A wing and a prayer

One of our planes was missing, two hours overdue
One of our planes was missing, with all its gallant crew
The radio sets were humming, we waited for a word
Then a noise broke through the humming - and this is what we heard:

Comin' in on a wing and a prayer, Comin' in on a wing and a prayer
Though there's one motor gone, we can still carry on - Comin' in on a wing and a prayer 

This week we have been looking at math in popular phrases (hammer and nail, mortar and pestle, wing and prayer). Math is everywhere in our culture, not just inside the Excel Math curriculum we create here at Ansmar Publishers. Today my mind is fixed on an expression attributed to songwriters Harold Adamson and Jimmie McHugh in 1943:

A wing and a prayer has come to mean "we are barely able; we may not succeed; but we are trying our best and praying we will make it"

Otto Lilienthal gliding with a wing, circa 1895

Researching the term WING today, I found much more than I expected. Some of the data appears below. Your challenge is to select the numbered item that defines our phrase:

wing(s)

1. noun: modified forelimb of a bird, covered with large feathers and usually specialized for flight
2. noun: insect's organs of flight, including a vein-covered membrane growing out from the thorax
3. noun: organ of flight in certain other animals, such as the forelimb of a bat
4. noun: aircraft's main lift-generating surface OR an aircraft designed as one complete wing
5. noun: position in a flight formation, just to the rear and to one side of another aircraft
6. noun: organ or apparatus resembling a wing OR the wings of a sphenoid bone
7. noun: resembling a wing in form, function, or position; such as a sail of a windmill or a ship
8. architecture: part of a building that is subordinate to the main part
9. automotive: (British) the part of a car body that surrounds the wheels (US term is fender)
10. automotive: inverted airfoil on a race car that produces downforce at high speed
11. botanical: lateral petals of a sweet pea flower OR outgrowths on wind-dispersed fruit or seeds
12. business: an affiliate or subsidiary of a parent organization
13. clothing: insignia worn by a qualified aircraft pilot
14. farming: outside angle of the cutting edge on a plough
15. furniture: pieces that project forward from the sides of the back of a chair
16. military: tactical formation in the air forces, consisting of two or more squadrons
17. nautical: projection on the side of a ship's hull OR a jetty or dam for narrowing a channel of water
18. politics: faction or group within a political party; as in left wing or right wing
19. sports: either side of a soccer pitch near the touchline OR a player assigned there
20. theatre: space offstage to the right or left of the acting area in a theatre
21. buffalo wings: fried chicken wings with hot sauce, dipped in dressing; developed in Buffalo, NY
22. clip your wings: to restrict your freedom OR thwart your ambition
23. fear gave wings to his feet: cause of rapid motion to escape danger
24. in the wings: ready to step in when needed 
25. on a wing and a prayer: with only the slightest hope of succeeding
26. on Eagle's wings: in several Bible passages OR popular devotional song for memorial services
27. on the wing: flying OR travelling OR about to leave
28. spread or stretch your wings: to make full use of your abilities
29. take wing: to lift off or fly away OR to depart in haste
30. under your wing: in your care or tutelage
31. wing it: to make things up or ad lib
32. wing window: the US name for a quarterlight or vent window on a car
33. verb: to make your way swiftly as if on wings OR to cause to move as if on wings
34. verb: to shoot or wound a person superficially, as in the arm
35. verb: to provide with wings

What does this phrase have to do with math? Everything! I'm sure you know (perhaps from personal experience) that many students approach math tests with a wing and a prayer.

I won't try to define prayer today. We'll end with a flying wing developed by Dan Dougherty, at Cal State University in Long Beach. Dan proved he was good at math, and while still a student was hired as a designer for Northrup Grumman.