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#4438923 - 09/14/18 12:37 PM Prop Pitch function question  
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Robert_Wiggins Offline
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Is the "Prop Pitch feathered" function, the reverse of the "Prop Pitch Increase" function? Is it stepped by repeated key pressing?

Best Regards


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#4438979 - 09/14/18 05:27 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Originally Posted by Robert_Wiggins
Is the "Prop Pitch feathered" function, the reverse of the "Prop Pitch Increase" function? Is it stepped by repeated key pressing?

Best Regards


Feathering is full fine and is normally used to reduce drag when the engine is shot out.

#4438998 - 09/14/18 07:35 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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The incremental prop pitch commands appear to be 'P' for increase and "shift+P" for decrease. I have yet to see anyone explain how the prop pitch would be properly used in-game (but hope someone will).

#4439011 - 09/14/18 09:06 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Thanks Space_Ghost, I agree that is what feathering means but in my question I am trying to determine if one press of the key gives you full fine or do you have to repeatedly press it to step down to full fine. There is no visual to determine what the progress is when you use the key.


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#4439018 - 09/14/18 09:34 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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According to the long list of airplane stats on the right - Feather sets it to 22 degrees. with the single combo button push.
From my google, I thought a feathered prop was 90 degrees. (maybe it was the wrong google.)
The axis for prop pitch is from 22 degrees to 80 degrees. Well at least on the 109...)

Hurricane range is 23 to 58 degrees and feather sets it to 23.

Last edited by Stache; 09/14/18 09:39 PM.

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#4439042 - 09/15/18 12:36 AM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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BirdDogICT Offline
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Robert_Wiggins,

Look on the left side of Hurricane cockpit...pitch level is fully animated.

Similarly, pitch indicator dial of the 109 is located on the lower left of instrument panel.


Attached Files Untitled3.pngUntitled4.png
Last edited by BirdDogICT; 09/15/18 12:46 AM. Reason: Additional info

There are no accidents and no fatal flaws in the machines; there are only pilots with the wrong stuff.

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#4439057 - 09/15/18 04:18 AM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Ah, thanks BirdDog and Stache for that info. I will check it out next flight.

Best Regards


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Case: Cooler Master Storm Trooper
PSU: Ultra X3,1000-Watt
MB: Asus Maximus VI Extreme
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#4439062 - 09/15/18 05:19 AM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Wow, good catch!


The older I get, the more I realize I don't need to be Han, Luke or Leia. I'm just happy to be rebel scum...
#4439134 - 09/15/18 06:18 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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#4439151 - 09/15/18 08:28 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Cleaning up some of the definitions will help here:

Fine Pitch is the smallest blade angle. It gives the least resistance to the turning of the engine and thus the highest RPM. This position also presents the most blade surface area to the oncoming air, and thus creates more drag.

Coarse Pitch is the largest blade angle. It gives the most resistance to the turning of the engine and thus the lowest RPM. This position presents the least blade surface area to the oncoming air, and thus creates less drag.

Feathering the propeller isn't actually possible on most single engine aircraft, including these (though the Bf 109 gets close). In the feathered position the minimum blade surface is presented to the oncoming wind and thus the propeller creates the least possible drag in a situation where the engine has failed or been shut down. Typically the pitch angle is in the 85-90 degree range.

These aircraft all have constant speed propellers installed. This means there is a governor in the picture as well. When you move the propeller control, you are NOT adjusting the pitch of the propeller blades, at least not directly. What you are actually doing is telling the governor what RPM you want the engine to turn at. The governor adjusts the propeller blade pitch automatically to hold the desired RPM, compensating for changes in engine power, airspeed, and air density (altitude), all of which effect what position the blade must be at to produce a given RPM. You may see fluctuations in RPM when any of these things are changing as the governor tries to adjust the blades to meet the new demand. If the governor has moved the blades all the way to the fine or coarse pitch limit, it has reached the limit of what it can compensate for, and thus RPM will go over speed (if it has you blades on the coarse pitch limit) or under speed (at the fine limit) until the operating conditions call for a blade angle within the blade travel range again.

Early versions of both the Hurricane and the Bf 109 did not have a constant-speed propeller or governor, but did have a control to manually adjust the propeller pitch (you can imagine the workload that was for a pilot in a dogfight). When the Bf 109 got a constant speed propeller, a switch was retained to allow the pilot to manually control the blade pitch as desired. This is why it had that gauge which noted the actual position of the blades.

