Aircraft Weight: How Much Difference Could a P-51 Mustang Rivet Make?
A Flight of P-51 Mustangs
Aircraft weight - why does it matter?
Some people spend a lot of time getting aircraft weight and balance just right. Of course first of all you don't want your plane to fall out of the sky, but if you're loading a lot of military equipment on a plane and the aircraft weight is even a little off balance, it can matter to fuel costs and maneuverability.
Well, this story is not exactly about aircraft balance, but it is about aircraft weight, specifically P-51 Mustang weight, and it is dedicated to those unappreciated people who figure out aircraft weight, to all the engineers who spend a lot of time thinking about things that seem too small to matter, and especially to Mary Feik.
Fuel is a lot of aircraft weight
There is a poem about a kingdom being lost because a horseshoe nail was missing. This story is the same idea, the other way around. This is about a war being won because of a different kind of aircraft rivet.
How far can an airplane fly? It depends a lot on how heavy it is and how much fuel it can carry. A very heavy plane will need a lot of power, and to run powerful engines for a long time, it takes a lot of fuel. To carry a lot of fuel, it will need a lot of space, and carrying a lot of volume of fuel makes it that much heavier.
In World War II, bombers had enough space for the fuel to get to Germany from England and get back. But the Germans didn't exactly want bombers over Germany, and shot at them! With airplanes, you don't bring along someone bigger to protect you, you bring along someone faster. That was the P-51 Mustang. But there was a slight problem; being smaller, the P-51s didn't have as much fuel space and couldn't get all the way to Germany. So that was almost no help at all to the bombers; they didn't need protection in England!
Details of air power
It's hard to remember today how short the reach of air power was in WWII. At the beginning of the war, stripped-down aircraft could be flown from the US to Britain, but only toward the end of the war could a bomber with a useful payload get from the US to Germany. European nations could reach other European nations with bombs all through the war, but the bomber was extremely vulnerable until fighters had drop tanks to let them fly far enough to escort bombers.
The P-51 was built in America, to British specifications, as part of the Lend-Lease Program. The British named it the Mustang; it was actually the American version that was the P-51 Mustang. The British name their aircraft; Americans number their aircraft.
George Seabrook Wing's idea
So...the bombers were too big to move as fast as German fighters. The English fighters, the P-51s, were too small to carry enough fuel to get far enough to attack German fighters. If the bombers were made smaller, they couldn’t carry bombs. If the fighters were made bigger, they couldn’t keep up with German fighters.
What could possibly be done? Well, there was an engineer, named George Seabrook Wing, who had started working on airplanes for the Martin company (now Lockheed Martin) when he was only 16. He had an idea for making better rivets. Rivets are the things that hold an airplane together, much as nails hold wood together, except that rivets aren't pointy-ended; they get hammered together. George Seabrook Wing called his rivets "Hi-Shear", and they worked better than the rivets that had been holding P-51s together, and weighed only 2/3 as much as other rivets.
The P-51 Test
How much weight in a whole lot of rivets?
1/3 of a rivet is not much difference in weight, the same way one nail is practically nothing to hold in your hand. A package of nails is a good solid weight, though.
There are a lot of rivets in a P-51. A whole lot more than there are nails in a package of nails. When the mechanics got done changing all the rivets in a P-51 to George Seabrook Wing’s rivets, the P-51 was a lot lighter. So much lighter that the P-51 manufacturers realized the P-51 could now carry a whole other fuel tank. So they gave it one. Now the P-51 could go further.
How much further? The P-51 was tested by flying it from Dayton, Ohio, to Albuquerque, New Mexico, and back. Without stopping. The not stopping part was important, because Dayton to Albuquerque was a test for London to Berlin. The Germans probably weren't going to be willing to refuel a P-51 landing in Berlin.
To make sure the test covered realistic flight conditions, the P-51 fired its guns over Albuquerque.
The historical weight of a rivet
Because of a rivet, the P-51s could fly to Germany - and back.
Because of the P-51s the bombers could fly to Germany - and back.
Because of the bombers, bombs could land on Germany.
Because the bombs were landing on German factories and fuel lines and railway lines and things like that, the Third Reich eventually would surrender.
Because the Third Reich surrendered, Europe was saved.
And all because of an aircraft rivet.
Mary Feik and Charles Seabrook Wing
I heard this story from Mary Feik, whose own life would make a bunch of interesting articles. She overhauled her first engine at the age of 13 and taught aircraft maintenance to crew chiefs and mechanics in World War II; she was only a teenager but knew well what she was doing as her father was a mechanic. She earned the Charles Taylor Master Mechanic award, which is named for the Wright brothers' mechanic, who was doing his work only a couple decades before Mary Feik was born.
George Seabrook Wing kept inventing things, started several aerospace businesses of his own, won NASA's Apollo Achievement Award and even built his own sport airplane with a range of 1000 miles.
Questions & Answers
How much did the p51 unpopulated airframe only weigh?
I'm sorry I don't have that information myself at the moment; Wikipedia says 7,635 pounds.