Gertrude and Francis Rogallo together discovered a deep essence of wings, nearly the ethereal most minimal aspect of what wing means; he sought the minimal entrance of wing into materialization. Francis was a professional degreed aeronautical engineer who had studied aviation broadly. Once he found the gem in the flowing river of wing theory, he brought the gem out and demonstrated how wing meets matter and functions into utility.  They did more than just tweak the side of a parachute.

Those who would choose, as he predicted, to stiffen the minimum wing would still have to nod some to him. Then for 22 years and more after his 1945 awareness (he was aware of his progress prior to filing for a patent in 1948) he diligently and gently and generously teased the world to the point where NASA's  Paul Bikle gave the orders to Charles Richard just before Christmas of 1961 to quickly and economically build some Rogallo-consulted wings that had already been wind-tunnel tested from 1958 through 1961+ at NASA. Charles Richard led his design-and-construction team and produced the series of Paresev wings, some of them being true hang gliders flown in 1962 by six top professional test pilots from as much as 13,000' in released-from-tow free-flight under a pilot-mass-shifting control to safe landing. The pilots each with their own eminent biographies and aviation accomplishments:

1. Milton Thompson
2. Bruce Peterson
3. Neil Armstrong
4. Robert Champine
5. Gus Grissom
6. Charles Hetzel

 As the project's first focus was eventual payload-carrying for assist in giving safe re-entry to space objects, payload was to be accepted; there was a kind of minimal Paresev version and then heavier payload versions that also allowed the pilots to land at higher speeds on a tricycle undercarriage. But the wing (topless---no kingpost) was of a size that could be foot-launched by a pilot in the sporting utility that Francis and Gertrude included in their patent encirclement, in later speeches, in model demonstrations, and in letters.

It is to be noted that the Rogallo wing is living behind any of the predicted stiffenings; it was the Rogallo team that found the wing and brought forth that which could be used with confidence by craftsperson far and wide in conjunction with the common bag of tricks that craftspeople were ever able to use to meet individual function and utility, such as the George Spratt triangle control frame for hang gliders, the Gottlob Espenlaub triangle-and-W control frame for hang gliders and thousands of other related already-known-aviation arts. Even John Joseph Montgomery in the late 1800s in one of his hang gliders used the triangle control fuselage part.  The form, format, construction method, tubing, Dacron, nose plates, bolts, battens, etc. were in some of the Paresev wings that were flown by the hanging pilots in 1962 from January forward.

The material expression by the Charles Richard's team--as they used the results of NASA's wind tunnel tests over various small and full-sized framed wings and stiffenings of  the Rogallo wing--gave extant art that fully precluded anyone following 1962 from validly winning global invention rights over what became a generic wing family bolstering the multi-faced burgeoning hang glider movement of the 1960s and 1970s. However, keen innovators raced to make improvements on the extant art and hundreds of inventions in hang gliding blossomed and continue to occur over the Paresev base--and beyond to distinctly different-than-the-Paresev base. 

In an effort to enrich the Rogallo a study of the Wanner patent and the seminal Rogallo patent will be undertaken; and then a step into the Barry Palmer first member of the class to be known eventually as Standard Rogallos will be made to see how that dimension fits into the context of the world that had already known flowers from the Montgomery, Lilienthal, Espenlaub, Spratt, Wanner, Rogallo, and Paresev actualities. From 1945 to 1962, the due diligence of Gertrude and Francis Rogallo will be traced into various corners of the world; and some of the post 1962 Rogallo events will be traced. We do not have the research finished, but will indicate where richer data could be found by those who want to participate in rounding out the stories. Along the way, new questions will arise; those will be worked into the presentation.  Maybe visit once a month to see what changes have been made!  Better: take on a corner of the project and send things into the project.

