Why does the Beech Staggerwing have its low wing in ahead of the high wing? What are the aerodynamic ideas behind this? Other biplanes of the era had the opposite, low wing behind the high one.
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asked Mar 25, 2014 at 5:47
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$\begingroup$ looking at the picture (didn't knew the plane before) my impression is that it was a structural/ease-of-use choice and not an aerodynamic one $\endgroup$– FedericoMar 25, 2014 at 7:40
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6$\begingroup$ it lets you step in behind the wing instead of in front of the wing right next to the propeller $\endgroup$– ratchet freakMar 25, 2014 at 8:45
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3 Answers
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Notice the retractable landing gear? With a tail-wheel design, the main gear work best at or ahead of the center of gravity. The Staggerwing has a neat and efficient retractable main gear, that folds onto the lower wing. But the lower wing has to be farther forward than usual for this to work.
The two wings on a biplane interfere with each other, but the biplane structure is very strong and stiff for its weight. So the Staggerwing's design gives up some wing efficiency for strength and light weight. Then it gives-up a little more for the reverse stagger that puts the downwash of the lower wing right under what should be the high pressure under the upper wing.
However, the design gets good speed from the retractable gear reducing drag. And both wings, upper and lower, join the fuselage at 90 degrees, with no struts or other sources of drag. Aerodynamically, a very clean design. the Beech Bonanza looked more modern, but the Staggerwing had the same cruising speed, 176 knots, 202 mph. It also had a 450 hp P&W Wasp Junior, while the Bonanza got along with a 300 hp Continental.
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2$\begingroup$ wow, the performance comparison is really interesting! $\endgroup$ Mar 31, 2014 at 14:31
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$\begingroup$ Bill IV, the Staggerwing has both a strut between the upper and lower wings, and wire bracing between the wings. See Google Images for photos that show this clearly. $\endgroup$ Mar 31, 2014 at 15:41
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1$\begingroup$ Skip Miller, sorry, I wrote confusingly. The Staggerwing does have a single strut joining the wings out by the tip, and paired bracing wires in a double "X" between those struts and the sides of the fuselage. (See red plane at the top of this page) But the wings themselves join the fuselage cleanly, no struts in the airflow connect either wing to the fuselage. Compare to a Stearman, SPAD or Tiger Moth. The Bristol SB2 has struts from both lower and upper wing to the fuselage. By contrast, the Fokker DR-1's low and mid wings have no struts to the fuselage, Only the top wing needed them. $\endgroup$– Bill IVApr 9, 2014 at 2:34
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$\begingroup$ @BillIV: The aerodynamic efficiency is not really affected by staggering the wings. The Staggerwing arrangement is not inferior to one with positive stagger. $\endgroup$ Dec 1, 2014 at 19:11
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$\begingroup$ I'll get references, or lack of them, and get back to you. $\endgroup$– Bill IVJan 5, 2015 at 3:11
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Wikipedia (certainly not a proper source) suggests:
The Model 17's unusual negative stagger wing configuration (the upper wing staggered behind the lower) and unique shape maximized pilot visibility while negligibly reducing interference between the wings.
which itself is sourced from "The Beechcraft Biplanes". Sport Avaition. January 1961.
Normally as you state the choice is for the lower wing to be further back due to the negative pressure on top which you do not want interfering and reducing the effectiveness of the upper wing.
answered Mar 25, 2014 at 11:10
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Ted Wells did this just for visibility. It turned out that is was also good for flight characteristics as the bottom wing would stall first causing the airplane to pitch forward thus preventing the top wing from stalling. It also provided the ability to retract the gear into the wing.
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$\begingroup$ You should provide links and references for sources and further readings. $\endgroup$– Manu HMar 5, 2018 at 6:33
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1$\begingroup$ Addendum to @ManuH 's comment: promoting a book on amazon is not really ok. $\endgroup$– FedericoMar 5, 2018 at 8:13
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$\begingroup$ @Federico I agree. Citing a book without an amazon link should make the job. $\endgroup$– Manu HMar 5, 2018 at 9:56