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Mercedes D.IIIaü for Albatros D.Va and Fokker D.VII (instead of D.IIIa)


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#41 ZachariasX

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Posted 07 February 2016 - 23:42

These are not really suitable comparisons. Increasing 'lb' gives you a different engine. New fuels allow you to +lb'


Ah, can't edit. If you don't let the super/turbocharger to turn faster, both fuels (low/high octane) will give you about same results as long as low octane is permissible.
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#42 ZachariasX

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Posted 07 February 2016 - 23:44

Modelling a carburation weakness would only cause unnecessary confusion. When some learners don't understand why their plane veers to the right or left on takeoff, the last thing they need is an engine that dies at full throttle.


Another clear case of RTFM ;)
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#43 Dressedwings

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Posted 07 February 2016 - 23:47

Increasing 'lb' does not change the engine, for most cases it was just adding stronger parts.

 

It says so on the source I posted.

 

I don't fully understand what you mean though.


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TOeIhAe.png

^CHECK THE LINK^


#44 J2_Adam

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Posted 08 February 2016 - 00:30

True but personally I don't really care about the steam downloader gamer types who can't start their SPAD because they didn't pay attention in shop class
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#45 FitzD7

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Posted 08 February 2016 - 00:51

Yes. In regards to the real DIIIau,  Mikael Carlson said that the throttle on his DVII with the Merc DIIIau never goes to full throttle. In fact he has installed a stop to prevent it from doing so. He said that if he were to remove the stop and he were to use full throttle at take off or low altitude the engine would just simply quit due to being to lean of a mixture. 777 got this stuff slightly wrong.

I wonder if Mikael Carlson is/has rejetted his carbs to compensate/adjust to today's gas or avgas?

 

I'd like to hear from him.


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#46 J2_Adam

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Posted 08 February 2016 - 01:15

I doubt it. He seems like pretty much a purist. I don't don't know and I'd be curious too
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#47 FitzD7

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Posted 08 February 2016 - 01:31

I doubt it. He seems like pretty much a purist. I don't don't know and I'd be curious too

You can die being a purist. The fact that he's blocked the throttle to prevent WOT tells me he's amenable to other subtle changes.

 

I'm sure he's made other changes to accomidate today's fuel.

 

If he enriched the carbs power enrichment stages, assuming those carbs have them, that would seem sensible. Then he could go WOT if he had to.

 

But perhaps those carbs are too rudimentary to allow changes like that, and I'm speaking in automotive terms, which is all I know.


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#48 J2_Adam

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Posted 08 February 2016 - 02:11

He never flies it about probably above 3000'. So to avoid running into any sort of trouble, he opted for safety.... Run in an over lean situation and run the risk of screwing your Mercedes DIIIau. I think for the most part he'd be a purist. His DR1 is one of the most accurate reproductions in the world for example
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#49 ZachariasX

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Posted 08 February 2016 - 08:43

Increasing 'lb' does not change the engine, for most cases it was just adding stronger parts.

 

It says so on the source I posted.

 

I don't fully understand what you mean though.

 

Sorry for not having been clear. What is the threshold of an engine being "different" we hardly need to discuss as this is often of an arbitrary nature.

 

The point of the discussion was, that if you have an (old) aspirated engine, designed to run on low octane fuel, and you supply it with high-octane fuel, it would not give you extra power when operated in the same regime.

 

The examples you provided, where changes on the supercharger were made possible due to the octane rating, is a different thing. Merlins etc. are high performance supercharged engines that are mainly limited in their power output through pre-detonating fuel air mixture when compression gets excessive. In those engines, fuel quality is one parameter that allows you to generate more power by either just let the engine run at higher rpm (if the engine block tolerates that) and in consequence have increased boost by the same blower, or adjust fan and/or gearing of the blower to get higher compression (more air) at the same rpm. Most Merlin variants exist because of the latter modifications.

 

In all cases with the engines you mentioned, you run the engine in a different regime than with the lesser grade fuel in order to get more power. If you call that a new engine or not, this decision I leave to you.

 

Z


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