The Polar Airship 



215 



that blow over the Arctic Ocean in July 

 or August. 



And what are we to do when stronger 

 winds blow? That is another story. 



PROTECTION DURING STORMS 



With unfavorable winds of higher ve- 

 locities we shall stop the motors and 

 throw out upon the ice-sheet over which 

 we are sailing a dragging anchor or re- 

 tardateur — a device calculated to offer 

 the maximum of resistance in proportion 

 to its weight — and by this means to drift 

 slowly with the adverse wind. 



Assuming that this method works out 

 as well in practice as in theory — and 

 there are many reasons for believing that 

 it will do so to at least a fair degree — we 

 have then this principle: 



1. All the winds that blow with our 

 course, directly or obliquely, add their 

 movement to the advance which we ex- 

 pect to make with our motors and help 

 us so much on our way. 



2. But contrary winds of velocities 

 greater than our motor speed, or so great 

 that motoring against them would be an 

 uneconomical use of fuel, are not losses to 

 be deducted at full value from the pro- 

 gress of the airship, because the influence 

 of such winds is largely neutralized by 

 the action of the dragging anchor or re- 

 ;ardateur. 



In other words, all of the value of 

 favorable winds is placed on the credit 

 side of our ledger or log, while only a 

 part of the value of the unfavorable 

 winds has to be written down on the 

 debit side. 



And the significance of this, in the last 

 analysis, is that it will require a most ex- 

 traordinary combination of circumstances 

 to prevent us getting more help than 

 hindrance from the winds. 



Before I went to Paris to make a com- 

 plete study of the problem from the 

 standpoint of practical aeronautics, it was 

 a part of the plan to motor in favorable 

 winds or adverse but light winds, and in 

 case of winds both adverse and of rela- 

 tively high velocity to anchor firmly to 

 the ice by means of grappling irons and 



steel cables. Eminent aeronautic engi- 

 neers had said this could be done with 

 safety. They pointed to the fact that the 

 Lebaudy ship had been several times thus 

 firmly anchored to the earth, riding out 

 rather severe squalls. 



But this method was condemned by a 

 majority of the practical men who were 

 consulted. Their objection was usually 

 expressed in language like this: 



"Yes, you can undoubtedly make firm 

 and safe anchorage in winds of 10, 15, 20 

 perhaps 25 miles per hour. You can cal- 

 culate the resistance which your ship will 

 offer to such winds, and put the necessary 

 strength into your anchors, cables, sus- 

 pensions, and envelope. But supposing 

 that while you are anchored with devices 

 made to stand, say, 25 miles per hour the 

 wind should suddenly freshen to 35 or 

 45 miles per hour. That would produce 

 a vast increase of the stress upon all your 

 tackle, for the augmentation of pull would 

 be, not simply in proportion to the speed 

 of the wind, but as the square of the 

 added velocity. Your tackle might break, 

 or the form of your balloon might be col- 

 lapsed by the pressure. If the balloon 

 were to lose the rigidity and symmetry of 

 its form the wind would exert still 

 greater force upon its flattened surface; 

 and that might spell disaster." 



Others urged that were a gale of wind 

 to attack the anchored ship the enormous 

 pressure would force the balloon down 

 toward the ice, and might even thrust it, 

 or its suspended car, upon the surface of 

 the ice-sheet with such violence as to 

 wreck the whole affair. They pointed 

 out that the effect of the wind upon the 

 airship in such case would be something 

 like that shown diagrammatically in 

 Figure 1. 



In a calm the anchored dirigible would 

 stand as at A. In a wind of 25 miles per 

 hour, for example, it would be forced to 

 a position as at B. With a wind of 35 

 miles per hour or upward it would be 

 thrust down to C. 



They admitted, it is true, that with 

 compensating weights — such as heavy 

 guide-rope equilebreurs, suspended below 

 the ship, and so disposed that they could 



