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You mean the lower speed of sound?Don't forget propeller efficiency falls off with altitude.
The cruise speeds seem above the stall speedsA main consideration may be wing lift.
Strange how such common sense variables have a way of being forgotten.You also have the needs of formation flying in which the formation has to travel at the speed of the slowest aircraft and not only the slowest aircraft in the squadron/group but you have to plan the flight with the possibility that the slowest plane is on the outside of the formation on about 1/2 of the turns the formation makes.
So they were starting out at 33,000 or even greater?I have heard and read that B-29 operations started "high" but bombing accuracy was not all that great, sometimes due to heavy cloud cover, so they started coming in at 30,000 - 31,000 feet, and then started a slight descent to bomb at higher airspeeds and lower altitudes. The lower release altitudes materially increased bombing accuracy.
That's a smart move, the Germans did the same thing with their Greifs, though they could dive fasterIn the last few months, I have heard they were routinely releasing at 18,000 - 25,000 feet most of the time (mostly low 20's, but sometimes releasing as low as 10,000 feet or so) while moving along at 335 mph or faster in the descent. It made interception difficult and a second firing pass VERY difficult since most Japanese interceptors had top speeds near 350 - 370 mph, making for a very good shot for the B-29 tail gunners when closing speeds were low.
You mean the lower speed of sound?
The cruise speeds seem above the stall speeds
The Merlin III was a single speed engine.
The throttle is part closed at sea level and then gradually opens up, maintaining the boost level, until it reaches critical altitude - known as full throttle height (FTH) in the UK - at which point the throttle is fully open. Above that altitude the boost cannot be maintained, so power falls away.
As the boost levels for cruise and maximum power the FTH is very similar.
I'm not sure what the curve at the left is.
A couple of things here:That's a smart move, the Germans did the same thing with their Greifs, though they could dive fasterI have heard and read that B-29 operations started "high" but bombing accuracy was not all that great, sometimes due to heavy cloud cover, so they started coming in at 30,000 - 31,000 feet, and then started a slight descent to bomb at higher airspeeds and lower altitudes. The lower release altitudes materially increased bombing accuracy.
In the last few months, I have heard they were routinely releasing at 18,000 - 25,000 feet most of the time (mostly low 20's, but sometimes releasing as low as 10,000 feet or so) while moving along at 335 mph or faster in the descent. It made interception difficult and a second firing pass VERY difficult since most Japanese interceptors had top speeds near 350 - 370 mph, making for a very good shot for the B-29 tail gunners when closing speeds were low.
I get that aspect - but why is the critical alt speed lower in the Spitfire chart while being higher in the Lancaster chart (M & S ratio)? Maybe without knowing the engine settings for sure it's not much use.
Leftmost curve is best climb speed.
For maximum power the FTH has gone from 18,500ft with +6.25psi bost to 13,000ft at +12psi boost and just under 7,500ft for +16psi boost.
The Merlin 45 and the Merlin XX used the same supercharger except for the 2 speed drive.
Merlin III and Merlin X used the same supercharger.
Be wary of comparing speeds at altitude between planes as the speed affects the critical altitude due to RAM.
A Hurricane and Spitfire have different critical altitudes (FTH) due to different speeds let alone a bomber.
This can easily be seen in looking at the charts for even the same plane for climb and for level speed.
a given boost level (say 6lbs) can be held several thousand feet higher in level speed vs climb speed due to the forward speed creating a higher pressure in the intake duct before the carburetor. a Spitfire had a higher critical altitude by around 1500ft than a Hurricane in level flight due to it's 40mph higher speed creating higher pressure in the intake duct.
This was a departure from precision bombing to area bombing and the beginning of the firebombing campaign.
If you're referring to the dam raids, they had a mix of results.I think a couple of Lancaster Squadrons would disagree with you there.
The Lancasters did do some good work with Tallboys and Grandslams but the dropping altitude was something under 20,000ft wasn't it?