During the development of the Supermarine Spitfire, a version was built with entirely flush head rivets (Prototype K5054). This took a long time, and was more expensive, but increased the speed of the Spitfire.
Naturally, the government wanted them built faster and cheaper. In order to do that, Supermarine needed to find out how many of those flush head rivets could be replaced with normal dome head rivets. So every rivet head was covered in glue and a split pea. Then there was a test flight.
It was 22mph slower.
Over the next few flights they slowly removed the split peas and eventually found where they could use normal rivets and not affect the speed of the Spitfire.
Another plane fact... (I'm a geek...)
At normal operating altitude, the air around Concorde was around -60°C
But as it was moving at around Mach 2.04 (~1560mph) the skin temperature was around 125°C
This temperature differential caused Concorde in flight to expand. By around a foot. This was by design. Expansion areas were included in the airframe. The main one was inbetween the flight engineers console and the bulkhead. That's why a few of grounded Concordes have the Captains hat wedged in there. Placed in there during the final flight and then left.
Another area that shows the expansion was in the floor. Under the carpet there are sliding panels. If you could see sky, you should tell someone.
Naturally, the government wanted them built faster and cheaper. In order to do that, Supermarine needed to find out how many of those flush head rivets could be replaced with normal dome head rivets. So every rivet head was covered in glue and a split pea. Then there was a test flight.
It was 22mph slower.
Over the next few flights they slowly removed the split peas and eventually found where they could use normal rivets and not affect the speed of the Spitfire.
Another plane fact... (I'm a geek...)
At normal operating altitude, the air around Concorde was around -60°C
But as it was moving at around Mach 2.04 (~1560mph) the skin temperature was around 125°C
This temperature differential caused Concorde in flight to expand. By around a foot. This was by design. Expansion areas were included in the airframe. The main one was inbetween the flight engineers console and the bulkhead. That's why a few of grounded Concordes have the Captains hat wedged in there. Placed in there during the final flight and then left.
Another area that shows the expansion was in the floor. Under the carpet there are sliding panels. If you could see sky, you should tell someone.
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