Focke Wulf Fw200-A Condor

Hello Ivan,
You mean it would be too much in one go and be off-putting... but I bet we would laugh about it over a couple of beers!

Some years ago it would have been worse, and we´d have to send each other disquettes by post. I remember the time when a Spectrum user´s club in England would post a disquette every so often, and an Amiga club later in the early 90´s, where I´d also send them back some things programmed in 3D-AMOS Basic.

Yesterday I would have actually been quite happy leaving the prop at its 7 ft. diameter, but after your answers it has piqued my curiosity again...

Well, today I have my busy Thursday, but I hope to get some time notwithstanding, at least to gather the list of information.

I´ll just put the Condor together then, and e-mail it to you - without the AFX (at least for the moment...).
Thank you very much again for your offer of looking at/into it.

Cheers,
Aleatorylamp
 
The comprehensive list of collected data:

Hello Ivan,
I´ve had enough time (just about) to do my homework:

Prop advance ratios, as per RPM, Hp, Thrust and speed

For max. Speed at S.L.Takeoff:
15.0, 2024 RPM 228 hp _869 thrust 44 mph
25.0, 2028 RPM 505 hp 1299 thrust 88 mph
31.2, 2025 RPM 719 hp 1405 thrust 128 mph
33.0, 2026 RPM 721 hp 1231 thrust 169.2 mph
34.5, 2025 RPM 720 hp 1231 thrust 196.2 mph

For max. speed at different Altitudes:
_300 ft : 36.1, 2025 rpm, 720 hp,1010 thr, 226.8 mph
5000 ft : 38.7, 2024 rpm, 751 hp, 978 thr, 240.2 mph
5900 ft : 39.2, 2024 rpm, 756 hp, 972 thr, 242.9 mph
7000 ft : 39.2, 2024 rpm, 726 hp, 934 thr, 243.0 mph
8000 ft : 39.1, 2024 rpm, 701 hp, 904 thr, 242.5 mph
9800 ft : 38.9, 2024 rpm, 654 hp, 848 thr, 241.8 mph
12500 ft: 38.5, 2024 rpm, 583 hp, 760 thr, 240.6 mph
15000 ft: 38.2, 2024 rpm, 524 hp, 689 thr, 239.1 mph
19000 ft: 37.5, 2024 rpm, 439 hp, 587 thr, 235.0 mph

...and one cruise speed. Should more be required, they will be done!
300 ft Cruise: 31.2, 2024 rpm, 480 hp, 774 thrust, 201.2 mph

With this cool-looking list, I bet there´s going to be an equally cool-looking list of formulae to be applied, but, before I can think any further, I need some more tea, and some other "thangs" have to get done this afternoon.
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Sorry to disappoint you, but the cool looking set of formulas is not as well organised as you might expect.
In fact, it is quite messy and not all that well defined. That was what I meant by "If you see it, you may be less than impressed".
I would expect a bunch of questions like
"Why did you do that?"
followed by a
"Because I think it will work"
"Why do you think that would work?"
"I am not entirely certain, but that number looks like it is too high....."

I was about to ask you for target performance, but I see that you included a pretty complete list of specifications with the Condor package.
My technicians will attempt to open up the huge crate (Zip File)
and see if they can assemble the pieces and install test instrumentation.

The obvious question with what I can see thus far is:
Why is the RPM numbers in your tests so low? The specification calls for 2050 RPM, but your test cases show 2025 RPM.

- Ivan.
 
Hello Ivan,
Thank your technicians for their efforts. Hopefully they won´t get
too upset about being landed with this Easter Egg.
Don´t worry about what I will think of their ways and means - I quite
trust and respect their methodical "empirical intuition", as it were!

As regards the formulae, I put on my Wellington boots and started wading through
those indicated in the link you posted to Mr. Beckwith´s .pdf at Mudpond.
I also wore my intelligent look so as not to scare them away or make them laugh,
and for the moment, I have them quite fooled. They think I understand...
I´ve printed those out too.

With respect to the RPM question, I´m afraid there was no way I could
find to get it above 2025 RPM for the ungeared 7 ft prop at 720 Hp.
For the 2.088 gear-ratio, 10.5 ft prop it was 2046 RPM, at identical Hp.

I just checked: Wing record 404, comes from the Sample DC-3 from Abacus
Aircraft Factory 99. It seemed the most similar I could find.

You have probably already seen that the panel is basically a test panel, with the new
gauges as well as the Beckwith Gauge Stack, Smilos´s Autopilot, apart from the standard
Learjet one.

