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Technology Spotlight: Follow along each day as NAA technology expert Al Robbins posts and comments on one of the >4000 United States patents related to lighter-than-air (LTA).
  • 19 Nov 2013 9:00 AM | Deleted user

    Todays patent is Ellsworth’s only airship patent.

    His other patent, P/N 331,288, claimed a similar cam-controlled

    feathering blade system for windmills.

       A further object of the invention is to provide an air-ship 

    embodying an aeroplane having a gas bag or receiver secured 

    thereto and provided with side propellers for elevating and 

    directing the course of the vessel.

           A further object is to provide means for varying the angle

    or inclination of the feathering propeller blades so as to change

    the thrust of said blades and thereby cause the latter to pull in 

    any desired direction.”

    NOTE: There is no indication of any propulsive or aerodynamic

    control surfaces, other than the two adjustable paddle-wheels. 

    No means of controlling the Angle of Attack.

    Google’s patent site doesn’t list either of the classifications 

    assigned by the USPTO.  Instead it lists an  international 

    "Cooperative Classification"  (a new system introduced in 

    January 2013) code B64G39/005. B64G series applies to 

    Cosmonautics, not Airships (B64B), Aircraft (B64C) or 

    B64D (Equipment for fitting in or to  aircraft).

    Ellsworth claimed a hybrid winged-airship propelled and controlled 

    by side-mounted individually adjustable “propellers” or 

    paddlewheels. His patent doesn’t indicate how much of the vehicle’s 

    gross weight is supported by buoyancy, by the wings, or by dynamic 

    lift from the paddlewheels.

    The patent office might have also assigned:

      244/5 (Airplane, weight diminished by buoyant gas),

      244/25 (Airship with sustaining wings),

      244/27 (Airship and paddle wheel sustained), and/or

      244/96 (Airship control).

    This patent has not been cited by any modern patents.

  • 18 Nov 2013 9:41 AM | Deleted user

    Todays patent is Kothmann’s only LTA patent.

    Kothman describes his invention as follows:

        The airship is simple to assemble from a minimum of six 

    pre-manufactured assemblies including the lifting gas source. 

    These are:

       1) the fabric hull 16,

       2) the lifting gas bag 1,

       3) the air diaphragm bag 6,

       4) the radial triangular frames 5 and

       5) the rigid frame assembly comprised of the crew compartment 4,

           the equipment deck 17, the radial truss 11, the propulsion 

            tube 22 and the deck 2.

    The rigid frame assembly also includes the propulsion unit and 

    all other equipment such as the generator, fuel tanks, pumps, fans 

    and controls. The invention can be field assembled anywhere or 

    disassembled and transported to remote locations.”

          “In the preferred embodiment, the compression ring will be 80 

    feet in diameter and the airship will be 40 feet in overall height, 

    although the ship need not be limited to these dimensions. The 

    size and simplicity of the airship make it ideal for a personal 

    pleasure craft or recreational vehicle. The craft's controls and motion 

    through air is more like a submarine in water than other airborne 

    vehicles. Persons with minimal training and basic navigation skills 

    can safely operate the airship.”

    NOTE:   Kothman introduces a unique high-pressure, essentially 

    lens-shaped airship: Normal pressure 1.5 atmospheres; Compressed

    lifting gas stored at up to 200 PSI (pounds per square inch). The 

    envelope pressure represents a major leap, but the rate, and 

    possible change of buoyancy due to compression appear to be

    reasonably within the current state of the art. Vehicle dynamics

    are virtually ignored.

    This patent should be required reading for anyone interested in
    future airship designs. It cites 18 patents and is already cited
    by 20 U S patents, one disclosure, and three foreign patents.

