What are dark streaks on the wings of the aircraft near the engine?

[RandomGuy88]

My question is referring to the first picture of the SR-71 on wikipedia.

http://en.wikipedia.org/wiki/Sr-71

What are those dark streaks on the wings of the aircraft near the engine?

 

[Antiphon]

That's jet fuel leaking out of the seams. The SR-71 was designed to "seal up" at full speed through thermal expansion at Mach 3+. It has no fuel tanks in those sections of the wings. The fuel is stored directly in the bulkhead to save weight.

 

[Cyrus]

Keen observation!

 

[Phrak]

That's jet fuel leaking out of the seams. The SR-71 was designed to "seal up" at full speed through thermal expansion at Mach 3+. It has no fuel tanks in those sections of the wings. The fuel is stored directly in the bulkhead to save weight.

You sparked my interest. I know the fuel is rather thick. It turns out to be JP-7. But check out this Wikipedia quote: "SR-71 development began using a coal slurry powerplant,"! I never would have guessed that one.

 

[alphy]

The dark streaks on the wings of the aircraft near the engine are most likely caused by the high temperatures and pressures experienced during supersonic flight. As air flows over the wings, it becomes compressed and heated, which can lead to the formation of shock waves. These shock waves can cause localized areas of high heat and pressure on the surface of the wings, which can result in discoloration and streaking. This phenomenon is commonly seen on high-speed aircraft and is a normal occurrence. Additionally, the high speeds and temperatures can also cause small particles, such as soot or debris, to adhere to the surface of the wings, further contributing to the dark streaks. In summary, the dark streaks on the wings of the SR-71 are a result of the extreme conditions it experiences during supersonic flight and are not a cause for concern.