped from an aircraft, CopterBox decelerates a 60 lb payload to about 34 feet per second at sea level. DropMaster's main focus is simplicity and low cost. Since CopterBox is meant to be expendable (it's predominantly biodegradable and/or burnable), you can just drop it and forget it. A patented pilot chute delay system allows CopterBox to fall a safe distance away from an aircraft prior to rotor blade deployment.
After the rotor blades deploy and autorotation begins, the steady-state descent is not affected much by wind drift, unlike parachute-based systems. This minimal wind drift has been observed in prototype testing from 200 to 1,500 feet, resulting in tremendous delivery accuracy. And, because it spins at about 400 RPM, CopterBox cuts through trees and always reaches the ground, again, unlike... parachute-based systems. It is primarily made of high-strength corrugated paper (high-strength cardboard) with minimal metal and nylon parts. These simple materials allow CopterBox to be scalable to customer needs.
With minimal additional cost, a low-drag cardboard fairing can be fitted along with hard points for deployment from UAVs or other aircraft. Pending proper funding, GPS guidance can be achieved for HALO drops where guidance occurs prior to altimeter-triggered rotor blade deployment at a pre-set altitude. CopterBox requires no logistical support or maintenance.
Payload weight is currently limited to 60 to 100 lbs. This allows a single operator to recover the payload and easily dispose of the empty system, so he can quickly carry on with his mission.
If necessary, CopterBox can easily be made from high-strength corrugated plastic sheet (instead of high-strength paper/cardboard), in order to be water-resistant.
Priced at $300 per unit, CopterBox is patented and is the result of a nine year, $450,000 project. It should also be noted that DropMaster, Inc. received a 98% rating by the U.S. Army Natick Soldier Center, a.k.a. U.S. Army Soldier Systems Center (Natick), on their Phase I efforts on a Small Business Innovation Research (SBIR) grant. DropMaster, Inc. was also invited by Natick to participate in a Phase II grant, two years in a row. However, military funding obstacles intervened.
If you need more information about CopterBox, or you would like to place an order for it, please contact DropMaster, Inc. at 910-630-3269, or by email at copterbox@dropmaster.com.
DefenseReview syndicates "Defense Tech" news. "Defense Tech" is published by Noah Shachtman.
DropMaster, Inc.
3600 Abernathy Drive
Fayetteville, NC 28311
copterbox@dropmaster.com
Charles V. Warren, President
(910) 630-2997
US Patent # 5,947,419
September 7, 1999
Aerial Cargo Container
Abstract
An aerial cargo container system for transporting cargo from an aircraft to the ground having a cargo box with a continuous side wall with six rectangular side panels, and rotor blades having stowed positions against alternating box side panels and deployed positions extending outwardly from the box in a generally horizontal plane. Each blade may include a lower panel and an upper panel that has two triangular sections behind the leading edge that forms an aerodynamic camber. The blades are hinged to a rotor hub secured across the top of the box. The upward deployment of the blades is limited by tethers extending from the blades down to a tether attach frame secured across the bottom of the box. The box and blades are preferably formed of corrugated paper or plastic material. The entire unit rotates with the load to create aerodynamic braking and lower cargo to the ground with a minimum of energy being translated to the cargo on impact.
Inventors: Warren; Charles M. (Perry, GA), Warren; Charles V. (Fayetteville, NC)
Current U.S. Class: 244/138A ; 102/384; 102/388; 244/1TD;
244/137.4
Current International Class: B64D 19/02 (20060101); B64D
19/00 (20060101); B64D 1/00 (20060101); B64D 1/02 (20060101);
B69D 001/08 (); F42B 010/60 ()
References Cited --- U.S. Patent Documents:
2324146 July 1943 Frazer
2450992 October 1948 Sanderson
2495486 January 1950 Stevenson
2776017 January 1957 Alexander
2917255 December 1959 Boyd
2969211 January 1961 Saurma
3115831 December 1963 Suter
3168267 February 1965 Ferris
3194519 July 1965 Rhodes
3265136 August 1966 Wojciechowski et al.
3273834 September 1966 Bower
3342439 September 1967 Behrendt
3401906 September 1968 Girard
4890554 January 1990 Schleimann-Jensen
Description
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to an apparatus for transporting cargo from an aircraft to the ground, and in particular to an improved, disposable cargo container comprised of a box with extendible rotor blades that can be dropped from an aircraft to the ground under adverse conditions without damage to the cargo.
(2) Description of the Prior Art
Numerous circumstances require the transport of various kinds of cargo to inaccessible or remote areas where ground transportation is not possible or timely. These circumstances include both military and peacetime conditions, such as providing emergency food, fuel and medical supplies to victims of natural disasters, fighting of forest fires, etc.
In many instances, the cargo can be transported to the area by helicopter, or dropped from an airplane with a parachute. However, helicopters are not always readily available, and are expensive to operate. Parachutes are also expensive, particularly when used to drop relatively small quantities of cargo, and are usually not recoverable due to the terrain and the conditions under which the cargo is dropped.
