head resistance
head drag

They produced a tremendous amount of head resistance at their present velocity, for already the needle of the radio speedometer had moved over to one mile a second.

The trilobe envelope allowed the gondola to be hung closer to the envelope, reducing the overall height of the aircraft and slightly reducing head resistance.

When he asks about a pair of pants, he will learn about moisture vapour transfer rate and hydrostatic head resistance, and wickability.

Then there's Drift, my horizontal component, sometimes, though rather erroneously, called Head Resistance; he's a villain of the deepest dye, and must be overcome before flight can be secured."

The primary requirement of a cooling radiator is that it shall dissipate heat; and for cooliug the engines of aircraft it is essential that the head resistance shalI be low.

It is possible that the rate of heat transfer for the whole radiator may be increased, while added air resistance of the core may actually reduce the head resistance of the fuselage and radiator.

She had an impervious outer cover, a simplified cruciform tail, and with a head resistance of just 40% by comparison her shape was more streamlined than the contemporary Zeppelins, as well as the No. 9, 23 or 23X class which were to follow.

But both heat transfer and head resistance are greatly affected not only by the speed of air past the cooling surfaces, but by the character of the flow-whether the air passes through the radiator in smooth streams, or with eddies and vortices.

Any form of construction that imparts additional turbulence to the air may be expected to increase the resistance to flow of air and consequently to decrease the flow through the radiator for a given flying speed, while at the same time increasing the head resistance.

On the other hand, if the radiator is to be used in such a position as the nose of the fuselage, the airflow through it at best is low, and an increase in airflow is accompanied by an increase in head resistance of the combination of fuselage and radiator.