    The USPTO only assigned two classifications: 244/30 (Airship) 

    and 244/97 (Buoyancy varying). The seven approved claims cover, 

    inter alia:

         244/87 (Rudders and empennage),

         244/94 (Ballast storage and release),

         244/96 (Airship control),

         244/98 (Gas bag inflation),

         244/100R (Landing gear),

         244/115 (Mooring devices),

         244/125 (Airship hull construction),

         244/126 (Airship skin construction),

         244/128 (Airship gas cell construction and arrangements) and

         244/130 (Aerodynamic resistance reducing).

    N.B. Kothman does not power his airship with his LTA gas, 

    although he discusses hydrogen as the lifting gas.

  • 17 Nov 2013 7:51 AM | Deleted user

    Todays Mooring Mast patent was Dill’s only U.S. Patent.

        This invention relates to mooring masts for airships, the object

    in view being to provide practical, safe and convenient operable

    means for anchoring or mooring an airship, particularly of the

    lighter than air type, to a mast, the construction embodying means

    whereby the usual rolling and pitching movements of the craft are

    provided for, the mooring mechanism counterbalanced. and the

    mast as a whole being adapted for easy assembly, erection and


    NOTE: The patent describes a single-point nose-mooring device. 

    Although Dill’s Figures illustrate a wire-braced stick mast,

    none of the approved claims discuss the mast itself, or any method

    of erecting or bracing it. 

    The patent neither describes nor claims any mechanism for preventing 

    the airship from pitching and/or rolling.

    This patent is cited by one modern patent:

     P/N 5,497,962 Mooring tower assembly for a lighter-than-air 


  • 16 Nov 2013 6:03 AM | Deleted user

    Todays patent is Webber’s only patent related to aviation.

       “A further object of the invention is to provide an airship which

    combines a gas bag and supporting planes in such a manner as

    to obtain greater buoyancy, which has the propellers mounted in

    such a manner that they can be quickly swung into various

    angular positions so as to either lift the machine straight  up or 

    drive it forward or backward, which can be quickly turned to the 

    right or to the left by means of the propellers, and which can be 

    guided in the usual manner by means of a rudder.”

    NOTE: The text of a patent may disclose several features which 

    are not included in its claims. Since we don’t have access to the 

    original application (or any of the correspondence between the 

    inventor and the patent office), there is no way of telling why, 

    or how many of Webber’s claims were disallowed.


    None of the approved claims even mention the ship’s car (which

    Webber refers to as a boat) or it’s air-filled floatation devices.

    The USPTO neglected to cite 244/56 (Tilting propulsion)

    although the twin shrouded propellers are a key component

    of five of the six approved claims, and according to the text

    also used to propel and steer the airship while it is waterborne.

    This patent is cited by only one modern patent:

       4,238,095 Method of and apparatus for anchoring airships

                     and propulsion means for airships.

  • 15 Nov 2013 12:44 PM | Deleted user

    Todays patent was Campau’s only invention related to LTA.

          A particular object of the invention is the provision of a 

    dirigible balloon, the movements of which may be readily 

    controlled without loss of any of the gas contents thereof.

          Another particular object of the invention is to provide a 

    dirigible balloon having improved apparatus for handling the 

    supply of gas in the balloon.

          One form of the invention is embodied in a dirigible balloon 

    having a plurality of gas compartments communicating with 

    bellows adapted to receive excess gas from the compartments,

    the bellows being connected to a gas compressor adapted to 

    withdraw excess gas therefrom. The balloon is preferably 

    provided with a tubular frame in which the excess gas may be

    stored, the gas being withdrawn from the bellows by the 

    compressor and then pumped into the frame. 

    Means is provided whereby the gas may be returned to the 

    bellows and thence to the gas compartments.”

    NOTE: Campau titled his patent “Dirigible balloon”.  None of the 

    claims mention the type, shape, or structure of the machine. 

    The six claims refer to “A device of the (kind class - character) described,….”. 

    Only Claim 3 even mentions a structure.

    All claims involve a system consisting of (undefined) bellows,

    Compressor(s), and one or more gas compartments – 

    presumably controlling the distribution of a Lighter-than-Air gas.

