Why the heck did they design it that way?

[swampyankee]

Is it known when the Air Ministry decided to pursue the Hispano as a replacement/compliment to the .303? Must have been in the late 1930's, as they were being trialed in 1940

According to Tony Williams, it was in the early to mid 1930s, after trialing the 0.50 in Browning and determining it was barely more effective than the 0.303 in used by the RAF. I really don't have a stake in this, but it seems the RAF determined that the 0.50 in was unable to cause sufficiently greater damage to overcome its considerably greater weight and lower rate of fire.

 

[Shortround6]

lbs or £?

sorry, the latter. English pounds (money)
Keyboard doesn't have the "pound" symbol and pulled a brain fart.

 

[Clayton Magnet]

According to Tony Williams, it was in the early to mid 1930s, after trialing the 0.50 in Browning and determining it was barely more effective than the 0.303 in used by the RAF. I really don't have a stake in this, but it seems the RAF determined that the 0.50 in was unable to cause sufficiently greater damage to overcome its considerably greater weight and lower rate of fire.

Thank you for the link, very informative. Looks like the 20mm was chosen as the successor to the .303 in the 1920's, but wasn't until 1935 that the Hispano was selected to be the model they wanted.
"... A firing demonstration of a prototype to British officers in Paris in 1935 banished all thought of the Oerlikon; the Hispano was similar in size and weight, slightly more powerful and fired nearly twice as fast. Unfortunately, the processes of obtaining approval to buy the gun, setting up a subsidiary Hispano factory at Grantham (the British Manufacturing And Research Company, or BMARCO), redrawing the gun to imperial rather than metric units, testing and debugging the prototypes, then fitting them into aircraft and debugging the installations, all took too long for the cannon to achieve anything in the Battle of Britain..."

 

[pbehn]

lbs or £?

sorry, the latter. English pounds (money)
Keyboard doesn't have the "pound" symbol and pulled a brain fart.

Without a £ symbol most use GBP.

 

[Shortround6]

Thank you.

 

[PWR4360-59B]

Its too bad they didn't understand super sonic airframe design when the P51 was on the drafting table. Swept back wings and fully controllable horizontal stabilizers and all that. Then when going sonic in a dive they would take it, and give a huge speed advantage.

 

[Clayton Magnet]

Don't think that is possible in a propeller driven aircraft.

 

[PWR4360-59B]

Many where lost in sonic dives because of reverse controls and wing design.

 

[pbehn]

Many where lost in sonic dives because of reverse controls and wing design.

The flying tail as it was known was trialled on spitfires, there is a lot more to it than simply sweeping the wings back, you need different wings and a different air frame.
RAE Bedford (RAE) modified a Spitfire for high-speed testing of the stabilator (then known as the "flying tail") of the Miles M.52 supersonic research aircraft. RAE test pilot Eric Brown stated that he tested this successfully during October and November 1944, attaining Mach 0.86 in a dive.[128]

 

[GregP]

Regarding post 288, NONE were lost in supersonic dives. All they did was exceed their critical Mach number with going supersonic (transonic), where LOCAL supersonic flow started to occur.

Still, it WOULD have been great if they understood the transition better and could partly compensate and get higher critical Mach numbers. Methinks digital computers came a bit late for that.

 

[wuzak]

Its too bad they didn't understand super sonic airframe design when the P51 was on the drafting table. Swept back wings and fully controllable horizontal stabilizers and all that. Then when going sonic in a dive they would take it, and give a huge speed advantage.

So, design an aircraft around a particular flight regime that it was unlikely to encounter, and if it did it would likely lose something important - like the propeller?

Sounds like a winning design philosophy!

btw, in high speed dives, Spitfires experienced lost propellers and exploding superchargers, among other, more successful, dives. The engines in these Spitfires were 60 series Merlins, just like the ones in the P-51.