Various prior art patents, since at least as early as the 1940s, have proposed an alternative means involving the dropping of containers of small cargo loads from an aircraft without a parachute. Instead, the container is constructed of a disposable box with attached wings or rotor blades that extend outwardly when the box is dropped from an aircraft. The force of the air against the lower surface of these blades causes the blades to turn in the direction of their leading edges, rotating the attached box and creating lift to slow the container's descent.
The following patents are representative of these prior art devices:
Patent Number Inventor
2,450,992 Sanderson
3,168,267 Ferris
2,324,146 Frazer
2,495,486 Stevenson
3,115,831 Suter
This alternative transport means, while conceptually addressing the need for inexpensive cargo delivery, has apparently found no significant application. This lack of use is believed to be attributable to two somewhat related reasons; cost effectiveness and durability. In order for this type of devise to find a niche in cargo transport, the cost must be low since the container is not recovered. However, prior art designs that could be produced at an acceptable cost do not have the durability to withstand the destructive forces to which they are subjected, resulting in failure of the systems to get their load to the intended destination undamaged. However, the need remains and the basic concept is appealing. Therefore, a disposable aerial cargo container that could be manufactured at an acceptable cost while still having the required strength and durability should be of considerable utility.
SUMMARY OF THE INVENTION
The following summary describes an improved aerial cargo container useful in transporting cargo from an aircraft to the ground. This cargo container incorporates features not suggested by the prior art that enable production of the container at an acceptable cost, while still providing the strength and durability necessary for transportation of cargo loads of sixty (60) pounds or more under adverse conditions without significant damage to the cargo upon impact with the ground.
Essentially, the performance of the cargo container of the present invention is attributable to various modifications and refinements of cargo containers of the type described in the above prior art. That is, the present container, like prior art containers, is comprised of a box for holding the cargo to be transported, and a plurality of wings or rotor blades having hinged roots, with the blades being deployable to a substantially horizontal attitude when the container is dropped from the aircraft. As with prior art containers, air pressure against the rotor blades causes the box to rotate and create aerodynamic lift to slow the descent of the container.
The cargo container of the present invention, however, incorporates various features not suggested by the prior art. These improvements reside in the following three areas: 1) the box or cargo holder construction and blade positioning, 2) attachment of the rotor blades, and 3) the rotor blade construction. Each improvement contributes to the economical construction of the container and to its superior performance. Depending upon the particular container and its uses, these features may be used alone or in combination.
The configuration of the cargo box and the placement of the rotor blades thereon can dramatically affect various aspects of the container including its carrying capacity, its durability, and its cost of manufacture. It has been determined that the preferred cargo box addressing these concerns is a box with a hexagonal cross-section comprised of a continuous side wall formed of six rectangular attached facets that are positioned in a hexagonal configuration, and a hexagonal end wall closing one end of the box formed by the side wall material. The open end of the container is closed with a hexagonal shaped plug type lid to enclose the cavity.
The box walls, for purposes of disposability and economy, are preferably formed of corrugated paper or hardboard. The continuous sidewall may be formed of a single sheet with spaced creases to form the individual panels. The abutting ends of the sheet are joined, e.g., by taping, staples or glue. Alternatively, the sidewalls can be formed of six rectangular panels that are joined to each other at their abutting side edges. The size of the box will depend upon the type of cargo to be transported and the cargo size and weight. Generally, however a box with a length from about 32 to about 36 inches and a diameter from about 15 to about 18 inches will be suitable for most cargo up to a weight of about 60 pounds. Thus, each side panel will have a length of from about 32 to about 36 inches and a width of from about 15 to about 18 inches.
The container includes three rotor blades, with each blade being positioned adjacent to alternating side panels. Thus, a container formed of six side panels will have three rotor blades, with one blade adjacent to every other panel. When the container is stowed, the rotor blades are folded against the side panels and, when deployed, extend outward from the box in a substantially horizontal plane substantially perpendicular to the side panels. In order to achieve maximum lift, while still being easy to store, the blades preferably have length and width dimensions approximating the corresponding dimensions of the side panels.
In prior art disposable cargo containers, rotor blades have been hinged at their root to one panel or side of the container box. Since disposable boxes, of economic necessity, are usually made of corrugated paper, or another disposable material with low tear strength, forces against the rotor blade caused by air pressure and the centrifugal force tends to rip the hinge, and often part of the box. Separation of one or more rotors during flight can be disastrous to the load since the container will probably plummet to the ground, damaging the cargo.
In the present invention, this deficiency has been addressed by the use of a separate rotor blade hub positioned at the closed (upper) end of the box, with the rotor blades being hinged at their roots to the hub, instead of directly to the box. Preferably, the hub is in the shape of a metal wire frame that extends over the top and upper edges of the box. The rotor hinge points on the hub are located on the support adjacent alternating box panels, with hinge pins being used to attach the rotor blades to the hinge points of the hub. Thus, the centrifugal force exerted by the blades act upon each other through the hub and not the box. Preferably, the hub includes a common central point with connections from the central point to each of the hinge points. With this arrangement, the rotor blade's centrifugal forces tend to act against each other to negate the stresses and loads on the box.
