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I figure used in an aircraft for a starting point.
I would have figured they'd have just built another factory to be honest.
the original idea was to simply use 2 x V-1710 blocks, and it started out as an X-cylinder engine, but for one reason, it ended up as a W.
Why was this?
I have no idea, the world of propellers is lost on me, it is a science in itself. I do know that an engine that is shut down with an un feathered prop causes massive drag. But that is my limit of "expertise".Re: He 177 Grief
Hang on, I thought the drag was the installation (carburetor intake, radiator, oil-cooler) not the propeller? Is a larger propeller similar in effect to a wing with higher aspect ratio?
Regardless, I would have figured that higher drag would be beneficial in the dive phase as it acts like a brake a little bit. I'd have figured the problem would be during the cruise phase.
Commonly known as "windmilling". Akin to using engine braking to slow a motor vehicle. A similar phenomenon exists when an airplane wants to go faster (perhaps in a dive) than the speed its propeller governed at redline and full throttle would naturally pull it. Now the tail is wagging the dog and the prop is creating lots of drag and abusing the reverse thrust bearing in the engine, which in engines not designed for reversible props is often much less robust than the main thrust bearing, if it exists at all.I do know that an engine that is shut down with an un feathered prop causes massive drag.
That bit I understand, its when it comes to how a constant speed prop behaves when overspeeding in a dive I havnt a clue. The proposition is that two large props are better than 4 small ones. I understand the logic of the argument having that braking effect close to the centre of gravity (and all the other centres too) is beneficial. But if some learned fellow were to propose that it was advantageous to have this breaking effect spread by four props along the wing, I would have to agree with that too because I just dont know.Commonly known as "windmilling". Akin to using engine braking to slow a motor vehicle. A similar phenomenon exists when an airplane wants to go faster (perhaps in a dive) than the speed its propeller governed at redline and full throttle would naturally pull it. Now the tail is wagging the dog and the prop is creating lots of drag and abusing the reverse thrust bearing in the engine, which in engines not designed for reversible props is often much less robust than the main thrust bearing, if it exists at all.
That's why planes like that are required to carry power in the dive, and if steep dive bombing, need some variety of aerodynamic speed limiting.
Now imagine an 80-90 thousand pound four engine bomber engaging in such antics and "diminishing returns" comes to mind, doesn't it?
Wright engines weren't famous for their strong reverse thrust bearings.while the technique worked on the Pratt and Whitney equipped B-26s, it didn't work so well on the Wright equipped B-25s.
No wonder! That's a great way to shock cool engines and crack cylinders.Pilots in the Aleutians learned to use the braking power of their propellers to decrease their landing rolls in B-26s. They would cut the engines on touchdown, then restart them when they needed the power to taxi. This got a few pilots in trouble when they rotated back to the States, where such unorthodox methods were frowned upon.
(Another restating the obvious!) If you have your braking effect props spread out, they become more susceptible to a slight imbalance in drag, especially in the outboard ones, making aircraft control and thus, bombing accuracy, difficult.But if some learned fellow were to propose that it was advantageous to have this breaking effect spread by four props along the wing, I would have to agree with that too because I just dont know.
Thats easy for you to say because you know what you are talking about, flaps and other devices are frequently spread along the wings, so if some fellow of letters was to say "four engines are advantageous in dive bombing due to the spanwise spreading of loads and limiting of maximum beam stresses" (or some other BS) I couldnt say that its wrong. Like the stuff you just posted about bearing loads and shock cooling, its all very complicated lols.(Another restating the obvious!) If you have your braking effect props spread out, they become more susceptible to a slight imbalance in drag, especially in the outboard ones, making aircraft control and thus, bombing accuracy, difficult.
Otherwise it's just comparative pi r□'s of the propeller disks.
So the matter is that the windmilling effect would produce higher drag in dives, which normally is good, but it would put excessive stress on the engine?Commonly known as "windmilling". Akin to using engine braking to slow a motor vehicle. A similar phenomenon exists when an airplane wants to go faster (perhaps in a dive) than the speed its propeller governed at redline and full throttle would naturally pull it. Now the tail is wagging the dog and the prop is creating lots of drag and abusing the reverse thrust bearing in the engine, which in engines not designed for reversible props is often much less robust than the main thrust bearing, if it exists at all.
Truthfully the dive-requirement was added only after the aircraft had passed the mockup. Early on the plane was configured to perform some degree of glide-bombing (the Germans called it light to moderate angle dive-bombing), which I'm unclear on the exact number (though 40-50 degrees was a figure I heard once).Now imagine an 80-90 thousand pound four engine bomber engaging in such antics and "diminishing returns" comes to mind, doesn't it?
Technically, that could be argued to say that even a twin-engined dive-bomber would have problems in that regard.If you have your braking effect props spread out, they become more susceptible to a slight imbalance in drag, especially in the outboard ones, making aircraft control and thus, bombing accuracy, difficult.
Were the DB 601 or Jumo 211/213 sturdy in that regard?Pilots in the Aleutians learned to use the braking power of their propellers to decrease their landing rolls in B-26s. They would cut the engines on touchdown, then restart them when they needed the power to taxi. This got a few pilots in trouble when they rotated back to the States, where such unorthodox methods were frowned upon. They also found that while the technique worked on the Pratt and Whitney equipped B-26s, it didn't work so well on the Wright equipped B-25s.
True, but the proximity of the engines to aircraft centerline tends to minimize that effect to remain within the corrective ability of the flight controls. Less so with outboard mounted engines.Technically, that could be argued to say that even a twin-engined dive-bomber would have problems in that regard.
I don't know about the technical details of the V-3420. Based on the performance of the prototype engines, which did pretty well, I think there were likely two related reasons it didn't go forward. First the R-3350 was a bit ahead in development and (2) without an earmarked plant by 1942, there was no place to build it. As it turns out, it wasn't needed and the powers that be made the right call.
For current typical single and twins, the coolests operating CHTs are at touch down. Even taxiing back causes the CHT's to rise again.No wonder! That's a great way to shock cool engines and crack cylinders.
Apples and oranges. Modern light aircraft in a temperate climate are not the same as heavy military aircraft operating in Alaska. The "incredible prostitute", aka "Baltimore sewer pipe", with its high wing loading would carry more power on its tightly cowled engines on the approach, and the much greater mass of the R2800 would be storing more heat. They ran hot anyway. Landing speeds were high and OATs were low; recipe for shock cooling if the engines were caged at touchdown. The effect is cumulative with repeated abuses. I've had experience towing gliders (Bird Dogs forever) and operating turbocharged planes at high altitudes in winter, as well as changing cracked cylinders. BTDT.I see no reason a similar behaviour would not be seen with the radials.
Shock cooling would be very unlikely in this scenario.