Shortround6
Major General
Well, your eminent BoB historian had better get his facts straight, that or cut out the bias.
"The third crucial advantage was its fire-power – 55 seconds' worth of ammunition compared with 14.7, and 20mm high explosive cannon shells as well as machine-guns, cannons that even without their explosive charge packed a punch 200% heavier than a .303 bullet."
A Spitfire only got 14.7 seconds worth of firing time if the guns were firing faster than 1200rpm. They were generally rated at 1100-1200rpm. At even 1160rpm that is 15.8 seconds. Granted this is a minor quibble but the 109s oh so superior fire power of 55 seconds is for TWO guns, not eight. The cannons ran out of ammo after 7-8 seconds. No mention of that is there?
To be fair the 20mm shells, even without explosive are way more powerful than 200% but the Germans have a slight problem at any but the closest of ranges. The 20mm and the 7.9mm mgs have different times of flight. At sea level the 20mm shells take 1/10 of second longer to get to 300 meters. The difference is less at higher altitudes but a 300mph aircraft can cover 44ft in a 1/10th of second. This makes deflection shooting a bit difficult.
I would also seriously question the claim that the 109 climbed faster. They did climb differently. The 109 climbed at a steeper angle which to pilots in combat appears to be climbing better. The Spitfire covered more horizontal ground while gaining about the same or slightly more altitude per unit of time.
One also has to be very careful when comparing printed tests as you will very seldom find a test for a Spitfire (or any British plane) climbing at combat power. For example this chart
http://www.spitfireperformance.com/n3171climb-c.jpg
was done at 2600rpm and 6 1/4 lbs boost which is why the boost falls off at around 11,000ft. This was pre BoB and by the time of the BoB not only was the boost limit changed to the well known 12lbs but the 30 minute climb rating was changed from 6 1/4 lbs at 2600rpm to 6 1/4 lbs at 2850rpm. Combat climb at 3000rpm would have been? even without the 12lbs of boost.
He also managed to leave out that the Spitfire was faster in level flight.
"The third crucial advantage was its fire-power – 55 seconds' worth of ammunition compared with 14.7, and 20mm high explosive cannon shells as well as machine-guns, cannons that even without their explosive charge packed a punch 200% heavier than a .303 bullet."
A Spitfire only got 14.7 seconds worth of firing time if the guns were firing faster than 1200rpm. They were generally rated at 1100-1200rpm. At even 1160rpm that is 15.8 seconds. Granted this is a minor quibble but the 109s oh so superior fire power of 55 seconds is for TWO guns, not eight. The cannons ran out of ammo after 7-8 seconds. No mention of that is there?
To be fair the 20mm shells, even without explosive are way more powerful than 200% but the Germans have a slight problem at any but the closest of ranges. The 20mm and the 7.9mm mgs have different times of flight. At sea level the 20mm shells take 1/10 of second longer to get to 300 meters. The difference is less at higher altitudes but a 300mph aircraft can cover 44ft in a 1/10th of second. This makes deflection shooting a bit difficult.
I would also seriously question the claim that the 109 climbed faster. They did climb differently. The 109 climbed at a steeper angle which to pilots in combat appears to be climbing better. The Spitfire covered more horizontal ground while gaining about the same or slightly more altitude per unit of time.
One also has to be very careful when comparing printed tests as you will very seldom find a test for a Spitfire (or any British plane) climbing at combat power. For example this chart
http://www.spitfireperformance.com/n3171climb-c.jpg
was done at 2600rpm and 6 1/4 lbs boost which is why the boost falls off at around 11,000ft. This was pre BoB and by the time of the BoB not only was the boost limit changed to the well known 12lbs but the 30 minute climb rating was changed from 6 1/4 lbs at 2600rpm to 6 1/4 lbs at 2850rpm. Combat climb at 3000rpm would have been? even without the 12lbs of boost.
He also managed to leave out that the Spitfire was faster in level flight.