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Actually Kestrels were available with .632, .553 and .477 gears depending on intended use.It seems the Merlin C and Merlin II's gear ratios were 0.477. There was an earlier engine, the Kestrel which was 0.55
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.
Was there any possibility of the Merlin-C being built for a ratio of 0.420? I'm curious because it seemed to be mentioned on a website that describes the first flight of the Hawker Hurricane.
Not sure honestly, but there were several variants of the Merlins and I was trying to whip up an advance ratio chart for as many fighter planes as I can find data on as you can use the data to produce thrust figures.Why???
This is probably going to be a dumb question, but where do you find torque values for the Merlin variants I listed. World War II Aircraft Performance doesn't list these figures...Horespower = (torque x rpm) / 5,252
So, at 5,252 rpm, torque = HP. Below 5,252 rpm, torque rules. Above 5,252 rpm, HP rules.
Why do you need them?
HP = Torque x RPM ÷ 5252
If you know HP you can calculate for torque.
Engine dynamometers measure torque directly and the readings have to be converted to horsepower ( some radials had torque meters built into the reduction gears and flight engineers could read torque on a meter.
1030hp Merlin III is making 1796.32 ft lbs of torque at 3000rpm.
At take-off it is making 880hp so the torque is 1534.72ft/lbs. Cylinders aren't getting the full effect of the 6 lbs of boost because the throttle is closed down so much choking the engine.
And so on, if you know the HP at a certain rpm then you know what kind of work the engine can do, effort over time.
It's not so much that you're choking the engine per se, but the supercharger is compressing to what would be, at full airflow, an intake manifild pressure of anout 10-11 lbs, and you're paying the cost in horsepower to drive the supercharger.
Sorry, I realized it after I posted...Why do you need them?
So if I know the HP at one point across the performance envelope, I can calculate all the others?If you know HP you can calculate for torque.
While this is probably not necessary, but a pure hypothetical: The prototype listed a critical altitude of 16200' which is also where RPM peaked. For some reason, which I cannot understand, 1029 HP @ 11000 feet is listed as being the horsepower the engine is rated for. Did it gain 5200 feet of ram? Or is there something I don't get?1030hp Merlin III is making 1796.32 ft lbs of torque at 3000rpm.
...
While this is probably not necessary, but a pure hypothetical: The prototype listed a critical altitude of 16200 horsepower which is also where RPM peaked. For some reason, which I cannot understand, 1029 HP @ 11000 feet is listed as being the horsepower the engine is rated for. Did it gain 5200 feet of ram? Or is there something I don't get?
So if I know the HP at one point across the performance envelope, I can calculate all the others?
Sorry, I realized it after I posted...
Okay, I have the following figures available for K-5083, it's just a test run to make sure I'm getting numbers right.HP = Torque x RPM ÷ 5252
If you know HP you can calculate for torque.
Engine dynamometers measure torque directly and the readings have to be converted to horsepower ( some radials had torque meters built into the reduction gears and flight engineers could read torque on a meter.
Okay, that definitely makes more sense out of things, I computed the same results as you did.first, keep things simple. get rid of the reduction gear number
How do you do that?Now that you know what the engine is doing you can figure in the prop reduction gear to get the torque going to the propeller.