You:   Feel free to send notes and references to the following e-mail addresses for this project for our editors:

• Rogallo@HangGliderHistory.com

• Paresev@HangGliderHistory.com

Two versions of the patent: one raw, the other dynamically hyperlinked to respect participatory collaborative research and analysis:     Raw    and     Hyperlinked

The following is a typed version typed by editors at HangGliderHistory.com  An original copy of the patent is freely available in image form easily on the Internet. This text format makes it easy to do scholarly discussions over the patent; copy and paste and discuss, etc. via e-mail and web groups and this site.  You may print to paper an image of the original patent from at least http://www.freepatentsonline.com/2546078.pdf   Google also has a patent search and find service. http://www.google.com/patents/   

In United States patents of the utility sort, the prose takes precedence over drawings; drawings are not sufficient to capture the essence of inventions of this sort. We will undertake with interested persons a careful study of the claims and reach of the the Rogallo patent. The patent as a whole is supposed to be sufficient for those skilled in the attending related arts to build embodiments of the invention claims. So, if you are not skilled in the arts of wings, kites, aircraft, hang gliders, gliders, towed craft, etc., then your crafty embodiments will be less than those results achievable by highly skilled craftspersons when they set their mind to solve a particular utility of the patent.

Some preliminaries before the actual text of the patent:

• The patent establishes a wing that is not bound by drawings nor its degree of stiffening or shape. Then...
   

• The due diligence into Paresev and the extant common art of frames by Montgomery-Espenlaub-Spratt and others precludes post-1962 invention of the "standard Rogallo hang glider's frame format". Anyone in post-1962 was free to use such facts without royalty due to anyone except perhaps nods to the diligent forbearers of the technology. And Rogallo was by far the most diligent (for over 20 straight years and more) to get materialized NACA, and NASA facts for us all.
   

• "arcuate shape" is a correct typing of the phrase. The matter has to do with "arcs."
   

• The patent itself does not use the term "Rogallo wing" as it need not. The term's first use is hidden from this editor at the moment; some participants might take that on as a supportive project. However, the nods were so consistent from Flexikite^TM days that we have today a general nod by many people to things embodying their fundamental finding with "That is a Rogallo wing device."
   

• In slips where Gertrude should be mentioned, we apologize; together they formed a partnership that gave the world an important seminal invention.
   

• Notice the alternative for "Paresev" was "Parasev"    The mix was common in the literature. Preferred is "Paresev".
   

• Patent reading is not the easiest kind in the world. Certain customs together with the need for legal clarity brings out a kind of repetition in places that seem unnecessary.
   

• A world 20 + years later will have had the advantage of the due diligence of the inventor.
   

• Look for seeds of his invention that presage importantly with the later Barish wing and later Jalbert wing inventions. Together they found a huge wing space for hang gliding and paragliding (a subset of hang gliding).
   

• Look in the patent for disclosure that already by 1948 they had  used his invention in a model hang glider incorporation of his invention.
   

• And notice that had Gertrude or Francis stepped forward off even a 1 cm mound into the wind while flying their kite overhead, they would have had a true hang gliding experience themselves, something not required for invention. Eventually Francis did have flights in aircraft that used his wing, one being the FlightSail. Another will show in the story.
   

• Invention does not require that a person show a finished utilization, but only that the patent in the hands of one skilled in the attending arts could build a material utilization of the invention. One particular utilization of an invention does not limit the invention to that one utilization or embodiment.
   

• Part of the Rogallos due diligence surfaced in another patent United States Patent 2,751,152 filed in November 17, 1952, and granted in June 19, 1956; this second patent feature a single lobe in part of its appreciation. In this second patent they referred back to their principled seminal patent. Later NASA would formally study scores of versions of embodiments of the fundamental invention as we will illustrate in the story and discussions. Some of what NASA actually did tended to preclude Barish. But it seems that Domina  Jalbert's ram-air airfoil invention was seminal beyond Rogallos' seed of ram-air for flexible wings' sub-parts.  But such action was just part of a long list of actions that forwarded his gifting his invention to us.
   

• Further patents: [This sub-project is not complete yet.]

