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P/N 1,651,755 December 6, 1927

06 Dec 2013 11:57 PM | Deleted user

Todays patent is one of Dürr’s many U.S. patents assigned to Luftschiffbau Zeppelin.

My data base includes 31 U.S. patents issued to  Dr. Dürr 

(Dürr. Durr, or Duerr). Most were assigned to Luftschiffbau Zeppelin.

You can only search for these older patents (pre 1970’s) by 

Patent Number or currently assigned classification(s) ) on the USPTO 


You can find nearly half of them on Google.com/patents under:

  Inventor (Dürr, Durr, or Duerr),

  Exact Phrase (Ludwig Dürr) , or

  Assignee Name (Zeppelin and Luftschiffbau Zeppelin). 

Perhaps some of our members might be able to tell us how many German patents he held.

       Because of the ship having cars situated underneath its 

hull or body the lower rudder will have less efficiency than 

the upper one, both having the same surface and usually the

same shape. This causes a very undesirable effect on the ships

horizontal course, as the resistance from the rudder above the

hull or body will differ from the resistance of the lower rudder, 

and this will have a rolling effect on the ship as a whole.

     According to my invention I am doing away with these 

drawbacks by horizontally extending the surface of the lower 

rudder, so that it is wider than the upper one. Furthermore it 

may be advisable to also increase the area of the lower rudder 

by an adequate change in its shape. Also in accordance with

my invention it may be useful to provide means for always

giving the lower rudder a wider angle of deviation than the

upper rudder has at the same time. This for example may be

attained by making the operating levers of the lower rudder

shorter than those of the upper rudder while the control wires

of both rudders are moved over equal distances.”

NOTE: As chief engineer for Zeppelin throughout the Rigid Airship 

era, Dr. Durr was responsible for the design and production of the

vast majority of all the world's rigid airships.

The USPTO neglected to cite the primary classification -
244/87 (Rudders and empennage). It might also have cited 

244/125 (Airship hull construction).

Consequently, it ignored the purpose of the invention, to reduce 

unintended rolling force and unwanted torque on the tail surfaces 

of his huge rigid airships during turns and when operating in 

cross winds. N.B. The patent addresses only two methods of

correcting the problem: Increasing the size of the lower rudder,

and/or increasing the angular displacement of the lower rudder

compared to that of the upper rudder.

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