When will the power issue be complete?

[fastfed]

Im afraid they think this place is adequate when it comes to its performance. I remember first jumping into my favorite ww2 plane in DCS and thinking something is way off here, this thing barley does over 200 mph, even stripped down with no fuel..

 

Then we all saw what we thought was just a binding issue, you can actually get more rpm from it and the plane actually moved, and like real life was one of the fastest planes for its time. now it seems it was just a bug and the max rpm is 2700 and we are back to what is supposed to be one of the fastest planes to the slowest. Its really annoying. 

 

With frustration I stopped flying it and just jumped back in yesterday, now if you give it to much power, over 50 manifold, the engine starts knocking and will die quickly.. And with that, this plane is a joke, struggles getting over 20k feet, when carrying payload it struggles flying in general. it needs more power, something is seriously wrong 

[GTFreeFlyer]

4 hours ago, fastfed said:

Im afraid they think this place is adequate when it comes to its performance. I remember first jumping into my favorite ww2 plane in DCS and thinking something is way off here, this thing barley does over 200 mph, even stripped down with no fuel..

 

Then we all saw what we thought was just a binding issue, you can actually get more rpm from it and the plane actually moved, and like real life was one of the fastest planes for its time. now it seems it was just a bug and the max rpm is 2700 and we are back to what is supposed to be one of the fastest planes to the slowest. Its really annoying. 

 

With frustration I stopped flying it and just jumped back in yesterday, now if you give it to much power, over 50 manifold, the engine starts knocking and will die quickly.. And with that, this plane is a joke, struggles getting over 20k feet, when carrying payload it struggles flying in general. it needs more power, something is seriously wrong 

It helps to understand some of the science here.  Here’s what I can offer to help appreciate the bird a little more.  If you already know this stuff, then please ignore me, but I’ll post it for those in the community who may not know it:
 

Max power does not equal max speed.  Max power refers to engine power, not the power that is converted and comes out of the prop to propel you forward.  Max engine power just eat up more fuel.  
 

If you’re running at 2700 and expecting high speed, try running a car or bicycle in 1st gear.  It’s similar.  The propellers need to take more bite out of the air when flying quickly.  So why then would the engine be putting out so much power, without a lot of speed?  Well, look up propeller advance ratios.  It’s analogous to the angle of attack of a wing’s airfoil.  When a propeller is running flat with high airspeed, you are way off the maximum efficiency point for the propeller’s airfoil.  The propeller would be doing a terrible job at converting mechanical power (equal to torque times RPM) into propulsive power (which is equal to thrust times velocity).  This is the sole purpose of a propeller: Convert the power.  If your propeller is only 20% efficient here (a reasonable number for low advance ratios caused by high RPM and not a lot of forward movement), then for every 100 HP the propeller can put out, the engine must supply 500 HP.  
 

For max speed, you want to find the point where the propeller airfoils are operating at their most efficient local angle of attack. With variable pitch props, prop efficiency can be brought up in the neighborhood of around 80% to 85%.  You’ll never get 100% because the blade will always slip a little in the air when chopping at it.  So for that same 500 HP from the engine, you now have so much more speed from the power conversion because the propeller is only wasting 20% the supplied power now, simply by changing the blade pitch, even when at a LOWER RPM, just like your car or bicycle. 
 

How do we find this optimum point where we can maximize our prop efficiency?  As pilots, we use the charts the engineers put together for us since we don’t have direct control over blade pitch, or what would be even better, the advance ratio.  As an aerospace engineer myself, I’ve spent lots of time in wind tunnels over my career with propellers collecting this data, and publishing performance charts. I love this stuff and can talk about it all day.  It’s tough to grasp at first, but if you ever want to know more, just shoot me a message.  
 

You mentioned above that you could barely get above 200 knots.  I just did a flight earlier today at 5,000 feet, cruising conservatively at 2200 RPM and around 33 MP and was moving around 210-220 kts indicated, which is around 235 knots true.  Try it out.  I could have pushed it even faster if I played around with the MP and RPM, but I was just cruising  to save fuel when flying back to the boat.  Propeller efficiency is a huge deal, and you’re not going to get good efficiency at 2700 RPM unless you are very slow, because the blades are flattened out.  Jets move faster or slower based on your throttle position. Warbirds are completely different.  Just remember that RPM control has nothing to do with setting the RPM on your engine.  The RPM lever controls a governor that is linked to blade pitch.  So, when you pull the RPM lever back, you may actually be INCREASING thrust because now your blades will start biting into the air.   
 

Yeah, I’ll agree that some things with this module need tweaking near the edge of the envelopes of altitudes, temperatures, ground handling etc, but for the most part, this plane feels pretty good, and operates very closely to the charts when flown correctly.  Not too bad for its early access, incompleted, state.

 

I uploaded a quick test mission with a script that shows you engine diagnostics.  Spend 5 minutes with it.  It’s an air start, so you can quickly start playing with different throttle and RPM settings and see their effect in real time.  It’s a great learning tool.  
 

Hope you found this helpful,

-GT-

[Scotch75]

It helps to understand some of the science here.  Here’s what I can offer to help appreciate the bird a little more.  If you already know this stuff, then please ignore me, but I’ll post it for those in the community who may not know it:
 
Max power does not equal max speed.  Max power refers to engine power, not the power that is converted and comes out of the prop to propel you forward.  Max engine power just eat up more fuel.  
 
