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This I already know. I guess it's possible to calculate tip-speed based on RPM -- I'd almost swear I saw it come up on this forum somewhere actually, though I'm not sure what the norm was based on the time.There are a few things that are significant, the prop tip cannot go supersonic, the fewer blades there are the better and the aircraft must be able to take off and land.
If I can provide the aircraft, can somebody help me clarify these things?
Not for the first time I don't know what you want, I though I gave you the ratios for the Merlin?This I already know. I guess it's possible to calculate tip-speed based on RPM -- I'd almost swear I saw it come up on this forum somewhere actually, though I'm not sure what the norm was based on the time.
From what it appears K.5083 (prototype) used a Merlin C driving a propeller that is presumably 11.03" (though I could be wrong here). I know nothing about the Merlin-C; the early Mk.I's were using the Merlin II with a twin-pitch prop of 11.03" in diameter
Sounds great... this is going to be a long list but here it goesI can help with American engines. Please supply a list of the engine models, including the dash numbers (i.e., R-1820-97), for the aircraft that interest you.
So regardless of the exact propeller, the gear-ratio is exactly the same? The engines in question were the Merlin C, Merlin II and Merlin III since I'm basically covering the Hurricane Prototype and the early Mk. I at this time.Not for the first time I don't know what you want, I though I gave you the ratios for the Merlin?
As far as I can see the ratios weren't changed in the early days. The early Spitfire prototype had its prop changed when it was slower than expected (and I believe slower than the Hurricane).So regardless of the exact propeller, the gear-ratio is exactly the same? The engines in question were the Merlin C, Merlin II and Merlin III since I'm basically covering the Hurricane Prototype and the early Mk. I at this time.
"holy shit, you're fucking nuts man!".
I'm not really sure if the gear-ratios are varied in different aircraft with different propellers or just the same across the board. I don't know if there are any rules of thumb used or even where to go and find such esoteric material.
I might have some more to add later ...
So the variances are all listed here for aircraft that are listed?They vary widely
The data you want is in the third row of the third last column.
That's good to know if I can find it...For other engines I would suggest find a library which has a Janes AWA from the years the engine you want was produced and look in the engine section of that
Just to be clear -- these numbers apply for every application of the engine?So the variances are all listed here for aircraft that are listed?
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I was posting a thread on WWII aircraft rate of turns and I started computing up a rate of advance ratios which are helpful in determining thrust levels for sustained turns. That said I was planning on listing a variety of fighter planes. At first I computed everything on the premise of propeller RPM and engine RPM being the same thing, which turns out to be totally wrong in most cases.
I'm not really sure if the gear-ratios are varied in different aircraft with different propellers or just the same across the board. I don't know if there are any rules of thumb used or even where to go and find such esoteric material.
If I can provide the aircraft, can somebody help me clarify these things?
There are a few things that are significant, the prop tip cannot go supersonic, the fewer blades there are the better and the aircraft must be able to take off and land.
I was posting a thread on WWII aircraft rate of turns and I started computing up a rate of advance ratios which are helpful in determining thrust levels for sustained turns. That said I was planning on listing a variety of fighter planes. At first I computed everything on the premise of propeller RPM and engine RPM being the same thing, which turns out to be totally wrong in most cases.
I'm not really sure if the gear-ratios are varied in different aircraft with different propellers or just the same across the board. I don't know if there are any rules of thumb used or even where to go and find such esoteric material.
If I can provide the aircraft, can somebody help me clarify these things?
I was posting a thread on WWII aircraft rate of turns and I started computing up a rate of advance ratios which are helpful in determining thrust levels for sustained turns. That said I was planning on listing a variety of fighter planes. At first I computed everything on the premise of propeller RPM and engine RPM being the same thing, which turns out to be totally wrong in most cases.
I'm not really sure if the gear-ratios are varied in different aircraft with different propellers or just the same across the board. I don't know if there are any rules of thumb used or even where to go and find such esoteric material.
If I can provide the aircraft, can somebody help me clarify these things?
The counterweight type propellers both British and US had similar ranges, about 20 degrees of travel. When they went to the Hydraulic or Electric pitch change is when they got a larger travel range, for both British and US propellers.I would also note that many times the two position prop was used as follows.
Put in fine pitch, start take-off run, clear runway and retract landing gear, shift propeller to coarse pitch leave it there until the plane is back on the ground!!!!
Spitfires for instance switched to coarse pitch once they hit 140 IAS right after take-off, this is below best climb speed. Climb was done in course pitch.
I would also note that you need to find out the actual pitch of of the props, some British constant speed props only had 20 degrees of travel while some others (and many american props) had 30 degrees of pitch adjustment.
You had a real good propeller if you were getting 80% efficiency from it in most flight regimes so spending a crap load of time figuring out some of this stuff might not actually tell you mutch.
WITHOUT diving into the mathematical rabbit hole? If that's without diving into it, I shudder to think what isIn addition to that data, if you wish to find propeller efficiency and net thrust without diving into the Mathematical Rabbit Hole, download and check out "Propeller Performance Charts for Transport Airplanes", NACA-TN-2966
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930084064.pdf
Using this, you'll also be factoring in Activity Factor, Number of Blades, Single or Dual Rotation, and Mach Number effects.
Yeah but the WW2 Aircraft Performance page largely has the TAS/IAS figures and the RPM data. I figured I was just going to compute the RPM for the engine if I could find the reduction gear ratio for the Merlin C and Merlin II; then simply use the regular advance-ratio formula.This will have a big effect on Early Spitfires and Hurricanes, Most Ki-43s and others of that ilk.
WITHOUT diving into the mathematical rabbit hole? If that's without diving into it, I shudder to think what is!
Yeah but the WW2 Aircraft Performance page largely has the TAS/IAS figures and the RPM data. I figured I was just going to compute the RPM for the engine if I could find the reduction gear ratio for the Merlin C and Merlin II; then simply use the regular advance-ratio formula.