Climbrates of german planes

[Matthias]

Hi guys, it's my first post here. I'm Matthias (call me Matt), 25 years old and from northern Germany and a WWI aviation enthusiast like you. Definately the best forum around about information on WWI aviation, i've been reading through a various of threads for a few months now.

I have some climbrates of some german planes, that i find suspect and would like an opinion about this. I don' really want to "reveal", where i got these, let's just say they are from a certain WWI flight simulation (wish i had the real planes around instead, but what can i do...).


Fokker DVII with DIIIa engine (i know that it shouldn't have this engine). These are the climb times:

1000 m — 3 min. 38 sec.
2000 m — 7 min. 40 sec.
3000 m — 12 min. 53 sec.
4000 m — 20 min. 19 sec.
5000 m — 33 min. 50 sec.


Pfalz DIIIa with DIIIa engine.

1000 m — 3 min. 50 sec.
2000 m — 7 min. 55 sec.
3000 m — 12 min. 51 sec.
4000 m — 19 min. 19 sec.
5000 m — 28 min. 38 sec.


I can't really make any sense out of it. Why would a DVII be a faster climber until 2000 meters and then suddenly a Pfalz DIIIa is able to climb a lot faster. With the same engine. Would like to hear some comments from you guys, because you know a lot more about this then i do. Would you consider any of these two climb tables realistic? If so, with what engine (if the engine noted above would be incorrect).

Thanks alot for taking your time on reading my topic and answering my question.

Regards
Matt

[HoHun]

Moin Matthias,

>I can't really make any sense out of it. Why would a DVII be a faster climber until 2000 meters and then suddenly a Pfalz DIIIa is able to climb a lot faster.

Looks suspicious for sure, but can you rule out experimental error? From my own experience in test-flying simulator aircraft (mostly "Air Warrior" and "Warbirds"), you really have to fly the tests personally to be sure they were done with a consistent method.

One factor that might have considerable influence on rate of climb would be airspeed. The two types might have different speeds of best climb rate, and depending on the wing loading (which I haven't checked), they might also show a different rate of change in best climb speed with altitude.

The climbrate-over-airspeed curve fortunately has a fairly wide maximum so that it isn't so difficult to stay close to the optimum speed, but any deviation will be more telling with decreasing climb rates, and from your data it looks as if the difference is the greatest at high altitude, so this seems to be a factor worth looking into.

(In addition to having different true airspeeds of best climb, there is also the possibility that the speed indicators are calibrated differently - I have seen that with some "Warbirds" aircraft.)

I hope these initial comments are of some use to you ... there's even more depth to the topic, of course! :-)

Regards,

Henning (HoHun)

[Oesau]

I know exactly which sim is being referenced here

There are a number of issues with the Pfalz D.IIIa IMO and this is only one of them. I haven't had the time to start collecting the information so happy that you are.

As been mentioned, the climbing stats used in this sim don't always line up with historical records (and how accurate are they) as there is a difference in testing of the climb times (such as the climb to height is being referenced in the sim from a standing start - I am not sure the other records are from a standing start or from a stabilized climb speed at near to sea level and then hold the climb).

[Matthias]

Thanks alot for answering guys.

@Hohu:
I can't really get any info for the sources which the flightmodel designers based these climb-times on. I'm pretty sure they are just confused with the different engine types of the DIII engine mostly. This is indeed very confusing (difference DIIIa <-> DIIIau etc.), but a Pfalz DIIIa outperforming a DVII with the same engine just doesn't work imo. But maybe i'm wrong, if so, please let me know guys.


@Oesau:
Well, i though i was not the only one here, who likes that flightsim. Dispite most of the obvious flightmodel flaws, this is pretty much as realistic as it can get for now. That's why i would like to convince the (very stubborn...) game designers to improve the flightmodels.

I agree also that there are more things wrong with the Pfalz DIIIa. It can basically outmanouver a Fokker DVII with ease, aswell as all other inline-engine planes that have been added to the sim so far. It can roll very fast, can fly a very tight circle, rarely stalls or gets into a spin. While the DVII actually rolls extremely slowly (while it was one of the best "rollers" of its time). But i guess this is too much to discuss on this topic here.

[Oesau]

Well if it helps, I'm in the beta team and can present facts and figures to them off the main forums (and happy to do so).

[HoHun]

Moin Matthias,

>I can't really get any info for the sources which the flightmodel designers based these climb-times on.

Slight misunderstanding: I wasn't talking about real-life tests, but about tests of the simulated aircraft.

You're right that the data you quoted looks suspicious, but is the data you quoted the result of accurate flight testing of the simulated aircraft?

In my experience, the only way to be sure is to come up with a working methodology and do the testing personally.

That may be just what you did, but you didn't mention so far :-)

Regards,

Henning (HoHun)

[Matthias]

@Oesau: Are you one of the "bright red" beta testers or one of the "dark red"? I have a few beta testers of the latter type in my virtual squadron.

The problem is, for manouverability etc., you can't really present them any hard facts or sources. Second problem is, that even if you provide data for climb time etc., they rarely react and really take these sources into consideration.

@HoHun: We made some tests in our forum and came up with these times for the DIIIa and DVII.


DIIIa
1000 m — 3 min. 25 sec.
2000 m — 7 min. 25 sec.
3000 m — 12 min. 30 sec.

DVII
1000 m — 3 min. 10 sec.
2000 m — 7 min. 26 sec.
3000 m — 12 min. 37 sec.

These times are a bit off compared to the earlier figures, but still very close (we didn't count the take-off time, if you would add that, you would probably get the same times). And the DIIIa does climb faster then the DVII in our tests, so the question remains if this should be the case, if both planes use the same engine.

[Catfish]

Hello,
funny to find all those here again, but also no big surprise lol.

While the flying as such is best modelled in RoF (especially thinking of landing those taildraggers, and then especially the N17), i still think that the exact numbers of climb speeds and ceilings are represented best in the Over Flanders Fields (OFF) WW1 sim.

I also wonder why they put this BMW engine in the Pfalz D.XII, if there were only 20 of those equipped and operational, at all. I also find the flight behaviour and capability of the D.XII much bader, than before.

Greetings,
Catfish

[HoHun]

Hi Matthias,

>And the DIIIa does climb faster then the DVII in our tests, so the question remains if this should be the case, if both planes use the same engine.

From a couple of quick assumptions, I have calculated climb rate for the D.VII and the D.IIIa with a constant-speed propeller.

Of course, they don't really have one of these, but assuming both aircraft have the same engine and propeller, this doesn't change the relative performance.

The attached graph shows my results.

Regards,

Henning (HoHun)

[Matthias]

Hello,
funny to find all those here again, but also no big surprise lol.

Hi Catfish.

Well no big surprise really, as the official forums of ROF are crowded with people who don't seem to have any idea about this at all. Makes no sense to discuss something like this here.

@Hohun
What program (or formula) do you use to calculate something like that? Could come in handy.

Also wouldn't drag, wing profile etc. have an influence on climb performance aswell?