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Late Mercedes D.III Engines for Albatros D.Va and Fokker D.VII


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Right now the Fokker D.VII runs on the 1914 Prototype 160hp Engine with 4.5 Compression and the Alby runs the 1917 Model 4.64 Compression with 180hp. 

By 1918 the 5.73 Compression, Domed Iron Piston Engine with 200hp was the main produced Engine, and the 217hp Model with domed Aluminium Pistons was uncommon but available as well.

 

The Halberstadt already has the 1917 and 1918 Engines, so why not the Fokker and Alby?

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Technically the “vanilla” D.VII in RoF/FC has the 180hp Mercedes D.IIIa, not the 160hp Mercedes D.III which it had at Adlershof in January 1918. Likewise the Albatros D.Va in RoF/FC has the 180hp Mercedes D.IIIa, not the “200hp” Mercedes D.IIIaü it had at Adlershof either.

 

Why?

 

Mmmh... I remember an old dev quote from the original neoQB about these planes being developed as hybrids. I could go dig around for it but everything pre-2011 on the RoF forum is a mess. If these planes were developed today they’d have several engine variants like the Halberstadt CL.II (180/200hp) and Albatros D.II do (includes an earlier radiator design), both of which were developed a bit later.

 

Will they ever add engine variants?

 

I suppose it’s a matter of time, money and interest.

 

 

 

EDIT: Found one of the OG Albatros D.Va and Fokker D.VII performance threads, including dev response: https://riseofflight.com/forum/topic/3203-albatros-dva-performance/page-1


The thread I was looking for (“hybrid” was not a dev quote): https://riseofflight.com/forum/topic/11038-current-rof-airplanes-flight-model-discussion-topic/page-2

The information about the D.III(a/ü) test by the British provided by @MiG-77 is especially interesting.

Edited by J5_Hellbender
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  • 2 weeks later...

Its not just straight porting over here with better textures. The flight model does indeed feel different in FC as compared to RoF. For example, I noticed the SPADXIII in FC felt alot like a SPAD VII in RoF when I first made the transition from RoF to FC. Others might be able to comment on other planes.

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14 minutes ago, US213_Talbot said:

Its not just straight porting over here with better textures. The flight model does indeed feel different in FC as compared to RoF. For example, I noticed the SPADXIII in FC felt alot like a SPAD VII in RoF when I first made the transition from RoF to FC. Others might be able to comment on other planes.

I think a lot of impressions we get in these Sims are also very much down to FPS and FM Calculations per Frame.

Often Hardcore Simmers will complain about how FMs may have been simplified after a Patch, while all that happened was a Performance increase leading to more responsive/easier feel.

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If there’s a question to be asked, about the D IIIa engine, or even the BMW engine for that matter, it’s why they produce their full power, if not more, when doing a static load test ?

 

By comparison, the Viper engine reaches a believable 80% of it’s (notional) power during a static load test although, unlike the Central inline engines, it doesn’t reduce further when taking off.  Which makes me think, I have to go and check to see what rpm they can manage at the top of a stall turn.

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On 1/17/2021 at 12:52 AM, HagarTheHorrible said:

If there’s a question to be asked, about the D IIIa engine, or even the BMW engine for that matter, it’s why they produce their full power, if not more, when doing a static load test ?

 

By comparison, the Viper engine reaches a believable 80% of it’s (notional) power during a static load test although, unlike the Central inline engines, it doesn’t reduce further when taking off.  Which makes me think, I have to go and check to see what rpm they can manage at the top of a stall turn.

 

Instinctively I would say the Propellers. From what feels like the D.VII has very Coarse Pitch and thus Blade Stall or Blade Slip when Static. So it essentially converts a lot of Power into Turbulence instead of Thrust, which offers far less Resistance, meaning the Engine Revs higher, just like a Stalled Wing produces less Lift despite higher Angle of Attack. 

 

A Proof of this is that the Engine Slows on initial Acceleration during Take Off.

 

This is a Real World Effect. Google the Everell Single Blade Propeller.

https://www.aopa.org/news-and-media/all-news/2018/november/pilot/singular-sensation

 

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9 minutes ago, 6./ZG26_Klaus_Mann said:

From what feels like the D.VII has very Coarse Pitch

It is not that coarse.

 

Early Fokker D.VII with ethe 160 hp Mercedes had the Axial prop with a pitch of 2.05 m and later on the 200 hp BMW engine got a steeper prop with 2.12 m pitch. The first one is also consistent with what the Swiss used on their Fokker D.VII that they bought in 1918. They got the 160 hp Mercedes and that is what we have in the museum now.

 

The 160 hp Mercedes D.III variant can go about 170 km/h  and the BMW engine gives it about 180 km/h. This at 1400 rpm each. This is pretty standard and I'd say and still more of a climb prop than a cruise prop. Propellers for rotary engines are steeper, as rotaries crank at about 15% less rpm, but it is the same class. If the blades are stalled out on a ground rung, then by all means they should do so on the Oberursel powered aircraft. But they don't, achievable ground runs are well below cruise rpm.

 

In game, our Fokker D.VII has the Axial D2.8/P2.05, as it almost does something like 170 km/h @1400 rpm. The engine cranks high though, up to1560 rpm. This means, if nominal power of 160 hp is produced at 1400 or so rpm, then craking up to 1560 rpm gives me about 180 hp (as stated in the spec sheet of the game) and a top speed of 186 km/h (or so). The in game D.VII is very much spot on specs.

 

If we ever get an Mercedes D.IIIaü for the Fokker D.VII you get better climb, better sustained turn (just a little, but better) and the same level speed. For anything else you have to find a different propeller. I know of the two I posted above. Anyone knows more variety, please share.

 

To get more speed, we would need the Mercedes D.IIIavü that cranks up to 1600 rpm. This would increase level speed accordingly.

 

The in game D.VIIF is a bit more odd, as it does 187 km/h @1400 rpm.  This makes it something like a 2.25 m pitch prop. I have never heard of such a propeller on a D.VIIF. In consequence, the D.VIIF is about ~5% too fast regarding the rpm and it goes187 km/h at 1400 rpm, which is near the end of the regular throttle travel. Opening the throttle fully by use of Höhengas, this can crank the power up to 1520 rpm. If we have 230 hp at 1400 rpm, then those 1520 rpm give the stated 250 or so hp stated in the spec sheet. This is all fine and consistent, but the crate is ~5% too fast level speed. (Not that I care too much about that in our game. But if there is work done on the WW1 crates, one might make them right.)

 

 

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