Intelligent or stupid update: (?)
I just wrote a QBasic programme to print out the advance ratio using the
formula, and I´m getting results below 1 or slightly above 1, not something like
25 or 30 or 39 as appears in the Beckwith Gauge for the Prop Advance.
But: On the graph in the .pdf, the Advance Ratio is given on the horizontal axis
underneath, in decimals below and above 1, possibly indicating the position to find
the propeller efficiency "y" position given the left.
So, the numbers given in the Beckwith gauge correspond to those in the column on the
right of the graph (15 to 65), showing which graph line to be used...
This efficiency result is what I want to discover?

If you need any more information, do let me know. Good Luck!
Cheers,
Aleatorylamp
 
Last edited:
Hello Aleatorylamp,

My Technicians have unpacked but not assembled the FW 200 for flight yet.
No idea what the panel or even the model looks like yet.
Instead, they have been looking over the Specifications Document that you included.

There might be a pretty simple solution that does not involve any butchering at all.
My lead technician suggests that you pull Record 512 from the stock Hurricane Mk.I AIR file.
It isn't an exact match, but it is quite close to the calculated numbers from your specification sheet.

My guess is that you might also need to pull Record 511 also from the stock Hurricane Mk.I AIR file,
but try just the Power Coefficient Table first and see if it gives you the results you want.
My guess is that if you swap out Table 511, the speed at altitude will drop a bit but I don't know exactly how much.

Let me know how well this works or if we need to go further with some real butchering.

- Ivan.
 
By the way, go back and look at the definitions I posted earlier.
I was trying to tell you that the numbers you were listing were not actually the Advance Ratio.
You were actually listing Propeller Pitch Angles.

- Ivan.
 
Hello Ivan,
OK, fine! Propeller pitch angles then refer to each of the graph lines ranging from 15 to 65. Of course... Thank you!
For the moment, my Qbasic program is giving me the advance ratios from which I can read the prop efficiency then...

Before that, however, I´ll see about the Hurricane propeller tables though.
You do have quite an eye for things, don´t you? That´s included in the "empirical intuition"!

I ´ll let you know how it develops!
I was actually quite looking forward to some real butchering, but maybe it´s a better idea to try something not so gory first, just in case we can save ourselves all the hassle.

OK! I´ve put in the Hurricane´s table 512, and I´m completely speechless, flabbergasted, amazed...
A quick test reveals the following maximum speeds:
>at 300 ft, 226.6 mph, just 0.2 mph lower, and Hp is exactly 720!
>at 9800 ft, 241.3 mph, only 0.5 mph slower, and Hp is the same as it was - 654 Hp!
I´ll do the rest of the tests tomorrow, but it looks like we´ve got a winner here!

How on earth could you identify this just like that?
The Hurricane engine is 1030 Hp in CFS, and higher in reality on some versions...
How would that propeller so quickly appear to be so useful?

I´ll gladly do without the butchery! Here we´ll apply the law of minimum effort...
I´ll just adjust the Oswald factor ever so slightly to get S.L. speed up by 0.2 mph!

I still can´t believe it...
I ´ll celebrate with some Sweet Sherry for desert. To your health!!

Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

Just got back from Dinner and Grocery Shopping

Regarding how I picked the Hurricane Power Coefficient Table:
You are looking at the horsepower of the engines.
I suggest that you look at the formula for Power Coefficient instead.
Power Coefficient is basically a measure of how hard the propeller is to spin.
The Hurricane runs about 50% more power but also is swinging a larger propeller and is geared which makes the propeller easier to spin.
Another interesting note is that the actual Propeller rotational speed is nearly the same between the FW 200 and the Hurricane Mk.I.
(The propeller reduction gear ratio is 1.484)
When you are doing the calculations, don't worry about the Units of Measure too much because although it changes the number you get as output, you are just comparing numbers between different aeroplanes and the UOM cancel out.

I recommend that you adjust speed by a different method than Oswald Efficency.
That value is a modifier to the induced drag and at cruise and maximum speeds, induced drag is a VERY small component of total drag.
You will probably never see this in the FW 200, but increasing Oswald Efficiency numbers will increase the speed bleed in maneuvering and also have a much greater effect at low speeds.

Instead, I would suggest the following:
Drop the Airframe Drag slightly.
This number is very granular, so the effect will be probably more than you really wanted.
THEN, note the propeller pitch angle at maximum speed at Sea Level (328 feet).
226 MPH happens to be exactly 1.0 Advance Ratio, so if you adjust the Table 511 Efficiency down at that location, you should be quite close.

The reason I would do things this way is because in general, the Propeller Efficiency in the stock CFS Tables tends to be overly optimistic in my opinion and should be adjusted downward a bit if you have a reason. The efficiency also is a very finely adjustable value.