Upward movement of the blades during deployment and flight is limited by tethers and shock cords having their upper ends attached to the blades and their lower ends attached at the lid (lower) end of the box. The tethers may be resilient, such as a bungee cord, or a non-resilient cord of a material such as nylon.
The lower ends of the tethers can be attached directly to the box. However, since the tethers are also subjected to high forces, particularly during deployment, the box preferably includes a tether attachment frame that extends across the bottom wall (lid). This tether attachment frame includes attachment points to secure the lower end of each tether approximately beneath the rotor blade to which the upper end of the tether is attached. For example, the attachment frame can be in the shape of an equilateral triangle having apexes that extend beyond the periphery of the box under the alternating panel over which the panels are positioned, with one tether being attached at each apex of the triangle.
Prior art rotor blades for expensive devices have been made of metal or wood. However, rotor blades for containers designed for the purpose of the present invention, have been made from a planar piece of corrugated paper or polymer to reduce cost. These latter blades are not of sufficient strength to withstand the forces to which the container is subjected or to create significant aerodynamic braking due to lift. The present invention solves this problem with a rotor blade that is made from a single corrugated material sheet or a plurality of segments joined in a particular manner to provide the needed structural integrity under incurred aerodynamic and centrifugal loading, while maintaining the required economy.
Basically, the improved rotor blade is comprised of a lower facet, and a multi-facet upper panel secured to the lower panel to form an integral blade. The lower panel is essentially planar and of a single facet, with leading and trailing edges, which may have constant or varying chord distance between them along the span of the blade. Together, the panels form a blade having a planar bottom surface, and a top surface that includes an upwardly extending forward triangle adjacent to the leading edge of the blade and a planar surface extending downwardly and rearwardly from the forward triangular section aft to a point forward of the trailing edge, forming and aft triangular section. A pocket for a structural spar exists between these two triangular sections.
To form the forward triangular section, the front segment is inclined upward and back from the leading edge of the blade. A generally vertical forward spar pocket segment has an upper edge common to the rear edge of the upper forward segment of the forward triangular section, and a lower edge abutting the lower panel.
The center segment spar pocket common to the upper panel has a front edge adjacent and parallel to, but not necessarily abutting, the rear edge of the front segment, and is inclined to the rear and down to a rear edge that also abuts the lower panel. A generally vertical spar has an upper edge integral with the front edge of the center segment, and a lower edge abutting the lower panel.
The rear segment of the upper panel is generally planar and abuts the upper surface of the lower panel, and has a front edge integral with the rear edge of the spar pocket and a rear edge integral with the rear edge of the lower panel.
The lower and upper facets of the rotor blade can be made from a single corrugated material that is folded along the longitudinal axis of the blade to form the panel segments. That is, the blade can be formed by longitudinally folding the outer sides of a paper sheet over a planar central section that forms the lower panel. One side of the sheet is creased to form the front segment and forward spar pocket segment, while the other side of the sheet is folded to form the rear and central segments of the upper panels, and the aft spar pocket segment.
A folded piece of corrugated material is inserted in the spar pocket and forms the spar. The top of the spar is even with the top of both the forward and aft triangular segments. The spar translates the aerodynamic forces to the tether and the box. The front and central segments of the upper panel, supported by the spar and the spar pocket, form a raised triangular section along the top of the blade parallel to the blade's longitudinal axis and adjacent the blade's leading edge. This triangular section forms the structural rigidity of the rotor, as well as providing the aerodynamic camber required to generate lift.
The tether is attached to the spar in such a way to translate all of the aerodynamic lift and planar drag to the box from the rotor blade. The upper end of the tether can extend through the blade's lower facet and around the spar and spar pocket, and then back through the lower facet to form a loop.
The box is designed to be loaded upside down. That is, the lid end of the box that will be in a down position when the box is in flight will be oriented upward during loading. For this discussion, box orientation convention will be rotor hub end down and lid end up. Thus, when assembled and oriented for loading, the box has a continuous sidewall formed of six adjacent, rectangular side panels, and a lower hexagonal end wall secured across the rotor hub end of the box. The box is inserted into the rotor hub, which forms a base or skid upon which the container rests. The rotor blades are attached at their root hinge points, to the support, and are folded up against the sidewalls of the box. A breakaway strap or other means of sacrament is used to hold the blades in their folded position during loading and transport to the drop zone.
When loading, a spacer may first be inserted into the container. This spacer serves two purposes. First, the spacer prevents cargo from being loaded into what will become the upper end of the container after deployment, thereby ensuring that the center of gravity of the box will be near the centroid of the cavity to ensure positive blade deployment. Also, the spacer, which can be of an expanded material, such as honeycomb paper, can absorb some of the shock of loading and carriage in the aircraft.
After the payload is centered and chocked with disposable packing along the vertical axis of the box, the hexagonal plug lid is secured in the open end. This lid is constructed of honeycomb or expanded material which will tend to crush upon landing, absorbing shock and dissipating the deceleration forces. The tether attach frame is placed over the lid and strapped into place with a packing strap that runs around the rotor hub and the entire box. The strap will hold the lid, the tether attach frame, and the rotor hub in place on the box until the aerodynamic and deceleration loads can hold the assembly together in flight. Once the box has landed, the strap is removed to unpack the payload.