If you’re running at 2700 and expecting high speed, try running a car or bicycle in 1st gear.  It’s similar.  The propellers need to take more bite out of the air when flying quickly.  So why then would the engine be putting out so much power, without a lot of speed?  Well, look up propeller advance ratios.  It’s analogous to the angle of attack of a wing’s airfoil.  When a propeller is running flat with high airspeed, you are way off the maximum efficiency point for the propeller’s airfoil.  The propeller would be doing a terrible job at converting mechanical power (equal to torque times RPM) into propulsive power (which is equal to thrust times velocity).  This is the sole purpose of a propeller: Convert the power.  If your propeller is only 20% efficient here (a reasonable number for low advance ratios caused by high RPM and not a lot of forward movement), then for every 100 HP the propeller can put out, the engine must supply 500 HP.  
 
For max speed, you want to find the point where the propeller airfoils are operating at their most efficient local angle of attack. With variable pitch props, prop efficiency can be brought up in the neighborhood of around 80% to 85%.  You’ll never get 100% because the blade will always slip a little in the air when chopping at it.  So for that same 500 HP from the engine, you now have so much more speed from the power conversion because the propeller is only wasting 20% the supplied power now, simply by changing the blade pitch, even when at a LOWER RPM, just like your car or bicycle. 
 
How do we find this optimum point where we can maximize our prop efficiency?  As pilots, we use the charts the engineers put together for us since we don’t have direct control over blade pitch, or what would be even better, the advance ratio.  As an aerospace engineer myself, I’ve spent lots of time in wind tunnels over my career with propellers collecting this data, and publishing performance charts. I love this stuff and can talk about it all day.  It’s tough to grasp at first, but if you ever want to know more, just shoot me a message.  
 
You mentioned above that you could barely get above 200 knots.  I just did a flight earlier today at 5,000 feet, cruising conservatively at 2200 RPM and around 33 MP and was moving around 210-220 kts indicated, which is around 235 knots true.  Try it out.  I could have pushed it even faster if I played around with the MP and RPM, but I was just cruising  to save fuel when flying back to the boat.  Propeller efficiency is a huge deal, and you’re not going to get good efficiency at 2700 RPM unless you are very slow, because the blades are flattened out.  Jets move faster or slower based on your throttle position. Warbirds are completely different.  Just remember that RPM control has nothing to do with setting the RPM on your engine.  The RPM lever controls a governor that is linked to blade pitch.  So, when you pull the RPM lever back, you may actually be INCREASING thrust because now your blades will start biting into the air.   
 
Yeah, I’ll agree that some things with this module need tweaking near the edge of the envelopes of altitudes, temperatures, ground handling etc, but for the most part, this plane feels pretty good, and operates very closely to the charts when flown correctly.  Not too bad for its early access, incompleted, state.
 
I uploaded a quick test mission with a script that shows you engine diagnostics.  Spend 5 minutes with it.  It’s an air start, so you can quickly start playing with different throttle and RPM settings and see their effect in real time.  It’s a great learning tool.  
 
Hope you found this helpful,
-GT-

Great post GT, this helped me understand constant speed props more. Also, we tend to forget that the massive propeller (13ft diameter IIRC) has a mass that has to be moved by the engine, so you lose some HP there.
I would like to know what settings were used for combat when you are constantly changing throttle quite abruptly at times. I assume the engineers come up with max continuous as a balancing point of not overloading the engine, not overspending the prop, preventing knocking, and providing enough thrust for combat manoeuvring. Included in this is the pilot not having to spend brain power on thinking of all of this in a dogfight.
Cheers!


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[GTFreeFlyer]

33 minutes ago, Scotch75 said:

Great post GT, this helped me understand constant speed props more. Also, we tend to forget that the massive propeller (13ft diameter IIRC) has a mass that has to be moved by the engine, so you lose some HP there.
I would like to know what settings were used for combat when you are constantly changing throttle quite abruptly at times. I assume the engineers come up with max continuous as a balancing point of not overloading the engine, not overspending the prop, preventing knocking, and providing enough thrust for combat manoeuvring. Included in this is the pilot not having to spend brain power on thinking of all of this in a dogfight.
Cheers!


Sent from my SM-G998B using Tapatalk
 

Thanks!  Glad to help.  The mass of the prop will only really eat up some power if you are constantly accelerating/decelerating it.  As for your question:

I'll refrain from trying to answer this one because I only have limited IRL combat experience (banging head on keyboard, punching fist thru monitor, smashing printers in an open field , etc), and prefer not to give any incorrect info.

In DCS, I try not to change throttle much at all, even in combat.  Try to manage your energy.  Come in for a high speed dive, take your shots, zoom on by and regain the energy up high for the next pass, ideally without touching my throttle or RPM.  If things get complicated with the bandit and I'm in a bind, I'll push it up to 2700 RPM only when slow on speed and I need to accelerate quickly, then I'll pull RPM down a little again to keep some speed and not run in first gear too much.  Is it the correct way?  I dunno.  I'm always learning.  It works for me, but then again, I also get shot up a lot I'm much more comfortable with the engineering stuff over combat

 

[Scotch75]

Thanks!  Glad to help.  The mass of the prop will only really eat up some power if you are constantly accelerating/decelerating it.  As for your question:
I'll refrain from trying to answer this one because I only have limited IRL combat experience (banging head on keyboard, punching fist thru monitor, smashing printers in an open field , etc), and prefer not to give any incorrect info.
In DCS, I try not to change throttle much at all, even in combat.  Try to manage your energy.  Come in for a high speed dive, take your shots, zoom on by and regain the energy up high for the next pass, ideally without touching my throttle or RPM.  If things get complicated with the bandit and I'm in a bind, I'll push it up to 2700 RPM only when slow on speed and I need to accelerate quickly, then I'll pull RPM down a little again to keep some speed and not run in first gear too much.  Is it the correct way?  I dunno.  I'm always learning.  It works for me, but then again, I also get shot up a lot I'm much more comfortable with the engineering stuff over combat
 

I know how you feel. I'll certainly give your advice a shot. It makes me appreciate even more these young fellas who had to do all of this in combat and survive.
Cheers!


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