Let me know how things work and of course, please send me an updated version.

By the way, I will have a Soda, Tea or Coffee instead of Beer.
I was just commenting that typing is a terribly slow way to communicate compared to just having a conversation, especially if we had a simulator and a couple laptop computers and the Internet to find formulas and references.

With the Ki-61-Id, I already have some pretty good performance, but need to adjust how fast the propeller gains speed on take-off.
Right now, it conflicts with a flight test report.
There are a couple other aeroplanes that are affected (such as the Type Zero Mk.II fighters, so it makes sense for me to figure out a consistent method of generating propeller tables instead of hand editing them.

- Ivan.
 
Hello Ivan,
OK, how about some green tea then?
So, the set of numbers in the bigger Hurricane engine plus prop with gearbox, serve for the Condor. A nice surprise.

Ok, I ´ll have a look and see if I can follow your instructions to get that tiny edge of an performance increase out. Sounds like a piece of cake! An interesting way to finely adjust the speed.

I´ll let you know how it goes. Thanks very much!

Update:
OK! It´s almost perfect.
I lowered Zero lift Drag by 1 AirEd unit, and then went for Prop Efficiency Table 511.
At the first try I raised Pitch angle 35 graph to 1, smoothening out the surrounding ones, but performance rose by 4 or 5 mph, which was too much. Possibly I could have increased Zero Lift Drag by another unit, but I didn´t try.

Then I cancelled the first changes and this time raised the graph only very slightly, from 0.89 to 0.91, smoothening out the surrounding ones again, and the result is almost perfect. I just have to make some even smaller adjustments to get S.L. max speed down by only 0.3 or 0.4 mph now, and then check at higher altitudes. I´ll post the .air file when I´m done.
Thank you very much again!

Update 2:
It´s very interesting to see how this propeller efficiency issue works.
So, if I´m right, for a Maximum Speed adjustments, once you know the pitch angle from the Beckwith gauge, you go to the corresponding pitch angle graph and adjust the crest. Then, for Cruise Speed adjustments, after getting pitch angle, you use the formula to calculate the advance ratio, and obtain the point on the corresponding pitch angle graph to adjust that one.

Now I´ll see how it works out with the cruise speeds.

Cheers,
Aleatorylamp
 
Last edited:
Eeeeek!

Hello Aleatorylamp,

Green Tea will work, but if I drink a lot of it, it should be decaf.

The big EEEEEEK is because of how you interpreted my instructions.

Hopefully the reasoning described below makes sense.
With the new Hurricane Mk.I Power Coefficient Table, you are close.
VERY close.
Performance is slightly under and with the really great mechanics we have, should be slightly Higher, not Lower than specifications (unless there is a reason why it should not be).

So, the first step is to Drop the Zero Lift Drag.
That should raise the speed by a couple MPH and if this were my project, I would leave it there.

Since you are trying to be more exact, the next step would be slow the aeroplane back down.
Reducing Thrust would do that,
so you want to slightly REDUCE efficiency where it matters in Table 511.
So going from 0.89 to 0.91 makes no sense.
It should go DOWN, not UP!
These are Double Precision floating point, so the adjustments can be VERY fine.

Where should the adjustments be made?
From what you posted earlier, the Sea Level speed was closer or less below the target than speed at altitude.
That means when you change the Coefficient of Drag, you would probably need to bring the SL speed down more than altitude speed.

Here you got lucky.
With this Engine / Propeller, your SL speed is at 226 MPH which is exactly Advance Ratio 1.00.
This would affect altitude speed also but less.
If you are trying to adjust altitude speed more, go for Advance Ratio 1.20 instead.

- Ivan.
 
Hello Ivan,
Thanks for your helpful comments. So I can improve it even more now!

Following your instructions, I had put the larger Propeller diameter back in. This needed a reduction in Zero Lift Drag, so I reduced it by one point, from 58 to 57. It was not completely enough to compensate for the larger propeller, and required a very slight increase in Prop efficiency.

Had I made a greater Drag reduction, I would have noticed that Prop Efficiency had to be corrected in the opposite direction!

S.L. Performance is now only 0.3 mph fast, and higher up it´s about 0.5 mph faster, all quite OK.
Cruise speed manifold pressure settings have also improved slightly compared to the ones from the pilot´s manual. The differences are a little smaller, so that has also improved.

But: It seems that it can be improved further, by reducing Zero Lift Drag a little more... perhaps by two or three points, so then of course, propeller efficiency will need to be reduced instead of increased, and the Manifold Pressure settings for Cruise speeds will fall into place!

Which is what I will do after another cup of tea!