The loaded container is then placed in the same orientation in which it was loaded in an aircraft and flown to the drop area. The box is pushed from the aircraft over the drop zone with a static line or other mean removing the blade-restraining strap that allows the blades to deploy. The relative wind around the box causes a lifting force to deploy the rotor blades which rotate about their hinge attach points and are snubbed by the tethers and the shock cords. The blades will be limited to a substantially horizontal orientation, i.e. plus or minus ten (10) degrees of horizontal by the tethers. In turn, the tether attach frame absorbs the tension in the tethers instead of the box.
The force of the air against the lower facet of the blades, with the leading edges of the blades being lower than their trailing edges, causes the container to rotate in the direction of the leading edges, and accelerate rotationally until it achieves rotational terminal velocity, generating maximum aerodynamic lift, thereby slowing the box to its terminal vertical velocity. Centrifugal forces acting on the blades that heretofore could cause the blades to rip from the box during deployment and rotation are absorbed by the rotor hub.
The triangular facets of the rotor blades creates an aerodynamic camber and form structural box beams to insure rotor blades stiffness until centrifugal force stiffening can assist the structure during maximum deceleration. This slower rate of descent minimizes damage to cargo upon impact of the container with the ground. The crushable shock-absorbing lid further lessens the risk of damage to the payload.
Accordingly, one aspect of the present invention is to provide an aerial cargo container comprising a box having a continuous side wall formed of six rectangular side panels, an upper end wall at one end of the side wall and a lower end wall at the opposite end of the side wall, the walls forming a cargo cavity; and three rotor blades having hinged roots, the blades having a stowed position against alternating side panels and a deployed position extended outwardly in a generally horizontal plane.
Another aspect of the present invention is to provide an aerial cargo container comprising a cargo box having a continuous side wall, a first end cap and a second end cap; a rotor hub across the first end cap; and a plurality of rotor blades having leading and trailing edges, and root hinged to the rotor hub, the blades having a stowed position against the box and a deployed position extending outwardly from the box in a generally horizontal plane.
Still another aspect of the present invention is to provide an aerial cargo container comprised of a cargo box with a plurality of rotor blades with leading and trailing edges, each of the blades having a stowed position against the box and a deployed position extending outwardly from the box in a generally horizontal plane, the blades being formed of corrugated material and having a planar lower surface and an upper surface that includes triangular raised sections adjacent the leading and trailing edges.
Another aspect of the invention is to provide an aerial cargo container comprising of a box having a continuous side wall formed of six rectangular side panels, an upper end wall at one end of the side wall and a lower end wall at the opposite end of the side wall, the walls being constructed of corrugated material and forming a cargo cavity; three rotor blades having leading and trailing edges, and inner root ends, the blades having a stowed position against alternating side panels of the side wall and a deployed position extending outwardly from the box in a generally horizontal plane, each of the blades consists of a lower panel and an upper panel, made up of two triangular boxes, a spar pocket and a spar. The front triangular box is adjacent to the leading edge of the blade, the rear triangular box is adjacent to the trailing edge, abutting the lower panel, and the central section between the two triangular boxes consisting of the spar pocket and the spar contained therein; a rotor hub across the first end wall, the root ends of the blades being hinged to the hub; a tether attach frame across the second end wall; and blade tethers attached to the blade spars to the tether attach frame.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the upright and deployed
cargo container as if it were in flight.
FIG. 2 is sectional side view of one of the rotor blades showing the tether attachment.
FIG. 3 is a top view of the container showing the rotor blade root hinges.
FIG. 4 is a bottom view of the container showing the tether attach frame and plug lid.
FIG. 5 is a sectional side view of the container in the loaded and stowed position.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, terms such as horizontal, upright, vertical, above, below, beneath, and the like, are used solely for the purpose of clarity in illustrating the invention, and should not be taken as words of limitation. The drawings are for the purpose of illustrating the invention and are not intended to be to scale.
As best shown in the drawings, a preferred embodiment of the container includes a box, generally 10, a rotor hub 12, three rotor blades 14, a tether frame 16, and strut tethers 18.
Box 10 is formed of six rectangular side panels joined at their abutting edges to from a continuous sidewall 20. An upper hexagonal end wall 22 closes the upper end of wall 20 and a lower hexagonal honeycomb plug lid 24 closes the opposite end of wall 20. A load spacer 28 is inserted into the interior of box 10 adjacent wall 22 during loading of box 10 to position the payload closer to the centroid of the box
Rotor hub 12 is formed of a lightweight welded wire or extruded plastic cage extending across end cap 22 and around the upper ends of wall 20. Hub 12 is strengthened by the use of a central plate 30 and three triangular sections 32 with their apexes welded or formed to plate 30 and their bases adjacent the upper ends of alternating side panels of wall 20.
