Propeller thickness

[[DBS]TH0R]

As far as I got you right :). DCS replaces the rotating blades with just a flat rotating plane(s) having a motion blurred texture ... up to a certain speed the propellers are set to invisible and the plane, I mentioned, to visible.

Same for the helicopter's Tail and mainrotor. Actually the motionblur for objects is given but it's too performance consuming.

 

I don't believe it is that much performance intensive. Even the old B-17 II the Mighty Eighth had better prop (pitch) animation than later released IL2 1946 which features nothing more than spinning 2D texture. Even if they just shape (make it thicker) the mentioned texture properly depending on what the governor is doing it would look better than this thin circle.

 

 

EDIT: Just checked on the HUEY - the tail rotor animation shows different pitch depending on the way you are turning.

Edited October 19, 2014 by T}{OR

[KLR Rico]

From what I can tell, the appropriate propeller animations are there, they're just not applied correctly.

 

I haven't done a whole lot of testing, but it appears that the problem we have is that the animation shows the blade pitch changing according to the RPM setting, as if the RPM control was the pitch control on variable pitch propeller, rather than varying with the needs of the governor as it should.

[winz]

From what I can tell, the appropriate propeller animations are there, they're just not applied correctly.

 

I haven't done a whole lot of testing, but it appears that the problem we have is that the animation shows the blade pitch changing according to the RPM setting, as if the RPM control was the pitch control on variable pitch propeller, rather than varying with the needs of the governor as it should.

No, the "problem", as mentioned above by Polychop Simulations, is that at some RPM the model of propeller is no longer rendered and replaced by a simple cylinder with a texture (that looks like a blurred propeler). No animations are done on this cylinder. Its the same for every propeller (heli or airplane).

I said "problem" because every game does it this way.

 

It could by fixed by changing the cylinder size based on the propeller pitch, but honestly, I think the development time required is better spent elsewhere.

[KLR Rico]

Huh? I can change the RPM setting on the engine and watch the propeller's apparent "thickness" change in real time in the external view.

 

The helicopter rotors also visibly change in response to collective or TR pitch.

 

The only problem I can see with the P-51 is that it's mapped like the RPM lever adjusts blade pitch directly instead of pitch being set by the govenor, as it should be.

 

But yes, it's a *very* minor point and development time is better spent elsewhere.

[winz]

Oh, sorry then. Haven't noticed the thickness change myself.

[BitMaster]

Havent noticed that flaw yet, I guess I finally should commit to glasses :geek:

 

 

I have to say, I haven't read all of the posts in this thread and I have not looked once on the drawing but I ask myself if the pitch really does what I think it should, though I might be wrong with what I expect. Is it right to assume that this is true:

 

When on landing approach and RPM high and throttle low the pitch should be low/flat and act like a brake disk. Allowing me to use the prop as brake instead of a pure windmill or even worse, accelerator. ( = acting like a car in 2rd gear and passive high rpm downhill, motor brake )

 

 

When taking off and RPM high and throttle high the pitch should also be on the lower end to provide a more torque at low speed and increase in pitch as you increase air speed. With same setting but high air speed the pitch should be at the high pitch end of travel to provide torque

at high airspeeds.

 

It would, as a result of my theory, be not that good to lower rpm on approach and also cut the power as the propeller would be forced to go into a high pitch condition to have less drag.

In theory, it could be that up to a certain MP it would actually slow you down more instead of accelerating ?? Could that be true ?

 

 

Just asking myself of how much misuse could be done to it and what would happen in each situation, given that the only constant we have is the RPM we dial in.

 

I would rather prefer a manual Pitch lever sometimes but there are so many drawbacks on that one that I hope it actually does in the sim as I described above.

 

Bit

[KLR Rico]

When on landing approach and RPM high and throttle low the pitch should be low/flat and act like a brake disk. Allowing me to use the prop as brake instead of a pure windmill or even worse, accelerator.

 

Yes. In fact, I've been told that a windmilling propeller is capable of producing the same amount of drag as a solid disk of the same diameter. Some props have a negative torque system that senses when the propeller starts to drive the engine and increases blade pitch to reduce the negative torque. I'm not sure if the P-51 had such a system or if there was another mechanism they used to solve that issue, it certainly doesn't seem to be excessively draggy in windmill. It could be that the Merlin doesn't have very high engine braking potential and it doesn't take much negative torque to make the engine gain RPM to satisfy the govenor. In contrast the T-56 turboprop engine *can* sink a ton of power, it takes 7000 HP to drive the compressor at 100% RPM, so a negative torque system is very important there.

 

When taking off and RPM high and throttle high the pitch should also be on the lower end to provide a more torque at low speed and increase in pitch as you increase air speed. With same setting but high air speed the pitch should be at the high pitch end of travel to provide torque

at high airspeeds.

 

Yes and no. An increase in engine MP means an increase in torque applied to the propeller. The increase in torque would have made the propeller speed up, except the govenor senses the increased RPM and increases the blade pitch to reduce the RPM until everything is in balance again. The end result is that torque is converted into thrust, and RPM remains constant.

 

The particular blade pitch that is needed to balance the RPM to the torque varies with conditions, but yes, the blade angle will be closer to feather during high speed cruise than during takeoff.

 

 

It would, as a result of my theory, be not that good to lower rpm on approach and also cut the power as the propeller would be forced to go into a high pitch condition to have less drag.

In theory, it could be that up to a certain MP it would actually slow you down more instead of accelerating ?? Could that be true ?

 

To create the most drag from the propeller for braking you'd want the lowest MP and the highest RPM to try and get the propeller to drive the engine. In that situation, the propeller will decrease pitch to try and keep the RPM up, but as soon as you bring the engine power back up, it'll just readjust the blade pitch and you'll be making thrust again.

[cichlidfan]

After watching drawings and diagrams of how usual Hamilton Standard prop works, I think I understand what Effte was after and I admit I was wrong.

 

One of the differences between an amateur and a professional is that the latter knows he or she will at times be wrong, and is prepared to admit it once thoroughly (and, usually, repeatedly) convinced of the fact.

 

I promise I will do the same in the unlikely event that it ever happens. ;)

 

Rep inbound! Edit: Er, no. It says I can't. You'll have to get by on the warm, fuzzy feeling of the intention!

 

@ effte

 

I repped him on your behalf! :)