  • Patent number: 3296617   Filing date: Jan 23, 1963

  • In April 29, 1963, Francis M. Rogallo filed for several more related patents that got approved.  (At Google patents, just put in the patent number)

    • US Patent 3197158  Filed April 29, 1963. Issue date: Jul 1965. This patent only hints at the extension prior work done by NASA under his consultation in preparation for this patent.

    • US Pat. 3185412 - Filed Apr 29, 1963 Also filed on the same day.

    • US Pat. 3194514 - Filed Apr 29, 1963  Another filed on the same day. This divided the above patent.

  • US Patent 3446458  Filing date: Jan 17, 1964

  • Patent number: 3507464   Filing date: Mar 18, 1969

  • 
    
    
     

• Without Rogallos' wing through parawing and Paresev demonstrations  we would have Montgomery-Espenlaub-Spratt-ski-kite chopsticks, Ws, and triangles without lift, glide, minimal portable foldable hang gliders and manned kites. Instead we had a seminal wing that has evolved into embodiments that are becoming relative past history as flying wings tend not to nod to Rogallo, but to the whole of wing history and aerodynamics as the flexibility of surfaces is diminishing and high glide ratios are increasing. Eventually very low mass very rigid nanotech reliable and very strong  materials will put the flexible sails into ancient-history uses while there will still be low tote volume and ease of use with intelligent materials. However, not to be forgotten will be the generative actions of the Rogallos from 1945 through their final actions living in monuments and acclaims.
   

• Just some patents that mention Rogallo:   (To be linked...) There are many more. We aim to have a comprehensive list. Helpers on this sub-project are invited.

  • US Pat. 7007889 - Filed Jun 15, 2004

  • US Pat. 5169095 - Filed Feb 15, 1991

  • US Pat. 3353793 - Filed Jul 1, 1966

  • US Pat. 3697023 - Filed May 12, 1971

  • US Pat. 4865272 - Filed Jun 18, 1986

  • US Pat. 2439304 - Filed Feb 1, 1943

  • US Pat. 3949519 - Filed Feb 14, 1975

  • US Pat. 3237895 - Filed Mar 26, 1964

  • US Pat. 4053122 - Filing date: Jan 22, 1976

  • US Pat. 4355982 - Filed Nov 24, 1980

  • US Pat. 3995799 - Filing date: May 23, 1975

  • ETC.

  • We are want to list all  patents  from other nations that mention the Rogallo wing, please send them in.
    
    
     

• NASA later gave the Rogallos a $35,000 check in appreciation for his inputs of due diligence regarding his patent. NASA and the Rogallos gifted to the world the Paresev device formats and the deep wing studies that prefaced the 1962 flying demonstrations of towed kite and free-flight hanging-glider devices  from light and small to big and grand, from loose fully flexible parawing to inflatable to very hardened embodiments of the underlying Rogallo wing. Engineers all along the way in the NASA studies and Paresev project were consistent in recognizing that the seed of their doings was founded in the United States Patent 2,546,078.      Do not let the diagrams fool you; the invention said in the patent's prose reaches out and way beyond the momentary diagrams used just to begin an illustration of the underlying patent's invention. Diagrams of hundreds of utilizations of the patent will occur in later history. No one paid Rogallos a dime for royalties on their patent and no one needs to do so. But some of us may owe them a careful study and recognition of their contributions to flexible-winged aircraft and hang gliders.

FLEXIBLE KITE Rogallo et al. (click for all images)

United States Patent 2,546,078

Patented Mar. 20, 1951

March 20, 1951 2,546,078
G. S. ROGALLO ET AL
FLEXIBLE KITE
Filed Nov. 23, 1948
FLEXIBLE KITE
Gertrude Sugden Rogallo and Francis Melvin Rogallo, Hampton, Va.
Application November 23, 1948, Serial No. 61,702
9 Claims. (Cl. 244---153)

This invention relates to kites and more particularly to a kite having completely flexible surfaces.

