How not to scale flows the cautionary tale of Howard 1|14 When - PowerPoint PPT Presentation

How not to scale flows ∼ the cautionary tale of Howard ∼ 1|14

When was the second largest aircraft in history built? 1947 2|14

H-4 Spruce Goose, 1947 Photo from FAA (public domain) 3|14

H-4 Spruce Goose, 1947 Photo from San Diego A&S Museum (public domain) 4|14

Figure by Clem Tillier (CC-by-sa) 5|14

Figure by Clem Tillier (CC-by-sa) 6|14

The Hughes H-4 Spruce Goose fl ew just once and never exceeded 20 m altitude... . . . because Hughes didn’t study this chapter. 7|14

CC-0 Olivier Cleynen 8|14

Reference A and new machine B If C F D B = C F D A : 휌 B F D B = ( V 2 A ) F D A S B 휌 A B V 2 S A 휌 A = ( 1 F D A ) V B 휌 B S A F D B 2 V A S B 9|14

Reference A and new machine B If C F D B = C F D A : 휌 A = ( 1 F D A ) 2 V B 휌 B S A F D B V A S B 휌 A 휌 A = ( = ( 1 1 L 2 L 3 A ) L A ) 휌 B 2 휌 B L B 2 A B L 2 L 3 B ∼ ( 1 L A ) V B L B 2 V A 10|14

CC-0 Olivier Cleynen 11|14

what about power? Reference A and new machine B If C P B = C P A : 휌 B ̇ ̇ W B = ( V 3 A ) 휌 A S B B W A V 3 S A ̇ ∼ L 2 3 ̇ 2 W B L B B 3 L 2 W A 2 L A A 12|14

CC-0 Olivier Cleynen 13|14

H-4 Spruce Goose, 1947 Photo from FAA (public domain) 14|14