    The USPTO should have cited 244/128 (Airship gas cell construction 

    and arrangement) and 244/88 (Gas bag inflation) rather than

    244/125 (Airship hull construction).

    This patent is cited by:

     2,450,954  Means for indicating the state of gas in cells of aircraft,

     4,773,617  Lighter-than-air craft,

     5,026,003  Lighter-than-air aircraft,

     5,110,070  Rigid airship having ribs and long beams forming a 

                       carrier frame,

     5,251,850  Device for adjustment of the height of an airship,

     6,311,925  Airship and method for transporting cargo,

     8,091,826  Aerostatic buoyancy control system, and

     WO 1990009312  Device for adjustment of the height of an airship.

  • 14 Nov 2013 4:37 AM | Deleted user

    Todays patent is the last of Krell’s twelve U.S. patents.

          The auxiliary equipment for airships moored on masts is still 

    far from perfect, whether a high or low mast, separately mounted

    or a mast mounted above the inlet opening of a rotary hangar is 


          It is above all necessary to maintain the airship tied up at or 

    anchored to the mast in a steady horizontal position without 

    preventing it from giving way in the horizontal direction or from 

    swinging around the mast.”

    NOTE:  This is the last of Krell's series of patents designed to keep 

    a moored airship pointed into the wind while minimizing pitching 


    All nine claims begin: “In auxiliary equipment for airships moored 

    to masts,This patent is cited only by P/N 2,954,614 "Flight training 

    apparatus for hovering type aircraft".

    The USPTO capriciously assigned a secondary classification from

    Class 23 (CHEMISTRY: PHYSICAL PROCESSES), rather than:

      244/97 (Buoyancy varying), and/or

      244/127 (Airship load attachment).

  • 13 Nov 2013 5:34 AM | Deleted user

    Todays patent is one of Kraft’s 70-plus U.S. patents.

    One of a handful devoted to airships or balloons.

        My invention relates to a keel structure for semi-rigid airships, and

    it has particular relation to the construction and arrangement of the

    individual struts, and to means for securing said struts into the desired

    relationship to form an airship keel.

         One object of my invention consists in forming a novel type of strut,

    column or girder, which is of relatively light weight, which is simple and

    inexpensive to make, and which is particularly adapted to withstand

    great tensile and compressive stresses.

          Another object of my invention conslsts in providing a novel type of

    end fitting whereby the columns or struts which constitute the fabricated

    structure of the keel are held in the desired relationship.

          A still further object of my invention consists in forming a novel

    arrangement of columns or girders and their fittings to form a keel

    whereby great resistance to the deformation of the keel from any forces

    whatsoever is obtained with a minimum of weight.”

    NOTE: Most of Kraft’s patents were devoted to rubber products.

    It is surprising that such an experienced researcher, would have

    limited his novel, light-weight component to a semi-rigid 

    airship application.

    This patent is cited by five modern patents, none involving aircraft:

      2,519,230  Mast and spar of yachts and other craft,

      2,738,039  Masts, towers or like structure,

      2,912,075  Support structure constructed from hollow members, 

                        more particularly tubes of thin hard-rolled metal sheets,

     4,027,449   System for constructing spatial structures, and

     4,494,351   Booms for cranes or the like.  

  • 12 Nov 2013 6:24 AM | Deleted user

    Todays patent is the last of Stahl’s eighteen U.S. patents 

    to be issued; the application was filed fifteen years earlier.

           “In airships, which are mostly provided with single gas-cells, 

    similar, but still more complicated conditions prevail. On the one 

    hand, by means of the steering device, a certain dynamic upward 

    or downward motion can be produced, whereas, on the other hand,

    losses of gas and ballast should, as far as possible, be avoided. For 

    this reason, it is of great importance for the pilot to be constantly 

    informed with regard to the fullness condition of the gas-cells. This 

    can be effected in such a manner that, for recording the fullness 

    condition of airship cells, the wall of the cell is connected with a 

    device which whenever the wall of the cell becomes slack or the 

    volume of the cell exceeds a certain limit, operates an electric signal. 