It is an object of our invention to provide a kite of simple and economic construction and wherein the use of reinforcing members may be ordinarily eliminated.

It is another object of our invention to provide a kite which will be simple to fly and graceful in flight.

It is a further object of our invention to provide a kite structure which may be easily folded or rolled and requires a minimum of space in storage.

It is still another object of our invention to provide a structure for a kite having improved aerodynamic characteristics.

In general we achieve the above object by constructing a kite of a substantially quadrilateral piece of fabric, paper, or other light and flexible material, having bridle strings attached at various points, and a tail secured to the kite when necessary, so that the stress in the strings exerted at strategic points of the kite's surface maintains the kite in proper shape and configuration to be effectively supported even in a light breeze. Owing to the fact that our kite does not require the use of stiffening members, it is considerably lighter than other kites of the same area and hence more easily flown in a light breeze.

Other objects and features of our invention will evident from the detailed description which now follows taken in conjunction with the appended drawings in which:

Fig. 1 is a plan view of our novel type structure as it rests on a flat surface prior to flight;

Fig. 2 is a plan view of our kite in flight;

Fig. 3 is an elevation of our kite in flight showing an appropriate angle of attack;

Fig. 4 represents the manner in which a plurality of our kites may be coupled in flight;

Fig. 5 shows a section through 5-5 of Fig. 2;
and
Figs. 6a-c show sections of various types of reinforcements suitable for use in conjunction with our kite, if desire.

With respect to Figs. 1 through 3, our invention contemplates the use of a substantially square piece of fabric or paper 10 forming a body member having a diagonal fold line 13 provided there in dividing the body into symmetrical sections that may belly upwardly on both sides of the fold line to form lateral support surfaces when aloft. A series of bridle lines 16 through 22 are symmetrically attached to the kite and are brought together and secured to a main control line 26, as shown in Fig. 3.

The bridle lines 16, 19 and 22 are secured to the kite at the fold line 13 in any suitable manner as by punching a hole through the material just above the fold line when the kite is completely folded, and then passing strings through the holes, typing the ends thereof so as to secure the strings in their respective holes. Alternatively, adhesive patches may be utilized to hold the string ends to the kite fabric at the fold line, if desire. The bridle lines 17 and 18 are secured to the kite fabric on either side of the center line, while the lines 20 and 21 are fastened substantially at the lateral tips of the square, all of these lines being adjacent respective leading edges of the body. The particular arrangement is indicated on Fig. 1, wherein is shown exaggeratedly the string ends passing upwardly through the kite body.

The length relationships of the several lines is such as to provide any desired degree of arcuateness of the body member sections depending on the degree of wind encountered. The relationship shown is suitably proportioned for general purposes. In strong winds we have found a tail to be essential and we prefer to utilize for this purpose a ribbon-like material of any suitable type such as cloth or aluminum foil, indicated at 30. The tail 30 is attached through a swivel joint 33 to a pair of lines 35 and 38 which are secured to respective trailing edges of the kite substantially at the mid-portions thereof, as shown in Figs. 1 and 2. Alternatively, the lines 35 and 38 could be secured to the kite substantially at the locations shown for the ends of lines 20 and 21. It will be appreciated that the particular location for the attaching ends of the tail lines may be changed to suit various conditions, such as the size and weight of the kite, the weight of the tail, the wind encountered, etc. We have found, however, as a matter of actual practice, that the location shown in Figs. 1 and 2 is suitable for general purposes.

One of the pleasing aspects found in flying our kite is the fact that in gusty air or when the string is deliberately jerked the non-rigid structure allows the shape to change in a manner suggesting a flying or swimming creature. Further, in order to enhance the attractiveness of our kite, we many construct it of transparent material, such as cellophane, or cellophane reinforced with a grid of string embedded therein and provide colored pictures of birds, rockets, etc. translucently thereon. In addition, phosphorescent paint may be used so as to obtain a startling and pleasing effect when flying our kite at night.