As for normal operation, don't get hung up on the drag issue. More RPM is always more power, speed, and climb rate, and more than compensates for the drag penalty of having the blades at a finer pitch. So 3,000 RPM is best for your Hurricane when you need max performance. No engine on earth can give max performance forever, not to mention that your flight will be quite short with all the gas you'll guzzle running at 3,000 RPM all the time. So at cruise, dial it back, 2,600 is the max cruising RPM, but you can go lower if you want. You do want to avoid excessively low RPM when running with a high throttle setting, as this puts a lot of strain on the engine. This means that on the ground and during takeoff, the prop control should always be in the max RPM position, except to check operation of the prop control on the ground prior to takeoff. When you land, you should also make sure you have the prop in the max RPM position, because if you need to go around, you want the governor ready to give you everything it's got as soon as you slam the throttle forward. It's also bad to slam the throttle forward when you have selected a lower RPM with the prop control. Actually, you shouldn't be slamming the throttle forward at all - be smooth. Engines like smooth pilots.

Now, back to the drag issue. There are times when you can manipulate how much drag your prop is producing to your advantage. On a descent towards your airfield to land, you want to lose speed and altitude. It's easy to do one at a time, but to do both you need to add drag. You're still going too fast to use your flaps - they'll jam or even rip out. Bring your throttle way back (but not less than 1/4 open - that's also hard on the engine) and bring the RPM as high as it will go. Eventually as you slow down the governor will have it all the way on the fine pitch stop and RPM will drop as airspeed drops, but that doesn't matter. The point is you've got the blades acting as an air brake for you. This is standard procedure in the real world when you have an engine fire - you need to get the plane on the ground RIGHT NOW, but don't want to be going so fast once your dive is over that you can't land.

If you lose your engine and have turned into a glider, you can set your prop control to give minimum RPM, and thus minimum drag to extend your glide. As you get close to your landing spot, if your prop is still windmilling you can set your control to get max rpm if it looks like you're going to overshoot your spot and hit a titanium fence. On the Hurricane, the governor used engine oil pressure to move a piston that pushed on the blade change mechanism to adjust the blades, so if your engine is no longer turning, there is no oil pressure and no way for the governor to adjust the blade pitch. On the Bf 109 it was an electrical system, so blade angle could still be changed with the engine stopped, but I don't think WOTR has modeled this.

There's more to say on this, but there's the basics.

#4439153 - 09/15/18 09:01 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Gecko,

Exactly so. Good discussion of the basics.

For the Hawker historians of the group, by 1940, practically all hurricanes had constant speed props of several types.:.

1940 Hurricanes can be seen with either the De Havilland propeller/spinner or the Rotol prop.. The Merlin Mk.III could take either, so it was only a prop change, but practicalities suggest that units would standardise to save on spares. The prime reason for more than one supplier was in case, for whatever reason (enemy action being predominant), a source of supply was cut off of one particular design. There wasn't any major performance advantage for any particular type though servicing and repairs differed between different designs and constructional materials.

Initially there was a considerable advantage to be gained using the Rotol propeller: it was a constant-speed unit rather than the DH variable pitch propeller, which could only be used in the two extreme positions (fine and coarse pitch). The Rotol propeller was initially allocated to the Hurricane because it was thought to be more in need of improvement. At the same time a programme was set in motion to redesign the DH propeller from vp to constant speed: this resulted in a kit being produced which was fitted to Fighter Command's aircraft (those still with vp props) in July 1940. After this time the performance difference between the two was small.

A Ministry of Aircraft Production memo dated 29th June 1940 noted "...the Hurricane I aircraft now being delivered from the manufacturers all have Rotol constant speed airscrews" and that "...the De Havilland two-pitch airscrews on Hurricane I aircraft are due to be modified when Spitfire I aircraft have been completed" ( Air 2/2822). Operations Record Books note delivery of Rotol/constant speed propeller equipped Hurricanes in the April – June 1940 period (see for example 1, 79, 151, 213 squadrons). Books from Richey, Gleed and Neil also mention that new Hurricanes came equipped with Rotol constant speed propellers prior to the Battle of Britain.


There are no accidents and no fatal flaws in the machines; there are only pilots with the wrong stuff.

— Tom Wolfe, The Right Stuff,1979.
#4439199 - 09/16/18 07:26 AM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Feathering is not a setting you can access under normal conditions or by normal use of the pitch lever in a Hurricane.

Most aircraft have a detent in the prop groove where the lever slides that allows the propellor to be feathered or (in modern aircraft) even reversed. The detent is there because it's a mechanical "gate" that prevents the inadvertent setting of an undesirable mechanical function. (If feathered in normal flight the stress on the propellor would be too high which would certainly cause all kinds of problems like shifting your car int reverse while travelling forwards at 80). The Hurricane's governor only allows pitch to be manipulated within a region of motion that makes sense for normal operation, since there is no detent on the prop/throttle quadrant that indicates such a thing as being possible the ability to fully feather the prop is not present.

Moving the lever to fully coarse is probably going to be your best bet for minimising drag in the Hurricane if you have to glide it.


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#4439257 - 09/16/18 06:18 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Thanks guys for the excellent information. I am really learning a lot about prop pitch. Who says video games aren't educational?