    An electric signal is of special advantage, as it will respond safely in 

    the case of certain variations of form.

          In the further development of the invention the device is 

    connected with a pointer and scales, so as to insure a permanent 

    control of the fullness condition, without having recourse to a 

    number of contacts.”

    NOTE: Slightly misleading title. Separate claims cover devices to 

    remotely monitor gas cell(s) volume (or pressure) on either rigid 

    or non-rigid air ships.

    (Normally for semi-rigid and non-rigid airships, the total envelope 

    volume would be assumed to remain constant and the ballonet fullness


    This patent has been cited by two modern U.S. patents:

      3546944  Fluid pressure indicator,

      7500637  Airship with lifting gas cell system,

         and one German patent

      4416306  Motor driven air balloon system.


  • 11 Nov 2013 7:02 AM | Deleted user

    Today is Veterans Day. A day for all veterans to

    remember and give thanks to our Merchant Marines.

    We'd never have won WW I or WW II without them.

    Todays patent is the last of Myers five patents related to 

    balloons and airships.

    Myers was the first American to identify himself as an 

    Aeronautical Engineer and one of the first to build

    and fly a steerable balloon. 

       “The invention contemplates the use of an explosion engine for 

    propelling the airship, and one object is to provide an arrangement

    whereby the exhaust gases from the engine may pass into the gas 

    bag to affect the buoyancy or equilibrium thereof.

         A further object of the invention is to provide improved steering

    devices for the airship.

          A further object of the invention is to provide improved means

    for insuring that the gas bag will maintain its normal shape at its 

    ends under heavy wind pressures.

          A further object of the invention is to provide an arrangement 

    whereby thegas contained in the gas bag may be used as a fuel.”

    NOTE: Figure 2, on the second sheet, illustrates the method of 

    pressurizing the fore and aft ballonets, and also how the lifting gas 

    is supplied to the motor, which Myers powers either with the gas 

    or a liquid fuel. Myers adjusts buoyancy by venting, or consuming, 

    the LTA gas AND by using the engine exhaust gas to heat the air 

    and lifting gas in the envelope.

    The USPTO did cite three appropriate classifications, but failed to 

    cite several others:

    244/61 (Power plant using airship gas as fuel),

    244/87 (Rudders & empennage),

    244/128 (Airship gas cell construction and arrangement).

    The patent doesn’t discuss how the car (which contains the engine,  

    all propulsion and control equipment and the crew) is connected to 

    the gas bag. Nor does it include any provisions for landing or mooring 

    the airship. None of the figures show any connections to the high 

    pressure sections at the bow and stern of the envelope.

    This patent is cited by three modern patents:

       3,897,032  Method for operating airships, particularly by 

                          means of hydrocarbon gas or hydrogen,

       4,042,192  Balloon with deflation and maneuvering ports, and

       4,090,682  Pressure and hot air relief vents for a pressurized hot

                         air airship.

  • 10 Nov 2013 1:57 PM | Deleted user

    Todays patent was Lueck’s only U.S. patent.   

          “The object of this invention is to provide a dirigible air-ship 

    specially adapted for use in war. For this purpose the machine is

    provided with an observation-platform located above the gas-bags, 

    and with a magazine for ammunition, bombs, etc., at the lower 

    part of the machine.”

    NOTE: The USPTO assigned only one aeronautical classification. 

    It ignored construction classifications (244/125, 244/126 and 244/127), 

    and 244/25 (Airship with sustaining wings), 244/87 (Rudders and 

    empennage), 244/100R (Landing gear); all of which were included

    In the patents claims.

    The text and the claims relate to lens-shaped lifting bags, with multiple

    wings and rudders; all supported by triple pontoons for water landings.

    The patent doesn’t claim that such a ship might be capable of vertical 

    flight, even with a minimum crew, fuel, oil or other supplies and no

    ordnance aboard. 

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