BMW 801 Throttle Response

[Fauster]

Anyone else notice the 190's engine takes a good while to rev back up after dropping power? It's pretty detrimental when trying regain speed after cutting throttle for overshoots, scissors, and such.

 

Is there a legitimate reason this occurs? I'd imagine it's the Komandogerat possibly slowing things down, but I'm curious if anyone has any factual documentation in regards to this.

[GridiroN]

Nope...

 

The few time I tried to use manual RPM because some people said it gave better performance, the propellor changed RPM too quickly for me to monitor in combat.

[JV69badatflyski]

Anyone else notice the 190's engine takes a good while to rev back up after dropping power? It's pretty detrimental when trying regain speed after cutting throttle for overshoots, scissors, and such.

 

Is there a legitimate reason this occurs? I'd imagine it's the Komandogerat possibly slowing things down, but I'm curious if anyone has any factual documentation in regards to this.

Yes, there is a full report here:

https://ntrs.nasa.gov/search.jsp?R=19930093290

 

Kr

[=TBAS=Sshadow14]

when i read in a test like that

"fluid was kept at room temperature so it was approx the same as it would be in the engine bay"

thats not very accurate when the tester say approx

[Irgendjemand]

I experienced the issue quite often. If you ran full power and then throttle down it sometimes takes ages to throttle up again and remains idle for what felt like 5-10 seconds.
The effect of this can be devastating when in aircombat.
Just another little tripwire if you ask me.

[Dakpilot]

Okay I will ask you

 

Do you seriously think the dev's have cunningly designed in an intentional 'tripwire' on the FW-190 where the throttle is unresponsive for 10 seconds?

 

Cheers Dakpilot

[9./JG27DefaultFace]

Isn't this just the auto prop pitch adjusting to reduce drag, and then having to spool all the way back up when you add power again? Does the same in the 109, especially noticeable in DCS. Just fly manual or bind a button to switch it off for a few seconds before you pull power out.

[Irgendjemand]

Okay I will ask you

 

Do you seriously think the dev's have cunningly designed in an intentional 'tripwire' on the FW-190 where the throttle is unresponsive for 10 seconds?

 

Cheers Dakpilot

 

all I am saying is that i dont think that being unable to rev up for a signifcant amount of time during combat is how the engineers imagined this to work.

[Fauster]

That's some great stuff Badatflyski. I'll have to give it a read. 

 

Irgendjemand, if the engine characteristics in game are false I doubt it's any sort of "tripwire" and rather some form of bug. After all the Hs129 likes to shut its mixture to 0 if you don't tap it before engine start so things like this are always possible without bad intentions. Though I understand your frustration trust me.

[JtD]

DefaultFace has already nailed it.

 

Comparing the Kommandogerät regulated engine with a simple constant speed prop (CSP) engine gives you a major difference in how prop pitch is being handled at low power settings.

 

The CSP will try to maintain the rpm set with the rpm selector, for this, upon throttle, it reduces pitch until either selected rpm are being reached or until the minimum pitch setting possible has been reached. With throttle set to idle, typically the latter is the case, because by windmilling alone, selected rpm are hard to reach. Consequently, as you power up, the engine will spool up against no resistance except engine inertia, still assisted by windmilling, until selected rpm have been reached. Only then the CSP will start to increase propeller pitch in order to not exceed permissible rpm. Historically, this could be problematic, as the pitch adjustment would need some time, and slamming the throttle forward could cause engine damage due to over-revving. You'll also not receive any thrust until the prop starts adjusting, which however typically is very soon.

 

The Kommandogerät works differently, because it also controls rpm. As a consequence, in particular at idle, selected rpm are very low, and in order to not exceed them, the propeller will increase pitch a lot, sometimes to the point where the idling engine still has to work against the airflow - no windmilling here. The prop therefore is in the extreme opposite corner when compared to a CSP. So when you now apply power, the prop will immediately have to adjust (lower pitch) and the engine will not only need to overcome inertia, but with high pitch settings, also work against the airflow, and quite a bit for that matter. As pitch is fairly slow to change, it takes a while for the engine to spool up. Good news is you'll immediately gain thrust, bad news is, it's not a lot, because the engine is far from full power. You'll also not over-rev your engine, which allows quick adjustments to power settings.

 

What you can do is to switch to manual at some point, or to not reduce the throttle to fully idle. Keeping the engine at 1500 rpm or so should avoid most of the trouble.

[Fauster]

JtD that makes sense and is what I expected but is there any reason why the 109 (which I'm assuming uses a similar system) has a much better response?

[9./JG27DefaultFace]

The system in the 109 is much simpler than the Kommandogerät in the 190. I think it controls the engine based only on or 2 parameters whereas the 190 has more or less an old school computer.

 

Like I said in DCS the effect is very noticeable, not sure why it is less so here. Maybe the broader blades on the K4 than the G2 and F4 make a big difference there. Not sure how the 190 compares as far as chord length in the prop blades though.

 

Still it’s quite easy to fly manual prop pitch in bos which avoids the problem altogether.

[Irgendjemand]

Thanks for clarifying the issue. When I get to fly again i will definately use your advice.
 

[Bremspropeller]

On ‎12‎/‎31‎/‎2017 at 5:55 PM, 9./JG27DefaultFace said:

The system in the 109 is much simpler than the Kommandogerät in the 190. I think it controls the engine based only on or 2 parameters whereas the 190 has more or less an old school computer.

 

Like I said in DCS the effect is very noticeable, not sure why it is less so here. Maybe the broader blades on the K4 than the G2 and F4 make a big difference there. Not sure how the 190 compares as far as chord length in the prop blades though.

 

Still it’s quite easy to fly manual prop pitch in bos which avoids the problem altogether.

 

The workaround is just that: A workaround.

 

I'd suggest you try to work with the intended way the engine works, because you'll need to anticipate the airplane's speed-trend and act in advance, instead of just hot-cooking the throttles like you could do in other airplanes with a more direct link between power-Lever and power/ thrust.

It's good practice to learn this (especially when flying jets without speedbrakes *cough* Me 262 *cough* is around the corner).

 

The great thing about the IL-2 game-family is that you can actually take away a couple of things into real-world flying (should you ever do it anyway). One of that is the throttle-response of the 190 and the need to anticipate the aircraft's reaction to a greater deal than in airplanes where power and thrust are instantly available at lower RPMs.

 

What also works is leaving the engine at a higher power-setting and side-slipping your airspeed away. That's not the most elegant solution, but again, it might come handy some time.

Having too many handling-skills has never killed anyone. ?

 

Another good thing to practise would be "flying by the numbers" - establishing an RPM/ ata combination that would give you approach-speed and a stable (not too steep) descend in approach-configuration (gear down, flaps fully set).

That would be the way how you're flying in the real world and it Looks somewhat like this:

In a C172, Flaps 10 and 1700RPM gives you a steady 500fpm descent at a trimmed 90KIAS.

You'd use that mainly for instrument approaches, but knowing this is great under normal conditions too, as you can let the airplane fly on it's own (with minimal corrections), while keeping an eye out for traffic, handling the radios, etc.
 

[9./JG27DefaultFace]

Not really sure what you're on about but workaround or not, flying manual prop pitch gives a significant performance boost  in dogfights in BOS. At least in the 109 it does. I don't fly that much 190 but I'm sure it doesn't hurt.