Blades 14 are hinged at their roots to hub 12 with hinge pins 34, which extend through hinge points 36 extending from hub 12 on alternating sides. In order for the box to rotate and create aerodynamic lift, the chord line of each rotor blade is set at a negative angle of incidence from a horizontal line that is parallel to the end cap 22. This angle creates rotative forces that spin the entire assembly. The angle of incidence is between minus four (-4) and minus six (-6) degrees. At the lower end of the container, a tether frame 16 extends across plug lid 24. Tethers 18 extend from the tether frame 16 to approximately the mid-span of each rotor blade 14.
As shown in FIG. 2, each rotor blade 14 consists of a folded corrugated material that forms a lower panel 38, an upper panel comprised of a front segment 40, a spar pocket 46, a trailing segment 42, a rear segment 44, and a spar 48 inserted and bonded into the spar pocket formed by 46. Each blade of the preferred embodiment is formed of a single corrugated piece, with the corrugations being parallel to the span of the blade. A hinge tube 50 is attached to the root of each blade by a root re-enforcement plate or strap 52. Plate 52 stiffens the blade root and helps to translate the centrifugal and twisting forces to hub 12.
The container is positioned as shown in FIG. 5 when being loaded and transported. Spacer 28 is inserted into the container cavity, followed by the cargo (C). After loading, the plug lid 24 and tether attachment plate 16 are secured in place with a strap assembly 54 by securing the hub 12 and frame 16 to the box 10. Tethers 18 from each rotor 14 are attached to attach frame 16. The rotors 14 are secured with rotor containment strap 54. The box is loaded in the aircraft and the blade containment system is attached to the blade deployment static line in the aircraft. The box is pushed out of the aircraft and blade containment strap 54 is released, causing all three blades 14 to be deployed into the relative wind. The box starts to rotate, generating aerodynamic braking forces by generating lift. This aerodynamic lift is translated through the struts to the tether attach frame 16 which then directs the force through the plug lid 24 to the cargo (C). This force will stabilize when the box and load decelerate to the terminal velocity. This is the minimum velocity the box achieves before landing.
Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the follow claims.
US Patent # 6,712,317
March 30, 2004
Aerial Cargo Container with Deceleration and Orientation Assembly
Abstract
An aerial cargo container is described that includes a cargo box with a plurality of hinged rotor blades having a stowed position against the sides of the box and a deployed position extending outwardly from the box, and a deceleration and orientation assembly to slow the descent of the container and align the longitudinal axis of the container with the relative wind direction, thereby minimizing damage to the blades upon opening. The assembly includes a drogue chute, a blade retainer to secure the blades in the stowed position, and a folded metering cord attached between the drogue chute and the box, and a segment securing the blade retainer, whereby the cord segments unfold sequentially upon exertion of a force to slow and orient the container, prior to release of the blade retainer to permit movement of the blades to their deployed positions.
Inventors: Warren; Charles V. (Fayetteville, NC),
Fitzgerald; Charles G. (Cameron, NC)
Current U.S. Class: 244/138R ; 244/142; 244/147
Current International Class: B64D 1/00 (20060101); B64D
1/08 (20060101); B64D 19/00 (20060101); B64D 001/08 ()
Field of Search: 244/138R,142,147,148,149,150 102/386
References Cited --- US. Patent Documents:
2440293 April 1948 Stanley
3333643 August 1967 Girard
3362665 January 1968 Larsen et al.
3497168 February 1970 Finney et al.
3540684 November 1970 Snyder
3586257 June 1971 Zelinskas
3662978 May 1972 Hollrock
3838940 October 1974 Hollrock
4017043 April 1977 Barzda
4131392 December 1978 Barzda
4379534 April 1983 Miller et al.
4765570 August 1988 Herndon
5232184 August 1993 Reuter
5263663 November 1993 Widgery
5309412 May 1994 Bourgeois
5947419 September 1999 Warren et al.
6164594 December 2000 Pignol et al.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to an improved, disposable cargo container comprised of a box with extendible rotor blades that can be dropped from an aircraft to the ground, and in particular to a disposable cargo container that includes a mechanism for decelerating and orienting the container before extension of the rotor blades, thereby reducing the possibility of damage to the container.
(2) Description of the Prior Art
Numerous circumstances require the transport of various kinds of cargo to inaccessible or remote areas where ground transportation is not possible or timely. These circumstances include both military and peacetime conditions, such as providing emergency food, fuel and medical supplies to victims of natural disasters, fighting of forest fires, etc.
In many instances, the cargo can be transported to the area by helicopter, or dropped from an airplane with a parachute. However, helicopters are not always readily available, and are expensive to operate. Parachutes are also expensive, particularly when used to drop relatively small quantities of cargo, and are usually not recoverable due to the terrain and the conditions under which the cargo is dropped.
Various prior art patents since at least as early as the 1940s have proposed an alternative means involving the dropping of containers of small cargo loads from an aircraft without a parachute. Instead, the container is constructed of a disposable box with attached wings or rotor blades that extend outwardly when the box is dropped from an aircraft. The force of the air against the lower surface of these blades causes the blades to turn in the direction of their leading edges, rotating the attached box and creating lift to slow the container's descent.