So to use this in the game....
I take off with fine pitch and full throttle, kind of like how you start out in low gear in a car.
Once airborne, I increase the pitch to 'bite' harder into the air for maximum climb and also to lower my rpms to 3000 so the engine doesn't over-rev. (like shifting into a higher gear on a car)
Once at altitude, I adjust pitch to keep rpms around 2600 to save fuel and be kind to the engine.

Now a few questions...
If I need to fly at less than max possible speed (i.e. fly slower to stay in formation) while climbing and cruising do I just throttle back and leave the pitch setting where it is (i.e. somewhat coarse), or do i have to juggle both throttle and pitch somehow.?
If we meet enemy aircraft and a dogfight ensures, how is prop pitch used? Do I just leave it at the same pitch we were cruising on and let the governor figure it out, or am I fiddling with prop-pitch as we fight?

#4439268 - 09/16/18 08:50 PM Re: Prop Pitch function question [Re: 77_Scout]  
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Simple answer,

Fine Pitch (lever up) for take-off and landing and below 2000ft or in climbs. On takeoff, once the plane reaches 180mph, switch to coarse pitch.

Course Pitch (lever down) is for climb, dive, level flight and combat.

For the Hurricane Mk1 (Rotol), 2600rpm (+3 boost) is good for "unlimited cruise power" with radiator partially open, 3000 rpm (+6 boost) is good for "5 minute power",
2750 rpm is good for continuous climb, although this must be reduced at high altitude.


There is lots of information on engine settings and performance characteristics on fan sites for other Battle of Britain style sims....much of it is hotly debated. FWIW, Air Tactical Assault Group website has a lot of good general info on flying BOB aircraft, although I'm not sure how much is applicable to WOTR. I'm still testing how these aircraft are modeled in WOTR, frankly, I'm having a lot of fun just flying without the constant overly fussy engine management found in some other sims.

Last edited by BirdDogICT; 09/17/18 03:51 AM. Reason: Typos

There are no accidents and no fatal flaws in the machines; there are only pilots with the wrong stuff.

— Tom Wolfe, The Right Stuff,1979.
#4439272 - 09/16/18 09:26 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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So far as I have seen you can cruise all day at 2,700RPM and full boost without the oil and radiator temperatures exceeding safe levels. What you really want to watch is your temperature gauges, so maintain your forward speed and manage your radiator shutter to keep them below boiling and you should be fine, it's not like CloD where your engine will seize at the drop of a hat.

Last edited by Ace_Pilto; 09/16/18 09:26 PM.

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#4439279 - 09/16/18 10:15 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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77 - don't think of it in terms of selecting a pitch, but rather as selecting an RPM.

3,000 RPM is the max the governor will allow, so when the lever is fully forward, you are telling the governor you want 3,000 RPM. This is max performance in any situation as far as the prop is concerned. Overreving is not really a concern unless you're in a high speed dive. 2,850 RPM is called out for climb, but this is out of consideration for the health of the engine over an extended climb. 3,000 RPM will still get you better performance in the climb, it's just not nice for your engine to keep it there all the way up to 20,000ft. I'm under the impression that BoB pilots regularly exceeded the time limits for the various power settings to meet the demands of combat. Dowding sent out a memo at one point imploring pilots not to do so due to the fear of a shortage of new engines developing.

For formation, I'd set RPM to 2,600 (less if I'm concerned about fuel), and use throttle to keep pace with my flight. When the enemy is spotted, go straight to max RPM and max throttle. Use WEP if needed.

#4439528 - 09/18/18 02:37 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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I'm curious as to what is modelled on this, I've never had any engine failure other than after bullet strikes. It does seem you can just run at full blast indefinitely, is that the case?

#4439620 - 09/18/18 10:05 PM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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Yikes....as if there weren't enough to do in the office already!!! Hoping for an "auto" function for us challenged pilots......great info though....thank you!

#4439639 - 09/19/18 12:53 AM Re: Prop Pitch function question [Re: ChiefWH]  
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Originally Posted by ChiefWH
I'm curious as to what is modelled on this, I've never had any engine failure other than after bullet strikes. It does seem you can just run at full blast indefinitely, is that the case?


I have burned out the engine in the 109 running full power constantly without opening radiator..
Eventually the temps do rise - when it gets to the end of the dial, the engine will slowly loose power and die.

And there is a limited amount of WEP available in the 109.

Last edited by Stache; 09/19/18 12:54 AM.

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#4439693 - 09/19/18 11:11 AM Re: Prop Pitch function question [Re: Robert_Wiggins]  
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We should have the ability to run the E4 on either automatic or manual setting, as per real life.
I wonder, the way it is now with only manual control of radiator and prop pitch, if we will have an auto setting at a later date...

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