In physical aspect, our kite performs very successfully when constructed of reinforced cellophane paper cut as a square with the sides thereof about eighteen inches long. The tail may be attached thereto by a single string terminating at the diagonal line 13 but we prefer the two-string arrangement, hereinabove described. The swivel joint 33 prevents the whipping tail from twisting the strings 35 and 38 about each other.

In Fig. 4 is shown a manner in which a plurality of kites, as hereinabove described, may be coupled for simultaneous flight. It will be appreciated that the kites need not be all of the same size, but might be of progressively smaller area, so that the bridle strings 40 would have no angular bends therein, but would represent elements and corners of an inverted pyramid from the juncture point 43 to the points of attachment with the uppermost kite. While we have shown but one form of the kite insofar as configuration is concerned, other forms are entirely feasible. For example, rectangular and elliptical configurations may be used. Further, while we prefer to utilize non-rigid non-reinforced lifting surfaces, it will be appreciated that reinforcements could be applied as shown in connection with Fig. 6a through c, depending upon the particular use the kite is to be put and upon the size thereof.

Fig. 6a represents a kite following our teaching but utilizing a reinforcement of round cross section which may be applied at the center lien 13 and also at the leading and trailing edges. Fig. 6b shows the manner of attachment of a reinforcement of flat cross section. Fig. 6c is similar to Fig. 6a except that the reinforcement is hollow and flexible so as to be filled with compressed air, or other gas, for maintaining rigidity.

Such reinforcements might conceivably be comprised of flexible material such as soft rubber tubing or adhesive tape. In any event, the reinforcing material should not be so stiff as to prevent the leading and trailing edges from assuming proper arcuate shape as the material of the kite bellies out in flight, although a rigid reinforcement could be used at the center line, if desired. In general, the use of reinforcements reduces the required number of bridle strings and considerable latitude may be exercised in the type of reinforcement used. It should be pointed out that for large kites intended for emergency use, for military or other purposes, the reinforcements may consist of hollow fabric tubes which are open at their front ends and closed at their rear ends so as to be inflatable by the oncoming wind and maintained in shape thereby. Further, the reinforcement of each edge may consist of a number of beads strung together and secured along the edge so that their mass will provide a degree of stability due to inertia, without sacrificing flexibility.

Like all kites, our kite obtains its lift from the action of wind blowing past it. The kite is maintained at an inclined attitude relative to the wind, as shown in Fig. 3, by the bridle lines and the weight of the tail. The static pressure of the air on the lower surface of the kite is increased by the airflow and that on the upper surface is - decreased, the pressure difference between upper and lower surfaces thereby providing a lift force perpendicular to the wind which supports the kite. This same pressure difference between upper and lower surfaces, in conjunction with the tension in the lines holds our kite in proper shape to efficiently utilize the air current. It is in this latter aspect that our kite distinguishes from those of the prior art, namely, the combination of a suitably flexible body and suitably proportioned bridle lines to effect a degree of arcuateness requisite to effective flight under widely varying wind conditions.

It is interesting to note the comparison between the principle of our kite and that of the conventional parachute. Both structures hold their shapes because of air pressure on a concave surface, but a parachute does not develop lift, it develops only drag, i.e. a force in the direction of the relative wind. Our structure, on the other hand, develops lift, i.e. a force perpendicular to the relative wind due to the wing-like shape in which the kite sections are maintained by the wind and the bridle lines. Further, we believe the principle described herein may be applied to man carrying devices, such as airplanes, parachutes and gliders, and in such event stabilizing and control surfaces could be added. We further believe that our principle could be utilized in the construction of a toy glider or airplane, and we have met with some experimental success by attaching a weight in place of the control string 26 and reflexing the trailing edge by means of a piece of string between the two ends of the center line. In this connection it should be noted that whatever structure or framework for supporting weights, motors, etc. might be utilized in conjunction with our device, such structure would be hung from the kite body and not secured to it in a manner which would tend to make the lifting surface rigid.