This alternative transport means, while conceptually addressing the need for inexpensive cargo delivery, has apparently found no significant application. This lack of use is believed to be attributable to two somewhat related reasons; cost effectiveness and durability.
A disposable aerial cargo container that addresses these prior art deficiencies, i.e., a container that can be manufactured at an acceptable cost while still having the required strength and durability necessary for transportation of cargo loads of up to about sixty (60) pounds or more under adverse conditions without significant damage to the cargo upon impact with the ground is described in U.S. Pat. No. 5,947,419, issued Sep. 7, 1999 to Warren et al., and incorporated herein by reference.
The Warren et al. container, like prior art containers, is comprised of a box for holding the cargo to be transported, and a plurality of wings or rotor blades having hinged roots, with the blades being deployable to a substantially horizontal attitude when the container is dropped from the aircraft. As with prior art containers, air pressure against the rotor blades causes the box to rotate and creates aerodynamic lift to slow the descent of the container. The preferred Warren et al. container includes a cargo box with a hexagonal cross-section comprised of a continuous side wall formed of six rectangular attached facets that are positioned in a hexagonal configuration, and a hexagonal end wall closing one end of the box formed by the side wall material. The open end of the container is closed with a hexagonal shaped plug type lid to enclose the cavity. Alternatively, both ends of the box can be closed and the plug placed inside the box to act as a crushable or frangible cushion of landing. The box walls, for purposes of disposability and economy, are preferably formed of corrugated paper or hardboard.
The preferred Warren et al. container includes six side panels with three or more rotor blades, one blade adjacent to every other panel depending on the number of blades used. When the container is stowed, the rotor blades are folded against the side panels and, when deployed, extend outward from the box in a substantially horizontal plane substantially perpendicular to the side panels. In order to achieve maximum lift, while still being easy to store, the blades preferably have length and width dimensions approximating the corresponding dimensions of the side panels.
While the rotor blades may be hinged at their root to one panel or side of the container box, there is a risk of separation of one or more rotors during flight, causing the container to plummet to the ground, damaging the cargo. In the Warren et al. invention, this deficiency is addressed by the use of a separate rotor blade hub positioned at the closed (upper) end of the box, with the rotor blades being hinged at their roots to the hub, instead of directly to the box. Preferably, the hub is in the shape of a metal wire or composite material frame that extends over the top and upper edges of the box. The rotor hinge points on the hub are located on the support adjacent alternating or sequential box panels, with hinge pins being used to attach the rotor blades to the hinge points of the hub. Thus, the centrifugal force exerted by the blades act upon each other through the hub and not the box. Preferably, the hub includes a common central point with connections from the central point to each of the hinge points. With this arrangement, the rotor blade's centrifugal forces tend to act against each other to negate the stresses and loads on the box.
Upward movement of the blades during deployment and flight is limited by tethers and shock cords having their upper ends attached to the blades and their lower ends attached at the lid (lower) end of the box. The tethers may be resilient, such as a bungee cord, or a non-resilient cord of a material such as nylon. Since the tethers are also subjected to high forces, particularly during deployment, the box preferably includes a tether attachment frame that extends across the bottom wall (lid). This tether attachment frame includes attachment points to secure the lower end of each tether approximately beneath the rotor blade to which the upper end of the tether is attached. For example, the attachment frame can be in the shape of an equilateral triangle having apexes that extend beyond the periphery of the box under the alternating panel over which the panels are positioned, with one tether being attached at each apex of the triangle. Alternatively, a hub similar to the rotor hub can be placed on the bottom of the container to protect the box during handling and serve as a multiple (up to six) attach points for the tethers for all the blades.
Unlike earlier prior art rotor blades of metal or wood, the Warren et al. rotor blades are made from a planar piece of corrugated paper or polymer, either in the form of a single corrugated material sheet or a plurality of segments joined in a particular manner to provide the needed structural integrity under incurred aerodynamic and centrifugal loading, while maintaining the required economy. Each rotor blade is comprised of a lower facet, and a multi-facet upper panel with a multi-faceted forward section, a rotor spar of wood or other material, and a generally planar rear section secured to the lower panel to form an integral aerodynamically-shaped blade.
When loaded, the rotor blades are held against their respective box facets by a blade restraining strap. At the drop zone, the box is pushed from the aircraft with a static line or other means removing the blade-restraining strap. The relative wind around the box causes a lifting force to deploy the rotor blades which rotate about their hinge attach points and are snubbed by the tethers and the shock cords. The blades will be limited to a substantially horizontal orientation, i.e. plus or minus ten (10) degrees of horizontal by the tethers. In turn, the tether attach frame absorbs the tension in the tethers instead of the box. The force of the air against the lower facet of the blades, with the leading edges of the blades being lower than their trailing edges, causes the container to rotate in the direction of the leading edges, and accelerate rotationally until it achieves rotational terminal velocity, generating maximum aerodynamic lift, thereby slowing the box to its terminal vertical velocity.