As always, thank you very much... This is all very interesting.
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I get the misunderstanding now. I was figuring that you would keep reducing the Zero Lift Drag until you got a speed increase over the amount you needed.

The reason I choose this method is that from a realism standpoint, 0.89 is a pretty high Propeller Efficiency.
I would hope to see something in the 0.80 to 0.85 at Maximum Speed.
Now keep in mind that this is just from a bit of reading and a bit of experimenting with AIR files so if you want to do things differently, you own the project.

The problems I am trying to address with my own projects are that the Propeller Pitch Range is limited to around 23-53 Degrees.
The high speed range of cruise to maximum level speed are more or less correct, but the propeller is lugging at the low "maneuvering" speeds and not getting off the low pitch value and not generating the amount of thrust (efficiency) that I would want.
This is with the A6M3 Model 22 and A6M5 Model 52 Type Zero Carrier Fighters.
That is also why I never continued the path and released a A6M3 Model 32 version.
The flight model just didn't quite do what I wanted and I didn't have a means of correcting it.
It is also a problem with the A6M2 Model 21b, but is less noticeable because the propeller pitch range was different with the engines on the "Mark I" fighters.
The Zeros were known for having quite excellent low speed acceleration which meant that they could restore energy lost to maneuvering very quickly. Since I cannot do that, I compensate a bit by reducing the energy lost in maneuvering by having an Oswald Efficiency number that is a bit lower than it should be.

With the Ki-61-Id, the flight test mentioned that the propeller came off the low speed stop at a bit over 100 MPH just after take-off. Mine is about 20-30 MPH too high which bothers me, but makes no real difference from a performance standpoint other than making the acceleration a little too low at the end of the take-off run.
The reason I chose the Ki-61 to do the experiments on is that it is a simpler problem overall with much less in the way of cascading effects.
This is not to say that the flight model is correct; It just happen to be about where I want it to be.

Thus I need to be able to tune just a part of the Power Coefficient Table and as long as I am doing that, I might as well be able to generate the whole curve instead of just knowing specifically where to poke to get the effects I am looking for. Smoother curves are better.

- Ivan.
 
Hello Ivan,
From what you are describing about the models you are working on, some behaviour details seem to be more difficult to reproduce on the sim model than others. Then it is all the more gratifying when something specific does work! The details you are working on seem to be very specific and quite complicated. Good luck!

Usually I don´t find so many details available for the older models I work with, and something similar is happening with the Fw200. The maximum speeds are falling in place very well, but strangely enough, they were better with my slightly increased Prop Efficiency and less reduced Airframe Drag, than with the last tests after reducing Airframe Drag further, and also reducing Prop Efficiency a little.

Sea-Level speeds ended up a few mph on the high side, and at altitude there were only very marginal increases of 0.5 or 0.2 mph, but I think I have discovered why.

Strangely enough, the specific Manifold Pressure details for the three or four cruise speeds mentioned in the pilot´s manual just wouldn´t fit in correctly, but I deduced why - it´s a really stupid thing: They come from the documentation referring to one of the units of the Fw200-A0 limited production run, which were built while the first 3 initial prototypes were still being tested, and some of these fitted the 800 hp BMW 132-H or -L engines!

So obviously the 720 Hp engines on the prototype machine that flew the Berlin-New York record flight need different manifold pressure settings for said cruising speeds! That took a while to sink in... so I can discard that information. The lower Hp would also account for why it´s not working to increase altitude performance.

So it seems that the air file with the first modification of Table 511 after incorporating the Hurricane´s table 512 is more correct.
Anyway, it´s very pleasing how this is all turning out thanks to your indefatigable counselling!

I´m just preparing the new spec sheet for the performance of the new ungeared, 9.7 ft propeller engine, and I´ll post the new .air file. BTW, you are right about the 0.89 efficiency being too high for advance-ratio 1. It´s at 0.8585 - the 0.89 come from a higher pitch angle graph peak to the right! When I was adjusting the peaks at first, it wasn´t all that clear to me where I was. Sorry!

Cheers,
Aleatorylamp
 
Last edited:
Hello Ivan,
As requested and promised, attached below are the updated FD and Performance document for the Fw200A (V2) Condor I am working on, (2nd and 3rd prototypes). Incidentally, V1 was the presentation prototype and had 760 Hp Hornet engines and slightly different wings.
The propeller is now ungeared, 9.7 ft in diameter, Table 512 comes from the Hurricane, and Table 511 is slightly tweaked to correct S.L. max. speed. Cruise speeds coincide with general specs described for the Fw200A, i.e. 0.7 ATA for Eco-Cruise and 0.8 ATA for Cruise.
I forgot to mention: RPM is a bit low at 2025 all round, instead of 2050. This coincides with what happened of other models, e.g. Zeppelin Staaken RVI and AT-9 Fledgling, and could be something to do with my computer. I remember you were getting correct RPM readings on your machine.
Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I will take a look when I get a chance.
I will be out of town for a couple days.
Internet and Email access will be via cell phone, so although I can get messages periodically, I won't try to type anything significant.