An additional phase of utility of our invention would be the construction of a kite embodying our principle but made of metal foil, either to serve as an antenna or as a radar target.

It will be appreciated that our invention is subject to many modifications without departing from the spirit thereof and we do not regard ourselves as limited to the specific illustration herein, except as set forth in the appended claims:

We claim:

1. In a device of the class described the combination of a body of flexible non-rigid material having a center line extending longitudinally thereof, and comprising wing-like sections extending transversely on either side of said center line, wherein said center line is effected by a crevice at the juncture of said sections and extends longitudinally the length of said body, and a plurality of bridle strings secured to said sections.

2. A kite comprising a body of non-rigid flexible material having a center line effected by the crevice at the juncture of symmetrical sections of said body, said sections extending outwardly and transversely to form a wing on each side of the center line, including a plurality of bridle lines secured to said sections and symmetrically disposed with respect to said center line, wherein said bridle lines are connected to each other at a common juncture and are relatively proportioned to effect transverse concavity of said wings in flight, said juncture being disposed relative said wings in flight so as to effect a glide angle therefor.

3. A kite comprising a substantially quadrilateral member of flexible non-rigid material having a center line extending diagonally thereacross, there being a leading edge and a trailing edge on each side of said center line, and a plurality of bridle lines symmetrically disposed with respect to said center line and secured to respective edges of said quadrilateral member.

4. A kite comprising a substantially quadrilateral member of flexible non-rigid material having a center line extending diagonally thereacross, and a plurality of bridle lines symmetrically disposed with respect to said center line and secured to respective edges of said quadrilateral member, including at least one bridle string secured to said quadrilateral member at said center line.

5. In a device as set forth in claim 3, including a tail member secured to said quadrilateral member and comprising a ribbon-like element having a pair of lines extending therefrom to substantially the mid-points of the trailing edges of said quadrilateral member.

6. A kite comprising a wind supportable body of flexible non-rigid material shaped as a square and having a center line extending diagonally thereacross to divide said body into symmetrical wing-like sections, each having a leading and trailing edge, including bridle lines symmetrically disposed and secured to said edges, and a plurality of bridle lines in spaced relation and secured to said body at said center line, said bridle lines having a common juncture at their lower ends whereby a pull may be simultaneously exerted on all bridle lines, the structure being such that in flight the sections are maintained in arcuate shapes substantially symmetrical with respect to the center line due to pressure of the wind acting on their surfaces in conjunction with tensile force exerted on said bridle lines.

7. A kite comprising a body member of flexible non-rigid material and having a center line effected by juncture of symmetrical sections of said body extending transversely with respect to the direction of oncoming wind, including a plurality of bridle lines secured to said symmetrical sections and to said body at said center line and having a common juncture, certain of said lines being attached to the outermost portions of said sections, whereby symmetrically arcuate sustaining surfaces are formed in said body member by oncoming wind acting against said sections in conjunction with tensile stress exerted thereon by said bridle lines.

8. In a device as set forth in claim 7, including a tail for said kite, comprising a ribbon-like material and a pair of lines secured to said body member symmetrically on opposite sides of said center line, including a swivel joint between said lines and said ribbon-like material.

9. In a device as set forth in claim 7, including reinforcements at the edges of said body member and at the center line thereof, said reinforcements being comprised of flexure during flight to a lesser degree than said body material.

GERTRUDE SUGDEN ROGALLO
FRANCIS MELVIN ROGALLO

REFERENCE CITED
The following references are of record in the file of this patent:
UNITED STATES PATENTS
Number    Name        Date
1,029,010 Guillo        June 11, 1912
1,632,822 Dahl          June 21, 1927
2,208,786 Astle         July 23, 1940
2,258,797 Overbeke   Oct. 14, 1941
2,463,135 Bach         Mar. 1, 1949

Now for collaborative analysis and unfolding of the above patent. Please send your discussion points to:  Rogallo@HangGliderHistory.com