While the Warren et al. cargo container is a significant improvement over prior art containers, there is still a risk of damage to the container and its contents when the container is released from the aircraft, particularly with heavy and asymmetrical loads or when the container is being deployed in high relative winds (airspeeds). As noted above, the rotor blades in the Warren et al. container are released for movement to their deployed or extended position from their stowed position as the container is released from the aircraft. As a result, the blades extend while the container is dropping rapidly, exerting considerable force on the blades and the hinged attach points. After the blades are fully extended and the container is rotating, the container will orient so that an equal force is exerted on all blades. However, when the container is dropped from a moving aircraft, the orientation of the container may be such that unequal blade forces are exerted. These unequal forces, particularly if the container is moving at a high rate of speed, may cause damage to one or more rotor blades, or prohibit their deployment.
Thus, the utility of containers constructed similar to the Warren et al. container, would be considerably enhanced, and the risk of damage decreased, if the container could be oriented and its descent slowed prior to deployment of the rotor blades. By slowing the container prior to blade deployment, the container will be farther away from the drop aircraft, insuring that the container is not struck by the aircraft.
SUMMARY OF THE INVENTION
In general, the desired results of the present invention are achieved by adding a deceleration and orientation assembly, also referred to herein as a delay assembly for brevity, as described herein in detail, to cargo containers of the type that include a cargo box with hinged blades having a stowed position against the box and a deployed position extending outwardly from the box.
The delay assembly of the present invention is generally comprised of an air resistance device, such as a drogue chute; a blade retainer adapted to secure the rotor blades in their stowed position; and a folded metering cord that has one end attached to the resistance device, an opposed end attached to the top of the container, and a segment attached to the blade retainer. Preferably, the metering cord includes a plurality of folds that are adapted to unfold in sequence.
When loading the container, the bottom cage or hub with the respective blade tethers and rotor blades attached is placed on the floor. The box is inserted into the bottom cage in its hexagonal shape and the frangible plug is inserted into the box. The payload is placed in the box on top of the plug and secured in the center of the box with packing and dunnage. The top wall of the box is closed and the rotor hub cage is placed over the top of the box. The top and bottom hubs are strapped together to maintain their relative position with each other with the box in between them. The rotor blades are then pinned in place to the rotor hinge clips on the upper hub and secured. The delay assembly and blade retaining strap is then attached and secured for transport to the aircraft for launch.
When the cargo container is discharged from the aircraft, the drogue chute or other drag device, e.g., a streamer, exerts a drag due to wind resistance, creating tension on the metering cord, sequentially opening folds of the cord, thereby slowing the descent of the container. At the same time the cord tension orients the container so that its axis is aligned with the wind direction. Following deceleration and orientation, the blade retainer is released permitting the rotor blades to open to their extended position. Since the container is moving at a slower speed, and since the force of the air is approximately equal against all of the blades, all rotor blades will deploy. Thus, the risk of damage is substantially reduced.
In a preferred embodiment, the metering cord is folded into an a plurality if S-type folds, with the folds being secured by thread that has a breaking strength below the force exerted on the metering cord during deceleration, e.g., about 15 pounds force to about 30 pounds force. The number of thread loops securing the folds is equal to twice the number of folds, with the upper or outer fold being engaged by one thread loop and each half sequential fold being engaged by a one additional thread loop. The lower fold, used to secure the blade retainer is sewn with all thread loops and therefore the last to break.
When a force exceeding the breaking strength of the thread is exerted on the cord, the single loop holding the outer fold is broken, allowing the outer fold to open. As a result, a brief drop in restraining force against the container is followed by an increased force, or tug, acting to decelerate and orient the container. The continuing force on the cord then causes the second loop to break, allowing the next fold to open with a similar effect. This sequence continues until the final thread holding the lower elongated fold is broken, resulting in pulling of the elongated fold from the blade retainer, and permitting the blades to open.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a cargo container with the metering assembly.
FIG. 2 is perspective view of the upper end of a deployed cargo container illustrating the open housing and extended cord.
FIG. 3 is a sectional side view of a folded and tied metering cord.
FIG. 4 is a top view of a cargo container illustrating attachment of the cord to the hub.
FIG. 5 is a perspective view of the deployed container during descent with the attached drogue chute.
DETAILED DESCRIPTION OF THE INVENTION
In the following description, terms such as horizontal, upright, vertical, above, below, beneath, and the like, are used solely for the purpose of clarity in illustrating the invention, and should not be taken as words of limitation. The drawings are for the purpose of illustrating the invention and are not intended to be to scale.
The preferred embodiment of the present invention will be described in the context of the Warren et al. container discussed above. It will be understood, however, that the delay assembly can also be used with other cargo containers, as well as with other items that are deployed aerially without a parachute in lieu of static line systems now in use.