- Ivan.
 
Hello Ivan,
Not to worry, I hope you have fun. I´m also taking my Easter Week off classes. A well earned holiday is good for anyone and everyone. No hurry with looking into the .air file, so that is at your leisure when you get back.

I´ve started on the Virtual Cockpit. It´s hopefully going to have a textured instrument dashboard and if possible, textured sides too, which I plan to add via SCASM. I should be able to do it because we did one for the AT-9 Fledgling and the Zeppelin Staaken R.VI.

Then, with a decent .air file, a reasonable custom panel and the new custom gauges, together with the Virtual Cockpit, it should be a worthy CFS1 upload. We´ll see if it can be done well enough.
Cheers,
Aleatorylamp
 
Hello Aleatorylamp, I actually had a chance to take a quick look at your FW 200 before I left. The exterior model looks pretty good The flight model seems to behave well enough in the air. It is way slow for acceleration on take-off as one might expect from so little engine power on such a large machine. (It barely reaches take-off speed on the short runway I have on the Pooh Island Test Airfield, but that seems right.) It is nicely ponderous as one would expect from such a large beast. One very noticeable issue is that the aeroplane is dropped into the simulator in a way that puts the tailwheel underground. That is why it has such a huge jump right after loading. From what I can tell it has only one main panel without any other sub panels. Are there any other engine controls such as throttle, magnetos or starter controls? Are there any fuel gauges? This is being posted from a Hotel Guest computer. - Ivan.
 
Hello Ivan,
Thanks for the reply from you hotel, and thanks for trying out the model before you left.

I thought I had already aligned the three wheels with their shadows on the ground on the new .air file with the engine corrections, but I´ve just checked, and when re-loading the plane into the sim, you´re right, the tail jumps! I´ll see to it, thanks!

With respect to the accelleration, I´ll try and find out what the take off run was in reality.
I wonder if it´s improvable without affecting behaviour during flight.
The specs quote the speed for raising the tail as 56 mph and take-off between 97 and 87 mph.

As regards the panel, it´s provisional and the only good thing about it is the new engine gauges, basically.
For the moment there are no sub-panels and as always, fitting other adequate 4-engined gauges is a problem, and that is still pending. For the moment fuel-related gauges are from the Fw190, the throttle ones from the Default Cessna FSFS Conv, and as the 4 ignition switches from the FS98 Condor are only replicas of the Default Cessna one I haven´t put them in.
So, I´m not really very sure about what to do.
Another thing is the pilot´s position or view point, which will have to be shifted sideways for the virtual cockpit, but then it won´t be coherent with the Cockpit Panel, so perhaps I will have to revert to the 2/3 Panel view.

Cheers,
Aleatorylamp
 
Thrust levers

Hello Ivan,
I remembered that I´d altered the bitmaps on the Lear45 dual-thrust levers for the Baltimore and the Dornier. The FSFS Conv gauges for the 4-engined light jet are very similar, so I put rounded ivory-coloured handles on those, and duplicated the base. The result looks similar to the 4 levers in the Condor cockpit, although there are quite a lot more levers in there. I´d say it looks a bit better than the Cessna182 Throttles. Here´s a screenshot of the gauge to see what you think!
Searching for info on the take-off run, all I found was a comment about it not being good on short runways, but I´m still looking.
Cheers,
Aleatorylamp
 

Attachments

  • thrust-4.jpg
    thrust-4.jpg
    4.8 KB · Views: 0
Hello Aleatorylamp,

We got back home this evening.
I wasn't commenting that the slow acceleration was wrong. I was just noting that it was slow as expected.
I found that one notch of flaps seemed about right to get off the short runway at Pooh Field.
Another thing worth looking for is the Propeller Pitch Range. If the low stop is too low, the acceleration tends to be higher than it should be.

I see from your earlier screenshot that there were actual throttles and a fuel gauge and they are not appearing on my version, so perhaps I need to see why that is the case.

During the trip, I came up with an idea for generating the Propeller Efficiency Tables but need to figure out whether or not I can do what I want within a spreadsheet. That would only be about 1/4 of the entire problem though.

- Ivan.
 
You must log in or register to reply here.
Back
Top