As best shown in the drawings, a preferred embodiment of the invention is comprised of a cargo container, generally 10, having a delay assembly, generally 12, positioned on the top of container 10. Container 10 is comprised of a box 14 formed of six rectangular side panels joined at their abutting edges to from a continuous sidewall, a rotor hub 16 formed of a lightweight welded wire or extruded plastic cage, three rotor blades 18, a lower hub 20 similar in construction to hub 16, and strut tethers 22 joining blades 18 to hub 20. Blades 18 are hinged at their roots to hub 16 with hinge pins 24. In order for the box to rotate and create aerodynamic lift, the chord line of each rotor blade is set at a negative angle of incidence from a horizontal line that is parallel to the end cap 22. This angle creates rotative forces that spin the entire assembly. Different airfoil shapes may need different angles of attack. For example, the angle of incidence may be between minus four (-4) and minus six (-6) degrees. Tethers 22 extend from tether frame 20 to approximately the mid-span of each rotor blade 18.
Delay assembly 12 is comprised of a flexible metering cord 30 that is folded as shown in FIG. 3 prior to deployment and held in the folded condition by breakable threads 32, a drogue chute 34, and a housing 36, which may be a cardboard box, to enclose cord 30 and chute 34 prior to deployment. Blade retainer 38 is stretched around box 14 and blades 18 and secured by a segment of cord 30. Cord 30 is formed of a flexible material, such as nylon webbing or a nylon cord that will not break under the conditions of use. Cord 30 will normally have a length of from about 15 feet to about 30 feet for use with most containers.
As best illustrated in FIG. 3, cord 30 is initially folded into a plurality of folds, i.e., an outer fold 40; an elongated inner fold 42, which serves to secure blade retainer 38; and one or more intermediate folds 44 between folds 40 and 42. For ease of packing, and to facilitate a uniform deployment, outer fold 40 and intermediate folds 44 are generally of the same size, while inner fold 42 will be of a length sufficient to engage blade retainer 38. For purposes of discussion, it will be understood that each "fold" is formed of two adjacent, overlapping cord segments.
As will be discussed in greater detail hereinafter, it is desirable for the cord folds to open sequentially during deployment, with outer fold 40 opening first, followed by each intermediate fold 44 beginning with the intermediate fold closest to outer fold 40, and finally inner fold 42. To achieve this sequential opening, the folds are joined by a plurality of thread loops that will break when subjected to the forces of deployment. Specifically, an outer thread loop 50 joins all of the folds together. An inner thread loop 52 joins only the segments of inner fold 42, and intermediate thread loops 54 join each intermediate fold 44 to lower fold 42 and all folds between the particular intermediate fold and the lower fold. Supplemental breakable threads 56 and 58 may be used to secure the outer ends of folded cord 30 until deployment. By duplicating the thread stitch pattern from the inner fold to the outer fold loop pattern, additional break points can be used to increase the amount of brake tugs imparted to the container, thereby slowing down the container prior to lade deployment.
Thus, the folds open sequentially when a pulling force is exerted between the ends of cord 30, beginning with outer fold 40. That is, outer thread loop 50 initially breaks, since thread loop 50 is the only thread loop securing outer fold 40. Then, since fold 44 is secured by only one thread loop, the thread loop 54 breaks. This sequential breakage and extension of cord 30 continues until inner thread loop 52 is broken, allowing inner fold 42 to be pulled from blade retainer 38.
Outer end 60 of cord 30 is attached to a drag device, such as drogue chute 34, with inner end 62 being attached to the top of cargo container 10, e.g., at the center of rotor hub 16. Folded cord 30 and drogue chute 34 are packaged within housing 36. Housing 36 includes an first or upper access opening 66 to permit removal of drogue chute 34 and cord 30, a second or bottom access opening 68 that is opened to withdraw inner end 52 of cord 30 for attachment to hub 16, and a third or side access opening 70 to withdraw inner loop 42 to secure blade retainer 38. Each opening may be covered by a flap or other cover prior to use.
Blade retainer 38 in the preferred embodiment is comprised of a stretchable band or strap, e.g., a bungee cord that is stretched around box 14 and all blades 18 to secure blades 18 in a stowed position against the sides of box 14. The ends of retainer 38 are held together by inner fold 42. For example, as illustrated in FIG. 4, the opposed ends of retainer 38 may include closed loops 74 and 76, with loop 74 being inserted through loop 76 and the end of inner fold 42 being inserted through loop 74.
When cargo container 10 is to be dropped from an aircraft, the operator opens the flap or lid covering opening 66 of housing 36 and removes chute 34. Container 10 is then pushed or thrown from the aircraft. To ensure opening, chute 34 may be briefly held by the operator or by a breakable static line. As container 10 begins to fall, the force of air resulting from the forward and downward movement of container 10 opens chute 34, causing a force to about 30 pounds or more to be exerted on cord 30, causing folds 40, 44 and 42 of cord 30 to sequentially open. Each loop break meters the stowed cord and imparts a pull to decelerate and orient container 10 so that the longitudinal axis of container 10 aligns with the direction of movement. Finally, thread loop 52 securing inner fold 42 is broken, resulting in inner fold 42 being pulled from blade retraining strap 38. As a result, blades 18 are released to move outwardly to their extended positions. Thus, when blades 18 extend, the speed of container 10 has become oriented at the correct attitude and its descent slowed. Therefore, an equal and reduced force is exerted on all blades, significantly reducing the possibility of damage on one or more of the blades.
Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.
